John R. Moyers

A cost/benefit analysis of randomized invasive monitoring for patients undergoing cardiac surgery

The aim of this study was to determine the effect of choice of invasive monitoring on cost, morbidity, and mortality in cardiac surgery. Two hundred and twenty-six adults undergoing elective cardiac surgery were initially assigned at random to receive either a central venous pressure monitoring catheter (group I), a conventional pulmonary artery (PA) catheter (group II), or a mixed venous oxygen saturation (S&OV0540;O2) measuring PA catheter (group III). If the attending anesthesiologist believed that the patient initially randomized to group I should have a PA catheter, that patient was then reassigned to receive either a conventional PA catheter (group IV) or S&OV0540;O2 measuring PA catheter (group V). The total costs were defined as the total amount billed to the patient for the catheter used; the professional cost of its insertion; and the determinations of cardiac output, arterial blood gas tensions, hemoglobin level, and hematocrit. Mean total monitoring and laboratory costs in Group I (

Comparison of a modified double-lumen endotracheal tube with a single-lumen tube with enclosed bronchial blocker

591 ± 67) were statistically significantly (P < 0.05) less than costs in Group II (

Dose-response relationship of isoflurane and halothane versus coronary perfusion pressures. Effects on flow redistribution in a collateralized chronic swine model.

856 ± 231). Further, mean monitoring and laboratory costs in Group II were statistically significantly (P < 0.05) less than those in Group III (

Correlates of Myocardial Oxygen Consumption when Afterload Changes during Halothane Anesthesia in Dogs

1128 ± 759). Patients in group IV incurred mean total costs of

Circulatory effects of isoflurane in patients with ischemic heart disease: a comparison with halothane.

986 ± 578, while those in group V had mean total costs of

Anesthesia for aortic valve replacement in a patient with acute intermittent porphyria

1126 ± 382 (NS). There were no significant differences between any of the groups with respect to length of stay in the intensive care unit, morbidity, or mortality. We conclude that use of a central venous pressure monitoring catheter was justified in low risk cardiac surgical patients, and that when PA catheters were used, additional costs were incurred. Additionally, monitoring of S&OV0540;O2 adds significant cost to that incurred with routine PA catheter use, but produces no discernible difference in patient outcome.

Importance of Anesthetic Equivalence

This study compared the modified BronchoCath[R] double-lumen endotracheal tube with the Univent[R] bronchial blocker to determine whether there were objective advantages of one over the other during anesthesia with one-lung ventilation (OLV). Forty patients having either thoracic or esophageal procedures were randomly assigned to one of two groups. Twenty patients received a left-side modified BronchoCath[R] double-lumen tube (DLT), and 20 received a Univent[R] tube with a bronchial blocker. The following were studied: 1) time required to position each tube until satisfactory, placement was achieved; 2) number of times that the fiberoptic bronchoscope was required; 3) frequency of malpositions after initial placement with fiberoptic bronchoscopy; 4) time required until lung collapse; 5) surgical exposure ranked by surgeons blinded to type of tube used; and 6) cost of tubes per case. No differences were found in: 1) time required to position each tube (DLT 6.2 +/- 3.1 versus Univent[R] 5.4 +/- 4.5 min [mean +/- SD]); 2) number of bronchoscopies per patient (DLT median 2, range 1-3 versus Univent[R] median 3, range 2-5); or 3) time to lung collapse (DLT 7.1 +/- 5.4 versus Univent[R] 12.3 +/- 10.5 min). The frequency of malposition was significantly lower for the DLT [5] compared to the Univent[R] [15] (P < 0.003). Blinded evaluations by surgeons indicated that 18/20 DLT provided excellent exposure compared to 15/20 for the Univent[R] group (P = not significant). We conclude that in spite of the greater frequency of malposition seen with the Univent[R], once position was corrected adequate surgical exposure was provided. In the Univent[R] group the incidence of malposition and cost involved were both sufficiently greater that we cannot find cost/efficacy justification for routine use of this device. (Anesth Analg 1996;83:1268-72)

Improvement of arterial oxygen saturation with selective lobar bronchial block during hemorrhage in a patient with previous contralateral lobectomy.

The authors studied the redistribution of myocardial blood flow in a collateral-dependent (CD) zone as a function of coronary perfusion pressure (CPP) during isoflurane and halothane anesthesia. A swine model with CD myocardium distal to a chronically occluded left anterior descending coronary artery was developed and studied. Sixteen piglets were allowed to grow for 8-10 weeks after banding of the left anterior descending coronary artery. They were randomly anesthetized with either isoflurane (n = 8) or halothane (n = 8) as the sole anesthetic, which was used to regulate specific CPP. The resultant regional myocardial blood flows were measured using radiolabeled microspheres. Four randomly allocated CPPs, of 30, 40, 45, and 55 mmHg, were studied in each animal. Four additional collateralized animals were anesthetized with alpha-chloralose, and the same CPPs were obtained using an intravenous adenosine infusion (1-5 microM kg-1) to validate this model. There was a proportional decrease in heart rate and blood pressure in both the isoflurane and and the halothane group with CPP. Cardiac output was significantly decreased in the halothane group at 30 mmHg when compared to 55-mmHg CPP, but it was maintained in the isoflurane group. Systemic vascular resistance was significantly lower in the isoflurane group at 30 and 40 mmHg when compared to 55-mmHg CPP. Both the isoflurane and the halothane group showed a proportional and significant decrease in endo-, mid-, and epicardial blood flows at 30-mmHg CPP when compared to baseline. In both CD and normal perfusion zones, isoflurane consistently sustained a higher endocardial blood flow than halothane (5.7-41.1%).(ABSTRACT TRUNCATED AT 250 WORDS)

The evolution of human resource needs in the USA

We have examined whether several clinically measurable correlates of myocardial oxygen consumption remain valid correlates when afterload changes during morphine or halothane plus morphine anesthesia. The correlates measured were heart rate, systolic blood pressure, left ventricular end diastolic pressure (LVEDP), and rate-pressure product (RPP). In six dogs we measured myocardial oxygen consumption (mVO2) and hemodynamic variables during morphine (4 mg/kg) and during morphine-halothane (1.5% end tidal concentration) anesthesia. We changed ventricular afterload by infusion of nitroprusside or phenylephrine and measured mVO2 as the product of left anterior descending coronary artery flow and arterial-coronary sinus oxygen content difference. RPP was the best correlate of mVO2 during both morphine-halothane (R = 0.84) and morphine anesthesia (R = 0.71). Systolic pressure and LVEDP also significantly correlated with mVO2 during both anesthetic states. The slope of the line relating RPP and mVO2 was significantly (p < 0.05) depressed during added halothane anesthesia. This slope depression (0.016 vs 0.021) is of little practical consequence within the physiologic range of RPP. Regression analysis showed that systolic pressure and heart rate alone account for the major part of changes in mVO2 during morphine-halothane anesthesia under the conditions of this experiment. After allowing for changes in LVEDP associated with systemic pressure, LVEDP still had significant effects on mVO2 during morphine anesthesia, but not during morphine-halothane anesthesia. We conclude that RPP is the best correlate of mVO2 under morphine-halothane anesthesia over a wide range of ventricular afterload states.

Invasive Monitoring of Cardiac Surgical Patients

The circulatory effects of isoflurane (I) were compared with those of halothane (H) in two groups of patients premedicated with morphine and scopolamine and scheduled for coronary artery bypass surgery. Both groups were similar with respect to age, weight, sex distribution, body surface area, left ventricular function, and preoperative dose of propranolol. While the patients were awake and breathing 100% oxygen, cardiac output and related hemodynamics were measured. The patients were then anesthetized by the same anesthesiologist with either isoflurane or halothane plus 50% N2O in O2. Ventilation was controlled to keep Paco2 within the normal range. Hemodynamic measurements were repeated 10 min after intubation and during surgery 10 min after sternotomy. Heart rate did not change significantly in either group. Arterial blood pressure fell equally during anesthesia and returned toward baseline values during surgical stimulation in both groups. Cardiac output decreased in both groups during anesthesia and surgery. Cardiac output decreased significantly (P < 0.05) more in the H group during surgery than in the H group. Systemic vascular resistance was significantly (P < 0.05) lower in the I group during anesthesia and surgery. The manner and degree of maximum increases in arterial pressure and heart rate after intubation and the onset of surgical stimulation were similar in both groups.