The effects of pneumoperitoneum and patient position on hemodynamics during laparoscopic cholecystectomy.

BACKGROUND: The purpose of this study was to prospectively examine the combined effects of pneumoperitoneum and the reverse Trendelenberg position on cardiac hemodynamics during laparoscopic cholecystectomy. METHODS: Thirty-nine patients undergoing laparoscopic cholecystectomy as performed by a single surgeon were enrolled in the study. Hemodynamic data were collected continuously using a transthoracic bioimpedance monitor. All patients were subjected to insufflation pressures of 15 mmHg. Data were examined using mixed analysis of variance (ANOVA). RESULTS: Cardiac index fell 11% with induction of anesthesia (p < 0.05), with stroke volume decreasing 7.2% (p < 0.05). Insufflation caused significant decreases in stroke volume (SV) left ventricular end diastolic volume (LVEDV) but not cardiac index (CI). Placing the patients in the reverse Trendelenberg position caused no significant changes in these parameters. There were no significant differences between ASA (American Society of Anesthesiologists) classes I and II patients when compared to ASA III patients. CONCLUSIONS: Patients undergoing laparoscopic cholecystectomy experience significant hemodynamic depression. The effect of general anesthesia is the most profound. Insufflation of the abdomen caused more mild hemodynamic effects in our study. The addition of a reverse Trendelenberg position did not alter the patient's hemodynamic status.

Intramedullary pressure and pulmonary function during total knee arthroplasty.

Twenty-eight patients who underwent unilateral total knee arthroplasty and 20 patients who underwent simultaneous bilateral total knee arthroplasties participated in this study and were randomized to have either a fluted or round 10-mm diameter femoral intramedullary alignment rod used during surgery. The intramedullary rods were cannulated and connected with pressure tubing to a monitor which provided measurements of pressure at the tip of each rod. Arterial blood gas measurements on room air were obtained before and on the morning after surgery. An arterial line was placed and an arterial blood gas measurement was obtained at the time of skin incision and again after tourniquet release. Pulmonary shunt was calculated from the arterial blood gas measurements. Intramedullary pressure during rod insertion was significantly higher for the groups of patients having the round compared with the fluted rod. The change in pulmonary shunt during surgery was lowest for the patients in the unilateral group having the fluted rod and highest for the patients in the bilateral group having the round rod. A fluted rather than a round intramedullary alignment rod should be used to minimize intramedullary pressure and pulmonary shunting during unilateral and bilateral total knee arthroplasties.

Pulmonary function during and after total hip replacement. Findings in patients who have insertion of a femoral component with and without cement.

Eleven patients who had a femoral component inserted with cement and twenty-three who had a femoral component inserted without cement were studied prospectively for changes in the pulmonary shunt associated with total hip replacement. The levels of oxygen in the arterial blood and the platelet counts were measured preoperatively and each morning for three days after the arthroplasty. Levels of oxygen in the arterial blood were determined intraoperatively, once before and once after the femoral component was inserted. Intraoperative shunt values increased 28 per cent when a femoral component was inserted with cement (p < 0.05), but they did not change when cement was not used. The average postoperative shunt values were higher than the average preoperative shunt values for both groups of patients, but only the values on the second postoperative day after a procedure with cement were significantly higher (p < 0.05). The ability of the patient to tolerate an increase in pulmonary shunt should be assessed when the femoral component is to be cemented during total hip replacement.

Tetanus: a review.

Tetanus is caused by the organism Clostridium tetani, which produces tetanospasmin, a neurotoxin responsible for the clinical manifestations of muscle rigidity and reflex spasms. The majority of cases follow an anaerobic wound infection associated with trauma. Incubation period is usually 3 days to 3 weeks. 75% of patients present with trismus. Reflex spasms are seen in 70% of patients and characterize the severity of the disease. Treatment involves removal of the offending organism, neutralization of free neurotoxin, controlling rigidity and reflex spasm, and minimizing complications. Diazepam may be used alone in mild cases. Severe cases require the addition of nondepolarizing neuromuscular blocking agents and mechanical ventilation. Respiratory complications occur early and require aggressive airway management. A serious, late complication is the syndrome of sympathetic nervous system overactivity that is treated with alpha and beta blockade. High mortality rates seen in the United States may be due to delays in diagnosis and lack of familiarity with treatment. The disease is preventable with adequate immunization.

Mannitol dose requirements in brain-injured patients.

There is little information as to the optimal use of mannitol. To determine the dose-response relationship, the osmotic gradient required, and the time course of intracranial pressure (ICP) reduction produced by mannitol, eight patients with acute head injury were studied in whom ICP was monitored with a ventriculostomy and found to be elevated. Ventilation was controlled to a pCO2 of 25 +/- 3 mm Hg and all were paralyzed with Pavulon. None had received barbiturates. Before mannitol administration the intracranial volume-pressure response was determined. Mannitol was administered as a bolus of 0.25 gm/kg, 0.5 gm/kg, and in six patients, 1 gm/kg, separated by at least 8 hours. In all patients the ICP reduction with 0.25 gm/kg (41.3 +/- 10.2 mm Hg leads to 16.4 +/- 5.6, p less than 0.01) was equivalent to that achieved with the larger doses. Serum osmolality rises of 10 mOsm or more were associated with a reduction in ICP. Much smaller doses than those previously recommended were effective in reducing the ICP acutely, although at 5 hours there was a trend toward persistent reduction when the larger dose is used. This trend was small and indicates that smaller and more frequent doses are as effective in reducing the ICP while avoiding the risk of osmotic disequilibrium and severe dehydration.

Anaesthesia and Huntington's chorea. A report of two cases.

Two patients with Huntington's chorea were anaesthetized successfully with a technique including thiopentone, nitrous oxide and either a narcotic analgesic or halothane; pancuronium was employed for myoneural blockade.

Oxygen availability during hypothermic cardiopulmonary bypass.

Oxygen availability during cardiopulmonary bypass was assessed in 22 patients under hypothermic and relatively normothermic conditions. The patients were divided into two groups, 17 of whom received ACD blood and 5, CPD blood. The mean P50 for all patients fell from a preoperative value of 25.9 +/- 2.4 (SD) to 15.6 +/- 2.1 during hypothermia confirming a leftward shift of the oxyhemoglobin dissociation curve. Oxygen uptake, calculated from a-v oxygen content differences (avDO2) and flow, was significantly lower during hypothermic bypass (65 +/- 27 ml/min) than during rewarming (121 +/- 41 ml/min). The increase in oxygen affinity during hypothermia was influenced also by changes in acid base and 2,3-DPG concentrations, the changes being similar in both the ACD and CPD groups of patients. During rewarming, however, oxygen availability was increased in the CPD group presumably from significantly increased 2,3-DPG concentrations. A "functional" value of hemoglobin, based upon the effects of the shift of the oxyhemoglobin dissociation curve and, therefore, reflecting the true capacity of hemoglobin to unload oxygen at the tissue level, was calculated. During the hypothermic phase of bypass, this functional hemoglobin was only 4.2 g/100 ml blood, suggesting that, in spite of reduced metabolic demands, oxygenation reserves are minimal.

An autoclavable ventilation failure alarm.

A small ventilation failure alarm which can be used with all types of lung ventilator is described. The entire patient circuit can be removed and autoclaved easily. Activation of the unit is by a removable key, a mains failure warning is provided, and alarm may be muted during aspiration of secretions from the tracheobronchial tree.