A conscious individual, as defined in the Oxford English Dictionary, is 'awake and aware of their surroundings and identity'. However, consciousness represents a continuum with varying depths of consciousness. Coma is derived from the Greek 'koma' meaning a state of sleep; more specifically, it is defined medically as 'a state of unresponsiveness from which the patient cannot be aroused'. By convention we use the Glasgow coma scale (GCS) to provide a rapid, reproducible quantification of depth of unconsciousness. Although the GCS was developed for assessment and prediction of outcome in traumatic brain injury, it remains a useful tool to assess conscious state regardless of the causative factor. The GCS scores verbal, movement and visual responses to stimulation; a GCS <8 defines coma.

Patients walking >563 m in the 6MWT do not routinely require CPET; those walking <427 m should be referred for further evaluation. In situations of 'clinical uncertainty' (≥427 but ≤563 m), the number of clinical risk factors and magnitude of surgery should be incorporated into the decision-making process. The 6MWT is a useful clinical tool to screen and risk stratify patients in departments where CPET is unavailable.

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Introduction Operable oesophagogastric adenocarcinoma management in the UK includes three cycles of neoadjuvant chemotherapy (NAC) followed by resection. Determination of oxygen uptake at the anaerobic threshold (AT) with cardiopulmonary exercise testing (CPET) is used to objectively measure cardiorespiratory reserve. Oxygen uptake at AT predicts perioperative risk, with low values associated with increased morbidity. Previous studies indicate NAC may have a detrimental impact on cardiorespiratory reserve. Methods CPET was completed by 30 patients before and after a standardised NAC protocol. The ventilatory AT was determined using the V-slope method, and the peak oxygen uptake and ventilatory equivalents for carbon dioxide measured. Median AT before and after chemotherapy was compared using a paired Student’s t-test. Results Median oxygen uptake at AT pre- and post-NAC was 13.9±3.1 ml/kg/min and 11.5±2.0 ml/kg/min, respectively. The mean decrease was 2.4 ml/kg/min (95% confidence interval [CI] 1.3–3.85; p<0.001). Median peak oxygen delivery also decreased by 2.17 ml/kg/min (95% CI 1.02–3.84; p=0.001) after NAC. Ventilatory equivalents were unchanged. Conclusions This reduction in AT objectively quantifies a decrease in cardiorespiratory reserve after NAC. Patients with lower cardiorespiratory reserve have increased postoperative morbidity and mortality. Preventing this decrease in cardiorespiratory reserve during chemotherapy, or optimising the timing of surgical resection after recovery of AT, may allow perioperative risk-reduction.

Oesophagectomy is a technically-demanding operation associated with a high level of morbidity. We analysed the association of pre-operative variables, including those from cardiopulmonary exercise testing, with complications (logistic regression) and survival and length of stay (Cox regression) after scheduled transthoracic oesophagectomy in 273 adults, in isolation and on multivariate testing (maximum Akaike information criterion). On multivariate analysis, any postoperative complication was associated with ventilatory equivalents for carbon dioxide, odds ratio (95%CI) 1.088 (1.02-1.17), p = 0.018. Cardiorespiratory complications were associated with FEV and pre-operative background survival (in an analogous group without cancer), odds ratios (95%CI) 0.55 (0.37-0.80), p = 0.002 and 0.89 (0.82-0.96), p = 0.004, respectively. Survival was associated with the ratio of expected-to-observed ventilatory equivalents for carbon dioxide and predicted postoperative survival, hazard ratios (95%CI) 0.17 (0.03-0.91), p = 0.039 and 0.96 (0.90-1.01), p = 0.076. Length of hospital stay was associated with FVC, hazard ratio (95%CI) 1.38 (1.17-1.63), p < 0.0001.

There was a decrease in cardiorespiratory reserve immediately after neoadjuvant chemotherapy that was sustained up to the point of surgery at 4 weeks after chemotherapy.

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