Hemodynamic effects of morphine during and early after cardiac operations.

Hemodynamics and blood gases were measured before and 15 minutes after small (10 mg/70 kg) doses of intravenously administered morphine in two groups of patients having open heart surgery. In one group, the study was undertaken after median sternotomy but before perfusion. The other group had been in the intensive care unit for approximately 1 hour. No changes were found in either group in cardiac index, atrial pressures, arterial pressure, or blood gas variables. However, mean systemic vascular resistance decreased from 41.5 to 35.4 after morphine was given postoperatively. Hence, hemodynamically, morphine is a safe drug if given in small doses for pain relief and sedation early after open heart surgery.