The use of pulsatile perfusion during aortic valve replacement in pregnancy.

Cardiac operations are occasionally required during pregnancy. Despite a low maternal mortality, fetal mortality remains high. Previous reports have suggested maintenance of high perfusion pressure and flow rate as protective measures to maintain fetal viability. Recent experimental data suggest pulsatile perfusion may help preserve placental hemodynamic function. The successful use of pulsatile bypass to replace the aortic valve in a 25-year-old female at 14 weeks gestation, with both maternal and fetal survival, is presented.

Patent foramen ovale and pulmonary embolism. An underestimated co-morbidity following cardiac surgery.

When pulmonary embolism occurs in the presence of a patent foramen ovale the sudden increase in the right heart pressure can open the defect and could cause right to left atrial shunting. This may further aggravate the already existing hypoxemia, and the direct communication between the venous and the arterial circulation increases the risk of paradoxical embolization. In this paper we present a case of postoperative pulmonary embolization in a patient with patent foramen ovale, and the effects of these co-existing conditions are reviewed. In the cardiac surgical literature such a complication has not yet been described.

Propofol versus midazolam for intensive care unit sedation after coronary artery bypass grafting.

OBJECTIVE: To compare the safety and effectiveness of propofol (2,6-diisopropylphenol) to midazolam for sedation of mechanically ventilated patients after coronary artery bypass grafting. DESIGN: Open, randomized, prospective trial. SETTING: Cardiothoracic intensive care unit (ICU), Cleveland Clinic Foundation. PATIENTS: Eighty-four patients with normal or moderately impaired left ventricular function who underwent elective coronary artery bypass graft surgery under high-dose opioid anesthesia. INTERVENTIONS: Patients were randomly selected to receive either propofol (mean loading dose 0.24 mg/kg; mean maintenance dose 0.76 mg/kg/hr) or midazolam (mean loading dose 0.012 mg/kg; mean maintenance dose 0.018 mg/kg/hr). Infusion rates were titrated to keep patients comfortable, drowsy, and responsive to verbal stimulation. Study duration, 8 to 12 hrs; infusions were started in the ICU when patients were awake and hemodynamically stable. MEASUREMENTS AND MAIN RESULTS: During therapy, both groups had lower mean arterial pressures and heart rates compared with baseline measurements; however, the propofol group had significantly lower heart rates than the midazolam group during the first 2 hrs of infusion. The propofol group also had significantly lower blood pressure measurements 5 and 10 mins after the initial dose, although there was no difference during infusion. Baseline cardiac output was measured before starting the infusion, and measurements were repeated during continuous infusion at 4, 8, and 12 hrs. Cardiac output values were similar. Propofol maintenance infusions ranged from 3 to 30 micrograms/kg/min and midazolam infusions ranged from 0.1 to 0.7 micrograms/kg/min. At these infusion rates. both groups had adequate sedation, based on nurse and patient evaluations; however, the propofol group used significantly lower total doses of sodium nitroprusside and supplemental opioids. CONCLUSIONS: Both propofol and midazolam provided safe and effective sedation of coronary artery bypass graft patients recovering from high-dose opioid anesthesia. The reduced need for both antihypertensive medication and opioids seen in the propofol group may be advantageous. However, the hypotension seen after the initial bolus dose of propofol may be a concern. No difference between the two drugs could be demonstrated in time to extubation or ICU discharge, although it is probable that time to extubation was governed more by residual operative opioids than the study agents.

Alpha-adrenergic agonist drugs, left ventricular function, and emergency from cardiopulmonary bypass.

The relationship between preoperative left ventricular (LV) dysfunction and the use of alpha-adrenoceptor agonists during weaning from cardiopulmonary bypass was studied in 102 patients undergoing coronary artery surgery. LV function was evaluated subjectively by examination of the 30 degree right anterior oblique left ventriculogram. Group 1 consisted of 75 patients with normal or mild impairment in LV function, whereas group 2 consisted of 27 patients with moderate-severe LV dysfunction. Cardiovascular parameters were measured at baseline, during hypothermic bypass with the aorta clamped, during normothermic bypass after unclamping, and 1 and 15 minutes after separation from bypass. Thirty-seven patients in group 1 (49%) and 11 patients in group 2 (39%) required some form of inotropic and/or vasopressor support during weaning from bypass. Group 2 required significantly higher cumulative doses of phenylephrine after bypass compared with group 1 (1.69 +/- 0.70 mg, n = 9, v 0.24 +/- 0.04 mg, n = 27, P less than 0.05). Similarly, the dose of norepinephrine infusion in group 2 was 3.3 times that in group 1 (10 +/- 6 micrograms/min, n = 2, v 3 +/- 0.6 micrograms/min, n = 2, P = NS). The higher doses of alpha-adrenoceptor agonists required in patients with moderate-severe LV dysfunction may be due to differences in alpha-adrenoceptor agonist affinity and/or receptor density.

Intravenous droperidol decreases nausea and vomiting after alfentanil anesthesia without increasing recovery time.

The frequency rate of nausea and vomiting after an alfentanil-based anesthetic is high, with reported frequencies of 38% to 68%. This study was undertaken to evaluate the efficacy of low-dose and moderate-dose droperidol in decreasing the frequency of postoperative nausea and vomiting and to evaluate whether droperidol has any effect on slowing recovery after a standard alfentanil-based anesthetic. Sixty normal adults who were scheduled to undergo short surgical procedures requiring general anesthesia were assigned randomly in a double-blind manner to one of three groups of 20: (1) control--normal saline; (2) droperidol 10 micrograms/kg; or (3) droperidol 20 micrograms/kg. A standard alfentanil-based anesthetic was used, and the study drug was given immediately after induction of anesthesia. In the post-anesthesia recovery room, all patients were evaluated according to the Aldrete score, noting the time to achieve a score of 10. Presence or absence and severity of nausea and vomiting were noted. To assess psychomotor recovery, a Trieger dot test was performed by every patient preoperatively, at the time of an Aldrete score of 10, and upon discharge from the recovery room. There was no statistical difference between the groups in age, sex, type of procedure, weight, total dose of alfentanil, or duration of anesthetic. The frequency of nausea and vomiting was significantly less (p less than 0.05) for the 20 micrograms/kg group (5%) than for the 10 micrograms/kg group (25%) or the control group (40%). A dose-response relationship was evident for the antiemetic effect of droperidol. An analog scale for severity of nausea and vomiting also demonstrated a dose response effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular, pulmonary, and renal effects of massively increased intra-abdominal pressure in critically ill patients.

Massive elevation of intra-abdominal pressure (IAP) causes cardiovascular, respiratory, and renal dysfunction. We managed eight patients with high IAP (mean 51 +/- 7 cm H2O), six of whom had hemodynamic measurements; a clinical syndrome, characterized by hemodynamic, respiratory, and renal dysfunction, then became apparent. We report a) a baseline cardiopulmonary profile and response to an acute vascular volume challenge in six patients and b) surgical decompression of the abdomen in four patients. The clinical impression of hypovolemia was confused by small to normal left ventricular end-diastolic volume (64 +/- 14 ml) and normal ejection fraction (55 +/- 6%) despite very high right and left atrial filling pressures. Complete ventilatory support was necessary to maintain oxygenation and ventilation; oliguria (urine output less than 10 ml/h) was present. Pericardial effusion was absent. After fluid challenge (10 ml/kg of colloid or crystalloid infused iv over 10 min), filling pressures, cardiac output, and stroke volume all increased significantly (p less than .025) while heart rate decreased. Surgical decompression of the abdomen improved oxygenation, ventilation, cardiac output, atrial filling pressures, and urine output within 15 min. The cardiovascular effects of massively elevated IAP compounded by the requisite supportive care may require surgical relief.