Disaster Preparedness and Response for the Burn Mass Casualty Incident in the Twenty-first Century

The effective and efficient coordination of emergent patient care at the point of injury followed by the systematic resource-based triage of casualties are the most critical factors that influence patient outcomes after mass casualty incidents (MCIs). The effectiveness and appropriateness of implemented actions are largely determined by the extent and efficacy of the planning and preparation that occur before the MCI. The goal of this work was to define the essential efforts related to planning, preparation, and execution of acute and subacute medical care for disaster burn casualties. This type of MCI is frequently referred to as a burn MCI."

Deployable, portable, and temporary hospitals; one state's experiences through the years

This article will review the use of temporary hospitals to augment the healthcare system as one solution for dealing with a surge of patients related to war, pandemic disease outbreaks, or natural disaster. The experiences highlighted in this article are those of North Carolina (NC) over the past 150 years, with a special focus on the need following the September 11, 2001 (9/11) attacks. It will also discuss the development of a temporary hospital system from concept to deployment, highlight recent developments, emphasize the need to learn from past experiences, and offer potential solutions for assuring program sustainability. Historically, when a particular situation called for a temporary hospital, one was created, but it was usually specific for the event and then dismantled. As with the case with many historical events, the details of the 9/11 attacks will fade into memory, and there is a concern that the impetus which created the current temporary hospital program may fade, as well. By developing a broader and more comprehensive approach to disaster responses through all-hazards preparedness, it is reasonable to learn from these past experiences, improve the understanding of current threats, and develop a long-term strategy to sustain these resources for future disaster medical needs.

Health care: economic impact of caring for geriatric patients

National health care expenditures constitute a continuously expanding component of the US economy. Health care resources are distributed unequally among the population, and geriatric patients are disproportionately represented. Characterizing this group of individuals that accounts for the largest percentage of US health spending may facilitate the introduction of targeted interventions in key high-impact areas. Changing demographics, an increasing incidence of chronic disease and progressive disability, rapid technological advances, and systemic market failures in the health care sector combine to drive cost. A multidisciplinary approach will become increasingly necessary to balance the delicate relationship between our constrained supply and increasing demand.

Hospital bioterrorism planning and burn surge

On the morning of June 9, 2009, an explosion occurred at a manufacturing plant in Garner, North Carolina. By the end of the day, 68 injured patients had been evaluated at the 3 Level I trauma centers and 3 community hospitals in the Raleigh/Durham metro area (3 people who were buried in the structural collapse died at the scene). Approximately 300 employees were present at the time of the explosion, when natural gas being vented during the repair of a hot water heater ignited. The concussion from the explosion led to structural failure in multiple locations and breached additional natural gas, electrical, and ammonia lines that ran overhead in the 1-story concrete industrial plant. Intent is the major difference between this type of accident and a terrorist using an incendiary device to terrorize a targeted population. But while this disaster lacked intent, the response, rescue, and outcomes were improved as a result of bioterrorism preparedness. This article discusses how bioterrorism hospital preparedness planning, with an all-hazards approach, became the basis for coordinated burn surge disaster preparedness. This real-world disaster challenged a variety of systems, hospitals, and healthcare providers to work efficiently and effectively to manage multiple survivors. Burn-injured patients served as a focus for this work. We describe the response, rescue, and resuscitation provided by first responders and first receivers as well as efforts made to develop burn care capabilities and surge capacity.

Use of the novel hemostatic textile Stasilon(R) to arrest refractory retroperitoneal hemorrhage: a case report

Introduction

Stasilon^® is a novel hemostatic woven textile composed of allergen-free fibers of continuous filament fiberglass and bamboo yarn. The development of this product resulted from controlled in vitro thrombogenic analysis of an array of potentially hemostatic textile materials and it has been cleared for both external and internal use by the United States Food and Drug Administration for the arrest of hemorrhage. The goal of the study was to assess the hemostatic and adhesive properties of Stasilon^® in the setting of life-threatening refractory hemorrhage.

Case presentation

A 39-year-old Caucasian man presented with severe necrotic pancreatitis that failed multiple aggressive attempts to control associated bleeding with electrocautery, suture ligation, and sequential anatomic packing with cotton-based sponges. Subsequent retroperitoneal packing with Stasilon^® produced a non-adherent wound-dressing interface and resulted in the achievement of persistent hemostasis in the operative field.

Conclusion

In our patient, Stasilon^® was demonstrated to be effective in the arrest of refractory hemorrhage.

North Carolina all-terrain vehicle (ATV) safety legislation: an assessment of the short-term impact on ATV-related morbidity and mortality

OBJECTIVE

All-terrain vehicle (ATV)-related morbidity and mortality has increased in the US, and states have attempted to combat this trend with ATV-specific safety legislation. The objective of this study was to examine the short-term changes in ATV-related injuries and deaths following the enactment of legislation regulating the operation and sale of ATVs in North Carolina.

STUDY DESIGN AND DATA COLLECTION

The study is a retrospective analysis comparing ATV collisions during the six month pre and post period of the effective date of legislation. Demographics, medical outcomes, passenger seat position, helmet use, and alcohol use were analyzed.

DATA

Subjects were identified through the North Carolina Trauma Registry and data from the Office of the Chief Medical Examiner.

FINDINGS

A total of 102 (51 in both pre- and post-legislation) subjects required medical treatment or were declared dead secondary to ATV collisions in North Carolina. Children under the age of eight years, who were forbidden from using ATVs under the new legislation, had significantly fewer total medical evaluations and deaths in the post-legislative time period. There was no association between legislative time period and ATV-related passenger, helmet, or alcohol use.

CONCLUSIONS

In the six months following the enactment of North Carolina's ATV bill, children under the age of eight years were seriously injured or died less often due to ATV-related crashes. No other significant changes in ATV riding patterns were seen between the two time periods, and the morbidity and mortality of all ATV riders did not change.

LIMITATIONS

The examined data sets do not include data from all North Carolina hospitals.

The design and testing of a dual fiber textile matrix for accelerating surface hemostasis

The standard treatment for severe traumatic injury is frequently compression and application of gauze dressing to the site of hemorrhage. However, while able to rapidly absorb pools of shed blood, gauze fails to provide strong surface (topical) hemostasis. The result can be excess hemorrhage-related morbidity and mortality. We hypothesized that cost-effective materials (based on widespread availability of bulk fibers for other commercial uses) could be designed based on fundamental hemostatic principles to partially emulate the wicking properties of gauze while concurrently stimulating superior hemostasis. A panel of readily available textile fibers was screened for the ability to activate platelets and the intrinsic coagulation cascade in vitro. Type E continuous filament glass and a specialty rayon fiber were identified from the material panel as accelerators of hemostatic reactions and were custom woven to produce a dual fiber textile bandage. The glass component strongly activated platelets while the specialty rayon agglutinated red blood cells. In comparison with gauze in vitro, the dual fiber textile significantly enhanced the rate of thrombin generation, clot generation as measured by thromboelastography, adhesive protein adsorption and cellular attachment and activation. These results indicate that hemostatic textiles can be designed that mimic gauze in form but surpass gauze in ability to accelerate hemostatic reactions.

Nonfocused enhanced CT evaluation of acute appendicitis increases length of stay in the emergency department but does not increase perforation rate

Nonfocused enhanced CT (NFECT) using intravenous and oral contrast is highly sensitive and specific for the diagnosis of acute appendicitis but requires additional time for transit of oral contrast and imaging interpretation. The aim of this study was to review our use of NFECT for the evaluation of acute appendicitis. Over a 2-year period, 295 adult patients presented to our emergency department and were diagnosed with acute appendicitis. Of these patients, 240 (81%) had undergone some form of cross-sectional imaging of the abdomen, and the majority (n = 193 [65%]) had NFECT scans performed during their evaluation. Fifty-five (19%) patients did not undergo cross-sectional radiographic evaluation (nonimaging group). Compared with the nonimaging group, patients who underwent NFECT were older (37 vs 32 years; P = 0.015) and more likely to be female (49% vs 20%; P < 0.001). Length of stay in the emergency department was significantly greater for patients who underwent NFECT (606 vs 321 minutes; P < 0.001), but there was no significant difference in the rate of acute appendiceal perforation (15% vs 9%; P = 0.297). In conclusion, use of NFECT for the diagnosis of acute appendicitis nearly doubles the patient's time in the emergency department with no significant increase in the acute perforation rate.

Nonfocused Enhanced CT Evaluation of Acute Appendicitis Increases Length of Stay in the Emergency Department but Does Not Increase Perforation Rate

Nonfocused enhanced CT (NFECT) using intravenous and oral contrast is highly sensitive and specific for the diagnosis of acute appendicitis but requires additional time for transit of oral contrast and imaging interpretation. The aim of this study was to review our use of NFECT for the evaluation of acute appendicitis. Over a 2-year period, 295 adult patients presented to our emergency department and were diagnosed with acute appendicitis. Of these patients, 240 (81%) had undergone some form of cross-sectional imaging of the abdomen, and the majority (n = 193 [65%]) had NFECT scans performed during their evaluation. Fifty-five (19%) patients did not undergo cross-sectional radiographic evaluation (nonimaging group). Compared with the nonimaging group, patients who underwent NFECT were older (37 vs 32 years; P = 0.015) and more likely to be female (49% vs 20%; P < 0.001). Length of stay in the emergency department was significantly greater for patients who underwent NFECT (606 vs 321 minutes; P < 0.001), but there was no significant difference in the rate of acute appendiceal perforation (15% vs 9%; P = 0.297). In conclusion, use of NFECT for the diagnosis of acute appendicitis nearly doubles the patient's time in the emergency department with no significant increase in the acute perforation rate.

Volunteerism among surgeons: an exploration of attitudes and barriers

BACKGROUND

In a recent survey, the American College of Surgeons found great interest in surgically related volunteerism, but it was unclear if the interest reflected participation. The purpose of the current study was to explore attitudes and barriers to volunteering.

METHODS

To assess surgeons' experiences and beliefs about volunteerism, we mailed a questionnaire to Nathan A. Womack Society members. We analyzed respondents' demographics and attitudes, and associations between physician characteristics and volunteer status.

RESULTS

The response rate was 42.5%. More than half (56%) of respondents volunteered surgical skills at least once, and 48% actively volunteer a mean of 9 days per year. Full-time practicing status was associated with being an active volunteer (57.8% vs 17.2% not full-time, P <.001). Modifiable barriers were identified.

CONCLUSIONS

Many different kinds of surgeons volunteer their surgical skills, reflecting the interest found by the College. Knowledge of barriers can be used to develop strategies to help interested surgeons pursue volunteer interests.

Intestinal ischemia-reperfusion injury alters purinergic receptor expression in clinically relevant extraintestinal organs

BACKGROUND

Intestinal ischemia-reperfusion (IIR) injury is known to initiate the systemic inflammatory response syndrome, which often progresses to multiple organ failure. We investigated changes in purinoceptor expression in clinically relevant extra-intestinal organs following IIR injury.

MATERIALS AND METHODS

Anesthetized adult male BalbC mice were randomized to sham laparotomy (control, n = 5), or 15 min of superior mesenteric artery occlusion. Experimental ischemia was followed by a period of reperfusion [1 min (n = 6) or 1 h (n = 6)]. Mice were then sacrificed and lung, kidney, and intestinal tissues were harvested. Following RNA extraction, purinoceptor mRNA expression for P2Y2, A3, P2X7, A2b, P2Y4, and P2Y6 was analyzed using real-time RT-PCR.

RESULTS

Significant differences in purinoceptor expression were observed in the lungs and kidneys of mice exposed to IIR injury when compared to controls. Pulmonary P2Y2 receptor expression was increased in the 1 h IIR group when compared to control, while pulmonary A3 receptor expression was incrementally elevated following IIR injury. In the kidney, P2Y2 receptor expression was increased in the 1 h IIR group compared to both 1 min IIR and control, and A3 receptor expression was decreased in the 1 h IIR group compared to the 1 min IIR group. No significant changes were observed in the intestinal purinoceptor profiles.

CONCLUSION

Purinoceptor expression is altered in the murine lung and kidney, but not intestine following experimental IIR injury. These findings may implicate extracellular nucleotides and purinoceptors as possible mediators of the extra-intestinal organ dysfunction associated with IIR injury.

Extracorporeal life support for severe adult respiratory failure

PURPOSE OF REVIEW

The past 35 years have provided a wealth of evidence that mechanical ventilation, although potentially life saving, can injure the lungs. Recent evidence suggests that limiting ventilating gas volumes can reduce patient mortality, but may result in progressive parenchymal derecruitment and alveolar hypoventilation, potentially aggravating systemic hypercarbia and hypoxemia. This review summarizes the current recommendations on a controversial, invasive technique termed 'extracorporeal life support' as a means to provide temporary pulmonary support during 'lung-protective' strategies.

RECENT FINDINGS

Extracorporeal life support has been implemented since the origins of cardiopulmonary bypass in the 1950s, but differs in several important ways from cardiopulmonary bypass, including its prolonged duration of application. Because extracorporeal life support serves only to supplement physiological derangements and is not therapeutic, patient selection critically impacts results. Whereas reversible neonatal processes such as meconium aspiration and persistent fetal circulation have fostered clinical trials demonstrating the efficacy of extracorporeal life support, adult cardiopulmonary failure extracorporeal life support trials have proved less compelling. Despite two prospective randomized trials that failed to demonstrate its efficacy, adult extracorporeal life support continues in limited centers of excellence. Adult extracorporeal life support survival rates for respiratory failure average 50% when strict criteria are met, but it remains unclear whether these results represent improved outcomes.

SUMMARY

Extracorporeal life support is an invasive technique that can provide support to the failing lung. Clinical trials have demonstrated its efficacy in neonatal and pediatric patients, but data in adults are less clear. An ongoing trial in the UK will soon address this important issue.

Postoperative pulmonary complications

PURPOSE OF REVIEW

Postoperative pulmonary complications, including pneumonia, bronchospasm, respiratory failure and prolonged mechanical ventilation, occur commonly and are a significant source of morbidity and mortality. This review will discuss the etiology of postoperative pulmonary complications and the interventions that reduce their risk.

RECENT FINDINGS

General anesthesia and surgery produce changes in the respiratory system and are responsible, along with underlying conditions, for postoperative pulmonary complications. Risk factors include upper abdominal or thoracic surgery, cigarette smoking, chronic respiratory disease, emergency surgery, anesthetic time of 180 min or more, age greater than 70 years, renal failure, poor nutritional status, and significant intraoperative blood loss. The inhibition of phrenic nerve output results in postoperative diaphragmatic dysfunction. Sleep-disordered breathing occurs after surgery even in patients without obstructive sleep apnea, but patients with obstructive sleep apnea may have a worsening of their disease after surgery. A clear advantage of one anesthetic technique over another in reducing postoperative pulmonary complications has not been demonstrated. Conflicting results have been obtained regarding the value of epidural analgesia in preventing postoperative pulmonary complications. Incentive spirometry decreases rates of postoperative pulmonary complications and hospital lengths of stay.

SUMMARY

Understanding risk factors for the development of postoperative pulmonary complications allows targeted interventions aimed at reducing their frequency and severity. Further research is needed to define the role of regional analgesic and anesthetic techniques in reducing postoperative pulmonary complications, and also to define the nature of risk factors and develop better predictive models of patients at risk of developing postoperative pulmonary complications.

Performance of a dose-defining insulin infusion protocol among trauma service intensive care unit admissions

BACKGROUND

Among critically ill patients, glycemic control reduces mortality and morbidities, but the use of intravenous insulin infusion is complicated by hypoglycemia. Having a standardized algorithm increases the likelihood of effective and safe utilization of intravenous insulin therapy. A tabular dose-defining protocol for intravenous insulin infusion is described, containing design elements intended to minimize risk for hypoglycemia while seeking control in a narrow target range, and performance is evaluated among critically ill trauma service patients.

METHODS

The protocol assigns insulin infusion rate (IR) for ranges of blood glucose (BG). The columns are arranged in order of increasing maintenance rate (MR) for insulin infusion. Patient column assignment is determined according to rate of change of BG. During stable column assignment, the IR is a function of column MR and BG. Within-column, the protocol formula provides that (a) for BG between 70 mg/dL and target BG, the IR increases exponentially to the column MR; and (b) for BG above upper target BG range, the IR increases linearly as an adaptation of the rule of 1800, with slope determined by the column MR. Values for IR calculated by formula are rounded to correspond to BG ranges of the table. Performance was assessed in 27 sequential runs among 24 trauma service patients admitted to a surgical intensive care unit (2004-2005).

RESULTS

Using point-of-care measurements, mean preinfusion BG was 230.0 +/- 67.9 mg/dL. BG < 140 mg/dL was reached during all 27 runs (median time 5.0 h), and target BG was < 110 mg/dL during 25 runs (median time 11.0 h). For the group of runs attaining target before interruption of insulin infusion, the average +/- SD of the principal measure of glycemic control, the within-run mean BG, was 113.7 +/- 14.8 mg/dL (coefficient of variation 13%, n = 25 runs). After attaining target, the average within-run SD for BG was 22.9 mg/dL. The within-run frequency of hypoglycemic measurements (BG < 70 mg/dL) as a percentage of BG determinations was 2.4%. In this series, no instance of BG <50 mg/dL was seen.

CONCLUSIONS

This report describes a nurse-implemented tabular protocol for intravenous insulin infusion having the advantages of efficacy, safety, and simplicity of use. Wide variability of IR in the neighborhood of BG 110 mg/dL is associated with stable BG response, and protection against hypoglycemia is achieved by rapid decline of IR at BGs in or below the target range.

A randomized trial of intermittent lorazepam versus propofol with daily interruption in mechanically ventilated patients

OBJECTIVE

To compare duration of mechanical ventilation for patients randomized to receive lorazepam by intermittent bolus administration vs. continuous infusions of propofol using protocols that include scheduled daily interruption of sedation.

DESIGN

A randomized open-label trial enrolling patients from October 2001 to March 2004.

SETTING

Medical intensive care units of two tertiary care medical centers.

PATIENTS

Adult patients expected to require mechanical ventilation for >48 hrs and who required > or =10 mg of lorazepam or a continuous infusion of a sedative to achieve adequate sedation.

INTERVENTIONS

Patients were randomized to receive lorazepam by intermittent bolus administration or propofol by continuous infusion to maintain a Ramsay score of 2-3. Sedation was interrupted on a daily basis for both groups.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was median ventilator days. Secondary outcomes included 28-day ventilator-free survival, intensive care unit and hospital length of stay, and hospital mortality. Median ventilator days were significantly lower in the daily interruption propofol group compared with the intermittent bolus lorazepam group (5.8 vs. 8.4, p = .04). The difference was largest for hospital survivors (4.4 vs. 9.0, p = .006). There was a trend toward greater ventilator-free survival for patients in the daily interruption propofol group (median 18.5 days for propofol vs. 10.2 for lorazepam, p = .06). Hospital mortality was not different.

CONCLUSIONS

For medical patients requiring >48 hrs of mechanical ventilation, sedation with propofol results in significantly fewer ventilator days compared with intermittent lorazepam when sedatives are interrupted daily.

Measurement of free and bound fractions of extracellular ATP in biological solutions using bioluminescence

Measurement of extracellular ATP in biological solutions is complicated by protein-binding and rapid enzymatic degradation. We hypothesized that the concentration of extracellular ATP could be determined luminometrically by limiting degradation and measuring the free and protein-bound fractions. ATP was added (a) at constant concentration to solutions containing varying albumin concentrations; (b) at varying concentrations to a physiological albumin solution (4 gm/dL); (c) at varying concentrations to plasma. After centrifugation, a fraction of each supernatant was heated. ATP in heated and unheated samples was measured luminometrically. Blood was drawn into saline or an ATP-stabilizing solution and endogenous plasma ATP measured. ATP-albumin binding was a linear function of albumin concentration (3.5% ATP bound at 100 micromol/L to 33.2% ATP bound at 1000 micromol/L) but independent of ATP concentration (29.3%, 10-1000 nmol/L ATP in 602 micromol/L albumin). Heating released the majority of bound ATP from albumin-containing solutions (94.8 +/- 1.7%) and plasma (97.6 +/- 5.1%). Total endogenous plasma ATP comprised 93 +/- 27 nmol/L (free) and 150 +/- 40 nmol/L (total fraction). Without stabilizing solution, degradation of free endogenous plasma ATP occurred. Within a physiological range (10-1000 nmol/L), ATP binds albumin independently of ATP concentration. Heating releases bound ATP, enabling accurate luminometric measurement of total extracellular ATP (free and bound) in biological samples.

Nucleotides induce IL-6 release from human airway epithelia via P2Y2 and p38 MAPK-dependent pathways

Extracellular nucleotides can mediate a variety of cellular functions via interactions with purinergic receptors. We previously showed that mechanical ventilation (MV) induces airway IL-6 and ATP release, modifies luminal nucleotide composition, and alters lung purinoceptor expression. Here we hypothesize that extracellular nucleotides induce secretion of IL-6 by small airway epithelial cells (SAEC). Human SAEC were stimulated with nucleotides in the presence or absence of inhibitors. Supernatants were analyzed for IL-6 and lysates for p38 MAPK activity by ELISA. RNA was analyzed by real-time RT-PCR. Rats (n=51) were randomized to groups as follows: control, small-volume MV, large-volume MV, large-volume MV-intratracheal apyrase, or small-volume MV-intratracheal adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS). After 1 h of MV, bronchoalveolar lavage fluid was analyzed for ATP and IL-6 by luminometry and ELISA. ATP and ATPgammaS increased SAEC IL-6 secretion in a time- and dose-dependent manner, an effect inhibited by apyrase. Agonists were ranked in the following order: ATPgammaS>ATP=UTP>ADP=adenosine>2-methylthio-ADP=control. SB-203580, but not U-0126 or JNK1 inhibitor, decreased nucleotide effects. Additionally, nucleotides induced p38 MAPK phosphorylation. Inhibitors of Ca2+ signaling, phospholipase C, transcription, and translation decreased IL-6 release. Furthermore, nucleotides increased IL-6 expression. In vivo, large-volume MV increased airway ATP and IL-6 concentrations. IL-6 release was decreased by apyrase and increased by ATPgammaS. Extracellular nucleotides induce P2Y2-mediated secretion of IL-6 by SAEC via Ca2+, phospholipase C, and p38 MAPK-dependent pathways. This effect is dependent on transcription and translation. Our findings were confirmed in an in vivo model, thus demonstrating a novel mechanism of nucleotide-induced IL-6 secretion by airway epithelia.

ATP stimulates MMP-2 release from human aortic smooth muscle cells via JNK signaling pathway

Aortic smooth muscle cell release of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) has been implicated in aortic aneurysm pathogenesis, but proximal modulation of release is poorly understood. Extracellular nucleotides regulate vascular smooth muscle cell metabolism in response to physiochemical stresses, but nucleotide modulation of MMP and/or TIMP release has not been reported. We hypothesized that nucleotides modulate MMP-2 and TIMP-2 release from human aortic smooth muscle cells (HASMCs) via distinct purinergic receptors and signaling pathways. We exposed HASMCs to exogenous ATP and other nucleotides with and without interleukin-1beta (IL-1beta). HASMCs were pretreated in some experiments with apyrase, which degrades ATP, and inhibitors of ERK1/2, JNK, and p38 MAPK. MMP-2 and TIMP-2 released into supernatant were assessed using ELISA and Western blotting. ATP, adenosine, and UTP significantly stimulated MMP-2 release in the presence of IL-1beta (300 nM ATP: 181 +/- 22%, P = 0.003; 30 microm adenosine: 244 +/- 150%, P = 0.001; and 200 microm UTP: 153 +/- 40%, P = 0.015; vs. 100% constitutive). ATP also stimulated MMP-2 release in the absence of IL-1beta (100 microm ATP: 148 +/- 38% vs. 100% constitutive). Apyrase significantly reduced ATP-stimulated MMP-2 release (apyrase + 500 nM ATP: 59 +/- 3% vs. 124 +/- 7% with 500 nM ATP). Rank-order agonist potency for MMP-2 release was consistent with ATP activation of PAY and PAY receptors. ATP induced phosphorylation of intracellular JNK, and inhibition of the JNK pathway blocked ATP-stimulated MMP-2 release, indicating signaling via this pathway. Nucleotides are thus novel stimulants of MMP-2 release from HASMCs and may provide a mechanistic link between physiochemical stress in the aorta and aneurysms, especially in the context of inflammation.

Superselective Catheterization and Embolization as First-Line Therapy for Lower Gastrointestinal Bleeding

Emergent operative intervention for lower gastrointestinal bleeding (LGIB) is associated with significant morbidity and mortality. Advances in endovascular techniques have made superselective catheterization and embolization (SSCE) of small visceral arterial branches possible. We hypothesized that SSCE for LGIB would be an effective first-line therapy and associated with low mortality. We identified all patients that underwent visceral angiography at our institution from 1997 to 2003. Records from all patients with documented LGIB and in whom SSCE was used as first-line therapy were reviewed. Twenty-three patients (69 ± 11 years) were treated with SSCE as an initial intervention for LGIB. A definitive bleeding site was identified in 95 per cent of cases (22/23). Eleven patients (48%) developed an early complication [recurrent bleeding (n = 5; two required surgery), asymptomatic ischemic colonic mucosa (n = 3), acute renal insufficiency (n = 1; resolved), and femoral pseudo-aneurysm (n = 2; one treated operatively)]. Long-term (mean 19 months) follow-up was available for 17 patients. Five patients (22%) experienced recurrent LGIB, and three patients had evidence of colonic ischemic. One patient required endoscopic dilation of a stricture, and three underwent surgical resection. There was no mortality in our series. In this series, SSCE was an effective first-line therapy for LGIB. Rebleeding and ischemia rates were low.

Superselective catheterization and embolization as first-line therapy for lower gastrointestinal bleeding

Emergent operative intervention for lower gastrointestinal bleeding (LGIB) is associated with significant morbidity and mortality. Advances in endovascular techniques have made superselective catheterization and embolization (SSCE) of small visceral arterial branches possible. We hypothesized that SSCE for LGIB would be an effective first-line therapy and associated with low mortality. We identified all patients that underwent visceral angiography at our institution from 1997 to 2003. Records from all patients with documented LGIB and in whom SSCE was used as first-line therapy were reviewed. Twenty-three patients (69 +/- 11 years) were treated with SSCE as an initial intervention for LGIB. A definitive bleeding site was identified in 95 per cent of cases (22/23). Eleven patients (48%) developed an early complication [recurrent bleeding (n=5; two required surgery), asymptomatic ischemic colonic mucosa (n=3), acute renal insufficiency (n=1; resolved), and femoral pseudo-aneurysm (n=2; one treated operatively)]. Long-term (mean 19 months) follow-up was available for 17 patients. Five patients (22%) experienced recurrent LGIB, and three patients had evidence of colonic ischemic. One patient required endoscopic dilation of a stricture, and three underwent surgical resection. There was no mortality in our series. In this series, SSCE was an effective first-line therapy for LGIB. Rebleeding and ischemia rates were low.

Blood transfusion is an independent predictor of increased mortality in nonoperatively managed blunt hepatic and splenic injuries

BACKGROUND

Management strategies for blunt solid viscus injuries often include blood transfusion. However, transfusion has previously been identified as an independent predictor of mortality in unselected trauma admissions. We hypothesized that transfusion would adversely affect mortality and outcome in patients presenting with blunt hepatic and splenic injuries after controlling for injury severity and degree of shock.

METHODS

We retrospectively reviewed records from all adults with blunt hepatic and/or splenic injuries admitted to a Level I trauma center over a 4-year period. Demographics, physiologic variables, injury severity, and amount of blood transfused were analyzed. Univariate and multivariate analysis with logistic and linear regression were used to identify predictors of mortality and outcome.

RESULTS

One hundred forty-three (45%) of 316 patients presenting with blunt hepatic and/or splenic injuries received blood transfusion within the first 24 hours. Two hundred thirty patients (72.8%) were selected for nonoperative management, of whom 75 (33%) required transfusion in the first 24 hours. Transfusion was an independent predictor of mortality in all patients (odds ratio [OR], 4.75; 95% confidence interval [CI], 1.37-16.4; p = 0.014) and in those managed nonoperatively (OR, 8.45; 95% CI, 1.95-36.53; p = 0.0043) after controlling for indices of shock and injury severity. The risk of death increased with each unit of packed red blood cells transfused (OR per unit, 1.16; 95% CI, 1.10-1.24; p < 0.0001). Blood transfusion was also an independent predictor of increased hospital length of stay (coefficient, 5.45; 95% CI, 1.64-9.25; p = 0.005).

CONCLUSION

Blood transfusion is a strong independent predictor of mortality and hospital length of stay in patients with blunt liver and spleen injuries after controlling for indices of shock and injury severity. Transfusion-associated mortality risk was highest in the subset of patients managed nonoperatively. Prospective examination of transfusion practices in treatment algorithms of blunt hepatic and splenic injuries is warranted.

Multidisciplinary approach to abdominal wall reconstruction after decompressive laparotomy for abdominal compartment syndrome

INTRODUCTION

Decompressive laparotomy for abdominal compartment syndrome has been shown to reduce mortality in critically ill patients, but little is known about the outcome of abdominal wall reconstruction. This study investigates the role of plastic surgeons in the management and reconstruction of these abdominal wall defects.

METHODS

We performed a retrospective review of 82 consecutive critically ill patients who underwent decompressive laparotomy for abdominal compartment syndrome, at a university level 1 trauma center, from April 2000 to May 2004. Patients reconstructed by trauma surgeons alone (n = 15) were compared with patients reconstructed jointly with plastic surgeons (n = 12), using Student t test and chi analysis.

RESULTS

Eighty-two patients underwent decompressive laparotomy for abdominal compartment syndrome, yielding 50 survivors (61%). Of the 27 patients who underwent abdominal wall reconstruction, 6 had early primary fascial repair, and 21 had staged reconstruction with primary fascial closure (n = 4), components separation alone (n = 3), components separation with mesh (n = 10), or permanent mesh only (n = 4). Compared with patients whose reconstruction was performed by trauma surgeons, patients who underwent a combined approach with plastic surgeons were older (50.5 versus 31.7 years, P < 0.05), had more comorbidities (P < 0.001), were less likely to have a traumatic etiology (P < 0.001), had a longer delay to reconstruction (407 versus 119 days, P < 0.05), and were more likely to undergo components separation (P < 0.05). Mean follow-up of 11.5 months revealed 2 recurrent hernias in the combined reconstruction group, both of which were successfully repaired.

CONCLUSIONS

A multidisciplinary approach is essential to the successful management of abdominal wall defects after decompressive laparotomy for abdominal compartment syndrome. Although carefully selected patients can undergo early primary fascial repair, most of reconstructed patients had staged closure of the abdominal wall via components separation, with a low rate of recurrent hernia. High-risk patients with large defects and comorbidities appear to benefit from the involvement of a plastic surgeon.

Intrapleural Tissue Plasminogen Activator for Complicated Pleural Effusions

BACKGROUND

This study is aimed at evaluating the safety and efficacy of intrapleural tissue plasminogen activator (TPA) for complicated pleural effusions, including posttraumatic hemothorax.

METHODS

Data were retrospectively collected from hospitalized patients over a 4-year period (1999-2003) who were treated with intrapleural TPA after failing drainage by tube thoracostomy. Pre- and post-TPA imaging studies were reviewed and scored by a blinded radiologist.

RESULTS

Forty-one consecutive patients with 42 effusions were identified with the following indications: 6 traumatic hemothoraces (14%), 22 loculated pleural effusions (52%), 2 line-associated hemothoraces (5%), and 12 empyemas (29%). Nine patients (22%) required operative drainage including two with posttraumatic hemothoraces. All patients managed nonoperatively demonstrated radiographic improvement after TPA administration. One patient (2.4%) developed hematuria, requiring transfusion. No trauma patient required TPA-related blood transfusion and no deaths were attributable to TPA therapy.

CONCLUSION

Intrapleural TPA administration appears safe for use in complicated pleural effusions and may decrease the need for operative intervention.

Mechanical ventilation alters airway nucleotides and purinoceptors in lung and extrapulmonary organs

Extracellular nucleotides are stress-responsive ligands that mediate a variety of cellular processes via purinoceptors. We hypothesized that mechanical ventilation (MV) would alter the extracellular adenyl-nucleotide profile and purinoceptor expression in lung and extrapulmonary tissues. Twenty-eight rats were randomized to: (i) unventilated control animals; (ii) tidal volume (VT; 6 ml/kg); (iii) VT (6 ml/kg) and positive end-expiratory pressure (PEEP; 5 cm H20); (iv) VT (12 ml/kg); or (v) VT (12 ml/kg) and PEEP (5 cm H20). Bronchoalveolar lavage (BAL) was analyzed for adenyl-nucleotides. Pulmonary, hepatic, and renal tissues were assessed for P2Y4, P2Y6, P2X7, A3, and A2b receptor expression by real-time reverse transcriptase-polymerase chain reaction and Fas/Fas ligand mRNA was quantified in the lung. MV produced volume-dependent changes in BAL nucleotides; AMP and adenosine increased, whereas ATP and ADP proportions decreased. Large-volume MV increased A2b mRNA and decreased P2X7 in the lung; mRNA changes in lung Fas ligand paralleled P2X7. PEEP normalized BAL nucleotide profiles and A2b expression. Injurious MV reduced hepatic and renal P2X7 mRNA; PEEP normalized these levels in both tissues. Large-volume MV also decreased renal A2b mRNA. MV alters the BAL adenyl-nucleotide profile and purinoceptor patterns in lung, liver, and kidney. PEEP normalizes the BAL nucleotide profile and receptor patterns in lung and extrapulmonary tissues.

Infrared thermography: a rapid, portable, and accurate technique to detect experimental pneumothorax

RATIONALE AND OBJECTIVE

Pneumothorax (Ptx) is a life-threatening complication that can result from trauma, mechanical ventilation, and invasive procedures. Infrared thermography (IRT), a compact and portable technology, has become highly sensitive. We hypothesized that IRT could detect Ptx by identifying associated changes in skin temperature.

MATERIALS AND METHODS

Bilateral nonpenetrating chest incisions or needle punctures were performed in 21 anesthetized rats. Rats were then randomized to no, bilateral, left, or right Ptx by either open (n = 16) or closed percutaneous (n = 5) puncture through selected pleurae. Real-time thermographic images and surface temperature data were acquired with a noncooled infrared camera.

RESULTS

In all cases, blinded observers correctly identified each Ptx with real-time grayscale image analysis. When compared to either the ipsilateral baseline or an abdominal reference, experimental Ptx produced a significantly greater decrease in surface temperature when compared to non-Ptx control.

CONCLUSIONS

These results demonstrate that portable infrared imaging can rapidly and accurately detect changes in thoracic surface temperature associated with experimental pneumothorax.

Adenosine triphosphate is released during injurious mechanical ventilation and contributes to lung edema

BACKGROUND

Extracellular nucleotides mediate many cellular functions and are released in response to mechanical stress in vitro. It is unknown whether adenosine triphosphate (ATP) is released in vivo during mechanical ventilation (MV). We hypothesized that stress from high-pressure MV would increase airway ATP, contributing to MV-associated lung edema.

METHODS

Rats were randomized to nonventilated control (n = 6) or 30 minutes of MV with low (15 cm H(2)0, n = 7) or high (40 cm H(2)0, n = 6) pressure. Additional groups received intratracheal ATP (n = 7) or saline (n = 7) before low-pressure MV.

RESULTS

Low-pressure MV did not affect lung edema or bronchoalveolar lavage (BAL) ATP levels. In contrast, high-pressure MV significantly increased BAL ATP and produced alveolar edema; lactate dehydrogenase was unchanged. Intratracheal ATP administration significantly increased lung water during low-pressure MV.

CONCLUSION

High-pressure MV increases BAL ATP concentration without altering lactate dehydrogenase, suggesting that release is not from cell lysis. Intratracheal ATP increases lung water, implicating nucleotides in MV-associated lung edema.

Effect of ventilatory rate on airway cytokine levels and lung injury

BACKGROUND

Controversy exists regarding the effect of large-volume mechanical ventilation (MV), as a sole stimulus, on the pulmonary cytokine milieu. We used a well described experimental model of ventilator-induced lung injury (VILI) to examine the impact of large volume ventilation on pulmonary cytokines in vivo and to study the effect of respiratory rate (RR) variation on these levels.

MATERIALS AND METHODS

Sixty rats (410 +/- 47 g) were randomized to: 1) non ventilated control; 2) V(t) = 40 ml/kg, RR = 40 bpm; 3) V(t) = 40 ml/kg, RR = 20 bpm; 4) V(t) = 7 ml/kg, RR = 40 bpm; or 5) V(t) = 7 ml/kg, RR = 20 bpm. After 1 h of MV, bronchoalveolar lavage (BAL) and serum were collected. BAL was analyzed for urea, protein, lactate dehydrogenase (LDH), tumor necrosis factor (TNF)alpha and interleukin (IL)-6. Epithelial lining fluid volume (ELF) was calculated.

RESULTS

Regardless of RR, animals ventilated at 7 ml/kg did not differ from control in any outcome. In contrast, MV at 40 ml/kg V(t) with 40 bpm produced lung injury characterized by significant elevations of BAL TNFalpha, IL-6, protein, ELF, and LDH. At 40 ml/kg V(t), RR reduction (20 bpm) significantly reduced all injury measures.

CONCLUSION

This study confirms that large-volume MV, as a sole stimulus, produces lung injury and cytokine release. Whereas increasing RR at low V(t) has little impact on injury parameters, RR reduction under VILI-promoting conditions significantly limits lung injury.

Partial liquid ventilation and positive end-expiratory pressure reduce ventilator-induced lung injury in an ovine model of acute respiratory failure

OBJECTIVE

To examine the isolated and combined effects of positive end-expiratory pressure (PEEP) and partial liquid ventilation (PLV) on the development of ventilator-induced lung injury in an ovine model.

DESIGN

Prospective controlled animal study.

SETTING

University-based cardiovascular animal physiology laboratory.

SUBJECTS

Thirty-eight anesthetized supine sheep weighing 22.3 +/- 2.2 kg.

INTERVENTIONS

Animals were ventilated for 6 hrs (respiratory rate, 15; FIO2, 1.0, inspiratory/expiratory ratio, 1:1) with one of five pressure-controlled strategies, expressed as peak inspiratory pressure (PIP)/PEEP: low-PIP, 25/5 cm H2O (n = 8); high-PIP, 50/5 cm H2O (n = 8); high-PIP-PLV, 50/5 cm H2O-PLV (n = 8); high-PEEP, 50/20 cm H2O (n = 7); and high-PEEP-PLV, 50/20 cm H2O-PLV (n = 7).

MEASUREMENTS AND MAIN RESULTS

Compared with the low-PIP control, high-PIP ventilation increased airleak, shunt, histologic evidence of lung injury, neutrophil infiltrates, and wet lung weight. Maintaining PEEP at 20 cm H2O or adding PLV reduced the development of physiologic shunt and dependent histologic injury indexes. Neither higher PEEP nor PLV reduced the high incidence of barotrauma observed in high-PIP animals.

CONCLUSIONS

We conclude that application of PLV or PEEP at 20 cm H2O may improve gas exchange and afford lung protection from ventilator-induced lung injury during high-pressure mechanical ventilation in this model.

A novel stable reproducible model of hepatic failure in canines

BACKGROUND

Stable and reproducible large animal models of hepatic failure, which allow the assessment of liver-assist devices, are not available. Our objective was to develop a physiologically stable animal model of hepatic failure on which the safety and efficacy of an extracorporeal liver-assist device can be tested. We hypothesized that a surgical model which consists of an end-to-side portocaval shunt combined with common bile duct ligation and transection would create hepatic failure with: (1) elevations in amino transferases, total bilirubin, and ammonia; (2) a decrease in the ratio of branched chain to aromatic amino acids; and (3) histologic evidence of hepatic injury.

METHODS

Eleven mongrel dogs underwent common bile duct transection and an end-to-side portocaval shunt. Aminotransferases (AST, ALT), total bilirubin, ammonia, and branched chain and aromatic amino acids were measured prior to operation (baseline) and after 9 days. A necropsy was performed on Postoperative Day 9 and liver biopsies were obtained for histology.

RESULTS

By Postoperative Day 9, AST, ALT, total bilirubin, and ammonia values were significantly elevated compared to baseline (P < 0.02). The ratio of branched chain to aromatic amino acids was significantly reduced compared to baseline (P < 0.003). There was histologic evidence of cholestasis and inflammation.

CONCLUSION

Portocaval shunt with common bile duct transection produces liver failure with elevations in aminotransferases, total bilirubin, and ammonia, a decreased branched chain to aromatic amino acid ratio, and histologic inflammation. Unlike ischemic or chemically induced models of liver failure, the dogs were hemodynamically and neurologically stable. This model can be used to test the safety and efficacy of liver-assist devices aimed at temporizing the detoxification functions of the failing liver.

Effect of rate and inspiratory flow on ventilator-induced lung injury

BACKGROUND

We examined the effects of decreasing respiratory rate (RR) at variable inspiratory times (It) and reducing inspiratory flow on the development of ventilator-induced lung injury.

METHODS

Forty sheep weighing 24.6+/-3.2 kg were ventilated for 6 hours with one of five strategies (FIO2 = 1.0, positive end-expiratory pressure = 5 cm H2O): (1) pressure-controlled ventilation (PCV), RR = 15 breaths/min, peak inspiratory pressure (PIP) = 25 cm H2O, n = 8; (2) PCV, RR = 15 breaths/min, PIP = 50 cm H2O, n = 8; (3) PCV, RR = 5 breaths/min, PIP = 50 cm H2O, It = 6 seconds, n = 8; (4) PCV, RR = 5 breaths/min, PIP = 50 cm H2O, It = 2 seconds, n = 8; and (5) limited inspiratory flow volume-controlled ventilation, RR = 5 breaths/min, pressure-limit = 50 cm H2O, flow = 15 L/min, n = 8.

RESULTS

Decreasing RR at conventional flows did not reduce injury. However, limiting inspiratory flow rate (LIFR) maintained compliance and resulted in lower Qs/Qt (HiPIP = 38+/-18%, LIFR = 19+/-6%, p < 0.001), reduced histologic injury (HiPIP = 14+/-0.9, LIFR = 2.2+/-0.9, p < 0.05), decreased intra-alveolar neutrophils (HiPIP = 90+/-49, LIFR = 7.6+/-3.8,p = 0.001), and reduced wet-dry lung weight (HiPIP = 87.3+/-8.5%, LIFR = 40.8+/-17.4%,p < 0.001).

CONCLUSIONS

High-pressure ventilation for 6 hours using conventional flow patterns produces severe lung injury, irrespective of RR or It. Reduction of inspiratory flow at similar PIP provides pulmonary protection.

Prolonged partial liquid ventilation in spontaneously breathing awake animals

OBJECTIVE

To date, studies of partial liquid ventilation (PLV) have examined its effects acutely in anesthetized and mechanically ventilated subjects. We set out to develop a model of prolonged PLV in awake, spontaneously breathing animals.

DESIGN

Animal case series

SETTING

Cardiopulmonary physiology laboratory.

SUBJECTS

Fifteen New Zealand white rabbits (3.2+/-0.39 kg).

INTERVENTIONS

Animals were anesthetized and instrumented with a novel technique allowing percutaneously assisted placement of an intratracheal catheter with a subcutaneously tunneled externalized free end. After anesthetic recovery, PLV was performed in spontaneously breathing unsedated animals.

MEASUREMENTS AND MAIN RESULTS

Evaporative losses were determined using a single 10 mL/kg perflubron dose (n = 5); hourly radiographs were obtained until residual perflubron was minimal. For prolonged PLV (n = 10), a 10-mL/kg initial perflubron dose was followed every 4 hrs with 5-mL/kg supplements. Radiographs were obtained immediately before and after perflubron administration and were scored (0-5) by a radiologist blinded to dosing regimen and time interval. Data were analyzed with ANOVA and Student's t-test with correction for multiple comparisons. Initial filling was nearly complete (score = 4.8+/-0.42); lungs were maintained approximately half-filled through 4 hrs (score = 2.53+/-0.71). By 6 hrs, the majority of perflubron had evaporated (score = 1.75+/-0.53). Over 24 hrs, radiographs documented continuous perflubron exposure (postffill = 4.53+/-0.64, prefill = 3.40+/-0.71, average = 3.97+/-0.43); scores were comparatively higher after filling (after = 4.53+/-0.64, before = 3.4+/-0.71, p< .001). Left and right lung volumes were equivalent (left = 4.06+/-0.47, right = 3.89+/-0.39, p = .027). All animals survived the 24 hrs of PLV.

CONCLUSIONS

Percutaneously assisted intratracheal cannulation with catheter exteriorization permits prolonged PLV in spontaneously breathing, unsedated animals. Continuous perfluorocarbon exposure with this method is reproducible, consistent, and well tolerated for 24 hrs in uninjured animals.

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.

Can the clearance of tumor necrosis factor alpha and interleukin 6 be enhanced using an albumin dialysate hemodiafiltration system?

Patients with acute hepatic failure (AHF) have elevated levels of inflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6). Recently, we have shown selective hemodiafiltration with albumin dialysis, as an extracorporeal liver support device (ECLVS), to be effective in the clearance of multiple toxins that are elevated in AHF. Our objective was to evaluate whether ECLVS would be effective in the clearance of TNF-alpha and IL-6. An in vitro continuous hemodiafiltration circuit was used with single pass counter-current dialysis. A known amount of recombinant rat TNF-alpha and IL-6 was added to heparinized bovine blood and filtered across a polyalkyl sulfone hemofilter using matched filtration and dialysate flow rates. During 4 hours, the serial TNF-alpha and IL-6 concentrations were measured in the circulating blood, and the content of each cytokine was calculated using mass balance. For each cytokine, clearance was determined for two dialysate groups at constant temperature and pH (group 1: dialysate = 0.9 normal saline, n = 5; group 2: dialysate = albumin 2 gm/dl, n = 5). Analysis of data was performed using ANOVA and Student's t-test. There was improved clearance of TNF-alpha and IL-6 when albumin was used in the dialysate (81+/-0.09% of the initial TNF-alpha and 77+/-0.04% of the IL-6 quantities) compared with when 0.9 normal saline was used as the dialysate (58+/-0.14% of the initial TNF-alpha and 56+/-0.18% of the IL-6 quantities); p < 0.03. An ECLVS utilizing hemodiafiltration with albumin dialysis is more effective than conventional hemofiltration in the clearance of TNF-alpha and IL-6 and, therefore, may benefit patients with acute hepatic failure.

A prospective comparison of atrio-femoral and femoro-atrial flow in adult venovenous extracorporeal life support

INTRODUCTION

In the United States, venovenous extracorporeal life support has traditionally been performed with atrial drainage and femoral reinfusion (atrio-femoral flow). Although flow reversal (femoro-atrial flow) may alter recirculation and extracorporeal flow, no direct comparison of these 2 modes has been undertaken.

OBJECTIVE

Our goal was to prospectively compare atrio-femoral and femoro-atrial flow in adult venovenous extracorporeal life support for respiratory failure.

METHODS

A modified bridge enabling conversion between atrio-femoral and femoro-atrial flow was incorporated in the extracorporeal circuit. Bypass was initiated in the direction that provided the highest pulmonary arterial mixed venous oxygen saturation, and the following measurements were taken: (1) maximum extracorporeal flow, (2) highest achievable pulmonary arterial mixed venous oxygen saturation, and (3) flow required to maintain the same pulmonary arterial mixed venous oxygen saturation in both directions. Flow direction was then reversed, and the measurements were repeated. Data were compared with paired t tests and are presented as mean +/- standard deviation.

RESULTS

Ten patients were studied, and 9 were included in the data analysis. Femoro-atrial bypass provided (1) higher maximal extracorporeal flow (femoro-atrial flow = 55.6 +/- 9.8 mL/kg per minute, atrio-femoral flow = 51.1 +/- 11.1 mL/kg per minute; P = .04) and (2) higher pulmonary arterial mixed venous oxygen saturation (femoroatrial flow = 89.9% +/- 6.6%, atrio-femoral flow = 83.2% +/- 4.2%; P = .006); (3) furthermore, it required less flow to maintain an equivalent pulmonary arterial mixed venous oxygen saturation (femoro-atrial flow = 37.0 +/- 12.2 mL/kg per minute, atrio-femoral flow = 46.4 +/- 8.8 mL/kg per minute; P = .04).

CONCLUSIONS

During venovenous extracorporeal life support, femoro-atrial bypass provided higher maximal extracorporeal flow, higher pulmonary arterial mixed venous oxygen saturation, and required comparatively less flow to maintain an equivalent mixed venous oxygen saturation than did atrio-femoral bypass.

Use of extracorporeal life support for adult patients with respiratory failure and sepsis

Traditionally, adult sepsis has been considered a contraindication to extracorporeal life support (ECLS). The objective of this study was to review the authors' institutional experience with a subgroup of adult patients requiring ECLS for severe respiratory failure and sepsis. Hospital records from 100 consecutive adult patients with respiratory failure placed on ECLS between 1990 and 1996 were retrospectively reviewed. Patients with sepsis as a primary indication were identified, and blood culture data reviewed. Data were analyzed with t tests and chi-square and are presented as mean +/- standard deviation. Multiple logistic regression determined the impact of sepsis and positive blood cultures (PBCs) on survival. Fourteen patients required ECLS for sepsis; 36 had PBCs during hospitalization (15 before or during ECLS). Septic patients had lower pre-ECLS PaO2/FIO2 ratios (septic: 53 +/- 14 mmHg, nonseptic: 70 +/- 68 mmHg, p = 0.04). Patients with PBCs before or during ECLS were younger (PBC: 29 +/- 6 years, no PBC: 35 +/- 13 years, p = 0.003), remained on ECLS longer (PBC: 485 +/- 336 hours, no PBC: 232 +/- 212 hours, p = 0.01), and were more frequently cannulated within 12 hours (PBC: 15/15, no PBC 60/85 p = 0.02). Neither group differed in organ dysfunction (incidence or type), frequency of respiratory recovery, or survival. Neither sepsis nor positive blood cultures were independently predictive of mortality. Sepsis and positive blood cultures do not adversely affect outcome in adult patients with respiratory failure requiring ECLS.

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.

Extracorporeal life support for 100 adult patients with severe respiratory failure

OBJECTIVE

The authors retrospectively reviewed their experience with extracorporeal life support (ECLS) in 100 adult patients with severe respiratory failure (ARF) to define techniques, characterize its efficacy and utilization, and determine predictors of outcome.

SUMMARY BACKGROUND DATA

Extracorporeal life support maintains gas exchange during ARF, providing diseased lungs an optimal environment in which to heal. Extracorporeal life support has been successful in the treatment of respiratory failure in infants and children. In 1990, the authors instituted a standardized protocol for treatment of severe ARF in adults, which included ECLS when less invasive methods failed.

METHODS

From January 1990 to July 1996, the authors used ECLS for 100 adults with severe acute hypoxemic respiratory failure (n = 94): paO2/FiO2 ratio of 55.7+/-15.9, transpulmonary shunt (Qs/Qt) of 52+/-22%, or acute hypercarbic respiratory failure (n = 6): paCO2 84.0+/-31.5 mmHg, despite and after maximal conventional ventilation. The technique included venovenous percutaneous access, lung "rest," transport on ECLS, minimal anticoagulation, hemofiltration, and optimal systemic oxygen delivery.

RESULTS

Overall hospital survival was 54%. The duration of ECLS was 271.9+/-248.6 hours. Primary diagnoses included pneumonia (49 cases, 53% survived), adult respiratory distress syndrome (45 cases, 51 % survived), and airway support (6 cases, 83% survived). Multivariate logistic regression modeling identified the following pre-ECLS variables significant independent predictors of outcome: 1) pre-ECLS days of mechanical ventilation (p = 0.0003), 2) pre-ECLS paO2/FiO2 ratio (p = 0.002), and 3) age (years) (p = 0.005). Modeling of variables during ECLS showed that no mechanical complications were independent predictors of outcome, and the only patient-related complications associated with outcome were the presence of renal failure (p < 0.0001) and significant surgical site bleeding (p = 0.0005).

CONCLUSIONS

Extracorporeal life support provides life support for ARF in adults, allowing time for injured lungs to recover. In 100 patients selected for high mortality risk despite and after optimal conventional treatment, 54% survived. Extracorporeal life support is extraordinary but reasonable treatment in severe adult respiratory failure. Predictors of survival exist that may be useful for patient prognostication and design of future prospective studies.

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 degrees C, n = 5; pH = 7.5, temperature = 20 degrees C, n = 5; pH = 7.0, temperature = 40 degrees 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.