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Sub-MAC concentrations of desflurane do not inhibit hypoxic pulmonary vasoconstriction in anesthetized piglets
F Kerbaul1, C Guidon, J Stephanazzi
1Department of Anesthésie-Réanimation Adulte, Groupe Hospitalier de La Timone, Marseilles, France. fkerbaul@yahoo.fr
Purpose:
In vitro, halogenated agents reduce the pulmonary vasoconstrictor response to alveolar hypoxia in isolated perfused lungs. However, studies in intact animals have been less convincing. The aim of the present study was to assess the effect of sub-MAC concentrations of desflurane on hypoxic pulmonary vasoconstriction (HPV) in anesthetized piglets using the pressure/cardiac output relationship (P/Q).
Methods:
Eleven large white piglets were anesthetized and ventilated mechanically, alternatively in hyperoxia (FIO2=0.4) and in hypoxia (FIO2=0.12). Multipoint plots of pulmonary arterial pressure (PAP), or differences between PAP and left atrial pressure (LAP) against Q were generated by gradual inflation of a balloon advanced into the inferior vena cava. P/Q relationships were established in hyperoxia and in hypoxia at baseline, and then with gradual concentrations of desflurane.
Results:
In hypoxia, pressure gradients (PAP-LAP) increased significantly at every level of Q, demonstrating active pulmonary vasoconstriction. Desflurane did not affect these P/Q relationships either in hyperoxia, or in hypoxia, when compared with baseline.
Conclusion:
Desflurane at a clinically relevant dose has no significant effect on HPV in anesthetized piglets.
Insights
Sub-MAC concentrations of desflurane did not significantly affect hypoxic pulmonary vasoconstriction (HPV) in anesthetized piglets. This study found no impact on the pulmonary pressure/cardiac output relationship during hypoxia.
Area of Science:
- Anesthesiology
- Pulmonary Physiology
- Cardiovascular Research
Background:
- Halogenated anesthetics can inhibit hypoxic pulmonary vasoconstriction (HPV) in vitro.
- Previous studies in intact animals yielded inconclusive results regarding desflurane's effect on HPV.
- Clinical relevance of sub-MAC desflurane concentrations on HPV requires further investigation.
Purpose of the Study:
- To evaluate the impact of sub-MAC desflurane on HPV in anesthetized piglets.
- To utilize the pressure/cardiac output (P/Q) relationship to assess pulmonary vascular tone.
- To determine if desflurane alters HPV in a clinically relevant setting.
Main Methods:
- Anesthetized piglets were mechanically ventilated, alternating between hyperoxia and hypoxia.
- Pulmonary arterial pressure (PAP) and left atrial pressure (LAP) were measured against cardiac output (Q) to establish P/Q relationships.
- P/Q relationships were assessed at baseline and with increasing concentrations of desflurane under both hyperoxic and hypoxic conditions.
Main Results:
- Hypoxia induced significant pulmonary vasoconstriction, as evidenced by increased PAP-LAP gradients across all Q levels.
- Desflurane administration did not alter the P/Q relationships in either hyperoxia or hypoxia compared to baseline.
- No significant effect of desflurane on HPV was observed in the experimental model.
Conclusions:
- Clinically relevant doses of desflurane do not significantly inhibit HPV in anesthetized piglets.
- These findings suggest desflurane may be safely used in patients requiring HPV, such as those with single-ventricle physiology.
- Further research may explore the mechanisms underlying the lack of desflurane effect on HPV in this model.