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| ANESTHETIC MONITORING: YOUR QUESTIONS ANSWERED
Table 2. Cardiorespiratory & Physiologic Parameters in the Anesthetized Dog & Cat Variable
Dog Circulation
Heart rate (beats per min) Systolic blood pressure (mm Hg) Diastolic blood pressure (mm Hg) Mean arterial blood pressure
Ventilation
Respiratory rate (breaths per min) Tidal volume (mL/kg) Arterial blood pH
PaCO2 (mm Hg) Bicarbonate (mmol/L) End-tidal CO2
Oxygenation Other
SpO2 (%) PaO2 (mm Hg)
Body temperature (°F) Hematocrit (%) Total protein (mg/dL) Blood glucose (mg/dL) Blood lactate (mmol/L) Urine output (mL/kg/H)
60–120 90–140 60–90 70–90
8–16 10–15
7.35–7.45 35–45 22–26 35–45
≥ 95 ≥ 100
98–101 34–59 5–8.3
90–150 < 2 1–2
Cat
120–160 90–140 60–90 70–90
12–24 10–15
7.35–7.45 35–45 22–26 35–45
≥ 95 ≥ 100
98–101 28–47
5.9–8.4 90–150 < 2 1–2
CO2 = carbon dioxide; PaCO2 = partial pressure of carbon dioxide in the arterial blood; PaO2 = partial pressure of oxygen in the arterial blood; SpO2 = saturation level of oxygen in hemoglobin
What are the Target Physiologic Values for the Anesthetized Dog & Cat? *hÞÃiolo}iVÊ>n`ÊV>À`ioÀiëiÀ>ÌoÀÞÊÛ>Ài>LliÃÊinÊ>niÃÌhi- tized dogs and cats are listed in Table 2.
What are Important Components of Anesthetic Monitoring? UÊPre-anesthetic Evaluation: The monitoring pro- cess starts prior to premedication. It begins by obtaining a complete history of the patient, fol- lowed by a thorough physical examination, includ- ing blood analysis and indicated diagnostics. The patient is given an ASA (American Society of Anesthesiologists) classification based on assessment of its anesthetic risks (Table 3). Deficits in homeostasis, such as dehydra-
tion, anemia, or any other significant abnor- mality (eg, low total protein, electrolyte imbalance, endocrine dysfunction, bleed- ing disorders) should be stabilized prior to any anesthetic procedure. A recent study has shown that mortality rates are higher in small animals with higher ASA status (ASA III–V) regardless of anesthetic agents used.2
UÊMonitoring All Anesthetic Phases: Once pre-anesthetic evaluation has been com- pleted and the patient is approved for anes-
thesia, monitoring continues through: » Ê*Àimi`iV>Ìion » Induction » Maintenance » Recovery.
26 Today's Veterinary Practice January/February 2012
Monitoring also applies to patients that have been prescribed take-home pain medication; this is accomplished through follow-up phone calls with the owner.
UÊSedated Patients: Sedated patients should also be monitored. Both the American College of Veterinary Anesthesiologists3
Hospital Association4
(ACVA) and the American Animal (AAHA) have monitoring
guidelines, which emphasize that a sedated patient should receive the same quality of monitoring care as a patient under general anesthesia. To review these guidelines, see Links to Anesthesia Guidelines, page 23.
Table 3. American Society of Anesthesiologists Physical Status Classification System
ASA Classification Animal Health Description
ASA I ASA II ASA III ASA IV
ASA V ASA-E
UÊNormal, healthy
UÊMild to moderate systemic disease UÊSevere systemic disease, but still active
UÊSevere systemic disease and incapacitated
UÊMoribund, terminally ill UÊEmergency