Obsessive-Compulsive Training Experiences in United States (US) Medical School Education Programs.

The concept of preserved ratio impaired spirometry (PRISm) was first introduced by Wan and colleagues in 2014 to classify people with an FEV₁ less than 80% of predicted or less than lower limit of normal (LLN) in the presence of a normal FEV₁/forced vital capacity (FVC) ratio (i.e., FEV₁/FVC ≥0.7 or more than LLN) in an observational study of current or former smokers aged 45-80 years with ≥10 pack-years of smoking (Wan et al. ). Since then, PRISm is a topic of increased investigation due to its significant prevalence (⁓12%) (Robertson et al. ) and association with respiratory symptoms, cardiovascular disease, metabolic syndrome and increased mortality (Wan et al. , , ; Wijnant et al. ). As corollary, the PRISm concept was first introduced in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) report in 2023 as a pre-COPD condition at risk of developing airflow obstruction over time, representing an opportunity for COPD prevention, early diagnosis and prompt therapeutic intervention (Agustí et al. a). A distinctive feature of PRISm that has gained attention is the greater exertional dyspnoea and lower exercise capacity (Phillips et al. ), physical performance (Anami et al. ), more frequent respiratory symptoms and poorer quality of life (Zhou et al. ). It was shown that exercise performance was mainly influenced by the magnitude of prevailing inspiratory mechanical constraints, regardless of sex, body mass index, FEV and resting gas exchange capacity (diffusing capacity of the lungs for carbon monoxide; DL). It means that, because of a lower FVC and inspiratory capacity (IC) at rest, constraints for further tidal volume (VT) expansion was met at lower workload and ventilation compared to healthy controls (Phillips et al. ). With progressively higher VT/IC ratios at low workloads, the VT becomes positioned at the upper less compliant portion of the respiratory system’s pressure–volume relationship. Even at relatively light-to-moderate exercise, elastic loading of the inspiratory muscles and inspiratory neural drive may increase to high levels to sustain ventilation commensurate with metabolic requirements (Faisal et al. ; James et al. ). The excessive inspiratory neural drive is associated with higher dyspnoea at relatively low ventilation (Faisal et al. ; James et al. ; Jolley et al. ; Schaeffer et al. ), even in symptomatic smokers without (Elbehairy et al. ) or just with mild COPD (Guenette et al. ). However, a significant heterogeneity in the definitions and nomenclature used for impaired lung function characterized by proportionate reductions in FEV and FVC exists. It has also been described as restrictive (Backman et al. ; Guerra et al. ; Mannino et al. ), non-specific (Hyatt et al. ; Iyer et al. ), or unclassified spirometry (Wan et al. ). Accordingly, a variety of different conditions, including some with ominous prognosis, have been reported to be associated with this pattern (Godfrey & Jankowich ; Stanojevic et al. ). Not surprisingly, there are a plenty number of population-based epidemiological studies (Cadham et al. ; Higbee et al. ; Wallström et al. ; Wan et al. ) linking the PRISm pattern with increased rates of hospitalization and mortality. They should be viewed with caution, however, since concomitant comorbidities may have caused the PRISm pattern, or that this pattern, in fact, represented an actual restrictive ventilatory defect (i.e., total lung capacity (TLC) < lower limit of normal (LLN)) (Knox-Brown et al. ). Accordingly, among the 59 patients in the main study exploring the mechanisms underpinning dyspnoea and exercise intolerance in patients with PRISm (Phillips et al. ), nine (15%) presented with restriction. Furthermore, the 20 never-smokers (representing 1/3 of the sample) showed similar lung structure, resting pulmonary function and exercise characteristics to the 39 ever-smokers (including 16 active smokers), suggesting no effect of smoking history on lung function within the PRISm group and raising the concern about an undetected significant pathophysiological comorbidity in these subjects.