Development and external validation of preoperative clinical prediction models for postoperative outcomes including preoperative aerobic fitness in patients approaching elective colorectal cancer surgery.

INTRODUCTION: Preoperative aerobic fitness is associated with postoperative outcomes after elective colorectal cancer (CRC) surgery. This study aimed to develop and externally validate two clinical prediction models incorporating a practical test to assess preoperative aerobic fitness to distinguish between patients with and without an increased risk for 1) postoperative complications and 2) a prolonged time to in-hospital recovery of physical functioning after elective colorectal cancer (CRC) surgery. MATERIALS AND METHODS: Models were developed using prospective data from 256 patients and externally validated using prospective data of 291 patients. Postoperative complications were classified according to Clavien-Dindo. The modified Iowa level of assistance scale (mILAS) was used to determine time to postoperative in-hospital physical recovery. Aerobic fitness, age, sex, body mass index, American Society of Anesthesiologists (ASA) classification, neoadjuvant treatment, surgical approach, tumour location, and preoperative haemoglobin level were potential predictors. Areas under the curve (AUC), calibration plots, and Hosmer-Lemeshow tests evaluated predictive performance. RESULTS: Aerobic fitness, sex, age, ASA, tumour location, and surgical approach were included in the final models. External validation of the model for complications and postoperative recovery presented moderate to fair discrimination (AUC 0.666 (0.598-0.733) and 0.722 (0.651-0.794), respectively) and good calibration. High sensitivity and high negative predictive values were observed in the lower predicted risk categories (<40 %). CONCLUSION: Both models identify patients with and without an increased risk of complications or a prolonged time to in-hospital physical recovery. They might be used for improving patient-tailored preoperative risk assessment and targeted and cost-effective application of prehabilitation interventions.

Feasibility of Exercise Testing in Patients Who Are Critically Ill: A Prospective, Observational Multicenter Study.

OBJECTIVE: To evaluate the feasibility and safety of exercise testing and to describe the physiological response to exercise of patients in the Intensive Care Unit (ICU). DESIGN: A prospective observational multicenter study. SETTING: Two mixed medical-surgical ICUs. PARTICIPANTS: Patients (N=37; with no primary neurological disorders, 59% men; median age 50y; ICU length of stay 14.5d; Acute Physiology and Chronic Health Evaluation IV 73.0) who had been mechanically ventilated for more than 48 hours and were hemodynamically stable enough to perform physical exercise. INTERVENTIONS: A passive or active incremental exercise test, depending on muscle strength, on a bed-based cycle ergometer. MAIN OUTCOME MEASURES: Feasibility and safety were evaluated based on protocol adherence and adverse events. Physiological responses to exercise quantified as changes in respiratory frequency (RF), oxygen uptake (Vo2), carbon dioxide output (Vco2), respiratory exchange ratio (RER), and blood lactate. RESULTS: Thirty-seven patients of whom 18 were mechanically ventilated underwent the exercise test. The active incremental test was performed by 28, and the passive test by 9 participants. Thirty-three (89%) accomplished the test according to the protocol and 1 moderate severe adverse event (bradycardia; heart rate 44) occurred shortly after the test. RF, Vo2, Vco2, and lactate increased significantly, whereas RER did not change during the active incremental exercise test. No changes were observed during the passive exercise test. CONCLUSIONS: It is safe and feasible to perform exercise testing on a bed-based cycle ergometer in patients who are critically ill and a physiological response could be measured. Future research should investigate the clinical value of exercise testing in daily ICU practice and whether exercise capacity and its limiting factors could be determined by incremental exercise testing.