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What is already known: Alongside age, pre-existing medical conditions are perceived negatively during triage assessments, particularly if rare, and/or theoretically expected to influence cardiorespiratory risk; Anaesthetists use cardiopulmonary exercise testing to categorise patients to higher and lower risk independently to diagnostic labels, but this is not feasible in acute settings; Pulmonary arteriovenous malformations are an exemplar of a condition where, due to expected or measured abnormalities (hypoxaemia-low PaO2 SpO2), poor physiological capacity might be predicted.
What this study adds Neither age nor usual SpO2 predicted lower/higher risk categories by anaerobic threshold, but haemoglobin-dependent indices of oxygen delivery to the tissues were associated with higher risk, offering opportunities for improvement by attention to anaemia and aerobic conditioning; Baseline exercise tolerance may override age and diagnostic labels in triage settings: the 13point VSAQ Veterans Specific Activity Questionnaire (VSAQ) is suggested as a rapid screening tool for cardiorespiratory risk assessment.Abstract 1 2 BACKGROUND: Rapid triaging, as in the current COVID-19 pandemic, focuses on age and pre-existing 3 medical conditions. In contrast, preoperative assessments use cardiopulmonary exercise testing (CPET) 4 to categorise patients to higher and lower risk independent of diagnostic labels. Since CPET is not 5 feasible in population-based settings, our aims included evaluation of a triage/screening tool for 6 cardiorespiratory risk. 7 METHODS: CPET-derived anaerobic thresholds were evaluated retrospectively in 26 patients with 8 pulmonary arteriovenous malformations (AVMs) who represent a challenging group to risk-categorise. 9 Pulmonary AVM-induced hypoxaemia secondary to intrapulmonary right-to-left shunts, anaemia from 10 underlying hereditary haemorrhagic telangiectasia and metabolic equivalents derived from the 13-point 11 Veterans Specific Activity Questionnaire (VSAQ) were evaluated as part of routine clinical care. Pre-12 planned analyses evaluated associations and modelling of the anaerobic threshold and patient-specific 13 variables. 14 RESULTS: In the 26 patients (aged 21-77, median 57 years), anaerobic threshold ranged from 7.6-24.5 15 (median 12.35) ml.min -1 kg -1 and placed more than half of the patients (15, 57.7%) in the >11 ml.min -16 1 kg -1 category suggested as "lower-risk" for intra-abdominal surgeries. Neither age nor baseline SpO2 17 predicted anaerobic threshold, or lower/higher risk categories, either alone or in multivariate analyses, 18 despite baseline oxygen saturation (SpO2) ranging from 79 to 99 (median 92)%, haemoglobin from 108 19 to 183 (median 156)g.L -1 . However, lower haemoglobin, and particularly, arterial oxygen content and 20 oxygen pulse were associated with increased cardiorespiratory risk: Modelling a haemoglobin increase 21 of 25g.L -1 placed a further 7/26 (26.9%) patients in a lower ...