Respiration; international review of thoracic diseases
-
The type and distribution of pulmonary vascular lesions in 23 cases of primary pulmonary hypertension were reviewed. 15 cases were classified as plexogenic arteriopathy. The remaining cases displayed thromboembolic lesions. ⋯ In the plexogenic group, mixed concentric and eccentric intimal fibrosis coexisted. Therefore, in the present study, we propose an objective descriptive approach to the diagnosis of hypertensive pulmonary vascular disease, to correlate morphology and function.
-
Using a constant-volume infant whole-body plethysmograph containing a heated rebreathing bag, we have been able to measure airway resistance (Raw) throughout the respiratory cycle using a computer-based technique. Data from the plethysmograph transducers are sampled at 60 Hz for the calculations and Raw is calculated at each point sampled during the breath, with appropriate corrections for absolute lung volume. It was found that in most cases Raw varied less with respect to tidal volume than to tidal flow. ⋯ These included an elevated but relatively constant resistance, a progressively rising expiratory resistance, and in 3 infants with laryngomalacia, a progressively rising inspiratory resistance. It was also found that the dynamic performance of the rebreathing bag was such that considerable errors would occur if apparatus resistance was assumed to be constant and so the actual apparatus resistance at each point was subtracted from the total resistance to give Raw. In conclusion, Raw is not constant throughout the respiratory cycle in infants and the pattern of change conveys additional information.
-
Comparative Study
Comparison of the effect of continuous positive airway pressure and blowing bottles on functional residual capacity after abdominal surgery.
In two groups of comparable patients undergoing elective abdominal surgery, functional residual capacity (FRC) was measured preoperatively and on the first 2 days after surgery. One group was treated by regular application of continuous positive airway pressure (CPAP), the other group by bottle blowing (BB). In both groups there was a significant reduction of FRC on the first postoperative day. ⋯ BB resulted in especially high expiratory and total resistive work. It is concluded that CPAP and BB increase temporarily the reduced FRC after abdominal surgery. CPAP was much better tolerated by the patients due to the lower resistive work of breathing.
-
We have studied the role of 5-hydroxytryptamine (5-HT) in monocrotaline pulmonary hypertension and chronic hypoxic pulmonary hypertension in rats using p-chlorophenylalanine (PCPA) which inhibits 5-HT synthesis. We measured right ventricular mean systolic pressure (Prvs), right ventricular hypertrophy, medial thickness of muscular pulmonary arteries, and muscularization of pulmonary arterioles 17 days after a single dose of monocrotaline (60 mg/kg) and after 26 days of chronic hypobaric hypoxia (380 mm Hg). In monocrotaline pulmonary hypertension, pretreatment with PCPA (500 mg/kg) was associated with significant reductions (p less than 0.05) in Prvs (29%), right ventricular hypertrophy (33%), and medial thickness of muscular pulmonary arteries (14%). In chronic hypoxic pulmonary hypertension, pretreatment with PCPA was associated with significant reductions in Prvs (20%), right ventricular hypertrophy (28%), medial thickness of muscular pulmonary arteries (14%), and muscularization of pulmonary arterioles (47%). 5-HT may play a role in the development of monocrotaline pulmonary hypertension and chronic hypoxic pulmonary hypertension in rats.
-
In order to assess the effect of breathing pattern on measurements of dead space ventilation (VD/VT) during exercise, we studied 6 patients with the complaint of exertional dyspnea. They had essentially normal resting pulmonary function studies and the only abnormality noted during an initial exercise study was an elevated VD/VT associated with a rapid respiratory rate. ⋯ During the exercise study with coaching, the VD/VT response was normal. We conclude that breathing pattern during exercise influences VD/VT and that an increase in total minute ventilation which is accomplished by a preferential increase in respiratory rate may result in an abnormally high VD/VT.