Measurement of Carboxyhemoglobin and Methemoglobin by Pulse Oximetry: A Human Volunteer Study

Background: A new eight-wavelength pulse oximeter is designed to measure methemoglobin and carboxyhemoglobin, in addition to the usual measurements of hemoglobin oxygen saturation and pulse rate. This study examines this device's ability to measure dyshemoglobins in human volunteers in whom controlled levels of methemoglobin and carboxyhemoglobin are induced.

Methods: Ten volunteers breathed 500 ppm carbon monoxide until their carboxyhemoglobin levels reached 15%, and 10 different volunteers received intravenous sodium nitrite, 300 mg, to induce methemoglobin. All were instrumented with arterial cannulas and six Masimo Rad-57 (Masimo Inc., Irvine, CA) pulse oximeter sensors. Arterial blood was analyzed by three laboratory CO-oximeters, and the resulting carboxyhemoglobin and methemoglobin measurements were compared with the corresponding pulse oximeter readings.

Results: The Rad-57 measured carboxyhemoglobin with an uncertainty of +/-2% within the range of 0-15%, and it measured methemoglobin with an uncertainty of 0.5% within the range of 0-12%.     

Treatment of the depressed and dysmorphophobic acne patient

Sixteen patients with minimal facial acne but with symptoms of dysmorphophobia related to their acne were treated with isotretinoin, 0.5 mg/kg/day, (n = 5); 1 mg/kg/day (n = 11) for 16 weeks. All 16 had previously received long-term antibiotic therapy with no 'perceived' improvement in their acne. Formal psychiatric assessment was not possible through lack of cooperation. Fourteen of 16 patients derived benefit from isotretinoin therapy in that all 14 were subsequently satisfied with the cosmetic results achieved. However, the incidence of relapse was greater than that for a control group, 14 requiring additional therapy in the form of antibiotics or further isotretinoin (seven patients) within 20 months of completing the original course. Patients with acne and dysmorphophobia represent an important group of patients who benefit from treatment with isotretinoin; if possible this should be in conjunction with psychotherapy.     

Echocardiographic detection of left circumflex coronary artery to left superior vena cava fistula by use of Doppler color flow mapping

We report the two-dimensional and Doppler color flow mapping echocardiographic findings in a neonate with left circumflex coronary arteriovenous fistula to a left superior vena cava. Doppler color flow mapping, in concert with detailed imaging, was essential to identify this rare fistula and to prepare for therapeutic intervention at initial cardiac catheterization.     

Health care heats up as potential presidential campaign issue

Health care professionals and election analysts agree that health care will be a bigger issue in the 1992 election than it was in 1988. Among the reasons: Some prominent members of Congress are active in health care issues, media coverage of health insurance problems is growing, and several major health care reform bills have been introduced in Congress.     

The Angelchik anti-reflux prosthesis and postoperative dysphagia

Dysphagia was studied in 29 patients after implantation of an Angelchik prosthesis for persistent reflux oesophagitis. The incidence of postoperative dysphagia occurred after three months (61%), six months (45%), and one year or more (41%). Severe dysphagia necessitated removal of the prosthesis in five patients (17%). The reoperative findings with regard to a possible explanation of dysphagia are discussed, and comparison is made with reports in literature. Implantation of the Angelchik prosthesis seems only indicated for the treatment of intractable reflux oesophagitis in patients where other operative modalities failed and who are at high risk for operation. The Nissen fundoplication remains the operation of choice.     

Specific effects of nitroprusside on myocardial O2 balance following coronary ligation in the dog heart

The effect of gradual infusion of nitroprusside was studied in healthy and in ischemic hearts. In two areas of the left ventricular surface (ischemic and non-ischemic) local coronary blood flow was measured by a thermistor technique. Isometric contractile tension was recorded with strain gauge arches, and nicotinamide-adenine-dinucleotide (NADH) redox state was measured simultaneously in both regions using a two-channel fluorometer. Aortic blood pressure was also recorded. It was found that at an infusion rate of 1.0 microgram/kg/min, nitroprusside increased regional coronary blood supply in the healthy heart as well as in the ischemic and nonischemic areas of left anterior descending artery (LAD)-ligated hearts. Flow elevation was similar in all regions (37.0 +/- 6.1, 42.5 +/- 13.5 and 45.36 +/- 14.8%, respectively). At higher doses, a decrease of 6-10% in blood pressure had a detrimental effect on the coronary flow to the ischemic region without reducing flow to the nonischemic region. The NADH redox level was not significantly improved by nitroprusside in spite of elevated coronary blood supply to all regions examined. Moreover, higher doses of nitroprusside resulted in a significant elevation in NADH levels that could be correlated to the decrease in blood pressure. It is concluded that the effect of nitroprusside on coronary blood supply and myocardial O2 balance may be strongly dependent on the magnitude of its effect on blood pressure.