摘要:

Background:We previously demonstrated a markedly dependent distribution of ventilator-induced lung injury in oleic acid-injured supine animals ventilated with large tidal volumes and positive end-expiratory pressure ≥10 cm H2O. Because pleural pressure distributes more uniformly in the prone position, we hypothesized that the extent of injury induced by purely mechanical forces applied to the lungs of normal animals might improve and that the distribution of injury might be altered with prone positioning.Objective:To compare the extent and distribution of histologic changes and edema resulting from identical patterns of high end-inspiratory/low end-expiratory airway pressures in both supine and prone normal dogs.Design/Setting:We ventilated 10 normal dogs (5 prone, 5 supine) for 6 hrs with identical ventilatory patterns (a tidal volume that generated a peak transpulmonary pressure of 35 cm H2O when implemented in the supine position before randomization, positive end-expiratory pressure = 3 cm H2O). Ventilator-induced lung injury was assessed by gravimetric analysis and histologic grading.Measurements and Main Results:Wet weight/dry weight ratios (WW/DW) and histologic scores were greater in the supine than the prone group (8.8 ± 2.8 vs. 6.1 ± 0.7;p= .01 and 1.4 ± 0.3 vs. 1 ± 0.3;p= .037, respectively). In the supine group, WW/DW and histologic scores were significantly greater in dependent than nondependent regions (9.4 ± 1.9 vs. 6.7 ± 0.9;p= .01 and 2.0 ± 0.4 vs. 0.9 ± 0.4;p= .043, respectively). In the prone group, WW/DW also was greater in dependent regions (6.7 ± 1.1 vs. 5.8 ± 0.5;p= .054), but no significant differences were found in histologic scores between dependent and nondependent regions (p= .42).Conclusion:In this model of lung injury induced solely by mechanical forces, the prone position resulted in a less severe and more homogeneous distribution of ventilator-induced lung injury. These results parallel those previously obtained in oleic acid-preinjured animals ventilated with higher positive end-expiratory pressure.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objective:To compare the short-term effects of inhaled nitric oxide (NO) and prone positioning in improving oxygenation in acute respiratory distress syndrome (ARDS).Methods:Charts of consecutive ARDS patients (lung injury score >2) during a 2-yr period, tested for both inhaled NO and prone positioning efficacy were retrospectively reviewed. Variations in the PaO2/FIO2ratio induced by inhaled NO and prone positioning were evaluated.Measurements and Main Results:Twenty-seven patients (age, 42 ± 17 yrs) were included. Simplified Acute Physiology Score II was 45 ± 14. Mortality rate in the intensive care unit was 63%. The causes of ARDS were pneumonia (n = 14), extra-lung infection (n = 5), and noninfectious systemic inflammatory response syndrome (n = 8). Lung injury score was 2.7 ± 0.3. At baseline, before the initiation of inhaled NO, the PaO2/FIO2ratio was 97 ± 46 torr and before prone positioning, 92 ± 26 torr. Variations in the PaO2/FIO2ratio were lower at start of NO therapy (11 ± 4 ppm) than that observed at prone positioning initiation (23 ± 31 vs. 62 ± 78 torr, p < .05). An increase in variations in the PaO2/FIO2ratio of > 15 torr was associated with prone positioning in 16 patients (59%) and with NO inhalation in 13 patients (48%) (not significant). An increase in variations in the PaO2/FIO2ratio of > 15 torr was associated with both techniques in only six patients (22%). There was no correlation between the response to prone positioning and the response to inhaled NO (r2= .005;p= .73).Conclusions:Prone positioning improves hypoxemia significantly better than does inhaled NO. The response to one technique is not predictive of the response to the other technique.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:Atrial fibrillation remains a significant source of morbidity after coronary artery bypass grafting (CABG). Whether cardiopulmonary bypass (CPB) temperature influences the occurrence of postoperative atrial fibrillation in CABG patients has not been specifically examined. In the present study, we reviewed postoperative data from patients who were prospectively randomized to mild or moderate hypothermic CPB for elective CABG to determine the incidence of postoperative atrial fibrillation.Design:Randomized, single center, observational study.Setting:Tertiary university medical center.Patients:Adults undergoing elective CABG surgery.Interventions:Enrolled patients were prospectively randomized to mild (34°C [93.2°F]) or moderate (28°C [82.4°F]) hypothermic CPB.Measurements and Main Results:The incidence of postoperative atrial fibrillation was determined by review of ICU and hospital records. There was a significantly higher incidence of atrial fibrillation in the moderate compared with the mild hypothermic CPB group. Patients who had postoperative atrial fibrillation were significantly older than those without atrial fibrillation. Furthermore, a significant increase in the relative risk of developing postoperative atrial fibrillation was found for both age and CPB temperature.Conclusions:Our results indicate that the temperature of systemic cooling during CPB is an important factor in the development of atrial fibrillation after CABG surgery. In addition, this study confirms that increasing age is a significant determinant of postoperative atrial fibrillation.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objective:To evaluate the effects of a heat and moisture exchanger and a heated humidifier on respiratory mucus and transportability by cilia and cough in patients undergoing invasive mechanical ventilation (up to 72 hrs).Design:Prospective, randomized, clinical study.Setting:General intensive care unit and university research laboratory.Patients:A total of 32 consecutive patients with acute respiratory failure, who were intubated and mechanically ventilated in the intensive care unit setting, were enrolled in the study.Interventions:Patients were randomly assigned to receive as a humidifying system a heat and moisture exchanger (HME) or heated humidified water (HHW) at the onset of mechanical ventilation (time 0). Respiratory mucus samples were collected by suction using a sterile technique at time 0, 24, 48, and 72 hrs of mechanical ventilation.Measurements and Main Results:Eleven patients were excluded from this study because of either extubation or death before 72 hrs of mechanical ventilation, leaving 12 patients in the HME group and nine patients in the HHW group. Ventilatory variables including minute volume, mean airway pressure, positive end-expiratory pressure, FIO2, as well as PaO2/FIO2ratio, fluid balance (last 6 hrs), furosemide, and inotrope administration (last 4 hrs) were recorded.In vitromucus transportability by cilia was evaluated on the mucus-depleted frog palate model, and the results were expressed as the mucus transport rate. Cough clearance (an estimation of the interaction between the flow of air and the mucus lining the bronchial walls) was measured using a simulated cough machine, the results being expressed in millimeters. Mucus wettability was measured by the contact angle between a mucus sample drop and a flat glass surface. Mucus rheologic properties (mechanical impedance [log G*] and the ratio between viscosity and elasticity [tan δ]) were measured using a magnetic microrheometer at 1 and 100 cGy/sec deformation frequency. The two humidification groups were comparable in terms of the Acute Physiology and Chronic Health Evaluation II score, age, gender, ventilatory variables, fluid balance, use of inotropes, and furosemide.Conclusion:Ours results indicate that air humidification with either HME or HHW at 32°C (89.6°F) has similar effects on mucus rheologic properties, contact angle, and transportability by cilia in patients undergoing mechanical ventilation, except for transportability by cough, which diminished after 72 hrs of mechanical ventilation in the HME group (p= .0441).

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:To evaluate the cardiovascular response and acute stress reaction after arousal induced by a benzodiazepine antagonist, flumazenil, in patients sedated with midazolam.Design:Prospective study.Setting:Emergency center in a university hospital.Patients:A total of 12 patients were ventilated mechanically under sedation with midazolam.Interventions:We monitored the consciousness level, heart rate, systemic blood pressure, pulmonary artery pressure, and pulmonary artery occlusion pressure before and after a bolus injection of 0.5 mg of flumazenil. The score for the consciousness level represents the sum of the scores for eye opening and best motor response, as determined by the Glasgow Coma Scale. We measured the cardiac output, concentrations of norepinephrine, epinephrine, and 3-methoxy-4-hydroxyphenylethyleneglycol in plasma, and concentration of cortisol in serum. We calculated the left ventricular ejection fraction, cardiac index, systemic vascular resistance index, pressure-rate product, systemic oxygen delivery, and systemic oxygen consumption at 0, 10, 30, and 60 mins after injection of flumazenil.Measurements and Main Results:The serum benzodiazepine's receptor binding activity in serum was in the range from 50 to 1000 ng/mL before injection of flumazenil. Flumazenil improved the consciousness level from 6.7 ± 2.0 to 8.9 ± 1.6 and induced transient elevations in heart rate, blood pressure, systolic pulmonary artery pressure, and pulmonary artery occlusion pressure. Left ventricular ejection fraction, oxygen delivery index, and pressure-rate product increased significantly, from 61% ± 8%, 640 ± 170 mL/min/m2, and 13,300 ± 2600 mm Hg/min at 0 mins to 67% ± 5%, 710 ± 220 mL/min/m2, and 16,500 ± 4400 mm Hg/min at 10 mins, respectively. Concentrations of norepinephrine and epinephrine in plasma increased significantly, from 890 ± 840 pg/mL and 220 ± 360 pg/mL, respectively, at 0 mins to 990 ± 850 pg/mL and 270 ± 300 pg/mL, respectively, at 10 mins. There were no significant changes in the plasma concentration of 3-methoxy-4-hydroxyphenylethyleneglycol, the serum concentration of cortisol after the administration of flumazenil.Conclusions:Flumazenil did not result in a significant acute stress reaction in midazolam-sedated patients, but it increased myocardial oxygen consumption by enhancing sympathetic nervous activity or antagonizing cardiovascular depression induced by midazolam.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:Glutathione (GSH) is a potent endogenous antioxidant that serves as one of the body's most important defenses against oxygen metabolites. Plasma levels of GSH are maintained primarily by a balance between secretion from the liver and degradation in the kidney. The ability to maintain and enhance tissue GSH may be of particular importance in controlling cytokine production in response to a stimulus like injury. The interaction after severe trauma between GSH and cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-6, are not known.The purpose of the study was to investigate the levels of plasma GSH and cytokines TNF-α and IL-6 in adult patients admitted to the intensive care unit of our level I trauma center who were treated with recombinant human growth hormone (rhGH) for ≥7 days.Design:Prospective, randomized, controlled trial.Setting:Trauma intensive care unit.Patients:Twenty-eight patients with multiple injuries and 14 normal postabsorptive controls.Interventions:From 48-60 hrs after injury, when resuscitation was complete, a stable hemodynamic status was achieved and the patients were receiving maintenance fluid without nitrogen or calories, a blood sample was drawn for basal, plasma GSH, TNF-α, and IL-6 measurement. Intravenous feeding was then started and continued for 7 days. The patients were randomized to receive or not to receive daily intramuscular doses of recombinant human growth hormone (0.15 mg rhGH/kg/day). Daily morning plasma was obtained for analysis of GSH, TNF-α, and IL-6 levels.Results:In the early catabolic "flow phase" of severe injury, the plasma levels of GSH were not altered but plasma TNF-α and IL-6 levels were increased significantly, compared with uninjured controls. Seven days of total parenteral nutrition alone enhanced plasma GSH levels (76%), but no change in TNF-α was observed. Supplementation with rhGH enhanced GSH (180%), and TNF (65%) with no changes in IL-6 levels. There is a significant linear relationship between plasma GSH and TNF-α levels in our rhGH-supplemented trauma patients.Conclusion:Modification of plasma GSH and TNF-α levels by adequate nutritional support with adjuvant rhGH during the postinjury period demonstrates the beneficial role of GSH in enhancing antioxidant defenses.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:To describe the clinical profile and hospital outcome of successive unselected patients with pulmonary edema hospitalized in an internal medicine department.Design:Prospective, consecutive, unsolicited patients diagnosed with pulmonary edema.Setting:An internal medicine department in a 900 tertiary care center.Patients:A total of 150 consecutive unselected patients (90 males, 60 females; median age, 75 yrs).Results:Ischemic heart disease, hypertension, various valvular lesions and diabetes mellitus were present in 85%, 70%, 53%, and 52% of patients, respectively. Acute myocardial infarction at admission was observed in 15% of patients. The most common precipitating factors associated with the development of pulmonary edema included: high blood pressure (29%), rapid atrial fibrillation (29%,) unstable angina pectoris (25%), infection (18%), and acute myocardial infarction (15%). Twenty-two patients (15%) were mechanically ventilated. Eighteen patients (12%) died while in the hospital, and the cause of death was cardiac pump failure in 82%. The median hospital stay was 10 days. Predictors for increase rate of in-hospital mortality included: diabetes (p< .05), orthopnea (p< .05), echocardiographic finding of moderate-to-severely depressed global left ventricular systolic function (p< .001), acute myocardial infarction during hospital stay (p< .001), hypotension/shock (p< .05), and the need for mechanical ventilation (p< .001).Conclusions:Most patients with pulmonary edema in the internal medicine department are elderly, having ischemic heart disease, hypertension, diabetes, and a previous history of pulmonary edema. The overall mortality is high (in-hospital, 12%) and the predictors associated with high in-hospital mortality are related to left ventricular myocardial function. The long median hospital stay (10 days) and the need for many cardiovascular drugs, impose a considerable cost in the management and health care of these patients.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objective:To determine the incidence and extent of postoperative blood volume (BV) changes in patients after elective cardiac surgery using a new method based on dilution of hydroxyethyl-starch.Design:Prospective, clinical, and laboratory investigation.Setting:University hospital intensive care unit.Patients:A total of thirty-five patients undergoing cardiac surgery requiring cardiopulmonary bypass (CPB).Interventions:Perioperative measurements of circulating BV, systemic hemodynamics, lactate, and collection of clinical data.Measurements and Main Results:Measurements were made before and 1 to 72 hrs after CPB. The majority of patients undergoing cardiac surgery showed postoperative BV deficits compared with preoperative BV despite marked positive fluid balances after CPB. At 1 hr and 5 hrs after CPB, 18% and 33% of the patients, respectively, had BV deficits in the range of 0.5 L and 1.5 L, and in 3% to 10% of the cases, postoperative BV deficits exceeded 1.5 L. Concomitantly, at 5 hrs after CPB, mean arterial pressure was maximally reduced, and heart rate and lactate levels were maximally elevated. Thereafter, BV began to normalize, and at 24 hrs after CPB, pre- and postoperative mean BV were no longer significantly different. At 48 hrs and 72 hrs, even a BV surplus of more than 1 L could be observed in 6% and 14% of the patients, respectively.Conclusions:During the first hours after CPB, a high percentage of patients had significantly reduced BV and, concomitantly, showed cardiovascular dysfunction and hyperlactemia. Because hypovolemia is associated with increases of perioperative morbidity and mortality, rapid determination of BV is warranted to guide fluid therapy and optimize treatment in patients undergoing cardiac surgery.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:To compare the 6-month mortality rate of chronically ventilated patients treated either exclusively in a traditional acute-care hospital or transferred during hospitalization to a long-term acute-care facility. To analyze the hospital cost of care and estimate the amount of uncompensated care incurred by acute-care hospitals under the Medicare prospective payment diagnostic related groups system.Design:Retrospective chart review and questionnaire.Setting:Fifty-four acute-care referral hospitals and 26 long-term acute-care institutions.Patients:A total of 432 ventilated patients selected from 3,266 patients referred but not transferred to a study long-term acute-care facility and 1,702 ventilated patients from 4,174 patients referred and then subsequently transferred to the long-term acute-care facility. Six-month outcomes were determined for the subgroup of patients ≥65 yrs old (279 and 1,340 patients, respectively). Hospital charges were available for 192 of the 279 nontransferred patients who were ≥65 yrs old and 1,332 of the 1,340 transferred patients.Interventions:None.Measurements and Main Results:The 6-month mortality rate was 67.4% for the 279 nontransferred patients and 67.2% for the 1,340 transferred patients. On multiple regression analysis, variables associated with the 6-month mortality rate included initial admitting diagnosis, age, the acute physiology score, and presence of decubitus ulcer. After controlling for these variables, there was no significant difference in 6-month mortality rate, but admission to the long-term acute-care facility was associated with a longer mean survival time. Average total hospital costs for the 192 nontransferred patients was $78,474, and estimated Medicare reimbursement was $62,472, resulting in an average of $16,002 of uncompensated care per patient. Estimated costs for the long-term acute-care facility admissions were $56,825.Conclusions:Patients undergoing prolonged ventilation have high hospital and 6-month mortality rates, and 6-month outcomes are not significantly different for those transferred to long-term acute-care facilities. These patients generate high costs, and acute-care hospitals are significantly underreimbursed by Medicare for these costs. Acute-care hospitals can reduce the amount of uncompensated care by earlier transfer of appropriate patients to a long-term acute-care facility.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objectives:An exaggerated production of proinflammatory cytokines during liver transplantation stimulates the inflammatory process within the graft, and eventually promotes liver failure. This study was conducted to evaluate factors predicting perioperative response of proinflammatory cytokines during liver transplantation.Design:Prospective, consecutive entry study of liver transplant candidates.Setting:University hospital.Patients:Thirty liver transplant recipients.Interventions:Arterial blood samples were obtained perioperatively.Measurements:Interleukin (IL)-1β, IL-6, tumor necrosis factor-α were measured by ELISA. Endotoxin was determined by a chromogenic endotoxin-specific method.Main Results:The peak concentrations of IL-1β and IL-6 in the patients with complications were significantly higher than those in the patients without complications. The peak concentration of IL-1β was significantly correlated with the level of bilirubin at admission and the intraoperative blood product requirement. The peak concentration of IL-6 was significantly correlated with the admission bilirubin and the intraoperative blood product requirement. A multivariate regression model revealed that the serum bilirubin and the intraoperative blood product requirement were the independent factors that influenced the peak concentration of IL-1β or IL-6. The severely jaundiced patients had a significantly higher plasma concentration of endotoxin at the end of the anhepatic phase. In addition, there was a tendency for these patients to have a higher postoperative peak concentration of endotoxin.Conclusions:Serum level of bilirubin may be a potent preoperative factor influencing perioperative cytokine response in patients undergoing liver transplantation. An enhanced perioperative response of endotoxin seen in severely jaundiced patients suggests the clinical implication of endotoxin removal during the anhepatic phase in liver transplant surgery.

ISSN:0090-3493    

出版商:OVID    

年代:2000

数据来源: OVID