ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo evaluate the ability of two prognostic systems to predict hospital mortality in adult intensive care patients.DesignProspective cohort study.SettingA mixed medical and surgical intensive care unit (ICU) in the United Kingdom.PatientsA total of 1,144 patients consecutively admitted to the study.InterventionsNone.Measurements and Main ResultsAcute Physiology and Chronic Health Evaluation (APACHE) II and III prognostic systems were applied to assess probabilities of hospital mortality, which were compared with the actual outcome. The overall goodness-of-fit of both models was assessed. Hospital death rates were higher than those predicted by each system. Risk estimates showed a strong positive correlation between both systems (nonsurvivors r2= 0.756, p < .0001; survivors r2= 0.787, p < .0001). Calibration of APACHE II (chi squared = 98.6, Lemeshow-Hosmer) was superior to that of APACHE III (chi squared = 129.8, Lemeshow-Hosmer). The total correct classification rate of APACHE III was greater for all decision criteria applied; the best overall total correct classification rate was 80.6% for APACHE III and 77.9% for APACHE II (both for a decision criterion of 40%). The areas under the receiver operating characteristic curves were 0.806 and 0.847 for APACHE II and III, respectively, confirming the better discrimination of APACHE III. When patients were classified by diagnostic categories, risk predictions did not fit uniformly across the spectrum of disease groups. For both models, mortality ratios were highest for trauma patients and lowest for the group with respiratory disease. APACHE II predictions for patients with gastrointestinal disease were significantly better. Risk estimates for surgical admissions were superior with APACHE II (MR = 1.27) compared with APACHE III (MR = 1.56), but were similar for medical patients (1.22 vs. 1.28 for APACHE II and III, respectively). Bias induced by factors reflecting the clinical practice in an individual ICU (e.g., admission criteria, treatment before admission) may have considerable impact on risk estimates. The identification of such factors appears to be a prerequisite for the meaningful interpretation of observed and predicted death rates on the individual ICU level.ConclusionsBoth predictive models demonstrated a similar degree of overall goodness-of-fit. APACHE II showed better calibration, but discrimination was better with APACHE III. Hospital mortality was higher than predicted by both models, but was underestimated to a greater degree by APACHE III. Risk estimates by both models showed considerable variation across the disease spectrum of ICU patients. Risk predictions for surgical patients and patients with gastrointestinal disease were better with APACHE II. Factors reflecting the clinical practice of an individual ICU are not accounted for by APACHE II and III. Overall, the performance of APACHE III was not superior to that of its predecessor for a cohort of United Kingdom ICU patients; for certain diagnostic categories, APACHE III performed worse than APACHE II despite an improved system of disease classification. (Crit Care Med 1997; 25:9-15)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo evaluate the influence of body position on the extent and distribution of experimental lung damage in an oleic acid canine model of acute respiratory distress syndrome, using mechanical ventilation with high tidal volumes and positive endexplratory pressure (PEEP).DesignProspective, randomized study.SettingExperimental animal laboratory.SubjectsTwelve anesthetized and paralyzed dogs.InterventionsNinety minutes after lung injury was induced by injection of oleic acid, 12 animals were randomized to be ventilated for 4 hrs, in either the supine (supine group, n = 6) or prone (prone group, n = 6) positions, using the same ventilatory pattern (FIO2or=to10 cm H2O, and a tidal volume that generated a peak transpulmonary pressure of 35 cm H2O when implemented in the supine position). Regardless of randomization to position, the tidal volumes, FIO2, and PEEP were kept constant and the pulmonary artery occlusion pressure was maintained between 4 and 6 mm Hg for the duration of the study.Measurements and Main ResultsAt the end of the protocol, the lungs were excised for gravimetric determination (wet/dry weight ratio) and histologic examination (histologic score). Changes over time in the static pressure-volume curve of the lungs (obtained in the supine position) were also used as end-point variables..05) different when measured in the supine position. At the end of the experiment, lung gravimetric data in the two experimental groups were not statistically different, suggesting a similar extent of edema. Histologic abnormalities, however, were less in the prone group than in the supine group (p < .01), due primarily to marked differences in extent and severity in the dependent regions of the lungs. Static lung compliance improved over time in the prone group (34 +/- 9 to 46 +/- 19 mL/cm H2O) (p = .02), but not in the supine group (34 +/- 6 to 36 +/- 6 mL/cm H2O).ConclusionsAfter oleic acid-induced lung injury, animals ventilated with high tidal volume and PEEP undergo less extensive histologic change in the prone position than in the supine position. The prone position alters the distribution of histologic abnormalities. (Crit Care Med 1997; 25:16-27)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo investigate the relationship between the period of mechanical ventilation before extracorporeal life support and survival in patients with respiratory failure.DesignRetrospective review.SettingSurgical intensive care unit at a university medical center.PatientsThirty-six consecutive adult patients with severe respiratory failure managed with extracorporeal life support.Interventions90%. Management protocols were followed before and during extracorporeal life support. The 36 patients were physiologically similar before extracorporeal life support was initiated: shunt of 48 +/- 17%; FIO2of 1.0 +/- 0.1; peak inspiratory pressure of 56 +/- 16 cm H2O; positive end-expiratory pressure of 14 +/- 6 cm H2O; and respiratory rate of 23 +/- 10 breaths/min. Ventilation was utilized for 1 to 17 days before extracorporeal life support. Typical lung rest settings during extracorporeal life support were FIO2of 0.40, peak inspiratory pressure of 30 cm H2O, positive end-expiratory pressure of 10 cm H2O, and respiratory rate of 6 breaths/min. Death was almost always secondary to end-stage pulmonary failure.Measurements and Main ResultsSurvival (hospital discharge) in these 36 patients was inversely associated with the number of days of preextracorporeal life support ventilation, with a 50% mortality rate predicted by logistic regression after 5 days of mechanical ventilation. The overall survival rate was 18 (50.0%) of 36 patients.ConclusionIn severe acute respiratory failure treated with lung rest and extracorporeal life support, a predicted 50% mortality rate was associated with 5 days of preextracorporeal life support mechanical ventilation. (Crit Care Med 1997; 25:28-32)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo compare the effectiveness of sedation, the time required for weaning, and the costs of prolonged sedation of critically ill mechanically ventilated patients with midazolam and propofol.DesignOpen-label, randomized, prospective, phase IV clinical trial.SettingMedical and surgical intensive care unit (ICU) in a community hospital.Patients24 hrs. A total of 108 patients were included in the study.InterventionsPatients were randomized to receive midazolam or propofol. The dose range allowed for each drug was 0.1 to 0.5 mg/kg/hr for midazolam and 1 to 6 mg/kg/hr for propofol. The lowest dose that achieved an adequate patient-ventilator synchrony was infused. All patients received 0.5 mg/kg/24 hrs of morphine chloride.Measurements and Main Results500 mg/dL were also recorded as a therapeutic failure. When the patient was ready for weaning according to defined criteria, sedation was interrupted abruptly and the time from interruption of sedation to the first T-bridge trial and to extubation was measured. Cost analysis was performed based on the cost of intensive care in our unit ($54/hr).In the midazolam group (n = 54), 15 (27.8%) patients died; 11 (20.4%) patients had therapeutic failure; and 28 (51.8%) patients were subjected to a T-bridge trial. In the propofol group (n = 54), these proportions were 11 (20.4%), 18 (33.4% [including seven due to inadequate sedation, and 11 due to hypertriglyceridemia]), and 25 (46.2%), respectively. None of these values was significantly different between the two groups.Duration of sedation was 141.7 +/- 89.4 (SD) hrs and 139.7 +/- 84.7 hrs (p = NS), and cost (US dollars) attributed to sedation was $378 +/- 342 and $1,047 +/- 794 (p = .0001) for the midazolam and propofol groups, respectively.In the midazolam group, time from discontinuation of the drug infusion to extubation was 97.9 +/- 54.6 hrs (48.9 +/- 47.2 hrs to the first disconnection, and 49.0 +/- 23.7 hrs to extubation). In the propofol group, time from discontinuation of the drug infusion to extubation was 34.8 +/- 29.4 hrs (4.0 +/- 3.9 hrs to the first disconnection, and 30.8 +/- 29.2 hrs to extubation). The difference between the two groups in the weaning time was 63.1 +/- 12.5 (SEM) hrs (p < .0001).Cost per patient in the midazolam group (including ICU therapy and sedation with midazolam) was $10,828 +/- 5,734. Cost per patient in the propofol group was $9,466 +/- 5,820, $1,362 less than in the midazolam group.ConclusionsIn our population of critically ill patients sedated with midazolam or propofol over prolonged periods, midazolam and propofol were equally effective as sedative agents. However, despite remarkable differences in the cost of sedation with these two agents, the economic profile is more favorable for propofol than for midazolam due to a shorter weaning time associated with propofol administration. (Crit Care Med 1997; 25:33-40)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID

摘要:

ObjectiveTo determine the usefulness of indices of hypoxemia in assessing patients with the adult respiratory distress syndrome (ARDS).DesignRetrospective analysis of previously published data that describe the distributions of ventilation and pulmonary blood flow in ARDS.SettingUniversity research laboratory.PatientsSixteen patients with ARDS.InterventionsThe FIO2was varied between 0.21 and 1.0 in a computer model of gas exchange, based on a 50-compartment model of ventilation/perfusion inhomogeneity plus true shunt and deadspace. The indices of hypoxemia that were calculated as a function of inspired oxygen concentration included PaO2/FIO2, arterial/alveolar ratio (PaO2/alveolar PO2), the alveolar-arterial PO2difference (P[A-a]O sub 2), respiratory index (P[A-a]O2/PaO2), and venous admixture.Measurements and Main ResultsThe PaO2/FIO2ratio in patients with moderate shunts (<30%) varied considerably with alteration in FIO2. At both extremes of FIO2, the PaO2/FIO2in these patients was substantially greater than at intermediate FIO230%) had greater PaO2/FIO2ratios at low FIO2, but the PaO2/FIO2ratios decreased to relatively stable values at FIO20.5. In all patients, PaO2/FIO2remained relatively stable at FIO2or=to0.5 and PaO2values of <or=to100 torr (<or=to13.3 kPa). Other PO2-based indices exhibited less stability as FIO2was varied. If hypoxemia resulted from true shunting, venous admixture was found to be stable at all FIO2values. However, approximately one half of patients had clinically important hypoxemia resulting from mismatching of ventilation and blood flow. In these patients, venous admixture varied substantially with change in FIO2, and the degree of variation was proportional to the fraction of cardiac output perfusing gas exchange units with ventilation/perfusion ratios of <0.1.ConclusionsAll indices of hypoxemia are affected by changes in FIO2in patients with ARDS. PaO2/FIO2or=to0.5 and PaO2values of <or=to100 torr (<or=to13.3 kPa), and is a useful estimation of the degree of gas exchange abnormality under usual clinical conditions. Venous admixture varies substantially with alteration of FIO sub 2 in patients who have clinically important ventilation/perfusion abnormalities. Under these circumstances, venous admixture is a poor indicator of the efficiency of pulmonary oxygen exchange, even if venous admixture is calculated from measured arterial and venous oxygen content values. Estimated venous admixture, based on an assumed arterial-venous oxygen content difference, is even more unreliable.(Crit Care Med 1997; 25:41-45)

ISSN:0090-3493    

出版商:OVID    

年代:1997

数据来源: OVID