Frequency of chronic obstructive airways disease and pulmonary hypertension in patients with acute inferior myocardial infarction with or without right ventricular infarction.

OBJECTIVE: Factors influencing the incidence of right ventricular infarction among patients with acute inferior myocardial infarction have not yet been fully established. Chronic obstructive airways disease and right ventricular hypertrophy were suggested as possible predisposing factors but no definite evidence was shown. This study analyses the frequency of chronic obstructive airway disease and of Doppler assessed pulmonary hypertension among patients with acute inferior myocardial infarction with or without right ventricular infarction. DESIGN AND PATIENTS: Sixty consecutive patients with acute inferior myocardial infarction were prospectively enrolled into the study. MEASUREMENTS: Standard 12-lead ECG with right precordial leads (V3-6R) were recorded on admission to the Coronary Care Unit and on days 2 and 3. Doppler echocardiography was performed within 48 h after the onset of myocardial infarction and repeated 6 weeks later together with a pulmonary function test. Routine biochemical and clinical data were collected. RESULTS: Right ventricular infarction occurred in 35% of patients with acute inferior myocardial infarction. No differences in respiratory indices of chronic obstructive airways disease or in Doppler echocardiography parameters of pulmonary hypertension were revealed among patients with and without right ventricular infarction. Peak total creatine kinase level and creatine kinase myocardial isoenzyme levels were higher in patients with right ventricular infarction than in those without (2925 +/- 1321 vs. 1682 +/- 1216 U/l; P < 0.001 and 207 +/- 108 vs. 127 +/- 102 U/l; P < 0.05, respectively). CONCLUSIONS: In the course of acute inferior myocardial infarction, the frequencies of chronic obstructive airways disease and/or pulmonary hypertension were not higher among patients with right ventricular infarction than among those without right ventricular infarction. Thus, history of chronic obstructive airways disease and/or pulmonary hypertension do not necessitate specific precautions in respect of right ventricular infarction.

Relationship of the ECG with ventilatory function tests in chronic obstructive lung disease (COLD) in Nigerians.

Although the most objective assessment of the severity of COLD is done by spirometer, this is not as readily available in Nigeria as the electrocardiograph, thus the ECG is often used to assess it. This study examines the relationship between the ECG findings and FEV 1 obtained by spirometry and expressed as a proportion predicted for age and sex in 92 Nigerians with COLD of which 39 had associated pulmonate. There was an inverse relationship between the mean electrical axis of the P wave on the ECG and the FEV 1 of predicted. The axis was more positive (82 +/- 12 degrees) among those with FEV 1 less than 50% of predicted (group 1) and this decreased progressively with increasing FEV 1 to 72 +/- 14 degrees in those with FEV 1 between 50-70% (group 2) and 67 +/- 16 degrees in those with FEV 1 greater than 70% (group 3). There was also a significant relationship between FEV 1 and the development of cor pulmonale and 71.4% of those who had the lowest FEV 1 (group 1) had cor pulmonale while the proportion decreased with the reduction in the severity of airway obstruction. A rightward P wave axis greater than 80% was statistically significant associated with development of cor pulmonale (X2 = 29.5 (P < 0.001) of those with COLD and cor pulmonale, 72.2% had a P wave axis greater than 80%. Only 13.2% of those with COLD alone had a P wave axis greater than 80 degrees. Cardiac arrhythmias were present in 28 patients, ventricular (VA) in 23 cases, and atrial (AA) in 7 cases. Both AA and VA were associated with more severe airway obstruction. All 3 patients who had atrial fibrillation (AF) and FEV 1 below 50% of predicted (group 1) and had cor pulmonale while 2 of the remaining 4 with AA also were in group 1 and the remaining 2 in group 2. The distribution of ventricular arrhythmias (VA) showed that 10 (43.5%) were in group 1, 9 (39.1%) in group 2, and 2 (8.7%) in group 3. Both VA and AA were also significantly related to the development of cor pulmonale. A P wave amplitude greater than 2.5 mm was significantly related to the development of clinical cor pulmonale X2 = 24.6 P < 0.001. The results show that ECG findings correlate well with spirometric assessments of FEV 1 and clinical severity in Nigerians with COLD and are, therefore, useful where spirometry is unavailable.

Variability of inspired oxygen concentration with nasal cannulas.

BACKGROUND: The likely values of inspired oxygen concentration (FIO2) of patients with chronic obstructive pulmonary disease breathing via nasal cannulas have not been assessed previously. METHODS: Seven patients with chronic obstructive lung disease and seven healthy subjects were studied while breathing oxygen via nasal cannulas or fixed performance (Venturi) or uncontrolled (MC) oxygen masks. Breath to breath values of FIO2 were calculated by extrapolation from expired oxygen and carbon dioxide concentrations on the basis of the oxygen-carbon dioxide relationship and on the assumption of a respiratory exchange ratio (R) of 0.8. RESULTS: In both groups of subjects the average values of FIO2 with nasal cannulas at 1 and 2 l min-1 were of a similar order to those achieved with 24.5% and 28% Venturi masks, but variations within and between subjects in both groups breathing via nasal cannulas were considerable and similar to those found with MC masks. In the seven patients with chronic obstructive lung disease breathing via nasal cannulas at 2 l min-1 the average FIO2 varied from 23.7% to 34.9%. CONCLUSIONS: "Typical" values of FIO2 quoted with nasal cannulas can mislead. The results confirm that this mode of oxygen delivery is unsatisfactory if precise control of inspired oxygen is desired.