The impact of diaphragm management on prolonged ventilator support after thoracoabdominal aortic repair

PURPOSE: The relationship of the division of the diaphragm during thoracoabdominal aortic repair to prolonged ventilator support has not been studied. The purpose of this study was (1) to determine whether preservation of diaphragm integrity has a significant effect on postoperative ventilator duration and (2) to elucidate other pulmonary risk factors related to thoracoabdominal aortic surgery and to study the relationship of these factors to the intact diaphragm technique. METHODS:Between February 1991 and January 1997, we repaired 397 descending and thoracoabdominal aortic aneurysms. Descending thoracic aneurysms were not included in the study because their repair does not include the diaphragm. A total of 256 patients participated in this study. The diaphragm was divided in 150 patients and left intact in 106 patients. Examined as potential risk factors were patient demographics, history and physical findings, aneurysm extent, urgency of the procedure, acute dissection, cross-clamp time, homologous and autologous blood product consumption, and adjunctive operative techniques. FEV1 also was considered in the 197 patients for whom preoperative spirometry was available. Prolonged mechanical ventilation was defined as ventilator support for >72 hours. Data were analyzed by univariate contingency table and multiple logistic regression methods. RESULTS: Increasing age (odds ratio [OR], 1.02/y; P <.02), current smoking (OR, 2.6; P <.0008), total cross-clamp time (OR, 1.0/min; P <.008), units packed red blood cells transfused (OR, 1.06/unit; P <.008), and division of the diaphragm (OR, 2.03; P <.02) were significant, independent predictors of prolonged ventilation. Sixty-seven percent of patients (71 of 106) whose diaphragms were preserved were extubated in <72 hours compared with 52% of patients (78 of 150) who underwent diaphragm division (OR, 0.53; P <.02). CONCLUSION: Independently of well known pulmonary risk factors, an intact diaphragm during thoracoabdominal aortic repair results in a higher probability of early ventilator weaning.     

Growth hormone improves body composition, fat utilization, physical strength and agility, and growth in Prader-Willi syndrome: A controlled study

BACKGROUND: Obesity and hypotonia in children with Prader-Willi syndrome (PWS) are accompanied by abnormal body composition and diminished energy expenditure resembling a growth hormone deficient state. Hypothalamic dysfunction in PWS often includes decreased growth hormone (GH) secretion, suggesting a possible therapeutic role for exogenous GH treatment. OBJECTIVES AND METHODS: After 6 months of observation to determine baseline growth rate, and with the use of a 12-month randomized controlled study design, the effects of GH treatment (1 mg/m2/d) on growth, body composition, strength and agility, pulmonary function, resting energy expenditure (REE), and fat utilization were assessed in 54 children with PWS (n = 35 treatment and n = 19 control). Percent body fat and bone mineral density were measured by dual x-ray absorptiometry. Indirect calorimetry was used to determine REE and to calculate respiratory quotients. RESULTS: Stimulated levels of GH in response to clonidine testing were low in all patients (peak, 2.0 ng/mL). After 12 months, GH-treated subjects showed significantly increased height velocity Z scores (mean, 1.0 1.7 to 4.6 2.9; P <.001), decreased percent body fat (mean, 46.3% 8.4% to 38.3% 10.7%; P <.001), and improved respiratory muscle function, physical strength, and agility (sit-ups, weight-lifts, running speed, and coordination). A significant decline in respiratory quotients occurred during GH therapy (0.81 to 0.77, P <.001), but total REE did not change. CONCLUSIONS: GH treatment of children with PWS accelerated growth, decreased percent body fat, and increased fat oxidation but did not significantly increase total REE. Improvements in respiratory muscle strength, physical strength, and agility also occurred, suggesting that GH treatment may have value in reducing some physical disabilities experienced by children with PWS.     

Conversion of 3-chlorocatechol by various catechol 2,3-dioxygenases and sequence analysis of the chlorocatechol dioxygenase region of Pseudomonas putida GJ31

Pseudomonas putida GJ31 contains an unusual catechol 2,3-dioxygenase that converts 3-chlorocatechol and 3-methylcatechol, which enables the organism to use both chloroaromatics and methylaromatics for growth. A 3.1-kb region of genomic DNA of strain GJ31 containing the gene for this chlorocatechol 2,3-dioxygenase (cbzE) was cloned and sequenced. The cbzE gene appeared to be plasmid localized and was found in a region that also harbors genes encoding a transposase, a ferredoxin that was homologous to XylT, an open reading frame with similarity to a protein of a meta-cleavage pathway with unknown function, and a 2-hydroxymuconic semialdehyde dehydrogenase. CbzE was most similar to catechol 2,3-dioxygenases of the 2.C subfamily of type 1 extradiol dioxygenases (L. D. Eltis and J. T. Bolin, J. Bacteriol. 178:5930-5937, 1996). The substrate range and turnover capacity with 3-chlorocatechol were determined for CbzE and four related catechol 2,3-dioxygenases. The results showed that CbzE was the only enzyme that could productively convert 3-chlorocatechol. Besides, CbzE was less susceptible to inactivation by methylated catechols. Hybrid enzymes that were made of CzbE and the catechol 2, 3-dioxygenase of P. putida UCC2 (TdnC) showed that the resistance of CbzE to suicide inactivation and its substrate specificity were mainly determined by the C-terminal region of the protein.     

Analysis of heart-rate variability: a noninvasive predictor of death and poor outcome in patients with severe head injury

BACKGROUND: Analysis of heart-rate variability (HRV) is a promising new technique for noninvasive quantification of autonomic function. We measured HRV in patients with severe head injury to assess its potential as a monitoring tool. METHODS: Analysis of HRV was prospectively done on all intensive care unit patients. Concurrent data on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were collected. Registry data were reviewed to identify patients with severe head injury, defined as Head/Neck Abbreviated Injury Scale score > or = 4. Mortality, likelihood of discharge to home, ICP, and CPP were compared between patients with abnormal HRV and those without. RESULTS: Low HRV was associated with increased mortality and decreased rate of discharge to home. Abnormal HRV was associated with episodes of increased ICP and decreased CPP. CONCLUSION: Assessment of HRV is a noninvasive method that can be widely used. Abnormal HRV was associated with poor outcome and altered cerebral perfusion. Monitoring of HRV may improve outcome by allowing earlier detection and treatment of intracranial pathology.