Aryl hydrocarbon hydroxylase activity in pulmonary alveolar macrophages and lymphocytes from lung cancer and noncancer patients: a correlation with family histories of cancer.

Aryl hydrocarbon hydroxylase (AHH) activity was measured in pulmonary alveolar macrophages (PAMs) and peripheral blood lymphocytes from cigarette smokers with and without primary lung cancer. Frequency distribution analysis of AHH induction ratios for the two groups revealed an increased number of individuals in the lung cancer patient group with high lymphocyte induction values (P less than 0.05). A similar increase was not shown for high-PAM AHH values in lung cancer patients (P greater than 0.2). When individual PAM and lymphocyte AHH values were compared between noncancer and lung cancer patients, a positive correlation was observed for noncancer patients (r=0.195, P less than 0.001), but no correlation of these values was noted for lung cancer patients. The lung cancer patients were divided into three subgroups of patients showing (I) high PAM and low lymphocyte AHH levels, (II) low PAM and low lymphocyte AHH levels, and (III) low PAM and high lymphocyte AHH levels. When the incidence of family history of cancer was compared for these subgroups, no family cancer history was recorded for persons in subgroup II; however, individuals in subgroups I and III presented family cancer history incidence of 9.5% and 39.3%, respectively. Patients in group III averaged 6 years younger than those in group I. These data suggest that familial factors may be identified among lung cancer patients and that these factors appear to associate as either a cause of an effect with the capacity of pulmonary alveolar macrophages and lymphocytes to be induced for AHH. The data support the hypothesis that high AHH values may be characteristic of lung cancer patients but show that enzyme values determined from a single tissue, either PAMs or lymphocytes, may not be appropriate for showing whether high AHH inducibility is correlated with lung cancer.

Effects of changes in arterial carbon dioxide tension on oxygen consumption during cardiopulmonary bypass.

The effects of changes in arterial carbon dioxide tension (PaCO2) on the oxygenation of tissues in 34 patients undergoing surgery for aortocoronary bypass were studied while temperature, systemic blood flow, and the delivery of oxygen to the peripheral tissues remained constant. Mixed venous and superior vena caval oxygen tensions (PvO2 and PsvcO2, respectively) and oxyhemoglobin saturations and the in vivo partial pressure of oxygen at which 50 percent of the hemoglobin is saturated (P50) increased with PaCO2, while peripheral vascular resistance, in vitro P50, the level of 2,3-diphosphoglyceric acid in the red blood cells, and the level of lactate in the blood remained constant. There was a close correlation between increases in PaCO2 and increases in PvO2 (r = 0.912; P less than 0.001) but not increases in PsvcO2 (r = 0.364; not significant). This indicated that the total-body consumption of oxygen diminished with increases in PaCO2 but that some regional redistribution of oxygen consumption occurred between the superior and inferior vena caval vascular beds. Since the level of lactate in the blood remained constant and since signs of metabolism acidosis did not develop, the reduced oxygen consumption due to increases in PaCO2 did not result in detectable increases in anaerobic metabolism.

The influence of PEEP on survival of patients in respiratory failure: a retrospective analysis.

Positive end expiratory pressure breathing (PEEP) is used to decrease morbidity and mortality in patients who are hypoxemic despite breathing oxygen in concentrations potentially toxic to their lungs. We reviewed the hospital course of 78 patients whose arterial oxygen tension (PaO2) was less than 70 torr despite a fraction of inspired oxygen (FiO2) of 1.0. Only 60 per cent of these patients were treated with PEEP and their clinical illnesses and severity of cardiopulmonary dysfunction were similar to those in patients not treated with PEEP. PEEP increased the length of survival from 4.2 to 9.2 days (P less than 0.05) whereas over-all survival, defined as hospital discharge, was similar at 31 per cent with and 26 per cent without PEEP. An improvement in PaO2 and decrease in shunt fraction following a trial of PEEP portends a favorable outcome, but its continued use appears to prolong life for a few days without affecting hospital mortality. Survival appears related more to the maintenance of adequate tissue oxygenation as manifested by a high mixed venous oxygen than to improved gas exchange as reflected by an increase in PaO2.