Srinivas Kolla

Extracorporeal life support in pulmonary failure after trauma

OBJECTIVE To present a series of 30 adult trauma patients who received extracorporeal life support (ECLS) for pulmonary failure and to retrospectively review variables related to their outcome. METHODS In a Level I trauma center between 1989 and 1997, ECLS with continuous heparin anticoagulation was instituted in 30 injured patients older than 15 years. Indication was for an estimated mortality risk greater than 80%, defined by a PaO2: FIO2 ratio less than 100 on 100% FIO2, despite pressure-mode inverse ratio ventilation, optimal positive end-expiratory pressure, reasonable diuresis, transfusion, and prone positioning. Retrospective analysis included demographic information (age, gender, Injury Severity Score, injury mechanism), pulmonary physiologic and gas-exchange values (pre-ECLS ventilator days [VENT days], PaO2:FIO2 ratio, mixed venous oxygen saturation [SvO2], and blood gas), pre-ECLS cardiopulmonary resuscitation, complications of ECLS (bleeding, circuit problems, leukopenia, infection, pneumothorax, acute renal failure, and pressors on ECLS), and survival. RESULTS The subjects were 26.3+/-2.1 years old (range, 15-59 years), 50% male, and had blunt injury in 83.3%. Pulmonary recovery sufficient to wean the patient from ECLS occurred in 17 patients (56.7%), and 50% survived to discharge. Fewer VENT days and more normal SvO2 were associated with survival. The presence of acute renal failure and the need for venoarterial support (venoarterial bypass) were more common in the patients who died. Bleeding complications (requiring intervention or additional transfusion) occurred in 58.6% of patients and were not associated with mortality. Early use of ECLS (VENT days < or = 5) was associated with an odds ratio of 7.2 for survival. Fewer VENT days was independently associated with survival in a logistic regression model (p = 0.029). Age, Injury Severity Score, and PaO2:FIO2 ratio were not related to outcome. CONCLUSION ECLS has been safely used in adult trauma patients with multiple injuries and severe pulmonary failure. In our series, early implementation of ECLS was associated with improved survival. Although this may represent selection bias for less intractable forms of acute respiratory distress syndrome, it is our experience that early institution of ECLS may lead to improved oxygen delivery, diminished ventilator-induced lung injury, and improved survival.

Extracorporeal life support outcome for 128 pediatric patients with respiratory failure.

PURPOSE The aim of this study was to describe a single-center experience with pediatric extracorporeal life support (ECLS) and to determine variables predictive of outcome in pediatric patients, both before the institution of ECLS and while on support. METHODS From October 1985 to September 1998 the authors supported 128 children with severe acute hypoxemic respiratory failure(n = 121, Pao2/FIo2 ratio = 58+/-29) or acute hypercarbic respiratory failure (n = 7, Paco2 = 128+/-37), despite maximal conventional ventilation. Mode of access included venoarterial bypass (VA, n = 64), venovenous bypass (VV, n = 53), and VV to VA bypass (n = 11). The techniques used included lung rest, pulmonary physiotherapy, diuresis to dry weight using hemofiltration if needed, minimal anticoagulation, and optimal systemic oxygen delivery. RESULTS The median age was 1.4 years (range, 2 weeks to 17 years). The mean duration of ECLS was 288+/-240 hours (range, 4 to 1148 hours or 0.2 to 47.8 days). Lung compliance increased from 0.32+/-0.02 mL/cm H2O/kg to 0.59+/-0.03 mL/cm H2O/kg in survivors, but only increased from 0.34+/-0.02 mL/cm H2O/kg to 0.35+/-0.02 mL/cm H2O/kg in nonsurvivors (P<.002 comparing change between survivors and nonsurvivors). Mean body weight decreased from 9%+/-2% over dry weight to 4%+/-2% in survivors, whereas in nonsurvivors the mean body weight increased from 25%+/-5% over dry weight to 35%+/-7% (P<.001). Outcome results by diagnosis were pneumonia, 73%; acute respiratory distress syndrome, 67%; and airway support, 60%, with overall lung recovery occurring in 77%, and hospital survival in 71%. Multivariate logistic regression modelling of patients with hypoxemic respiratory failure found the only pre-ECLS variable significantly associated with outcome to be pH (P<.05). Variables during the course of ECLS significantly associated with decreased survival were the presence of creatinine greater than 3.0 (P<.01), the need for inotropes (P<.04), failure to return the patient to dry weight (P<.04), and lung compliance that did not improve significantly. (P<.01). CONCLUSIONS ECLS provides life support in severe respiratory failure in children, allowing time for injured lungs to recover. Pre-ECLS predictors, such as pH and variables during ECLS, such as presence of renal failure, improvement in compliance, return to dry weight, and the need for inotropes on ECLS, may be useful for predicting outcome.

Extracorporeal life support for cardiovascular support in adults

The authors retrospectively reviewed their institutions experience with extracorporeal life support (ECLS) for adult cardiovascular failure to determine efficacy and further indications for its use. From 1985 to 1996, venoarterial ECLS was used in 27 adult patients. Indications for ECLS included post cardiotomy cardiac failure, primary myocardial failure, bridge to transplant, and emergency cardiopulmonary resuscitation. The average age was 38.7 +/- 2.7 years and duration of support was 164.0 +/- 26.8 hr. Overall cardiovascular recovery from ECLS was 44%, and hospital survival was 30%. Late deaths were due to multisystem organ failure. Best results were obtained in patients whose processes were reversible during a short duration of ECLS (< 91.6 +/- 33.3 hr. The worst results were obtained in post cardiotomy patients who underwent prolonged support with ECLS. Evaluation of physiologic parameters during the first 30-48 hr of support showed marked improvements from values before ECLS. Because of its relative ease of deployment and its rapid correction of acute physiologic derangements, ECLS can be used as a temporary means of support to determine extent and reversibility of organ dysfunction. Longer term support should include consideration of other mechanical assist devices. The authors no longer consider bridge to transplant an indication for ECLS due to relative donor unavailability.

Characteristics of an albumin dialysate hemodiafiltration system for the clearance of unconjugated bilirubin.

Extraction of protein bound liver failure toxins, such as unconjugated bilirubin, short chain fatty acids, and aromatic amino acids has been reported using hemodiafiltration with albumin in the dialysate, but the characteristics of such a system have not been described. Therefore, bilirubin clearance using albumin dialysate hemodiafiltration was evaluated in the setting of different dialysate albumin concentrations, varying temperature, and pH. An in vitro continuous hemodiafiltration circuit was used with single pass countercurrent dialysis. Unconjugated bilirubin was added to bovine blood and filtered across a polyalkyl sulfone (PAS) hemofilter using matched filtration and dialysate flow rates. The serial bilirubin content was measured and first order clearance kinetics verified. The clearance rate constants were calculated for three dialysate groups of different albumin concentration at constant temperature and pH (group 1:10 g/dl albumin, n = 5; 2 g/dl albumin, n = 5; normal saline, n = 5), and three groups of different temperature and pH at constant albumin dialysate concentration (group 2: pH = 7.0, temperature = 20° C, n = 5; pH = 7.5, temperature = 20° C, n = 5; pH = 7.0, temperature = 40° C, n = 5). Comparisons were made with ANOVA and Tukey post hoc analysis. When albumin was used in the dialysate, the 2 g/dl group cleared bilirubin 3.1 times faster than saline alone (p = 0.001), and the 10 g/dl group was superior to both (p = 0.001). There were no measurable differences between the 2 g/dl groups at the various temperatures tested (p = 0.08), but the clearance was less at a pH of 7.5 (p = 0.015). The clearance of unconjugated bilirubin is greatly enhanced with the use of albumin containing dialysates when compared to traditional crystalloid hemodiafiltration, is greater at lower pH, and seems to be unaffected by temperature. ASAIO Journal 1997; 43:M745-M749.

An approach to the treatment of severe adult respiratory failure

OBJECTIVES The purpose of this article is to evaluate outcome in adult patients with severe respiratory failure managed with an approach using (1) limitation of end inspiratory pressure, (2) inverse ratio ventilation, (3) titration of PEEP by SvO2, (4) intermittent prone positioning, (5) limitation of FiO2, (6) diuresis, (7) transfusion, and (8) extracorporeal life support (ECLS) if patients failed to respond. PATIENTS AND METHODS This study was designed as a retrospective review in the intensive care unit of a tertiary referral hospital. One-hundred forty-one consecutive patients with hypoxic (n = 135) or hypercarbic (n = 6) respiratory failure referred for consideration of ECLS between 1990 and 1996. Overall, initial PaO2/FiO2 (P/F) ratio was 75+/-5 (median = 66). RESULTS Lung recovery occurred in 67% of patients and 62% survived. Forty-one patients improved without ECLS (83% survived); 100 did not and were supported with ECLS (54% survived). Survival was greater in patients cannulated within 12 hours of arrival (59%) compared with those cannulated after 12 hours (40%, P < .05). Multiple logistic regression identified age, duration of mechanical ventilation before transfer, four or more dysfunctional organs, and the requirement for ECLS as independent predictors of mortality. CONCLUSIONS An approach that emphasizes lung protection and early implementation of extracorporeal life support is associated with high rates of survival in patients with severe respiratory failure.

Prolonged extracorporeal life support (ECLS) for varicella pneumonia

Objective To review the institutional experience of a national tertiary referral center for extracorporeal life support (ECLS) in severe varicella pneumonia.Data Sources Hospital records and ECLS flow sheets.Study Selection All pediatric (nonneonatal) and adult patients who were treated for varicell

Total respiratory support with tidal flow extracorporeal circulation in adult sheep

A novel pressure gated tidal flow extracorporeal circulation (TF ECC) device was developed, and it was hypothesized that it could provide total respiratory support in apneic adult sheep without adverse hemodynamic or cardiac effects. The circuit consisted of a single lumen cannula, computer driven tubing occluders gated by circuit pressure, a nonocclusive peristaltic blood pump, a spiral coiled membrane lung, and a heat exchanger. Six paralyzed, anesthetized adult sheep were instrumented and TF ECC was instituted via cannulation of the right atrium. Total respiratory support was provided by the circuit during an apneic period of 6 hours. Echocardiography was performed with the animal instrumented (baseline) and after 2 hours of TF ECC. Circuit blood tidal volume was 172.6 ± 18.0 cc, resulting in a TF ECC flow of 71.1 ± 10.1 cc/kg/min. At the end of the study period, PaCo2 was 35.5 ± 7.6 mmHg, pa O2) was 91.2 ± 30.6 mmHg, and pulmonary artery oxygen saturation (SPAO2) was 95 ± 5%. Hemodynamic stability was maintained with no significant differences at baseline and after 6 hours in mean arterial pressure, mean pulmonary artery pressure, or heart rate noted. Echocardiographic evaluation showed preserved fractional shortening of the left ventricular (LV) septal-lateral dimension (baseline 32.4 ± 11.4 %; 2 hours 34.8 ± 8.4 %). This study demonstrates TF ECC provides total respiratory support without adverse hemodynamic effects, and preserved LV function. ASAIO Journal 1997; 43:M811-M816.

PROLONGED EXTRA CORPOREAL LIFE SUPPORT (ECLS) FOR VARICELLA PNEUMONIA

OBJECTIVE To review the institutional experience of a national tertiary referral center for extracorporeal life support (ECLS) in severe varicella pneumonia. DATA SOURCES Hospital records and ECLS flow sheets. STUDY SELECTION All pediatric (nonneonatal) and adult patients who were treated for varicella pneumonia with ECLS at the University of Michigan Medical Center between 1986 and 1995. DATA EXTRACTION Diagnosis of varicella pneumonia was made by history of recent exposure to chickenpox, progressive dyspnea, fever, a characteristic diffuse, vesicular rash, and a supporting chest roentgenogram. Indications for ECLS included a shunt fraction of > 30% or PaO2/FlO2 ratio of < 80 despite maximal conventional therapy, which included aggressive diuresis, blood transfusions to optimize oxygen-carrying capacity, pressure-controlled/inverse-ratio ventilation, and intermittent prone positioning. DATA SYNTHESIS Between 1986 and 1995, 191 patients were referred for ECLS. Among these patients, there were 51 (27%) cases of viral pneumonia, of which nine cases were due to acute varicella-zoster infection. Intravenous acyclovir was administered to eight of the nine patients. Of the nine patients, two patients improved using conventional ventilator management, and seven patients underwent ECLS. Overall survival on ECLS was 71% (5/7). The mean (+/-SD) alveolar-arterial oxygen gradient and PaO2/FlO2 ratio were 533 +/- 101 torr (71.3 +/- 13.5 kPa) and 67 +/- 24, respectively. The median duration of mechanical ventilation before ECLS and the subsequent duration of ECLS were 4 and 12.8 days, respectively. One of the deaths was from progressive right heart failure secondary to pulmonary hypertension and the other death was from overwhelming Pseudomonas sepsis. CONCLUSIONS Early recognition of imminent pulmonary failure and rapid institution of ECLS are critical in the successful management of severe, life-threatening varicella pneumonia.