ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To answer the following question: In difficult-to-wean patients, which of the three commonly used techniques of weaning (T-piece, synchronized intermittent mandatory ventilation, or pressure support ventilation) leads to the highest proportion of successfully weaned patients and the shortest weaning time?Data Sources:Computerized literature searches in MEDLINE (1975-1996), Cinahl (1982-1996), and Healthplan (1985-1996), exploding all Mesh headings pertaining to Mechanical Ventilation and Weaning. Searches were restricted to the English language, adults, and humans. Personal files were hand searched, and references of selected articles were reviewed.Study Selection:a)Population:Patients requiring a gradual weaning process from the ventilator (either requiring prolonged initial ventilation of >72 hrs or a failed trial of spontaneous breathing after >24 hrs of ventilation); b)Interventions:At least two of the following three modes of weaning from mechanical ventilation must have been compared: T-piece, synchronized intermittent mandatory ventilation, or pressure support ventilation; c)Outcomes:At least one of the following: weaning time (time from initiation of weaning to extubation) or successful weaning rate (successfully off the ventilator for >48 hrs); and d)Study design:Controlled trial.Data Extraction:Two reviewers independently reviewed the articles and graded them according to their methodologic rigor. Data on the success of weaning and the time to wean were summarized for each study.Data Synthesis:The search strategy identified 667 potentially relevant studies; of these, 228 had weaning as their primary focus, and of these, 48 addressed modes of ventilation during weaning. Only 16 of these 48 studies had one of the specified outcomes, and only ten of these were controlled trials. Of the ten trials, only four fulfilled all our selection criteria. The results of the trials were conflicting, and there was heterogeneity among studies that precluded meaningful pooling of the results.Conclusions:There are few trials designed to determine the most effective mode of ventilation for weaning, and more work is required in this area. From the trials reviewed, we could not identify a superior weaning technique among the three most popular modes, T-piece, pressure support ventilation, or synchronized intermittent mandatory ventilation. However, it appears that synchronized intermittent mandatory ventilation may lead to a longer duration of the weaning process than either T-piece or pressure support ventilation. Finally, the manner in which the mode of weaning is applied may have a greater effect on the likelihood of weaning than the mode itself.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To compare the characteristics of jugular venous oxygen saturation (SjvO2) and brain tissue PO2(PbtO2) as monitors for cerebral ischemia after severe head injury. SjvO2has been useful as a monitor for cerebral ischemia, but it is limited by its inability to identify regional cerebral ischemia. PbtO2may be superior to SjvO2for this purpose, because oxygenation in localized areas of the brain can be monitored.Design:SjvO2and PbtO2were successfully monitored in 58 patients with severe head injury. The changes in SjvO2and PbtO2were compared during ischemic episodes.Setting:Neurosurgical intensive care unit of a level I trauma center.Measurements and Main Results:During the monitoring period, which averaged 90 hrs/patient, there were 54 episodes during which SjvO2decreased to <50% and/or PbtO2decreased to <8 torr. Two of these episodes were caused by an infarction in the area of the PO2probe, leaving 52 episodes of global hypoxia/ischemia that were identified by one of the two monitors. The sensitivities of the two monitors for detecting ischemia, using the thresholds of 50% and 8 torr for SjvO2and PbtO2, respectively, were similar. The SjvO2catheter detected 69.7% of the episodes and the PbtO2catheter detected 63.5% of the episodes. In most of the remaining episodes, both probes reflected a decrease in oxygenation, but not to levels below the defined thresholds. The major differences in the two measures of oxygenation included the following: a) SjvO2more consistently reflected a reduction in oxygenation during hyperventilation; b) PbtO2was affected more by changes in arterial PO2; and c) during severe global ischemia, PbtO2decreased to 0 and remained at 0, whereas SjvO2initially decreased but then increased again as cerebral blood flow ceased, and the only blood in the jugular bulb was of extracerebral origin.Conclusions:The two monitors provide complimentary information, and neither monitor alone identifies all episodes of ischemia. The best strategy for using these monitors is to take advantage of the unique features of each monitor. SjvO2should be used as a monitor of global oxygenation; but PbtO2should be used as a monitor of local oxygenation, ideally with the catheter placed in an area of the brain that is vulnerable to ischemia but that may be salvageable with appropriate treatment.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To determine whether the administration of recombinant human erythropoietin (rHuEPO) to critically ill patients in the intensive care unit (ICU) would reduce the number of red blood cell (RBC) transfusions required.Design:A prospective, randomized, double-blind, placebo-controlled, multicenter trial.Setting:ICUs at three academic tertiary care medical centers.Patients:A total of 160 patients who were admitted to the ICU and met the eligibility criteria were enrolled in the study (80 into the rHuEPO group; 80 into the placebo group).Interventions:Patients were randomized to receive either rHuEPO or placebo. The study drug (300 units/kg of rHuEPO or placebo) was administered by subcutaneous injection beginning ICU day 3 and continuing daily for a total of 5 days (until ICU day 7). The subsequent dosing schedule was every other day to achieve a hematocrit (Hct) concentration of >38%. The study drug was given for a minimum of 2 wks or until ICU discharge (for subjects with ICU lengths of stay >2 wks) up to a total of 6 wks (42 days) postrandomization.Measurements and Main Results:The cumulative number of units of RBCs transfused was significantly less in the rHuEPO group than in the placebo group (p< .002, Kolmogorov-Smirnov test). The rHuEPO group was transfused with a total of 166 units of RBCs vs. 305 units of RBCs transfused in the placebo group. The final Hct concentration of the rHuEPO patients was significantly greater than the final Hct concentration of placebo patients (35.1 ± 5.6 vs. 31.6 ± 4.1;p< .01, respectively). A total of 45% of patients in the rHuEPO group received a blood transfusion between days 8 and 42 or died before study day 42 compared with 55% of patients in the placebo group (relative risk, 0.8; 95% confidence interval, 0.6, 1.1). There were no significant differences between the two groups either in mortality or in the frequency of adverse events.Conclusions:The administration of rHuEPO to critically ill patients is effective in raising their Hct concentrations and in reducing the total number of units of RBCs they require.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objectives:To study the outcomes of elderly patients in a high-dependency care unit and to evaluate the costs and benefits of a geriatric high-dependency unit (GHDU).Design:Prospective data collection and analysis.Setting:Geriatric high-dependency unit.Patients:One hundred fifty patients ≥70 yrs of age who had been admitted to the GHDU over a 10-month period were investigated during their treatment and rehabilitation.Measurement and Main Results:The patients' Acute Physiology and Chronic Health Evaluation (APACHE) II scores and Simplified Acute Physiology Scores (SAPS) were recorded. The APACHE II scores and SAPSs provided a close correlation with the patients' mortality (correlation coefficients were 0.97 and 0.92, respectively). The SAPS proved to have a better linear relationship with the elderly patients' mortality in comparison with APACHE II scores. Most of the elderly patients included in the study were suffering from multiple premorbid medical problems. Overall, the mortality rate up to 1 month after discharge from the hospital was 48%. For patients ranging in age from 70 to 84 yrs, the 1-month mortality was 39.6%; however, for patients ≥85 yrs of age, the 1-month mortality was 68.1%. The mortality ratio was 0.96 (for all patients), 0.88 (for those ages 70-84 yrs), and 1.05 (for those age 85 yrs and above). For patients with nil organ system failure, the mortality rate was 32%. For patients with one organ system failure, the mortality increased to 48%. For patients with two organ system failures, the mortality rate was 86%. Survival for patients with three or more organ system failures was unprecedented. Survivors and nonsurvivors were compared. Three poor-prognosis groups were identified: group 1, patients who had received preadmission cardiopulmonary resuscitation; group 2, patients with a recent history of malignant diseases; and group 3, patients who had been mechanically ventilated. All three groups had a significantly higher mortality than those without these factors (p< .05). Patients in the 85 yrs and above group had a significantly higher mortality rate than those in the 70- to 84-yr age group (p< .05). Patients with SAPS and APACHE II scores >20 and >30, respectively, had a poor prognosis. The geriatric outcome scoring system (GOSS) was used as the functional outcome test for the survivors. The GOSS has three components: activities of daily living, mobility status, and social condition. At 1 month after discharge, 66.7% of the survivors returned to their premorbid activities of daily living abilities, 79.5% maintained their mobility status, and 91.7% remained at the same social environment. No survivors deteriorated more than one grade in any of the three components measured by the GOSS. The severity-of-illness scores, percentage of mechanical ventilation utilization, mortality rate, length of GHDU stay, and total hospital stay were comparable with those of other intensive care units (ICUs). The cost of 1 GHDU bed-day was equivalent to 24% of 1 ICU bed-day.Conclusion:The prognostic information that we gathered from an unselected group of critically ill elderly patients is useful. The GHDU achieved treatment results similar to those achieved by an ICU and is therefore seen as an innovative way of treating critically ill elderly patients. High-dependency care for the elderly patient is worthwhile.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To explore the accuracy of a continuous transcutaneous CO2(TcCO2) monitor, used in an intermittent rather than a continuous fashion, to obtain quick (<5 mins) CO2readings.Design:Prospective study.Setting:An urban pediatric intensive care unit in a university teaching hospital.Patients:A convenience sample of pediatric patients with indwelling arterial catheters.Intervention:Transcutaneous monitoring was done simultaneous with arterial blood gas monitoring.Measurements and Main Results:There were 49 simultaneous-readings on 19 patients, age 5 days to 16 years, with 13 different diagnoses. The TcCO2was related to the PCO2by a Pearson product coefficient of 0.79 (p< .0005), with a mean difference of 1.94 (TcCO2> PCO2) and 95% confidence interval of −0.12 to 4.07. The scatterplot produces a regression line characterized by the following equation: PCO2= (TcCO2× 1.05) − 4.08.Conclusions:Further study to evaluate intermittent TcCO2as a practical clinical variable is warranted. This study should encourage refinement of the technology to be more accurate for this use.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To more clearly define the relationship between an oxygen flux test, oxygen supply dependency, and outcome in patients with sepsis, severe sepsis, or septic shock.Design:Prospective, interventional clinical trial.Setting:A teaching hospital general intensive care unit in London, UK.Patients:A total of 36 patients with sepsis, severe sepsis, or septic shock were studied during a 10-month period.Interventions:After resuscitation, patients were given an intravenous infusion of dobutamine at 10 μg/kg/min for 1 hr. Cardiac and respiratory variables were measured before the infusion and then while the infusion was in progress. Any patient who was able to increase his or her oxygen consumption by >15% was designated a responder to the test.Measurements and Main Results:Hemodynamic, oxygen transport, and lactate measurements were made at baseline and after 1 hr of the dobutamine infusion. All patients were then followed up until hospital discharge. Responders to this test had a hospital mortality of 14%, whereas nonresponders had a mortality of 91% (p< .01). The responders were characterized by being younger (p< .05), having higher Acute Physiology and Chronic Health Evaluation III scores (p< .05), and having a greater requirement for inotropic support (p< .05). After the test, the responders had significantly higher oxygen delivery (p< .01) and oxygen consumption (p< .05) than the nonresponders, as well as a significantly greater temperature increase as a result of the infusion (p< .05). The nonresponders were unable to increase either oxygen delivery or oxygen consumption to the dobutamine. This test was highly predictive of outcome (p< .0001). The identification of an increase in both oxygen delivery and oxygen consumption (oxygen supply dependency) was not associated with a poor outcome.Conclusion:A dobutamine oxygen flux test provides evidence of the intrinsic function of cells. The inability of these cells to increase oxidative metabolism during sepsis, as indicated by the dobutamine test, is associated with a high mortality.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To define the occurrence rate of acute respiratory distress syndrome (ARDS) using established criteria in a well-defined general patient population, to study the clinical course of ARDS when patients were ventilated using a "lung-protective" strategy, and to define the total costs of care.Design:A 3-yr (1993 through 1995) retrospective descriptive analysis of all patients with ARDS treated in Kuopio University Hospital.Setting:Intensive care unit in the university hospital.Patients:Fifty-nine patients fulfilled the definition of ARDS: PaO2/FIO2< 200 mm Hg (33.3 kPa) during mechanical ventilation and bilateral infiltrates on chest radiograph.Interventions:None.Measurements and Main Results:With a patient data management system, the day-by-day data of hemodynamics, ventilation, respiratory mechanics, gas exchange, and organ failures were collected during the period that PaO2/FIO2ratio was <200 mm Hg (33.3 kPa). The frequency of ARDS was 4.9 cases/100,000 inhabitants/yr. Pneumonia and sepsis were the most common causes of ARDS. Mean age was 43 ± 2 yrs. At the time of lowest PaO2/FIO2, the nonsurvivors had lower arterial and venous oxygen saturations and higher arterial lactate than survivors, whereas there were no differences between the groups in other parameters. Multiple organ dysfunction preceded the worst oxygenation in both the survivors and nonsurvivors. The intensive care mortality was 37%; hospital mortality and mortality after a minimum 8 months of follow-up was 42%. The most frequent cause of death was multiple organ failure. The effective costs of intensive care per survivor were US $73,000.Conclusions:The outcome of ARDS is unpredictable at the time of onset and also at the time of the worst oxygenation. Keeping the inspiratory pressures low (30-35 cm H2O [2.94 to 3.43 kPa]) reduces the frequency of pneumothorax, and might lower the mortality. Most patients are young, and therefore the costs per saved year of life are low.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:Severe posttraumatic lung injury is characterized by impairment of gas exchange and pulmonary densities. The influence of intermittent prone positioning on pulmonary gas exchange and parenchymal densities was investigated prospectively in patients with pulmonary injury after multiple trauma with blunt chest trauma.Setting:A six-bed trauma intensive care unit in a university hospital.Design:Prospective, descriptive study.Patients:Twenty-two consecutive patients with pulmonary injury after multiple trauma with blunt chest trauma and acute lung injury (n = 11) or severe acute respiratory distress syndrome (ARDS) (n = 11) according to the definitions of the consensus conference on ARDS.Interventions:Pulmonary densities were calculated planimetrically from computed tomographic scans of the chest before the first and after the last cycle of prone positioning. Indications for prone positioning were a) mechanical ventilation with FIO2> 0.5 at positive end-expiratory pressure > 10 cm H2O for >24 hrs; or b) pulmonary densities in two or more quadrants being constant or increasing within 48 hrs. Arterial blood gas analysis was performed every 2 hrs. Intrapulmonary right-to-left shunt (Qs/Qt) and alveolar-arterial PO2difference were calculated 2 hrs after the beginning and end of every prone and supine cycle, respectively. Patients were ventilated in the prone position for 8 hrs each day.Measurements and Main Results:Every single posture change from the supine to the prone position resulted in a significant average increase in the oxygenation index of 28 ± 8 torr (3.7 ± 1.1 kPa) (p< .0001). There was a significant improvement in oxygenation (4.3 ± 0.8 torr [0.57 ± 0.11 kPa]) with time between two consecutive measurements in the prone as well as the supine position (p< .0001). Alveolar-arterial PO2difference and Qs/Qt showed a significant decrease of 25 ± 7 torr (3.3 ± 0.9 kPa) and 1.1 ± 0.46%, respectively, for every cycle of prone positioning. Statistical analysis revealed no significant alteration of gas exchange within every prone and supine cycle. Total static lung compliance improved significantly over time (p< .001). However, ventilation of patients in the prone position demonstrated a mean decrease in compliance of 2.1 ± 0.72 mL/cm H2O. The response to prone positioning was similar in patients with ARDS and acute lung injury and revealed no significant difference. In both groups, the course of the oxygenation index and Qs/Qt over time was almost parallel. Posture changes were continued for 9.0 ± 1.1 days. The oxygenation index showed an overall increase of 129 ± 20 torr (17.2 ± 2.7 kPa) from baseline supine at the end of prone positioning (p< .0001). Pulmonary densities were reduced significantly from 31.1 ± 2.5% to 3.8 ± 0.81%, Qs/Qt was reduced from 24.9 ± 1.5% to 11.7 ± 0.32%, and FIO2was reduced from 0.43 ± 0.04 to 0.26 ± 0.02 (p< .01). Gas exchange improved in all patients, and no patient died immediately as a result of respiratory failure.Conclusion:Repeated prone positioning recruits collapsed lung tissue and improves gas exchange in trauma patients with blunt chest trauma and severe ARDS as well as in trauma patients with acute lung injury.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:To evaluate hepatic and splanchnic oxygenation during liver transplantation.Design:Prospective study.Setting:University hospital.Patients:Ten adult patients undergoing liver transplantation.Interventions:Standardized surgery and anesthesia without venovenous bypass.Measurements and Main Results:Hepatic oxygenation was assessed by analyzing oxygen tension, oxygen saturation, and lactate concentration in hepatic venous blood. Splanchnic oxygenation was assessed by analyzing oxygen tension, oxygen saturation, and lactate concentration in portal venous blood and by gastric tonometry. Before reperfusion, the grafts were flushed with 1000 mL of acetated Ringer's solution and 400 mL of portal venous blood. The effluent blood from the graft was wasted and showed a mean pH of 6.86 and a lactate concentration of 9.4 mmol/L. Five minutes after portal reperfusion, most of the grafts produced lactate. Portal-hepatic venous PCO2difference ranged from 3 to 16 torr (0.4-2.1 kPa). By the time of restoration of the infrahepatic caval flow mean 24 mins later, eight of the grafts had stopped producing lactate. Mean hepatic venous oxygen tension was 47 torr (6.3 kPa), stabilizing to 41 torr (5.5 kPa) at the end of surgery. Acidosis resolved without pharmacologic interventions. Mean gastric mucosal pH was 7.29 during the anhepatic phase and 7.40 at the end of surgery. One of the patients developed hepatic arterial thrombosis intraoperatively. Her data were analyzed separately. Later, the other patients recovered with good liver function, whereas the patient with hepatic arterial thrombosis was successfully retransplanted.Conclusions:The liver grafts received well-oxygenated portal venous blood during reperfusion, despite the low values of gastric mucosal pH immediately before reperfusion. Hepatic oxygenation became adequate soon after reperfusion. In the patient with hepatic arterial thrombosis, the recovery of hepatic oxygenation was impaired and lactic acidosis persisted.

ISSN:0090-3493    

出版商:OVID    

年代:1999

数据来源: OVID