Oops-anesthetic accidents: prevention and response (Proceedings)

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Oops-anesthetic accidents: prevention and response (Proceedings)

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Nov 01, 2010

Anesthetic mishaps can lead to patient morbidity and mortality. Most problems anesthesia-related problems can be prevented by advanced planning, training, patient monitoring, and the development of standard operating protocols.

Anesthesia-associated mortality:

Pet owners expect their veterinarians to choose safe anesthetic protocols, use functional anesthesia equipment, monitor their animals while anesthetized, and prevent and treat pain associated with diagnostic or therapeutic procedures. Over the past decade, technology to anesthesia monitoring and our understanding of physiology and pharmacology has advanced rapidly. Unfortunately, the actual practice of veterinary anesthesia has not evolved quite as rapidly. Thus, it is not surprising that anesthetic mortality in animals is higher than seen in human beings. A recent study in small animals reported that overall risk of anesthesia and sedation-related death was 0.17, 0.24, and 1.39% in dogs, cats, and rabbits (Vet Anes Analg 2008). The risk in 'healthy' animals was ~0.05%. This is better than the risk reported for horses (0.9%) but much worse than reported for human beings (~ 0.0075%). Here are a few findings of interest:
     • More than one-half of all anesthetic-related mortalities occurred in the postoperative period.
           o Could increased postoperative monitoring decrease mortality?
     • Sick animals are more likely than healthy animals to suffer an anesthetic-related death
           o ASA status 3-5: The ASA Classification system does help to stratify risk
           o How should we alter anesthetic management for sick animals?
     • Cats have higher anesthetic-related mortality than dogs (even 'healthy' ASA 1-2 animals)
           o Smaller
           o difficult to monitor
           o easily stressed
           o physiological differences
     • Risk for anesthetic death in small animals appears to be decreasing
           o Better drugs?
           o Better monitoring?
           o Better training?
     • Animals given sedation alone MAY be at decreased risk compared to anesthetized animals.

Other studies in veterinary medicine have shown:
     • monitoring decreases mortality
     • alpha two agonists may increase mortality
     • acepromazine may decrease mortality.

Preanesthetic Assessment:

Attention to signalment, history, physical examination and laboratory findings may be useful in minimizing anesthesia-related problems. The following is a list of common problems that should be associated with an adjustment in management:
     • Breed issues
     • Heart Disease (especially when patient is in failure)
     • Renal failure
     • Liver disease
     • Neurologic disease

Anesthesia Equipment:

Anesthesia equipment used in veterinary medicine today is generally simple and reliable. However, safe use requires an understanding of the principles of operation and effects of anesthetic drugs. Moreover, regular maintenance is important to insure reliable machine operation.
          • Common sources of problems include:
          • One-way valve operation
     • Leaks
     • Oxygen supply
     • Pressure-relief valve
     • Disconnections

Patient Monitoring:

Monitoring of patient well-being is important to recognizing anesthetic-related problems before they lead to morbidity or mortality. Assigning a trained individual to assess patient well-being is probably the most important part of veterinary anesthetic management.

The advantages and disadvantages of specific monitoring tools will be discussed:
     • Pulse oximetry
     • Capnography
     • Blood pressure monitoring