Severity and Outcome of ARDS: The Present Place of Extracorporeal Lung Assist (ECLA)

Within the last decade extracorporeal lung assist has been recommended for the treatment of acute respiratory distress syndrome. However, this recommandation was challenged by several recent clinical studies and reviews. The goal of our analysis was therefore to investigate data on outcome and severity of gas exchange disturbance published from patients treated with ECLA. These data were compared to a historical control group consisting of ARDS patients treated conventionally. Computerized (MEDLINE 1967-95) literature search using the keywords ARDS, ECLA, ECMO, ECCO2R and HUMAN was performed. Only clinical studies published as full papers reporting data on both, patients mortality and oxygenation index (PaO2/FiO2) were included. Overall mean mortality reported was 53±22% in 17 studies (419 patients), with no apparent trend towards a higher survival within the last decade with a mean PaO2/FIO2 (14 papers; 61±17 mmHg). However, mean mortality rates of ARDS patients requiring ECLA was 52.3% and 44.9% if patients undergoing ECMO were excluded (3 papers). Therefore the mortality of these patients with severe lung injury was in the range of patients treated conventionally. Patient outcome observed in our analysis is in accordance with the mortality rates from the European ECLA centres published recently (49% in 1993). Therefore, we conclude that the mean mortality rate of patients suffering from severe ARDS treated with ECLA is in the 50% range and does not differ significantly from those of patients treated conventionally, despite significantly poorer pulmonary function.

Perioperative kinetics of heat shock protein 60 in serum during orthotopic liver transplantation

INTRODUCTION

Heat shock proteins (HSP) play essential roles in the synthesis, transport, and folding of proteins. During ischemia/reperfusion (I/R) injury to orthotopic liver transplants (OLT), disassembly of oligomeric complexes and unfolding of proteins are likely to occur, producing a major burden on HSP to prevent and/or reverse these events. To date, all studies have evaluated HSP expression in tissues after an I/R injury. No data are available on HSP serum levels during I/R injury in liver graft recipients.

PATIENTS AND METHODS

We evaluated the intraoperative and perioperative kinetics of HSP60 in the serum of 25 liver graft recipients.

RESULTS

We observed a significant increase in serum levels of HSP60 at 4 hours compared with 30 minutes after reperfusion of the graft (P = .028). The perioperative HSP60 kinetics in serum neither correlated with the cold ischemia time nor the indocyanin green clearance. The type of preservation solution had no effect on serum HSP60 levels.

CONCLUSION

This first study provides evidence for increased serum levels of HSP60 after reperfusion in OLT. The perioperative kinetics of HSP60 in serum may result from suppressed protein synthesis caused by a reduced energy charge of hepatocytes during early reperfusion, impaired transcription, and/or corticosteroid treatment. Further studies are needed to clarify the role of HSP60 under clinical conditions including immunosuppressive medications in human OLT.

Perioperative cytokines during orthotopic liver transplantation without venovenous bypass

Since most of studies investigating cytokine levels during human orthotopic liver transplantation used venovenous bypass (VVB), it may be difficult to distinguish between the increase in proinflammatory mediators induced by VVB, by ischemia-reperfusion injury or by splanchnic venous congestion in the anhepatic phase. The goal of this investigation was to assess the levels of interleukin-6 (IL-6) and soluble interleukin-2 receptors (sIL-2r) during OLT procedures routinely performed without VVB.

PATIENTS AND METHODS

Twenty-one consecutive patients underwent OLT with cross clamping of the inferior caval vein without VVB. Soluble IL-2r concentrations were measured by means of luminescence enzyme immunometric assay and IL-6 by means of a sequential immunometric assay. Time points (TP) of sampling were before induction of anesthesia (TP1), after cross-clamping of the inferior vena cava (TP2), 15 minutes after reperfusion (TP3), and 24 hours after the transplant procedure (TP4).

RESULTS

Soluble IL-2r increased significantly 24 hours after transplantation (P =.02) compared to TP1, TP2, and TP3. IL-6 increased significantly during the anhepatic period (TP2 vs TP1, P =.003) and again in the reperfusion period (TP2 vs TP3, P =.002). Twenty-four hours after surgery IL-6 declined significantly (TP3 vs TP4, P =.001), but remained significantly higher (P = 0.04) compared to TP1. Furthermore, we examined the relative changes (DeltaTP %) in perioperative levels of cytokines compared with those previously published in studies using VVB. We observed higher values of DeltaTP % of IL-6 in TP2 and TP4 among our group of patient without VVB. The data on sIL-2r were similar, suggesting no major effects of the operative technique on sIL-2r levels.

CONCLUSION

The two interleukins showed different perioperative trends. Our data suggest that cross clamping contributes more to cell activation, namely, increased release of IL-6 in the anhepatic phase than the use of VVB. However, no major differences were observed during the reperfusion period. The extent of clinical effect on graft function of higher IL-6 levels in the anhepatic period among recipients not supported with VVB remains to be clarified.

Changes in lung parenchyma after acute respiratory distress syndrome (ARDS): assessment with high-resolution computed tomography

The aim of this study was to evaluate the appearance, extent, and distribution of parenchymal changes in the lung after acute respiratory distress syndrome (ARDS) as a function of disease severity and therapeutic procedures. High-resolution computed tomography (HRCT), clinical examination, and lung function tests were performed in 15 patients, 6-10 months after ARDS. The appearance and extent of parenchymal changes were compared with the severity of ARDS, as well as with clinical and therapeutic data. Lung parenchymal changes resembling those found in the presence of pulmonary fibrosis were observed in 13 of 15 patients (87%). The changes were significantly more frequent and more pronounced in the ventral than in the dorsal portions of the lung ( p<0.01). A significant correlation was observed between the extent of lung alterations and the severity of ARDS ( p<0.01), and the duration in which patients had received mechanical ventilation either with a peak inspiratory pressure greater than 30 mmHg ( p<0.05), or with more than 70% oxygen ( p<0.01). Acute respiratory distress syndrome frequently is followed by fibrotic changes in lung parenchyma. The predominantly ventral distribution of these changes indicates that they may be caused by the ventilation regimen and the oxygen therapy rather than by the ARDS.

Evaluation of the logistic organ dysfunction system for the assessment of organ dysfunction and mortality in critically ill patients

OBJECTIVES

To evaluate the performance of the logistic organ dysfunction (LOD) system for the assessment of morbidity and mortality in multiple organ dysfunction/failure (MOD/F) in an independent database and to evaluate the use of sequential LOD measurements for the prediction of outcome.

DESIGN AND SETTING

Prospective, multicentric cohort study in 13 adult medical, surgical, and mixed intensive care units (ICUs) in Austria.

PATIENTS

A total of 2,893 consecutive admissions to the ICUs.

MEASUREMENTS AND MAIN RESULTS

Patient vital status at ICU and hospital discharge was recorded. Univariate analysis showed that the LOD was able to distinguish between survivors and nonsurvivors (2 vs. 6 median score). Within organ systems, higher levels of the severity of organ dysfunction were consistently associated with higher mortality. For the prediction of hospital mortality, the original prognostic LOD model did not perform well in our patients, as indicated by the goodness-of-fit C statistic. Using multiple logistic regression we developed a prognostic model with a satisfactory fit in our patients. The integration of further measurements during the ICU stay increased discrimination but not calibration.

CONCLUSIONS

The LOD system is well correlated well with the numbers and levels of organ dysfunctions and discriminates well between survivors and nonsurvivors. It can thus be used to quantify the baseline severity of organ dysfunction. Moreover, after customization of the predictive equation the LOD predicted hospital mortality in our patients with high precision. It thus provides a combined measure of morbidity and mortality for critically ill patients with MOD/F.

Effect of pre-emptive hydromorphone administration on postoperative pain relief--a randomized controlled trial

BACKGROUND AND AIM OF STUDY

Pre-emptive analgesia represents a treatment strategy which tries to prevent the development of pain by inhibiting central reactions to peripheral sensory stimuli. In a prospective randomized double-blind placebo-controlled study, the effect of oral premedication with 4 mg of a slow-release hydromorphone preparation on postoperative piritramide consumption and subjective pain perception is being evaluated.

PATIENTS AND METHODS

96 women undergoing hysterectomy were randomly assigned to four study groups. Patients from groups 1 and 2 received hydromorphone and placebo respectively two hours before surgery, while those from groups 3 and 4 were given the same substances one hour after the end of the operation. Postoperative pain relief was provided by a patient-controlled infusion pump with piritramide. The intensity of postoperative pain as perceived by the patients was quantified on a visual analogue scale. Piritramide consumption and pain scores were recorded at 1 and 24 hours after surgery. Approval of the local Ethics Committee had been obtained beforehand as well as written informed consent from the patients.

RESULTS

No significant differences in piritramide consumption were observed in between the four study groups. Visual analogue scale (VAS) ratings at 1 and 24 hours after surgery did not show any significant differences either--irrespective of whether the patients had received hydromorphone or placebo preoperatively or postoperatively.

CONCLUSION

In our study, oral administration of 4 mg of slow-release hydromorphone did not show any greater pre-emptive analgesic effect than placebo.

Intrathoracic fluid volumes and pulmonary function during orthotopic liver transplantation

BACKGROUND

Impaired pulmonary function is a frequent finding in patients undergoing orthotopic liver transplantation (OLT). Experimental data suggest an essential contribution of splanchnic ischemia and reperfusion as a result of intraoperative volume shifts, i.e., the accumulation of extravascular lung water (EVLW). Increases of intrathoracic blood volume (ITBV) and pulmonary blood volume (PBV) might additionally influence pulmonary capillary fluid filtration. The main objective of this study was to determine the intrathoracic volume changes during OLT and to test whether there were any relationships between intra- and extravascular volume shifts and pulmonary function, as determined by the calculation of venous admixture (QS/QT) and alveolar-arterial oxygen gradient (AaDO2).

METHODS

Twenty-five patients undergoing OLT were studied. Using the transpulmonary double indicator dilution method, ITBV, PBV, and EVLW were determined from the mean transit times and exponential decay times of the indocyanine green and the thermal indicator curves recorded simultaneously with a fiberoptic catheter in the descending aorta. Recordings were made after induction of anesthesia, at the end of the anhepatic stage, immediately after reperfusion, and 1 and 4 h postoperatively.

RESULTS

Significant increases in QS/QT related to changes of ITBV were observed after reperfusion. Only a minor impact on AaDO2 was perceived. EVLW remained constant during the study period.

CONCLUSIONS

Postreperfusion increases of ITBV influence pulmonary function, as demonstrated by the increase in QS/QT. However, they need not be associated with greater EVLW levels, and impact on oxygenation is less severe than assumed. Hence, sufficient mechanisms protecting oxygenation and stalling increased EVLW seem to be present during uncomplicated human OLT.

Effects of positive end-expiratory pressure on hemodynamics and indocyanine green kinetics in patients after orthotopic liver transplantation

OBJECTIVE

To determine the impact of positive end-expiratory pressure (PEEP) ventilation on hemodynamics and a clinical test for assessment of dynamic liver performance in patients undergoing orthotopic liver transplantation (OLT).

DESIGN

Prospective, descriptive patient study.

SETTING

University hospital intensive care unit.

PATIENTS

A total of 25 patients after OLT.

INTERVENTIONS

All patients were intubated and mechanically ventilated with biphasic positive airway pressure. The effects of three different randomly chosen levels of PEEP (0 cm H2O, 5 cm H2O, and 10 cm H2O) were studied in the immediate postoperative period.

MEASUREMENTS AND MAIN RESULTS

Systemic hemodynamics, arterial and venous blood gas analyses, and plasma disappearance rate of indocyanine green (ICG(PDR)), using the transpulmonary indicator dilution technique, were obtained simultaneously. For data evaluation, patients were grouped retrospectively according to their hemodynamic response to PEEP (Group A and Group B). In Group A (n = 13), PEEP did not alter cardiac index. In Group B (n = 11), PEEP levels of 5 cm H2O and 10 cm H2O significantly reduced cardiac index and oxygen delivery. ICG(PDR) remained statistically unchanged in both groups.

CONCLUSIONS

Short-term pressure-controlled ventilation with PEEP levels of up to 10 cm H2O does not exert detrimental effects on systemic hemodynamics in OLT patients and does not interfere with ICG(PDR). However, it remains to be determined whether these findings could be confirmed under the application of higher PEEP levels over a longer period of time and whether they could be of clinical relevance for the use of indocyanine green as a dynamic liver function test.

Impact of acute renal failure on antioxidant status in multiple organ failure

BACKGROUND

Acute renal failure (ARF) can be triggered or aggravated by reactive oxygen species (ROS) but established ARF per se might also affect the antioxidant defence mechanisms of the organism. We evaluated a broad pattern of antioxidants in critically ill patients with multiple organ failure with (MOF-ARF) and without acute renal failure (MOF) to identify any potential involvement of renal dysfunction in the depletion of the antioxidant system.

METHODS

Observational study; 13 patients with MOF were investigated (9 with and 4 without ARF), and 17 healthy subjects served as controls. Blood samples were drawn after establishment of MOF. Plasma levels of ascorbate, alpha-tocopherol, retinol, beta-carotene, selenium and lipid peroxidation products (MDA) were determined and the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione-peroxidase (GSH-PX) in erythrocytes were measured. In addition, ROS production (superoxide anion and hydrogen peroxide) in activated neutrophils was assessed.

RESULTS

Plasma levels of ascorbate, beta-carotene and selenium were reduced in both patient groups, when compared to controls. Decrease in selenium was more pronounced in the MOF-ARF group. MDA levels were increased in both groups, again being more pronounced in MOF-ARF patients compared to MOF patients. Hydrogen peroxide production by neutrophils from both patient groups was lower than from controls.

CONCLUSION

A depression of the antioxidative system is present in critically ill patients with MOF. In patients with associated ARF this was even more pronounced and plasma MDA levels were higher, suggesting an additional effect on the antioxidative potential in the presence of renal dysfunction and/or renal replacement therapy.

Evaluation of an interdisciplinary data set for national intensive care unit assessment

OBJECTIVES

To evaluate the ability of an interdisciplinary data set (recently defined by the Austrian Working Group for the Standardization of a Documentation System for Intensive Care [ASDI]) to assess intensive care units (ICUs) by means of the Simplified Acute Physiology Score II (SAPS II) for the severity of illness and the simplified Therapeutic Intervention Scoring System (TISS-28) for the level of provided care.

DESIGN

A prospective, multicentric study.

SETTING

Nine adult medical, surgical, and mixed ICUs in Austria.

PATIENTS

A total of 1234 patients consecutively admitted to the ICUs.

INTERVENTIONS

Collection of data for the ASDI data set.

MEASUREMENTS AND MAIN RESULTS

The overall mean SAPS II score was 33.1+/-2.1 points. SAPS II overestimated hospital mortality by predicting mortality of 22.2%+/-2.9%, whereas observed mortality was only 16.8%+/-2.2%. The Hosmer-Lemeshow goodness-of-fit test for SAPS II scores showed lacking uniformity of fit (H = 53.78, 8 degrees of freedom; p < .0001). TISS-28 scores were recorded on 8616 days (30.6+/-1.5 points). TISS-28 scores were higher in nonsurvivors than in survivors (30.4+/-0.9 vs. 25.7+/-0.4, respectively; p < .05). No significant correlation between mean TISS-28 per patient per unit on the day of admission and mean predicted hospital mortality (r2 = .23; p < .54) or standardized mortality ratio per unit (r2 = -.22; p < .56) was found.

CONCLUSIONS

Implementation of an interdisciplinary data set for ICUs provided data with which to evaluate performance in terms of severity of illness and provided care. The SAPS II did not accurately predict outcomes in Austrian ICUs and must, therefore, be customized for this population. A combination of indicators for both severity of illness and amount of provided care is necessary to evaluate ICU performance. Further data acquisition is needed to customize the SAPS II and to validate the TISS-28.

[Difference between gastric mucosal pCO2 and arterio-intramucosal pCO2 during orthotopic liver transplantation]

Tonometry is a clinically accepted method to monitor blood flow of the splanchnic region, which is of particular interest in orthotopic liver transplantation (OLT). We investigated the hemodynamic changes and the tonometrically registered perioperative course of the difference between gastric mucosal pCO2 (prCO2) and arterial mucosal CO2 (CO2 gap) in 23 patients undergoing OLT without veno-venous bypass. Gastric mucosal pH (pHi) was additionally calculated. Despite significant changes in systemic hemodynamics during the anhepatic stage and after reperfusion and a significant drop in pHi during anhepacy, the difference between prCO2 and CO2 was constant. These contrasting findings of tonometry, i.e. solely a drop in pHi is, in our opinion, a consequence of the poor metabolic capacity of the liver in the perioperative OLT period, which influenced the calculation of the pHi with the Henderson-Hasselbalch equation. We conclude that, due to methodical problems, calculated pHi is not a reliable indicator of splanchnic blood flow and oxygenation during OLT. We therefore suggest that the prCO2 and the CO2 gap be used to monitor the splanchnic region. These parameters, obtained perioperatively, do not indicate a further reduction in splanchnic oxygenation despite profound changes in systemic hemodynamics during OLT without veno-venous bypass.

The use of the antioxidant tirilazad mesylate in human liver transplantation: is there a therapeutic benefit?

OBJECTIVES

To test the hypothesis whether in patients undergoing liver transplantation the antioxidant tirilazad mesylate can reduce hepatic ischaemia-reperfusion injury and improve postoperative outcome.

DESIGN

Prospective, randomised, placebo controlled trial.

SETTING

University hospital.

PATIENTS

20 patients were randomised to receive either tirilazad mesylate or placebo (saline).

INTERVENTIONS

Patients in the tirilazad group (n = 10) received four intravenous infusions of tirilazad at 6-h intervals (men 3 mg/kg, women 3.75 mg/kg) after the induction of anaesthesia. The other patients (n = 10) served as controls.

MEASUREMENTS AND RESULTS

Plasma levels of malonaldehyde (MDA) were determined after the induction of anaesthesia prior to the infusion of tirilazad (baseline), during the anhepatic period, and 5 min and 24 h after reperfusion. Postoperatively, alanine aminotransferase, aspartate aminotransferase, prothrombin time, and serum cholinesterase were determined daily for 1 week. Compared to baseline, plasma MDA levels did not significantly change during the anhepatic period and after reperfusion and they did not differ between groups. Postoperative liver enzymes and prothrombin time did not differ between groups, but on the first (p = 0.03) and second (p = 0.01) postoperative day cholinesterase levels were significantly higher in tirilazad-treated patients than in control patients. For neither length of stay in the intensive care unit nor hospital stay were any differences observed between groups.

CONCLUSIONS

In patients undergoing liver transplantation, tirilazad does not improve overall outcome. Whether the higher cholinesterase levels on the first 2 postoperative days in tirilazad treated patients indicates an earlier recovery of liver function remains to be tested.

Splanchnic circulation is maintained during passive hyperventilation in orthotopic liver recipients

BACKGROUND

Mechanical hyperventilation is an established treatment to reduce brain edema and intracranial pressure in patients with encephalopathia caused by acute liver failure. Hyperventilation and ensuing hypocarbia may also affect central and systemic circulation and thereby influence graft performance in patients following orthotopic liver transplantation (OLT).

METHODS

We measured the effects of normocapnia and hypocapnia on systemic hemodynamics, gastric tonometry, as a marker of splanchnic oxygenation, and the indocyanine green kinetic, as a global marker of graft function, in humans post OLT.

RESULTS

Hyperventilation was performed to a PaCO2 of 4.2 +/- 0.4 kPa (31 +/- 3.4 mm Hg) for about 1 h in 14 liver transplant recipients. Systemic hemodynamics as well as indices of splanchnic oxygenation and indocyanine green kinetics remained statistically unchanged.

CONCLUSION

We did not observe any statistically significant circulatory effects or changes in indocyanine green kinetics in liver transplant recipients in the immediate OLT postoperative period caused by short-term mechanical hyperventilation.

Bilateral lung transplantation via two sequential anterolateral thoracotomies

OBJECTIVE

Bilateral anterior trans-sternal thoracotomy (clam shell incision) is the standard approach used for bilateral sequential lung transplantation (BLTX). The morbidity of this large incision can be considerable. Two separate sequential anterolateral thoractomies represent a less invasive approach.

METHODS

The value of this approach was investigated in a prospective series of 22 consecutive patients who received BLTX between June 1997 and July 1998. Their underlying diseases were COPD (n = 16), cystic fibrosis (n = 4) and other (n = 2). All patients underwent BLTX through two anterolateral thoracotomies, without the use of cardiopulmonary bypass. The anterior mediastinum and the sternum with all the surrounding tissue were left completely intact. Twenty-one patients underwent spirometrical examination during the postoperative in-hospital stay. Follow-up is 7+/-4 months (range: 3 to 15).

RESULTS

The only intraoperative complication was severe reperfusion edema of the first transplanted lung seen in one patient at the end of the operation, which required pneumonectomy during the same session. All other operations were uneventful. The difference between the cold ischemic time of the first and second transplanted lung was 83+/-17 min. Median intubation duration, ICU- and in-hospital-stay were 1.5, 5 and 20 days, respectively (ranges: 1 to 96, 2 to 96 and 15 to 96, respectively). One major perioperative complication occurred and was due to gross donor/recipient size mismatch: the patient required lobectomy of the consolidated right upper lobe 11 days after transplantation. In 19 patients (86.4%), this less extensive incision allowed early postoperative mobilization, which resulted in good ventilatory performance, with VC of 53+/-15 and FEV1 of 60+/-20% of the predicted, respectively, at the first spirometry, 3 weeks after the operation. Three months survival was 100%.

CONCLUSION

The bilateral sequential anterolateral thoracotomy represents a safe and minimal invasive approach for BLTX compared with the clam shell incision. It minimizes the operative trauma, improves postoperative functional recovery and prevents the potential spread of unilateral complications to the other pleural cavity.

[Knowledge-based diagnosis and therapeutic recommendations with fuzzy-set theory methods in patients with acute lung failure (ARDS)]

OBJECTIVE

Since the treatment of patients with severe ARDS using the extracorporal lung assist (ECLA) methods remains a cost intensive and speculative procedure, a knowledge based computer system should be created and evaluated in order to support clinical decisions.

METHODS

The model was based on the fuzzy set theory and therefore able to give decisions between yes and no, that means that a criterion could also be fulfilled to 35% or 80% for example. The development of this computer program consists of two steps: first, the entry criteria for the ECLA therapy were established within a framework of an international evaluation of clinical data from 3 centres (Berlin, Marburg, Vienna). Here, inherent vagueness, uncertainty of the occurrence and limited availability of medical data are to be considered to establish a useful tool. Secondly, this was done by grouping and weighting of parameters by the system and the status of each patient or patient group was assigned by the percentage of fulfillment of the criterion.

RESULTS

By using a mixed sample of patients from these three centres, the fulfillment of entry criteria according either to definitions of Berlin or to definition of Marburg was different (68% versus 36%). Other differences (36% vs. 22% and 68% vs. 60%) were found between the fuzzy based score and the crisp score which represents the usually performed method.

CONCLUSIONS

This now preevaluated minimal data set to describe severe ARDS patients based on the fuzzy set theory may be useful to evaluate patients for ECLA therapy or for another controlled ARDS-therapy.

Antioxidant status in patients with acute respiratory distress syndrome

OBJECTIVES

Reactive oxygen species (ROS) have been implicated in the pathophysiology of ARDS. We investigated the pattern of antioxidants in plasma and ROS production by neutrophils in patients with ARDS over 6 days.

DESIGN

Observational study. Blood samples were taken when the diagnosis was made (D0) and after 3 (D3) and 6 days (D6) during therapy.

SETTING

Intensive care units at a University Hospital.

PATIENTS

Eight patients with ARDS were investigated, 17 healthy volunteers served as controls.

MEASUREMENTS AND RESULTS

Plasma levels of ascorbate, alpha-tocopherol, retinol, beta-carotene, selenium and lipid peroxidation products (MDA) were determined and the activities of the antioxidative enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione-peroxidase (GSH-PX) in erythrocytes were measured. In addition, ROS production (superoxide anion and hydrogen peroxide) in activated neutrophils was assessed. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium were reduced from the onset of illness. MDA plasma levels were increased throughout the illness. ROS generation from neutrophils was normal on D0 and decreased to D6 in ARDS patients.

CONCLUSION

The antioxidative system is severely compromised in patients with ARDS. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium are decreased. Elevated MDA levels provide further evidence of massive oxidative stress. The routine replacement of micronutrients according to recommended daily allowances was inadequate to compensate for the increased requirements.

Prognostic performance and customization of the SAPS II: results of a multicenter Austrian study. Simplified Acute Physiology Score

OBJECTIVES

To evaluate the prognostic performance of the original Simplified Acute Physiology Score (SAPS) II in Austrian intensive care patients and to evaluate the impact of customization.

DESIGN

Analysis of the database of a multicenter study.

SETTING

Nine adult medical, surgical, and mixed intensive care units (ICUs) in Austria.

PATIENTS

A total of 1733 patients consecutively admitted to the ICUs.

MEASUREMENTS AND RESULTS

The database included admission data, SAPS II, length of stay, and hospital mortality. The Hosmer-Lemeshow goodness-of-fit test for the SAPS II showed a lack of uniformity of fit (H = 89.1, 10 df, p < 0.0001; C = 91.8, 10 df, p < 0.0001). Subgroup analysis showed good performance in patients with cardiovascular (medical and surgical) diseases as the primary reasons for admission. A new predictive equation was derived by means of the logistic regression. Goodness-of-fit was excellent for the customized model (SAPS IIAM) (H = 11.2, 9 df, p = 0.33, C = 11.6, 9 df, p = 0.24). The mean standardized mortality ratio (SMR) changed from 0.81 +/- 0.26 to 0.93 +/- 0.29 with customization.

CONCLUSIONS

SAPS II was not well calibrated when applied to all patients. However, it performed well for patients with cardiovascular diseases as the primary reason for admission and may thus be applied to these patients. Standardized mortality ratios that are calculated from scoring systems without known calibration must be viewed with skepticism.

Performance of proportional and continuous nitric oxide delivery systems during pressure- and volume-controlled ventilation

We have evaluated the effect of delivering nitric oxide using a continuous flow system (CFS) or two commercially available proportional gas injection systems (PGIS), Nodomo (Dräger, Lübeck, Germany) and Pulmonox-Mini (Messer Griesheim Austria, Gumpoldskirchen, Austria) on measured and simulated concentrations of nitric oxide. Nitric oxide concentration was measured in a bench test at five sites in the inspiratory breathing system during volume- or pressure-controlled ventilation and mathematically simulated using a mixing chamber model. For a target concentration of 10 parts per million (ppm) at the "Y" piece, simulated nitric oxide concentrations were 1.9-139 ppm for CFS, 0.3-22 ppm for the Nodomo and 0.0-31 ppm for the Pulmonox-Mini near the nitric oxide administration site. However, peak concentrations decreased rapidly along the inspiratory system. Measured and simulated variations depended on the nitric oxide delivery system, site of measurement and tidal volume. Measured variations were four times smaller in the Nodomo than in the Pulmonox-Mini and CFS. As inappropriate mixing may occur even with PGIS, nitric oxide should probably not be administered near the "Y" piece.

Measurement of right ventricular performance during apnea in patients with acute lung injury

BACKGROUND

Mechanical ventilation resulted in increased, decreased or unchanged end-diastolic volumes together with either profoundly decreased or unchanged right ventricular ejection fraction (RVEF). The goal of our study was, therefore, to evaluate the effects of positive end-expiratory pressure on measurements of RVEF performed during apneic periods with different levels of positive end-expiratory pressure.

METHODS

Fifteen consecutive patients suffering from acute lung injury after major surgery or trauma were included. Measurements were performed during 15 seconds of apnea at airway pressure levels of 0 (baseline), 10, 20, and 30 cm H2O. Cardiac output and RVEF were determined using the thermodilution technique.

RESULTS

Lung inflation to an airway pressure of 30 cm H2O caused a 22 +/- 14% decrease of cardiac output resulting from a 20 +/- 14% decrease of stroke volume index. The decrease of stroke volume index was induced by a 17 +/- 11% decrease of right ventricular end-diastolic volume index, while RVEF remained virtually unchanged (0.49 +/- 0.10 vs. 0.47 +/- 0.12 at 0 and 30 cm H2O, respectively). Relative changes of cardiac output were closely correlated with changes of right ventricular end-diastolic volume index (p < 0.05, r2 = 0.78).

CONCLUSIONS

Right ventricular systolic function was well maintained despite substantially decreased end-diastolic volumes. In our study, during apneic conditions, higher levels of positive end-expiratory pressure did not worsen RVEF in patients with acute lung injury. The proposed technique of apneic lung inflation may serve as an alternative approach to obtain comparable measurements of RV function in patients with acute lung injury.

Effects of pentoxifylline on hemodynamics and oxygenation in septic and nonseptic patients

OBJECTIVE

To evaluate the effects of pentoxifylline on hemodynamics and systemic oxygenation in septic and nonseptic critically ill patients.

DESIGN

Prospective clinical investigation.

SETTING

Intensive care unit (ICU) of a university hospital.

PATIENTS

Nineteen critically ill patients were included in the study 1 to 4 days after their admission to the ICU. A systemic inflammatory response syndrome was present in 12 patients, fulfilling at least two of the American College of Chest Physicians/ Society of Critical Care Medicine Consensus Conference criteria. The other seven patients did not fulfill these criteria and were classified as nonseptic.

INTERVENTIONS

All patients were mechanically ventilated. The dosage of catecholamines was kept constant during the entire study period and at least during 15 mins before the start of the study. In both study groups, pulmonary and radial artery catheters were inserted and 5 mg/kg of pentoxifylline (diluted in 300 mL of physiologic saline) was intravenously administered over a period of 180 mins at a rate of 100 mL/hr.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic variables, oxygen transport (DO2), oxygen uptake (VO2), and oxygen extraction ratio were determined before pentoxifylline, after 2.5 mg/kg of pentoxifylline, after 5 mg/kg of pentoxifylline, and 60 mins after the termination of pentoxifylline. Repeated-measures analysis of variance and Mann-Whitney test were used for statistical analysis. At baseline, there were significant differences between the septic and the nonseptic groups in mean pulmonary arterial pressure (septic: 31 +/- 5 mm Hg; nonseptic: 26 +/- 7 mm Hg, p < .05), and pulmonary vascular resistance index (PVRI) (septic: 344 +/- 121 dyne.sec/ cm5.m2; nonseptic: 233 +/- 100 dyne.sec/cm5.m2, p < .05). In the septic group, significant increases in heart rate and cardiac index were observed. Systemic vascular resistance index and PVRI decreased. No significant changes in hemodynamic variables occurred in the nonseptic group. In both groups, DO2 and VO2 increased significantly, while oxygen extraction ratio remained unchanged.

CONCLUSIONS

The administration of pentoxifylline to septic patients results in a significant improvement in hemodynamic performance compared with critically ill nonseptic patients. The better hemodynamic state is accompanied by an increase in DO2 and VO2 with unchanged oxygen extraction ratio.

[Definition and evaluation of a documentation standard for intensive care medicine: the ASDI(Working Group for Standardization of a documentation system for Intensive care medicine) pilot project]

OBJECTIVES

A comparison of data from different intensive care units (ICUs) needs standardized documentation. In this study the ASDI documentation standard for intensive care was tested in clinical practice. Goal of the study was to evaluate parameters and functionality required for a national, interdisciplinary documentation system for intensive care.

DESIGN

13 ICUs participated in a 4-week trial using the provided program for documentation of all admitted patients during the observation period. In addition, a questionnaire was distributed to the unit coordinators.

RESULTS

376 patients were documented in 1591 patient days. Valid SAPS II scores were found in only 29% of the discharged patients (39.1 +/- 15.5 points). Time needed for data entry exceeded preset limits (ten minutes per patient and day) in 38% of the cases. All participants affirmed the necessity of a documentation standard for intensive care, giving quality control and cost analysis as the most important reasons.

CONCLUSION

The ASDI data set fitted existing needs very closely. Only 7 out of 122 parameters (5.7%) were found to be superfluous and thus removed. Measures to reduce documentation effort to the default limits were a) a new, date orientated concept for manual recording, b) rede-sign of the user interface with new, user friendly data entry possibilities, and c) the integration of statistical analysis and reports in the documentation system. The revised data set represents a broad-based consensus, which seems to be well-suited as foundation for the national quality assurance program.

The acute respiratory distress syndrome: definitions, severity and clinical outcome. An analysis of 101 clinical investigations

OBJECTIVE

To determine possible changes in outcome from acute respiratory distress syndrome (ARDS) and to compare severity of lung injury and methods of treatment from 1967 to 1994.

DATA SOURCES

Computerized (Medline, Current Contents) and manual (Cumulated Index Medicus) literature search using the key word and/or title ARDS.

STUDY SELECTION

Only clinical studies published as full papers reporting data on both patient mortality (survival) and oxygenation index (PaO2/FIO2) were included. Single case reports, abstracts, reviews and editorials were excluded from evaluation.

DATA EXTRACTION

Relevant data were extracted in duplicate, followed by quality checks on approximately 80% of data extracted.

DATA SYNTHESIS

101 papers reporting on 3264 patients were included: 48 studies (2207 patients) were performed in the USA, 43 studies (742 patients) in Europe and 10 studies (315 patients) elsewhere. Mortality reported in these studies was 53 +/- 22% (mean +/- SD), with no apparent trend towards a higher survival (1994: 22 studies, mortality 51 +/- 19%). The mean PaO2/FIO2 ratio remained unchanged throughout the observation period (118 +/- 47 mmHg). No correlation could be established between outcome and PaO2/FIO2 or lung injury score. Patients who underwent pressure-limited ventilation had a significantly lower mortality (35 +/- 20%) than patients on volume-cycled ventilation (54 +/- 22%) or patients for whom there was no precise information on ventilatory support (59 +/- 19%). Significantly lower PaO2/FIO2 ratios (61 +/- 17 mmHg) were observed in patients prior to extracorporeal lung assist, together with mortality rates in the range of those for conventionally treated patients (55 +/- 22%).

CONCLUSIONS

The mortality of ARDS patients remained constant throughout the period studied. Therefore, the standard for outcome in ARDS should be a mortality in the 50% range. Neither PaO2/FIO2 ratio nor lung injury score was a reliable predictor for outcome in ARDS. Patients might benefit from pressure-limited ventilatory support, as well as extracorporeal lung assist. Since crucial data were missing in most clinical studies, thus preventing direct comparison, we emphasize the importance of using standardized definitions and study entry criteria.

Effectiveness of nitric oxide inhalation in septic ARDS

STUDY OBJECTIVE

To evaluate the percentage of nitric oxide (NO) responders in septic shock patients with ARDS. Additionally, to investigate long-term NO effects on cardiac performance and oxygen kinetic patterns in NO responders vs nonresponders.

DESIGN

Prospective cohort study.

SETTING

ICU of a university hospital.

PATIENTS

Twenty-five consecutive patients with a diagnosis of septic shock and established ARDS requiring inotropic and vasopressor support.

INTERVENTIONS

After diagnosis of ARDS, NO was administered at 18 or 36 ppm. Patients demonstrating a NO-induced rise of arterial oxygen tension of 20% or more and/or a fall in mean pulmonary artery pressure of 15% or more were grouped as NO responders; others were grouped as nonresponders.

MEASUREMENTS AND RESULTS

Ten patients (40%) were NO responders, while 15 patients (60%) were nonresponders. Mortality was 40% in NO responders and 67% in nonresponders (NS). NO responders developed a significantly lower mean pulmonary artery pressure (28 +/- 6 vs 33 +/- 6 mm Hg; p < 0.05), lower pulmonary vascular resistance (PVR: 258 +/- 73 vs 377 +/- 163 dyne.s.cm-5.m-2; p < 0.05), and higher PaO2/FIO2 ratio (192 +/- 85 vs 144 +/- 74 mm Hg; p < 0.05) within the study period. In responders, NO-induced afterload reduction resulted in increased right ventricular ejection fraction (RVEF: 40 +/- 7 vs 35 +/- 9%; p < 0.05), significantly higher cardiac index (CI: 4.5 +/- 1.1 vs 4.0 +/- 1.2 L.min-1.m-2; p < 0.05) and oxygen delivery (DO2: 681 +/- 141 vs 599 +/- 160 mL.min-1.m-2; p < 0.05) compared with nonresponders. In NO nonresponders, RVEF was correlated with PVR, CI, DO2, mixed venous oxygen saturation (SvO2), and oxygen extraction ratio (O2ER) (r = +/- 0.60 to +/- 0.69; p < 0.05). No significant correlation between RVEF and any of these parameters was observed in responders. SvO2 (75 +/- 7 vs 69 +/- 8%; p < 0.05) and O2ER (0.24 +/- 0.06 vs 0.27 +/- 0.06; p < 0.05) were significantly different between responders and nonresponders, while no difference in oxygen consumption was observed (161 +/- 41 vs 153 +/- 43 mL.min.m-2).

CONCLUSIONS

Inhaled NO is effective in only a subgroup of septic ARDS patients, with a higher, but insignificantly different percentage of survivors in the responder group. NO responders were characterized by increased RVEF accompanied by higher CI, DO2, and lower O2ER. In nonresponders, RVEF remained depressed, with a close correlation between RVEF and CO as well as DO2 and O2ER. Thus, nonresponders seem to suffer from impaired cardiac reserves and correspondingly lower oxygen transport variables.

Severity and outcome of ARDS: the present place of extracorporeal lung assist (ECLA)

Within the last decade extracorporeal lung assist has been recommended for the treatment of acute respiratory distress syndrome. However, this recommendation was challenged by several recent clinical studies and reviews. The goal of our analysis was therefore to investigate data on outcome and severity of gas exchange disturbance published from patients treated with ECLA. These data were compared to a historical control group consisting of ARDS patients treated conventionally. Computerized (MEDLINE 1967-95) literature search using the keywords ARDS, ECLA, ECMO, ECCO2R and HUMAN was performed. Only clinical studies published as full papers reporting data on both, patients mortality and oxygenation index (PaO2/FiO2) were included. Overall mean mortality reported was 53 +/- 22% in 17 studies (419 patients), with no apparent trend towards a higher survival within the last decade with a mean PaO2/FIO2 (14 papers; 61 +/- 17 mmHg). However, mean mortality rates of ARDS patients requiring ECLA was 52.3% and 44.9% if patients undergoing ECMO were excluded (3 papers). Therefore the mortality of these patients with severe lung injury was in the range of patients treated conventionally. Patient outcome observed in our analysis is in accordance with the mortality rates from the European ECLA centres published recently (49% in 1993). Therefore, we conclude that the mean mortality rate of patients suffering from severe ARDS treated with ECLA is in the 50% range and does not differ significantly from those of patients treated conventionally, despite significantly poorer pulmonary function.

In vivo modulation of human neutrophil function by pentoxifylline in patients with septic syndrome

The influence of pentoxifylline on human polymorphonuclear granulocyte (PMN) respiratory burst activity (RBA) was studied in 23 patients fulfilling the established criteria of sepsis and in 10 healthy donors. Pentoxifylline (PTX) was administered (5 mg/kg) by intravenous infusion in 13 septic patients over a period of 180 min. The control group consisted of 10 patients with septic syndrome who received an infusion of physiological saline. For determination of RBA, 10 mL of blood was drawn at respective time intervals before, during, and after treatment with PTX or a placebo. RBA measurements were performed using a chemiluminescence assay after stimulation of PMN with formyl-methionyl-leucyl-phenylalanine (FMLP), phorbol-myristate-acetate, and opsonized zymosan, respectively. RBA measurements of each patient were performed in replicate samples. CL was measured for 1 h at respective time intervals (1, 3, 5, 8, 10, 15 min etc). RBA of PMN of septic patients was compared with RBA of PMN of healthy donors and patients receiving PTX were compared with controls. Our results demonstrate that PMN of patients with sepsis had an increased oxidative response compared with healthy donors. We found that PTX administered intravenously was able to reduce this reactivity. RBA was significantly decreased during PTX infusion when PMN were stimulated with FMLP and phorbol-myristate-acetate, compared with the control group. No significant decrease was observed when PMN were stimulated with opsonized zymosan. These data suggest that PTX may be a valuable drug in septic state.

Optimal values for oxygen transport during hypothermia in sepsis and ARDS

Mild hypothermia (33 degrees C to 35.5 degrees C) is reported to improve oxygenation and survival in patients with lung failure (1). Although hypermetabolism may account for about 50% of the ventilatory demand in ARDS patients, the concept of reducing oxygen consumption (VO2) by lowering metabolic rate, has only recently gained attention (2). Our study was aimed to test whether mild hypothermia established by continuous veno-venous haemofiltration (CVVHF), could optimize values for oxygen kinetics in ARDS patients. Overall, we recruited 27 patients with ARDS and sepsis. Prior initiation of CVVHF patients had to meet the following criteria: a) Murray score > 2.5, and hypoxaemia with PaO2/FIO2 < 200, b) hyperthermia of > 38 degrees C, c) cardiovascular instability requiring inotropic support. Evaluation of cardio-respiratory data was performed within four different phases (I = before, II + III during and IV = after CVVHF) every 6 hours. Core temperature as derived from the thermistor of pulmonary artery catheter was aimed to be between 35.0 degrees C and 36.5 degrees C. Optimal values for oxygen delivery (DO2) (> 550 mL/min/m2) and VO2 (> 160 mL/min/m2) were defined according to Shoemaker and achieved by fluid loading, transfusion and inotropic support (3). Septic shock occurred in 10 of 14 nonsurvivors (nons) and 2 of 13 survivors (surv). Mean values for DO2 and VO2 were calculated at different body temperature ranges. While at 37 degrees C DO2 was identical between surv and nons, (663 +/- 128 versus 666 +/- 127 means +/- SD) moderate hypothermia led to a small decrease of DO2 in surv and a significant decrease in nons (632 +/- 134 versus 605 +/- 128 mL/min/m2) at 35 degrees C. Concerning VO2 during hypothermia, there was a significant drop in nonsurvivors while in survivors the decrease was less pronounced. We could demonstrate a decrease in DO2 and VO2 during mild hypothermia during CVVHF. However, decreases in nonsurvivors were more pronounced than in survivors. These results suggest that the inability to achieve optimal values for DO2 and VO2 during mild hypothermia induced by CVVHF could serve as a prognostic sign for fatal outcome. Although oxygen consumption is decreased during hypothermia, hypoxaemia may result due to alterations of the oxygen transport on a cellular basis. The relationship between oxygen transport and temperature during CVVHF therefore deserves further studies.

Right ventricular function and oxygen transport patterns in patients with acute respiratory distress syndrome

We investigated the impact of right ventricular performance on oxygen kinetics in 15 consecutive patients with acute respiratory distress syndrome. Six hundred and twenty-two complete assessments of haemodynamics, right ventricular function and oxygenation were used for evaluation. Patients were grouped as survivors (n = 8) and nonsurvivors (n = 7) and studied during four phases of lung failure. Oxygen delivery and consumption were significantly higher in survivors compared to nonsurvivors despite comparable arterial oxygen saturation. Right ventricular end-diastolic volumes were similar for both groups, while end-systolic volumes were significantly higher in nonsurvivors due to depressed ejection fraction (40.5 (SD 1.2) versus 34.4 (SD 2.8)%) during all phases of lung failure. No clinically relevant differences in right ventricular function or oxygenation were observed between periods of moderate or severe pulmonary hypertension. Nonsurvivors have depressed cardiac function caused by reduced contractility and not by inadequate right ventricular end-diastolic volume (preload) or increased pulmonary artery pressure (afterload). Maintenance of oxygen delivery in ARDS is predominantly a function of cardiac performance and not of pulmonary gas exchange.

The effects of dobutamine therapy in critically ill patients measured by transoesophageal echocardiography and intracardiac monitoring

Fourteen patients with severe hypotension and adult respiratory distress syndrome after trauma (n = 7), general surgery (n = 6) or burns (n = 1) were studied. After volume loading with 6 ml.kg-1 hydroxyethyl starch over 30 min (time I), dobutamine was infused intravenously at 5 micrograms.kg-1.min-1 (time II) and 10 micrograms.kg-1.min-1 (time III). A 5 MHz transoesophageal echocardiographic probe was used to image a standard transgastric short axis view of the left ventricle. Haemodynamic data were obtained from thermodilution studies using pulmonary flotation catheterisation. Echocardiographic measurements (off-line from videotape) and qualitative visual assessment of left ventricular function (visual assessment, on-line) were performed. All measurements were made after fluid replacement, and during infusion of the two dobutamine doses. An improvement in mean systemic arterial blood pressure and mean stroke volume occurred from time I to the end of dobutamine infusion (p < 0.05). All patients, after volume infusion, were normovolaemic according to transoesophageal echocardiography and there was a good correlation between end-diastolic area and stroke volume (r = 0.73). During dobutamine infusion, echocardiographic measurements showed no significant dose-related increase in mean (SD) percentage left ventricular short axis area change from baseline after hydroxyethyl starch (time I: 60 (2); time II: 63 (2); time III: 64 (2)). However, a significant increase in short axis area change was seen in nine of the 14 patients (67%). Analysis of the end-diastolic area/short axis area change relationship revealed a heterogeneous response to dobutamine.(ABSTRACT TRUNCATED AT 250 WORDS)