Renal and respiratory failure in Scottish ICUs

The purpose of this study was to define the outcome of patients receiving both renal replacement therapy and mechanical ventilation in 16 Scottish intensive care units over a 2-year period. Patients were identified from the Scottish Intensive Care Society's database. Survivors developing end-stage renal failure were identified after examination of the Scottish Renal Registry's database. Mortality was 64.2% (392/612) for all patients receiving renal replacement therapy and mechanical ventilation. End-stage renal failure developed in 1.6% (3/188) of the survivors of acute renal failure and in 33% (4/11) of the survivors with pre-existing chronic renal failure. Mortality has not improved when compared with earlier studies. End-stage renal failure rarely develops following acute renal failure in the intensive care unit.

Evaluation of predicted and actual length of stay in 22 Scottish intensive care units using the APACHE III system. Acute Physiology and Chronic Health Evaluation

The most recent edition of the Acute Physiology and Chronic Health Evaluation provides a prediction of intensive care unit length of stay in addition to the probability of hospital mortality. Intensive care length of stay is an important determinant of intensive care costs and may be an important indicator of quality of care. Data were collected from 22 Scottish intensive care units over a 2-year period to allow comparison of actual intensive care unit length of stay with that predicted by the Acute Physiology and Chronic Health Evaluation III system. Correlation between actual and predicted stay for individual patients was poor. However, performance of the model for patients, grouped either by predicted length of stay or by intensive care unit, indicated that the model stratified patient groups appropriately while demonstrating a consistent bias. Length of stay in Scottish intensive care units was found to be consistently lower than that predicted by a model which is based on intensive care practice in the USA. Variations in severity of illness in intensive care unit populations cannot readily explain differences in intensive care unit length of stay. The availability of a model capable of predicting length of intensive care stay, based on data reflecting practice in the UK, would compliment current methods of assessing effectiveness of intensive care.

Assessment of the performance of five intensive care scoring models within a large Scottish database

OBJECTIVE

To assess and compare the performance of five severity of illness scoring systems used commonly for intensive care unit (ICU) patients in the United Kingdom. The five models analyzed were versions II and III of the Acute Physiology and Chronic Health Evaluation (APACHE) system, a version of APACHE II using United Kingdom (UK)-derived coefficients (UK APACHE II), version II of the Simplified Acute Physiology Score (SAPS), and version II of the Mortality Probability Model, computed at admission (MPM0) and after 24 hrs in the ICU (MPM24).

DESIGN

A 2-yr prospective cohort study of consecutive admissions to intensive care units.

SETTING

A total of 22 general ICUs in Scotland

PATIENTS

A total of 13,291 admissions to the study, which after prospectively agreed exclusions left a total of 10,393 patients for the analysis.

OUTCOME MEASURES

Death or survival at hospital discharge.

MEASUREMENTS AND MAIN RESULTS

All the models showed reasonable discrimination using the area under the receiver operating characteristic curve (APACHE III, 0.845; APACHE II, 0.805; UKAPACHE II, 0.809; SAPS II, 0.843; MPM0, 0.785; MPM24, 0.799). The levels of observed mortality were significantly different than that predicted by all models, using the Hosmer-Lemeshow goodness-of-fit C test (p < .001), with the results of the test being confirmed by calibration curves. When excluding patients discharged in the first 24 hrs to allow for comparisons using the same patient group, APACHE III, MPM24, and SAPS II (APACHE III, 0.795; MPM24, 0.791; SAPS II, 0.784) showed significantly better discrimination than APACHE II, UK APACHE II, and MPM0 (APACHE II, 0.763; UK APACHE II, 0.756; MPM0, 0.741). However, calibration changed little for all models with observed mortality still significantly different from that predicted by the scoring systems (p < .001). For equivalent data sets, APACHE II demonstrated superior calibration to all the models using the chi-squared value from the Hosmer-Lemeshow test for both populations (APACHE III, 366; APACHE II, 67; UKAPACHE II, 237; SAPS II, 142; MPM0, 452; MPM24, 101).

CONCLUSIONS

SAPS II demonstrated the best overall performance, but the superior calibration of APACHE II makes it the most appropriate model for comparisons of mortality rates in different ICUs. The significance of the Hosmer-Lemeshow C test in all the models suggest that new logistic regression coefficients should be generated and the systems retested before they could be used with confidence in Scottish ICUs.

Should the pre-sedation Glasgow Coma Scale value be used when calculating Acute Physiology and Chronic Health Evaluation scores for sedated patients? Scottish Intensive Care Society Audit Group

OBJECTIVE

To assess the effect on the performance of Acute Physiology and Chronic Health Evaluation (APACHE) II and APACHE III of two different approaches to scoring the Glasgow Coma Scale (GCS) in sedated patients. The first approach was to assume that the GCS score was normal, and the second was to use the GCS value recorded before the patient was sedated.

DESIGN

Prospective cohort study over 2 yrs.

SETTING

Twenty-two general adult intensive care units in Scotland.

PATIENTS

13,291 consecutive admissions to the participating intensive care units.

MEASUREMENTS AND MAIN RESULTS

After exclusion of patients according to standard, predefined criteria, the Acute Physiology and Chronic Health Evaluation II and III systems were used to calculate the probability of hospital mortality for patients included in the study. In patients whose GCS scores could not be assessed accurately during the first 24 hrs, the APACHE II and III predictions were calculated twice: first, assuming that the GCS score was normal; and second, substituting the GCS score recorded before sedation. This generated two different databases for each system, and the predictions for both were compared with the observed hospital mortality rate. The effect of the two different approaches to the GCS on the performance of both APACHE II and APACHE III was assessed using measures of discrimination (area under the receiver operating characteristic curve) and goodness of fit (calibration curves and the Hosmer-Lemeshow statistic). Analysis was undertaken for both the entire cohort and for the group of patients whose APACHE scores were altered. There was a wide variation in the number of patients who had their scores altered between participating units. There were also differences between diagnostic groups. Overall, however, 50% of the patients were sedated and 22% had their scores altered. Using the presedation GCS score increased the discrimination of both APACHE II and APACHE III. The calibration of APACHE III was also improved but that of APACHE II deteriorated. The calibration improved, however, in those patients with altered scores, suggesting that the overall deterioration is attributable to other limitations in the fit of the model to these data. Although changes had the greatest effect in patients with a neurologic or trauma diagnosis, the changes were important in most diagnostic groups.

CONCLUSIONS

The GCS is an important component of both APACHE II and APACHE III. It should be assessed directly whenever possible. When patients are sedated, using the GCS score recorded before sedation is preferable to the assumption of normality. The variations between different units and different diagnostic groups highlight the possible effects of case mix on the performance of prognostic scoring systems.

Proinflammatory mediator activity, endogenous antagonists and the systemic inflammatory response in intra-abdominal sepsis. Scottish Sepsis Intervention Group

BACKGROUND

Severe intra-abdominal sepsis continues to carry a high mortality rate. The physiological response to sepsis in this condition and its relationship with proinflammatory mediators and their endogenous antagonists require further clarification.

METHODS

Fifty-seven patients were stratified by Acute Physiology And Chronic Health Evaluation (APACHE) II score at the time of admission to an intensive care unit (group 1, score of less than 20; group 2, score of 20 or more). Serial measurements of clinical and immunological variables were made.

RESULTS

Non-survivors from group 2 had a raised acute physiology score (P = 0.01), a higher peak serum interleukin (IL) 6 concentration (P = 0.03) and a depressed level of endogenous immunoglobulin (Ig) G class antiendotoxin core antibody (P = 0.005). In group 1, although organ failure score increased progressively in non-survivors, physiology score and peak IL-6 level were similar to those in survivors, and endogenous IgG class antiendotoxin core antibody titre rose (P = 0.02). In both groups IL-1 and tumour necrosis factor alpha were detected infrequently, but their natural antagonists were present in much higher concentrations in both survivors and non-survivors. Levels of C-reactive protein were raised in both but were not significantly different between survivors and non-survivors.

CONCLUSION

During the development of organ failure and death, the pattern of proinflammatory mediators and their endogenous antagonists can vary markedly and may in part be determined by the extent of the initial physiological disturbance.

Natural cytokine antagonists and endogenous antiendotoxin core antibodies in sepsis syndrome. The Sepsis Intervention Group

OBJECTIVE

To assess the value of measuring circulating concentrations of mediators (endotoxin, tumor necrosis factor-alpha [TNF-alpha], interleukin-1 beta [IL-1 beta], and interleukin-6[IL-6]) and their endogenous antagonists (antiendotoxin core antibody [EndoCAb], interleukin-1 receptor antagonist [IL-1ra], and soluble TNF receptors [sTNF-R]) in predicting mortality and organ failure in sepsis syndrome.

DESIGN

Cohort study with a follow-up period of 30 days.

SETTING

Intensive therapy units of five tertiary referral centers in Scotland.

SUBJECTS

A total of 146 intensive therapy unit patients with sepsis syndrome underwent repeated sampling during a 10-day period following admission to an intensive therapy unit.

MAIN OUTCOME MEASURES

Circulating concentrations of mediators and antagonists were compared in survivors and nonsurvivors.

RESULTS

Median Acute Physiology and Chronic Health Evaluation II score was 23 (range, 8 to 40). Mortality at 30 days was 49%. On entry to the study, circulating endotoxin was detected in 66% of patients, TNF-alpha in 14%, and IL-1 beta in 29%. Levels did not predict mortality or organ failure. Patients with IL-6 concentrations in excess of 3000 pg/mL had an increased mortality rate (64% vs 40%, P = .02). The incidence of IgG EndoCAb depletion on entry to the study was 26% in nonsurvivors and 10% in survivors (P = .02). Initial concentrations of both type I and type II sTNF-R were significantly higher in nonsurvivors (P < .01). Initial circulating IL-1ra concentrations were not of value in predicting mortality. Cytokine antagonists were present in concentrations 30- to 100,000-fold greater than their corresponding cytokine.

CONCLUSION

The observed high circulating levels of the cytokine antagonists IL-1ra and sTNF-R and the relatively small proportion of patients developing EndoCAb depletion may contribute to the limitations of therapies that aim to augment natural defenses against endotoxin or the proinflammatory cytokines.

Effective concentration 50 for propofol with and without 67% nitrous oxide

The Effective Blood Concentration (EC) of propofol required to prevent response to surgical incision was determined in 65 ASA I or II female patients breathing either 100% oxygen or 67% N2O in oxygen. Propofol was administered via a microcomputer-controlled infusion system programmed to maintain the blood propofol concentration at predetermined target values. The blood propofol concentrations predicted by the micro-computer were validated by measurement of whole blood propofol concentration. Predicted and measured concentrations differed during infusion of propofol, but became similar after discontinuing the infusion for at least 90 s, suggesting that equilibration within the central compartment was incomplete during infusion. The response to the initial incision was observed and probit analysis used to determine the predicted blood concentration at which 50% of patients responded. The predicted EC50 for propofol/N2O/O2 and propofol/O2 was 4.5 micrograms ml-1 and 6.0 micrograms ml-1 respectively, and the measured EC50 propofol/N2O/O2 and propofol/O2 was 5.36 micrograms ml-1 and 8.1 micrograms ml-1, 67% nitrous oxide in oxygen reducing the predicted EC50 by 25% and the measured EC50 of propofol by 33%. The predicted EC may be more representative of the equilibrated concentration in the central compartment and thus reflective of tissue propofol concentrations.

Comparison of two methods for predicting difficult intubation

Two methods of predicting difficult laryngoscopy were compared prospectively. Mallampati class and Wilson risk-sum were determined before operation and laryngeal view graded in 675 patients. Both tests identified five of 12 difficult laryngoscopies; twice as many patients were predicted to be difficult by Mallampati classification than by Wilson risk-sum. Inter-observer variation was minimal using Wilson risk-sum, but considerable for Mallampati classification. We prefer the Wilson risk-sum for assessment of the airway, while noting that both tests have poor sensitivities.

Assessment of the analgesic efficacy of nefopam hydrochloride after upper abdominal surgery: a study using patient controlled analgesia

A randomized, double-blind, placebo-controlled study was performed to assess the analgesic efficacy of intramuscular nefopam hydrochloride after upper abdominal surgery. Patients received either 20 mg nefopam (n = 23) or matching placebo (n = 26), 90 min before surgery, immediately after surgery, and 6, 12 and 18 h after the end of surgery. The 24-h morphine requirements were measured using a patient-controlled analgesia system delivering on-demand intravenous bolus doses of morphine. Pain was assessed using visual analogue scales. Patients receiving nefopam had a mean (+/- s.e.m.) cumulative morphine consumption of 4.1 +/- 0.8 mg in the first hour, compared with 8.5 +/- 0.8 mg in the control group (P less than 0.01). After 24 h the consumptions were 44.1 +/- 7.2 mg and 62.5 +/- 6.9 mg respectively (P less than 0.05). The pain scores in both groups were similar. This study confirms that nefopam hydrochloride has significant analgesic effects and would be a useful supplement to morphine in the management of postoperative pain.

Postoperative pain and pulmonary complications: comparison of three analgesic regimens

In a prospective study, patients undergoing cholecystectomy were randomly allocated to receive (a) intermittent intramuscular morphine (n = 25), (b) continuous intravenous morphine infusion (n = 25) or (c) epidural bupivacaine (n = 25) for postoperative pain relief. Morphine by intravenous infusion provided comparable pain relief to intermittent intramuscular morphine; there was no significant difference in the incidence of postoperative pulmonary complications. Patients receiving epidural bupivacaine for 12 h had better analgesia than patients receiving morphine (P less than 0.001). Arterial oxygen tensions were also significantly higher in the epidural group for the first three postoperative days (P less than 0.05). Epidural analgesia was associated with a significant reduction in the incidence of pulmonary complications (P less than 0.01) and chest infection (P less than 0.05).