Closing the "care in the air" capability gap for severe lung injury: the Landstuhl Acute Lung Rescue Team and extracorporeal lung support.

BACKGROUND: The success of US Air Force Critical Care Air Transport Teams (CCATT) in transporting critically ill and injured patients enabled changes in military medical force deployment and casualty care practice. Even so, a subset of casualties remains who exceed even CCATT capabilities for movement. These patients led to the creation of the Landstuhl Acute Lung Rescue Team (ALeRT) to close the "care in the air" capability gap. METHODS: The ALeRT Registry was queried for the period between November 1, 2005, and June 30, 2010. Additionally, Landstuhl Regional Medical Center critical care patient transfers to host nation medical centers were reviewed for cases using extracorporeal lung support systems. RESULTS: For the review period, US Central Command activated the ALeRT on 40 occasions. The ALeRT successfully evacuated patients on 24 of 27 missions launched (89%). Three patients were too unstable for ALeRT evacuation. Of the 13 remaining activations, four patients died and nine patients improved sufficiently for standard CCATT movement. The ALeRT initiated pumpless extracorporeal lung assistance six times, but only once to facilitate evacuation. Two patients were supported with full extracorporeal membrane oxygenation support after evacuation due to progressive respiratory failure. CONCLUSIONS: ALeRT successfully transported 24 casualties from the combat zones to Germany. Without the ALeRT, these patients would have remained in the combat theater as significant consumers of limited deployed medical resources. Pumpless extracorporeal lung assistance is already within the ALeRT armamentarium, but has only been used for one aeromedical evacuation. Modern extracorporeal membrane oxygenation systems hold promise as a feasible capability for aeromedical evacuation.

High-frequency percussive ventilation and low tidal volume ventilation in burns: a randomized controlled trial.

OBJECTIVES: In select burn intensive care units, high-frequency percussive ventilation is preferentially used to provide mechanical ventilation in support of patients with acute lung injury, acute respiratory distress syndrome, and inhalation injury. However, we found an absence of prospective studies comparing high-frequency percussive ventilation with contemporary low-tidal volume ventilation strategies. The purpose of this study was to prospectively compare the two ventilator modalities in a burn intensive care unit setting. DESIGN: Single-center, prospective, randomized, controlled clinical trial, comparing high-frequency percussive ventilation with low-tidal volume ventilation in patients admitted to our burn intensive care unit with respiratory failure. SETTING: A 16-bed burn intensive care unit at a tertiary military teaching hospital. PATIENTS: Adult patients ≥ 18 yrs of age requiring prolonged (> 24 hrs) mechanical ventilation were admitted to the burn intensive care unit. The study was conducted over a 3-yr period between April 2006 and May 2009. This trial was registered with ClinicalTrials.gov as NCT00351741. INTERVENTIONS: Subjects were randomly assigned to receive mechanical ventilation through a high-frequency percussive ventilation-based strategy (n = 31) or a low-tidal volume ventilation-based strategy (n = 31). MEASUREMENTS AND MAIN RESULTS: At baseline, both the high-frequency percussive ventilation group and the low-tidal volume ventilation group had similar demographics to include median age (interquartile range) (28 yrs [23-45] vs. 33 yrs [24-46], p = nonsignificant), percentage of total body surface area burn (34 [20-52] vs. 34 [23-50], p = nonsignificant), and clinical diagnosis of inhalation injury (39% vs. 35%, p = nonsignificant). The primary outcome was ventilator-free days in the first 28 days after randomization. Intent-to-treat analysis revealed no significant difference between the high-frequency percussive ventilation and the low-tidal volume ventilation groups in mean (± sd) ventilator-free days (12 ± 9 vs. 11 ± 9, p = nonsignificant). No significant difference was detected between groups for any of the secondary outcome measures to include mortality except the need for "rescue" mode application (p = .02). Nine (29%) in the low-tidal volume ventilation arm did not meet predetermined oxygenation or ventilation goals and required transition to a rescue mode. By contrast, two in the high-frequency percussive ventilation arm (6%) required rescue. CONCLUSIONS: A high-frequency percussive ventilation-based strategy resulted in similar clinical outcomes when compared with a low-tidal volume ventilation-based strategy in burn patients with respiratory failure. However, the low-tidal volume ventilation strategy failed to achieve ventilation and oxygenation goals in a higher percentage necessitating rescue ventilation.

High-frequency percussive ventilation revisited.

High-frequency percussive ventilation (HFPV) has demonstrated a potential role as a rescue option for refractory acute respiratory distress syndrome and as a method for improving inhalation injury outcomes. Nevertheless, there is a lack of literature examining the practical application of HFPV theory toward either improving gas exchange or preventing possible ventilator-induced lung injury. This article will discuss the clinically pertinent aspects of HFPV, inclusive of high- and low-frequency ventilation.

Inhaled prostacyclin in combination with high-frequency percussive ventilation.

We present a case of severe acute respiratory distress syndrome pursuant to inhalation of a compressed gas computer keyboard cleaner. Despite the use of multimodal therapy to include empiric antibiotics, intravenous paralytics, intravenous concentrated albumin, high-dose corticosteroids as well as sustained high mean airway pressure mechanical ventilation by airway pressure release and high-frequency percussive ventilation (HFPV) modes, the patient demonstrated an unchanging arterial oxygen tension/fraction of inspired oxygen ratio of only 57 mm Hg. A trial of nebulized prostacyclin was initiated during HFPV leading to a significant improvement in arterial oxygen tension/fraction of inspired oxygen to 147 mm Hg. The improved oxygen tension allowed for a reduction in mean airway pressure and oxygen concentration as well the safe aeromedical evacuation of the patient from the combat theater. Further, prospective studies are required to validate the magnitude of response to inhaled prostacyclin during HFPV.

Glucose variability is associated with high mortality after severe burn.

BACKGROUND: Hyperglycemia is associated with increased mortality in the severely injured; intensive insulin protocols reduce mortality, improve wound healing, and decrease susceptibility to infection. High glucose variability creates challenges to glycemic control and may be a marker of poor outcome. We wondered whether glycemic variability alone might identify patients at higher risk of death. METHODS: Burn patients admitted in 2005 with >20% total body surface area burned, >or=100 glucose measurements, and one hypo- and hyperglycemic event were included in the analysis; all were treated with intensive insulin (glycemic target: 80-110 mg/dL). Glycemic variability was the sum of percent excursions (defined as values <80 mg/dL or >110 mg/dL); variability above the mean was considered high. RESULTS: Individual average variability in the 49 subjects was 50% +/- 8% (range, 30-65%); the average number of glucose measurements per patient was 840 (range, 103-5314). Percent excursions in those with high (n = 26) compared with low (n = 23) variability scores was 56% +/- 6% and 43% +/- 5% (p < 0.001), respectively. No difference was found between groups in injury severity score, age, total body surface area burned, full thickness burns, gender, or inhalation injury. Both groups were similar for days of ventilator support, intensive care unit stay, and hospital stay. Mortality in the highly variable group was twice that of the less variable group (50% vs. 22%, p = 0.041). CONCLUSIONS: High glucose variability (>50% of values outside 80-110 mg/dL) is associated with increased mortality in the severely burned. Individuals with frequent excursions outside the glucose target range of 80 mg/dL to 110 mg/dL are at greater risk of death.

Critical care at Landstuhl Regional Medical Center.

BACKGROUND: Landstuhl Regional Medical Center is the largest U.S. medical facility outside the United States, and it is the first permanently positioned hospital outside the combat zone providing care to the wartime sick and wounded. As of November 2007, Landstuhl Regional Medical Center personnel have treated over 45,000 patients from Operations Enduring Freedom and Iraqi Freedom. The current trauma/critical care service is a multidisciplinary, intensivist-directed team caring for a diverse range of clinical diagnoses to include battle injuries, diseases, and nonbattle injuries. Admissions arise from an at-risk population of 500,000 widely distributed over a geographic area encompassing three continents. DISCUSSION: When compared with 2001, the average daily intensive care unit census has tripled and the patient acuity level has doubled. Combat casualties account for 85% of service admissions. The clinical practice at this critical care hub continues to evolve as a result of wartime damage control trauma care, robust critical care air transport capabilities, length of stay, and other unique factors. The service's focus is to optimize patients for an uneventful evacuation to the United States for definitive care and family support. SUMMARY: Successful verification in 2007 as an American College of Surgeons level II trauma center reflects a continuing institutional commitment to providing the best possible care to the men and women serving our nation in the global war on terror.

Global evacuation of burn patients does not increase the incidence of venous thromboembolic complications.

BACKGROUND: Case-control studies have suggested that air travel may be a risk factor for the development of Venous Thromboembolism (VTE). Burned patients from the current war in Iraq and Afghanistan, are transported across three continents to our Burn Center with total ground and air transport time being approximately 24 hours spread over 3 days to 4 days. We hypothesized global evacuation results in increased VTE rates. METHODS: Retrospective review of 1,107 consecutive patients admitted to our burn center from January 2003 to December 2005. RESULTS: In the time period evaluated, no detectible differences were found in incidence of VTE between air-evacuated soldiers and those admitted to our facility from South Texas (1.31% vs. 0.83%, p = ns). The air-evacuated soldiers were younger (26 +/- 7 vs. 41 +/- 19, p < 0.0001) but had a higher incidence of inhalation injury (14.4% vs. 8.0%, p < 0.0001) and higher Injury Severity Score (10.9 +/- 13.0 vs. 6.5 +/- 9.2, p < 0.0001). No difference in average percent total body surface area involvement was found (15.8 +/- 19.4 vs. 15.5 +/- 18.4, p = ns). Overall, 11 of 1,107 (0.99%) burned patients developed VTE. CONCLUSION: Prolonged global evacuation is not associated with increased risk of VTE.

Long range transport of war-related burn casualties.

BACKGROUND: US military burn casualties are evacuated to the US Army Institute of Surgical Research Burn Center in San Antonio, TX. Patients are transported by US Army Institute of Surgical Research Burn Flight Teams, Air Force Critical Care Air Transport Teams, or routine aeromedical evacuation. This study characterizes the military burn casualties transported by each team and reports associated outcomes. METHODS: We performed a retrospective review of burn center registry data, identifying all US burn casualties admitted to the Army's burn center between March 2003 and February 2007. Data included total body surface area (TBSA) burn, ventilatory status, inhalational injury, associated injuries, injury severity, disposition, morbidity, and mortality. RESULTS: During 4 years of military operations in Iraq and Afghanistan, 540 casualties were admitted to our burn center for treatment of injuries resulting from war-related operations. Mean burn size was 16.7% total body surface area (range, <1%-95%) with a mean Injury Severity Score of 12.2 +/- 13.7. One hundred eight-one (33.5%) casualties required ventilatory support in flight; inhalation injury was confirmed in 69 (12.7%) patients. Two hundred six (38.1%) were transported by the Burn Flight Team and 174 (32.2%) were transported by Critical Care Air Transport Team, with a mean transit time of 4 days after injury. One hundred sixty (29.6%) patients were routine aeromedical evacuees. There were no in-flight deaths reported; 30 (5.6%) patients died of their wounds at our burn center. CONCLUSIONS: Burn casualties represent a group of patients with severe traumatic injuries. Our current system of selectively using specialty medical transport teams for the long-range transport of burn casualties is safe and effective.

Patterns of exogenous insulin requirement reflect insulin sensitivity changes in trauma.

INTRODUCTION: We investigated patterns of blood glucose and exogenous insulin requirement in the intensive care unit, and questioned whether they reflect fluctuations in insulin activity. METHODS: Records for burn intensive care unit patients with 7 days of glucose control with insulin were reviewed. Hourly blood glucose and insulin dose were matched for time collected and analyzed with linear and cosine regression. Frequency analysis identified recurring patterns. RESULTS: Diurnal patterns of blood glucose and insulin requirement were noted (insulin troughs = noon; insulin peaks = midnight; glucose troughs = 5 am; glucose peaks = 5 pm). Average insulin requirement increased at a constant linear rate (slope = .013, r2 = .57, P < or = .001). CONCLUSIONS: Diurnal patterns in blood glucose and insulin requirement mirror those of healthy subjects and may reflect persistence of normal variability in insulin activity. The 5-hour offset in peaks and troughs is suggestive of complex interplay between insulin availability and receptor sensitivity. The insulin requirement to blood glucose ratio increased, evidence that insulin resistance progresses over time.

Cricothyroidotomy for elective airway management in critically ill trauma patients with technically challenging neck anatomy.

INTRODUCTION: To assess the value of elective cricothyroidotomy for airway management in critically ill trauma patients with technically challenging neck anatomy. MATERIALS AND METHODS: A retrospective chart review of patients admitted to the Trauma Service at a Level I Trauma Center who underwent cricothyroidotomy for elective airway management over a 40-month period from January 1997 to April 2000. Comparison was made with a cohort of Trauma Service patients who received a tracheostomy. RESULTS: Eighteen patients met study criteria, and an unpaired t test revealed significance (P < 0.05) for age only. There was no difference with Injury Severity Score, number of days in the intensive care unit, number of days requiring ventilation post procedure or number of days intubated prior to procedure. The major difference was the more technically challenging neck anatomy in the patients undergoing cricothyroidotomy. Five out of 18 patients undergoing cricothyroidotomy died prior to discharge and two out of 18 died after discharge from complications unrelated to their airway. Two out of 18 patients undergoing tracheostomy died prior to discharge from complications unrelated to their airway. For a period of 1 week-15 months (average, 5.5 months), notes in subsequent clinic appointments were reviewed for subjective assessment of wound healing, breathing and swallowing difficulties, and voice changes. One patient with a cricothyroidotomy required silver nitrate to treat some granulation tissue. Otherwise, no complications were identified. Telephone interviews were conducted with eight of the 11 surviving cricothyroidotomy patients and nine of the 16 surviving tracheostomy patients. One tracheostomy patient required surgical closure 3 months after discharge; otherwise, the only noted change was minor voice changes in three patients in each group. All six of these patients denied that this compromised them in any way. CONCLUSION: Elective cricothyroidotomy has a low complication rate and is a reasonable, technically less demanding option in critically ill patients with challenging neck anatomy requiring a surgical airway.

A protocolized approach to pulmonary failure and the role of intermittent prone positioning.

INTRODUCTION: We present a series of adult patients treated under a protocol for severe lung failure (acute respiratory distress syndrome [ARDS]) that uses positive end-expiratory pressure (PEEP) optimization and intermittent prone positioning (IPP) to reduce shunt, improve oxygen (O(2)) delivery, and reduce FiO(2). METHODS: Trauma, emergency vascular, and general surgical patients with PaO(2)/FiO)(2) (PF) ratio < 200 were entered into a protocol designed to maintain mixed venous saturation (SVO(2)) > 70% with FiO(2) < 0.50. Therapy involved a sequential algorithmic approach that included pulmonary artery oximetry, "best-PEEP" determination, optimization of cardiac function, limitation of VO(2), transfusion to hematocrit of 35%, frequent bronchoscopy, rational diuresis and, if the FiO(2) was > 0.50, a trial of IPP with every-6-hour rotations. Unstable spine fractures and pelvic external fixators were the only contraindications to IPP. We collected data prospectively and from the charts and trauma registry. RESULTS: Forty adults were treated by protocol, 29 were injured and 11 had vascular or general surgical primary problems. The patients were 46.3 +/- 3.1 years old (the trauma patients were 42.9 +/- 3.2, and the vascular/general patients were 62 +/- 7.5 years old). Average Injury Severity Score was 25.9 +/- 3.7 and the Murray lung injury score was 2.65 +/- 0.9. IPP was used in all patients including those with recent tracheostomy, open abdomens, laparotomy, thoracotomy, leg external fixators, central nervous system injury, continuous venovenous hemofiltration and extracorporeal membrane oxygenation cannulae, vasopressor therapy, recent chest wall open reduction and internal fixation, and facial fractures. With the initiation of IPP therapy, the PF ratio increased from 132.1 +/- 8.5 to 231.6 +/- 14.2 (p < 0.001), the FiO(2) was decreased from 65.9 +/- 4.0% to 47.0 +/- 1.1% (p < 0.001), and the SVO(2) increased from 75.3 +/- 1.8% to 78.6 +/- 1.6% (p = 0.023). PEEP and static compliance were unchanged. The duration of IPP was 85.6 +/- 14.9 hours (median, 55 hours; range, 12 to 490 hours). Within 48 hours, all patients were on FiO(2) < or = 50. Mortality was 20% (14% for trauma) and none died of ARDS. The only complications of IPP were one case of partial-thickness skin loss from a malpositioned nasogastric tube and a case of transient lingual edema. CONCLUSION: IPP was independently responsible for an increase in PF ratio and SVO(2). We effectively and safely used IPP in our patients with ARDS, including many with issues generally considered to be contraindications. IPP and best-PEEP therapy enabled us to wean all of our patients' Fio2 to < or = 0.50 within 48 hours of ARDS onset.