Part 1 book “Understanding anesthetic equipment & procedures - A practical approach” has contents: Evolution of anesthesia practice, anesthesia equipment in india—a historical perspective, utility of physical principles in anesthetic practice, medical gas supply, storage, and safety, the anesthesia machine, pressure-reducing valves,… and other contents.
Understanding Anesthetic Equipment & Procedures A Practical Approach Understanding Anesthetic Equipment & Procedures A Practical Approach Editors Dwarkadas K Baheti MD Consultant Anesthesiologist and Pain Physician Bombay, Lilavati, Shushrusha, and Raheja Hospitals Mumbai, Maharashtra, India Former Professor and Head Department of Anesthesia and Pain Management Bombay Hospital Institute of Medical Sciences Mumbai, Maharashtra, India Vandana V Laheri DA MD Former Professor and Head Department of Anesthesia ESI PGIMSR and Mahatma Gandhi Memorial Hospital Mumbai, Maharashtra, India Former Professor Department of Anesthesia Lokmanya Tilak Municipal Medical College and General Hospital Mumbai, Maharashtra, India Foreword Dipankar Dasgupta The Health Sciences Publishers New Delhi | London | Philadelphia | Panama Jaypee Brothers Medical Publishers (P) Ltd Headquarters Jaypee Brothers Medical Publishers (P) Ltd 4838/24, Ansari Road, Daryaganj New Delhi 110 002, India Phone: +91-11-43574357 Fax: +91-11-43574314 Email: jaypee@jaypeebrothers.com Overseas Offices J.P Medical Ltd 83 Victoria Street, London SW1H 0HW (UK) Phone: +44-2031708910 Fax: +02-03-0086180 Email: info@jpmedpub.com Jaypee-Highlights Medical Publishers Inc City of Knowledge, Bld 237, Clayton Panama City, Panama Phone: +1 507-301-0496 Fax: +1 507-301-0499 Email: cservice@jphmedical.com Jaypee Medical Inc The Bourse 111 South Independence Mall East Suite 835, Philadelphia, PA 19106, USA Phone: +1 267-519-9789 Email: jpmed.us@gmail.com Jaypee Brothers Medical Publishers (P) Ltd 17/1-B Babar Road, Block-B, Shaymali Mohammadpur, Dhaka-1207 Bangladesh Mobile: +08801912003485 Email: jaypeedhaka@gmail.com Jaypee Brothers Medical Publishers (P) Ltd Bhotahity, Kathmandu Nepal Phone: +977-9741283608 Email: kathmandu@jaypeebrothers.com Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2015, Jaypee Brothers Medical Publishers The views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and not necessarily represent those of editor(s) of the book All rights reserved No part of this publication and may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of the publishers All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners The publisher is not associated with any product or vendor mentioned in this book Medical knowledge and practice change constantly This book is designed to provide accurate, authoritative information about the subject matter in question However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contraindications It is the responsibility of the practitioner to take all appropriate safety precautions Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/or damage to persons or property arising from or related to use of material in this book This book is sold on the understanding that the publisher is not engaged in providing professional medical services If such advice or services are required, the services of a competent medical professional should be sought Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity Inquiries for bulk sales may be solicited at: jaypee@jaypeebrothers.com Understanding Anesthetic Equipment & Procedures: A Practical Approach First Edition: 2015 ISBN 978-93-5152-124-2 Printed at Dedicated to Technicians, Engineers, Scientist, and Doctors Who made Anesthesiology What it is today!!! Contents Contributors xi Foreword xv Preface xvii Section 1: Historical Perspective Evolution of Anesthesia Practice Vandana V Laheri, Preeti G More Anesthesia Equipment in India—A Historical Perspective 18 Vasumathi M Divekar Section 2: Role of Physical Principles Utility of Physical Principles in Anesthetic Practice 25 Aparna S Budhakar, Shashank A Budhakar Sectioin 3: Medical Gases and Distribution System Medical Gas Supply, Storage, and Safety 33 Vandana V Laheri, Amit K Sarkar Section 4: Anesthesia Machine and its Components The Anesthesia Machine 61 M Ravishankar Pressure-reducing Valves (Pressure Regulators) 73 Vandana V Laheri Flowmeters 78 Preeti G More Vaporizers 88 Anjali A Pingle, Mandar V Galande Anesthetic Breathing Systems 113 M Ravishankar 10 Anesthesia Ventilators Anila D Malde 124 Understanding Anesthetic Equipment & Procedures: A Practical Approach Section 5: Airway Equipment 11 Face Masks 137 Naina P Dalvi, Nazmeen I Sayed 12 Laryngoscopes 143 Naina P Dalvi, Nazmeen I Sayed 13 Tracheal Tubes 161 Naina P Dalvi 14 Double Lumen Tubes and Bronchial Blockers 181 Vijaya P Patil, Bhakti D Trivedi, Madhavi D Desai 15 Cricothyrotomy: Emergency Surgical Airway of Choice 191 Vijaya P Patil 16 Supraglottic Airway Devices 197 Sheila N Myatra, Jeson R Doctor 17 Non-rebreathing Valves 212 Prerana N Shah 18 Airways 216 Prerana N Shah 19 Ventilating Systems—Manual Resuscitators 223 Prerana N Shah 20 Accessories, Connectors, Bite Block, Magill’s Forceps, Stylet, and Laryngeal Sprays 226 Prerana N Shah 21 Oxygen Therapy Devices and Humidification Systems 233 Raghbirsingh P Gehdoo, Sohan L Solanki 22 Video Laryngoscopy 239 Manoj R Shahane 23 Fiberoptic Airway Management 242 Anil Parakh, Ameya Panchwagh Section 6: Monitoring Equipment 24 Electrocardiogram Monitoring and Defibrillators 263 Samhita Kulkarni, Amit M Vora 25 Pulse Oximeters 268 Anila D Malde 26 Noninvasive and Invasive Blood Pressure Monitoring 283 Nandini M Dave, Amit Padvi 27 Capnography 288 Dinesh K Jagannathan, Bhavani S Kodali 28 Respiratory Gas Monitoring and Minimum Alveolar Concentration viii Sheila N Myatra, Sohan L Solanki 295 Contents 29 Bispectral Index 304 Ajit CS Pillai 30 Temperature Regulation and Patient Warming Devices 311 Satish K Kulkarni 31 Neuromuscular Blocks and Their Monitoring with Peripheral Nerve Stimulator 315 Falguni R Shah, Preeti A Padwal 32 Pulmonary Function Tests 326 Charulata M Deshpande, Sarika Ingle 33 Peripheral Venous Cannulation 339 Anil Agarwal, Sujeet KS Gautam, Dwarkadas K Baheti 34 Central Venous and Arterial Cannulation 345 Lipika A Baliarsing, Anjana D Sahu 35 Pulmonary Artery Catheterization 363 Sarita Fernandes 36 Cardiac Output Monitors 369 Vasundhra R Atre, Naina P Dalvi 37 Entropy 380 Naina P Dalvi, Nazmeen I Sayed 38 Somatosensory-evoked Potentials 385 Rajashree U Gandhe, Chinmaya P Bhave, Neeta V Karmarkar, Amruta A Ajgaonkar 39 Point-of-care Monitoring Equipment 391 Indrani HK Chincholi Section 7: Equipment for Central Neuraxial and Regional Blocks 40 Spinal, Epidural, and Combined Spinal–Epidural Anesthesia 413 Manjari S Muzoomdar, Preeti G More 41 Peripheral Nerve Stimulators/Locators, Needles, and Catheters 437 Aparna A Nerurkar, Devangi A Parikh 42 Ultrasound-guided Blocks 457 Manoj R Shahane 43 Infusion and Syringe Pumps 462 Smita D Sharma Section 8: Miscellaneous 44 How to Interpret X-rays, CT Scan, and MRI in Clinical Anesthesia Practice 471 Abhijit A Raut, Prashant S Naphade 45 Equipment for Anesthesia in Remote Locations 487 Aparna A Nerurkar, Devangi A Parikh ix Section 5: Airway Equipment Fig 5 Safar’s airway Fig 7 Berman airway Ovassapian airway, further research is needed in this field to meet the requirements of endoscopists in situations when it is crucial that equipment reliably fulfills its function.4 The Berman airway offers easier visualization of the vocal cords than the Ovassapian airway, provided that the Berman airway is of an adequate size and positioned in the midline Upon impingement of the intubation tube, completing the tracheal intubation is more difficult with the Berman airway than the Ovassapian airway (Fig 7).5 Ovassapian Fiberoptic Intubating Airway Fig 6 Connell airway allergy It can be cleaned with soap and water However, repeated sterilization may cause softening Its design could have use in the management of a patient’s airway during sedation (Fig 6).2 Berman Intubation Pharyngeal Airway 218 18.indd 218 Sizes are available for infant, small child, child, medium adult, and large adult It has no enclosed air channel The sides are cut open and there is support through the center The sides allow passage of suction catheters and provide air channels The center may have openings in it to permit suction if the airway becomes lodged sideways It has a flange at the buccal end It is easier to clean and is less likely to become obstructed with foreign body or mucus However, the anterior jaw lift was more effective than the Berman device for assisting fibreoptic orotracheal intubation.3 Though the Williams Airway Intubator and the Berman Oropharyngeal Airway were superior to It is designed for use during fiberoptic intubation The proximal end is tubular and narrow that gradually widens at the distal end The distal part does not have any posterior wall Hence, the distal end of the fiberscope can be maneuvered in this open space in the oropharynx The lingual surface is flat There are two side walls and two pairs of curved guide walls between the side walls The guide walls curve toward each other, leaving a space for a tracheal tube up to size and are flexible so that the airway can be removed from around the tracheal tube after intubation has been completed It is not necessary to remove the tracheal tube connector when using this airway for fibreoptic intubation (Fig. 8) Patil-Syracuse Oral Airway or Patil Endoscopic Airway It is made of aluminum and is useful for fiberoptic intubation It has lateral suction channels, groove in the center of the lingual surface for fiberoptic scope and a slit in the distal end that allows manipulation in the anteroposterior direction (Fig 9) Williams Airway Intubator The Williams airway intubator was designed for blind orotracheal intubations It can also be used to aid fiberoptic intubations or 8/19/2014 12:50:55 PM Chapter 18: Airways Fig 8 Ovassapian fiberoptic intubating airway Fig 10 Williams airway intubator Fig 9 Patil-Syracuse oral airway Fig 11 Nasopharyngeal airways as an oral airway It is made of plastic and available in two sizes, number and number 10, which will admit up to an 8.0 or 8.5 internal diameter (ID) tracheal tube, respectively The tracheal tube connector should be removed during intubation, because it will not pass through the airway unless the airway is modified The proximal half is cylindrical, while the distal half is open on its lingual surface (Fig 10) A comparison of the Williams airway intubator with the Ovassapian fiberoptic intubating airway found that the Williams airway intubator provided a better view of the glottis in a significant number of patients.4 difficult to insert oral airway Other uses of nasal airway are during pharyngeal surgery, fiberoptic bronchoscopy, to apply CPAP and facilitate suctioning It is better tolerated in a semi-awake patient than an oral airway and is less likely to be accidentally displaced or removed (Fig 11) Nasopharyngeal Airway It is an alternative device that can be used to maintain the airway by inserting it through the nose It is useful in patients who have limited mouth opening or pathology of oral cavity that makes it 18.indd 219 Description Nasopharyngeal airways are made of soft plastic, polyurethane or latex rubber and have either a fixed or adjustable flange at its proximal end and a beveled distal end It curves to fit the curvature of the nasopharynx It is available in a range of lengths and internal diameters Insertion Technique The length of the airway needed for the patient is calculated as the distance from the tragus of the ear to the tip of the nose plus 219 8/19/2014 12:50:56 PM Section 5: Airway Equipment inch or the distance from the tip of the nose to the meatus of the ear After lubricating it along its entire length, it is held in the hand on the same side as it is to be inserted It is inserted through the nares, bevel end first It is passed vertically along the floor of the nose with slight twisting action and the curve of the airway should be directed toward the patient’s feet Do not proceed further if resistance is encountered Either it should be redirected or passed through the other nostril or a smaller sized airway should be used If placed appropriately, the pharyngeal end lies above the epiglottis and below the base of the tongue with the flange just outside the nostrils TYPES OF NASAL AIRWAY Bardex Airway It is made of rubber and has a large flange at the nasal end with bevel at pharyngeal end (Fig 12) Fig 12 Bardex nasopharyngeal airway Binasal Airway It consists of two nasal airways joined together by a connection that has a 15 mm adaptor for attachment to the breathing system The distal tips are near the larynx just below the tip of epiglottis (Fig 13) Cuffed Nasopharyngeal Airway The cuffed nasopharyngeal (pharyngeal) airway is similar to a short cuffed tracheal tube It is inserted through the nose into the pharynx After inflating the cuff, it is pulled back until resistance is felt Epistaxis Airway It is inserted into the nose and inflated It is useful in epistaxis by providing local pressure and is available in several sizes (Fig 14) Fig 13 Binasal airway Linder Nasopharyngeal Airway It is a clear plastic airway with a large flange The distal end is flat and not beveled It is supplied with an introducer which has a balloon that can be inflated and deflated by attaching a Luer syringe to the one way valve at the other end of the introducer (Fig 15) Rusch Airway It is made of red rubber It has an adjustable flange at the nasal end The pharyngeal end has a short bevel (Fig 16) Cuffed Oropharyngeal Airway 220 18.indd 220 It was invented by Robert Greenberg at the John Hopkins Hospital, Baltimore, Maryland in 1990, and can be as an alternative to the face mask use during spontaneous ventilation anesthesia (Fig 17) Fig 14 Epistaxis airway 8/19/2014 12:50:57 PM Chapter 18: Airways Description Fig 15 Linder nasopharyngeal airway It is color-coded according to sizes and is available in sizes 8–11 It is a modified Guedel type of oropharyngeal airway with an integral bite portion The proximal end has a standard 15 mm connector for attachment to the breathing circuit At its proximal end it has two posts for attaching a non-latex elastic fixation strap which is used to stabilize the COPA device in the mouth It is made of polyvinyl chloride (PVC) The inflatable cuff (capacity of 25–40 mL of air) at the distal end seals the oropharynx It is inflated through a one way valve attached to a pilot balloon which emerges at the tooth lip guard When inflated the cuff is broad and flattened posteriorly and shorter and more pointed anteriorly On inflation, it displaces the base of the tongue, forms a low pressure seal with the pharynx and passively elevates the epiglottis from the posterior pharyngeal wall to provide a clear airway.6 The cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (>90%); manipulations of the device may be required to maintain a patent airway.7 COPA is less reliable for “handsfree” ventilation than the laryngeal mask airway However, the incidence of laryngopharyngeal discomfort and salivation is less with the COPA.8 Precautions to Be Taken during Insertion of the Airway • • • Pharyngeal and laryngeal reflex should be depressed to prevent coughing and laryngospasm Appropriate size must be used The airways must be inserted after lubrication Problems of the Airway Fig 16 Rusch airway • • • • • • • • • Airway obstruction: If larger sized airway is used, it may act as an foreign body in the airway Epistaxis: Trauma to septal mucosa, nasal polyps or adenoidal tissue can cause epistaxis Trauma to the tongue, nose, uvula, pharynx and teeth Long oropharyngeal or nasopharyngeal airway can cause laryngospasm Latex allergy Tissue edema Ulceration and necrosis Central nervous system (CNS) trauma in a patient with basilar skull fracture Retention, aspiration or swallowing CONCLUSION Fig 17 Cuffed oropharyngeal airway 18.indd 221 Oral and nasopharyngeal airways constitute an important mandatory accessory in airway management 221 8/19/2014 12:50:57 PM Section 5: Airway Equipment REFERENCES Dorsch JA, Dorsch SE Understanding Anaesthesia Equipments, 5th edition Wolters Kluwer Health/Lippincott Williams and Wilkins; 2008 Capizzi F, Greenberg RS The Connell airway: a feasibility study AANA J 2001;69(6):473-5 Iqbal R, Gardner-Thorpe C, Thompson J, et al A comparison of an anterior jaw lift manoeuvre with the Berman airway for assisting fibreoptic orotracheal intubation Anaesthesia 2006;61(11):1048-52 Greenland KB, Irwin MG The Williams Airway Intubator, the Ovassapian Airway and the Berman Airway as upper airway conduits for fibreoptic bronchoscopy in patients with difficult airways Curr Opin Anaesthesiol 2004;17(6):505-10 Randell T, Valli H, Hakala P Comparison between the Ovassapian intubating airway and the Berman intubating airway in fibreoptic intubation Eur J Anaesthesiol 1997;14(4):380-4 Greenberg RS, Kay NH Cuffed oropharyngeal airway (COPA) helps in supporting the airway during fibreoptic tracheal intubation Br J Anaesth 1999;82(3):395-8 van Vlymen JM, Fu W, White PF, et al Use of the cuffed oropharyngeal airway as an alternative to the laryngeal mask airway with positive‐pressure ventilation Anesthesiology 1999; 90(5):1306-10 Heringlake M, Doerges V, Ocker H, et al A comparison of the cuffed oropharyngeal airway (COPA) with the laryngeal mask airway (LMA) during manually controlled positive pressure ventilation J Clin Anesth 1999;11(7):590-5 222 18.indd 222 8/19/2014 12:50:57 PM C hapter 19 Ventilating Systems— Manual Resuscitators Prerana N Shah Abstract Manual resuscitators are more commonly called as “artificial manual breathing unit (AMBU) bag” Their use is mostly confined to emergency scenarios of resuscitation and failure of anesthesia machine INTRODUCTION Nowadays, ventilating devices with nonrebreathing valves have a role in current practice during resuscitation or during transport of patient.1 Manual resuscitators are portable manual ventilating devices used for ventilating the patient during: • Resuscitation • Transport of the patient • As a standby measure for nonfunctioning of anesthesia machine • Administering anesthesia when anesthesia machine is not available, e.g in field situation They are known by many names, the most common being “AMBU bag”, i.e artificial mandatory breathing unit or air mask bag unit They are inflated at rest VARIOUS TYPES OF RESUSCITATORS • Laerdal resuscitator bag: most commonly used • AMBU bag resuscitator • Air-viva resuscitator • Samson Blease manual infant resuscitator The devices are available in three sizes: Adult: It delivers tidal volume of 600 mL and has a capacity of 1,600 mL It can be used in adults more than 30 kg weight Child: It has a capacity of 500 mL and can be used in patients weighing between kg and 30 kg Neonatal: It is capable of delivering the tidal volume up to 20–50 mL and can be used in infants up to kg The various components of any ventilating system are: • Self-inflating bag • Nonrebreathing valve • Bag refill valve • Attachment for oxygen enrichment 19.indd 223 • • Pressure limiting device for pediatric bags Attachment to the scavenging system if any Self-inflating Bag It is usually oval, cylindrical or shaped like a base ball It usually has a nonrebreathing valve at one end and a bag refill valve at the other end On release after squeezing, the bag expands If there is deficit in volume of oxygen to inflate the bag, it is compensated by intake of air The rate at which the bag reinflates determines the maximum respiratory rate Squeezing the bag requires considerable physical effort and during prolonged use the operator may become fatigued Also, size of the operator’s hands determines the actual tidal volume going to the patient and if the hands are small then it can cause hypoventilation It can also be folded to a smaller size to facilitate storage With prolonged exposure to cold conditions, the cycling rate of the bag may be reduced and the unit may become incapable of delivering satisfactory ventilation Nonrebreathing Valve It ensures unidirectional flow of air from the bag to the patient and from the patient to the atmosphere As the selfinflating bag is pressed, the valve directs the gas to the patient Simultaneously, the expiration port gets blocked When the squeezing of the bag is stopped and the bag is released, the expiration port opens and allows exhalation of the gases to the atmosphere Bag Refill Valve This is the inlet valve which allows entry of oxygen and air in the bag It is usually located on the opposite to the end of the nonrebreathing valve but can be at the same end also It is a 8/19/2014 12:51:18 PM Section 5: Airway Equipment one-way valve that is opened by the negative pressure inside the bag When the bag is squeezed, the valve closes automatically to prevent flow of the air back through the inlet Oxygen Enrichment Device The manual resuscitator can deliver fraction of inspired oxygen (FiO2) of at least 0.21 To increase the FiO2 oxygen has to be mixed with the air that is drawn from the atmosphere This can be achieved by delivering oxygen near the bag inlet valve or directly into the bag A tubing from the oxygen flow meter can be connected to the inlet nozzle of the manual resuscitator However, the oxygen enrichment is limited and can be enhanced by increasing the oxygen flow rate This has limitations because most of the flow meters cannot deliver oxygen above 15 L When delivered directly into the bag, delivery of higher concentration of oxygen can be achieved Laerdal Silicone Manual Resuscitator It has a laerdal fish mouth type of valve, air inlet and optional reservoir bag Delivered oxygen fraction depends on tidal volume, ventilator rate, oxygen flow rate, and type of reservoir and both the 250 mL and 500 mL corrugated tubes can be used as substitutes (Fig 1).2 AMBU Resuscitator It is a black colored self-inflating double ended with foam rubber lining It is available in two sizes It has an AMBU E2 nonrebreathing valve containing bobbin, disk, spring, steel ball; air inlet valve and oxygen inlet connection with or without attached oxygen reservoir (Fig 2) Reservoir When the bag is not filling, the continuous flow of air and/ or oxygen can be stored in a reservoir Open reservoir can be corrugated tubing that is placed around the inlet valve and is open to atmosphere Closed reservoir has an over flow and an air intake valve The inflation of the reservoir bag gives a visual impression whether it is receiving sufficient oxygen A deflated bag implies a defect in the bag or oxygen supply The bag should be capable of delivering an inspired oxygen concentration of at least 40% at the oxygen flow rate of 15 L/minute and at least 85% when an oxygen enrichment device is attached A positive end expiratory pressure (PEEP) valve or a scavenging device can be attached to the expiratory port Pressure Limiting Devices 224 19.indd 224 It is also called as pressure relief valve or pop-off valve It opens at an opening pressure of 45 cm of water for infant and pediatric bags and thus prevents lung injury because of barotraumas and also the gastric inflation In adults the opening pressure is kept at 60 cm of water The tidal volume delivered by a manual resuscitator to the patient depends on how the bag is pressed, the size of hands compressing, whether pressed with one or both hands and whether compressed against any solid surface The ventilatory rate will depend on how rapidly the bag re-expands When the bag is pressed the air or enriched air in the bag is delivered to the patient via the nonrebreathing valve Simultaneously, the inlet valve and the expiratory port of the nonrebreathing valve close During this period, if oxygen is attached and available, it will get collected in the reservoir When the bag is released, the negative pressure inside the bag will take in oxygen from the reservoir and from fresh gas flowing continuously in the inlet valve The delivered oxygen concentration is determined by minute volume, higher the minute volume lesser will be the oxygen concentration; the oxygen flow rate and the technique of bag squeeze Fig 1 Laerdal manual resuscitator Fig 2 Artificial mandatory breathing unit or air mask bag unit (AMBU) bag Part is the flexible mask to seal over the patients face Part has a filter and value to prevent pack flow into the bag itself Part is the soft bag element that is squeezed to expel air to the patient 8/19/2014 12:51:18 PM Chapter 19: Ventilating Systems—Manual Resuscitators Fig 3 Air-viva resuscitator Air-viva Resuscitator It is green colored, self-inflating single ended bag It is closed distally and has an oxygen nipple and an expiratory valve at the opposite end It causes partial rebreathing It cannot be used to give anesthesia (Fig 3) Samson Blease Manual Infant Resuscitator It has a bulb, body, face piece, oxygen inlet tube, air inlet holes, valve, and pressure regulating holes (Fig 4) Fig 4 Samson Blease manual infant resuscitator CONCLUSION Manual resuscitators continue to remain an essential component in the list of equipment mandatory in perioperative management REFERENCES Dorsch JA, Dorsch SE Manual Resuscitators In: Dorsch JA, Dorsch SE (Eds) Understanding Anesthesia equipments, 5th edition Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2008 Nam SH, Kim KJ, Nam YT, et al The changes in delivered oxygen fractions using Laerdal resuscitator bag with different types of reservoir Yonsei Med J 2001;42(2):242-6 225 19.indd 225 8/19/2014 12:51:19 PM C hapter 20 Accessories, Connectors, Bite Block, Magill’s Forceps, Stylet, and Laryngeal Sprays Prerana N Shah ABSTRACT In addition to the standard anesthesia machine, there are several additional equipment that are needed during the conduct of anesthesia Connector, dental block, Magill’s forceps, stylet and laryngeal spray are described below INTRODUCTION Accessories that are often needed and used with anesthesia equipment include connectors, dental block, Magill’s forceps, stylet and laryngeal sprays They should be available in the anesthesia cart CONNECTORS A connector, as the name implies, is accessory equipment that joins together two or more parts.1 However, one must distinguish it from an adaptor that is a special connector that joins functionally incompatible parts (Figs to 8) They can be differentiated by: • Shape (straight, right angle or elbow, T or Y) • Parts to which it is attached • Added feature (with nipple or pop-off ) • Size and type of fitting at either end (15 mm male, 22 mm female) Fig 2 Straight connector 15 mm female and 22 mm male connected to 15 mm female and 22 mm male Fig 1 Right angled (90°) connector—22 mm male and 15 mm female closed Fig 3 Right angled swivel connector 22 mm male and 15 mm female with clear silicone mm cap CHAPTER 20: Accessories, Connectors, Bite Block, Magill’s Forceps, Stylet, and Laryngeal Sprays Fig 4 Right angled swivel bronchoscope connector mm with suction cap Fig 7 Right angled Y-connector 15 mm female 22 mm male metal female Luer lock Fig 5 Catheter mount Fig 8 Right angled Y-connector 15 mm female 22 mm male with adjustable connectors All anesthesia systems end at the patient end by connection to a mask, supraglottic device or endotracheal tube (ETT) adaptor All face masks have a 22 mm female and a 15 mm male fitting To facilitate the change from mask to tracheal tube or supraglottic device and vice versa, a component having a 22 mm male fitting with a concentric 15 mm female opening to fit either a mask or a connector is used at the patient end of most of the systems It is usually right angled and may be called as elbow adaptor, elbow joint, elbow connector, face mask angle piece, mask adaptor or mask elbow.1 Bushings (Mounts) Fig 6 Straight Y-connector 15 mm female 22 mm male with 22 mm tube connection A bushing changes the internal diameter of a part It is usually cylindrical in shape and is inserted into and becomes part of, a pliable component such as a reservoir bag or a breathing tube (Figs and 10) 227 SECTION 5: Airway Equipment • • To allow flexibility between the tracheal tube or supraglottic device and the breathing system To increase the dead space, especially in cases of prolonged mechanical ventilation.1 Requirements of Connectors • • • 15 mm male fitting at the machine end and either 22 mm male/15 mm female fitting for connection to either tracheal tube or supraglottic device adaptor or a mask or 15 mm female fitting for connection to a tracheal tube adaptor Disadvantages of Connectors • • Fig 9 Bag bushing reduces 7–8 inches bag or tube to 15 mm female • They increase dead space (important in infants) Any addition of a connector increases the chances of possible disconnections Resistance increases markedly with sharp curves and rough side walls, e.g Cobb’s suction union, Rowbotham adaptors, corrugated and pliable metal connector etc To minimize it, use adaptors that are straight or have gentle curves Tracheal Tube Connector Fig 10 Connectors1 A swivel connector that can be used to insert a flexible fiberscope It has a flexible accordion-type side arm, A flexible metal connector that can be used between the tracheal tube and the breathing system It cannot be used with a mask, Straight connector with a side gas sampling port, Right angle connector for insertion of a flexible fiberscope It can accommodate different sized fiberscopes by changing the diaphragm The large cap is used if no diaphragm is present, Right angle connector with gas sampling port It is attached to the component of the breathing system The size of the connector is designated by the internal diameter (ID) of the patient end in millimeters The end that connects to the breathing system is called the machine end and has a 15 mm male fitting It is fitted with a tapered cone and is pushed into the lumen of the ETT It is slightly bigger than the tube so that the tube material has to be stretched to fit Various varieties include Magill’s oral curved, Magill’s nasal curved, Magill’s suction union, Magill’s Y-type pediatric, Cobb suction union, Rowbotham right angled (Fig 11), universal/ Nose worthy metallic or plastic, Carlen suction port, Robertshaw suction port, Swivel, Twin metallic (Fig 12), etc Magill’s connectors are smoothly curved with corrugations at the tracheal end and an expanded flange at the wider machine end The oral connectors are angled at slightly less than 90° while the nasal connectors have an acute angle curve Sleeves In contrast to a bushing, a sleeve alters the external diameter of a component Functions of Connectors and Adaptors • 228 • To increase the length of the circuit between the patient and the breathing system (head and neck surgery) To change the angle of connection between the tracheal tube or supraglottic device and the breathing system Fig 11 Rowbotham connector CHAPTER 20: Accessories, Connectors, Bite Block, Magill’s Forceps, Stylet, and Laryngeal Sprays BITE BLOCK A bite block is an accessory to protect the ETT, supraglottic device, fibreoptic scope, etc from getting damaged by the teeth It is also called as gag, mouth prop, bite protector (Fig 13).2 It is placed between the molar teeth or gums and not between the incisors It is less irritable than the oral airway It prevents the teeth from biting on a tracheal tube, supraglottic airway device, fiberscope, etc It is also used during electroconvulsive therapy (ECT) and in unconscious patients to prevent the teeth from biting the tongue and lips It also helps keep the mouth open for suctioning (Fig 14) An oral airway may be harmful to the patient as all the power of the bite is concentrated on the incisors, which are not designed for this pressure and are liable to break or loosen.2 Fig 12 Metal connector Pediatric Endotracheal Tube Connector Before standards were laid down, connectors were designed as per convenience (Magill’s connectors, 13 mm; Worcester, 12 mm; Metal Cardiff, 12 mm; Knight, mm; Bennett, 14 mm) Today, a standard 15 mm connection is supplied with most ETTs or supraglottic device They have higher resistance to flow even though they not have a bend in them because of the turbulence caused at the junction with the taper used for attachment to an ETT and is not the one with least resistance to gas flow Tapered Connection (Adaptors) They are used to join rigid tubes or other components so that the joint will not leak The joint is described as having a male half and a female half, which are pushed together with a slight twist to form a gas tight fit The joint can be easily dismantled and reassembled Current standard recommendations are: • 30 mm tapered connectors for scavenging hose • 22 mm tapered connectors within the breathing system • 15 mm connectors for ETT or supraglottic device Fig 13 Bite block Sterilization Most connectors available today are of disposable variety However, if they are not available, the nondisposable ones must be sterilized before every use Cleaning After use, they should be rinsed under running water, then placed in a solution of detergent and water and soaked Disinfection Rubber and plastic connectors may be sterilized with ethylene oxide or in a liquid, such, as gluteraldehyde Metal connectors may be boiled, autoclaved, or pasteurized Fig 14 Oberto mouth prop used for protecting the teeth during electro convulsive therapy 229 SECTION 5: Airway Equipment MAGILL’S FORCEPS Magill’s forceps is a common forceps that is essential constituent of intubation cart (Fig 15) Description It is a handheld, angled, nonlocking hinged in the middle type of forceps with flat grasping surface at the tip It is used for grasping and holding objects It employs the principle of the lever to grasp and apply pressure It is made of surgical steel and is designed so that when the grasping ends are in the axis of the tracheal tube, the handle is to the right During its use for intubation when the larynx is exposed, most of the forceps is out of the line of sight Uses • • • • It can be used to direct a tracheal tube into the larynx It can be used to direct a gastric tube or other device into the esophagus It can be used to insert or remove pharyngeal packing It can be used to remove foreign bodies from the upper airway or esophagus Problems The tracheal tube cuff may become damaged or perforated especially when forceps are used with high volume, low pressure cuffs Hence, the tube should never be grasped at the cuff There is also a risk of damaging the mucosa.3 The standard Magill’s forceps has been modified by changing the jaws of the forceps to give curved atraumatic parts without any serrations or sharp edges.3 Fig 15 Magill’s forceps 230 STYLET Stylet is a slender, stiff, long instrument that is usually inserted in the ETT to facilitate intubation (Fig 16) A stylet, also called as introducer when used fits inside and changes the shape of the tracheal tube to aid intubation It is also an essential constituent of intubation cart Many anesthesiologists routinely use it, while others use it for difficult intubation Description A variety of stylets are available Some have special nonstick surfaces There is usually a guard to limit the depth of its insertion so that it does not protrude out of the stylet during intubation It should be malleable so that its shape can be changed easily and rigid enough to maintain its shape during intubation It should have a smooth surface devoid of sharp edges It is also useful to check the patency of a tracheal tube The stylet may have a light at the end to assist in visualization during and after placement Prior to its use, it must be lubricated over its entire length and then inserted into the tube until the distal end reaches the bevel At this level, the guard must be fixed so that it cannot advance It is desirable to remove the connector from the tube before inserting the stylet The tube and stylet should then be bent to the desired shape, usually curved slightly for routine use and into a “J” or “hockey stick” shape for anterior larynx Once the tracheal tube passes beyond the vocal cords, it is withdrawn from the tube Problems It may be associated with trauma to the airway or esophagus especially if the tip protrudes from the patient end of the tube Fig 16 Stylet CHAPTER 20: Accessories, Connectors, Bite Block, Magill’s Forceps, Stylet, and Laryngeal Sprays LARYNGEAL SPRAYS Endotracheal intubation stimulates the sympathetic nervous system that causes a rise in arterial blood pressure If this is associated with light plane of anesthesia, laryngeal spasm can occur Local anesthetic applied to the vocal cords and trachea can limit this response There are various types of sprays (Fig 17) Macintosh® Spray It has a flexible tip to anesthetize the oral cavity and larynx for application of topical anesthesia (Fig 18) Forrester Spray It has a rigid curved spray nozzle designed for application of topical anaesthesia The bottle is below the level of the nozzle so that risk of siphoning is minimized (Fig 19) Fig 17 Laryngeal Spray Fig 19 Forrester laryngeal spray Fig 20 Swerdlow laryngeal spray Swerdlow Spray It has a rigid long nozzle designed for single handed application of topical anesthesia (Fig 20) For each Macintosh® spray device tested, the dose delivered by a single maximal hand squeeze of the atomizer bulb was variable and was not dependent upon the user A single, maximal hand squeeze of the Macintosh® laryngeal spray atomizer bulb can deliver a toxic dose of local anesthetic.4 After use, the spray must be washed with warm water otherwise crystals can get deposited in the nozzle and hamper its function Hence, before every use, it must be tested for its functioning and patent nozzle CONCLUSION Fig 18 Macintosh® laryngeal spray The above mentioned accessories constitute essential equipment especially in anticipated difficult intubation 231 SECTION 5: Airway Equipment REFERENCES Dorsch JA, Dorsch SE The Breathing System: General Principles, Common Components, and Classifications In: Dorsch JA, Dorsch SE (Eds) Understanding Anaesthesia equipments, 5th edition Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2008 Dorsch JA, Dorsch SE Face Masks and Airways In: Dorsch JA, 232 Dorsch SE (Eds) Understanding Anaesthesia equipments, 5th edition Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2008 Ehrensperger C, Gross J, Hempel V, et al [The modified Magill forceps] Anaesthesist 1992;41(4):218-20 Ing RJ, Craig DM, Nowosad A, et al Anaesthetic safety of the Macintosh® oral laryngeal spray device: original research South Afr J Anaesth Analg 2013;19(4):212-5 ... Mandar V Galande Anesthetic Breathing Systems 11 3 M Ravishankar 10 Anesthesia Ventilators Anila D Malde 12 4 Understanding Anesthetic Equipment & Procedures: A Practical Approach Section 5: Airway... DA Professor Department of Anesthesia Tata Memorial Hospital Mumbai, Maharashtra, India Mandar V Galande MD Clinical Assistant Fellow in Cardiac Anesthesia, Narayana Health Care Bengaluru, Karnataka,... Equipment & Procedures: A Practical Approach Anjana D Sahu MD Assistant Professor Department of Anesthesia Topiwala National Medical College and BYL Nair Hospital Mumbai, Maharashtra, India Amit