Anesthesia monitoring: Part I (Proceedings)


Anesthesia monitoring: Part I (Proceedings)

Apr 01, 2009

• The word anesthesia means without sensation-–our goal is to provide unconsciousness, amnesia, analgesia and muscle relaxation for a variety of procedures both invasive and non-invasive. Our ability to carefully string our patients out along the line between life and death compromises homeostasis making close monitoring essential.

Why monitor?

• Anesthetic emergencies are difficult to predict

• Anesthetic emergencies happen quickly

• Anesthetic emergencies can be devastating

• It is better to be proactive rather than reactive

Our goal

• To be able to walk that line with confidence by maximizing the safety of the anesthetic experience

Morbidity and mortality (M&M)

• Morbidity refers to the prevalence of disease (related to the anesthetic event in this case)

• Mortality refers to the chances of death

• Certain problems are more likely to increase M&M

o Excessive bradycardia

o Cardiac depression

o Vasodilation

o Hypotension

o Arrhythmias

o Hypoventilation

o Hypoxemia

o Hypothermia

• Diligent monitoring allows us to recognize and treat potentially life threatening problems

Monitoring basics

• If you only had eyes, ears and hands...

o Heart rate

o Pulse quality and vasomotor tone

o Respiratory rate and character

o Reflexes and muscle tone

o Eye position

o Body temperature

• Monitoring multiple parameters gives you a more complete picture of the physiologic status of the patient

Heart rate

• Stay away from extremes...

• Bradycardia

o Heartrate is too slow when it is associated with decreased cardiac output, hypotension and/or poor perfusion

o Dog low 50's (with normal BP- also dependent on size, small dogs have higher heart rates...)

o Cat low 100's (with normal BP)

o It is also important to monitor blood pressure (BP) and end-tidal carbon dioxide (ETCO2)

• Tachycardia

o Decreases filling time of ventricle and increases myocardial oxygen consumption- a double whammy!

o Dogs 180-200 (size dependent)

o Cats 240-280 (size dependent)

• Some cause of extremes of heart rate (and potential ways to remedy them)

o Bradycardia

• Anesthetic overdose (lighten up)

• Opioid administration (give an anticholenergic)

• Alpha-2 agonist administration (reverse or no treatment)

• Hypothermia (rewarm)

• Hypoxia (oxygen therapy)

• 1st and 2nd degree A-V blockade (anticholenergics)

• High vagal tone (anticholenergics)

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