Accuracy of portable chest radiography in the critical care setting. Diagnosis of pneumonia based on quantitative cultures obtained from protected brush catheter.

Sixty-six supine portable chest radiographs done on the day of bronchoscopy in 62 critical care unit patients suspected of having pneumonia were examined in a blinded fashion by two radiologists. Quantitative culture results obtained from protected brush catheter (PBC) specimens were compared with chest radiograph scores. For one observer, the sensitivity of the chest radiograph for predicting the presence of positive culture results was 0.60, specificity was 0.29, overall agreement was 0.41, positive predictive value was 0.34, and negative predictive value was 0.55. For the second observer, the values were as follows: sensitivity, 0.64; specificity, 0.27; overall agreement, 0.41; positive predictive value, 0.35; and negative predictive value, 0.55. The kappa statistic was calculated at 0.27 indicating marginal interobserver reproducibility. We conclude the portable chest radiograph in the critical care setting is not accurate in predicting the presence of pneumonia when the diagnosis is based on quantitative cultures obtained from protected brush catheter specimens.

Theophylline delays skeletal muscle fatigue during progressive exercise.

In this study, 31P nuclear magnetic resonance spectroscopy (NMRS) was used to examine the effect of theophylline on human forearm muscle metabolism during progressive exercise. Six healthy men (37 +/- 14 yr of age) were assigned to either a control (CTRL) group (n = 3), or a theophylline treatment (THEO) group (n = 3). Each subject performed two dynamic wrist flexion exercise tests to fatigue, with at least 72 h separating each trial. The THEO group repeated the protocol after receiving 300 mg of sustained-release theophylline every 12 h. 31P spectra were acquired every 36 s throughout exercise, and the relative contributions of the phosphate metabolites and pH were determined. Power output at the onset, or threshold of intracellular acidosis (IT), was identified for each subject from changes in phosphocreatine (PCr) metabolism and pH. Power at maximal exercise and at the IT was found to be reproducible in the CTRL group. After theophylline administration, the maximal power attained by the THEO group increased significantly by 19% (p < 0.05), from 2.25 +/- 0.2 to 2.68 +/- 0.15 W. A similar trend occurred in the onset of the IT, which was also prolonged by 19%, from 1.33 +/- 0.18 to 1.58 +/- 0.22 W. Therapeutic concentrations of theophylline significantly increased the endurance of the forearm musculature, apparently by delaying the onset of intracellular metabolic acidosis. These findings suggest an enhancement of oxidative capacity of the muscle.

Right phrenic nerve injury in orthotopic liver transplantation.

Right hemidiaphragm paralysis has been previously documented in patients after orthotopic liver transplantation (OLT) and it may contribute to the development of postoperative pulmonary problems. It has been postulated that a crush injury to the right phrenic nerve during OLT is the cause of dysfunction of the right hemidiaphragm. To assess the incidence and effect of right phrenic nerve injury after OLT, we prospectively studied 48 adult liver recipients. Twelve patients who underwent liver resection (LR), in whom the suprahepatic vena cava was not clamped, were used as a comparison group. Diaphragm excursion by ultrasound and pulmonary function were performed preoperatively and postoperatively; transcutaneous phrenic nerve conduction studies were performed postoperatively. Right phrenic nerve injury and hemidiaphragm paralysis occurred in 79% and 38% of the liver recipients but not after LR. Conduction along the right phrenic nerve was absent in 53% and reduced in another 26%. Left phrenic nerve conduction and left hemidiaphragm excursion were normal in both liver recipients and the patients who had LR. Liver recipients with no conduction in the right phrenic nerve had a significantly greater decrease in vital capacity in the supine position (29 +/- 9.8%) compared with those with some conduction (14 +/- 6.9%, P < 0.001). However, neither the time on the ventilator nor the hospital stay was significantly different in the latter two groups. Complete recovery of phrenic nerve conduction and diaphragm function took until nine months in some patients. Right phrenic nerve injury is common after OLT and it is the cause of right hemidiaphragm dysfunction.