Addition of nitrous oxide to fentanyl anesthesia does not induce myocardial ischemia in patients with ischemic heart disease.

Although nitrous oxide is commonly administered to patients with ischemic heart disease, recent reports suggest that it may induce myocardial ischemia in these patients. The authors compared the effects of nitrous oxide on segmental left ventricular (LV) function and the ST segment of the electrocardiogram with the effects of an equal concentration of nitrogen (crossover design) before the start of surgery in 18 patients who required coronary-artery bypass grafting. The patients studied did not have valvular or LV dysfunction. Anesthesia was induced and maintained with intravenous fentanyl. After endotracheal intubation and 20 min of ventilation with 100% oxygen, either 60% nitrous oxide or 60% nitrogen (randomly assigned) was added to the inspired gas mixture of each patient for 10 min. This was followed by 10 min of 100% oxygen, and then 10 min of 60% nitrous oxide or 60% nitrogen, whichever had not been administered previously. Patients were monitored for myocardial ischemia using a standard 12-lead electrocardiogram and trans-esophageal two-dimensional echocardiography. Surgery did not begin until the study was concluded. No patient experienced an ST segment change greater than 1 mm during the study, and none developed a new segmental wall motion abnormality during inhalation of either nitrous oxide or nitrogen. The authors conclude that nitrous oxide does not induce myocardial ischemia when used as an adjunct to fentanyl anesthesia in patients who have severe coronary-artery disease accompanied by well-preserved valvular and LV function.

Schistosoma haematobium: effect of non-schistosomicidal drugs (tetracycline and sulphadimidine) on schoolchildren.

Pupils attending four secondary boarding schools in Mwanza Municipality, Tanzania, were examined parasitologically for Schistosoma haematobium. Prevalence of infection was highest in the age group 17 to 18 years in both sexes whereas the intensity was highest in the age group 15 to 16 years in girls and 17 to 18 in boys. Absence on grounds of sickness among the pupils studied was not related to the infection and the over-all academic performance was not clearly related to S. haematobium infection in either. Two drugs (tetracycline-HCL and sulphadimidine) commonly used for treatment of many bacterial infections in Tanzania were used. Administration of these drugs to schistosomiasis patients showed that both significantly lowered egg excretion and the degree depended on the dosage. Neither drugs affected the hatching of miracidia. It is speculated that the administration of both drugs might contribute to a higher accumulation of the eggs in the tissues. This effect could lead to more pathogenic effects as well as introducing an element of error in the studies on drug trials and chemotherapy. Treatment using metrifonate (Bilarcil) resulted in cure rates of 76% for girls and 93% for boys.

Color-coded Doppler imaging of systolic flow patterns in hypertrophic cardiomyopathy.

We studied 11 patients with hypertrophic cardiomyopathy by color Doppler echocardiography (Group I: 6 patients with outflow obstruction, and Group II: 5 patients without outflow obstruction) to assess systolic structure and function as observed by cross-sectional echocardiography in relation to the flow dynamics. The structure and function included systolic anterior motion of mitral valve (SAM), midsystolic aortic valve closure (AoC), systolic cavity obliteration and the presence and timing of mitral incompetence. Their occurrence and timing was related to presence of aortic systolic flow and presence of turbulence. While all patients in Group I had SAM and turbulence, none of the patients in Group II had SAM nor turbulence. Early mitral incompetence appearing before SAM and turbulence, occurred in all patients of Group I and in none of Group II. Midsystolic aortic valve closure was only present in Group I and blood flow was unilaterally directed so that only 60% of aortic cross-sectional area showed blood flow. We conclude that mitral incompetence in hypertrophic cardiomyopathy in early systole is common when outflow gradient is present and is independent of mitral incompetence of mid- and late systole. During SAM, turbulence in the subaortic area and mid and late mitral incompetence occurred simultaneously. The midsystolic aortic valve closure was related to the unilaterally directed blood flow through the aortic cross-sectional area.