Ferret, rabbit, and rodent anesthesia.

Ferrets, rabbits, and rodents are increasingly being presented to veterinarians for evaluation and treatment. The owners of these animals expect high-level medical and surgical care. Consequently, veterinarians are more often required to provide intensive anesthetic management of these animals. The variability of anesthetic agents used and patient responses are addressed. The consequences of size for anesthetic management are discussed. Successful small mammal anesthesia requires following general anesthetic principles, awareness of limitations, and maintenance of high standards of care.

Inadvertent severe hypercarbia associated with anesthesia machine malfunction in one cat and two dogs.

Severe acute hypercarbia occurred in a cat and 2 dogs as a result of anesthesia machine malfunction. In each case, the anesthesia machine had been checked by the anesthesia technician and clinician, and no problems were found. After it was noticed that the same machine had been used on each animal, further investigation revealed an expiration valve that was functional with large breaths or positive pressure ventilation but was not functional with small breaths with low peak inspiratory flow. Rebreathing of expired carbon dioxide occurred, and the patients subsequently became severely hypercarbic. Recovery from anesthesia was prolonged in 2 animals, and cardiac and respiratory arrest occurred in the third. Hypercarbia from rebreathing can be detected through the use of blood gas analysis or end-tidal carbon monoxide monitoring.

One-lung versus two-lung ventilation in the closed-chest anesthetized dog: a comparison of cardiopulmonary parameters.

OBJECTIVE: To evaluate cardiopulmonary effects of one-lung ventilation (OLV) versus two-lung ventilation (TLV) in closed-chest anesthetized dogs. STUDY DESIGN: Controlled, randomized experiment. ANIMALS: Fourteen, 2- to 7-year-old adult dogs, weighing 23 +/- 6 kg. METHODS: The dogs were anesthetized with acepromazine, morphine, thiopental, and halothane in oxygen, ventilated, and paralyzed with vecuronium. Tidal volume was 10 mL/kg. Respiratory rate was set to maintain end-tidal CO2 (ETCO2) at 40 +/- 2 mm Hg before instrumentation then not changed. The left bronchus of 7 dogs was obstructed with a Univent bronchial blocker (Fuji Systems Corp, Tokyo, Japan). Blood gas analysis and hemodynamic measurements were taken at predetermined intervals for 1 hour in the TLV group and at baseline and following bronchial obstruction in the OLV group. RESULTS: Shunt fraction was not significantly different between groups, but in OLV shunt increased from baseline at 5 minutes. Arterial oxygen (PaO2) decreased after baseline in OLV compared with TLV. Arterial carbon dioxide (PaCO2) increased with OLV and decreased with TLV. In OLV, systemic vascular resistance was variable and decreased compared with TLV. Cardiac index increased over time in both groups but was not affected by treatment. Heart rate, mean arterial pressure, and diastolic arterial pressure increased with OLV compared with TLV but did not change over time. CONCLUSION: This study shows that OLV statistically decreases oxygen tension and transiently increases shunt fraction, but with 100% O2 it appears to be a feasible procedure with minimal cardiopulmonary side effects in healthy dogs. CLINICAL RELEVANCE: OLV is a feasible procedure in anesthetized dogs to better facilitate thoracic procedures such as bronchopleural fistula repair and thoracoscopy.

Intravenous regional anesthesia (Bier block) in a dog.

Intravenous regional anesthesia was used in an adult dog as part of a balanced approach to general anesthesia for amputation of the 4th digit of its right hind limb. It allowed the concentration of isoflurane to be reduced to 0.5%.

The effect of opioid and acepromazine premedication on the anesthetic induction dose of propofol in cats.

The median effective dosage (ED50) for induction of anesthesia with propofol was determined by using the up-and-down method in 31 unpremedicated cats, in 30 cats premedicated with butorphanol, 0.4 mg/kg body weight (BW), and acepromazine, 0.1 mg/kg BW, intramuscularly, and in 30 cats premedicated with morphine, 0.2 mg/kg BW, and acepromazine, 0.1 mg/kg BW, intramuscularly. The dose required for a satisfactory anesthetic induction in 50% of unpremedicated cats (ED50) was 7.22 mg/kg BW and of premedicated cats was 5.00 mg/kg BW. The reduction in dose was statistically significant in both premedicated groups compared with no premedication. There was no significant difference in ED50 between premedication regimes. Cyanosis was the most common adverse effect observed in all groups following anesthetic induction with propofol.

A comparison of indirect blood pressure monitoring techniques in the anesthetized cat.

OBJECTIVE: To determine the accuracy of three indirect blood pressure monitoring techniques (oscillometric technique [OS], Doppler [DOP], and optical plethysmography [OP] [blood pressure determined with a pulse oximeter waveform]) when compared with direct arterial pressure measurement in cats. STUDY DESIGN: Prospective study. ANIMAL POPULATION: Eight healthy (five female, three male), domestic short-hair cats weighing 3.5 +/- 0.8 kg METHODS: Cats were anesthetized with isoflurane. The inspired concentration of isoflurane was adjusted to produce mild hypotension (80 to 100 mm Hg direct systolic), moderate hypotension (60 to 80 mm Hg direct systolic), and severe hypotension (< 60 mm Hg direct systolic). Indirect pressure measurements were obtained from the thoracic limb and compared with concurrent direct measurement using regression analysis and a modification of Bland and Altman's technique. RESULTS: All three techniques underestimated systolic pressure. OS produced the best prediction of systolic pressure with a bias +/- precision of -15.9 +/- 8.1 mm Hg. DOP and OP were relatively inaccurate with a bias +/- precision of -25 +/- 7.4 mm Hg and -25 +/- 7.5 mm Hg. All three techniques correlated well with direct pressure with r values of 0.81, 0.88, and 0.88 for OS, DOP, and OP. DOP and OP provided an accurate prediction of direct mean arterial pressure with a bias +/- precision of -0.8 +/- 6 mm Hg and 0.6 +/- 5.5 mm Hg. Correlation was good between DOP and mean arterial pressure with r = 0.89. Correlation was also good between OP and mean arterial pressure with r = 0.90. CONCLUSIONS: OS provided the most accurate prediction of direct systolic pressure. DOP and OP provided a good prediction of mean arterial pressure in the cat. CLINICAL RELEVANCE: All three of these techniques are useful for detecting trends. Direct monitoring of blood pressure should be considered if accurate blood pressure measurement is required.