How to reduce anesthesia risk

One of the biggest concerns for pet owners when it comes to surgery for their pets is anesthesia.  

Anesthesia has become a common routine procedure in daily clinical practices, but strict protocols must still be thoroughly followed to avoid potential complications. Among the possible complications on an anesthetized animal, we can find regurgitation or vomiting as the main risks, as these could cause aspiration pneumonia caused by inhaling vomit, hence creating a severe problem for our pet.  

For this reason, one of the main factors to reduce the risk of these adverse effects is to ensure proper fasting:  

The preoperative fasting period should be between 8 and 12 hours, preferably either serving them wet food as the last meal (easier to digest) or providing half the portion of their usual meal. Omeprazole can also be administered the night before to anticipate possible gastric reflux. In puppies, fasting should not exceed 6 hours due to the risk of hypoglycemia, among other complications.  

It is also counterproductive if fasting exceeds 12 hours, as it increases stomach acidity and could cause gastric ulcers or esophagitis.  

Water can be administered up to 2 hours before anesthesia.  

Once the patient is at the veterinarian’s clinic, an evaluation of the animal is performed, indicating things such as medical history, age of the animal, weight, breed, if they are on any treatment, and most importantly if they have recently had any cardiovascular or gastrointestinal disorders. Another observation is that obese dogs and some specific breeds are more predisposed than others to vomiting and regurgitation during anesthesia, having therefore a higher risk.  

Next, a physical examination is conducted, paying particular attention to hydration status, body condition, color of the mucous membranes, and observations from cardiac and pulmonary auscultation.  

Additionally, at least one blood catheter will be placed to have direct access to the vein and be able to administer medications or fluid therapy if necessary quickly.  

Pre-anesthetic analyses will help us see if there is any pre-existing pathology that could increase the anesthetic risk of our animal, mainly in those over 8 years old.  

Subsequently, and based on all of the above, the animal will receive an anesthetic risk assessment (ASA scale) depending on the surgery to be performed. With all this information, an anesthetic medication protocol is carried out to help avoid future problems.  

The medication protocol includes initially a pre-medication in which we administer analgesia and sedation. Subsequently, induction is carried out, usually with Propofol, which facilitates intubation of the animal to administer anesthetic gases such as Isoflurane, which is maintained throughout the surgery.  

It is essential to intubate the animal to protect the airway and keep the endotracheal tube balloon inflated until the moment of extubation to avoid pneumonia in case of regurgitation. Repositioning the animal on the operating table can also be a risk factor.  

A multiparameter monitor is also necessary to monitor the patient at all times and detect any danger.  

In emergency cases, when an animal must urgently enter the operating room, regurgitation, and aspiration must be prevented by administering antiemetics, Omeprazole, and prokinetics such as Metoclopramide. Since they cannot be properly stabilized, these emergency surgeries usually have the highest anesthetic risk.  

The good news is that, according to the most recent studies, anesthetic mortality is decreasing, making the recovery period the most critical moment. 

Míriam Rodríguez
Vet
Lliga per a la Protecció d’Animals i Plantes de Barcelona