Acute eosinophilic pneumonia in the deployed military setting

RATIONALE

Acute eosinophilic pneumonia (AEP) is a rare but important cause of severe respiratory failure most typically caused by cigarette smoking, but can also be caused by medications, illicit drugs, infections and environmental exposures. There is growing evidence that disease severity varies and not all patients require mechanical ventilation or even supplemental oxygen.

OBJECTIVES

To compare patients with AEP treated at Landstuhl Regional Medical Center (LRMC) to those in other published series, and to provide recommendations regarding diagnosis and treatment of AEP.

METHODS

A retrospective chart review was completed on forty-three cases of AEP which were identified from March 2003 through March 2010 at LRMC, Germany.

RESULTS

Tobacco smoking was reported by 91% of our patients. Only 33% of patients in our series had a fever (temperature > 100.4 °F) at presentation. Peripheral eosinophilia (>5%) was present in 35% on initial CBC, but was seen in 72% of patients during their hospital course. Hypoxemia, as measured by PaO2/FiO2 ratio, seemed to be less severe in patients with higher levels of bronchoalveolar (BAL) eosinophilia percentage.

CONCLUSIONS

Based on our experience and literature review, we recommend adjustments to the diagnostic criteria which may increase consideration of this etiology for acute respiratory illnesses as well as provide clinical clues we have found particularly helpful. Similar to recent reports of initial peripheral eosinophilia correlating with less severe presentation we found that higher BAL eosinophilia correlated with less severe hypoxemia.

Health care response to CCHF in US soldier and nosocomial transmission to health care providers, Germany, 2009

Early recognition and implementation of appropriate infection control measures were effective in preventing further transmission.

In 2009, a lethal case of Crimean–Congo hemorrhagic fever (CCHF), acquired by a US soldier in Afghanistan, was treated at a medical center in Germany and resulted in nosocomial transmission to 2 health care providers (HCPs). After his arrival at the medical center (day 6 of illness) by aeromedical evacuation, the patient required repetitive bronchoscopies to control severe pulmonary hemorrhage and renal and hepatic dialysis for hepatorenal failure. After showing clinical improvement, the patient died suddenly on day 11 of illness from cerebellar tonsil herniation caused by cerebral/cerebellar edema. The 2 infected HCPs were among 16 HCPs who received ribavirin postexposure prophylaxis. The infected HCPs had mild or no CCHF symptoms. Transmission may have occurred during bag-valve-mask ventilation, breaches in personal protective equipment during resuscitations, or bronchoscopies generating infectious aerosols. This case highlights the critical care and infection control challenges presented by severe CCHF cases, including the need for experience with ribavirin treatment and postexposure prophylaxis.

Diffuse alveolar hemorrhage: a rare manifestation of trauma

OBJECTIVE

Fat emboli syndrome (FES) is a disorder associated with both acute lung injury and acute respiratory distress syndrome. Both FES and diffuse alveolar hemorrhage (DAH) are bronchoscopically definable entities that may share a common etiology. We conducted a chart review analysis to examine the relationship between FES and DAH.

METHODS

Retrospective chart review.

RESULTS

Three cases of concurrent FES and DAH were identified. Long bone fracture and/or orthopedic procedures preceded all the events and were the likely inciting source for eventual acute lung injury. Bronchoalveolar lavage-evident DAH and FES was found in all these cases in association with hemoptysis and lung-attributed blood loss. Lung-protective ventilation and standard supportive care approaches proved sufficient in attaining good outcomes.

CONCLUSION

Combined FES and DAH can occur in association with orthopedic injury and repair and are likely an under-recognized entity.

The introduction of extracorporeal membrane oxygenation to aeromedical evacuation

OBJECTIVE

To review the principles of extracorporeal membrane oxygenation (ECMO) and to describe the recent advancements in ECMO technology that permit use of this rescue therapy for severe lung injury in combat casualties.

METHODS/RESULTS

Lung protective ventilation has defined the state-of-the-art treatment for acute lung injury for more than a decade. Despite the benefits provided by a low tidal volume strategy, lung injury patients may experience deterioration in gas exchange to the point that other rescue interventions are needed or the patient succumbs to progressive respiratory failure. When this occurs in combat casualties, management of the patient in an austere environment and movement to definitive care become problematic. Recent advances in ECMO technology permit long-range transport of these critically ill casualties with greater physiologic reserve and potentially less mortality.

CONCLUSIONS

Advances in ECMO technology now enable the stabilization and aeromedical evacuation of even the most critically ill combat casualties with severe lung injury.

Reversal of hemorrhagic shock-associated hepatic ischemia-reperfusion injury with N-acetylcysteine

BACKGROUND

The underpinning pathophysiology, prevalence, and clinical relevance particular to hemorrhagic shock-induced liver damage have been explored only recently. Importantly, several investigators have revealed that an aberrant periportal endothelial response, characterized by the early release of oxidizing mediators, perpetuates and eventually amplifies the extent of hepatic reperfusion injury.

CASE

We present a case that illustrates the clinical impact of hepatic ischemia-reperfusion injury and a potential means of ameliorating the attendant self-propagating hepatic destruction.

CONCLUSION

Reversal of hemorrhagic shock may lead to the induction of a hepatic oxidation response with a resultant furthering of liver injury. Antioxidants such as N-acetylcysteine may represent a tolerable and logical means of attenuating the aberrant oxidant cascade and stabilizing or reversing ischemic-reperfusion hepatopathy.

Intercontinental aeromedical evacuation of patients with traumatic brain injuries during Operations Iraqi Freedom and Enduring Freedom

Traumatic brain injury contributes significantly to military combat morbidity and mortality. No longer maintaining comprehensive medical care facilities throughout the world, the US military developed a worldwide trauma care system making the patient the moving part of the system. Life-saving interventions are performed early, and essential care is delivered at forward locations. Patients then proceed successively through increasingly capable levels of care culminating with arrival in the US. Proper patient selection and thorough mission preparation are crucial to the safe and successful intercontinental aeromedical evacuation of critical brain-injured patients during Operations Iraqi Freedom and Enduring Freedom.

High-frequency percussive ventilation: pneumotachograph validation and tidal volume analysis

INTRODUCTION

High-frequency percussive ventilation (HFPV) is an increasingly used mode of mechanical ventilation, for which there is no proven real-time means of measuring delivered tidal volume (V(T)).

OBJECTIVE

To validate a pneumotachograph for HFPV and then exploit flow-sensor data to describe the behavior of both low-frequency and high-frequency breaths.

METHODS

Sensor performance was gauged during changes in high-frequency (4-12 Hz) and low-frequency rate and ratio, mean airway pressure, oxygen concentration, heated or heated-humidified gas flow, and endotracheal tube diameter. Glass bottle (adiabatic V(T)) and test lung (adiabatically derived low-frequency V(T)) based adiabatic conditions provided both an initial source for analog-signal calibration and an accepted standard comparator to flow-sensor measurement of high-frequency and low-frequency (flow-sensor-derived) V(T)), respectively.

RESULTS

Pneumotachography proved accurate and precise over an array of tested settings and conditions when analyzing both high-frequency (difference between mean +/- SD high-frequency V(T) and adiabatic V(T) was -0.2 +/- 1.8%, 95% confidence interval -0.5 to 0.9%) and low-frequency breaths (mean +/- SD difference between flow-sensor-derived low-frequency V(T) and adiabatically derived low-frequency V(T) was 0.6 +/- 2.4%, 95% confidence interval 0.1-1.1%). High-frequency V(T) and frequency exhibited an exponential relationship. During HFPV, flow-sensor-derived low-frequency V(T) had a mean +/- SD of 1,337 +/- 700 mL, 95% confidence interval 1,175-1,499 mL.

CONCLUSIONS

Readily available pneumotachography provided accurate measurements of low-frequency and high-frequency V(T) during HFPV. In the setting of acute lung injury, typical HFPV settings may deliver injurious V(T).

Cardiopulmonary exercise test interpretation using age-matched controls to evaluate exertional dyspnea

BACKGROUND

Cardiopulmonary exercise testing (CPET) is one method to diagnose unexplained dyspnea in young adults, yet few normal reference values exist in this population. This study evaluated interpretation of maximal CPET in a young adult cohort with known pulmonary disorders using published reference values compared to age-matched normal controls.

METHODS

A control population of 69 healthy military volunteers with normal chest radiographs, pulmonary function testing, and bronchoprovocation testing were compared to 105 patients with exertional dyspnea. Both groups underwent a standardized evaluation including CPET on a graded exercise treadmill to maximal exercise with expired gas analysis.

RESULTS

Measurements from CPET in the dyspnea group were interpreted using published reference values compared to control population results (mean +/- 1.65 x SD). Statistical comparison of predicted normals (reference vs. control) of maximal oxygen consumption (> 83% vs. 82%), ventilatory anaerobic threshold (> 40% vs. 53%), respiratory rate (< 60 vs. 56 breaths/min), tidal volume to inspiratory capacity (< 80% vs. 111%), ventilatory equivalent for carbon dioxide production (< 40 vs. 38), and maximal voluntary ventilation minus minute ventilation (> 11 vs. -1 L/min) was performed. The overall specificity for tidal volume to inspiratory capacity improved using age-matched controls but sensitivity was decreased. Other parameters were not significantly different.

CONCLUSIONS

The use of age-matched controls for CPET results in an increase in specificity and decrease in sensitivity for respiratory limitations to exercise, when compared to reference values. The study findings suggest that CPET may be insensitive in detecting mild disease in young healthy adults.

Feasibility study of noninvasive ventilation with helium-oxygen gas flow for chronic obstructive pulmonary disease during exercise

BACKGROUND

Individually, noninvasive ventilation (NIV) and helium-oxygen gas mixtures (heliox) diminish ventilatory workload and improve exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). NIV in combination with heliox may have additive effects on exercise tolerance in severe COPD.

METHODS

We assessed the safety, tolerability, and efficacy of heliox and NIV during exercise in patients with severe COPD.

SETTING

Pulmonary rehabilitation facility in an academic tertiary-care medical center.

PROTOCOL

Twelve patients with severe COPD were enrolled. Using a sequential randomized placebo-controlled crossover study design, the patients performed 4 separate constant-work stationary bicycle cardiopulmonary exercise studies at 80% of maximal workload during application of sham NIV, NIV, 60:40 heliox with sham NIV, and 60:40 heliox with NIV. Tolerability, safety, and exercise duration as determined by constant-work cardiopulmonary exercise test were the primary outcome measures. Secondary outcome measures at peak exercise and iso-time included rate of perceived exertion, dyspnea, leg pain, heart rate, respiratory rate, systolic and diastolic blood pressure, tympanic temperature, and oxyhemoglobin saturation.

RESULTS

No adverse effects occurred during or after application of NIV, heliox, or NIV with heliox. Exercise duration using heliox with NIV was significantly longer than both heliox (P = .01) and NIV (P = .007), but not placebo (P = .09). Relative to placebo, all treatment arms permitted lower respiratory rates at peak exercise. Heliox, with or without NIV, was associated with significant improvements in oxyhemoglobin saturation at peak exercise, relative to placebo or NIV alone.

CONCLUSIONS

The adjunctive use of NIV with heliox during exercise proved both safe and tolerable in patients with severe COPD. The lack of demonstrable efficacy to any of the treatment arms relative to placebo (P = .09) may be the result of the small sample size (ie, type 2 error)-a conclusion emphasized by the large standard deviations and differences in treatment group variances in exercise duration alone.

Airway humidification during high-frequency percussive ventilation

BACKGROUND

We were concerned about the risk of inadequate humidification during high-frequency percussive ventilation (HFPV).

METHODS

We studied 5 humidifiers during HFPV with a lung model, at bias gas flows of 10 L/min, 30 L/min, and 50 L/min, and compared the results to those from a comparator ventilator/humidifier setup and to the minimum temperature (30 degrees C) and humidity (30 mg/L) [corrected] recommended by the American Association for Respiratory Care, at both regular room temperature and a high ambient temperature. Temperature was measured at the humidifier outflow point and at the artificial carina. Humidity was measured at the artificial carina.

RESULTS

Of the 7 HFPV/humidifier combinations, 2 (the MR850 at a bias flow of 50 L/min, and the ConchaTherm Hi-Flow with VDR nebulizer) provided a carinal temperature equivalent to the comparator setup at room temperature, whereas one HFPV/humidifier combination (the ConchaTherm Hi-Flow with modified programming, at bias flows of 30 L/min and 50 L/min) provided a higher carinal temperature. At high ambient temperature, all of the setups delivered lower carinal temperature than the comparator setup. Only 2 setups (the ConchaTherm with modified programming at a bias flow of 50 L/min, and the ConchaTherm Hi-Flow with VDR nebulizer) provided carinal humidification equivalent to the comparator setup, without regard to ambient temperature; the other humidifiers were less effective. The ConchaTherm with modified programming, and the ConchaTherm with the VDR nebulizer provided the most consistent humidification.

CONCLUSION

HFPV's distinctive gas-flow mechanism may impair gas heating and humidification, so all humidification systems should be tested with HFPV prior to clinical use.

Systematic review of the chronic care model in chronic obstructive pulmonary disease prevention and management

BACKGROUND

Implementation of the chronic care model (CCM) has been shown to be an effective preventative strategy to improve outcomes in diabetes mellitus, depression, and congestive heart failure, but data are lacking regarding the effectiveness of this model in preventing complications in patients with chronic obstructive pulmonary disease.

METHODS

We searched the MEDLINE, CINAHL, and Cochrane databases from inception to August 2005 and included English-language articles that enrolled adults with chronic obstructive pulmonary disease and (1) contained intervention(s) with CCM component(s), (2) included a comparison group or measures at 2 points (before/after), and (3) had relevant outcomes. Two reviewers independently extracted data.

RESULTS

Symptoms, quality of life, lung function, and functional status were not significantly different between the intervention and control groups. However, pooled relative risks (95% confidence intervals) for emergency/unscheduled visits and hospitalizations for the group that received at least 2 CCM components were 0.58 (0.42-0.79) and 0.78 (0.66-0.94), respectively. The weighted mean difference (95% confidence interval) for hospital stay was -2.51 (-3.40 to -1.61) days shorter for the group that received 2 or more components. There were no significant differences for those receiving only 1 CCM component.

CONCLUSIONS

Limited published data exist evaluating the efficacy of CCM components in chronic obstructive pulmonary disease management. However, pooled data demonstrated that patients with chronic obstructive pulmonary disease who received interventions with 2 or more CCM components had lower rates of hospitalizations and emergency/unscheduled visits and a shorter length of stay compared with control groups. The results of this review highlight the need for well-designed trials in this population.

Corrective measures for compromised oxygen delivery during endotracheal tube cuff deflation with high-frequency percussive ventilation

OBJECTIVE

To determine the effect of endotracheal-tube cuff deflation on airflow and F(IO2) during high-frequency percussive ventilation (HFPV), and explore methods of correcting the cuff-deflation-associated decrease in mean airway pressure and F(IO2) at the carina.

METHODS

Using a mechanical lung model in our respiratory research laboratory, we measured circuit pressure near the connection to the endotracheal tube (P(vent)), mean airway pressure (P(aw)), pulsatile tidal volume (V(T)), and F(IO2) at the artificial carina. During cuff deflation we manipulated the pulsatile frequency, pulsatile flow, and the HFPV integral nebulizer. We then assessed 4 methods of correcting the decreased F(IO2) and airway pressure during cuff deflation: (1) oxygen delivery at the inspiratory fail-safe valve, (2) oxygen delivery at the T-piece between the HFPV and the endotracheal tube, (3) continuous activation of the HFPV's integral nebulizer, and (4) oxygen insufflation into the suction channel of the endotracheal tube.

RESULTS

Cuff deflation reduced P(vent), P(aw), pulsatile V(T), and F(IO2). Increasing the pulsatile flow and decreasing the pulsatile frequency further reduced F(IO2) during cuff deflation. Injecting supplemental oxygen at the inspiratory fail-safe valve provided the best F(IO2) increase. Injecting oxygen at the T-piece provided the second best F(IO2) increase. Continuous activation of the integral nebulizer provided the third best F(IO2) increase. Oxygen insufflation to the suction channel was least effective in correcting the F(IO2) decrease caused by cuff deflation.

CONCLUSION

Cuff-deflation-associated F(IO2), P(aw), and pulsatile V(T) compromise can be partially corrected by any of the 4 methods we studied. Injecting supplemental oxygen at the inspiratory fail-safe valve is the most effective method.

Measurement of pulsatile tidal volume, pressure amplitude, and gas flow during high-frequency percussive ventilation, with and without partial cuff deflation

OBJECTIVE

With a high-frequency percussive ventilator and a mechanical lung model, to measure tidal volume (V(T)), pulsatile pressure amplitude (difference between peak and nadir pulsatile pressure [DeltaP];), and mean airway pressure (P (aw)) at various pulsatile frequencies, pulsatile inspiratory-expiratory ratios (I:E(p)), and pressures (measured at the interface between the pulse-generator and the endotracheal tube [P(vent)]).

METHODS

With the endotracheal tube inside an artificial trachea, we manipulated the high-frequency percussive ventilation settings and adjuncts, including pulsatile frequency, I:E(p), and P(vent) by manipulating pulsatile flow. We also studied the effects of partially deflating the endotracheal tube cuff. We measured P (aw), pulsatile pressure amplitude at the carina (DeltaP(c)), and pulsatile V(T) at the carina. With the cuff partly deflated, we measured the fraction of inspired oxygen (F(IO(2))) in the gas efflux above and below the cuff.

RESULTS

Increasing the pulsatile frequency from 300 cycles/min to 600 cycles/min and changing the I:E(p) from 1:3 to 1:1 significantly reduced V(T) (p < 0.001). P (aw) and DeltaP(c) were unaffected by the change in pulsatile frequency or I:E(p), except when we did not preserve the pulsatile flow. The measured V(T) range was from 19.1 mL (at 600 cycles/min) to 47.3 mL (at 300 cycles/min). Partial cuff deflation did not significantly reduce P (aw) or DeltaP(c), but it did significantly reduce V(T) and F(IO(2)).

CONCLUSION

During high-frequency percussive ventilation, the pulsatile frequency is inversely related to V(T). Partial cuff deflation reduces the delivered F(IO(2)).

Randomized placebo controlled assessment of airway inflammation due to racemic albuterol and levalbuterol via exhaled nitric oxide testing

STUDY OBJECTIVES

The S-stereoisomer found in racemic albuterol may have associated proinflammatory properties. We tested the hypothesis that airway inflammation as assessed by exhaled nitric oxide is no different in patients with COPD when using racemic albuterol relative to levalbuterol or placebo.

MEASUREMENTS

Twelve mild to moderate COPD patients were assigned to five days each of nebulized racemic albuterol, levalbuterol, and saline placebo. Before and after each course of treatment, airway inflammation was assessed via exhaled nitric oxide breath testing. Secondary functional outcomes that were measured included spirometry, a functional assessment utilizing a six-minute walk, and symptoms score using the University of California, San Diego Shortness of Breath Questionnaire.

RESULTS

There was no statistically significant difference in pre and post FeNO levels within and between treatment groups (p = 0.121). There were also no significant differences within or between treatment groups for the secondary outcome measurements of FEV1 (p = 0.913), functional assessment utilizing a six-minute walk (p = 0.838) and the symptom scores using Shortness of Breath Questionnaire (p = 0.500).

CONCLUSION

We found no difference in mild to moderate COPD patients treated with racemic albuterol, levalbuterol or placebo for measurement of exhaled nitric oxide or the secondary outcomes that were measured.

Progressive vocal cord dysfunction subsequent to a chlorine gas exposure

Chlorine gas inhalation, similar to other toxic gas exposures, can impart a variety of effects to the entire airway ranging from mucous membrane irritation to acute respiratory distress syndrome. The extent and location of damage is determined by numerous situational factors such as the duration of exposure, quantity of gas released, environmental factors, and instituted chemical defense measures. Reactive airways dysfunction and nonspecific bronchial hyperresponsiveness are commonly reported as sequelae to chlorine exposure. This article constitutes the first case of a single antecedent chlorine exposure inducing progressive vocal cord dysfunction.