Case Studies in Physiology: Untangling the cause of hypoxemia in a patient with obesity with acute leukemia.

Diagnosing the cause of hypoxemia and dyspnea can be complicated in complex patients with multiple comorbidities. This "Case Study in Physiology" describes an man with obesity admitted to the hospital for relapse of acute lymphoblastic leukemia, who experienced progressive hypoxemia, shortness of breath, and dyspnea on exertion during his hospitalization. After initial empirical treatment with diuresis and antibiotics failed to improve his symptoms and because an arterial blood gas measurement was not readily available, we applied a novel, recently described physiological method to estimate the arterial partial pressure of oxygen from the peripheral saturation measurement and calculate the alveolar-arterial oxygen difference to discern the source of his hypoxemia and dyspnea. Using basic physiological principles, we describe how hypoventilation, anemia, and the use of a ß blocker and furosemide, collaborated to create a "perfect storm" in this patient that impaired oxygen delivery and limited utilization. This case illustrates the application of innovative physiology methodology in medicine and provides a strong rationale for continuing to integrate physiology education in medical education.NEW & NOTEWORTHY Discerning the cause of dyspnea and hypoxemia in complex patients can be difficult. We describe the "real world" application of an innovative methodology to untangle the underlying physiology in a patient with multiple comorbidities. This case further demonstrates the importance of applying physiology to interrogate the underlying cause of a patient's symptoms when treatment based on probability fails.

Discordant Quantitative and Visual CT Assessments in the Diagnosis of Emphysema.

PURPOSE: Visual assessment of computed tomography (CT) of the lung is routinely employed in the diagnosis of emphysema. Quantitative CT (QCT) can complement visual CT but must be well validated. QCT emphysema is defined as ≥5% of lung volume occupied by low attenuation areas ≤-950 Hounsfield units (LAA-950). Discordant visual and QCT assessments are not uncommon. We examined the association between visual and quantitative chest CT evaluation within a large cohort of subjects to identify variables that may explain discordant visual and QCT findings. MATERIALS AND METHODS: Volumetric inspiratory CT scans of 1221 subjects enrolled in phase 1 of the COPDGene study conducted at the University of Iowa were reviewed. Participants included never smokers, smokers with normal spirometry, preserved ratio impaired spirometry, and Global Initiative for Obstructive Lung Disease (GOLD) stages I-IV. CT scans were quantitatively scored and visually interpreted by both the COPDGene Imaging Center and the University of Iowa radiologists. Individual-level visual assessments were compared with QCT measurements. Agreement between the two sets of radiologists was calculated using kappa statistic. We assessed variables associated with discordant results using regression methods. RESULTS: There was a fair agreement for the presence or absence of emphysema between our center's radiologists and QCT (61% concordance, kappa 0.22 [0.17-0.28]). Similar comparisons showed a slight agreement between the COPDGene Imaging Center and QCT (56% concordance, kappa 0.16 [0.11-0.21]), and a moderate agreement between both sets of visual assessments (80% concordance, kappa 0.60 [0.54-0.65]). Current smoking and female gender were significantly associated with QCT-negative but visually detectable emphysema. CONCLUSION: The slight-to-fair agreement between visual and quantitative CT assessment of emphysema highlights the need to utilize both modalities for a comprehensive radiologic evaluation. Discordant results may be attributable to one or more factors that warrant further exploration in larger studies. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT000608764.

Silo-Filler's Disease: One Health System's Experience and an Update of the Literature.

Silo-filler's disease, a life-threatening condition from exposure to silage gas in recently filled silos, has been known for over 5 decades now. However, farm workers remain exposed to this preventable condition. We describe the index presentations and subsequent changes among 19 patients managed within our health system over a 61-year period and highlight the need for ongoing education on minimizing exposure to silo gas.

Large endotracheal tumour presenting as severe COPD: flow-volume loop analysis, not always a straightforward diagnostic test.

The flow-volume loop (FVL) analysis is typically helpful in establishing the diagnosis of airway obstruction caused by endobronchial lesions. In this report, we describe a patient with emphysema and tobacco abuse who presented with chronic dry cough and severe chronic obstructive pulmonary disease (COPD) refractory to standard therapy. The initial FVL showed a relatively normal forced expiratory peak flow shape followed by a smooth flattening of the expiratory curve on spirometry, a pattern consistent with distal airway obstruction as seen in severe asthma or COPD. The patient was later found to have a large endotracheal mass. This atypical presentation, along with the unusual FVL, led to a significant delay in the diagnosis of the tracheal mass. A high level of suspicion is needed to diagnose variable intrathoracic airway obstruction in patients presenting with severe asthma or COPD who fail to improve with standard therapy.

Effectiveness of nasal irrigation for chronic rhinosinusitis and fatigue in patients with Gulf War illness: protocol for a randomized controlled trial.

INTRODUCTION: Gulf War Illness (GWI) affects 1 in 7 returned Persian Gulf War veterans. Quality-of-life impact is large; there is no cure. Chronic sinus symptoms and fatigue are common. Nasal irrigation with saline (NI-S) or xylitol (NI-X) improve sinus symptoms and fatigue in the general population. This trial will assess the effect of NI-S and NI-X on sinus and fatigue symptoms, economic outcomes and pro-inflammatory milieu among participants with GWI. METHODS: 75 participants (age 35 to 65 years, 25 in each of three arms) with GWI will be recruited from the Veteran's Administration and the community. They will use routine care for sinus symptoms and fatigue and be randomized to continued usual care alone or additional therapy with NI-S or NI-X. Participants will be able to adjust specific elements of the NI procedure. The primary outcome (Sinonasal Outcome Test, SNOT-20) and other self-reported assessments will occur at baseline, 8 and 26 weeks; lab assessment of pro-inflammatory cellular and cytokine profiles will occur at baseline and 26 weeks. Other outcomes will include fatigue-specific and overall health-related quality of life, pro-inflammatory cellular and cytokine profiles, cost-effectiveness and participant satisfaction. RESULTS: Baseline demographic and clinical data from the first 10 participants show effective participant recruitment, enrollment, randomization, retention and data collection. CONCLUSION: Early study conduct suggests that our participant-oriented approach will yield high rates of participant adherence and data capture, facilitating robust analysis. Results of this study will clarify the value of NI for chronic sinus symptoms and fatigue among patients with GWI. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov identifier NCT01700725.