A comparison of the effects of carbon dioxide and medical air for abdominal insufflation on respiratory parameters in xylazine-sedated sheep undergoing laparoscopic artificial insemination.

AIMS

To determine if abdominal insufflation with medical air will improve oxygenation and ventilation parameters when compared to insufflation with CO in xylazine-sedated sheep undergoing laparoscopic artificial insemination (AI).

METHODS

Forty-seven sheep underwent oestrus synchronisation and were fasted for 24 hours prior to laparoscopic AI. Each animal was randomised to receive either CO or medical air for abdominal insufflation. An auricular arterial catheter was placed and utilised for serial blood sampling. Respiratory rates (RR) and arterial blood samples were collected at baseline, after xylazine (0.1 mg/kg I/V) sedation, 2 minutes after Trendelenburg positioning, 5 minutes after abdominal insufflation, and 10 minutes after being returned to a standing position. Blood samples were collected in heparinised syringes, stored on ice, and analysed for arterial pH, partial pressure of arterial O (PaO), and CO (PaCO). The number of ewes conceiving to AI was also determined.

RESULTS

Repeated measures ANOVA demonstrated temporal effects on RR, PaO, PaCO and arterial pH during the laparoscopic AI procedure (p<0.001), but no difference between insufflation groups (p>0.01). No sheep experienced hypercapnia (PaCO>50 mmHg) or acidaemia (pH<7.35). Hypoxaemia (PaO<70 mmHg) was diagnosed during the procedure in 14/22 (64%) ewes in the CO group compared with 8/23 (35%) ewes in the medical air group (p=0.053). Overall, 15/20 (75%) ewes in the CO group conceived to AI compared with 16/22 (72.7%) in the medical air group (p=0.867).

CONCLUSIONS AND CLINICAL RELEVANCE

There were no statistical or clinical differences in RR, PaO, PaCO, pH, or conception to AI when comparing the effects of CO and medical air as abdominal insufflation gases. None of the sheep experienced hypercapnia or acidaemic, yet 42% (19/45) of sheep developed clinical hypoxaemia, with a higher percentage of ewes in the CO group developing hypoxaemia than in the medical air group. Based on the overall analysis, medical air could be utilised as a comparable alternative for abdominal insufflation during laparoscopic AI procedures.