Mark R. Hemmila

Extracorporeal Life Support for Severe Acute Respiratory Distress Syndrome in Adults

Objective:Severe acute respiratory distress syndrome (ARDS) is associated with a high level of mortality. Extracorporeal life support (ECLS) during severe ARDS maintains oxygen and carbon dioxide gas exchange while providing an optimal environment for recovery of pulmonary function. Since 1989, we have used a protocol-driven algorithm for treatment of severe ARDS, which includes the use of ECLS when standard therapy fails. The objective of this study was to evaluate our experience with ECLS in adult patients with severe ARDS with respect to mortality and morbidity. Methods:We reviewed our complete experience with ELCS in adults from January 1, 1989, through December 31, 2003. Severe ARDS was defined as acute onset pulmonary failure, with bilateral infiltrates on chest x-ray, and PaO2/fraction of inspired oxygen (FiO2) ratio ≤100 or A-aDO2 >600 mm Hg despite maximal ventilator settings. The indication for ECLS was acute severe ARDS unresponsive to optimal conventional treatment. The technique of ECLS included veno-venous or veno-arterial vascular access, lung “rest” at low FiO2 and inspiratory pressure, minimal anticoagulation, and optimization of systemic oxygen delivery. Results:During the study period, ECLS was used for 405 adult patients age 17 or older. Of these 405 patients, 255 were placed on ECLS for severe ARDS refractory to all other treatment. Sixty-seven percent were weaned off ECLS, and 52% survived to hospital discharge. Multivariate logistic regression analysis identified the following pre-ELCS variables as significant independent predictors of survival: (1) age (P = 0.01); (2) gender (P = 0.048); (3) pH ≤7.10 (P = 0.01); (4) PaO2/FiO2 ratio (P = 0.03); and (5) days of mechanical ventilation (P < 0.001). None of the patients who survived required permanent mechanical ventilation or supplemental oxygen therapy. Conclusion:Extracorporeal life support for severe ARDS in adults is a successful therapeutic option in those patients who do not respond to conventional mechanical ventilator strategies.

Operative repair or endovascular stent graft in blunt traumatic thoracic aortic injuries: results of an American Association for the Surgery of Trauma Multicenter Study.

INTRODUCTION The purpose of this American Association for the Surgery of Trauma multicenter study is to assess the early efficacy and safety of endovascular stent grafts (SGs) in traumatic thoracic aortic injuries and compare outcomes with the standard operative repair (OR). PATIENTS Prospective, multicenter study. Data for the following were collected: age, blood pressure, and Glasgow Coma Scale (GCS) at admission, type of aortic injury, injury severity score, abbreviate injury scale (AIS), transfusions, survival, ventilator days, complications, and intensive care unit and hospital days. The outcomes between the two groups (open repair or SG) were compared, adjusting for presence of critical extrathoracic trauma (head, abdomen, or extremity AIS >3), GCS score </=8, systolic blood pressure <90 mm Hg, and age >55 years. Separate multivariable analysis was performed, one for patients without and one for patients with associated critical extrathoracic injuries (head, abdomen, or extremity AIS >3), to compare the outcomes of the two therapeutic modalities adjusting for hypotension, GCS score </=8, and age >55 years. RESULTS One hundred ninety-three patients met the criteria for inclusion. Overall, 125 patients (64.9%) were selected for SG and 68 (35.2%) for OR. SG was selected in 71.6% of the 74 patients with major extrathoracic injuries and in 60.0% of the 115 patients with no major extrathoracic injuries. SG patients were significantly older than OR patients. Overall, 25 patients in the SG group (20.0%) developed 32 device-related complications. There were 18 endoleaks (14.4%), 6 of which needed open repair. Procedure-related paraplegia developed in 2.9% in the OR and 0.8% in the SG groups (p = 0.28). Multivariable analysis adjusting for severe extrathoracic injuries, hypotension, GCS, and age, showed that the SG group had a significantly lower mortality (adjusted odds ratio: 8.42; 95% CI: [2.76-25.69]; adjusted p value <0.001), and fewer blood transfusions (adjusted mean difference: 4.98; 95% CI: [0.14-9.82]; adjusted p value = 0.046) than the OR group. Among the 115 patients without major extrathoracic injuries, higher mortality and higher transfusion requirements were also found in the OR group (adjusted odds ratio for mortality: 13.08; 95% CI [2.53-67.53], adjusted p value = 0.002 and adjusted mean difference in transfusion units: 4.45; 95% CI [1.39-7.51]; adjusted p value = 0.004). Among the 74 patients with major extrathoracic injuries, significantly higher mortality and pneumonia rate were found in the OR group (adjusted p values 0.04 and 0.03, respectively). Multivariate analysis showed that centers with high volume of endovascular procedures had significantly fewer systemic complications (adjusted p value 0.001), fewer local complications (adjusted p value p = 0.033), and shorter hospital lengths of stay (adjusted p value 0.005) than low-volume centers. CONCLUSIONS Most surgeons select SG for traumatic thoracic aortic ruptures, irrespective of associated injuries, injury severity, and age. SG is associated with significantly lower mortality and fewer blood transfusions, but there is a considerable risk of serious device-related complications. There is a major and urgent need for improvement of the available endovascular devices.

Diagnosis and treatment of blunt thoracic aortic injuries: changing perspectives.

BACKGROUND The diagnosis and management of blunt thoracic aortic injuries has undergone many significant changes over the last decade. The present study compares clinical practices and results between an earlier prospective multicenter study by the American Association for the Surgery of Trauma completed in 1997 (AAST1) and a new similar study completed in 2007 (AAST2). METHODS The AAST1 study included 274 patients from 50 participating centers over a period of 30 months. The AAST2 study included 193 patients from 18 centers, over a period of 26 months. The comparisons between the two studies included the method of definitive diagnosis of the aortic injury [computed tomography (CT) scan, aortography, transesophageal echocardiogram (TEE) or magnetic resonance imaging], the method of definitive aortic repair (open repair vs. endovascular repair, clamp and sew vs. bypass techniques), the time from injury to procedure (early vs. delayed repair), and outcomes (survival, procedure-related paraplegia, other complications). RESULTS There was a major shift of the method of definitive diagnosis of the aortic injury, from aortography in the AAST1 to CT scan in AAST2, and a nearly complete elimination of aortography and TEE in the AAST2 study. In the AAST2 study the diagnosis was made by CT scan in 93.3%, aortography in 8.3%, and TEE in 1.0% of patients when compared with 34.8%, 87.0%, and 11.9%, respectively, in the AAST1 study (p < 0.001). The mean time from injury to aortic repair increased from 16.5 hours in the AAST1 study to 54.6 hours in the AAST2 study (p < 0.001). In the AAST1 study, all patients were managed with open repair, whereas in the AAST2 study only 35.2% were managed with open repair and the remaining 64.8% were managed with endovascular stent-grafts. In the patients managed with open repair, the use of bypass techniques increased from 64.7% to 83.8%. The overall mortality, excluding patients in extremis, decreased significantly from 22.0% to 13.0% (p = 0.02). Also, the incidence of procedure-related paraplegia in patients with planned operation, decreased from 8.7% to 1.6% (p = 0.001). However, the incidence of early graft-related complications increased from 0.5% in the AAST1 to 18.4% in the AAST2 study. CONCLUSIONS Comparison between the two AAST studies in 1997 and 2007 showed a major shift in the diagnosis of the aortic injury, with the widespread use of CT scan and the almost complete elimination of aortography and TEE. The concept of delayed definitive repair has gained wide acceptance. Endovascular repair has replaced open repair to a great extent. These changes have resulted in a major reduction of mortality and procedure-related paraplegia but also a significant increase of early graft-related complications.

Extracorporeal support for organ donation after cardiac death effectively expands the donor pool.

Background:We sought to evaluate the effect on short-term outcomes of normothermic, extracorporeal perfusion (ECMO) for donation of abdominal organs for transplantation after cardiac death (DCD). Study parameters included increase in number of donors and organs, types of organs procured, and viabili

A review of 100 patients transported on extracorporeal life support.

Between May 1990 and January 1999, 100 patients (68 adult, 32 pediatric) with severe respiratory or cardiac instability were successfully transported to the University of Michigan Medical Center on extracorporeal life support. Diagnoses included adult respiratory distress syndrome (n = 78), cardiac failure (n = 7), sepsis (n = 7), asthma (n = 5), respiratory distress syndrome (of newborn) (n = 2), and airway compromise (n = 1). Of the patients, 53 were supported with venovenous bypass and 47 with venoarterial bypass. Patients were transported by ground ambulance (n = 80), helicopter (n = 15), or fixed-wing aircraft (n = 5). The median transport distance was 44 miles (range 2–790 miles), and the median transport time was 5 hours and 30 minutes (range: 1 h 33 min to 16 h 6 min). Sixty-six patients (66%) survived to discharge. One death occurred during cannulation, and two patients died before cannulation began. Complications that occurred during transport included 10 cases of electrical failure, 3 cases of circuit tubing leakage, and 1 case each of circuit rupture, membrane lung thrombosis, and membrane lung leakage. None of the complications occurring during transport had an adverse effect on outcome. We conclude that the long distance transport of patients on extracorporeal life support can be safely accomplished and is an effective option for the unstable patient with severe respiratory or cardiac failure.

An essential role for complement C5a in the pathogenesis of septic cardiac dysfunction

Defective cardiac function during sepsis has been referred to as “cardiomyopathy of sepsis.” It is known that sepsis leads to intensive activation of the complement system. In the current study, cardiac function and cardiomyocyte contractility have been evaluated in rats after cecal ligation and puncture (CLP). Significant reductions in left ventricular pressures occurred in vivo and in cardiomyocyte contractility in vitro. These defects were prevented in CLP rats given blocking antibody to C5a. Both mRNA and protein for the C5a receptor (C5aR) were constitutively expressed on cardiomyocytes; both increased as a function of time after CLP. In vitro addition of recombinant rat C5a induced dramatic contractile dysfunction in both sham and CLP cardiomyocytes, but to a consistently greater degree in cells from CLP animals. These data suggest that CLP induces C5aR on cardiomyocytes and that in vivo generation of C5a causes C5a–C5aR interaction, causing dysfunction of cardiomyocytes, resulting in compromise of cardiac performance.

Blunt Traumatic Thoracic Aortic Injuries: Early or Delayed Repair—results of an American Association for the Surgery of Trauma Prospective Study

BACKGROUND The traditional approach to stable blunt thoracic aortic injuries (TAI) is immediate repair, with delayed repair reserved for patients with major associated injuries. In recent years, there has been a trend toward delayed repair, even in low-risk patients. This study evaluates the current practices in the surgical community regarding the timing of aortic repair and its effects on outcomes. METHODS This was a prospective, observational multicenter study sponsored by the American Association for the Surgery of Trauma. The study included patients with blunt TAI scheduled for aortic repair by open or endovascular procedure. Patients in extremis and those managed without aortic repair were excluded. The data collection included demographics, initial clinical presentation, Injury Severity Scores, type and site of aortic injury, type of aortic repair (open or endovascular repair), and time from injury to aortic repair. The study patients were divided into an early repair (< or = 24 hours) and delayed repair groups (> 24 hours). The outcome variables included survival, ventilator days, intensive care unit (ICU) and hospital lengths of stay, blood transfusions, and complications. The outcomes in the two groups were compared with multivariate analysis after adjusting for age, Glasgow Coma Scale, hypotension, major associated injuries, and type of aortic repair. A second multivariate analysis compared outcomes between early and delayed repair, in patients with and patients without major associated injuries. RESULTS There were 178 patients with TAI eligible for inclusion and analysis, 109 (61.2%) of which underwent early repair and 69 (38.8%) delayed repair. The two groups had similar epidemiologic, injury severity, and type of repair characteristics. The adjusted mortality was significantly higher in the early repair group (adjusted OR [95% CI] 7.78 [1.69-35.70], adjusted p value = 0.008). The adjusted complication rate was similar in the two groups. However, delayed repair was associated with significantly longer ICU and hospital lengths of stay. Analysis of the 108 patients without major associated injuries, adjusting for age, Glasgow Coma Scale, hypotension, and type of aortic repair, showed that in early repair there was a trend toward higher mortality rate (adjusted OR 9.08 [0.88-93.78], adjusted p value = 0.064) but a significantly lower complication rate (adjusted OR 0.4 [0.18-0.96], adjusted p value 0.040) and shorter ICU stay (adjusted p value = 0.021) than the delayed repair group. A similar analysis of the 68 patients with major associated injuries, showed a strong trend toward higher mortality in the early repair group (adjusted OR 9.39 [0.93-95.18], adjusted p value = 0.058). The complication rate was similar in both groups (adjusted p value = 0.239). CONCLUSIONS Delayed repair of stable blunt TAI is associated with improved survival, irrespective of the presence or not of major associated injuries. However, delayed repair is associated with a longer length of ICU stay and in the group of patients with no major associated injuries a significantly higher complication rate.

Introduction to propensity scores: A case study on the comparative effectiveness of laparoscopic vs open appendectomy.

OBJECTIVE To demonstrate the use of propensity scores to evaluate the comparative effectiveness of laparoscopic and open appendectomy. DESIGN Retrospective cohort study. SETTING Academic and private hospitals. PATIENTS All patients undergoing open or laparoscopic appendectomy (n = 21 475) in the Public Use File of the American College of Surgeons National Surgical Quality Improvement Program were included in the study. We first evaluated the surgical approach (laparoscopic vs open) using multivariate logistic regression. We next generated propensity scores and compared outcomes for open and laparoscopic appendectomy in a 1:1 matched cohort. Covariates in the model for propensity scores included comorbidities, age, sex, race, and evidence of perforation. MAIN OUTCOME MEASURES Patient morbidity and mortality, rate of return to operating room, and hospital length of stay. RESULTS Twenty-eight percent of patients underwent open appendectomy, and 72% had a laparoscopic approach; 33% (open) vs 14% (laparoscopic) had evidence of a ruptured appendix. In the propensity-matched cohort, there was no difference in mortality (0.3% vs 0.2%), reoperation (1.8% vs 1.5%), or incidence of major complications (5.9% vs 5.4%) between groups. Patients undergoing laparoscopic appendectomy experienced fewer wound infections (odds ratio [OR], 0.4; 95% confidence interval [CI], 0.3-0.5) and fewer episodes of sepsis (0.8; 0.6-1.0) but had a greater risk of intra-abdominal abscess (1.7; 1.3-2.2). An analysis using multivariate adjustment resulted in similar findings. CONCLUSIONS After accounting for patient severity, open and laparoscopic appendectomy had similar clinical outcomes. In this case study, propensity score methods and multivariate adjustment yielded nearly identical results.

Real money: Complications and hospital costs in trauma patients

BACKGROUND Major postoperative complications are associated with a substantial increase in hospital costs. Trauma patients are known to have a higher rate of complications than the general surgery population. We used the National Surgical Quality Improvement Program (NSQIP) methodology to evaluate hospital costs, duration of stay, and payment associated with complications in trauma patients. METHODS Using NSQIP principles, patient data were collected for 512 adult patients admitted to the trauma service for > 24 hours at a Level 1 trauma center (2004-2005). Patients were placed in 1 of 3 groups: no complications (none), >or=1 minor complication (minor, eg, urinary tract infection), or >or=1 major complication (major, eg, pneumonia). Total hospital charges, costs, payment, and duration of stay associated with each complication group were determined from a cost-accounting database. Multiple regression was used to determine the costs of each type of complication after adjusting for differences in age, sex, new injury severity score, Glasgow coma scale score, maximum head abbreviated injury scale, and first emergency department systolic blood pressure. RESULTS A total of 330 (64%) patients had no complications, 53 (10%) had >or= 1 minor complication, and 129 (25%) had >or= 1 major complication. Median hospital charges increased from

Angioembolization reduces operative intervention for blunt splenic injury.

33,833 (none) to