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Biomedical subjects

R M Peters

Publications and source records attributed to R M Peters.

At least 109 records · Page 6Linked to original sources
PubMed1977

Mechanics of ventilation with positive end-expiratory pressure.

The effect of graded increments in positive end-expiratory pressure (PEEP) on arterial oxygen partial pressure (PaO2) and shunt fraction (Qs/QT), oxygen delivery, and respiratory mechanics and work required to ventilate 8 critically ill patients is reported. The work required to ventilate the patients increases markedly with the application and progressive increase in the level of PEEP. However, improvement in lung mechanics lowers the net work of ventilating the lungs. At 20 cm H2O PEEP, the mean value for the work of ventilation in this group of patients is twice the mean value without PEEP. The increase in work of ventilation with PEEP is critical in the use of PEEP when patients are breathing spontaneously with or without intermittent mandatory ventilation.

Adult↗
PubMed1977

A nomogram for planning respiratory therapy.

A nomogram is presented which aids in monitoring and selecting therapy in the treatment of the patient with hypoxemia. It facilitates accurate bedside determination of total shunt fraction and estimation of the arterial oxygen tension (PaO2) attainable at inspired oxygen concentrations of 21 percent to 100 percent. The nomogram permits rapid consideration of changes in hemoglobin concentration, arteriovenous oxygen content difference, and shunt fraction on the PaO2. The uses of the nomogram in several therapeutic contexts are discussed.

Carbon Dioxide↗
PubMed1977

Interpretation of alveolar-arterial oxygen tension difference.

In this study, an assessment is given of errors resulting from the use of the alveolar-arterial oxygen difference determined on both room air and 100% oxygen in estimating changes in total shunt fraction of 41 patients hospitalized with long bone fractures. In 113 studies, changes in alveolar-arterial oxygen difference in 29 patients were in the opposite direction to changes in shunt fraction. Based upon these studies, changes of less than 45 millimeters in the arterial oxygen tension determined with a patient breathing 100% oxygen are not reliable indicators of direction of change in shunt fraction. In 126 studies, the shunt fraction determined from arterial and mixed venous oxygen contents in 71 patients was greater when determined on 100% oxygen than when determined on room air, a possible indication of the induction of alveolar or small airway collapse. The errors in estimation of shunt fraction due to assuming a value for arteriovenous oxygen content difference become larger as total shunt fraction increases; in particular, use of the alveolar-arterial oxygen difference as a guide to serial changes in pulmonary dysfunction can be particularly misleading when the alveolar-arterial oxygen tension difference is so large that the arterial hemoglobin is less than fully saturated on 100% oxygen. Use of mixed venous samples was found necessary, in these instances, to avoid large errors in estimation of total shunt fraction.

Adult↗
PubMed1977

Multiorgan scans for staging lung cancer. Correlation with clinical evaluation.

One hundred consecutive patients with findings suggestive of resectable bronchogenic carcinoma were studied prospectively to determine if routine liver, brain, and bone scans (multiorgan scans) detected metastases which were not suggested by a history, physical examination, and serum chemistries. Multiorgan scans were compared with clinical evaluations in 52 patients found to have operable bronchogenic carcinoma. There was a discordance between scans and clinical evaluations in 25/153 scans (16 per cent). Two of the 22 negative scans in patients with abnormal clinical findings were false negative. Sixteen of the 17 positive scans in patients with normal clinical findings were false positive. One of the 131 scans done in patients with no evidence of metastases on clinical evaluation was true positive. These data indicate that the routine use of multiorgan scans in the initial staging of potentially resectable bronchogenic carcinoma is not justified.

Bone Neoplasms↗
PubMed1976

The effects of carbon dioxide on pulmonary mechanics in hyperventilating, normal volunteers.

Transpulmonary pressure, air flow, and end-tidal carbon dioxide levels were measured in normal human volunteers during hypocapnic, eucapnic, and hypercapnic hyperventilation. Respiratory rate and tidal volumes were well matched at a minute ventilation of 52 L. on three inspired gas mixtures: 21 per cent oxygen and 79 per cent nitrogen; 5 per cent carbon dioxide, 21 per cent oxygen and 74 per cent nitrogen; and 12 per cent carbon dioxide, 21 per cent oxygen and 67 per cent nitrogen. Respiratory rate, tidal volume, lung compliance, resistance, and resistive work per liter were calculated with a digital computer. In 13 experiments in 7 normal volunteers, no net bronchoconstriction or bronchodilatation was observed when eucapnic hyperventilation was compared to hypocapnic or hypercapnic hyperventilation. During hyperventilation of this degree, a change in bronchomotor tone owing to alteration in arterial or alveolar PCO2 either does not occur or else is masked by other reflexes or mechanical factors acting on the bronchi.

Adult↗
PubMed1976

Epidural anesthesia following thoracotomy in patients with chronic obstructive airway disease.

Epidural analgesia for control of postoperative thoracotomy pain in patients with carcinoma of the lung and chronic obstructive airway disease is described. The rationale and procedure for its use are presented. Epidural analgesia used in 8 patients requiring pulmonary resection who had chronic obstructive airway disease resulted in an improved postoperative course and avoided use of narcotics or a respirator in 7 of the 8 patients.

Aged↗
PubMed1975

Hemodynamic alterations with positive end-expiratory pressure: the contribution of the pulmonary vasculature.

The hemodynamic responses to positive end-expiratory pressure (PEEP) ventilation have been evaluated. A rise in pulmonary capillary wedge pressure which follows the use of PEEP may not reflect changes in left atrial pressure and may be associated with a fall in cardiac output. This increase in pulmonary capillary wedge pressure suggests that there is a high resistance to flow in the pulmonary circulation and that a lower level of PEEP should be used.

Adult↗