Role of adenosine in the diagnosis and treatment of postoperative supraventricular tachyarrhythmias.

Adenosine (Adenocard) has a potent but very transient negative dromotropic effect on atrioventricular (A-V) nodal conduction. By slowing A-V nodal conduction, adenosine may interrupt a re-entry pathway causing paroxysmal supraventricular tachycardia or facilitate the diagnosis of other supraventricular tachycardia (SVT) by exposing the underlying atrial activity. We report 15 postoperative cases in which adenosine was used to clarify the diagnosis of postoperative SVT, and allowed the appropriate postoperative care.

A comparison of esmolol and labetalol for the treatment of perioperative hypertension in geriatric ambulatory surgical patients.

This is an open randomized study comparing the efficacy and safety of i.v. esmolol and labetalol in the treatment of perioperative hypertension in ambulatory surgery. Twenty-two elderly patients undergoing cataract surgery under local anaesthesia were studied. The main inclusion criteria were development of systolic blood pressure greater than 200 mmHg or diastolic greater than 100 mmHg. Esmolol was given as a bolus 500 micrograms.kg-1 i.v. followed by a maintenance infusion (150-300 micrograms.kg-1.min-1). Labetalol was given as a bolus of 5 mg i.v. followed by 5 mg increments as needed up to a maximum of 1 mg.kg-1. Esmolol and labetalol both produced reductions in systolic and diastolic blood pressure (P less than 0.05) within ten minutes of administration which lasted for at least two hours. Reduction of blood pressure by esmolol was accompanied by a decrease in HR (P less than 0.05). Two patients developed extreme bradycardia (HR less than 50 beats.min-1) and esmolol had to be discontinued. Labetalol, in contrast, induced only a moderate decrease in HR. None of the patients treated with labetalol experienced any prolonged side effects such as orthostatic hypotension. In conclusion, esmolol may produce considerable bradycardia in elderly patients when hypertension is not accompanied by tachycardia. Labetalol was easier to administer in the ambulatory setting and one-tenth the cost of esmolol.

Evaluation of oxygen saturation monitoring by pulse oximetry in neonates in the delivery system.

The pulse oximeter was evaluated for use in neonates in the delivery room. One hundred neonates, delivered vaginally or by Caesarean section with general or epidural anaesthesia, were studied. After delivery, pulse oximetry probes were placed simultaneously on the ulnar side of the right hand and on the right Achilles tendon to determine whether there was a difference in arterial oxygenation (SpO2). Measurements of SpO2 were taken at 1, 5, 10 min, and 24 hr after delivery. At one and five minutes, SpO2 recorded from the right hand was higher than that recorded from the lower extremities (71.9% +/- 6.5% vs 63.4% +/- 4.3% and 83.3% +/- 4.2% vs 76% +/- 4.1%, mean +/- SD, respectively). At ten minutes these differences diminished, and had almost completely disappeared after 24 hr. These results can be explained by the presence of R-L shunting at the ductus arteriosus level, producing reduced SaO2 in the lower extremities. Oxygen saturation did not differ between neonates delivered vaginally or by Caesarean section, regardless of the presence or type of anaesthesia. We concluded that neonates remain relatively desaturated in the immediate postpartum period and that the SpO2 obtained from the right hand is a better index of neonatal oxygenation than that obtained from the heel.

A comparison of the Puritan-Bennett 7200a ventilator's flow-by mode to the T-piece mode prior to extubation in postsurgical patients.

UNLABELLED: We compared flow-by ventilation (FB) via the Puritan-Bennett 7200a ventilator with T-piece ventilation (TP) during weaning from mechanical ventilation (MV). METHODS: We placed 22 consecutive postsurgical patients being weaned from MV on FB at base flows of 10 L/min and 20 L/min and then on TP. Blood pressure, pulse rate, respiratory rate, blood gases, tidal volume, and peak inspiratory flow were measured after at least 20 min in each mode. Statistical analysis of clinical status used a three-level, one-way analysis of variance with technique as a within-subjects factor. Setup costs of the three ventilatory modes were evaluated using relative value units for labor plus actual costs of added equipment and supplies. RESULTS: Although there was a statistically significant difference in PaCO2 among the ventilatory modes, this was not clinically important. No other differences were found. Each FB mode cost $2.55 to set up, whereas TP cost $11.90. CONCLUSIONS: FB and TP were clinically equivalent. However, the alarm and monitoring capabilities during FB are useful and may be worth the one-time cost ($1,000) of adding the optional flow-by software to the 7200a ventilator.

The effects of intravenous cimetidine and metoclopramide on gastric pH and volume in outpatients.

STUDY OBJECTIVE: To evaluate and compare the preinduction effects of intravenously (IV) administered cimetidine alone and combined with metoclopramide on gastric contents and postoperative nausea and vomiting in outpatients undergoing elective surgery. DESIGN: Patients were allocated randomly to 4 groups with 20 patients in each group. SETTING: Ambulatory surgery at a university-affiliated city hospital. PATIENTS: Eighty patients undergoing elective gynecologic or orthopedic procedures were studied. INTERVENTIONS: Outpatients in Group 1 and inpatients in Group 2 served as controls. Outpatients in Group 3 received 300 mg of cimetidine, and outpatients in Group 4 received 300 mg of cimetidine and 10 mg of metoclopramide. All drugs were administered IV as an infusion over a 15-minute period, 30 to 45 minutes prior to induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: After induction of general anesthesia and endotracheal intubation, stomach contents were retrieved and volume and pH measured. Group 1 outpatients had a large residual gastric volume of 29.2 +/- 15.9 ml, with a very low pH of 2.32 +/- 1.23 and 15% frequency of postoperative vomiting. These patients are at high risk of developing significant pneumonitis in the event of the aspiration of gastric contents. The combination of cimetidine and metoclopramide in Group 4 provided the optimal, or safest, condition--i.e., high gastric pH [6.15 +/- 0.71 (p less than 0.005)] and low gastric volume [11.6 +/- 7.37 ml (p less than 0.001)], with no postoperative vomiting. CONCLUSIONS: The combination of cimetidine and metoclopramide given to ambulatory patients during the preinductive phase may prevent severe pulmonary consequences should aspiration occur and is more effective in this regard than cimetidine alone.

Clinical management of malignant hyperpyrexia.

Experience with eight cases of malignant hyperpyrexia are presented. The different types are described and illustrated by clinical cases. Early recognition of this condition is the cornerstone in the successful management of the complication. Early diagnosis and methods of treatment are described.