The World Federation of Societies of Anaesthesiologists: supporting education in the developing world.

The World Federation of Societies of Anaesthesiologists (WFSA) was formed in 1955 and is currently composed of 120 national societies. The aims of WFSA are to improve the standards of anaesthesia worldwide, with a particular emphasis in developing countries. This article details the structure of the WFSA, the various activities carried out by the different committees, and our achievements in education and training.

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

This study compared the modified BronchoCath double-lumen endotracheal tube with the Univent 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 double-lumen tube (DLT), and 20 received a Univent 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 5.4 +/- 4.5 min [mean +/- SD]); 2) number of bronchoscopies per patient (DLT median 2, range 1-3 versus Univent median 3, range 2-5); or 3) time to lung collapse (DLT 7.1 +/- 5.4 versus Univent 12.3 +/- 10.5 min). The frequency of malposition was significantly lower for the DLT (5) compared to the Univent (15) (P < 0.003). Blinded evaluations by surgeons indicated that 18/20 DLT provided excellent exposure compared to 15/20 for the Univent group (P = not significant). We conclude that in spite of the greater frequency of malposition seen with the Univent, once position was corrected adequate surgical exposure was provided. In the Univent 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.

Can atherosclerotic coronary arteries vasodilate? An intraoperative high-frequency epicardial echocardiographic study.

Our purpose was to evaluate the vasodilating responses of atherosclerotic coronary arteries using intraoperative high-frequency (12 MHz) epicardial echocardiography. We obtained continuous high-frequency epicardial echocardiographic recordings during surgery, and determined cross-sectional lumen area from 17 coronary arterial segments (12 patients). Nitroglycerin (100 to 400 micrograms/min) was administered intravenously to reduce mean (+/- SEM) arterial pressure 14 +/- 1.8 mm Hg. The cross-sectional arterial images were classified using 3 different parameters: arterial lumen area, percentage of the arterial wall circumference that was atherosclerotic (wall thickness > 0.7 mm), and presence of an eccentrically shaped arterial lumen (maximal/minimal luminal diameter > 1.5). Nine arterial segments had small (< 5.0 mm2) arterial lumens (1.7 +/- 0.40 mm2 [+/- SEM; range 0.6 to 3.9]). With nitroglycerin, the luminal area increased 0.8 +/- 0.28 mm2 (range 0 to 2.5), and 39 +/- 12.1% (range 0 to 117). The remaining 8 segments had larger (> 5.0 mm2) lumens (8.7 +/- 0.91 mm2 [range 5.0 to 11.9]). With nitroglycerin the luminal area increased 4.3 +/- 1.11 mm2 (range 1.4 to 11.4), and 51 +/- 10.2% (range 16 to 96). Seven arterial segments had eccentric lumens; mean maximal/minimal ratio was 1.8 +/- 0.08 (range 1.6 to 2.0). The area increased 39 +/- 7.3% (range 16 to 71) with nitroglycerin. In the 10 concentrically shaped lumens (maximal/minimal lumen diameters 1.3 +/- 0.04 [range 1.1 to 1.5]), nitroglycerin increased luminal area by 48 +/- 12.6% (range 0 to 117) (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of an interactive learning system with "sensorized" manikin head for airway management instruction.

An interactive, self-study learning system for airway management instruction that utilizes a "sensorized" manikin head (Actronics Inc., Pittsburgh, PA) was compared to didactic instruction from anesthesiologists during third-year medical student anesthesia rotations. Before students were allowed to participate in airway management on anesthetized patients, they were randomly separated into two groups. One group received instruction from the learning system, and the other group was given a lecture with guided practice on a standard tracheal intubating manikin. Differences between groups were then assessed using 22 separate variables as all students performed actual airway management on patients undergoing general anesthesia. Anesthesia faculty, residents, and nurse anesthetists, blinded to group, served as assessors. There were 48 and 49 students in the didactic instruction and learning system groups, respectively. Beginning experience level of students with respect to airway management was similar between groups before the anesthesia rotations. There were 185 and 188 evaluation forms completed to assess the didactic instruction and learning system groups, respectively. Demographic data regarding patients were recorded. Patients in the learning system group on whom students performed airway management were older, had a larger average body mass index, and their airways more frequently received higher Mallampati classifications (glottic structures more difficult to visualize). No difference in the quality of airway management efforts or in students' appraisal of their own performances was seen between groups. Neither group demonstrated more rapid development of psychomotor skills. Students were equally satisfied with both methods of instruction.(ABSTRACT TRUNCATED AT 250 WORDS)

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

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)

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 (SvO2) 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 SvO2 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 ($591 +/- 67) were statistically significantly (P less than 0.05) less than costs in Group II ($856 +/- 231). Further, mean monitoring and laboratory costs in Group II were statistically significantly (P less than 0.05) less than those in Group III ($1128 +/- 759). Patients in group IV incurred mean total costs of $986 +/- 578, while those in group V had mean total costs of $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.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of cardiopulmonary bypass and cold cardioplegia on coronary flow velocity and the reactive hyperemic response in patients and dogs.

In normal coronary arteries, reactive hyperemic responses to a 20-second occlusion, an index of coronary reserve, usually demonstrate a peak-to-resting flow velocity ratio of 4:1 or more. Most intraoperative studies that have assessed reactive hyperemic responses in bypassed vessels have reported peak-to-resting flow velocity ratios of 2:1 or less following a 20-second occlusion. These decreased reactive hyperemic responses could be due to coronary vasodilatation after cardiopulmonary bypass or to an inadequate physiological result of the surgical procedure. In 14 patients with angiographically normal coronary arteries, the peak-to-resting flow velocity ratio following a 20-second coronary occlusion decreased significantly (p less than 0.05) from 4.4 +/- 0.2 (mean +/- standard error) before bypass to 3.0 +/- 0.3 after bypass. In a similar dog model, the peak-to-resting flow velocity ratio decreased by 36 to 52% during the first hour following one hour of cardiopulmonary bypass and cardioplegia. During the same period, left ventricular perfusion increased 21 to 30%, mean arterial pressure and coronary vascular resistance decreased, and myocardial oxygen consumption was unchanged. In a second group of dogs studied for the effects of duration (200 to 240 minutes) of anesthesia and thoracotomy alone, peak-to-resting flow velocity ratio was significantly lower. These clinical and experimental studies suggest that major coronary vasodilatation occurs early following cardiopulmonary bypass and cold cardioplegia, and may contribute to the blunted coronary reactive hyperemic responses reported during this time. Consequently, an intraoperative peak-to-resting flow velocity ratio of 3:1 for bypassed coronary arteries may represent an excellent physiological result.

A survey of transfusion practices among anesthesiologists.

A survey of transfusion practices was conducted among anesthesiologists practicing in the United States to determine if significant variation exists and to identify those areas toward which research and educational efforts should be directed. Thirty-seven percent (389) of 1,043 active members of the American Society of Anesthesiologists who received the survey responded. The indications for transfusion as well as the types of components administered were found to vary considerably. Among the areas which need to be addressed are arbitrary preoperative hemoglobin requirements, indications for fresh frozen plasma administration, preoperative blood ordering and autologous transfusion.

Circulatory effects of atracurium in patients with cardiovascular disease.

Atracurium 0.4 mg kg-1, which was sufficient to produce neuromuscular blockade sufficient for intubation, was administered as divided bolus doses to 40 patients with severe cardiovascular disease. Little haemodynamic change occurred. A transient reduction in arterial pressure was noted in one patient. Atracurium was found to be safe and effective, and administration in small bolus doses separated by 30 s may reduce the likelihood of significant circulatory changes.

Segmental analysis of thallium 201 myocardial perfusion scintigraphy: its value in a community hospital.

In a community hospital, we correlated results of thallium 201 myocardial scintigraphy with coronary arteriographic data in 79 patients. Scintigraphy was 92% sensitive and 85% specific in detecting coronary artery disease. There were no false-negative scintigrams in patients with double or triple vessel disease. The most important factors determining sensitivity of the method in detecting individual coronary stenoses were (1) location of the stenosis in the coronary tree, (2) number of vessels involved, and (3) degree of obstruction. Higher prevalence of perfusion defects in areas of 90% to 99% stenosis as compared with 50% to 89% lesions was of borderline statistical significance (86% vs 59%; P = .06). Myocardial perfusion scintigraphy was unable to predict the number of significantly narrowed coronary vessels. Predictive value of a perfusion defect for a significant coronary stenosis was 87% for anterior, 88% for septal, 90% for lateral, 89% for posterior, and 78% for inferior segment. We conclude that segmental analysis of myocardial scintigrams may be of value in a community hospital.

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

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 less than 0.05) more in the H group during surgery than in the I group. Systemic vascular resistance was significantly (P less than 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.

Vasomotor dynamics associated with cardiac operations. II. Effect of cardiopulmonary bypass on venous tone.

The effect of cardiopulmonary bypass on venous tone was evaluated in 19 patients undergoing coronary artery bypass graft operations. The use of cardiopulmonary bypass with reduction of mean arterial pressure, nonpulsatile blood flow, and emptying of the heart maximally stimulates the sympathoadrenal system and would be expected to cause intense venous constriction. Venous capacitance, however, was reduced by the general effects of the operation, including anesthesia and surgical trauma, while cardiopulmonary bypass was a minor factor in the venous constriction response.

Halothane and morphine-nitrous oxide anesthesia in patients undergoing coronary artery bypass operation. Patterns of intraoperative ischemia.

To examine whether the hemodynamic responses to halothane or morphine-nitrous oxide anesthesia produce different patterns of myocardial ischemia in patients undergoing myocardial revascularization, we studied 26 patients anesthetized with nitrous oxide (50%) and either halothane (0.2% to 1.0% end-tidal concentration) or morphine (2 mg/kg, given intravenously). We measured systemic and coronary hemodynamics and took blood samples to measure blood gases, oxygen content, and lactate and norepinephrine concentrations. Systemic blood pressure, rate-pressure produce, systemic vascular resistance, cardiac output, and stroke work were elevated following sternotomy in patients anesthetized with morphine, whereas halothane obtunded these hemodynamic responses to surgical stress. Intraoperative myocardial ischemia occurred in both patient groups. Ten of 14 patients receiving halothane and eight of 12 receiving morphine had at least one episode of either ST-segment depression or myocardial lactate production. The difference between these groups was not statistically significant. Only patients anesthetized with morphine had a significantly elevated rate-pressure product when ischemia occurred. In this selected series of patients subjected to myocardial revascularization, two sustained a myocardial infarction and four died in the postoperative period. The incidence of these and other indices of postoperative morbidity was not related to choice of primary anesthetic and did not differ between the patients who sustained ischemia and those who did not.

Changes in mixed venous and coronary sinus P50 secondary to anesthesia and cardiac disease.

Changes in oxyhemoglobin dissociation compensate partially for decreased O2 transport caused by high altitude, anemia, and cardiac disease. This investigation determined whether similar changes occurred in patients undergoing myocardial revascularization and the possible significance of such changes. In 15 patients scheduled for coronary vein bypass surgery the following were inserted: a #7 French catheter into the coronary sinus or great cardiac vein, a pulmonary arterial catheter (Swan-Ganz), and a radial arterial catheter. Patients were anesthetized with either halothane-N2O 50% or morphine (2 mg/kg IV) with N2O 50%. Hemodynamic status was measured and blood samples were taken from the catheters in the preoperative period and after endotracheal intubation, sternotomy, bypass, and chest closure. Blood samples were analyzed for pH, blood gas tensions, and O2 saturation. Values for P50 for mixed venous and coronary sinus blood were calculated from O2 tension and saturation. Patients were divided into two groups on the basis of peroperative mixed venous P50 values: group I had normal P50 levels of 26.1 +/- 2.0 torr (mean +/- SD); group II had elevated values for mixed venous blood P50 of 32.5 +/- 1.6 (mean +/- SD). Unlike group I, group II had depressed ventricular function and higher P50 values for coronary sinus blood than for mixed venous blood. Induction of anesthesia increased P50 values in group I but not in group II and removed the significant differences between group I and group II mixed venous P50 values. In group II patients, cardiopulmonary bypass lowered the elevated P50 of coronary sinus blood so that it equaled P50 for mixed venous blood. It is concluded that induction of anesthesia may elevate P50 in patients who have normal preoperative P50 values. The already elevated P50 values of patients with ventricular dysfunction did not change. Cardiopulmonary bypass decreased coronary sinus P50 in group II patients, and this change might be deleterious if the original elevation represents a compensatory response to a reduction in O2 transport.