Correlation of Impulse Oscillometry with Spirometry in Deployed Military Personnel with Airway Obstruction.

INTRODUCTION: Evaluation of chronic respiratory symptoms in deployed military personnel has been conducted at Brooke Army Medical Center as part of the Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures III study. Although asthma and airway hyperreactivity have been the most common diagnoses, the clinical findings in these patients may be multifactorial. This study aims to evaluate the utility of impulse oscillometry (IOS) in diagnosing airway obstruction in patients undergoing multiple pulmonary function testing (PFT) studies. METHODS: Military personnel referred for deployed-related pulmonary symptoms underwent a standardized evaluation at Brooke Army Medical Center and Walter Reed National Military Medical Center over a 5-year span. Initial studies included laboratory tests, high-resolution computed tomography imaging, cardiac evaluation with electrocardiogram, and echocardiography. PFT consisted of full PFTs, forced inspiratory/expiratory pressures, post-spirometry bronchodilator testing, IOS, exhaled nitric oxide, and methacholine challenge testing. RESULTS: A total of 360 patients have completed an evaluation to date. In this cohort, 108 patients (30.0%) have evidence of obstruction by spirometry, whereas 74 (20.6%) had IOS values of both an R5 > 150% and X5 < -1.5. Only 32 (8.9%) had evidence of obstruction by both spirometry and IOS, whereas 210 (57.3%) had neither. A comparison among R5 (resistance at 5 Hz), R20 (resistance at 20 Hz), and X5 (reactance at 5 Hz) was performed in those individuals with and without spirometric obstruction. R5 (% predicted) was 156.2 ± 57.4% (obstruction) vs. 129.1 ± 39.6% (no obstruction) (P < .001); R20 (% predicted) was 138.1 ± 37.7% (obstruction) vs. 125.3 ± 31.2% (no obstruction) (P = .007); and X5 (cmH2O/L/s) was -1.62 ± 1.28 (obstruction) vs. -1.25 ± 0.55 (no obstruction) (P < .001). DISCUSSION: Impulse oscillometry has been advocated as a supplemental pulmonary function test to aid in the diagnosis of airway obstruction. The use of IOS has been primarily used in pediatrics and elderly populations as a validated tool to establish a diagnosis of airway obstruction but is limited in the adult population because of a well-validated set of reference values. Prior studies in adults have most often demonstrated a correlation with an elevated R5 > 150%, elevated resonant frequency, and a negative X5 < -1.5 or a decrease of 30 to 35% in R5 post-bronchodilator. CONCLUSION: Impulse oscillometry may serve as an adjunct to diagnosis but likely cannot replace a standard spirometric evaluation. Our study highlights the future utility for diagnosing early obstructive disease in the symptomatic individual.

Improved Adherence to Best Practice Ventilation Management After Implementation of Clinical Practice Guideline (CPG) for United States Military Critical Care Air Transport Teams (CCATTs).

BACKGROUND: Critical Care Air Transport Teams (CCATTs) play a vital role in the transport and care of critically ill and injured patients in the combat theater to include mechanically ventilated patients. Previous research has demonstrated improved morbidity and mortality when lung protective ventilation strategies are used. Our previous study of CCATT trauma patients demonstrated frequent non-adherence to the Acute Respiratory Distress Syndrome Network (ARDSNet) protocol and a corresponding association with increased mortality. The goals of our study were to examine CCATT adherence with ARDSNet guidelines in non-trauma patients, compare the findings to our previous publication of CCATT trauma patients, and evaluate adherence before and after the publication of the CCATT Ventilator Management Clinical Practice Guideline (CPG). METHODS: We performed a retrospective chart review of ventilated non-trauma patients who were evacuated out of theater by Critical Care Air Transport Teams (CCATT) between January 2007 and April 2015. Data abstractors collected flight information, oxygenation status, ventilator settings, procedures, and in-flight assessments. We calculated descriptive statistics to determine the frequency of compliance with the ARDSNet protocol before and after the CCATT Ventilator CPG publication and the association between ARDSNet protocol adherence and in-flight events. RESULTS: We reviewed the charts of 124 mechanically ventilated patients transported out of theater via CCATT on volume control settings. Seventy percent (n = 87/124) of records were determined to be Non-Adherent to ARDSNet recommendations predominately due to excessive tidal volume settings and/or high FiO2 settings relative to the patient's positive end-expiratory pressure setting. The Non-Adherent group had a higher proportion of in-flight respiratory events. Compared to our previous study of ventilation guideline adherence in the trauma population, the Non-Trauma population had a higher rate of non-adherence to tidal volume and ARDSNet table recommendations (75.6% vs. 61.5%). After the CPG was rolled out, adherence improved from 24% to 41% (P = 0.0496). CONCLUSIONS: CCATTs had low adherence with the ARDSNet guidelines in non-trauma patients transported out of the combat theater, but implementation of a Ventilator Management CPG was associated with improved adherence.

Developing Military Doctors: An Institutional Approach to Medical Force Readiness in Graduate Medical Education.

Military physicians are required to not only meet civilian accreditation standards upon completion of their Graduate Medical Education (GME) training programs but also be proficient in the military-unique aspects of their field, including medical care in austere environments and management of combat casualties. They must also be familiar with the administrative and leadership aspects of military medicine, which are often absent from the training curriculum. The San Antonio Uniformed Services Health Education Consortium Military Readiness Committee, by incorporating questions of military relevance into each GME program's mandatory Annual Program Evaluation, identified curricular gaps upon which military readiness training objectives and opportunities were developed. These activities included a lecture series on the sustainment of medical and military readiness, an interactive procedural skills training event, trainee involvement in operational pre-deployment exercises, and the development of an elective operational rotation in Honduras. The Military Readiness Committee provides a model for other military GME institutions to develop training goals and opportunities to strengthen the preparedness of their trainees for military service.

Baseline Spirometry as a Predictor of Positive Methacholine Challenge Testing for Exertional Dyspnea.

BACKGROUND: There are several tests recommended by the American Thoracic Society (ATS) to evaluate for airway hyper-responsiveness (AHR), one of which is methacholine challenge testing (MCT). Few studies have examined the correlation of baseline spirometry to predict AHR in MCT, especially in the younger, relatively healthy military population under clinical evaluation for symptoms of exertional dyspnea. The study aim was to retrospectively correlate baseline spirometry values with MCT responsiveness. METHODS: This study is a retrospective review of all MCT performed at Brooke Army Medical Center/Wilford Hall Medical Center over a 12-y period; all completed studies were obtained from electronic databases. The following parameters were analyzed from the studies: baseline FEV1, FVC, FEV1/FVC, mid-expiratory flow (FEV25-75%), FEV25-75%/FVC. Studies were categorized based on baseline obstruction, restriction, FEF25-75% lower limit of normal, and response to bronchodilator testing (if completed); these values were compared based on methacholine reactivity and severity. RESULTS: Methacholine challenge studies (n = 1,933) were reviewed and categorized into reactive (n = 577) and nonreactive (n = 1,356) as determined by ATS guidelines. The mean baseline FEV1 (% predicted) with MCT reactivity was 88.0 ± 13.0% versus no MCT reactivity was 92.7 ± 13.0% (P < .001). The mean baseline FVC (% predicted) was 93.1 ± 13.7% versus 95.3 ± 13.5% (P < .001). The mean baseline FEV25-75% (% predicted) was 80.0 ± 22.1% versus 89.0 ± 23.4% (P < .001). Based on partition analysis, methacholine reactivity was most prevalent with baseline obstruction, n = 115 (43%), and in the absence of obstruction, when the FEF25-75% (% predicted) was below 0.70, n = 111 (40%). The negative predictive value with normal spirometry was 73%. CONCLUSIONS: The analysis of baseline spirometry prior to MCT proved useful in the evaluation of exertional dyspnea in a military population. The presence of airways obstruction (FEV1/FVC < lower limit of the normal range) followed by a reduction in FEV25-75% < 70% predicted showed a positive correlation with underlying AHR. In patients with exertional dyspnea and normal baseline spirometry, the use of the FEF25-75% may be a useful surrogate measurement to predict reactivity during MCT and consideration for additional testing or treatment.

Critical Care Education and Skills Validation Course for Internal Medicine Physicians in the Military.

INTRODUCTION: Military internist and internal medicine (IM) subspecialist physicians must be prepared to function in both traditional inpatient and outpatient settings, as well as manage critically ill patients within a deployed austere environment. As many critical care procedures are not performed on a routine basis in general IM practice, many active duty IM physicians experience skills degradation and lack confidence in performing these procedures. In order to address this perceived deficiency, the U.S. Army and Air Force Internal Medicine Education and Skills Validation Course was developed to provide essential training in critical care procedures for active duty military IM physicians and subspecialists. MATERIALS AND METHODS: Staff internist and subspecialist physicians at multiple military treatment facilities participated in a 2-day simulation-based training course in critical care procedures included in the Army Individual Critical Task Lists and the Air Force Comprehensive Medical Readiness Program. Educational content included high-yield didactic lectures, multi-disciplinary Advanced Cardiac Life Support/Advanced Trauma Life Support high-fidelity simulation scenarios, and competency training/validation in various bedside procedures, including central venous and arterial line placement, trauma-focused ultrasound exam, airway management and endotracheal intubation, chest tube thoracotomy, and mechanical ventilation, among others. RESULTS: A total of 87 staff IM physicians participated in the course with an average of 2-4 years of experience following completion of graduate medical education. Upon course completion, all participants successfully achieved rigorous, checklist-based, standardized validation in all the required procedures. Survey data indicated a significant improvement in overall skills confidence, with 100% of participants indicating improvement in their ability to function independently as deployed medical officers. CONCLUSIONS: Broad implementation of this program at military hospitals would improve pre-deployment critical care procedural readiness in military IM physicians.

Isolated Small Airway Dysfunction and Ventilatory Response to Cardiopulmonary Exercise Testing.

BACKGROUND: The effect of isolated small airway dysfunction (SAD) on exercise remains incompletely characterized. We sought to quantify the relationship between isolated SAD, identified with lung testing, and the respiratory response to exercise. METHODS: We conducted a prospective evaluation of service members with new-onset dyspnea. All subjects underwent plethysmography, diffusing capacity of the lung for carbon monoxide (DLCO), impulse oscillometry, high-resolution computed tomography (HRCT), and cardiopulmonary exercise testing (CPET). In subjects with normal basic spirometry, DLCO, and HRCT, SAD measures were analyzed for associations with ventilatory parameters at submaximal exercise and at maximal exercise during CPET. RESULTS: We enrolled 121 subjects with normal basic spirometry (ie, FEV1, FVC, and FEV1/FVC), DLCO, and HRCT. Mean age and body mass index were 37.4 ± 8.8 y and 28.4 ± 3.8 kg/m2, respectively, and 110 (90.9%) subjects were male. The prevalence of SAD varied from 2.5% to 28.8% depending on whether FEV3/FVC, FEF25-75%, residual volume/total lung capacity, and R5-R20 were used to identify SAD. Agreement on abnormal SAD across tests was poor (kappa = -0.03 to 0.07). R5-R20 abnormalities were related to higher minute ventilation ([Formula: see text]) and higher [Formula: see text]/maximum voluntary ventilation (MVV) during submaximal exercise and to lower [Formula: see text] during maximal exercise. After adjustment for differences at baseline, there remained a trend toward a relationship between R5-R20 and an elevated [Formula: see text]/MVV during submaximal exercise (ß = 0.04, 95% CI -0.01 to 0.09, P = .10), but there was no significant association with [Formula: see text] during submaximal exercise or with [Formula: see text] during maximal exercise. No other SAD measures showed a relationship with ventilatory parameters. CONCLUSIONS: In 121 subjects with normal basic spirometry, DLCO, and HRCT, we found poor agreement across tests used to detect SAD. Among young, healthy service members with postdeployment dyspnea, SAD as identified by lung function testing does not predict changes in the ventilatory response to exercise.

Clinical Evaluation of Deployed Military Personnel With Chronic Respiratory Symptoms: Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures (STAMPEDE) III.

BACKGROUND: Chronic respiratory symptoms are frequently reported after Southwest Asia deployment in support of combat operations. The full spectrum of clinical lung diseases related to these deployments is not well characterized. METHODS: Military personnel with chronic symptoms, primarily exertional dyspnea, underwent a standardized cardiopulmonary evaluation at two tertiary medical centers. Pulmonary function testing consisted of spirometry, lung volume, diffusing capacity, impulse oscillometry, and bronchodilator testing. Further testing included methacholine challenge, exercise laryngoscopy, high-resolution CT scan, ECG, and transthoracic echocardiography. RESULTS: A total of 380 participants with a mean age of 38.5 ± 8.4 years completed testing. Asthma was the most common diagnosis in 87 patients (22.9%) based on obstructive spirometry/impulse oscillometry and evidence of airway hyperreactivity, whereas another 57 patients (15.0%) had reactivity with normal spirometry. Airway disorders included 25 (6.6%) with laryngeal disorders and 16 (4.2%) with excessive dynamic airway collapse. Interstitial lung disease was identified in six patients (1.6%), whereas 11 patients (2.9%) had fixed obstructive lung disorders. Forty patients (10.5%) had isolated pulmonary function abnormalities and 16 (4.2%) had miscellaneous disorders. The remaining 122 patients (32.1%) with normal studies were classified as undiagnosed exertional dyspnea. Significant comorbidities identified included elevated BMI > 30 kg/m2 (34.2%), smoking (36.4%), positive allergy testing (43.7%), sleep apnea (38.5%), and esophageal reflux (13.6%). Mental health disorders and posttraumatic stress disorder were likewise common. CONCLUSIONS: Postdeployment pulmonary evaluation should focus on common diseases, such as asthma and airway hyperreactivity, and include testing for upper airway disorders. Diffuse lung diseases were rarely diagnosed, whereas numerous comorbidities were common.

Right Ventricular Failure Following Patent Foramen Ovale Closure on Venovenous-Extracorporeal Membrane Oxygenation.

We present a patient with pulmonary arterial hypertension requiring venovenous-extracorporeal membrane oxygenation for acute respiratory distress syndrome. Refractory hypoxemia secondary to right-to-left interatrial shunting via a patent foramen ovale was discovered. Right heart catheterization with invasive occlusion test heralded worsening right heart failure so closure was aborted. (Level of Difficulty: Intermediate.).

Chronic Left Lower Lobe Pulmonary Infiltrates During Military Deployment.

Deployment to Southwest Asia is associated with increased airborne hazards such as geologic dusts, burn pit smoke, vehicle exhaust, or air pollution. There are numerous ongoing studies to evaluate the potential effects of inhaled particulate matter on reported increases in acute and chronic respiratory symptoms. Providers need to be aware of potential causes of pulmonary disease such as acute eosinophilic pneumonia, asthma, and vocal cord dysfunction that have been associated with deployment. Other pulmonary disorders such as interstitial lung disease are infrequently reported. Not all deployment-related respiratory complaints may result from deployment airborne hazards and a broad differential should be considered. We present the case of a military member with a prolonged deployment found to have lobar infiltrates secondary to pulmonary vein stenosis from treatment for atrial fibrillation.

Spread of vaccinia virus through shaving during military training, Joint Base San Antonio-Lackland, TX, June 2014.

Although naturally occurring smallpox virus was officially declared eradicated in 1980, concern for biological warfare prompted the U.S. Government in 2002 to recommend smallpox vaccination for select individuals. Vaccinia, the smallpox vaccine virus, is administered into the skin, typically on the upper arm, where the virus remains viable and infectious until the scab falls off and the epidermis is fully intact - typically 2-4 weeks. Adverse events following smallpox vaccination may occur in the vaccinee, in individuals who have contact with the vaccinee (i.e., secondary transmission), or in individuals who have contact with the vaccinee's contact (i.e., tertiary transmission). In June 2014 at Joint Base San Antonio-Lackland, TX, two cases of inadvertent inoculation of vaccinia and one case of a non-viral reaction following vaccination occurred in the security forces training squadron. This includes the first reported case of shaving as the likely source of autoinoculation after contact transmission. This paper describes the diagnosis and treatment of these cases, the outbreak investigation, and steps taken to prevent future transmission.