Recommendations from The Medical Education Editor

proceeded to surgery, with the majority having lobar resections. Scalene muscle hyperactivity was inversely correlated with FEV1 and positively correlated with total lung capac-ity. In those patients who also underwent cardiopulmonary exercise testing, the patients with RMH also had lower VO 2 max. After accounting for FEV1, a finding of RMH was associated with a poorer prognosis (Figure 1). A nested Cox proportional hazards model using the Charlson Comorbidity Score (CCS), FEV1 and RMH predicted post-operative survival more effectively than a model using CCS alone. The authors suggest a potential role for assessing RMH in patients with chronic respiratory disease, not only in eval-uating pre-operative patients planned for lung cancer resection. This would require further research examining the relationship between specific conditions and muscle activation patterns, and normative data for SUVm in respiratory muscles. However, PET scanning for this purpose is appeal-ing due to its non-invasive nature and relative availability, especially if other studies confirm an association with patient outcomes

In the April issue of Respirology, Guo et al. reported their analysis of a survey of almost 10,000 Australian adults regarding their medical conditions and the perception of dyspnoea. 4 Breathlessness was defined as having a modified Medical Research Council (mMRC) dyspnoea scale grade ≥2, and participants reported their height, weight, age and comorbid illnesses. Fifty-one percent of participants were female, 28% were obese, 16% reported daily smoking and the prevalence of breathlessness was just below 10%. Comorbidities reported included asthma, chronic obstructive pulmonary disease (COPD), back pain, arthritis, ischaemic heart disease, anxiety and depression. The authors estimated the population attributable fraction to determine 'the proportion of breathlessness in the population that would be reduced if the risk factor, obesity, was eliminated'. 4 Obese patients were twice as likely to report breathlessness after adjustment for age, and the adjusted population attributable fraction (aPAF) of obesity for breathlessness was 24% for women and 19% for men. When adjusted for each comorbid condition listed, the aPAF of obesity remained between 20% and 25%.
These findings have implications for health planning, medical education and the clinician sitting with an individual patient in the clinic. This paper adds weight to the argument that obesity treatment should be considered for patients with dyspnoea, in addition to the many other situations in which it is important.
A diagnosis of airway hyperresponsiveness (AHR) at bronchoprovocation testing can be critical in a patient presenting with suspected asthma, chronic cough or unexplained dyspnoea. Traditionally, bronchoprovocation testing has relied on changes in the forced expiratory volume in 1 second (FEV1) as a marker of bronchoconstriction in response to the provoking agent. 5 However, it is plausible that other lung function parameters might provide further helpful information about the airway response.
In the May issue of Respirology, Parker et al. reported the findings of their study of the utility of specific airway conductance (sGaw) as a response variable in direct bronchoprovocation tests using methacholine. 6 They reviewed the results of 211 challenge tests from a random selection of 300, with 89 excluded due to missing data. Their cohort had a mean age of 53 years, 67% were female, the median BMI was 29 kg/m 2 , and 38% were current or former smokers. Baseline lung function results were normal. A provocative concentration causing a 20% reduction in FEV1 (PC20) < 8 mg/mL was used as the cut-off and PC40 < 8 mg/mL for sGaw.
Patients were separated into four groups according to their methacholine responsiveness: no AHR (neither PC20 for FEV1 or PC40 for sGaw were met), met the FEV1 criterion but not sGaw, met sGaw criterion but not FEV1, or met both criteria. The majority (94%) of patients who met the PC20 FEV1 criterion also met the P40 sGaw criterion, while many more patients met the PC40 sGaw criterion without meeting the PC20 FEV1 criterion, suggesting a possible increase in sensitivity for sGaw in AHR. Of the patients who met the PC40 criterion for sGaw but not the PC20 criterion for FEV1, 93% of them were subsequently diagnosed with asthma.
These findings suggest the need for ongoing research and evaluation of the physiologic responses to bronchoprovocation testing and that we might need to consider broadening our definition of a positive bronchoprovocation test in future years.
Assessment of respiratory muscle activity in patients with chronic respiratory disease is limited by availability and expertise; however, it is conceivable that patients with higher respiratory muscle activity might present with different symptoms and suffer worse outcomes. For example, the association between dyspnoea and increased diaphragmatic activation suggests a potential therapeutic target in patients with COPD. 7 In the June issue of Respirology, El Husseini et al. reported on using 18F-FDG/PET-CT to assess for respiratory muscle hypermetabolism (RMH) in patients being planned for surgical resection of early-stage lung cancer. 8 Their analysis included 156 patients over 5 years, of whom 71% were male, and 46% had known lung disease. Respiratory muscle group maximum Standardized Uptake Values (SUVm) were obtained from pre-operative PET scans, and 45 patients (29%) were diagnosed with RMH. All patients proceeded to surgery, with the majority having lobar resections.
Scalene muscle hyperactivity was inversely correlated with FEV1 and positively correlated with total lung capacity. In those patients who also underwent cardiopulmonary exercise testing, the patients with RMH also had lower VO 2 max. After accounting for FEV1, a finding of RMH was associated with a poorer prognosis (Figure 1). A nested Cox proportional hazards model using the Charlson Comorbidity Score (CCS), FEV1 and RMH predicted postoperative survival more effectively than a model using CCS alone.
The authors suggest a potential role for assessing RMH in patients with chronic respiratory disease, not only in evaluating pre-operative patients planned for lung cancer resection. This would require further research examining the relationship between specific conditions and muscle activation patterns, and normative data for SUVm in respiratory muscles. However, PET scanning for this purpose is appealing due to its non-invasive nature and relative availability, especially if other studies confirm an association with patient outcomes.
KEYWORDS clinical teaching, continued medical education, professional development, training programme