Kota G. Chetty

Improved exercise tolerance of the polycythemic lung patient following phlebotomy

The present study evaluated the effects of therapeutic phlebotomy on the exercise tolerance and the maximal carbon dioxide output of polycythemic patients with chronic obstructive pulmonary disease. Fifteen maximal exercise studies were performed before and after phlebotomy in patients with moderate to severe chronic obstructive pulmonary disease (mean forced expiratory volume in one second [FEV1]= 970 ml). After phlebotomy there were no significant differences in pulmonary function, blood gases, oxygen consumption, or carbon dioxide production at rest. However, after phlebotomy there was a significant increase in the exercise tolerance of the patients. The mean workload, the duration of exercise, the maximal oxygen consumption, the maximal carbon dioxide production, and the ventilation at maximal exercise all increased significantly. The improved exercise tolerance after phlebotomy appeared due to an increased cardiac output generated mainly through an increased stroke volume. We hypothesize that the increased stroke volume was due to a higher ejection fraction of the right ventricle secondary to a lower pulmonary artery pressure. This study provides further evidence that patients with chronic obstructive pulmonary disease who have polycythemia benefit by therapeutic interventions that maintain their hematocrits below 55 percent.

Effects of isosorbide dinitrate on pulmonary hypertension in chronic obstructive pulmonary disease.

Eighteen patients with chronic obstructive pulmonary disease with pulmonary hypertension were studied to assess the hemodynamic response to acute oxygen administration and to oral isosorbide dinitrate (ISDN). All 18 patients had baseline hemodynamic measurements and hemodynamic measurements during low‐flow nasal oxygen. Following a second baseline measurement, patients received either oral ISDN (11 patients) or placebo (7 patients) in a randomized, double‐blind protocol. Heart rate decreased with oxygen administration but there were no other significant hemodynamic changes. With oral ISDN, there was a significant fall in pulmonary artery and brachial artery pressure. Cardiac output, right atrial pressure, pulmonary wedge pressure, and pulmonary vascular resistance all fell but not significantly. We conclude that oral ISDN is effective in reducing pulmonary hypertension in patients with chronic obstructive pulmonary disease.

P pulmonale in status asthmaticus

We studied 129 patients during acute, severe asthmatic attacks. Electrocardiograms showed P pulmonale in 49% of patients who had an arterial carbon dioxide tension (PaCo2) greater than or equal to 45 mm Hg and an arterial pH less than or equal to 7.37, whereas P pulmonale was present in only 2.5% of asthmatics who had a PaCO2 less than or equal to 44 mm Hg and a pH greater than or equal to 7.38 (p less than 0.001). P wave and QRS axes were 79 +/- 8 degrees and 80 +/- 20 degrees, respectively, in the presence of P pulmonale. When P pulmonale disappeared, the P wave and QRS axes shifted significantly to the left (p less than 0.001). Electrocardiographic P pulmonale persisted 12 to 60 hr after correction of hypoxemia, hypercapnia, and acidosis. In 7 patients with P pulmonale and respiratory acidosis, cardiac catheterization demonstrated normal artery pressures (PAPs) measured relative to atmospheric pressure. In 12 of these peak inspiratory pulmonary artery transmural pressures (PATPs) were increased. Since increased right heart transumural pressures could result in chamber distention, these data are consistent with the hypothesis that reversible P pulmonale in status asthmaticus is explainable on the basis of markedly negative tidal pleural pressures and increased right heart transmural pressures.

Exercise Performance of Polycythemic Chronic Obstructive Pulmonary Disease Patients: Effect of Phlebotomies

The purpose of this study was to determine the effects of phlebotomy on the exercise tolerance and right and left ventricular ejection fraction of polycythemic patients with chronic obstructive pulmonary disease. Ten patients with COPD (mean FEV1 = 1.32 +/- 0.55 L) and polycythemia (mean Hct = 62 +/- 3 percent) were studied before and after their hematocrits had been reduced to approximately 50 percent. Post-phlebotomy the maximal oxygen consumption increased from 1.09 +/- 0.34 L/min to 1.26 +/- 0.43 L/min (p less than 0.05) and the maximum workload increased from 56.5 +/- 32.6 watts to 74.5 +/- 23.4 watts (p less than 0.05). The increase in the exercise tolerance appeared to be primarily due to an increased cardiac output at Emax. There was no relationship between the increases in the upright exercise capacity and changes in the supine ejection fractions of the right or left ventricular either at rest or during exercise.

Comparison of the effects of labetalol and hydrochlorothiazide on the ventilatory function of hypertensive patients with mild chronic obstructive pulmonary disease

Labetalol is a new adrenergic antagonist with both alpha- and beta-blocking effects. The effects of labetalol and hydrochlorothiazide on the hypertension and ventilatory function of patients with both hypertension and mild reversible chronic pulmonary disease were compared. In this double-blind study, 20 patients were randomly allocated to receive increasing doses of labetalol (100 to 400 mg three times a day) or hydrochlorothiazide (25 to 50 mg three times a day) over a four-week treatment period. Patients returned at weekly intervals for spirometry baseline, two hours after receiving the medication for the following week, and five minutes after an exercise test. Each treatment reduced the blood pressure significantly and to a comparable degree. There was no significant decrease in ventilatory function two hours after administration of the drug at any visit for either drug. Ventilatory function did not deteriorate significantly following exercise with either drug. With labetalol there was a progressive statistically significant decline in baseline forced expiratory volume in one second from 1,860 +/- 190 ml to 1,685 +/- 190 ml during the four-week study period, although no patient became symptomatic from shortness of breath. We conclude that labetalol is an effective antihypertensive agent that does not adversely effect ventilatory function immediately, but that may lead to a decline in ventilatory function when administered long-term.

Clinical InvestigationsExercise Performance of Polycythemic Chronic Obstructive Pulmonary Disease Patients: Effect of Phlebotomies

The purpose of this study was to determine the effects of phlebotomy on the exercise tolerance and right and left ventricular ejection fraction of polycythemic patients with chronic obstructive pulmonary disease. Ten patients with COPD (mean FEV1 = 1.32 +/- 0.55 L) and polycythemia (mean Hct = 62 +/- 3 percent) were studied before and after their hematocrits had been reduced to approximately 50 percent. Post-phlebotomy the maximal oxygen consumption increased from 1.09 +/- 0.34 L/min to 1.26 +/- 0.43 L/min (p less than 0.05) and the maximum workload increased from 56.5 +/- 32.6 watts to 74.5 +/- 23.4 watts (p less than 0.05). The increase in the exercise tolerance appeared to be primarily due to an increased cardiac output at Emax. There was no relationship between the increases in the upright exercise capacity and changes in the supine ejection fractions of the right or left ventricular either at rest or during exercise.

Comparison of noninvasive with hemodynamic data in patients with pulmonary hypertension due to chronic obstructive pulmonary disease.

Twenty-one patients with chronic obstructive pulmonary disease were studied with right heart catheterization. The mean pulmonary artery pressure (PAP) was compared with several noninvasive tests. The pulmonary lobar diameter/ thoracic ratio correlated with the PAP, r = 0.677, P < 0.01. The oxygen saturation and pH were used to derive a calculated value for PAP. The calculated PAP correlated with PAP values measured below 40 mm Hg, r = 0.787, P < 0.01 but correlated very poorly with PAP values measured above 40 mm Hg. The electrocardiogram revealed at least one criterion for right ventricular abnormality in all 18 patients with pulmonary hypertension, but was too nonspecific to correlate with PAP. The hemoglobin concentration did not correlate with PAP. There was such wide variation between the measured PAP and the various noninvasive tests that these noninvasive tests could not be used to accurately predict the PAP in an individual patient.

Respiratory Infections Due to Group C Streptococci

Lancefield group C streptococci are a rare cause of human infections. The spectrum of respiratory disease includes pharyngitis, tonsillitis, sinusitis, pneumonia, pleural effusion, and empyema. Pneumonia may progress rapidly to form effusion and empyema. Mortality rates of 20% to–30% have been reported with bacteremia. We describe a patient who developed a massive empyema due to Streptococcus dysgalactiae and review the literature on group C streptococcal pulmonary infections. The empyema was multiloculated and required thoracotomy drainage. At surgery, most of the right lung was found to be destroyed with necrosis and suppuration. The patient survived with prolonged penicillin treatment. On further investigation, he was found to have adenocarcinoma of the lung.

Exercise-induced changes in left ventricular function after phlebotomy in patients with polycythemic COPD.

The exercise capacity of polycythemic COPD patients has been shown to improve after phlebotomy, possibly because of reduction of ventricular afterload by decreased blood viscosity, resulting in increased cardiac output. Ten patients with polycythemic COPD and mean hematocrit 62% were studied at rest and during exercise before and after reduction of mean hematocrit to 50% by repeated phlebotomy. Pulmonary function was evaluated by physiologic exercise testing on a bicycle ergometer. Cardiac function was evaluated by rest and exercise RNVG. Significant increase in exercise tolerance and maximal oxygen uptake at peak exercise, with significant reduction in mean systemic BP, were demonstrated. Ejection fractions did not change, but dV/dt for ejection from the left ventricle at peak exercise improved significantly. Mean SV counts, ESV counts, and EDV counts were measured and the fractional increase with exercise compared for prephlebotomy and postphlebotomy, assuming that resting volumes would not change. ESV counts and EDV counts were both proportionately, though not significantly, reduced postphlebotomy. The data tend to support the hypothesis that the afterload on the left ventricle is reduced, with resulting improved myocardial contractility and left ventricular function. Improved peripheral oxygen uptake may also be a factor.