Veterinary Anesthetic and Monitoring Equipment

Kristen G. Cooley, Rebecca A. Johnson, Kristen G. Cooley, Rebecca A. Johnson

• Publisher: Wiley-Blackwell
• Year: 2018
• Print ISBN: 9781119277156
• eBook ISBN: 9781119277163
• Edition: 1
• Topic: Medicine
• Subtopic: Veterinary Medicine

Veterinary Anesthetic and Monitoring Equipment is the first veterinary-specific resource solely dedicated to anesthetic and monitoring equipment used in clinical practice.

• Offers a practical guide to anesthetic and monitoring equipment commonly used in veterinary medicine
• Provides clinically oriented guidance to troubleshooting problems that may occur
• Discusses general principles applicable to any equipment found in the practice
• Presents information associated with novel anesthetic equipment and monitors

1
Medical Gas Cylinders and Pipeline Systems

Carl Bradbrook

European Specialist in Veterinary Anaesthesia & Analgesia, Consultant Veterinary Anaesthetist, ACE Vets Ltd, Rossett, UK

1.1 Medical Gas Cylinders

Gas cylinders are used to store and supply medical gases to clinical areas of the veterinary hospital, including anesthetic machines, mechanical ventilators and surgical instruments. Cylinders are attached, either directly or using a pipeline and distribution system to the anesthetic machine or outlet. Cylinders are available in a number of sizes, described by the letters A–J. Their designated letter is dependent on their size; A is the smallest and J the largest (British Oxygen Company 2016). The size used is dependent on the intended use and region of the world. For example, in the United Kingdom (UK) and European Union (EU), the most commonly used sizes are E, F and J, whereas in North America, E and H are more usual. Table 1.1 details the sizes and volumes of the these cylinders.

Table 1.1 Gas cylinder dimensions and capacity.

	UK				US
	E	F	G	J	E	F	G	H
Dimensions (inches)	34 × 4	36 × 5½	54 × 7	56½ × 9	26 × 4½	51 × 5½	51 × 8½	51 × 9¼
Oxygen (L)	680	1360	3400	6800	650	2062	5300	6900
Nitrous oxide (L)	1800	3600	9000	18 000	1590	5260	13 800	15490

Cylinders are available containing a number of different medical gases. The medical gases most used in veterinary practice include oxygen, nitrous oxide and medical air, although carbon dioxide may also be found in certain situations. For example, carbon dioxide is used for body cavity insufflation during minimally invasive procedures.

1.1.1 Gas Pressures

A pressure gauge, most commonly of the Bourdon type (Figure 1.1), should be associated with the cylinder connection to the system. A Bourdon gauge consists of a coiled tube that changes shape, dependent on gas pressure. As the coil changes shape, an attached pointer moves over the scale to display the pressure (Davis and Kenny 2007). The gauge reads the pressure generated within the cylinder or pipeline distribution system, dependent on the amount of gas or vapor supplied. The term “gas” is used to describe the contents of a cylinder containing a non‐liquefied compressed gas. Examples include oxygen and medical air (Davis and Kenny 2007). The cylinder contents are present in this state when the gas does not change into a liquid at room temperature regardless of pressure applied, since room temperature is above the critical temperature of gas. The critical temperature is the temperature above which a substance cannot be liquefied, regardless of the pressure applied. The term “vapor” is the gaseous state of a substance when, at ambient temperature, it is present below its critical temperature (Davis and Kenny 2007). The liquid phase is present in the cylinder with the vapor phase remaining on top; nitrous oxide is an example of a medical gas stored in this state.

Figure 1.1 Left: Interior schematic of a Bourdon type pressure gauge including the expandable copper tubing and pointer. Right: Example of a common Bourdon gauge routinely located on an anesthetic machine.

The International System of Units (SI) used for pressure is the pascal (Pa) which, for convenience, is commonly expressed as kilopascal (kPa). However, conversion to other commonly used pressure units is frequently performed and is as follows:

(1.1)

1.1.2 Medical Gases

Oxygen and medical air are stored as compressed gases (Highley 2009; Westwood and Rieley 2012), whereas nitrous oxide and carbon dioxide are stored as a liquid with a vapor phase above. The gauge pressure will depend on the particular gas. For example, those stored as compressed gases will have a gauge pressure that is directly related to cylinder contents at all times, whereas t...

Table of contents

• Cover
• Table of Contents
• Dedication
• List of Contributors
• Preface
• 1 Medical Gas Cylinders and Pipeline Systems
• 2 Oxygen Concentrators
• 3 Small Animal Anesthetic Machines and Equipment
• 4 Large Animal Anesthesia Machines and Equipment
• 5 Anesthetic Vaporizers
• 6 Anesthetic Ventilators
• 7 Humidification and Positive Pressure Equipment
• 8 Waste Anesthetic Gas Collection and Consequences
• 9 Hazards of the Anesthetic Delivery System and Operating Room Fires
• 10 Components of the Breathing System
• 11 Mapleson Breathing Systems
• 12 The Circle System
• 13 Laryngoscopes
• 14 Supraglottic Airway Devices and Tracheal Tubes and Stylets
• 15 Oxygen Delivery Systems
• 16 Gas Monitoring
• 17 Airway Volumes, Flows and Pressures
• 18 Pulse Oximetry
• 19 Cardiovascular Monitoring
• 20 Electrocardiography
• 21 Neuromuscular Transmission Monitoring
• 22 Temperature Regulation and Monitoring
• 23 Fluid Regulation and Monitoring
• 24 Anesthetic Records
• 25 Equipment for the Magnetic Resonance Imaging System
• 26 Equipment for Environmental Extremes and Field Techniques
• 27 Equipment Checkout and Maintenance
• 28 Equipment Cleaning and Sterilization
• 29 Unique Species Considerations: Dogs and Cats
• 30 Unique Species Considerations: Ruminants and Swine
• 31 Unique Species Considerations: Equine
• 32 Unique Species Considerations: Avian
• 33 Unique Species Considerations: Rabbits
• 34 Unique Species Considerations: Rodents
• 35 Unique Species Considerations: Fish and Amphibians
• 36 Unique Species Considerations: Reptiles
• 37 Unique Species Considerations: Non‐Human Primates
• Index
• End User License Agreement