Ventilator-associated pneumonia in burn patients: a cause or consequence of critical illness?

Severity of Inhalation Injury and Risk of Nosocomial Pneumonia: A Retrospective Cohort Study

BACKGROUND

The impact of inhalation injury on risk of nosocomial pneumonia (NP), an important complication in patients with burns, is not well established.

RESEARCH QUESTION

Is more severe inhalation injury associated with increased risk of NP?

STUDY DESIGN AND METHODS

We performed a retrospective cohort study of patients with suspected inhalation injury admitted to a regional burn center from 2011 to 2022 who underwent diagnostic bronchoscopy within 48 h of admission. We estimated the association of high-grade inhalation injury (Abbreviated Injury Scale score 3 and 4) vs low-grade inhalation injury (Abbreviated Injury Scale score 1 and 2) with NP adjusted for age, burn size, and comorbid obstructive lung disease. Death and hospital discharge were considered competing risks.

RESULTS

Of the 245 patients analyzed, 51 (21%) had high-grade injury, 180 (73%) had low-grade injury, and 14 (6%) had no inhalation injury. Among the 236 patients hospitalized for ≥ 48 h, NP occurred in 24 of 50 patients (48%) in the high-grade group, 54 of 172 patients (31%) in the low-grade group, and two of 14 patients (14%) in the no inhalation injury group. High-grade (vs low-grade) inhalation injury was associated with higher hazard of NP in both the proportional cause-specific hazard model (cause-specific hazard ratio, 2.04; 95% CI, 1.26-3.30; P = .004) and Fine-Gray subdistribution hazard model (subdistribution hazard ratio for NP, 2.24; 95% CI, 1.38-3.64; P = .001).

INTERPRETATION

Among patients with inhalation injury, more severe injury was associated with higher hazard of NP in competing risk analysis. Additional research is needed to investigate mechanisms that may explain the relationship between inhalation injury and NP and to identify more effective risk reduction strategies.

Geriatric Burn Injuries Presenting to the Emergency Department of a Major Burn Center: Clinical Characteristics and Outcomes

BACKGROUND

Burn injuries in geriatric patients are common and may have significant associated morbidity and mortality. Most research has focused on the care of hospitalized patients after admission to burn units. Little is known about the clinical characteristics of geriatric burn victims who present to the emergency department (ED) and their ED assessment and management.

OBJECTIVE

Our aim was to describe the clinical characteristics and outcomes of geriatric patients presenting to the ED with burn injuries.

METHODS

We performed a comprehensive retrospective chart review on all patients 60 years and older with a burn injury presenting from January 2011 through September 2015 to a large, urban, academic ED in a hospital with a 20-bed burn center.

RESULTS

A total of 459 patients 60 years and older were treated for burn injuries during the study period. Median age of burn patients was 71 years, 23.7% were 80 years and older, and 56.6% were female. The most common burn types were hot water scalds (43.6%) and flame burns (23.1%). Median burn size was 3% total body surface area (TBSA), 17.1% had burns > 10% TBSA, and 7.8% of patients had inhalation injuries. After initial evaluation, 46.4% of patients were discharged from the ED. Among patients discharged from the ED, only 1.9% were re-admitted for any reason within 30 days. Of the patients intubated in the ED, 7.1% were extubated during the first 2 days of admission, and 64.3% contracted ventilator-associated pneumonia.

CONCLUSIONS

Better understanding of ED care for geriatric burn injuries may identify areas in which to improve emergency care for these vulnerable patients.

Detection of Infection and Sepsis in Burns

Background: Infection is the most frequent complication after severe burns and has a propensity to progress into sepsis then septic shock and multiple organ dysfunction syndrome (MODS). Improving outcomes in acute burn care depends on early detection of infection to allow prompt interventions. Diagnosis of sepsis in severe burns is uniquely challenging because otherwise-typical clinical signs are masked by the hypermetabolic state and systemic inflammation induced by the burn itself. For this reason, burns have historically been excluded from high-impact studies on the diagnosis and treatment of sepsis. Methods: This article provides a comprehensive three-fold review of current findings and guidelines pertinent to the early detection of infection and sepsis in severe burns. Results: First, evidence-based detection of the most common infections encountered in the burn intensive care unit is reviewed. Second, we analyze the evolution of the diagnostic criteria for sepsis and the evidence regarding their utility in severe burns. Last, we examine the development of biomarkers, from procalcitonin to molecular genomics, for the detection of sepsis. Conclusions: Although gold standard methods of early detection of sepsis in burn patients have yet to be identified, improved understanding and appropriate application of the available diagnostic criteria and assays are paramount to providing effective care of patients with severe burns.

Inhalation injury is associated with long-term employment outcomes in the burn population: Findings from a cross-sectional examination of the Burn Model System National Database

Introduction

Inhalation injuries carry significant acute care burden including prolonged ventilator days and length of stay. However, few studies have examined post-acute outcomes of inhalation injury survivors. This study compares the long-term outcomes of burn survivors with and without inhalation injury.

Methods

Data collected by the Burn Model System National Database from 1993 to 2019 were analyzed. Demographic and clinical characteristics for adult burn survivors with and without inhalation injury were examined. Outcomes included employment status, Short Form-12/Veterans Rand-12 Physical Composite Score (SF-12/VR-12 PCS), Short Form-12/Veterans Rand-12 Mental Composite Score (SF-12/VR-12 MCS), and Satisfaction With Life Scale (SWLS) at 24 months post-injury. Regression models were used to assess the impacts of sociodemographic and clinical covariates on long-term outcome measures. All models controlled for demographic and clinical characteristics.

Results

Data from 1,871 individuals were analyzed (208 with inhalation injury; 1,663 without inhalation injury). The inhalation injury population had a median age of 40.1 years, 68.8% were male, and 69% were White, non-Hispanic. Individuals that sustained an inhalation injury had larger burn size, more operations, and longer lengths of hospital stay (p<0.001). Individuals with inhalation injury were less likely to be employed at 24 months post-injury compared to survivors without inhalation injury (OR = 0.63, p = 0.028). There were no significant differences in PCS, MCS, or SWLS scores between groups in adjusted regression analyses.

Conclusions

Burn survivors with inhalation injury were significantly less likely to be employed at 24 months post-injury compared to survivors without inhalation injury. However, other health-related quality of life outcomes were similar between groups. This study suggests distinct long-term outcomes in adult burn survivors with inhalation injury which may inform future resource allocation and treatment paradigms.

Intubation in burns patients: a 5-year review of the Manchester regional burns centre experience

Despite criteria to guide intubation from the American Burn Association (ABA), concerns remain regarding over-intubation of burns patients. The purpose of this study was to review appropriateness of intubation at a UK regional burns centre over a 5-year period. A 5-year retrospective review of adult patients admitted to the Manchester Burns Centre who underwent intubation at or prior to admission was performed. Intubations for non-burn indications or burns >40%TBSA were excluded. Patient demographic and burn characteristics data were extracted from medical records. Indications for intubation were compared to ABA and Denver criteria. 47 patients were identified, of which 40 met inclusion criteria for analysis. 72.5% and 95% of these patients met ABA or Denver criteria respectively. 30.8% of patients were extubated within 48 h. 50% patients extubated within 48 h had ≤1 indication for intubation or negative laryngoscopy. Complications related to intubation and ventilation were noted in 37.5% of patients, with ventilation associated pneumonia (VAP) being the most common occurring in 27.5%. 95% of patients fulfilled recognised criteria for intubation. However, 30% were extubated within 48 h, suggesting potentially avoidable intubation. This study suggests current intubation criteria may over-estimate risk of airway compromise and supports results from non-UK studies that a proportion of patients may be suitable for close observation rather than early intubation.

Bacterial Virulence Factors and Their Contribution to Pathophysiology after Thermal Injury

Background: Bacterial infections are the leading cause of morbidity and mortality in burn-injured patients. Pseudomonas aeruginosa and Staphylococcus aureus are among the most common pathogens responsible for infections in thermally injured patients. These and other pathogens have developed a variety of virulence factors to colonize and infect hosts. Methods: A comprehensive literature review was conducted to best summarize the current knowledge of how virulence factors contribute to bacterial pathogenicity. Results: The review highlights the unique mechanisms bacteria utilize to evade host defense systems and further complicate the treatment of burn-injured patients. Conclusion: Further research on virulence factors and their contribution to bacterial pathogenicity is warranted and could potentially lead to development of neutralizing pharmacotherapy that would complement antimicrobial treatment.

Defining the criteria for intubation of the patient with thermal burns

OBJECTIVES

Recent studies demonstrate that burn patients are undergoing unnecessary intubations. We sought to determine the clinical criteria that predict intubations with benefit.

METHODS

This was a retrospective review of intubated adults admitted to our center with thermal burns 2008-2013. Criteria for intubation were defined as traditional criteria (suspected smoke inhalation, oropharynx soot, hoarseness, dysphagia, singed facial hair, oral edema, oral burn, non-full thickness facial burns), or ABA criteria as defined by the 2011 ABA guidelines (full thickness facial burns, stridor, respiratory distress, swelling on laryngoscopy, upper airway trauma, altered mentation, hypoxia/hypercarbia, hemodynamic instability). Patients with <26days free from mechanical ventilation (ventilator-free days (VFD)) out of 28, were deemed indicated long-term intubations. Those with ≥26 VFD were deemed unnecessary short-term intubations.

RESULTS

Of 218 patients, 151 had long-term and 67 had short-term intubations. Long-term intubation was strongly associated with ABA criteria (77.5%) compared to traditional criteria (22.5%) (p<0.001). Sensitivity of ABA criteria for long-term intubation was 77% and specificity 46%. Traditional criteria associated with long-term intubation included suspected smoke inhalation (OR 2.45 [95% CI, 1.18-5.11]), and singed facial hair (OR 2.53 [95% CI, 1.25-5.09]). The addition of these to ABA criteria created the Denver criteria, which exhibited an increased sensitivity for long-term intubations (95%), but decreased specificity (24%).

CONCLUSIONS

Intubation should be considered for patients displaying the Denver criteria, which includes full thickness facial burns, stridor, respiratory distress, swelling on laryngoscopy, upper airway trauma, altered mentation, hypoxia/hypercarbia, hemodynamic instability, suspected smoke inhalation, and singed facial hair. Patients lacking these criteria should not be intubated.

Ventilator-Associated Pneumonia Prevention Bundle Significantly Reduces the Risk of Ventilator-Associated Pneumonia in Critically Ill Burn Patients

Ventilator-associated pneumonia (VAP) is a common cause of morbidity and mortality for critically ill burn patients. Prevention of VAP through bundled preventative measures may reduce the risk and incidence of VAP in burn patients. A retrospective chart review was performed of all mechanically ventilated adult (age ≥ 18 years) burn patients before and after VAP prevention bundle implementation. Data collected included age, TBSA, gender, diagnosis of inhalation injury, mechanism of injury, comorbid illnesses, length of mechanical ventilation, length of hospital stay, development of VAP, discharge disposition, and mortality. Burn patients with VAP had larger burn injuries (47.6 ± 22.2 vs 23.9 ± 23.01), more inhalation injuries (44.6% vs 27%), prolonged mechanical ventilation, and longer intensive care unit (ICU) and hospital stays. Mortality was also higher in burn patients who developed VAP (34% vs 19%). On multivariate regression analysis, TBSA and ventilator days were independent risk factors for VAP. In 2010, a VAP prevention bundle was implemented in the burn ICU and overseen by a nurse champion. Compliance with bundle implementation was more than 95%. By 2012, independent of age, TBSA, inhalation injury, ventilator days, ICU and hospital length of stay, VAP prevention bundles resulted in a significantly reduced risk of developing VAP (odds ratio of 0.15). Burn patients with an inhalation injury and a large burn injury are at increased risk of developing VAP. The incidence and risk of VAP can be significantly reduced in burn patients with VAP prevention bundles.

Reducing the Indication for Ventilatory Support in the Severely Burned Patient: Results of a New Protocol Approach at a Regional Burn Center

Initial management of the severely injured routinely includes sedation and mechanical ventilatory support. However, nonjudiciously applied mechanical ventilatory support can itself lead to poorer patient outcomes. In an attempt to reduce this iatrogenic risk, a standardized, in-house, five-point protocol providing clinical guidance on the use and duration of ventilation was introduced and analyzed, and the impact on patient outcomes was assessed. In 2007, a protocol for early spontaneous breathing was introduced and established in clinical practice. This protocol included: 1) early extubation (≤6 hours after admission) in the absence of absolute ventilatory indication; 2) avoidance of "routine intubation" in spontaneously breathing patients; 3) early postoperative extubation, including patients requiring multiple surgical interventions; 4) intensive chest and respiratory physiotherapy with routine application of expectorants; and 5) early active mobilization. A retrospective clinical study compared patients (group A) over a 2-year period admitted under the new protocol with a historical patient group (group B). Patients in group A (n = 38) had fewer ventilator days over the time-course of treatment (3 [1; 5.8] vs 18.5 days [0.5; 20.5]; P = .0001) with a lower rate of tracheostomies (15.8 vs 54%; P = .0003). Patients on ventilation at admission in group A had shorter ventilation periods after admission (4.75 [4; 22.25] vs 378 hours [8.5; 681.5]; P = .0003), and 66.7% of these patients were extubated within 6 hours of admission (vs 9.1% in group B). No patients fulfilling the inclusion criteria required re- or emergency intubation. In the first 5 days of treatment, significantly lower Sequential Organ Failure Assessment scores were recorded in group A. There was also a trend for lower mortality rates (0 [0%] vs 6 [14%]), sepsis rates (24 [63.2%] vs 37 [88.1%]), and cumulative fluid balance on days 3 and 7 in group A. In contrast, group A demonstrated an elevated rate of pneumonia (15 [39.5%] vs 8 [19%]). These trends, however, lacked statistical significance. Our five-point protocol was safe and easily translated into clinical practice. In the authors experience, this protocol significantly reduced the ventilatory period in severely injured. Furthermore, this study suggests that many injured may be over-treated with routine ventilation, which carries accompanying risks.

Laryngeal Trauma Following an Inhalation Injury: A Review and Case Report

The primary concern when managing a patient with inhalation injury is security of the airway. Airflow may be impeded by both edema of the upper airway and reduction of oxygen delivery to the lower respiratory tract. Although there has been much discussion regarding management of the latter, the focus of this article is the management of the former. This review aimed to determine the optimum management in burn victims with upper airway inhalation injury as an attempt to prevent laryngeal trauma leading to long-term voice disorders and upper airway dyspnea. We describe the case of a 57-year-old woman with significant inhalation injury and discuss the natural progression of her injuries and the laryngeal controversies surrounding her care. We conclude with advice on the optimal management of this condition based on our experience, combined with current best evidence.

Fluid resuscitation mediates the association between inhalational burn injury and acute kidney injury in the major burn population

BACKGROUND

It is known that acute respiratory distress syndrome and acute lung injury are independent risk factors for developing acute kidney injury (AKI) through complex pathophysiologic mechanisms. Our specific aim is to evaluate the risk factors for AKI postburn injury and whether inhalation thermal injury is an independent risk factor for developing AKI in the major burn population.

METHODS

This is an institutional review board-approved, retrospective cohort study of patients admitted to a tertiary burn intensive care unit between 2011 and 2013. We included adults (age 18 years or older) with major burn injury greater than or equal to 20% total burn surface area (TBSA) and patients with confirmed inhalation injury (±major burn). Acute kidney injury was defined using the acute kidney injury network serum creatinine criteria up to 5 days after admission. Patient demographics and clinical data were compared across cohorts using the Wilcoxon rank sum test or Pearson χ² test, as appropriate. Multiple logistic regression was used to assess the effect of inhalation injury and major burn on the incidence of AKI, adjusting for clinical and demographic confounders.

RESULTS

Two hundred fifty-four patient records (90 with inhalation injury and 164 with major burn only) were evaluated. The mean age on admission was 47±19 years and 72% of the cohort were men. There were more men in the major burn group (78% vs 62%; P=.007). No other significant differences were observed in the baseline demographics. The overall incidence of AKI was 28% (95% confidence interval, 22, 33). The unadjusted odds of AKI were nearly double (odds ratio, 1.99; 95% confidence interval, 1.13, 3.49) among those with inhalation injury relative to those with major burn only. However, there was no evidence of an independent inhalational injury effect after adjusting for potential confounders. In particular, TBSA (P=.051), daily 24-hour fluid balance (P<.001), and most recent 24-hour albumin transfusion status (P=.002) were all significantly associated with AKI in the adjusted analysis. Age and packed red blood cell transfusion status were not significant.

CONCLUSION

Inhalation thermal injury is not an independent risk factor for AKI after adjusting for TBSA and surrogates for fluid resuscitation. In patients with major burns, intensity of fluid resuscitation may mediate the development of AKI.

Surveillance of antibiotic susceptibility in a Swedish Burn Center 1994-2012

Patients with burn trauma are at risk for infections caused by antibiotic resistant bacteria (ABR) with subsequent increase in morbidity and mortality. As part of the Swedish strategic program against antibiotic resistance in intensive care (ICU-Strama), we have surveyed the distribution of species and ABR in isolates from patients admitted to a Swedish burn center at Linköping University Hospital from 1994 through 2012. In an international comparison Strama has been successful in reducing the antibiotic consumption among animals and humans in primary care. The aim of this study was to investigate the antibiotic consumption pressure and resistance rates in a Swedish burn unit.

METHODS

Microbiology data, total body surface area (TBSA), patient days, and mortality were collected from a hospital database for all patients admitted to the Burn Center at the University Hospital of Linköping from April 1994 through December 2012.

RESULTS

A total of 1570 patients were admitted with a mean annual admission rate of 83 patients (range: 57-152). 15,006 microbiology cultures (approximately 10 per patient) were collected during the study period and of these 4531 were positive (approximately 3 per patient). The annual mean total body surface area (TBSA) was 13.4% (range 9.5-18.5) with an annual mortality rate of 5.4% (range 1-8%). The MRSA incidence was 1.7% (15/866) which corresponds to an MRSA incidence of 0.34/1000 admission days (TAD). Corresponding figures were for Escherichia coli resistant to 3(rd) generation cephalosporins (ESBL phenotype) 8% (13/170) and 0.3/TAD, Klebsiella spp. ESBL phenotype 5% (6/134) and 0.14/TAD, carbapenem resistant Pseudomonas aeruginosa 26% (56/209) and 1.28/TAD, and carbapenem resistant Acinetobacter spp. 3% (2/64) and 0.04/TAD.

CONCLUSIONS

Our results show a sustained low risk for MRSA and high, although not increasing, risk for carbapenem resistant P. aeruginosa.

Incidence of ventilator associated pneumonia in burn patients with inhalation injury treated with high frequency percussive ventilation versus volume control ventilation: A systematic review

BACKGROUND

Pneumonia increases mortality in burn patients with inhalation injuries. We evaluated whether the use of High Frequency Percussive Ventilation (HFPV) in burn patients with inhalation injuries can decrease rates of Ventilator Associated Pneumonia (VAP) compared to Volume Control Ventilation (VCV).

METHODS

Data were gathered from PubMed, EMBASE, Web of Science, reference lists, and hand search. For unpublished data we searched ClinicalTrials.gov and RePORTER. We included observational and Randomized Controlled Trials (RCTs) that compared rates of VAP with the use of HFPV and VCV in adult burn patients with inhalation injury. Two reviewers independently extracted data from the retrieved studies and assessed them for eligibility, methodology, and quality.

RESULTS

281 abstracts were reviewed, of which 4 studies (540 patients) were included. Two were observational and two were RCTs. All studies had moderate risk of bias. One study had low external validity while others had moderate external validity. The two observational studies found non-concordant results. One study found a 24% statistically significant reduction in the rates of VAP while the other found no difference. The two RCTs had small sample sizes. There was no significant difference in VAP rates between HFPV and VCV. The VCV arms of the four studies were heterogeneous. Only one study used low tidal volumes, whereas the rest used high tidal volumes in the VCV arm.

CONCLUSION

Evidence about decreased incidence of VAP in burn patients with inhalation injuries who are on HFPV compared to those on VCV is inconclusive. Although enhanced airway clearance by HFPV was thought to play a role in decreasing VAP in this population, high tidal volume in the VCV arms could be a confounding factor that should be eliminated in future studies before a firm conclusion can be reached. More RCTs comparing HFPV to low tidal volume VCV are needed.

Interpretation for practice guidelines for prevention, diagnosis, and treatment of ventilator-associated pneumonia in burn patients by american burn association

“American Burn Association Practice Guidelines for Prevention, Diagnosis, and Treatment of Ventilator-Associated Pneumonia in Burn Patients” was published to provide recommendation for the prevention, diagnosis, and treatment of ventilator-associated pneumonia in burn patients. This article makes interpretations and conclusions for prevention, diagnosis and treatment from this guideline in the combination of domestic burn patients.

Outcomes of a ventilator-associated pneumonia bundle on rates of ventilator-associated pneumonia and other health care-associated infections in a long-term acute care hospital setting

Long-term trends in ventilator-associated pneumonia (VAP) rates, and other health care-associated infections, were examined prior to, during, and after introduction of a VAP bundle in a long-term acute care hospital setting. VAP incidence rate declined in a step-wise fashion and reached a null value. Incidence rates of bacteremia from any cause declined in a similar fashion. The incidence rates of vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus colonization or infection rates also decreased, but that of Clostridium difficile infection did not. VAP in the long-term acute care hospital setting can be controlled over time with implementation of Centers for Disease Control and Prevention-based VAP bundle. This outcome also may decrease certain other health care-associated infections.