“A PROSPECTIVE RANDOMISED STUDY COMPARING LATERAL AND POSTERIOR APPROACH IN ULTRASOUND
GUIDED PARASAGITTAL IN-PLANE INFRACLAVICULAR BRACHIAL PLEXUS BLOCK”
A Dissertation submitted to
THE TAMILNADU DR. M.G.R. MEDICAL UNIVERSITY
In partial fulfilment of the requirements for the award of the degree
M.D. (BRANCH-X) ANAESTHESIOLOGY
GOVERNMENT STANLEY MEDICAL COLLEGE & HOSPITAL
THE TAMILNADU DR. M.G.R. MEDICAL UNIVERSITY CHENNAI, TAMILNADU
APRIL 2017
DECLARATION BY THE CANDIDATE
I, Dr.S.KATHIRVIZHI, solemnly declare that the dissertation, titled “A PROSPECTIVE RANDOMISED STUDY COMPARING LATERAL AND POSTERIOR APPROACH IN ULTRASOUND GUIDED PARASAGITTAL IN-PLANE INFRACLAVICULAR BRACHIAL PLEXUS BLOCK”, is a bonafide work done by me during the period of FEBRUARY 2016 TO JULY 2016 at Government Stanley Medical College and Hospital, Chennai under the expert supervision of Dr.V.NALINI, M.D., D.A., Professor, Department Of Anaesthesiology, Government Stanley Medical College, Chennai.
This thesis is submitted to The Tamil Nadu Dr. M.G.R. Medical University in partial fulfilment of the rules and regulations for the M.D.
degree examinations in Anaesthesiology to be held in April 2017.
Chennai-1 Dr. S. KATHIRVIZHI
Date:
CERTIFICATE BY THE GUIDE
This is to certify that the dissertation titled "A PROSPECTIVE RANDOMISED STUDY COMPARING LATERAL AND POSTERIOR APPROACH IN ULTRASOUND GUIDED PARASAGITTAL IN- PLANE INFRACLAVICULAR BRACHIAL PLEXUS BLOCK" is a genuine work done by Dr.S. KATHIRVIZHI for the partial fulfilment of the requirements for M.D. (Anaesthesiology) Examination of The Tamilnadu Dr. M.G.R. Medical University to be held in April 2017, under my supervision and guidance.
Dr.V. NALINI, M.D., D.A., Professor and Guide,
Department of Anaesthesiology,
Govt. Stanley Medical College and Hospital, Chennai - 600 001.
CERTIFICATE BY HEAD OF THE DEPARTMENT
This is to certify that the dissertation titled "A PROSPECTIVE RANDOMISED STUDY COMPARING LATERAL AND POSTERIOR APPROACH IN ULTRASOUND GUIDED PARASAGITTAL IN-PLANE INFRACLAVICULAR BRACHIAL PLEXUS BLOCK" is a genuine work done by Dr. S. KATHIRVIZHI for the partial fulfilment of the requirements for M.D.(Anaesthesiology) Examination of The Tamilnadu Dr. M.G.R. Medical University to be held in April 2017, under my supervision and guidance.
Dr. S. PONNAMBALA NAMASIVAYAM, M.D., D.A., D.N.B., Professor and HOD
Department of Anaesthesiology, Govt. Stanley Medical College, Chennai - 600 001.
ENDORSEMENT BY HEAD OF THE INSTITUTION
This is to certify that the dissertation "A PROSPECTIVE RANDOMISED STUDY COMPARING LATERAL AND POSTERIOR APPROACH IN ULTRASOUND GUIDED PARASAGITTAL IN-PLANE INFRACLAVICULAR BRACHIAL PLEXUS BLOCK" presented herein by Dr.S. KATHIRVIZHI is an original work done in the Department of Anaesthesiology, Government Stanley Medical College and Hospital, Chennai in partial fulfilment of regulations of the Tamilnadu Dr. M.G.R. Medical University for the award of degree of M.D. (Anaesthesiology) Branch X, under my supervision during the academic period 2014-2017.
Dr. ISSAC CHRISTIAN MOSES, M.D., FICP., FACP., Dean
Govt. Stanley Medical College, Chennai -600001.
ACKNOWLEDGEMENTS
I wish to express my sincere thanks to Prof. Dr. ISSAC CHRISTIAN MOSES, M.D., FICP., FACP., Dean, Government Stanley Medical College and Hospital for having permitted me to utilize the facilities of the hospital for the conduct of the study.
My heartfelt gratitude to Prof. Dr. V. NALINI, M.D., D.A., Professor, Department of Anaesthesiology, Government Stanley Medical College and Hospital for her motivation, valuable suggestions, expert supervision, guidance and for making all necessary arrangements for conducting this study.
I thank Prof. Dr. PONNAMBALA NAMASIVAYAM, M.D., D.A., DNB., Professor and Head, Department of Anaesthesiology, Government Stanley Medical College and Hospital for his constant encouragement and support.
I thank Prof. Dr. KUMUDHA LINGARAJ, M.D., D.A., for her constant motivation and support apart from providing valuable suggestions in carrying out this study.
I thank Prof. Dr S. DHANASEKARAN, M.D., D.A., for his invaluable encouragement throughout the course of the study.
I thank Prof. Dr. K. SEVAGAMOORTHY M.D., D.A., for his constant motivation and valuable suggestions in carrying out this study.
I thank Prof. Dr. NAHEED AZHAR, M.D., DA., for his constant support and encouragement.
I express my heartfelt gratitude to my Assistant Professors DR.MAHENDRAN, D.A., DR.S.MAHALAKSHMI, M.D., DR.S.SARAVANAKUMAR, M.D., DNB, DR.VIJAYANAND, M.D, D.A., DR.V.J.KARTHIK, M.D., and DR.NARASIMHAN, M.D., who had evinced constant and keen interest in the progress of my study right from the inception till the very end and were instrumental in the successful completion of the study.
I wish to thank all my Assistant Professors especially for their aid and encouragement during the study.
I thank Mr. VENKATESAN, for helping me in statistical analysis. My sincere thanks to all those post graduates who helped me during this study period.
I thank the staff nurses and theatre personnel, Government Stanley Medical College and Hospital for their cooperation and assistance. I owe my gratitude to all the patients included in the study and their relatives, for their whole hearted co-operation and consent.
CONTENTS
SL.
NO
TITLE PAGE
NO.
1. Introduction 2. Aim of the study
3. History of Brachial Plexus Block
4. Anatomy and Formation of Brachial plexus 5. Ultrasonography
6. Infraclavicular approach to Brachial Plexus Block 7. Pharmacology
8. Review of literature 9. Materials and Methods 10. Observation and results 11. Discussion
12. Conclusion 13. Bibliography 14. Annexures
a. Ethical committee approval letter b. Proforma
c. Informed consent form d. Master Chart
e. Plagiarism certificate
LIST OF TABLES
SL.
NO TABLE PAGE
NO.
1. Testing of sensory and motor block of Brachial Plexus Block
2. Distribution across the ranges of age 3. Age Distribution
4. Comparison of Weight
5. Comparison of Gender distribution 6. Duration of surgery
7. Surgical area distribution
8. Comparison of Block Performance time 9. Sensory Block in Radial Nerve distribution 10. Sensory Block in Median Nerve distribution 11. Sensory Block in Ulnar Nerve distribution 12. Sensory Block in Musculocutaneous Nerve
distribution
13. Motor Block in Radial Nerve distribution 14. Motor Block in Median Nerve distribution 15. Motor Block in Ulnar Nerve distribution
SL.
NO TABLE PAGE
NO.
16. Motor Block in Musculocutaneous Nerve distribution 17. Duration of onset of surgical anaesthesia
18. Onset of Surgical anaesthesia 19. Anaesthesia Related time 20. Duration of Motor block 21. Duration of Sensory block 22. Vessel puncture
23. Pneumothorax
24. Local Anaesthetic Toxicity
LIST OF FIGURES
SL.NO TITLE PAGE
NO.
1. The Schema of Brachial Plexus 2. Branches of the Brachial Plexus 3. Distribution of Brachial Plexus
4. Brachial plexus anatomy important to Infraclavicular block
5. Interaction of Ultrasound with Tissues 6. Types of Tranducers
7. In-plane and Out of plane approaches
8. Midclavicular approach of infraclavicular block 9. Ultrasound anatomy of infraclavicular block 10. Structural formula of Bupivacaine
11. Structural formula of Lignocaine 12. Derivation of sample size
13. Esoate Ultrasound Machine 14. High frequency linear probe
15. Probe position and needle insertion site (lateral approach)
SL.NO TITLE PAGE NO.
16. Needle tip at the posterior cord (lateral approach) 17. Parasagittal section showing block needle and
ultrasound probe
18. Probe position and needle insertion site (posterior approach)
19. Needle tip at the posterior cord (posterior approach) 20. Comparison of Age range
21. Comparison of Age distribution 22. Comparison of Weight
23. Gender distribution 24. Duration of surgery 25. Surgical area distribution
26. Comparison of Block Performance time 27. Sensory Block in Radial Nerve distribution 28. Sensory Block in Median Nerve distribution 29. Sensory Block in Ulnar Nerve distribution 30. Sensory Block in Musculocutaneous Nerve
distribution
SL.NO TITLE PAGE NO.
31. Motor Block in Radial Nerve distribution 32. Motor Block in Median Nerve distribution 33. Motor Block in Ulnar Nerve distribution
34.
Motor Block in Musculocutaneous Nerve distribution
35. Duration of onset of surgical anaesthesia 36. Onset of Surgical anaesthesia
37. Anaesthesia Related time 38. Duration of Motor block 39. Duration of Sensory block 40. Vessel puncture
41. Pneumothorax
42. Local anaesthetic toxicity
1
CHAPTER 1 INTRODUCTION
Peripheral nerve blockade is the cornerstone of regional anaesthesia and pain management. Brachial plexus blocks are an alternative to general anaesthesia for surgeries of the upper limb, avoiding the risks of airway manipulation, hemodynamic instability, cognitive dysfunction and postoperative nausea and vomiting1,2.
It is the reversible blockade of nerve conduction by local anaesthetics in the region where it is applied. Regional anaesthetic techniques have the advantages of reduced morbidity, mortality, superior postoperative analgesia, cost effectiveness and lower rate of serious complications3.
Nerves of the upper extremity can be approached at every anatomic division of the brachial plexus from the nerve roots to the terminal branches. Based on the level along the brachial plexus where the needle is placed, the various approaches are, interscalene, supraclavicular infraclavicular and the axillary approach4.
The integral part of peripheral nerve blockade is to localise the needle close to the nerve to ensure adequate neural blockade but not so
2
close as to injure the nerve. Initially peripheral nerve blockade was performed based on landmark technique by eliciting paraesthesia. This technique had high failure rates and injury to neurovascular structures leading to the invention of peripheral nerve stimulator.
Nerve stimulation proved to be a better technique than conventional paraesthesia approach, yet with adverse effects like neurovascular injuries leading to permanent nerve damage and pneumothorax5.
Real time ultrasound guided peripheral nerve blockade revolutionized the field of regional anaesthesia by enhanced visualisation of the neural target and the surrounding structures, spread of the local anaesthetic agent, identification of the anatomical anomalies6. Ultrasound improved the quality of blocks and is a safe and better alternative to the conventional methods.
Surgeries of the hand, forearm and the arm are indications for supraclavicular and infraclavicular blocks.
Infraclavicular block performed at the level of the cords provides complete anaesthesia of the axillary and the musculocutaneous nerves
3
than the other approaches. Various methods of this block are the paracoracoid and midclavicular approaches7.
The ultrasound guided lateral parasagittal approach, the conventional approach has a drawback of impaired needle visualisation since brachial plexus at the infraclavicular level is deeper with steep angle of needle trajectory to the ultrasound beam. So a newer ultrasound guided posterior parasagittal in-plane infraclavicular brachial plexus block was introduced with better needle visualisation8.
Hence a study was planned to compare the anaesthetic efficacy of ultrasound guided lateral parasagittal and posterior parasagittal approaches of infraclavicular block in forearm and hand surgeries.
4
CHAPTER 2 AIM OF THE STUDY
The aim of this randomised study was to compare the anaesthetic efficacy of ultrasound guided lateral parasagittal and posterior parasagittal approaches of infraclavicular brachial plexus block in forearm and hand surgeries.
PRIMARY OBJECTIVES
The primary objectives of this study were to assess
1. Sensory blockade of radial, median, ulnar and musculocutaneous nerves.
2. Motor blockade of radial, median, ulnar and musculocutaneous nerves.
3. Surgical anaesthesia.
SECONDARY OBJECTIVES
The secondary objectives were to assess 1. Total anaesthesia related time
2. Procedural complications – Vascular puncture, accidental paresthesia
3. Complications –pneumothorax, intravascular injection, features of local anaesthetic toxicity.
5
CHAPTER 3
HISTORY OF BRACHIAL PLEXUS BLOCK
In 1885, the first recorded brachial plexus block in history was performed by William Stewart Halsted, who surgically exposed the Brachial plexus and injected cocaine into its nerve roots under direct vision9.
In 1897, George Crile modified this technique in which Brachial plexus was exposed behind the sternocleidomastoid muscle with local anaesthesia and cocaine was injected into nerve trunks under direct vision10.
In 1911, Percutaneous approaches to Supraclavicular block was introduced by Diedrich Kulenkampff, who used the midpoint of the clavicle and the subclavian artery as the landmark, at the point where External jugular vein intersects the clavicle. The needle was directed backwards, inwards and downwards to the first rib. This technique was limited by the risk of pneumothorax11.
Labat, in 192212, described injecting local anesthetic at three separate points which failed to elicit paresthesia by Kulenkampff’s method. Modification of Kulenkampff’s technique was done by
6
Livingston in 1926 without eliciting paresthesia once the deep cervical fascia is penetrated.
In 1940, Patrick described an approach which was coated as the
“Classical supraclavicular technique”. Knight, in 1942 modified Patrick’s approach by three injections through three parallel needle insertions13.
Single injection technique was introduced by Murphy in 1944 who used lateral border of anterior scalene muscle as the landmark and inserted the needle caudally as in Knight’s technique.
Following various aspects of Kulenkampff’s and Patrick’s technique, in 1949 Bonica and Moore injected local anaesthetic solution by “Walking the rib” and made multiple injections during each withdrawal of the needle.
In 1958, Lookman suggested the significance of fascial sheath surrounding the Brachial plexus. Fortin and Tremblay advised using short needle to minimize pleural injury.
Brachial plexus was localised using electrical stimulation by Perthes in 1928.Pearson in 1955 located motor nerves by electrical stimulation using insulated needle. The report of Block -Aid monitor for nerve blocks by Weight in 1969 made the technique popular and feasible.
7
In 1917, Bazy and Paucet14 introduced the infraclavicular approach to Brachial plexus block which was modified by Raj15 and his associates directing the needle laterally and using a nerve stimulator. Infraclavicular block by coracoid approach was popularised by Wilson in 1998.
The modern era of brachial plexus block evolved when La Grange and his associates in 1978 described the use of Doppler ultrasound to locate Subclavian artery for supraclavicular block16,17. In 1981, Ahramowitz and Cohen used Doppler ultrasound and localised the axillary artery for axillary nerve block18.
In 1988 Vaghadia19 and Jenkins advocated the use of Doppler ultrasonogram for intercostal nerve block. Ultrasonogram became an integral part in peripheral nerve blockade after Ting in 1989, who used B mode ultrasonography for axillary nerve blocks and has become an indispensable tool in regional anesthesia.
8
CHAPTER 4
ANATOMY AND FORMATION OF BRACHIAL PLEXUS
20-23A thorough knowledge of the Brachial plexus anatomy is required in performing upper extremity regional anesthesia, to understand the technical aspects of block placement and to optimize patient specific blocks.
The Brachial plexus provides cutaneous and muscular innervation of the entire upper limb by its roots, trunks, divisions, cords and branches with few exceptions, the trapezius muscle innervated by the spinal accessory nerve and a patch of skin near the axilla innervated by the intercostobrachial nerve, cutaneous branch of the intercostal nerve. The brachial plexus as a network of nerves begin as spinal nerve roots and end as the terminal branches of the upper extremity.
9
FORMATION OF BRACHIAL PLEXUS
Figure 1. The schema of Brachial Plexus
ROOTS
The roots contribute the anterior primary divisions of lower four cervical and first thoracic nerve. The five roots arise from the intervertebral foramina, passes behind the foramen transversarium of the cervical vertebra, then reaches the space between the anterior and posterior tubercles of the transverse process of the respective vertebra.
10
TRUNKS
Near the medial border of the middle scalene muscle, the C5 and C6 rami join to form the superior trunk of the Brachial plexus.C7 continues to form middle trunk.C8 and T1 rami unite to form the inferior trunk. The trunks arise from between the scalene muscles and pass downward and laterally across the posterior triangle and the first rib.
DIVISIONS
Behind the clavicle, at the lateral border of the first rib, each trunk divides into anterior and posterior divisions. The six divisions course into the axilla and join to form cords of the Brachial plexus.
CORDS
Divisions undergo a level of reorganization into cords, defined by their relationship to the second part of the axillary artery. The anterior divisions of the upper and middle trunk form the lateral cord. Medial cord is the continuation of the anterior division of the lower trunk. Posterior divisions of the all three trunks contribute the posterior cord.
Lateral and medial cords give rise to the nerves which supply the flexor surface of the upper extremity. Nerve arising from the posterior cord supply the extensor surface of the upper extremity.
11
DISTRIBUTION OF THE BRACHIAL PLEXUS 24
Figure 2. Branches of the brachial plexus
12
Figure 3. Dermatomal, Myotomal & Sclerotomal Distribution of Brachial Plexus
13
The roots receive
· Grey rami from the cervical sympathetic chain
· C5 and C6 from middle cervical ganglion
· C7 and C8 from inferior cervical ganglion
· T1 from its ganglion The Roots supply:
· To longus cervicis (C5–C8);
· To the scalene muscles (C5–C8);
· Nerve to rhomboids (C5);
· Nerve to serratus anterior (C5–C7);
· Contribution to the phrenic nerve (C5).
The Trunks give:
· Nerve to subclavius (C5, 6);
· Suprascapular nerve (C5, 6).
14
The Cords give:
(a) Lateral Cord
· Lateral pectoral nerve (C5–C7);
· Musculocutaneous nerve (C5–C7);
· Lateral head of median nerve (C6, C7) (b) Medial Cord
· Medial pectoral nerve (C8, T1);
· Medial cutaneous nerve of arm (C8, T1);
· Medial cutaneous nerve of forearm (C8, T1);
· Medial head of median nerve (C8, T1);
· Ulnar nerve (C7–C8, T1);
(c) Posterior Cord
· Upper subscapular nerve (C5, C6);
· Nerve to latissimus dorsi (thoracodorsal nerve) (C6–C8);
· Lower subscapular nerve (C5, C6);
· Axillary nerve (C5, C6);
· Radial nerve (C5–C8, T1).
15
RELATIONS OF THE BRACHIAL PLEXUS25
Figure 4: Brachial plexus anatomy relevant to infraclavicular block
Roots of the plexus lie above the second part of the subclavian artery, sandwiched between the scalenus anterior and medius muscle. As the roots emerge along the transverse process of the cervical vertebra, they lie between two sheaths of brachial plexus. The trunks of the plexus are invested in prevertebral fascia covered by skin, platysma and deep fascia in the posterior triangle. Trunks are crossed by inferior belly of omohyoid, external jugular vein, transversal cervical artery, subclavius muscle, suprascapular vessels and supraclavicular nerves.
The divisions lie behind the clavicle, at the lateral border of the first rib and descends into the axilla.
At the apex of the axilla, the cords are formed around the axillary artery, medial cord lies behind the artery with posterior and lateral cords lateral to this vessel. But behind the pectoralis minor they take up their relations signified by their names.
16
CHAPTER 5
ULTRASONOGRAPHY
Ultrasound waves are the sound waves with frequency above the audible upper limit of human beings, greater than 20,000 Hz. Application of ultrasound waves to visualise the internal organs and structures of the human beings is referred as Medical ultrasound26.
Ultrasound imaging provides visualisation of peripheral nerves, needle tip and local anaesthetic distribution using frequencies in the range of 3 – 20 MHz
ULTRASOUND PRINCIPLE
The ultrasound transducer contains an array of piezoelectric crystals. When mechanical energy is applied to these crystals, electrical energy is generated by a phenomenon called “Piezoelectric effect”27. This was first described by The Curie Brothers, Pierre curie and Jacques Curie in 188028.
Reverse Piezoelectric effect is the phenomenon in which electrical energy applied to the Piezoelectric crystals generated vibrations in the
17
form of mechanical energy. This explains the principle how the ultrasound waves are generated.
ULTRASOUND WAVELENGTH AND FREQUENCY29
Wavelength and frequency of ultrasound are inversely related.
High frequency ultrasound waves (10 -20 MHz) provides images with high axial resolution but will not penetrate deeper. Hence high frequency waves are used optimally in imaging the superficial structures less than 3 cm from the surface like interscalene brachial plexus and superficial nerves.
Midrange transducers (5 -10 MHz) are used to image structures 3 to 6 cm below the skin surface. They are utilised in imaging infraclavicular brachial plexus, sciatic nerve etc.,
A low frequency transducer (2 – 8 MHz) penetrates deeper tissues but has low axial resolution. Therefore, it is used in imaging the large nerves lying deeper such as the cords of brachial plexus surrounding second part of the axillary artery and the proximal part of the sciatic nerve.
18
ULTRASOUND TISSUE INTERACTION30
Transducer is the most limiting component of the ultrasound as it determines the characteristics of the energy, that is transmitted to deeper tissues, reflected back as echoes, partly scattered and partly transformed to heat. Optimal selection of the specific transducer characteristics results in better image acquisition, impact safety and lead to eventual block success.
PHYSICAL PROPERTIES OF ULTRASOUND WAVES28,29
REFLECTION
Acoustic impedance is a property which determines the amount of echo returning after hitting an interface. The intensity of this reflected echo is proportional to the mismatch in the acoustic impedances between two mediums.
REFRACTION
Ultrasound waves tend to change direction after hitting an interface between two media with different velocities of sound transmission. This property is called refraction and it leads to artefacts as the returning echoes are incorrectly located.
19
Figure 5. Interaction of Ultrasound with Tissues
SCATTERING
When ultrasound waves target the tissues at right angles they are reflected back to the transducer. If they are not at right angles they get scattered in all directions in a non-uniform manner.
ABSORPTION
A portion of the ultrasound waves incident on the tissues are absorbed and converted to heat.
ATTENUATION
Once the ultrasound energy leaves the transducer and enters the tissues it gets progressively degraded through absorption, scattering and
20
refraction. This amount of emitted energy that does not return to the transducer is known as the attenuation of ultrasound energy. This causes distortion or misrepresentation of anatomical relationships in the ultrasound image.
DIFFRACTION
Ultrasound waves spread out as it moves further away from the source and this property is called diffraction.
ANISOTROPY
Difference in echogenicity of soft tissues such as nerves and tendons when the angle of transducer is altered is known as anisotropy.
ARRAY CONFIGURATION OF TRANSDUCERS 31
Array configuration is the arrangement of elements along the face of the transducer which may be a linear array or a curved array according to the scanning surface.
21
Figure 6: Types of Transducers.
Linear array transducers consist of a narrow series (<1mm) of piezoelectric elements, arranged along the middle of a flat faced transducer. It provides anatomical visualisation of the structures that is in the same width at the skin surface in contact.
Curved or convex array transducers contain a narrow line of piezoelectric elements arranged along the middle of the convex (curved) faced transducer creating a fan like beam that widens with increasing penetration depth. It has the potential advantage of visualising deep structures with obstructing superficial anatomy such as bone.
Footprint or diameter of the transducer is selected to have optimal scanning and needle placement within the anatomical confines of the patient.
22
IMAGE CONSTRUCTION32
Transducers act as both a transmitter and receiver, emitting a short burst of ultrasound. They remain quiescent until detecting the returning echoes. This is called “Pulsed ultrasound”. The speed of ultrasound in our body tissues is 1540 m/s. Time taken for an echo to return determines the distance between the tissue and the probe. Across the plane of an image the ultrasound image is swept to form two-dimensional image one line at a time. These lines are summated to produce a frame. The frames are repeated to form a real time image. Brightness of the image formed is proportional to the amplitude of the returning echo.
NEEDLE INSERTION TECHNIQUES33: Figure 7: In-plane and Out of plane approaches
Two techniques are commonly used, the In-plane and Out of plane approaches. In the In-Plane technique, the needle is placed along the plane of ultrasound beam, so that the needle shaft with its tip is observed in longitudinal view as the needle is advanced. Tilting or rotating the transducer helps in alignment. In Out of plane technique, needle is inserted perpendicular to that of the transducer and is viewed in a cross-
23
sectional plane as a bright dot. Visualisation of the tip of the needle is difficult and not reliable in this technique.
SCANNING MODES34
A MODE (Amplitude mode): A mode displays a single echo signal against time to measure depth. B MODE (Brightness mode): It is a two- dimensional image produced by an array of transducers and a series of reflected echoes.
M MODE (Motion mode): It is a specialised type of B mode imaging where one particular line is ensonified repeatedly to examine a moving structure plotting out how it moves with time.
ULTRASOUND CONTROLS35
GAIN is used in altering the brightness of the image by amplifying the received signal.
TIME GAIN COMPENSATION (TGC) differentially amplifies signals from different depths, allowing equal amplitudes from all depths to be displayed.
FOCUS adjusts the beam to be at its narrowest at the required depth to image the region of interest. It thereby improves lateral resolution.
DEPTH can be adjusted to have the structure that is being examined to be in the centre of the screen.
24
CHAPTER 6
INFRACLAVICULAR APPROACH TO BRACHIAL PLEXUS BLOCK
Problems arising with axillary blocks such as incomplete dissemination of anaesthesia (radial and musculocutaneous nerves), pain from esmarch upper arm tourniquet, positioning difficulties (fractures) has lead to the development of an alternative approach, the infraclavicular approach36.Infraclavicular block approaches the cords of the brachial plexus and has gained significance after the development of ultrasound. It avoids the adverse effects of supraclavicular block, especially pneumothorax. It is more suitable for catheter insertion as the chest wall musculature helps in stabilizing the catheter and prevents its dislodgement compared to other superficial blocks.
INDICATIONS36
Surgeries of the distal upper arm, forearm and the hand.
CONTRAINDICATIONS
· Chest deformities
· Dislocated fracture of the clavicle
· Infection at the site of injection
· Local anesthetic allergy
25
METHODS OF LOCALISATION OF PLEXUS
MIDCLAVICULAR APPROACHES37
Figure 8: Midclavicular approach of infraclavicular block
Midclavicular approaches of infraclavicular block are the vertical and the anterolateral approach. In vertical approach the needle is inserted below the midpoint of the lower border of the clavicle until twitches are elicited. The needle path threatens the apical pleura and hence contraindicates this approach in children.
In anterolateral approach, the landmarks used are the coracoid process of the scapula, lower border of the clavicle and the deltopectoral groove. The needle is inserted 1 cm below the midpoint of the clavicle entering the neurovascular sheath 1 to 1.5 cm medial to the coracoid process of the scapula until twitches are seen in the arm, forearm or hand.
26
PARACORACOID APPROACH37
In this technique needle is inserted 1 to 2 cm caudal and medial to coracoid at the caudal extremity of deltopectoral groove until twitches are elicited.
ULTRASOUND GUIDED APPROACH
ULTRASOUND ANATOMY
Figure 9: Ultrasound anatomy of infraclavicular block
Orienting structure - Axillary artery
Structures to be identified - Axillary artery, axillary vein, cords of brachial plexus
Other structures seen - Pectoralis major, Pectoralis minor, rib, lung.
27
CHAPTER 7 PHARMACOLOGY
BUPIVACAINE38-40
Figure 10. Structural Formula of Bupivacaine
1-Butyl-N-(2,6-dimethylphenyl) piperidine-2-carboxamide.
Bupivacaine, an amino amide local anesthetic agent was synthesized by Ekenstam in 1957 and was first clinically used by LJ Telivuo in 1963. Bupivacaine has a wide spectrum of uses ranging from local infiltration, peripheral nerve block, sympathetic nerve block, epidural, caudal blocks to the extended release liposomal injection, recently approved.
CHEMISTRY
Bupivacaine is a pipecoloxylidide local anesthetic, chiral in nature as its molecule has an asymmetric carbon atom. It contains a tertiary
28
amine attached to a substituted aromatic ring by an amide linkage.
Adding a butyl group to the piperidine nitrogen atom makes bupivacaine more lipid soluble and potent than other drugs. Bupivacaine exists in a racemic mixture with two enantiomeric forms – Dextrorotatory (-R) and Levorotatory(-S) forms. The levorotatory form produces less neurotoxicity and cardiotoxicity than the dextrorotatory form.
PHYSIOCHEMICAL PROFILE
Molecular weight(base) – 288 Daltons.
pKa – 8.1
Lipid solubility – 28
Plasma protein binding – 95 %
Toxic plasma concentration - > 3 µg / mL MECHANISM OF ACTION
Bupivacaine exerts its action by binding to the voltage gated sodium channels and blocking sodium influx into the nerve cells thus preventing depolarisation. It maintains the sodium channels in the inactivated closed state and blocks nerve conduction.
29
PHARMACODYNAMICS
Bupivacaine exerts a stabilizing action on all excitable membranes.
Over dosage results in restlessness, tremors and convulsions in central nervous system and causes a reduction in automaticity of the heart. It is four times more potent than lignocaine with a slower onset and a longer duration of action. The sensory blockade produced is much more than the motor blockade.
PHARMACOKINETICS
The rate of absorption depends on the dose, concentration, route of administration, vascularity of the site and presence of vasoconstrictor drug. It binds to alpha -1 acid glycoprotein.
PHARMACOKINETIC PROFILE
Volume of distribution at steady state (Vdss) - 72 L Clearance – 0.47 L/min
Elimination t ½ - 210min
30
METABOLISM
Bupivacaine undergoes metabolism by various pathways like N- dealkylation, amide hydrolysis and conjugation. The N-dealkylated metabolite, N-desbutyl bupivacaine can be measured in blood and urine after spinal and epidural infiltration. Bupivacaine is degraded in the liver and less than 10 % of the drug is excreted unchanged in urine.
DOSAGE AND PREPARATIONS
Maximum dose - 2 to 3 mg/kg
Preparations - 0.25%, 0.5% solutions in 10 ml and 20 ml vials. Preservative free 0.5% and 0.75% for intrathecal injections.
CLINICAL APPLICATIONS
Peripheral nerve block - 0.25 – 0.5%
Epidural anaesthesia - 0.25 – 0.5%
Spinal anaesthesia - 0.5%, 0.75%
Caudal anaesthesia - 0.25 – 0.5%
Infiltration anaesthesia - 0.25 – 0.5%
31
CONTRAINDICATIONS
· Paracervical block.
· Known hypersensitivity to local anaesthetics
· Intravenous regional anaesthesia (IVRA) ADVERSE EFFECTS
Local anaesthetic systemic toxicity41(LAST) - Over dosage, accidental intravascular injection, slow metabolic degradation resulting in excess plasma concentration (>5µg/mL) causes neurotoxicity and cardiotoxicity.
CENTRAL NERVOUS SYSTEM TOXICITY
Depression of the inhibitory cortical neurons and inhibition of release of neurotransmitters results in excitation causing restlessness, dizziness, anxiety, tinnitus, blurred vision or tremors followed by seizures, unconsciousness and cardiac arrest. It is treated by maintaining oxygenation and ventilation, and by anticonvulsants.
CARDIOVASCULAR SYSTEM TOXICITY
Blockade of the cardiac sodium channels causes depression of conduction and automaticity of the heart manifesting as cardiac
32
dysrhythmias, atrioventricular block, ventricular tachycardia, ventricular fibrillation, bradycardia and asystole.
TREATMENT
Treatment aims at maintaining oxygenation and ventilation, circulatory support and removing local anesthetics from the receptor sites. Lipid emulsion 20%, 1.5mg/kg bolus over 1 min followed by an infusion of 0.25 ml/kg/min is administered.
LIGNOCAINE HYDROCHLORIDE42,43 Figure 11. Structural formula of lignocaine
In 1943, Nils Lofgren from Sweden synthesized a tertiary amide local anesthetic agent, diethyl aminoacetyl, 2,6, Xylidine hydrochloride monohydrate called lignocaine. It is a class 1b antiarrhythmic agent.
PHYSIOCHEMICAL PROFILE Molecular weight – 271 Daltons pKa - 7.8
Lipid solubility – 2.9
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Plasma protein binding – 70%
Toxic plasma concentration > 5µ/mL PHARMACODYNAMICS
Lignocaine inhibits the ionic fluxes causing conduction of impulses and hence stabilises neuronal membranes. Adrenaline prolongs its duration of action by producing vasoconstriction and reducing systemic absorption.
MECHANISM OF ACTION
Blockade of Voltage - gated sodium channels results in preventing the initiation of action potential. It reduces excitability of cardiac and neuronal tissue by conduction blockade. Sodium ion permeability is reduced thus slowing the rate of depolarisation.
PHARMACOKINETICS
Lignocaine has rapid onset of action and has duration of action of 60 – 120 minutes. 70 % of the drug binds to alpha-1 acid glycoprotein. It has an oral bioavailability of 35 % and topical bioavailability of 3 %.
PHARMACOKINETIC PROFILE
Volume of distribution at steady state (Vdss) – 91 L, Clearance – 0.95 L/min, Elimination t1/2 – 96 min
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METABOLISM
Lignocaine is metabolised by oxidative dealkylation in the liver to monoethyl glycine xylidide followed by its hydrolysis to xylidide. 75 % of the metabolite xylidide is excreted in the urine as 4 – hydroxyl -2,6- dimethyl aniline.
DOSAGE AND PREPARATIONS:
Safe dose of lignocaine is 3 mg/kg. When combined with adrenaline it is safe at 7 mg/kg. Adrenaline upto a concentration of 5 µg/ml (1: 200,000 dilutions) produces no systemic effects.
Lignocaine is used therapeutically in the following formulations:
Local infiltration and peripheral nerve block : 0.5 – 1 % Topical anaesthesia: 2 – 4 %
Eutectic mixture containing 2.5 % Lignocaine with 2.5 % prilocaine:
(EMLA cream)
Lignocaine jelly: 2 % for lubrication
Lignocaine viscous solution: 2 % Topical anesthesia of mucous membranes
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Topical patch: 5 % Lignocaine
Topical ointment: 5 % lignocaine for anorectal disorders
Lignocaine spray: 10 % for surface anesthesia in dental, ENT practice Lignocaine without preservative: 2 % 1-1.5 mg/kg i.v for ventricular arrhythmias and prevention of intubation response
Lignocaine for spinal anesthesia: 5 %
Biers block : Preservative free lignocaine 0.5 % without epinephrine.
TOXICITY:
Preservatives like methyl paraben stimulates production of antibody which leads to an allergic reaction. The preservatives are similar in structure to Para amino benzoic acid.
ADRENALINE/EPINEPHRINE44
Adrenaline is a sympathomimetic drug used along with local anesthetics in the concentration of 1: 200,000 (5µg/ml). By causing vasoconstriction, it delays absorption and maintains the concentration of the local anesthetic agent in the vicinity of the nerve fibres, thus prolonging their duration of action.
36
The duration of sensory blockade in lower extremities is prolonged when epinephrine (0.2 mg) is added to lignocaine or bupivacaine injected into subarachnoid space.
MECHANISM OF ACTION:
Agonist at alpha 1, beta 1, and beta 2 adrenergic receptors and mediates their action. It has poor lipid solubility and lacks cerebral effects.
USES:
1. Regulates the contractility of myocardium, vascular tone, smooth muscle tone and heart rate.
2. Potentiation of glandular secretion.
3. Treatment of life threatening allergic reactions like anaphylaxis 4. Used in Cardiopulmonary resuscitation.
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CHAPTER 8
REVIEW OF LITERATURE
Chiyo Ootaki, M.D45., et al studied the ultrasound guided infraclavicular block. Infraclavicular block have ununiformity of landmark and patient discomfort due to the use of longer needle and hence is less popular. So this study was done to note the advantages of ultrasonogram guidance and overcome the disadvantages that was previously present in this approach. 60 patients undergoing upper extremity surgery were selected. For all patients 7.0 MHz frequency probe is used. Probe was placed over the lateral head of the clavicle for all patients, visualising the subclavian artery and subclavian vein. 23 gauge needle is used for all the patients, 1.5 percent of lignocaine with 1:200000 concentration of adrenaline was the drug used. The drug was injected lateral and medial to the subclavian artery with a distance of 15 cm from the subclavian artery. Patients were evaluated for motor and sensory block after 30 minutes of the procedure. 95 % of patients (57 patients) proceeded with the surgery without supplementation intraoperatively. It was concluded that infraclavicular approach using real time ultrasonogram guidance produce more accurate block and less patient discomfort than landmark techniques.
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Y. Gurkan, S. Acar46 et al
Study was done on 80 patients posted for hand, wrist and forearm surgeries who were allocated into ultrasound guided or nerve stimulation groups. 20 ml of levobupivacaine, 5mg/ml and 20 ml of lidocaine and 20mg/ml with 5µg/ml epinephrine (40 ml in total) were used in both the groups. Efficacy of the block was better in the ultrasound group than nerve stimulation group in the distribution of radial nerve. Vascular puncture was observed in 3 patients of nerve stimulation group and none in ultrasound group. Hence it was concluded that the success rate of the block was comparable in both the groups with an improved quality in the ultrasound group.
N.S. Sandhu and L. M. Capan47 (2002) et al
They studied the ultrasound guided infraclavicular block.
Important aspects of this study included,
1. Imaging the axillary artery and the three cords of the brachial plexus posterior to pectoralis minor muscle.
2. Visualization of the Tuohy needle in its entirety.
3. Giving local anesthetics around the three cords.
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120 patients were selected and for all patients 2.5 MHz probe was used to visualize the three cords. 8-12 ml of 2% lignocaine with adrenaline 1:200000 concentration and sodium bicarbonate (0.9mEq /10 ml) was used. The drug was injected around each cord for all patients.
Complete surgical anaesthesia occurred in 90.4% of patients. Local anaesthetic supplementation was given for 7.2 percentage of patients.
2.4% of patients were converted to general anaesthesia for surgery. It was concluded that success rate and onset time was better with the ultrasonogram guidance in the infraclavicular block.
Vikas Trehan, Uma Srivastava48 et al (2010)
Study was conducted on 60 adult patients requiring surgery below mid humerus. They were randomly assigned to receive nerve stimulator guided infraclavicular block either by lateral coracoid approach (group L) or medial clavicular approach (group M). With 25 – 30 ml of 0.5 % bupivacaine, success rate was 87 % in group L and 73 % in group M. 14 patients had discomfort while performing the block in group M compared to 8 patients in group L. Both the approaches had a similar success rate.
But coracoid approach seemed better as block performance was less painful and coracoid process was an easier landmark.
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Dingemans, Emmanuel49 et al (2007)
A prospective randomised study was conducted on 72 patients.
Comparison was between ultrasound guided infraclavicular block (Group U) and ultrasound guided infraclavicular block with nerve stimulation (group S). In group U local anesthetic was deposited posterior to and on either side of the axillary artery. In group S, a single shot injection was given after obtaining a distal motor response with nerve stimulator.
Procedure times were shorter in group U. 86 % patients had complete sensory block in group U after 30 minutes compared to 57 % in group S.
Block supplementation was needed in 26 % in group S compared to 8 % in group U. This study concluded that ultrasound guided infraclavicular block is more rapidly performed and yields a higher success rate.
Beijing Ji Shui50 et al (2014)
40 patients undergoing elbow surgery received ultrasound guided continuous infraclavicular nerve block. Patients were randomly allocated to receive medial or lateral approach of infraclavicular block. All surgeries were conducted under general anesthesia. Postoperatively a portable pump was used for pain relief. This pump had a 250 ml reservoir that infused 0.2 % ropivacaine (5 ml/hr basal infusion rate, 5 ml bolus dose with 20 minutes lock out time). A study concluded that lateral
41
approach had a clear and stable anatomical structure, shorter procedure time and lesser number of side effects.
Frederiksen, Nielsen51 et al (2009)
A randomized study was conducted on 120 patients. Patients received either supraclavicular (group S) or infraclavicular (group I) nerve block. The mean block performance time was 5.7 minutes in group S and 5 minutes in group I. Block effectiveness was superior in group I (93 %) compared to group S (78 %). 32 patients in group S and 9 patients in group I had transient adverse events. The study concluded that infraclavicular block had a faster onset, better surgical effectiveness and fewer adverse events. Block performance time was comparable between the two groups.
Bigeleisen, Wilson52 et al (2006)
Using ultrasound two approaches of infraclavicular block, medial approach and lateral approach was compared in 202 patients. Ultrasound with an 8 MHz transducer was placed at the apex of deltopectoral groove.
The axillary artery and vein were imaged and the three cords identified.
The following parameters were observed in the study, block performance time, incidence of vascular puncture, quality of sensory and motor block.
42
The medial approach was quicker to perform and had a faster onset of blockade. Tourniquet pain was less with the medial approach and the plexus was closer to the skin (3.7 cm) compared to the lateral approach (4.5 cm). The lateral approach resulted in more number of vascular punctures. Both approaches provided good surgical anesthesia. Medial approach was easier to perform with an early block onset with less incidence of vascular puncture. The incidence of tourniquet pain was less in this approach and the brachial plexus was closer to the skin in this approach.
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CHAPTER 9
MATERIALS AND METHODS
This was a prospective randomized study done on patients undergoing surgeries of forearm, wrist and hand in the Institute for Research and Rehabilitation of Hand and the Department of Plastic Surgery, Stanley Medical College, Chennai.
After obtaining the approval of the Institutional Ethical Committee, a randomized, prospective study was conducted on 110 patients over a period of six months.
SAMPLE SIZE AND RANDOMIZATION:
Based on the previous study8 with a statistical power of 95 % and an alpha error of 0.05, the sample size for this case control study with equal number of cases was calculated using the following formula,
n = [(2pq) (Zα + Zβ)2] / [p1 – p0]2
where, n = sample size, p1 = [ p0R] / [1+ p0(R-1)] p = (1/2) (p1+p0) q = 1 – p q1 = 1 – p1 q0 = 1 - p0
Zα is the value from the standard normal distribution corresponding to α Zβ is the value from the standard normal distribution corresponding to β.
44
Figure 12: Derivation of sample size
Hence the sample size required for this study was calculated to be 110 with 55 patients in each group.
Randomization was done by allocating the patients to either the lateral group (Group L) or posterior group (Group P) by computer generated random numbers. Each group had 55 patients. The patients who met the inclusion and exclusion criteria were only included in the study.
PRE-ANESTHETIC EVALUATION:
Pre anesthetic assessment was done by recording a detailed history and performing a complete physical examination. Complete blood count, Renal function tests, blood grouping/typing, Random blood sugar,
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electrocardiograph and chest X ray were done. Patients were explained about the procedure in detail and written informed consent was obtained for the same.
SELECTION OF CASES:
INCLUSION CRITERIA:
All consented adult patients with 1. Age: 18 – 60 years
2. Both genders
3. ASA I and II physical status 4. BMI: 25 – 35 kg/m2
5. Undergoing forearm, wrist and hand surgeries.
EXCLUSION CRITERIA:
1. Patient refusal
2. Allergy to amide type local anesthetics 3. Infection at injection site
4. Coagulopathy
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5. Severe Obesity (BMI > 35 kg/m2) 6. Pregnancy
7. Pre-existing neuropathy MATERIALS:
The following equipment, drugs and monitors were kept ready for the conduct of anesthesia.
EQUIPMENT:
1. 18Gauge - 45mm cannula 2. 10 ml syringe
3. 10 cm extension tube
4. Sterile towels and gauze packs 5. Sterile gloves
6. Surgical spirit solution 7. Sponge holding forceps
8. Esoate My Lab 25 Gold Ultrasonogram Machine model 7340 with high frequency (10 – 18 MHz) linear array probe
9. Ultrasound probe Jelly
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Figure 13: Esoate Ultrasound Machine
Figure 14. High Frequency Linear Probe
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DRUGS:
1. 0.5 % Bupivacaine 2. 2% Lignocaine
3. Sterile Distilled Water MONITORS:
A multi parameter monitor was made available with 1. Electrocardiography
2. Non-invasive Blood Pressure 3. Pulse Oximetry
The following emergency drugs and equipment was kept ready.
1. Atropine 2. Adrenaline 3. Ephedrine 4. Midazolam 5. Propofol
6. Succinyl Choline
7. Intralipid Emulsion 20%
8. Laryngoscope with various sizes of blades.
9. Endotracheal Tubes
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10. Oropharyngeal airways 11. Oxygen source
12. Suction Apparatus 13. Ambu bag
METHODOLOGY:
110 patients between the ages of 18 to 60 years undergoing surgeries of the forearm and hand were randomized into two groups of 55 each. Patients received either Lateral or Posterior approach of ultrasound guided parasagittal in-plane infraclavicular brachial plexus block.
After shifting the patients to the operating theatre, they were randomized and allocated to either Group L receiving Lateral approach or Group P receiving the posterior approach.
An 18G i.v cannula was secured on the non-surgical limb and monitors were connected (pulse oximetry, electrocardiography, and non- invasive blood pressure monitoring). Intravenous fluid in the form of 0.9
% sodium chloride for diabetic patients and ringer lactate for non-diabetic patients were started at the rate of 100 mL/hr.
A local anesthetic mixture was prepared with equal volumes of 0.5 % Bupivacaine, 2 % Lignocaine and sterile distilled water.
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The Ultrasound machine (Esoate My Lab 25 Gold portable 2012, model no7340) was powered on and the linear array probe was covered with sterile dressing after applying sterile ultrasound gel. The ultrasound setting used to visualise was at a frequency of 18 MHz and a depth of 5 cm. The gain and focus were adjusted according to the image scanned.
The targets for both groups were the axillary artery, axillary vein and the cords of the brachial plexus.
GROUP L (LATERAL APPROACH)
In Group L, patient was placed in supine position with head turned to opposite side. The operating arm is positioned with 90̊ abduction at the shoulder joint and flexion at the elbow joint. A pillow was positioned underneath the shoulder blades so as to extend both shoulders, exposing the deltopectoral groove.
Figure 15. Probe position and needle insertion site (lateral approach)
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The probe was placed below the clavicle in the deltopectoral groove, medial to the coracoid process thus obtaining a parasagittal view and visualising the axillary artery, axillary vein and the cords of the brachial plexus.
Figure 16 : Needle tip at the posterior cord (lateral aaproach)
Needle was inserted at the cephalad (lateral) aspect of the ultrasound probe, below the clavicle and medial to the coracoid. The needle was strictly aligned along the long axis of the ultrasound approach (In Plane approach). After infiltrating the skin and subcutaneous tissue with 2 % lignocaine,18G 8 cm needle was introduced in plane with the probe.30 ml of the local anesthetic mixture was injected posterior to the artery.
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GROUP P (POSTERIOR APPROACH)
Figure 17: Parasagittal section showing block needle and ultrasound probe
Figure 18: Probe position and needle insertion site (posterior approach)
In Group P, patient was positioned in supine position with head turned to the opposite side. The operating arm was positioned in the neutral position by the side. A pillow was placed under the shoulder blades exposing the deltopectoral groove.
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The probe was placed below the clavicle and medial to the coracoid process in the deltopectoral groove (parasagittal view). The skin and subcutaneous tissue was infiltrated with 2 % lignocaine at the needle entry point.
Figure 19: Needle tip at the posterior cord (posterior aaproach)
The needle insertion point was over the trapezius muscle, sufficiently posterior allowing the needle to pass between the clavicle and the scapula along the direction of the axillary artery by in plane technique. This needle entry point was found to be 2 cm posterior to the clavicle avoiding needle tip contact with the inferior surface of the clavicle.
The needle was advanced till its tip reaches the posterior aspect of the axillary artery (6’o clock position). At this point 30 mL of local anesthetic mixture was injected achieving a ‘U’ shaped distribution of
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local anesthetic displacing the artery anteriorly. This is called the
“Double bubble sign53”.
ASSESSMENT OF BLOCK:
Sensory and motor functions were assessed in the innervations of the respective nerves. Sensory and motor functions in the contralateral limb were compared and used as a point of reference. Adequacy of the block is determined by assessing the motor and sensory blockade at predetermined intervals every 5 minutes from 10 minutes until 30 minutes. Time at which the block needle exited the skin was termed as time zero. Surgical anesthesia was defined as the ability to proceed with the surgery without the need for TIVA, general anaesthesia or rescue blocks.
SITES OF ASSESSMENT:
Table 1: Testing of sensory and motor block of Brachial Plexus Block
Nerve Motor Sensory
Median Flexion of index and middle fingers and thumb opposition
Volar aspect of the thumb
Radial Extension of wrist, thumb and index finger.
Lateral aspect of dorsum of hand
Ulnar Abduction of fingers and thumb Volar aspect of the fifth finger
Musculoc utaneous
Elbow flexion or forearm supination
Lateral aspect of the forearm
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Sensory assessment was documented based on a pin prick test comparing the pin prick sensation of the contralateral limb.
· pain-score 0 (No block)
· Analgesia -score1(feels touch but no pain)
· Anaesthesia-score 2(no pain, no touch sensation)
Motor function was assessed and graded according to the following scale,
· Score 0 - no weakness (normal contraction)
· Score 1- paresis (reduced contraction)
· Score 2 – paralysis (no contraction)
COMPOSITE SCORE:
Overall maximal composite score was 16 points. The patient is said to be ready when a minimal composite score of 14 points is achieved including a sensory block score equal to or more than 7 of 8 points. Time taken to obtain 14 points was defined as the onset time.
BLOCK PERFORMANCE TIME:
Imaging time was defined as the time interval between contact of the ultrasound probe with the patient and the acquisition of satisfactory
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sonoanatomy, which is the complete short axis view of the axillary artery.
Needling time is the time interval between the beginning of needle insertion and the end of local anesthetic injection through it. Performance time is the sum of the imaging time and the needling time. Block performance time was recorded by the anesthesia assistant with an electronic stop watch. Total anesthesia time is the sum of block performance time and the onset time.
The time for first request for analgesia was taken as the duration of the sensory blockade and the time for the resumption of full motor power was the duration of motor blockade.
FAILURE RATES
After assessing the sensory and motor block for 30 min if the composite score was less than 14 points, supplemental rescue analgesic measures were followed. It includes forearm peripheral nerve blockade, local anaesthetic infiltration by the surgeon or conversion to general anaesthesia.
These patients were labelled as block failure. Cases in which general anaesthesia is administered due to pain intraoperatively were also included in block failure.
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For anxious patients, additional dose of injection midazolam 0.25 mg/kg was given. All patients were supplemented with nasal oxygen 3 – 4 L/min through face mask intraoperatively. Patients were monitored throughout the procedure for complications like dyspnoea, symptoms of local anaesthetic toxicity and incidence of tourniquet pain. At the end of the procedure patients were transferred to the post anaesthesia care unit and monitored for 24 hours. They were supplemented with oral analgesic medications after six hours after the procedure and continued for two days.
ADVERSE EFFECTS
Accidental vessel puncture was identified by the appearance of blood in the syringe. Pneumothorax was diagnosed clinically by persistent cough, chest pain and dyspnoea within 24 hours after performance of the block and confirmed by chest x ray in suspected patients. Features of local anaesthetic toxicity was suspected in patients with symptoms like dizziness, restlessness, anxiety, numbness, blurred vision or tremors.
All the blocks in both the groups were performed by the principle investigator. Outcome measures were assessed by the anaesthesia resident except the block performance time which was recorded by the anaesthesia assistant.
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CHAPTER 10
OBSERVATION AND RESULTS
STATISTICAL TOOLS
The information gathered from the selected cases were noted in the master chart. The collected data were analysed with IBM.SPSS Statistics software 23.0 Version. To describe about the data, descriptive statistics, frequency analysis, percentage analysis were used for the categorical variables and the mean and standard deviation were used for continuous variables. To find the significant difference between the bivariate samples in Independent groups the Unpaired sample t-test was used. To find the significance in categorical data Chi-Square test and Fisher's exact test was used. In all the above statistical tools the probability value of <0.05 is considered as significant.
This study was designed to compare the lateral and posterior approaches in ultrasound guided parasagittal in plane infraclavicular Brachial plexus block for forearm and hand surgeries. 110 patients were selected and randomized.
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DEMOGRAPHIC PROFILE
AGE DISTRIBUTION
Figure 20: Comparison of Age range
Age distribution in the lateral group varied from a minimum of 18 years to a maximum of 60 years. The range of count upto 20 years is 12 patients, that is 21.8 %. In the age range from 21 to 30 years, the count is 27, that is 49.1%. from the age range between 31 to 40 years, the count is 7, that is 12.7 %. In 41 to 50 years group the count is 8, that is 14.5 %.
And in above 50 years group the count is 1, that is 1.8 %.
0%
20%
40%
60%
80%
100%
Lateral Posterior
Age Range
Upto 20 yrs 21 - 30 yrs 31 - 40 yrs 41 - 50 yrs Above 50 yrs
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Table 2: Distribution across the ranges of age
TABLE 2 AGE RANGE
GROUP L GROUP P T0TAL
Number of
patients % Number of
patients %
Number of patients
% Upto
20 yrs
12 21.8 4 7.3 16 14.5
21 to 30 yrs
27 49.1 27 49.1 54 49.1
31 to 40 yrs
7 12.7 14 25.5 21 19.1
41 to 50 yrs
8 14.5 9 16.5 17 15.5
Above 50 yrs
1 1.8 1 1.8 2 1.8
Total 55 100 55 100 110 100
‘p’ value 0.172
Age distribution in the lateral group varied from a minimum of 18 years to a maximum of 60 years. The range of count upto 20 years is 12 patients, that is 21.8 %. In the age range from 21 to 30 years, the count is 27, that is 49.1%. from the age range between 31 to 40 years, the count is
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7, that is 12.7 %. In 41 to 50 years group the count is 8, that is 14.5 %.
And in above 50 years group the count is 1, that is 1.8 %.
Age distribution in the posterior group varies from a minimum of 18 years to a maximum of 60 years in which upto 20 years, the count is 4, that is 7.3 %. In the age range from 21 to 30 years, the count is 27, that is 49.1%. In the group from 31 to 40 years, the count is 14, that is 25.5 %.
In 41 to 50 years group the count is 9, that is 16.4 %. And in above 50 years group the count is 1, that is 1.8 %. The distribution of patients across the age group was not significant with the p value of 0.172
Table 3: Age distribution
TABLE 3
AGE DISTRIBUTION
GROUP-L GROUP-P
MEAN(age in yrs) 28.49 30.76
S.D 9.463 9.391
‘p’ –value 0.209
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28
31
27 27 28 28 29 29 30 30 31 31 32
Lateral Posterior
Age distribution
Figure 21: Comparison of Age distribution
The mean age of patients in lateral group was 28.49 with S.D of 9.463. In posterior group the mean age of patients was 30.76 with S.D of 9.391. The age group p value is 0.209 which is statistically not significant.
WEIGHT DISTRIBUTION
The mean weight of the patients in lateral group was 57.07 with the SD of 4.055 and the mean weight in posterior group was 57.55 with the SD of 4.315. On analysing the data p value was found to be 0.555 which is not statistically significant.
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Figure 22: Comparison of weight
Table 4: Weight distribution TABLE 4
WEIGHT DISTRIBUTION
Weight(in Kgs) Group L Group P
Mean 57.07 57.55
SD 4.055 4.315
‘p’ value 0.555
57.07
57.55
56.80 56.90 57.00 57.10 57.20 57.30 57.40 57.50 57.60
Lateral Posterior
