BACKGROUND:In patients receiving pressure modes of mechanical ventilation, plateau pressure can be higher than peak inspiratory pressure when the patient has a strong drive to breathe. This report provides comprehensive evidence to support this observation. METHODS:Peak inspiratory pressure, plateau pressure, esophageal pressure, and tidal volume were observed at various levels of pressure support in a patient with absent cortical function but preserved brainstem function who was receiving mechanical ventilation. RESULTS:Positive end-expiratory pressure was 5 cm H2O for all pressure support settings. At pressure support of 0 cm H2O, plateau pressure was 13 cm H2O; peak inspiratory pressure was 5 cm H2O. The difference between plateau pressure and peak inspiratory pressure (8 cm H2O) reflected the patient's inspiratory effort. The driving pressure (8 cm H2O) generated a tidal volume of 619 mL. At pressure support of 10 cm H2O, plateau pressure was 12 cm H2O; peak inspiratory pressure was 15 cm H2O. The difference between plateau pressure and peak inspiratory pressure was -3 cm H2O, indicating absent inspiratory effort apart from triggering the breath. The driving pressure (7 cm H2O) generated a tidal volume of 563 mL. CONCLUSION:When plateau pressure can be accurately measured, the difference between plateau pressure and peak inspiratory pressure can be used at the bedside to evaluate a patient's respiratory drive. Ensuring protective goals by routinely monitoring plateau pressure regardless of the mode of mechanical ventilation is critical.

Background Chest wall strapping (CWS) is a technique that restricts the chest wall to induce breathing at lower lung volumes. CWS increases lung elastic recoil and expiratory airflows. In computer tomography imaging studies CWS dilates small airways in healthy and COPD-subjects. Dynamic-dysanapsis describes the concept of airway dilation via interdependence of airways and lung parenchyma from CWS induced increase in lung elastance. The time course of CWS induced dynamic-dysnapsis is not defined. Volumetric capnography and plethysmography allow for repeated measurements of the lung structure function relationship. We hypothesized that CWS causes an increase in dead space of COPD-subjects via CWS induced increase in airway dimensions. Secondly, we hypothesized that CWS increases airway homogeneity and that these effects last for a period after removal of CWS. Methods After performing baseline measurements (ventilation parameters, plethysmography, and volumetric capnography) participants with COPD (n = 5) and healthy, sex-matched controls (n = 5) underwent CWS. Measurements were repeated every 15 minutes for one hour following CWS. After CWS-removal measurements were repeated every 15 minutes for an additional hour. We related anatomic dead space, alveolar dead space, V D /V T , and slope of the capnogram to lung volume and tracked their changes over time. Results Moving from unstrapped to the CWS and to post-CWS condition, we saw an overall increase in the anatomic dead space (a surrogate with the size of the airway tree) for both groups with CWS and post-CWS (p = 0.001). The capnographic slope is an indicator of airway uniformity. Post-CWS had a significant effect on both groups causing a decrease in the slope of the capnogram to lung volume ratio, showing a significant increase in airway homogeneity (p = 0.03). Conclusion CWS dilates airways quantified by the increase in dead space. The increase in airway homogeneity persists at least 45 minutes after strapping is removed. This indicates lasting benefits of CWS on airway function. The dilatation of airways and the improvement in airway homogeneity during and after CWS could facilitate enhanced delivery of inhaled therapies in COPD. CWS should be further investigated as a novel non-pharmacological treatment for COPD.

Chest-Wall-Strapping (CWS), a technique forcing the lung to operate at low volumes, is a model for an oversized lung allograft. Dynamic-dysanapsis describes airway dilation mediated by increased elastic recoil from CWS. We hypothesized that Dynamic-dysanapsis can be quantified via the Dysanapsis-Ratio, defined as the airway-size to lung-volume ratio.Farm-raised pigs (n=3) were mechanically ventilated. Stepwise CT-images throughout the lung deflation limb in control and CWS conditions were analyzed quantifying airway dimensions and lung volume.CWS (30%-reduction in lung-volume) was associated with a significant increase in the Dysanapsis-Ratio (p<0.001). CWS increased airway distensibility at the 6th major branch of the right lower airway (27±7% vs. 39±5%, p=0.04).The dysanapsis-ratio allows quantification of dynamic-dysanapsis with CWS. Dynamic-dysanapsis appears to be a compensatory mechanism to preserve pulmonary gas exchange by airway dilation when the lung is forced to operate at lower lung volumes. Dynamic-dysanapsis furthers the understanding of oversized allografts in lung transplantation.

Introduction: Lung transplant recipients are at high risk for infections unusual in their presentation as well as causative organisms. While achromobacter species infections are recognized in patients who received a lung transplant for cystic fibrosis, it is rare for this infection to occur in patients with lung disease from other causes. Here, we present an unusual case of Achromobacter xylosoxidans infection in a bilateral lung transplant recipient with pulmonary fibrosis. Description of Case: A 67-year-old woman awaiting lung transplant for hypersensitivity pneumonitis induced pulmonary fibrosis was admitted to the intensive care unit for acute on chronic hypoxic respiratory failure requiring high flow nasal cannula oxygen at 80% FiO2. She had been treated for her lung condition with mycophenolate mofetil and prednisone. One week after admission, she underwent bilateral lung transplant receiving induction with basiliximab and methylprednisone per institutional protocol. She had no evidence of primary graft dysfunction; however, bronchoscopy completed at post-transplant days 7 and 10 showed mild ischemic injury at the medial right anastomosis. She was discharged home without oxygen. At her bronchoscopy one month post-transplant, black discoloration was identified throughout the tracheobronchial tree. Broncheoalveolar lavage (BAL) resulted positive for aspergillus galactomannan, and her voriconazole dose was increased to therapeutic range. Bronchoscopy two months post-transplant showed thick grey secretions adherent to the right anastomosis partially obstructing the right mainstem. BAL was again positive for aspergillus galactomannan, and newly positive for achromobacter species. She underwent endobronchial biopsy of the lesion, which also demonstrated achromobacter xylosoxidans with areas of necrosis and abscess formation. A computed tomography (CT) scan demonstrated scattered ground glass opacities. Given radiographic changes, multiple positive histopathologic specimens, and visual evidence of infection, the patient received six weeks of treatment with ceftazidime and inhaled polymyxin E. Subsequent bronchoscopy at six months post-transplant demonstrated complete resolution of right anastomotic lesion and negative BAL cultures. Discussion:Achromobacter xylosoxidans is a non-fermenting gram negative bacterium that produces colorless bacterial colonies; it is capable of causing colonization, as was initially suspected in our patient, but can also result in infections characterized by dark discoloration in immunocompromised individuals. In a retrospective study of a 288 person lung transplant cohort, only 2 non-cystic fibrosis patients had achromobacter xylosoxidans infections; similar to this patient, both had a history of pulmonary fibrosis. This case highlights the spectrum of achromobacter infections and the role of repeat post-transplant bronchoscopies in managing opportunistic infections.

Lung transplantation (LTx) is an important treatment option for many end-stage lung diseases. The goal of LTx is to restore pulmonary physiology (gas exchange and respiratory system mechanics) towards normal, so that LTx recipients can experience an improved quality of life and live significantly longer. An optimized approach to donor-to-recipient size matching is a strategy to increase opportunities for successful transplants and optimize outcomes. In this review we discuss relevant pulmonary gas exchange and respiratory systems mechanics principles as a framework to optimize donor-to-recipient size matching and LTX-recipient management. The predicted total lung capacity (pTLC) is a refined estimate of organ size utilizing regression equations to calculate lung size based on height, sex and age. In general, irrespective of the underlying lung disease the chest cavity is "reverse remolding" back towards normal size in most recipients. The parameter that can reflect the sizing goal to restore physiology towards normal is the recipient pTLC. A pragmatic size matching metric is the donor-to-recipient pTLC-ratio. Significant undersizing based on the pTLC-ratio is a risk factor for complications and lower LTx survival. If significant changes to the LTx candidate's chest cavity size occur (as can occur in severe restrictive lung disease or severe emphysema), or if the chest cavity cannot "reverse remodel" towards normal, it is important to consider additional donor-to-recipient sizing metrics. In addition to the recipient's measured actual total lung capacity imaging-based metrics can be considered. Chest X-ray and computer tomography based volumetric analyses can provide information facilitating a successful LTx.

Restrictive lung disease (RLD) is the leading indication for lung transplantation. Donor-to-recipient size matching is challenging in RLD, especially oversizing. Chest-Wall-Strapping (CWS) is a technique forcing the lung to operate at lower volumes. We developed a porcine model of CWS to investigate limits of oversizing. Farm-raised pigs were intubated and mechanically ventilated. Computer tomography (CT) volumetry demonstrated that Total Lung Volume (TLV) at 25 cm H2O end-expiratory pressure was 1,204 ml at baseline. Application of increasing doses of CWS reduced TLV to 879 ml (CWS-cuff inflated to 35 mm Hg) and reduced TLV to 620 ml (CWS-cuff inflated to 50 mm Hg). At 50 mm Hg of CWS (50% TLV reduction) atelectasis of the lung bases was evident. Lung elastance was increased with CWS. CT lung-density at 35 mm Hg CWS (30% reduction in TLV) was normal for the inflation state of the lung. Physiological limits of oversizing should be considered for optimal lung function.

Background:Hyperammonemia syndrome (HS) is a life-threatening complication primarily affecting lung transplant recipients (LTR). HS is strongly associated with mollicute infection. We implemented an active surveillance and prophylaxis protocol for HS in LTR. Herein, we evaluate the impact of our protocol on rates and outcomes of HS. Methods:This was a single-center retrospective cohort study of adult LTR performed from 1/1/2019 to 6/6/2024. Our surveillance and prophylaxis protocol was implemented on 8/1/2022 and included PCR testing for mollicutes on post-operative bronchoalveolar lavage samples, measurement of serum ammonia levels, and azithromycin prophylaxis. Comparisons between pre- and post-protocol implementation groups were performed. Results:151 patients received a lung transplant during the study period, 54 (35.8%) following protocol implementation. Mollicute testing was performed in 57 LTR with most tests sent after protocol implementation (87.0% vs 10.3%, p<0.0001). Ammonia levels were checked in 53.7%; however, only 24.1% had levels checked by post-operative day 3. Ten LTR (6.6%) were diagnosed with mollicute infection, six in the pre-protocol and four in the post-protocol arm, with 70% of infections due to Mycoplasma spp. All LTR received antimicrobial prophylaxis following protocol implementation. Pre-protocol, 3.1% of LTR were diagnosed with definite HS compared to 0% in the post-protocol arm, despite 4 patients being diagnosed with mollicute infection. Conclusions:Implementing a mollicute screening and prophylaxis protocol reduced cases of HS in LTR despite some LTR developing mollicute infection. Antimicrobial prophylaxis with azithromycin and doxycycline may further optimize LTR prophylaxis. Larger studies are needed to determine optimal screening and prophylaxis strategies for HS in LTR.

In this review, we discuss physiological principles that guided the management of a lung transplant for emphysema related to alpha-1-antitrypsin deficiency, where a lung allograft to thoracic cavity size mismatch occurred (donor-to-recipient predicted total lung capacity [pTLC] ratio was 0.89, donor pTLC-to-recipient actual-TLC ratio 0.62). In emphysema, the loss of lung elastic recoil and airway obstruction leads to air trapping and lung hyperinflation. Remodeling of the thoracic cavity (“barrel chest”) develops, which has implications for donor-to-recipient sizing and postoperative management of lung transplantation. We discuss the physiology of a relatively undersized allograft and the impact on chest tube, mechanical ventilation, and respiratory system mechanics management. This case also illustrates how chronic adaptations of the ventilatory pattern to advanced lung diseases are reversible and the chest cavity size can remodel back to normal after lung transplantation.

Lung transplantation is an established management strategy for advanced end-stage lung disease with the goal of restoring normal pulmonary physiology. This principle guided our management approach to the clinical challenge of a lung transplant recipient with a small chest cavity from fibrotic lung disease. Size matching should occur based on the recipient’s predicted total lung capacity, which best reflects the recipient’s normal chest cavity size. We present an instructive case that suggests that the small chest cavity size adjusts relatively quickly toward normal once the fibrotic lungs are removed, and normal allograft is implanted.

Purpose: The aim of this pilot study is to estimate prevalence of asymptomatic community respiratory viral (CRV) carriage in lung transplant (LuTx) recipients and donors at the time of transplant, and to determine if asymptomatic carriage of CRVs increases the risk of post-transplant infection, allograft rejection or mortality.

Purpose: Chronic airway colonization with Pseudomonas is associated with the development of chronic lung allograft dysfunction (CLAD) in lung transplant recipients (LTRs). Eradication efforts with inhaled and/or systemic antibiotics are common in the cystic fibrosis population. The aim of our survey is to understand current Pseudomonas eradication practices within the lung transplant population.

SESSION TITLE: Lung Pathology: Show and Tell SESSION TYPE: Case Reports PRESENTED ON: 10/08/2023 10:45 am - 11:45 am INTRODUCTION: Polyvinyl-pyrrolidone-(PVP)-based hair-grooming spray first came into widespread use in the 1950s. Bergmann et al. reported the first case of hairspray-induced lung injury in 1958, termed theusaurosis or storage disease. But by 1978, the controversy regarding the impact of chlorofluorocarbons on the Earth's ozone layer led to a ban on their use as propellants in the USA, and ever since, theusaurosis in the US is rarely reported. CASE PRESENTATION: A 60-year-old woman presented to our lung transplant clinic after experiencing four months of dyspnea on exertion with a rapidly worsening obstructive ventilatory defect. She has a past medical history of CD-30+ cutaneous non-Hodgkin's lymphoma, which was diagnosed in 1999, and remains in remission status post radiation to the left thigh and right hand. Her subacute dyspnea on exertion began 7-months prior following a viral prodrome, with rhinorrhea, nasal congestion, and cough with clear sputum. She was "out of breath" from ordinary activities with daily living (i.e., walking from the bedroom to the bathroom), a stark contrast to prior when she walked daily (>1 mile). She grew up locally in Maryland and retired from a position as the local municipal administrator. She and her husband resided in the same house for 35-years, and he reported no respiratory symptoms. Physical exam, laboratory tests, trans-thoracic echocardiography, and cancer screening showed no abnormalities. CT chest with expiratory phase demonstrated mosaicism and physiological collapse of the tracheobronchial tree with severe diffuse air trapping (Figure or video) . The most concerning was aspect of her presentation involved her rapidly declining FEV1 on her pulmonary function tests.Due to her rapidly declining lung function, our patient underwent bilateral lung transplantation. The histology of her lung explant demonstrated diffused obliterative (constrictive) bronchiolitis (figure 1), where under high power, her airways were severely stenotic or completely obliterated by subepithelial fibrosis. We observed foreign materials (linear fibers) in multiple airways with surrounding inflammation and epithelial scarring, and smooth muscle hypertrophy. The foreign materials were characteristic of polyvinyl-pyrrolidone. DISCUSSION: Today, PVP, a polymer that thickens or stiffens hairstyles, is a key ingredient in hair-grooming spray. Leftover monomers, 1-ethenyl-2-pyrrolidinone, can be found in consumer products from the polymerization process. PVP, or hairspray, exposure is determined by consumer use patterns. The average spray release time per application is 10 seconds, and approximately 10 g of spray is emitted during a spray period. The aerosol is highly respirable, with an estimated 0.03–0.4 mg of aerosol inhaled over a 5-min period following 10 sec of spraying.The majority of theusaurosis cases were characterised by histological findings of interstitial fibrosis with infiltration by mononuclear cells, diffuse uniform thickening of the alveolar septum accompanied by deposition of collagen and elastic fibres, and/or foreign body granulomas composed of cholesterin clefts surrounded by foreign-body giant cells. Radiographic findings include diffuse ground-glass opacities and/or nodular infiltrates. CONCLUSIONS: To our knowledge, we report the first case of severe and rapidly progressive hairspray-induced obliterative (constrictive) bronchiolitis, confirmed by lung explant histology of PVP within the airway lumens, associated with surrounding inflammation, collagen deposition, and fibrosis. REFERENCE #1: 1. Bergmann M, Flance IJ, Cruz PT, Klam N, Aronson PR, Joshi RA, et al. Thesaurosis due to inhalation of hair spray. New England Journal of Medicine. 1962;266(15):750–5. REFERENCE #2: 2. N-vinyl-2-pyrrolidone [Internet]. National Center for Biotechnology Information. PubChem Compound Database. U.S. National Library of Medicine; [cited 2022Aug27]. REFERENCE #3: 3. Polyquaternium-11 [Internet]. CPID. [cited 2022Aug27]. Available from: https://www.whatsinproducts.com/chemicals/view/1/882 DISCLOSURES: No disclosure on file for Michael Eberlein No relevant relationships by Kam Sing Ho No relevant relationships by Robert Reed No relevant relationships by Nevins Todd

PURPOSE:We aim to report the ECMO utilization patterns, patient characteristics, and outcomes during the COVID-19 pandemic. METHODS:We queried the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS) data for 2020 [2].We included all adults ($18-year-old) hospitalized with a diagnosis of COVID-19 using International Classification of Diseases, Tenth-Revision, Clinical Modification (ICD-10-CM) code U07.1 (sensitivity 98.01%; specificity 99.04%) and ECMO support was identified consistent with prior literature [3,4].Statistical analyses were performed using Stata 16.0 (StataCorp.2019).All reported P-values are 2-sided, with a value of <0.05 considered significant.

Optimal oxygenation in the intensive care unit requires adequate pulmonary gas exchange, oxygen-carrying capacity in the form of hemoglobin, sufficient delivery of oxygenated hemoglobin to the tissue, and an appropriate tissue oxygen demand. In this Case Study in Physiology, we describe a patient with COVID-19 whose pulmonary gas exchange and oxygen delivery were severely compromised by COVID-19 pneumonia requiring extracorporeal membrane oxygenation (ECMO) support. His clinical course was complicated by a secondary superinfection with staphylococcus aureus and sepsis. This case study is provided with two goals in mind (1) We outline how basic physiology was used to address life-threatening consequences of a novel infection-COVID-19. (2) We describe a strategy of whole-body cooling to lower the cardiac output and oxygen consumption, use of the shunt equation to optimize flow to the ECMO circuit, and transfusion to improve oxygen-carrying capacity when ECMO alone failed to provide sufficient oxygenation.

Chronic obstructive pulmonary disease (COPD) is a common lung disease characterized by limited expiratory airflow due to lung destruction or airway obstruction. Chest wall strapping (CWS) is a potential therapy technique that restricts the upper abdomen, inducing breathing at lower lung volumes and opening small airways. Although the respiratory impacts of CWS have been examined, the relationship between CWS and the cardiovascular system, which is closely tied to ventilation, has not been well-established. Additionally, COPD patients have reduced autonomic nervous system activity, which may be reflected in cardiorespiratory coupling. Cardiorespiratory coupling causes increased heart rate during inhalation to accommodate for increased blood return. The strength of this relationship was evaluated during CWS in five COPD and six control patients by analyzing heart rate changes during ventilation cycles. Heart rate and ventilatory data were collected during baseline, CWS, and post-CWS removal periods. Average heart rate during each inhalation and exhalation was plotted against tidal volume, with the slope of the linear regression representing the strength of the cardiorespiratory coupling relationship (BPM/L). Multi-factor ANOVA statistics showed a significantly diminished strength in COPD patients compared to control (p < 0.001). There was no significant change in either group post-CWS, suggesting that the same-sized breaths will cause the heart to respond similarly regardless of the total lung capacity. A potential consequence of diminished cardiorespiratory coupling in COPD patients is strain on the right side of the heart, which then has to pump larger stroke volumes. Blunted cardiorespiratory coupling is not further impaired by CWS.

A paradigm shift occurred for the treatment of irreversible end-stage lung disease when the Toronto lung transplant team achieved long-term success with a single lung transplantation (SLT).1 The first bilateral lung transplant was reported in 1988, followed shortly thereafter by the introduction of the bilateral sequential lung transplant technique (BLT).2 SLT and BLT have ever since existed as possible therapeutic options to choose between. In the absence of randomized controlled trials comparing SLT and BLT, a series of retrospective cohort studies and analyses of lung transplant registry databases provide some themes: - Compared with SLT, BLT is generally associated with longer posttransplant survival.3 - When attempting to control for possible SLT versus BLT candidate selection biases by limiting the study population to only candidates who were listed for both options, there is no appreciable survival difference between procedure.4 - In candidates with significant secondary pulmonary hypertension (SPH), SLT is associated with worse survival.3 In this edition of Transplantation, Sunagawa et al5 report on the Temple University experience with SLT in patients with severe SPH. This retrospective single-center cohort study included 318 SLT recipients who were transplanted between January 2017 and December 2019. It deserves an emphasis that most of the patients who underwent SLT in this cohort were older and did not have severe SPH at the time of listing but developed it by the time they underwent transplantation. Swan-Ganz-catheter data from the time of the lung transplant operation of the SLT candidates were used to stratify recipients into 3 groups based on mean pulmonary artery pressures (mPAP): A. No SPH (mPAP <25, n = 42) B. Mild SPH (mPAP 25–40 mm Hg, n = 219) C. Severe SPH (mPAP >40 mm Hg, n = 59) The authors report that the severe SPH group required more intraoperative cardiopulmonary support (severe SPH 37.3% versus mild SPH 10.3% versus no SPH 4.7%, P < 0.05); however, there were no significant differences in most major postoperative outcomes, including the duration of postoperative mechanical ventilation or the incidence of severe primary graft dysfunction. Furthermore, survival 1 y posttransplant was not significantly different among the groups (severe SPH 93.2% versus mild SPH 89.4% versus no SPH 92.9%, P = 0.58). Before concluding that SLT (with appropriate intraoperative mechanical circulatory support) is a comparable option for candidates with severe SPH, there are several challenges that need to be carefully addressed. In general, the type of operation (SLT versus BLT) is planned based on data during the lung transplant evaluation. The stratification of the study cohort here, however, occurred based on mPAP at the time of the operation. It is notable that, at the time of listing, the stratification of patients would have been quite different: the mPAPs at the time of listing were in group (A) 20.9 ± 5.1 mm Hg, (B) 23.3 ± 7.1 mm Hg, and (C) 26.9 ± 7.4 mm Hg, respectively. This suggests that, at time of listing, the study cohort on average had no or only mild SPH. This also highlights that, during the listing time of (A) 165.4, (B) 168.7, and (C) 136.7 d, there was a substantial increase in mPAP in groups B and C. Furthermore, assessment of right ventricular (RV) function is a critical element in the procedure planning process for both type of procedure and need for intraoperative support. In this study at the time of listing, right atrial pressures and cardiac indices were within the normal range in all cohorts, suggesting preserved RV function at that time. Although not reported by objective data, a key component in the determination of the procedural plan was the intraoperative transesophageal echocardiographic assessment of RV function. In future studies, it will be critical to determine RV function-based risk stratification tools that allow for a generalizable approach to procedural planning. In addition, clarifying comprehensive recipient and donor risk factors to allow for optimized candidate selection will be critical. Advances in extracorporeal support strategies, procedural approaches, donor to recipient matching practices (awareness of the risks associated with undersized allografts, especially in the context of pulmonary hypertension). and improvements of perioperative management strategies all could lead to a resurgence of SLT.6,7 In addition to short-term outcomes (perioperative morbidity and mortality, 1-y survival), SLT will also have to prove itself in terms of longer-term survival and patient-related outcome measures. In summary, Sunagawa et al5 from the Temple University lung transplant program should be commended for their excellence, expertise, and efforts to expand the role of SLT in the context of SPH. If these results are confirmed in future studies, the possibly expanded role of SLT could be a step in the right direction to achieve the OPTN goals of increasing the number of transplants, providing equity in access to transplants and improving waitlisted patient and transplant recipient outcomes.8

BACKGROUND:Pre-existing chronic kidney disease (CKD) may have an impact on post-lung transplant survival and the development of end stage kidney disease (ESKD). METHODS:We analyzed the US transplant database from 2006 to 2020. Adult patients who received their first lung transplant and were not on dialysis were included. Multivariable Cox regression was used to assess the effect of pretransplant eGFR on mortality and cumulative incidence competing risk was used to explore the effect on ESKD. RESULTS:The adjusted hazard ratio (aHR) for mortality showed a "U" shaped association with eGFR with a rising mortality at <60 and >100 ml/min/1.73m2. The increase in mortality with higher eGFR was only seen in those <30 year and were primarily in whites with a lower body mass index and in patients with cystic fibrosis (CF). The aHR for ESKD increased below an eGFR of 100 rising to 1.74 at an eGFR of 60. Any decrease in eGFR between listing and transplant >10% was associated with higher risk of ESKD. CONCLUSIONS:The U-shaped association of pretransplant eGFR with post-transplant mortality correlated with younger age, lower BMI and a diagnosis of CF. The aHR for ESKD following lung transplantation increased exponentially with worsening eGFR pretransplant.

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.