Did you know that February 9th is National Toothache Day? No, really. It’s a thing. Along with National Toothache Day, American Heart Month, Black History Month, Valentine’s Day, and Creative Romance Month (again, it’s a thing), February boasts the AVMA-sponsored National Pet Dental Health Month. It’s a time when many pet owners schedule their pet’s annual checkup. Now is a perfect time to review ways to meet some of the challenges that come with anesthetizing pets for dental procedures. At the end of this post, and interspersed throughout it, you’ll find links to more information that you might find useful.
Veterinary anesthesia is always improving and is safer now than it ever has been. But we can’t dismiss our clients’ concern about the risks of anesthesia for dentistry. After all, they are not unfounded. In a two-year study of nearly 200,000 pets, dental procedures ranked number three as a surgical procedure likely to result in death. Patient age, underlying systemic disease, length of anesthesia, and hypothermia are listed among probable contributors to the greater anesthetic risk among dental patients. Of those contributors, we have most control over preventing hypothermia. Studies show that 84% of anesthetized dogs and 97% of anesthetized cats experience hypothermia. These studies clearly indicate hypothermia is one of the most predictable complications of anesthesia, and veterinary staff needs to be proactive in preventing heat loss and to monitor body temperatures continuously.
Preventing hypothermia has traditionally focused on skin warming and conserving body surface heat, but remember the margin of safety from causing significant thermal injury is surprisingly narrow in animals. Skin can be burned from devices supplying constant surface heat of as little as 115°F for one hour. Hot tap water can be warmer than that. Here are some tips for safely warming dental patients suggested by Portland’s award winning veterinary hospital and training facility, DoveLewis.
- Place the patient on a solid surface like a mat. Laying a patient on a towel over a water table provides more surface area to lose body heat.
- Place the patient on any type of approved heating pad.
- Bubble wrap layers over the patient to help retain heat
- Baby socks on their feet retains heat
- An emergency reflective blanket tented over the patient traps heat
- Attempt to keep the head as dry as possible and take time to wipe it dry periodically.
Breathing cold oxygen from an anesthetic gas machine can be a major contributor to cooling anesthetized patients, especially in the early stages, right after intubation. Normally the nose and pharyngeal mucosa transfer heat and moisture to inspired air and then recover much of the heat during expiration. An endotracheal tube bypasses the nose and pharyngeal mucosa and delivers cold gases directly into the lungs. That leaves no chance of temperature recovery during exhalation. This costs a 25 pound dog nearly 3000 calories of warming energy in the first hour of anesthesia alone. Warming the inspired gases to near normal body temperature and delivering it from the moment of intubation is a great way to prevent the loss of core body temperature caused by the body’s attempt to warm cold inspired gases. It literally warms from within.
The first heated breathing circuit for veterinary use was introduced to the United States in 2013 by Advanced Anesthesia Specialists of Australia. These heated circuits have a heating element embedded into the tubing of the inspiratory limb of the breathing circuit. A sensor molded in the tubing at the Y piece monitors gas temperature and a microprocessor controls heating. Closed-loop feedback is provided by a patient temperature probe which enables the microprocessor to monitor the animal’s body temperature and it turns off the heater if either sensor detects temperatures above the presets. The heated circuit is distributed by DarvallVet in North America. Heated breathing circuits offer a new way to capture control of a dental patient’s body temperature from the moment of intubation, and puts an effective new tool in your hypothermia-management toolbox.
In addition to surface warming with an approved veterinary warming device (for instance a warm air blanket system) and the use of a heated breathing circuit, there are other ways to protect your patients from losing body heat. High oxygen flow rates are not only expensive and an inefficient use of anesthetic gases, they also rapidly siphon body temperature from your patient. Selecting a circle system rather than a non-rebreathing, and then running the circle system at a lower oxygen flow rate is an excellent way to prevent heat loss from your patient. Visit the DarvallVet website to learn more ways to help keep your patients warm before, during, and after anesthesia or give them a call at 866-931-3292 to discuss any of your anesthesia challenges. Their anesthesia staff has over 35 years’ experience as animal anesthetists.
Here’s a list of additional referenced posts on this subject (click title to view):
- Nerve Blocks for Veterinary Oral Surgery
- Top 5 Anesthetic Complications
- Rebreathing or Non-rebreathing?
- Hypothermia and the Veterinary Dental Patient
- Go With The Flow – How to decide the oxygen flow rate for small animal anesthesia
- Effective Patient Warming
Ken Crump AAS, AHT is a writer and animal anesthetist, and writes Making Anesthesia Easier for DarvallVet, a division of Advanced Anesthesia Specialists. He makes dozens of Continuing Education presentations on veterinary anesthesia and oncology across the United States and in Canada. Ken retired from the Veterinary Teaching Hospital at Colorado State University in 2008.