It has been generally accepted that carboxyhemoglobin levels between 10-20% produce mild headaches, dizziness and/or nausea. Experimental double blind exposures of 18 healthy, nonsmoking young men at rest to 7,000-24,000 ppm CO, designed to elevate COHb to 15-20% in 3-5 minutes, were followed by exposure to 232 ppm CO designed to maintain COHb level for a total of 130 minutes. Resulting COHb values were 16-23%. These COHb values did not produce significantly more symptoms (as reported in an open-ended questioning) than reported in the control group (n = 23). Subjects were especially queried about headache, dizziness and nausea. The symptoms which were previously reported in clinical studies of CO poisoning may have resulted from CO exposure in combination with (a) exposure to other substances, (b) stress due to the event that precipitated medical attention or (c) higher COHb levels before the first blood sample was taken.

Adolescent↗

PubMedDate not supplied

Improved oxygenation during thoractomy with selective PEEP to the dependent lung.

In 22 patients during thoracotomy in the lateral position, the effects of selective positive end-expiratory pressure (PEEP) to the dependent lung while simultaneously ventilating the non-dependent lung at zero end-expiratory pressure (ZEEP) on (1) inspired O2 concentration required to maintain adequate Pao2 during thoractomy and 2) alveolar-arterial oxygen difference (AaO2D) while breathing 100 percent O2 at the end of thoractomy were examined and compared to ventilation of both lungs at ZEEP, Selective PEEP to the dependent lung resulted in adequate PaO2 with a lower inspired O2 concentration (44 +/- SD 6% versus 70 +/- SD 21%), and a smaller AsO2D while breathing 100 percent O2 189 +/- SD 31 versus 342 +/- SD 69 torr) at the end of thoracotomy.

Blood Gas Analysis↗

PubMedDate not supplied

Pulse oximetry: evaluation of accuracy during outpatient general anesthesia for oral surgery.

Pulse oximetry has been shown to be accurate under steady state conditions. In this study, the accuracy of four pulse oximeters are evaluated and compared during outpatient general anesthesia for third molar extractions. The oximeters evaluated are the Nellcor N-100, the Ohmeda 3700, the Novametrix model 500, and the Bird 4400 portable pulse oximeter.Ultralight general anesthesia for oral surgery presents a unique challenge for respiratory monitoring in that patients are often not intubated and commonly experience periods of hyper- and hypoventilation. Airway obstruction, apnea, and laryngospasm may occur easily and patients often vocalize and move during surgery. Because hypoxemia is the primary cause of morbidity and mortality during anesthesia, an accurate, continuous, and noninvasive monitor of oxygenation is critical to risk management.Twenty ASA class I and II patients underwent outpatient general anesthesia for third molar removal using nitrous oxide-oxygen, midazolam, fentanyl, and methohexital. Arterial blood samples were obtained at five-minute intervals during anesthesia, as well as any time a desaturation of >5% occurred, for measurement of arterial SaO(2) with an IL282 CO-Oximeter. These values were compared with simultaneously recorded saturations observed for each pulse oximeter. A total of 122 arterial samples were obtained over a range of PaO(2) from 52-323 mm Hg and observed saturations of 70-100%.The Bird 4400 portable pulse oximeter proved to be the most accurate and reliably predicted arterial saturation under these conditions (y = 1.03x - 2.8, r = 0.85). The Novametrix model 500 pulse oximeter also demonstrated a high degree of accuracy by linear regression analysis, but displayed the lowest correlation coefficient (spread of data points) overall (y = 0.97x + 2.8, r = 0.80.) The Nellcor N-100 pulse oximeter also proved to be highly accurate. (y = 1.05x - 4.1, r = 0.84.) In contrast, regression analysis of the observed saturations obtained with the Ohmeda 3700 pulse oximeter revealed that this unit significantly underestimated arterial saturation (y = 1.20x - 19.6, r = 0.83.)This study demonstrates that despite the rigorous conditions imposed by outpatient general anesthesia for oral surgery, three of the pulse oximeters tested were linearly accurate in predicting arterial oxyhemoglobin saturation over the range of 70-100%. The Ohmeda 3700 was found to significantly underestimate arterial saturation.

Ambulatory Care↗

PubMedDate not supplied

Respiratory and cardiovascular functions in scoliosis.

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Adolescent↗

PubMedDate not supplied

Regulation of the tidal volume and ventilatory responses to CO2 in normal man and in scoliosis.

The variation of the ventilatory response to CO2 and its pattern among normals and in the presence of pulmonary disease is wide. In normal subjects the relationship between the slopes of the ventilatory (delta V/delta PCO2), tidal volume (delta VT/delta PCO2) and the frequency (delta f/delta PCO2) responses and body size, metabolic rate, resting ventilation and pattern, lung volumes or mechanical properties of the respiratory system have only been demonstrated in a few studies. In idiopathic scoliosis there is a positive correlation between the delta V/delta PCO2 and delta VT/delta PCO2 and body size, resting ventilation and tidal volume, lung volumes and compliance of the respiratory system. Although there were significant correlations between the delta V/delta PCO2 and the delta VT/delta PCO2 and th delta f/delta PCO2 the correlation between the delta VT/delta PCO2 and delta f/delta PCO2 was not significant. Correlations between the delta f/delta PCO2 and lung volumes, compliance or body size were also not significant. Therefore variation in the frequency response to CO2 contribute to the variation between individuals of the delta V/delta PCO2 and this variation is unrelated to respiratory mechanics or body size. We conclude that in human studies any examination of possible relationships between ventilatory response to CO2 and body size, lung volumes and mechanics should examine separately the tidal volume and frequency response to CO2. We postulate that the tidal volume response is the most appropriate variable to normalize for lung volumes, e.g., vital capacity (delta VT/VC/delta/ PCO2).

Adult↗

PubMedDate not supplied

Vendor questionnaire to evaluate product quality, service, and support.

A questionnaire was developed to obtain verifiable data on the quality of a manufacturer's product, availability and quality of service, qualifications of service personnel, availability of spare parts, availability of inservice training programs for users and clinical engineering staff, history and future support of product, and technical requirements for preventive maintenance and repair. The questionnaire was constructed on the premise that product quality, service, and support throughout the life of the instrument are of equal importance to the function and price in purchase decisions. They play an important role in determining the true cost of patient monitoring equipment and contribute to the quality, safety, and efficiency of patient care.

Commerce↗