4 anesthesia mistakes you might not know you're making

Practicing anesthesia in veterinary patients can be challenging. Being young and healthy does not mean that a patient won't suffer an anesthetic complication or that less monitoring is required. And just because a geriatric or compromised patient makes it home does not mean that anesthesia was practiced as well as it could have been or that the patient isn't suffering from delayed complications. For example, clinical signs of renal failure, a common consequence of prolonged anesthetic hypotension, can take a couple of weeks to show.

This isn't meant to scare you away from using anesthesia but rather to direct your attention to practices that increase the potential for negative effects so you can avoid doing them. All patients deserve the safest anesthetic experience possible. Here are four common anesthesia-related mistakes that you might be making right now. Click here to read an additional mistake concerning dentistry. And click here to see how every team member has a role in providing safe anesthesia for all veterinary patients.

1. Relying too heavily on monitors.

Although machines are an important part of anesthetic monitoring, you can gather a lot of information with a hands-on approach. Technicians can get a fuller picture of anesthetized patients by consistently palpating pulses, assessing mucous membrane color and capillary refill times, feeling jaw tone, and tracking palpebral and withdrawal reflexes. These practices can also bring attention to concerns before a monitor sounds an alarm.

For example, an ECG can show a normal tracing for up to five minutes after cardiac arrest has occurred. Monitors can give inaccurate readings for many reasons such as movement or shifting of a probe, an inappropriately sized or inflated cuff, extremes, loose wires, and improper set-up. An astute technician can often determine if the monitor is correct.

2. Administering too little anesthetic and analgesic drugs.

Most anesthetic and analgesic drugs have ranges rather than a specific dose because patients' anesthetic needs differ based on their history, manner, physical health status, and the procedure being performed. Some technicians and veterinarians try to play it safe by administering the lowest dose in the range, which can be effective, but inadequate premedication may create a need for increased doses of induction agents such as propofol. (Note: Check your state's practice act for guidelines about the level of supervision required for credentialed technicians to administer anesthesia.)

Propofol causes dramatic respiratory depression, and a patient may wake up during surgery and require repeated propofol doses or inhalant anesthesia. Properly dosing combinations of drugs, such as analgesics and tranquilizers, can be effective and safe and can greatly reduce the amount of anesthetic induction and maintenance drugs needed. For example, hydromorphone's dose range is 0.05 to 0.2 mg/kg, but 0.05 mg/kg will not likely provide proper analgesia for a patient undergoing an orthopedic procedure. So 0.15 mg/kg is an appropriate dose, especially when combined with a low dose of acepromazine (0.02 to 0.05 mg/kg), when the patient is not geriatric and has no known potential for complications.

3. Thinking anesthesia and analgesia are interchangeable.

The veterinary profession has progressed dramatically over the past several years in regard to pain management, and analgesia is now considered the standard of care for in-hospital patients as well as for those being discharged. Patients can still feel pain while anesthetized, and the initial response when a patient's heart rate increases or the patient reacts to surgical stimulation is often to increase the amount of anesthetic agent administered. But inhalants don't have analgesic properties, and neither does propofol.

Hydromorphone is an effective analgesic and a great drug to use as a premedication, but its efficacy can be as short as two hours. Often patients are still undergoing surgery at that time. Intraoperatively, readministering analgesic drugs or starting a constant-rate infusion can be more effective and beneficial than increasing the anesthetic agent.

4. Giving drugs without knowing their mechanisms and potential side effects.

Any time a drug is prescribed or administered, everyone involved should be aware of the drug's effect and any potential side effects. An example of a misunderstood medication is dexmedetomidine. Many fear giving it because it causes pale mucous membranes and bradycardia, which are usually signs of cardiovascular compromise. A common reaction to bradycardia is to administer anticholinergics, which are contraindicated. Dexmedetomidine, an alpha-2 agonist drug, causes arterioles to constrict and raise the patient's blood pressure. Because of this rise in blood pressure, there is a reflexive bradycardia to compensate.

If the blood pressure is preserved in a normal range, then the slowing of the heart rate isn't detrimental to cardiac output and the patient is not in danger. However, forcing the heart to speed up when under the influence of dexmedetomidine causes a marked increase in myocardial oxygen demand and work, which can be detrimental to the patient. If the patient appears to be suffering negative effects from this drug, the recommended treatment is to reverse it with atipamezole or administer fluid boluses.1

Another misunderstood drug is propofol. Many consider propofol to be safe and administer it liberally to compromised animals because it metabolizes quickly. However, propofol is a severe respiratory depressant and should be administered cautiously or even avoided in compromised patients. Adequate premedication and the administration of a tranquilizer, such as diazepam or a fentanyl bolus, on induction can greatly reduce the amount of propofol given and, thus, decrease the potential for anesthetic complications.

For many years, acepromazine was considered dangerous in animals with seizure potential since it was thought to decrease the seizure threshold. That has since been proven to be erroneous, and many neurologists give it to seizure patients as a sedative during the postictal phase. Its use in anesthesia has decreased over the years because it can cause hypotension and splenic enlargement, but these risks are minimized with low doses (0.02 to 0.05 mg/kg). It can be a beneficial drug to add to a clinic's drug supply because it has a synergistic effect with opioids.

Avoiding these four practices should help reduce the amount of negative anesthetic experiences in your practice. However, nobody is perfect. If you do make a mistake, it is imperative to bring it to the doctor's attention as soon as you recognize it so proper action can be taken. Trouble ensues and patients suffer when you do not tell anyone about a mistake. Treat mistakes as learning experiences by looking at what brought them about and enacting policies to prevent them from happening again.

Jennifer Keefe, CVT, VTS (ECC, anesthesia), is anesthesia supervisor at Angell Animal Medical Center in Boston, Mass.

REFERENCE

1. Moses L. Use of glycopyrrolate contraindicated with Domitor. Circulated at Angell Memorial Animal Hospital, Boston, Mass: 2006.