Subjective assessment underestimates surgical risk: On the potential benefits of cardiopulmonary exercise testing for open thoracoabdominal repair.

BACKGROUND: Initial clinical evaluation (ICE) is traditionally considered a useful screening tool to identify frail patients during the preoperative assessment. However, emerging evidence supports the more objective assessment of cardiorespiratory fitness (CRF) via cardiopulmonary exercise testing (CPET) to improve surgical risk stratification. Herein, we compared both subjective and objective assessment approaches to highlight the interpretive idiosyncrasies. METHODS: As part of routine preoperative patient contact, patients scheduled for major surgery were prospectively "eyeballed" (ICE) by two experienced clinicians before more detailed history taking that also included the American Society of Anesthesiologists score classification. Each patient was subjectively judged to be either "frail" or "not frail" by ICE and "fit" or "unfit" from a thorough review of the medical notes. Subjective data were compared against the more objective validated assessment of postoperative outcomes using established CPET "cut-off" metrics incorporating peak pulmonary oxygen uptake, V̇O2PEAK at the anaerobic threshold (V̇O2 -AT), and ventilatory equivalent for carbon dioxide that collectively informed risk stratification. These data were retrospectively extracted from a single-center prospective National Health Service database. Data were analyzed using the Chi-square automatic interaction detection decision tree method. RESULTS: A total of 127 patients were examined that comprised 58% male and 42% female patients aged 69 ± 10 years with a body mass index of 29 ± 7 kg/m2 . Patients were poorly conditioned with a V̇O2PEAK almost 20% lower than predicted for age, sex-matched healthy controls with 35% exhibiting a V̇O2 -AT < 11 ml/kg/min. Disagreement existed between the subjective assessments of risk with ∼34% of patients classified as not frail on ICE were considered unfit by notes review (p < .0001). Furthermore, ∼35% of patients considered not frail on ICE and ∼31% of patients considered fit by notes review exhibited a V̇O2 -AT < 11 ml/kg/min, and of these, ∼28% and ∼19% were classified as intermediate to high risk. CONCLUSIONS: These findings highlight the interpretive limitations associated with the subjective assessment of patient frailty with surgical risk classification underestimated in up to a third of patients compared to the validated assessment of CRF. They reinforce the benefits of a more objective and integrated approach offered by CPET that may help us to improve perioperative risk assessment and better direct critical care provision in patients scheduled for "high-stakes" surgery including open thoracoabdominal aortic aneurysm repair.

A pilot study of the mental workload of objective structured clinical examination examiners.

CONTEXT: Mental workload is a concept used in many industries to investigate operator performance, but it has only recently been used in the educational setting. It has been suggested that excessive mental workload in assessors may impair the validity of objective structured clinical examination (OSCE)-type assessments. OBJECTIVES: This study aimed to establish the feasibility of measuring the mental workload of examiners during an OSCE assessment and to establish methodologies and baseline values to guide future study design. METHODS: Two previously validated methods of measuring mental workload, the NASA-Task Load Index rating scale and use of a secondary task (response to a prompt from a vibrotactile device), were used to measure the workload of 10 subjects during a formative OSCE. Trainee anaesthetists (n = 24) working in an operating theatre were used as a control group. RESULTS: The mental workload of examiners exceeded that of controls on both measures. Although there was marked inter-subject variability, reliability between stations for individual examiners was robust (α = 0.922). CONCLUSIONS: These data suggest that mental workload is excessive in OSCE examiners. Further studies are required to measure the effect of changes in assessment design and examiner training.