ABSTRACT
Twenty-five normal subjects, 14 non-smokers and 11 smokers, passively expired into a spirometer after a maximal active inspiration, and after a passive inflation of the chest by a pressure cycled intermittent positive-pressure breathing (IPPB) machine. Acceptable passive expirations could be performed by all subjects after a passive inspiration but by only 12 after an active inspiration. Expired volume was found to change exponentially with time (r greater than 0.98), and the time constant of passive expiration (Tp) was obtained. There was no significant difference between the smokers and non-smokers in age, sex, forced vital capacity, FEV1 FEV1/FVC%, maximum mid-expiratory flow rate, maximum expiratory flow at 50% and 25% of the vital capacity, or the magnitude of the fall in the dynamic compliance with increasing frequency of breathing (Cdyn/f). Tp in smokers (1.06 +/- 0.47 SD) was significantly longer than in the non-smokers (0.65 +/- 0.25 SD P less than 0.02). Tp had a significant correlation with Cdyn/f(Tp = 0.6 + 161.81 Cdyn/f +/- 0.38 SE, r = 0.49, P less than 0.02). We conclude that satisfactory passive expiratory spirograms can be easily obtained after a mechanically assisted passive inspiration. Tp thus obtained is determined by the intrinsic properties of the respiratory system (lung plus thorax), and is significantly prolonged in smokers compared with non-smokers when other studies of pulmonary function including frequency dependence of compliance are unchanged.
Subject(s)
Lung/physiology , Respiratory Function Tests/methods , Adult , Esophagus/physiology , Female , Functional Residual Capacity , Humans , Intermittent Positive-Pressure Breathing , Lung/physiopathology , Lung Compliance , Lung Diseases/diagnosis , Male , Respiration , Smoking/physiopathology , SpirometryABSTRACT
The alveolar to arterial oxygen pressure difference (AaDO2) and pulmonary venous admixture (Qs/Qt) were measured in 32 patients with chronic obstructive pulmonary disease during right heart catheterization at inspired oxygen concentrations (FIO2) of 21, 24, 28, 35, and 40%. Patients without chronic hypercapnia (PaCO2 is less than 45 torr, group A) had Qs/Qt less than 25% while breathing room air; their AaDO2 rose at a rate of 3 torr for each percent increase in FIO2. In those with chronic hypercapnia (PaCO2 greater than 44 torr., (group B), THE Qs/Qt was always greater than 24% during air breathing and the AaDO2 rose at a rate of 5 torr for each percentage increase in FIO2. These changes should be considered in the interpretation of the AaDO2 in patients with COPD in whom the FIO2 is changed during the course of therapy. The Qs/Qt fell curvilinearly with increasing FIO2 but the rates of fall were quantitatively different in groups A and B. A physiological explanation for the changes in Qs/Qt and ADO2 which result from changes in FIO2 is presented.
Subject(s)
Lung Diseases, Obstructive/blood , Oxygen/blood , Arteries , Carbon Dioxide/blood , Chronic Disease , Female , Humans , Lung Diseases, Obstructive/therapy , Male , Middle Aged , Oxygen/therapeutic use , Pulmonary Alveoli , VeinsABSTRACT
Simultaneous hemodynamic, ventilatory, and blood gas studies were performed in 16 men with congestive heart failure before and during infusion of sodium nitroferricyanide (nitroprusside). The cardiac index increased from 2.00+/-0.16 L/min/sq m (SE) to 2.38+/-0.14 L/min/sq m, and the total pulmonary and systemic peripheral resistances fell from 928+/-123 to 494+/-57 dynes sec cm-5 and from 2,208+/-210 to 1,558+/-121 dynes sec cm-5, respectively. Both systemic and pulmonary arterial decreased during infusion of sodium nitroferricyanide, and the mixed venous oxygen pressure increased. There was no change in total or alveolar ventilation, arterial carbon dioxide tension, pH, or base excess; however, the mean arterial oxygen pressure (PaO2) decreased from 74+/-3 mm Hg to 68+/-3 mm Hg and the venous admixture effect increased from 8+/-1% to 13+/-2%. We conclude that the decrease in PaO2 during infusion of sodium nitroferricyanide resulted from a worsening of the ventilation-perfusion relationships due to increased perfusion of underventilated pulmonary units.
Subject(s)
Ferricyanides/therapeutic use , Heart Failure/drug therapy , Hemodynamics/drug effects , Nitroprusside/therapeutic use , Adult , Aged , Blood Pressure/drug effects , Cardiac Catheterization , Heart Rate/drug effects , Humans , Infusions, Parenteral , Male , Middle Aged , Nitroprusside/administration & dosage , Oxygen Consumption/drug effects , Pulmonary Artery , Venous Pressure/drug effects , Ventilation-Perfusion Ratio/drug effectsABSTRACT
Serum angiotensin converting enzyme (ACE) activity was measured in 10 patients with early active sarcoidosis, nine patients with inactive or resolving sarcoidosis, 10 patients with malignant pulmonary neoplasms, eight patients with miscellaneous lung diseases, and 18 control subjects with no known pulmonary disease. The serum ACE activity, expressed in units/ml, in control subjects (5-88 +/- 1-84), was no different from the values obtained in patients with inactive or resolving sarcoidosis (6-85 +/- 2-48) or miscellaneous lung diseases (4-61 +/- 3-20). However, the ACE activity was found to be markedly raised in patients with early active sarcoidosis (13-49 +/- 2-52), and there was no overlap with control values. The patients with pulmonary neoplasms had significantly lower values of serum ACE activity than the control subjects (2-80 +/- 3-30).
