A Pregnant Patient With a Large Anterior Mediastinal Mass for Thymectomy Requiring One-Lung Anesthesia.

Anesthetic management for anterior mediastinal mass resection is often challenging. The main concern being that the tumor might, on reduction in muscle tone, cause circulatory and/or airway collapse. In the setting of pregnancy, the expected physiologic changes (eg, increased oxygen demand, decreased functional residual capacity, and aortocaval compression) may further increase the risks. The objective of this report is to present a challenging case of a pregnant woman undergoing an anterior mediastinal mass resection with the additional rare requirement for one-lung anesthesia, and to describe the perioperative considerations and the plan executed to ensure a successful outcome. A 30-year-old pregnant (23 weeks) patient with a large anterior mediastinal mass and evidence of significant cardiovascular and tracheobronchial compression presented for thymectomy requiring one-lung ventilation. Anesthesia consisted of preoperative preparation, thoughtful selection of vascular access sites, preservation of spontaneous ventilation until sternotomy was accomplished, use of bronchial blocker and readily reversible pharmacologic agents, availability of backup airway and oxygenation plans, standby high-frequency ventilation, and anticipation of postoperative respiratory difficulties. Surgical considerations included the possibility of extracorporeal membrane oxygenation and the need for lifting the thymoma to relieve the compression of the mediastinum. A methodical and multidisciplinary plan is described to mitigate the risk of cardiorespiratory collapse in the setting of anterior mediastinal mass resection. Backup measures in case of catastrophe, as well as careful consideration of the physiologic changes of pregnancy, must be taken into account.

Gastroesophageal reflux and tracheobronchial contamination after cardiac surgery: should a nasogastric tube be routine?

Nasogastric (NG) tubes are routinely used in patients undergoing cardiac surgery. This randomized study was designed to assess gastroesophageal reflux (GER) without a NG tube (control) compared with a NG tube managed either by gravity drainage (gravity) or continuous low-grade suction (suction). Antimony pH probes were placed in the lower esophagus and trachea after induction of anesthesia in 51 patients, and pH was recorded every 5 s until the time of tracheal extubation. GER was defined as reversible decrease in esophageal pH to less than 4.0. No significant difference was found between groups in age, weight, gender, duration of postoperative ventilation, morphine use, or antiemetic use. All indicators of GER were seen more frequently in the gravity group compared with the two other groups (P < 0.001). One episode of sudden decrease in tracheal pH was observed in a patient in the gravity group, indicating tracheal aspiration, which was associated with delayed extubation and postoperative pneumonia. The absence of a NG tube is not associated with reflux, probably since the gastroesophageal sphincter remains competent. NG tubes are not routinely necessary for cardiac surgery in patients without risk factors for GER, and increase reflux risk if managed without low-grade suction.

Renal function and proteinuria after cardiopulmonary bypass: the effects of temperature and mannitol.

We studied three groups of patients without previous renal impairment, undergoing elective coronary artery bypass surgery. Group H (n = 7) underwent open heart surgery using moderate hypothermia (28 degrees C); Groups N and M (n = 8, each) were managed at normothermia. The extracorporeal circuit was primed with Hartmann's solution 2.5 L with the addition of mannitol 0.5 g/kg in Group M. Serum concentrations of sodium and creatinine, and the urinary concentrations of microalbumin and N-acetyl-beta-D-glucosaminidase (NAG) were measured in each patient at six different time intervals: T0, 6 h prior to surgery; T1, between sternotomy and 45 min into cardiopulmonary bypass (CPB); T2, in the interval from 45 min into, to prior to weaning off CPB; T3, from coming off CPB to skin closure; T4, in the first 6 h in the intensive care unit; and T5, at 6 days postoperatively. Creatinine clearance (CCR) and fractional sodium excretion (FENA) were calculated at each time point. Urine output during CPB at Interval T2 was significantly higher in Group H compared to Group N (P = 0.03) but not Group M. We found no significant differences in CCR, FENA, microalbuminuria, and urinary NAG among the three groups at any time. However, there were overall significant changes in measured variables over time compared to baseline. We conclude that CPB is associated with a significant alteration in renal function as shown by increased FENA, microalbuminuria, and urinary NAG. The use of hypothermic or normothermic CPB and the use of prophylactic mannitol did not produce any significant modification of these changes.

Variation in the arterial to end-tidal PCO2 difference during one-lung thoracic anaesthesia.

We have measured the arterial to end-tidal PCO2 difference (PaCO2-PE'CO2) in 22 patients undergoing pulmonary resection in the lateral thoracotomy position during two-lung ventilation (TLV) and after transition to one-lung ventilation (OLV). With OLV for each patient, the practice of correcting the estimate by an initial measurement of (PaCO2-PE'CO2) was evaluated by subtracting the initial (PaCO2-PE'CO2) from subsequent values measured at 10-min intervals. Net (uncorrected) and corrected differences during OLV were analysed using ANOVA. (PaCO2-PE'CO2) values during TLV and OLV were similar: mean (SD) 1.3 (0.6) kPa and 1.2 (0.7) kPa, respectively (ns). Mean (PaCO2-PE'CO2) varied in the range 0.2-2.5 kPa, while maximum (PaCO2-PE'CO2) was 0.3-2.8 kPa. The mean (SD) of 133 pairs of measurements with OLV was 1.1 (0.7) kPa. Even after correction, mean (PaCO2-PE'CO2) varied in the range -0.7 to 0.8 kPa; individual extreme values were from -1.3 to 1.7 kPa. Variation between patients was found to be greater than variation within patients for both net and corrected differences (F ratio = 37.0 and 10.9, respectively), although calculating a corrected difference did reduce variation between patients from a mean square value of 2.44 to 0.61. The wide variation in (PaCO2-PE'CO2) suggests that the accuracy of estimation of PaCO2 by monitoring PE'CO2, although improved by the use of a corrected difference, remains questionable during OLV.

Comparison of the haemodynamic effects of dobutamine with enoximone after open heart surgery in small children.

We have studied 28 children (mean age 13.6 months) undergoing elective cardiac surgery involving a myocardial ischaemic time greater than 60 min. Thirteen received phenoxybenzamine 1 mg kg-1 before cardiopulmonary bypass (CPB) and dobutamine 10 micrograms kg-1 min-1 before discontinuation of CPB; 15 received enoximone 0.5 mg kg-1 followed by an infusion of 10 micrograms kg-1 min-1 before discontinuation of CPB. Haemodynamic variables were measured at intervals for 6 h after CPB. Two patients in each group required additional inotropic support with adrenaline. Heart rates, right and left atrial pressures, mean pulmonary artery pressures and systemic and pulmonary vascular resistance indices were similar in the two groups. Mean arterial pressure was significantly greater in those receiving dobutamine (61.3 (SD 7.6) mm Hg) compared with enoximone (56.2 (5.3) mm Hg) (P < 0.05). Differences in cardiac index (thermodilution) (dobutamine group 2.92 (0.62) litre min-1 m-2; enoximone group 2.55 (0.55) litre min-1 m-2) and left ventricular stroke work index (dobutamine group 13.1 (4.7) g m beat-1 m-2; enoximone group 10.4 (2.7) g m beat-1 m-2) were not statistically significant. Enoximone may be used successfully in these patients to assist discontinuation of CPB and maintain an acceptable haemodynamic state in the early postoperative period but, when used alone, conferred no advantage compared with the combination of dobutamine and phenoxybenzamine.

Effect of surveillance on the number of hysterectomies in the province of Saskatchewan.

In 1972 the College of Physicians and Surgeons of Saskatchewan appointed a committee to study hysterectomies because the Saskatchewan Department of Health had data showing that the annual number of hysterectomies carried out in the province had increased by 72.1 per cent between 1964 and 1971, whereas the number of women over 15 years of age had increased by 7.6 per cent. The committee compiled a list of indications for hysterectomy. Any hysterectomy carried out for one of these reasons was classified as justified, and the remainder as unjustified. Five hospitals were reviewed in 1970 and a further two in 1973. In 1974, all seven hospitals were reviewed again. In these hospitals, the average proportion of unjustified hysterectomies had dropped from 23.7 per cent at the time of the first review to 7.8 per cent in 1974. The total number of hysterectomies in the province dropped by 32.8 per cent between 1970 and 1974.