IHS is a rare but often fatal complication that primarily affects lung transplant recipients within the first 30 days.

S ize mismatch between donor lungs and a recipient thorax could affect the major determinants of maximal expiratory airfl ow: airway resistance, propensity of airways to collapse, and lung elastic recoil. 1 The degree of mismatch can be estimated by the ratio of predicted total lung capacities (pTLCs), using the following formula: pTLC ratio 5 donor pTLC / recipient pTLC. [2][3][4] In a previous study, a fl ow volume loop (FVL) pattern in patients who received bilateral lung transplants (BLTs) that was characterized by supranormal expiratory airfl ow (SUPRA pattern) was associated with high pTLC ratios (likely the result of oversized allografts). 5 Although patients with and without the SUPRA pattern had comparable FVC and FEV 1 , expressed as % predicted for the recipient, there were signifi cant differences in expiratory airfl ow (FEV 1 /FVC ratios and time constant estimates for lung emptying). A mismatch of oversized transplanted Background: Size mismatch between donor lungs and a recipient thorax could affect the major determinants of maximal expiratory airfl ow: airway resistance, propensity of airways to collapse, and lung elastic recoil. Methods: A retrospective review of 159 adults who received bilateral lung transplants was performed. The predicted total lung capacity (pTLC) for donors and recipients was calculated based on sex and height. Size matching was represented using the following formula: pTLC ratio 5 donor pTLC / recipient pTLC. Patients were grouped according to those with a pTLC ratio . 1.0 (oversized) or those with a pTLC ratio Յ 1.0 (undersized). Allograft function was analyzed in relation to the pTLC ratio and to recipient and donor predicted function. Results: The 96 patients in the oversized cohort had a mean pTLC ratio of 1.16 Ϯ 0.13 vs 0.89 Ϯ 0.09 in the 63 patients of the undersized group. At 1 to 6 months posttransplant, the patients in the oversized cohort had higher FEV 1 /FVC ratios (0.895 Ϯ 0.13 vs 0.821 Ϯ 0.13, P , .01) and lower time constant estimates of lung emptying (0.38 Ϯ 0.2 vs 0.64 Ϯ 0.4, P , .01) than patients in the undersized cohort. Although the FVCs expressed as % predicted for the recipient were not different between cohorts, the FVCs expressed as % predicted for the donor organ were lower in the oversized cohort compared with the undersized cohort (at 1-6 months, 52.4% Ϯ 17.1% vs 65.3% Ϯ 18.3%, P , .001). Kaplan-Meier estimates for the occurrence of bronchiolitis obliterans syndrome (BOS) showed that patients in the oversized cohort had a lower probability of BOS ( P , .001). Conclusions: A pTLC ratio . 1.0, suggestive of an oversized allograft, is associated with higher expiratory airfl ow capacity and a less frequent occurrence of BOS.

BACKGROUND: Spirometry results can yield a diagnosis of normal air flow, air flow obstruction, or preserved ratio impaired spirometry (PRISm), defined as a reduced FEV 1 or FVC in the setting of preserved FEV 1 /FVC. Previous studies have estimated the prevalence of PRISm to be 7-12%. Our objective was to examine the prevalence of PRISm in a spirometry database and to identify factors associated with PRISm. METHODS: We performed a retrospective analysis of 21,870 spirometries; 1,616 were excluded because of missing data or extremes of age, height, or weight. We calculated the prevalence of PRISm in prebronchodilator and postbronchodilator pulmonary function tests. Subsequently, we calculated the prevalence of PRISm by various age, race, body mass index, and diagnosis categories, as well as by gender and smokers versus nonsmokers. Finally, in the subset of the cohort with FEV 1 < lower limit of normal, we performed a multivariable logistic regression analysis to identify factors associated with PRISm. RESULTS: We identified 18,059 prebronchodilator spirometries, and 22.3% of these yielded a PRISm diagnosis. This prevalence remained stable in postbronchodilator spirometries (17.7%), after excluding earlier pulmonary function tests for subjects with multiple pulmonary function tests (20.7% in prebronchodilator and 24.3% in postbronchodilator), and when we limited the analysis to prebronchodilator spirometries that met American Thoracic Society criteria (20.6%). The PRISm prevalence was higher in subjects 45-60 y old (24.4%) and in males (23.7%) versus females (17.9%). The prevalence rose with body mass index and was higher for those with a referral diagnosis of restrictive lung disease (50%). PRISm prevalence was similar between races and smokers versus nonsmokers. In a multivariable analysis, higher % of predicted FEV 1 (odds ratio 1.51, 95% CI 1.42-1.60), body mass index (odds ratio 1.52, 95% CI 1.39-1.68), and restrictive lung disease (odds ratio 4.32, 95% CI 2.54-7.57) were associated with a diagnosis of PRISm. Smoking was inversely associated (odds ratio 0.55, 95% CI 0.46-0.65) with PRISm. CONCLUSIONS: In a spirometry database at an academic medical center, the PRISm prevalence was 17-24%, which is higher than previously reported.

BACKGROUND-Donor to recipient lung size matching at lung transplantation (LTx) can be estimated by the predicted total lung capacity (pTLC)ratio (donor pTLC/recipient pTLC). We aimed to determine whether the pTLC-ratio is associated with the risk of primary graft dysfunction (PGD) after bilateral LTx (BLT).

A 27-year-old female presented at 23 weeks 6 days gestation that tested positive for the coronavirus disease 2019 (COVID-19). Despite mechanical ventilation and paralysis, she remained hypoxic and was emergently cannulated for veno-venous extracorporeal membrane oxygenation (VV ECMO). The patient ambulated while intubated and on VV ECMO. She was decannulated and extubated. An ultrasound demonstrated an appropriately grown fetus without abnormalities. She was discharged to home and gave birth to a healthy baby girl at 39 weeks gestation. Utilizing VV ECMO, this patient and her fetus survived acute hypoxemic respiratory failure due to COVID-19.