Small Animal Anesthesia and Pain Management

A Color Handbook

Jeff C. Ko, Jeff C. Ko, Jeff Ko

• Publisher: CRC Press
• Year: 2018
• ISBN:
  9781351967785
• Edition: 2
• Topic: Médecine
• Subtopic: Médecine vétérinaire

3* Doody's Review!

This concise quick reference guide has been thoroughly updated in its second edition. It remains clinically focused, based on experience underpinned by published research data.With 18 brand new chapters on topics ranging from perioperative blood works and urine analysis to light therapy in pain management and rehabilitation, the book covers anesthetic equipment, monitoring, premedication, intravenous induction agents, injectable anesthetic combinations, inhalant anesthesia, anesthesia for specific diseases, fluid therapy, anesthetic emergencies and complications, acute and chronic pain management. Nine new chapters address anaesthetic considerations for different surgeries.

Drug dosages and anesthetic protocols are provided in tabular form. New to this edition are chapters covering anesthesia considerations for specific conditions and diseases, including

• 
  
  

• perioperative blood works and urine analysis

• 
  
  

• blood transfusion medicine

• 
  
  

• anesthetic considerations and interpretations

• 
  
  

• rehabilitation and pain management for chronic pain patients

• 
  
  

• pain management of oncologic pain and radiation therapy

• 
  
  

• acupuncture and herbal medication for acute and chronic pain and

• 
  
  

• low level light therapy in pain management.

Containing over 300 color illustrations, Small Animal Anesthesia and Pain Management is ideal for all those who need practical information easily to hand: small animal practitioners, veterinary technicians/nurses, and veterinary students.

CHAPTER 1

Equipment for inhalant anesthesia

Jeff C Ko

Introduction

Components of the anesthesia machine

Breathing circuits and components

Modern human anesthesia machines for veterinary use

Selecting a breathing circuit

Ambu bags

Ventilators

Oxygen flow rates

Endotracheal tubes

Laryngeal mask airway for cats

Laryngoscopes

Induction chambers and face masks

Checking the accuracy of the flowmeter

Checking the anesthesia machine and breathing circuit for leaks

Checking the scavenging system for leaks and malfunctions

Monitoring of waste gas and pollution

Further reading

Introduction

Inhalant anesthetic equipment includes an anesthesia machine and a breathing circuit (Figs. 1.1, 1.2). Other important equipment for inhalant anesthesia includes a reservoir bag, endotracheal tube, laryngoscope, and blade, as well as oxygen and other medical gases. The purpose of the inhalant anesthesia machine, together with the breathing circuit, is to deliver oxygen and inhalant anesthetic effectively to the animal and to remove carbon dioxide (CO₂) from the animal’s respiratory system. This chapter describes the primary components of inhalant anesthetic equipment and their functions.

Fig. 1.1 An anesthesia machine (portion outlined with the green color box) with a rebreathing circuit (portion outlined with the red color box) and an isoflurane vaporizer-out-of-the-circuit. The acronym for the five basic components (FROGS) is marked on the image. The rebreathing circuit has a pair of breathing hoses and a CO₂ absorbent.

Fig. 1.2 An anesthesia machine (portion outlined with the green color box) with a non-rebreathing circuit (portion outlined with the red color box). The acronym for the five basic components (FROGS) is marked. Note the simple structure of a non-breathing circuit, which is built to have minimal resistance to breathing.

Components of the anesthesia machine

No matter how simple or complicated an anesthesia machine looks, it has five basic components (Flowmeter, Regulator, vapOrizer, Gas supply, Scavenger), which can be remembered using the acronym FROGS.

FLOWMETERS (FIGS. 1.3, 1.4)

Figs. 1.3, 1.4 Two sets of flowmeters each with a rotameter and a needle valve at the bottom (Fig. 1.3); note the nitrous oxide (blue color) and oxygen (green color) each has their own set of flowmeters. Note the metal bar in front of the rotameters to prevent accidental adjustment of the flowmeters. Pediatric flowmeters (on the left side, 1.4) are graduated in milliliters from zero to 1,000 ml, while adult flowmeters (on the right side, 1.4) are graduated in liters.

Key points about flowmeters:

• The flowmeter is used to control precisely the delivery of a specific amount of medical gas through the vaporizer to the patient.
• A flowmeter is required for each medical gas.
• There are two types of flowmeter: pediatric and adult (Fig. 1.4). A pediatric flowmeter provides more precise control of the flow rate and allows the anesthesia machine to run with a precise, low flow rate. It is therefore preferred for running a low-oxygen flow rate.
• The flow rate is determined by observing the position of the bobbin or float in the flowmeter. The bobbin or float comes in various shapes and sizes. Ball-shaped bobbins are read at the center or widest diameter of the float (Fig. 1.5). Bobbins with other shapes are read at the top of the float (Fig. 1.6).
  
  Figs. 1.5, 1.6 Oxygen enters the rotameter and passes through a bobbin (float), exiting at the top of the flowmeter to enter the machine and vaporizer. Ball-shaped bobbins are read at the center or widest diameter of the bobbin (1.5). Other shapes of bobbins are read at the top of the bobbin (1.6). Note that the flowmeter is tapered in shape. The clearance between the bobbin and the wall of the flowmeter increases from bottom (narrow) to top (wide).
  
• Flowmeters are agent specific and color coded (Fig. 1.3). For example, in the USA, flowmeters for oxygen are coded green, while flowmeters for nitrous oxide are coded blue and medical room air flowmeters are coded yellow. This may not be the same in other parts of the world.

REGULATORS (PRESSURE REDUCING VALVES)

Key points about regulators:

• The pressure regulator, also called a pressure reducing valve, is designed to reduce the high pressure from the medical gas, which is supplied from a portable or storage tank (up to 2,200 psi [15,168.4 kPa] in a size E portable oxygen tank, Fig. 1.7), to a working pressure (15–30 psi [103.4–206.8 kPa]) that does not damage the anesthesia machine or the patient’s airway.
  
  Fig. 1.7 This pressure gauge indicates a partially full size E oxygen tank of approximately 1,350 psi (9308 kPa). A full size E oxygen tank has a pressure of approximately 2,200 psi (15,168.4 kPa). A quick way to calculate the amount of oxygen (in liters) left in the size E tank is to multiply the pressure in psi by 0.3. So, in this case there are 405 liters of oxygen left in the tank. Note the regulator (brass color) located directly below the pressure gauge. Regulators (and flowmeters) are marked with the corresponding medical gas color.
• The regulator provides a constant flow of gas irrespective of measured changes at the source.
• Given that each medical gas requires a specific regulator, there is one regulator for each medical gas within the anesthesia machine.

VAPORIZERS

Key points about vaporizers:

• A vaporizer (Fig. 1.8) is used to add a specific amount of inhalant anesthetic agent to the oxygen/gas (nitrous oxide) mixture in order to anesthetize the patient. The amount of inhalant anesthetic is expressed either as a percentage of the saturate vapor added to the oxygen/gas flow or as a volume percentage of the vapor output.
  
  Fig. 1.8 A desflurane vaporizer (left), a Tec 4 isoflurane vaporizer (middle with purple color label), and a Tec 4 halothane vaporizer (on the right with the red label). Note the electric cable and plug on the desflurane vaporizer for the external heat supply required for proper vaporization.
• Because anesthetic gas (isoflurane or sevoflurane) can vaporize to dangerously high concentrations (isofluran...

Table of contents

• Cover
• Title Page
• Copyright Page
• Contents
• Preface
• Acknowledgments
• Contributors
• Abbreviations
• CHAPTER 1: Equipment for inhalant anesthesia
• CHAPTER 2: Perioperative blood work and urine analysis
• CHAPTER 3: Preanesthetic medication: drugs and dosages
• CHAPTER 4: Intravenous injection techniques and intravenous anesthetic agents
• CHAPTER 5: Inhalant anesthetic agents
• CHAPTER 6: Anesthesia monitoring and management
• CHAPTER 7: Fluid therapy
• CHAPTER 8: Blood components and transfusion therapy
• CHAPTER 9: Injectable sedative and anesthesia–analgesia combinations in dogs and cats
• CHAPTER 10: Anesthetic considerations for specific diseases
• CHAPTER 11: Airway management and ventilation
• CHAPTER 12: Anesthetic considerations for patients requiring upper airway surgery and patients requiring thoracic surgery
• CHAPTER 13: Anesthetic considerations for upper and lower gastrointestinal endoscopic procedures
• CHAPTER 14: Anesthetic considerations for minimally invasive surgical procedures
• CHAPTER 15: Anesthetic considerations for neurologic patients
• CHAPTER 16: Anesthetic considerations for ophthalmic surgeries
• CHAPTER 17: Anesthesia and sedation for radiography, ultrasound, CT, and MRI patients
• CHAPTER 18: Anesthetic considerations for orthopedic surgical patients
• CHAPTER 19: Anesthetic considerations for dental and oral–facial surgeries
• CHAPTER 20: Analgesia and sedation of emergency/intensive care unit patients
• CHAPTER 21: Anesthetic emergencies and cardiopulmonary resuscitation
• CHAPTER 22: Perioperative cardiac arrhythmias and treatments
• CHAPTER 23: Local anesthetic agents and anesthetic techniques
• CHAPTER 24: Acute pain management
• CHAPTER 25: Photobiomodulation therapy in pain management
• CHAPTER 26: Management of neuropathic pain in dogs and cats
• CHAPTER 27: Oncologic pain management and radiation therapy
• CHAPTER 28: Chronic pain management for osteoarthritis in dogs and cats
• CHAPTER 29: Acupuncture and Chinese medicine for pain management in dogs and cats
• CHAPTER 30: Rehabilitation and pain management for veterinary patients
• CHAPTER 31: Anesthesia in shelter medicine and high-volume/high-quality spay and neuter programs
• CHAPTER 32: Euthanasia
• APPENDIX: Anesthetic dosage reference ranges
• Index