The influence of hyperoxic ventilation during sodium nitroprusside-induced hypotension on skeletal muscle tissue oxygen tension

Anesthesiology. 2002 May;96(5):1103-8. doi: 10.1097/00000542-200205000-00012.

Abstract

Background: Increasing inspired oxygen concentrations might provide a simple and effective intervention to increase oxygen tension in tissues during controlled hypotension. To test this hypothesis, the influence of hyperoxic ventilation (100% O2) on skeletal muscle oxygen partial pressure (Ptio2) in patients receiving sodium nitroprusside-induced controlled hypotension was studied.

Methods: Forty-two patients undergoing radical prostatectomy were prospectively studied and randomly divided into three groups as follows: (1) Controlled hypotension induced by sodium nitroprusside (mean arterial blood pressure, 50 mmHg) and hyperoxic ventilation (CH-100%; n = 14); (2) controlled hypotension and ventilation with 50% O2 in nitrous oxide (CH-50%; n = 14); and (3) standard normotensive anesthesia with 50% O2 in nitrous oxide (control; n = 14). Ptio2 values were measured continuously in all patients using implantable polarographic microprobes. Arterial blood gases and lactate concentrations were analyzed in 30-min intervals.

Results: Surgical blood loss and transfusion requirements were significantly reduced in both groups receiving hypotensive anesthesia. During surgery, arterial partial pressure of oxy-gen and arterial oxygen content were significantly higher in patients of the CH-100% group. Baseline values of Ptio2 were comparable between the groups (CH-50%: 25.0 +/- 0.7 mmHg; CH-100%: 25.2 +/- 0.2 mmHg; control: 24.5 +/- 0.2 mmHg). After a transient increase in Ptio2 in the CH-100% group during normotension, Ptio2 values returned to baseline and remained unchanged in the control group. Ptio2 decreased significantly during the hypotensive period in the CH-50% group. The lowest mean Ptio2 values were 15.0 +/- 4.1 mmHg in the CH-50% group, 24.2 +/- 4.9 mmHg in the CH-100% group, and 23.5 +/- 3.8 mmHg in the control group. There were no significant changes in lactate plasma concentrations in any group throughout the study period.

Conclusions: Hyperoxic ventilation improved skeletal muscle tissue oxygenation during sodium nitroprusside-induced hypotension. This improved local tissue oxygenation seems to be most likely due to an increase in convective oxygen transport and the attenuation of hyperoxemia-induced arteriolar vasoconstriction by sodium nitroprusside.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Retracted Publication

MeSH terms

  • Aged
  • Anesthesia
  • Anesthetics, Inhalation
  • Antihypertensive Agents / pharmacology*
  • Blood Gas Analysis
  • Desflurane
  • Humans
  • Hypotension, Controlled / adverse effects*
  • Isoflurane / analogs & derivatives
  • Male
  • Middle Aged
  • Muscle, Skeletal / metabolism*
  • Nitroprusside / pharmacology*
  • Oxygen / blood
  • Oxygen Consumption / drug effects
  • Oxygen Consumption / physiology*
  • Oxygen Inhalation Therapy*
  • Polarography
  • Prostatectomy

Substances

  • Anesthetics, Inhalation
  • Antihypertensive Agents
  • Nitroprusside
  • Desflurane
  • Isoflurane
  • Oxygen