Respiratory failure and sepsis are the major causes of ICU admissions and mortality in survivors of lung transplants

Infections in Heart and Lung Transplant Recipients

Infections in heart and lung transplant recipients are complex and heterogeneous. This article reviews the epidemiology, risk factors, specific clinical syndromes, and most frequent opportunistic infections in heart and/or lung transplant recipients that will be encountered in the intensive care unit and will provide a practical approach of empirical management.

Low HDL-Cholesterol Concentrations in Lung Transplant Candidates are Strongly Associated With One-Year Mortality After Lung Transplantation

High-density lipoproteins (HDLs), whose main role is the reverse transport of cholesterol, also have pleiotropic anti-inflammatory, antioxidant, anti-apoptotic and anti-infectious properties. During sepsis, HDL cholesterol (HDL-C) concentration is low, HDL particle functionality is altered, and these modifications are correlated with poor outcomes. Based on the protective effects of HDL, we hypothesized that HDL-C levels could be associated with lung transplantation (LT) outcome. We thus looked for an association between basal HDL-C concentration and one-year mortality after LT. In this single-center prospective study including consecutive LTs from 2015 to 2020, 215 patients were included, essentially pulmonary fibrosis (47%) and chronic obstructive pulmonary disease (COPD) (38%) patients. Mortality rate at one-year was 23%. Basal HDL-C concentration stratified nonsurvivors to survivors at one-year (HDL-C = 1.26 [1.12-1.62] mmol/L vs. HDL-C = 1.55 [1.22-1.97] mmol/L, p = 0.006). Multivariate analysis confirmed that HDL-C concentration during the pretransplant assessment period was the only variable inversely associated with mortality. Moreover, mortality at one-year in patients with HDL-C concentrations ≤1.45 mmol/L was significantly higher (log-rank test, p = 0.00085). In conclusion, low basal HDL-C concentrations in candidates for LT are strongly associated with mortality after LT. To better understand this association, further studies in this field are essential and, in particular, a better characterization of HDL particles seems necessary.

Gram-negative bacteremia in solid organ transplant recipients: Clinical characteristics and outcomes as compared to immunocompetent non-transplant recipients

BACKGROUND

Outcomes from Gram-negative bacteremia (GNB) in solid organ transplant (SOT) recipients are poorly understood.

METHODS

This is a single center prospective cohort study comparing the clinical characteristics and outcomes of SOT recipients with GNB to immunocompetent non-SOT patients with GNB between 1/1/2002 through 12/31/2018. Outcomes of interest included incidence of septic shock, respiratory failure, and time to death. A multivariable logistic regression model was used to determine factors associated with incidence of septic shock and respiratory failure. Time to death was evaluated using Cox proportional hazard models.

RESULTS

A total of 297 SOT and 1245 immunocompetent non-SOT patients were included. Incidence of septic shock did not significantly differ between the groups (SOT 25.3% vs. non-SOT 24.6%, p = .8225). Overall survival did not significantly differ by transplant status (30-day survival: SOT 76%, 95% confidence interval [CI] 70, 92, non-SOT 74%, 95% CI 71, 77: log rank: p = .76). SOT recipients taking three immunosuppressive medications had significantly lower odds of developing septic shock or respiratory failure requiring intubation and mechanical ventilation than those taking ≤1 agent (shock: adjusted odds ratio [aOR] 0.29, 95% CI 0.09, 0.90, p = .0316; respiratory failure: aOR 0.14, 95% CI: 0.04, 0.49, p = .0020).

CONCLUSIONS

SOT recipients with GNB do not experience higher rates of septic shock, respiratory failure, or mortality than immnon-SOT recipients with GNB. Among SOT recipients, a greater number of immunosuppressive medications may be associated with improved outcomes during GNB. Future studies are needed to understand the potential relationship between levels of immunosuppression and clinical outcome in SOT recipients with GNB.

Using Machine Learning to Develop and Validate an In-Hospital Mortality Prediction Model for Patients with Suspected Sepsis

Background: Early recognition of sepsis and the prediction of mortality in patients with infection are important. This multi-center, ED-based study aimed to develop and validate a 28-day mortality prediction model for patients with infection using various machine learning (ML) algorithms. Methods: Patients with acute infection requiring intravenous antibiotic treatment during the first 24 h of admission were prospectively recruited. Patient demographics, comorbidities, clinical signs and symptoms, laboratory test data, selected sepsis-related novel biomarkers, and 28-day mortality were collected and divided into training (70%) and testing (30%) datasets. Logistic regression and seven ML algorithms were used to develop the prediction models. The area under the receiver operating characteristic curve (AUROC) was used to compare different models. Results: A total of 555 patients were recruited with a full panel of biomarker tests. Among them, 18% fulfilled Sepsis-3 criteria, with a 28-day mortality rate of 8%. The wrapper algorithm selected 30 features, including disease severity scores, biochemical parameters, and conventional and few sepsis-related biomarkers. Random forest outperformed other ML models (AUROC: 0.96; 95% confidence interval: 0.93–0.98) and SOFA and early warning scores (AUROC: 0.64–0.84) in the prediction of 28-day mortality in patients with infection. Additionally, random forest remained the best-performing model, with an AUROC of 0.95 (95% CI: 0.91–0.98, p = 0.725) after removing five sepsis-related novel biomarkers. Conclusions: Our results demonstrated that ML models provide a more accurate prediction of 28-day mortality with an enhanced ability in dealing with multi-dimensional data than the logistic regression model.

Intensive care readmissions in the first year after lung transplantation: Incidence, early risk factors and outcome

BACKGROUND

Predictive factors of intensive care readmissions after lung transplantation (LT) have not been established. The main objective of this study was to assess early risk factors for ICU readmission during the first year after LT.

METHODS

This retrospective, observational, single-centre study included all consecutive patients who underwent LT in our institution between January 2016 and November 2019. Patients who died during the initial hospitalisation in the ICU were excluded. Surgical and medical ICU readmissions were collected during the first year. The results are expressed as medians, interquartile ranges, absolute numbers and percentages. Statistical analyses were performed using the chi-square test, Fisher's exact test and Mann-Whitney U test as appropriate (p < 0.05 as significance). Multivariate analysis was performed to identify independent risk factors for readmission. The Paris-North-Hospitals Institutional Review Board reviewed and approved the study.

RESULTS

A total of 156 patients were analysed. Eighteen of them (12%) died during the initial ICU hospitalisation. During the first year after LT, ICU readmission was observed for 49/138 (36%) patients. Among these patients, 14/49 (29%) died during the study period. Readmission was mainly related to respiratory failure (35 (71%) patients), infectious diseases (28 (57%) patients), airway complications (11 (22%) patients), and immunologic complications (4 (8%) patients). In the multivariate analysis, ICU readmission was associated with the use of high doses of catecholamines during surgery, and the increased duration of initial ICU stay.

CONCLUSION

The initial severity of haemodynamic failure and a prolonged postoperative course seem to be key determinants of ICU readmissions after LT.

Pneumonia versus graft dysfunction as the cause of acute respiratory failure after lung transplant: a 4-year multicentre prospective study in 153 adults requiring intensive care admission

We aimed to assess the main causes of intensive care unit (ICU) readmissions in lung transplant adults and to identify independent predictors of ICU mortality (primary end-point).This Spanish five-centre prospective cohort study enrolled all lung transplant adults with ICU readmissions after post-transplant ICU discharge between 2012 and 2016. Patients were followed until hospital discharge or death.153 lung transplant recipients presented 174 ICU readmissions at a median (interquartile range) of 6 (2-25) months post-transplant. Chronic lung allograft dysfunction was reported in 39 (25.5%) recipients, 13 of whom (all exitus) had restrictive allograft syndrome (RAS). Acute respiratory failure (ARF) (110 (71.9%)) was the main condition requiring ICU readmission. Graft rejection (six (5.4%) acute) caused only 12 (10.8%) readmissions whereas pneumonia (56 (36.6%)) was the main cause (50 admitted for ARF and six for shock), with Pseudomonas aeruginosa (50% multidrug resistant) being the predominant pathogen. 55 (35.9%) and 69 (45.1%) recipients died in the ICU and the hospital, respectively. Bronchiolitis obliterans syndrome (BOS) stage 2 (adjusted OR (aOR) 7.2 (95% CI 1.0-65.7)), BOS stage 3 (aOR 13.7 (95% CI 2.5-95.3)), RAS (aOR >50) and pneumonia at ICU readmission (aOR 2.5 (95% CI 1.0-7.1)) were identified in multivariate analyses as independent predictors of ICU mortality. Only eight (5.2%) patients had positive donor-specific antibodies prior to ICU readmission and this variable did not affect the model.ARF was the main condition requiring ICU readmission in lung transplant recipients and was associated with high mortality. Pneumonia was the main cause of death and was also an independent predictor. RAS should receive palliative care rather than ICU admission.

Infections in Heart and Lung Transplant Recipients

Infections in heart and lung transplant recipients are complex and heterogeneous. This article reviews the epidemiology, risk factors, specific clinical syndromes, and most frequent opportunistic infections in heart and/or lung transplant recipients that will be encountered in the intensive care unit and will provide a practical approach of empirical management.

Influence of early neurological complications on clinical outcome following lung transplant

Background

Neurological complications after lung transplantation are common. The full spectrum of neurological complications and their impact on clinical outcomes has not been extensively studied.

Methods

We investigated the neurological incidence of complications, categorized according to whether they affected the central, peripheral or autonomic nervous systems, in a series of 109 patients undergoing lung transplantation at our center between January 1 2013 and December 31 2014.

Results

Fifty-one patients (46.8%) presented at least one neurological complication. Critical illness polyneuropathy-myopathy (31 cases) and phrenic nerve injury (26 cases) were the two most prevalent complications. These two neuromuscular complications lengthened hospital stays by a median period of 35.5 and 32.5 days respectively. However, neurological complications did not affect patients’ survival.

Conclusions

The real incidence of neurological complications among lung transplant recipients is probably underestimated. They usually appear in the first two months after surgery. Despite not affecting mortality, they do affect the mean length of hospital stay, and especially the time spent in the Intensive Care Unit. We found no risk factor for neurological complications except for long operating times, ischemic time and need for transfusion. It is necessary to develop programs for the prevention and early recognition of these complications, and the prevention of their precipitant and risk factors.

Timing and Frequency of Unplanned Readmissions After Lung Transplantation Impact Long-Term Survival

BACKGROUND

Adverse events that require hospital readmission frequently occur long after lung transplantation (LT) that has been successfully performed. We sought to identify the causes and rate of unplanned readmissions after LT and to determine whether unplanned readmissions have a significant impact on post-LT survival.

METHODS

We retrospectively reviewed the outcomes in 174 LT recipients who underwent LT at our center from June 2005 to May 2014. The median follow-up period was 38 months (range, 17 to 72 months).

RESULTS

One hundred sixty (92%) of the 174 recipients were readmitted 854 times (5.3 times per patient). The median time to first readmission was 71 days (interquartile range [IQR], 28 to 240 days), and the median hospital length of stay at readmission was 3 days (IQR, 2 to 6 days). Freedom from first readmission was observed for 65% of patients at 1 month, 48% at 3 months, 43% at 6 months, and 26% at 12 months. Gender, lung allocation score, body surface area, year of transplantation, air leak longer than 5 days after operation, and allograft function were risk factors for readmission. The causes of readmission included infections (33%), respiratory adverse events (18%), rejection (15%), gastrointestinal events (15%), renal dysfunction (5%), and cardiac events (4%). Patients who died were found to have had early readmissions (p = 0.04) and more frequent readmissions (p = 0.001).

CONCLUSIONS

The first year after LT remains a high-risk period for unplanned readmissions regardless of pretransplantation diagnosis. Readmissions soon after discharge at index hospitalization and multiple readmissions are associated with an increased risk of mortality.

Humidified high flow nasal cannula supportive therapy improves outcomes in lung transplant recipients readmitted to the intensive care unit because of acute respiratory failure

BACKGROUND

The effectiveness of humidified high flow nasal cannula (HFNC) in lung transplant (LTx) recipients readmitted to intensive care unit (ICU) because of acute respiratory failure (ARF) has not been determined to date.

METHODS

Retrospective analysis of a prospectively assessed cohort of LTx patients who were readmitted to ICU because of ARF over a 5-year period. Patients received conventional oxygen therapy (COT) or HFNC (Optiflow, Fisher & Paykel, New Zealand) supportive therapy according to the attending physician's criteria. Treatment failure was defined as the need for subsequent mechanical ventilation (MV).

RESULTS

Thirty-seven LTx recipients required ICU readmission, with a total of 40 episodes (18 COT vs. 22 HFNC). At ICU admission, no differences in comorbidities, pulmonary function, or median sequential organ failure assessment (COT, 4 [interquartile range, 4-6] vs. HFNC, 4 [interquartile range, 4-7]; P = 0.51) were observed. Relative risk of MV in patients with COT was 1.50 (95% confidence interval [95% CI], 1.02-2.21). The absolute risk reduction for MV with HFNC was 29.8%, and the number of patients needed to treat to prevent one intubation with HFNC was 3. Multivariate analysis showed that HFNC therapy was the only variable at ICU admission associated with a decreased risk of MV (odds ratio, 0.11 [95% CI, 0.02-0.69]; P = 0.02). Moreover, nonventilated patients had an increased survival rate (20.7% vs. 100%; relative rate 4.83 [95% CI, 2.37-9.86]; P < 0.001). No adverse events were associated with HFNC use.

CONCLUSION

HFNC O2 therapy is feasible and safe and may decrease the need for MV in LTx recipients readmitted to the ICU because of ARF.

Factors affecting discharge destination following lung transplantation

BACKGROUND

Lung transplant (LT) recipients requiring additional care may be referred to inpatient rehabilitation prior to discharge home. This study seeks to describe discharge destinations following LT, compare the characteristics of patients discharged to different destinations, and identify the predictors of discharge destination.

METHODS

Retrospective study of 243 LT recipients who survived to hospital discharge between 2006 and 2009. LT recipients were compared based on discharge destination on data pertaining to demographics, clinical characteristics, and healthcare utilization.

RESULTS

Of the 243 recipients, 197 (81%) were discharged home, 42 (17%) to inpatient rehabilitation, and 4 (2%) to other medical facilities. Age, pulmonary diagnosis, most recent six-minute walk distance (6 MWD) prior to transplant, pre-transplant mechanical ventilation, priority listing status, pre- and post-transplant intensive care unit length of stay (ICU LOS), post-transplant LOS, total LOS, and participation in pre-transplant rehabilitation were statistically different between patients that were discharged home versus inpatient rehabilitation. Age, most recent 6 MWD prior to transplant, pre-transplant mechanical ventilation, and total LOS were found to be independent predictors of discharge destination.

CONCLUSION

Clinical factors can help identify patients more likely to require inpatient rehabilitation. Identification of these factors has the potential to facilitate early discharge planning and optimize continuity of care.

Invasive diagnostic strategies in immunosuppressed patients with acute respiratory distress syndrome

Immunosuppression predisposes the host to development of pulmonary infections, which can lead to respiratory failure and the development of acute respiratory distress syndrome (ARDS). There are multiple mechanisms by which a host can be immunosuppressed and each is associated with specific infectious pathogens. Early invasive diagnostic modalities such as fiber-optic bronchoscopy with bronchoalveolar lavage, transbronchial biopsy, and open lung biopsy are complementary to serologic and noninvasive studies and assist in rapidly establishing an accurate diagnosis, which allows initiation of appropriate therapy and may improve outcomes with relative safety.

Resveratrol reduces acute lung injury in a LPS‑induced sepsis mouse model via activation of Sirt1

The development of acute lung injury (ALI) during sepsis almost doubles the mortality rate of patients. The efficacy of current treatment strategies is low as treatment is usually initiated following the onset of symptoms. Inflammation is one of the main mechanisms of autoimmune disorders and is a common feature of sepsis. The suppression of inflammation is therefore an important mechanism for the treatment of sepsis. Sirtuin 1 (Sirt1) has been demonstrated to play a role in the regulation of inflammation. Resveratrol, a potent Sirt1 activator, exhibits anti‑inflammatory properties. However, the role of resveratrol for the treatment of ALI during sepsis is not fully understood. In the present study, the anti‑inflammatory role of Sirt1 in the lipopolysaccharide (LPS)‑induced TC‑1 cell line and its therapeutic role in ALI was investigated in a mouse model of sepsis. The upregulation of matrix metalloproteinase-9, interleukin (IL)‑1β, IL‑6 and inducible nitric oxide synthase was induced by LPS in the mouse model of sepsis and the TC‑1 cell line, and resveratrol suppressed the overexpression of these proinflammatory molecules in a dose‑dependent manner. Resveratrol decreased pulmonary edema in the mouse model of sepsis induced by LPS. In addition, resveratrol improved lung function and reduced pathological alterations in the mouse model of sepsis. Knockdown of Sirt1 by RNA interference resulted in an increased susceptibility of TC‑1 cells to LPS stimulation and diminished the anti‑inflammatory effect of resveratrol. These results demonstrated that resveratrol inhibits LPS‑induced ALI and inflammation via Sirt1, and indicated that Sirt1 is an efficient target for the regulation of LPS‑induced ALI and inflammation. The present study provides insights into the treatment of ALI during sepsis.

Impact of nutritional state on lung transplant outcomes

BACKGROUND

When high-risk lung transplant candidates are evaluated, nutritional state is often neglected. We evaluated the prevalence of markers reflecting pre-transplant malnutrition and their association with post-operative complications and death.

METHODS

From January 2005 to July 2010, 453 patients underwent primary lung transplantation at our institution. Pre-operative nutrition-related variables, including body mass index and weight/height ratio, reflecting cachexia, and albumin, total protein, immunoglobulins, and absolute lymphocyte count were considered in identifying risk factors for time-related major post-operative complications (renal failure requiring dialysis, respiratory failure requiring tracheostomy), pulmonary or bloodstream infections, and death.

RESULTS

Forty-eight patients had BMI <18.5 kg/m(2), 41 had a weight/height ratio ≤ 0.3, 102 had albumin <3.5 g/dl, 110 had total protein <6 g/dl, and 112 had an absolute lymphocyte count <1,000/μl, indicative of a malnourished state. At 6 months, 30% had experienced pulmonary infection, with lower total serum protein concentration an important risk (p = 0.02). One-year actuarial mortality was 15%; risk factors included lower serum albumin (p = 0.004), particularly when <3 g/dl. In contrast, variables reflecting nutritional state were not statistically significantly correlated with dialysis, respiratory failure requiring tracheostomy, or bloodstream infections.

CONCLUSION

Although malnutrition is uncommon in lung transplant patients, those at extremes of low serum albumin and total protein have worse survival and increased risk of post-operative infection. Strategies to improve nutrition of these high-risk candidates awaiting lung transplantation should be developed.

Prognosis Factors in Lung Transplant Recipients Readmitted to the Intensive Care Unit

OBJECTIVE

To identify outcome predictors and prognostic factors for survival among lung transplant recipients on readmission to the intensive care unit (ICU).

METHODS

This was a retrospective study of all lung transplant recipients during a 10-year period from 1997 to 2006. Data collection included age, gender, reason, and type of lung transplantation. Variables specific to individual ICU admissions included admission diagnosis, length of stay, duration of mechanical ventilation, interval from transplantation, Acute Physiology and Chronic Health Evaluation (APACHE) II score on ICU admission, and the identification of systemic organ dysfunction. We used Student t test (or where appropriate, its nonparametric equivalent) or the chi(2) test for comparisons among the patients who died and those who survived their ICU readmissions.

RESULTS

Among 144 lung transplant patients 28 were later readmitted to the ICU after at least 1 week. The admission diagnosis was sepsis in 20 cases (71.4%). Seventeen patients died during their ICU stay (60.7%). A higher APACHE II score (P = .008), the presence of three or more dysfunctional organs upon readmission (P = .016), and the need for mechanical ventilation (P = .022) were risk factors for mortality. The mortality risk was also higher among the group with a longer delay to ICU readmission (P = .003).

DISCUSSION

Readmission to the ICU, which is common among lung transplant recipients, was associated with a high mortality. Sepsis was the main cause of ICU readmission and the most frequent cause of death. APACHE II score, need for mechanical ventilation, number of dysfunctional organs, and delay in ICU readmission were important prognostic factors.

Bacteremia in lung transplant recipients in the current era

Current trends in the epidemiology, outcome and variables influencing mortality in bacteremic lung transplant recipients have not been fully described. We prospectively studied bacteremias in lung transplant recipients in a multicenter study between 2000-2004. Bacteremia was documented in 56 lung transplant recipients, an average of 172 days after transplantation. Multiple antibiotic resistance was documented in 48% of the isolates; these included 57% of the Gram-negative and 38% of the Gram-positive bacteria. Pulmonary infection was the most common source of resistant gram-negative bacteremias. Mortality rate at 28 days after the onset of bacteremia was 25% (14/56). Mechanical ventilation and abnormal mental status correlated independently with higher mortality (p < 0.05 for both variables). Bacteremia remains a significant complication in lung transplant recipients and is associated with considerable mortality. Recognition of variables portending a high risk for antibiotic resistance and for poor outcome has implications relevant for optimizing antibiotic prescription and for improving outcomes in lung transplant recipients.

Update of early respiratory failure in the lung transplant recipient

PURPOSE OF REVIEW

Respiratory failure remains the most common complication in the perioperative period after lung transplantation. Consequently it is important to develop an approach to diagnosis and the treatment of respiratory failure in this population. This review highlights the advances made in the understanding and treatment of lung transplant patients in the early postoperative phase. Owing to its relative importance, advances in the understanding and treatment of ischaemia-reperfusion injury are highlighted.

RECENT FINDINGS

The causes of respiratory failure and the complications seen after transplantation are time dependent, with ischaemia-reperfusion, infection, technical problems and acute rejection being the most common in the early perioperative phase, and obliterative bronchiolitis, rejection, and infections secondary to bacteria, fungi, and viruses becoming more prevalent after 3 months. The advances in lung preservation and postoperative care may be overshadowed by an increase in the complexity of the recipients and the use of more marginal organs. An improved mechanistic understanding of ischaemia-reperfusion injury has translated into potential therapeutic targets. The development of prospective clinical trials, however, is hampered by a relatively small sample of patients and a significant degree of heterogeneity in the lung transplant population.

SUMMARY

Many advances have been made in the understanding of ischaemia-reperfusion injury. Owing to the acute and long-term implications of this complication, interventions that reduce the risk of developing ischaemia-reperfusion need to be evaluated in prospective clinical trials.

Admission Hyperglycemia and Other Risk Factors as Predictors of Hospital Mortality in a Medical ICU Population

BACKGROUND

Tight glycemic control is recommended for patients in the ICU, as hyperglycemia is associated with increased morbidity and mortality.

DESIGN

Observational cohort of patients admitted to a 12-bed, inner-city, medical ICU (MICU).

SUBJECTS

A total of 1,185 of 1,506 patients from July 1, 1999, to December 31, 2002, selected based on a diagnosis other than diabetic ketoacidosis or glycemia > 280 mg/dL or < 80 mg/dL.

PURPOSES

To determine if the highest serum glucose level within 24 h after ICU admission is associated with increased hospital mortality when adjusted for confounders.

MEASUREMENTS

Age, gender, race, worst values within 24 h after ICU admission to construct the acute physiology and chronic health evaluation (APACHE) II score, and highest glucose within 24 h after ICU admission. Hospital mortality was the primary outcome. Admitting diagnosis, MICU length of stay (LOS), and hospital LOS were obtained. Glucose, albumin (n = 867), and lactic acid (n = 319) were stratified for analysis.

ANALYSIS

Univariate analysis identified factors included in the multivariate model.

RESULTS

Patients were predominantly African-American (79%) and men (56%; mean age, 49.2 years). The mean ICU admission highest glucose level was 139 +/- 43.7 mg/dL (+/- SD). MICU LOS and hospital LOS were 6.2 days and 12.9 days, respectively, and 50% of patients received mechanical ventilation. MICU and hospital mortality were 18% and 20%, respectively; standardized mortality ratio was 66%. On univariate analysis, survivors (n = 945) and nonsurvivors (n = 240) showed APACHE II score, mechanical ventilation, hypoalbuminemia, lactic acidemia, and logistic organ dysfunction system score to be hospital mortality predictors; however, the highest admission serum glucose level was not. Logistic regression estimated APACHE II score/per point (odds ratio, 1.06; 95% confidence interval, 1.02 to 1.11), mechanical ventilation (odds ratio, 3.06; 95% confidence interval, 1.34 to 6.96), severe hypoalbuminemia (< 2 g/dL) [odds ratio, 2.98; 95% confidence interval, 1.3 to 7.02], and severe lactic acidemia (> or = 8 mmol/L) [odds ratio, 7.3; 95% confidence interval, 2.14 to 24.9], but not ICU admission hyperglycemia, to be associated with hospital mortality.

CONCLUSIONS

Conventional factors of disease severity, but not highest glucose value during the first 24 h after ICU admission, predict hospital mortality in an inner-city MICU.

Endotoxin-induced lung injury in mice: structural, functional, and biochemical responses

Acute lung injury is usually a complication of sepsis, and endotoxin treatment of mice is a frequently used experimental model. To define this model and to clarify pathogenesis of the lung injury, we injected with 1 mg/kg endotoxin ip and measured pulmonary function, pulmonary edema, serum concentrations of cytokines and growth factors, and lung histology over 48 h. During the first 6 h, tidal volume and minute volume increased and respiratory frequency decreased. Serum concentrations of cytokines showed three patterns: 10 cytokines peaked at 2 h and declined rapidly, two peaked at 6 h and declined, and two had biphasic peaks at 2 and 24 h. Growth factors increased later and remained elevated longer. Both collagen and fibronectin were deposited in the lungs beginning within hours of endotoxin and resolving over 48 h. Histologically, lungs showed increased cellularity at 6 h with minimal persistent inflammation at 48 h. Lung water peaked at 6 h and gradually decreased over 48 h. We conclude that intraperitoneal administration of endotoxin to mice causes a transient systemic inflammatory response and transient lung injury and dysfunction. The response is characterized by successive waves of cytokine release into the circulation, early evidence of lung fibrogenesis, and prolonged increases in growth factors that may participate in lung repair.

Outcome of Lung Transplant Patients Admitted to the Medical ICU

INTRODUCTION

Lung transplantation is an acceptable treatment option for end-stage lung disease. Short-term survival has improved, but lung transplant recipients remain at high risk for a variety of complications that can necessitate care in an ICU. Little is known about the epidemiology, clinical outcomes, and risk factors for survival among lung transplant recipients admitted to the ICU.

METHODS

All lung transplant recipients at a single institution discharged from the hospital after their transplant and subsequently admitted to the medical ICU (MICU) between March 1, 1999, and February 28, 2001, were included. Patients were followed until death or February 28, 2002. Demographic data collected included transplant type and date, APACHE (acute physiology and chronic health evaluation) III scores, last preadmission and best posttransplant FEV(1) in liters, admitting diagnosis, use of mechanical ventilation, and previous MICU admission.

RESULTS

There were 51 patients admitted to the MICU during the study period (73 total admissions). Their demographic data, pretransplant diagnoses, and type of transplant were similar to those of the rest of Duke University Medical Center lung transplant patients. Fifty-three percent (27 of 51 patients) required mechanical ventilation during their first MICU admission. Thirty-seven percent (19 of 51 patients) died during their first MICU admission. Fifty-nine percent (16 of 27 patients) receiving mechanical ventilation died. Patients who died had lower FEV(1) to posttransplant best FEV(1) ratio prior to MICU admission, and also had higher APACHE III scores on MICU admission compared to survivors: FEV(1), 51.3 +/- 21.9% (n = 14) vs 75.5 +/- 20.4% (n = 30) [p = 0.001]; APACHE III score, 77.7 +/- 21.4 (n = 19) vs 60.1 +/- 16.5 (n = 32) [p = 0.002]. Survival rates by Kaplan-Meier analysis at 1 year and 2 years after initial MICU admission were 43.1% and 40.9%, respectively. The longest survivor is currently alive 1,087 days after initial MICU admission.

CONCLUSION

Admission to the MICU is common in lung transplant recipients. MICU care, including mechanical ventilation, is associated with a poor prognosis in lung transplant recipients, but is appropriate for selected patients with good allograft function.