Hypoxia following etorphine administration in goats (Capra hircus) results more from pulmonary hypertension than from hypoventilation

BMC Veterinary Research

Andrea Fuller¹  Duncan Mitchell¹  Robyn Sheila Hetem¹  Leith Carl Rodney Meyer¹ 

[1] Brain Function Research Group, School of Physiology, University of the Witwatersrand, 7 York Road, Parktown 2193, South Africa

关键词: Oxygen diffusion;    Respiratory depression;    Opioid;    Hypoxia;   

Others  :  1131429
DOI  :  10.1186/s12917-015-0337-5

 received in 2014-09-25, accepted in 2015-01-22,  发布年份 2015

【 摘 要 】

Background

Etorphine, a potent opioid agonist, causes pulmonary hypertension and respiratory depression. Whether etorphine-induced pulmonary hypertension negatively influences pulmonary gas exchange and exacerbates the effects of ventilator depression and the resultant hypoxemia is unknown. To determine if these effects occurred we instrumented twelve goats with peripheral and pulmonary arterial catheters to measure systemic and pulmonary pressures before and after etorphine administration. Concurrent cardiopulmonary and arterial blood gas variables were also measured.

Results

Etorphine induced hypoventilation (55% reduction to 7.6 ± 2.7 L.min⁻¹, F_(11,44) = 15.2 P < 0.0001), hypoxia (<45 mmHg, F_(11,44) = 8.6 P < 0.0001), hypercapnia (>40 mmHg, F_(11,44) = 5.6 P < 0.0001) and pulmonary hypertension (mean 23 ± 6 mmHg, F_(11,44) = 8.2 P < 0.0001). Within 6 min of etorphine administration hypoxia was twice (F_(11,22) = 3.0 P < 0.05) as poor than that expected from etorphine-induced hypoventilation alone. This disparity appeared to result from a decrease in the movement of oxygen (gas exchange) across the alveoli membrane, as revealed by an increase in the P(A-a)O₂ gradient (F_(11,44) = 7.9 P < 0.0001). The P(A-a)O₂ gradient was not correlated with global changes in the ventilation perfusion ratio (P = 0.28) but was correlated positively with the mean pulmonary artery pressure (P = 0.017, r² = 0.97), indicating that pulmonary pressure played a significant role in altering pulmonary gas exchange.

Conclusion

Attempts to alleviate etorphine-induced hypoxia therefore should focus not only on reversing the opioid-induced respiratory depression, but also on improving gas exchange by preventing etorphine-induced pulmonary hypertension.

【 授权许可】

   
2015 Meyer et al.; licensee BioMed Central.

【 图 表 】

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