Table 3 lists patient characteristics 24 hours after the onset of mechanical ventilation. Survivors were more likely to be ventilator independent, and a higher proportion were awake and responsive. Nonsurvivors had lower blood pressure, a lower a/A ratio for oxygen, less frequently had improvement of pulmonary edema on chest roentgenogram, and were more likely to require vasoactive and antiarrhythmic medication; 93.5 percent of those requiring vasoactive medication at 24 hours had sustained a myocardial infarction.
Eleven survivors and 21 nonsurvivors (p<0.001) had pulmonary artery balloon flotation catheters. Most of these were inserted more than 12 hours after the onset of pulmonary edema. Pulmonary artery occlusion pressures were similar, 18.6 ±5.7 for survivors, and 21.0±4.0 for nonsurvivors.
Twenty patients had nuclear cardiac wall motion studies performed during their hospital admission for pulmonary edema (6.0 ±2.9 days after intubation). Fourteen patients had echocardiography, five of whom also had nuclear wall motion studies. The mean ejection fraction was 38.71 percent ±18.1 percent; 45.5 percent of the studies showed ejection fractions of 30 percent or less; 94 percent of studies showed hypokinesis of the ventricular wall.
The APACHE II score for those who died was 20.7 ±5.6 vs 24.5 ±6.7 for those who lived. No relationship between increasing APACHE II score and increasing mortality was observed.
Table 3—Clinical Characteristics 24 Hours after Onset of Mechanical Ventilation
|Survivors, % n = 56||Nonsurvivors, % n = 26*||P|
|A. Discrete variables|
|Awake and responsive||94.6||73.1||<0.01|
|Peak CPK >1000 U/mlt||8.9||40.6||<0.001|
|B. Continuous variables|
|Low HR*||79.6 ±14.2||88.4 ±25.8||NS|
|High HR*||104.0 ±20.4||126.3 ±20.8||<0.001|
|Low systolic BP$||120.5 ±23.5||88.4 ±29.1||<0.001|
|High systolic BP$||164.1 ±27.6||138.5 ±35.5||<0.001|
|Arterial pH||7.45 ±.05||7.45 ±.05||NS|
|Arterial Pco2||39.4 ±5.5||34.1 ±5.9||<0.001|
|a/A for 02||0.40 ±.15||0.30 ±.12||<0.005|
|BUN||35.3± 17.8||40.7 ±18.7||NS|