Validation of preoperative cardiopulmonary exercise testing-derived variables to predict in-hospital morbidity after major colorectal surgery.

British Journal of Surgery. West MA, Asher R et al. 2017;103: 744–752

Presented by Dr L. Emmett

Background

  • Major colorectal surgery carries substantial morbidity and mortality – 30 day mortality of 2.9%
  • Risk stratification permits collaborative decision making, optimisation and effective utilisation of hospital resources
  • CPET is an objective measure of physical fitness under stress, mimicking surgery
  • This study aimed to assess the predictive value of selected CPET variables and their association with in-hospital morbidity in major elective colorectal surgery

Methods

  • 6 UK hospitals recruited consecutive adult patients over a 3 year period

Inclusion criteria

  • Major elective colorectal surgery

Exclusion criteria

  • Emergency surgery
  • Neoadjuvant chemotherapy
  • Lower limb dysfunction
  • Inability to consent
  • Inflammatory bowel disease
  • Distant metastases

 

  • CPET was conducted according to American Thoracic Society and American College of Chest Physician guidelines
  • Standard protocols used for all patients – observations recorded were heart rate, 12 lead ECG, blood pressure and pulse oximetry. Ventilation and gas exchange were monitored using a metabolic cart
  • In-hospital morbidity was measured at 5 days post op using an objective scoring system, Dindo score and post op 30 day mortality were also recorded

Primary aim

  • Compare the postoperative morbidity score and the V02 at lactate threshold and peak exercise

Secondary aims

  • To compare multi variable relationship between patient demographics, CPET variables and post operative in hospital morbidity

Intervention

  • Statistical analysis of CPET variables matched with POMS tool
  • 425 patients to be recruited to demonstrate that these variables were better than chance at risk prediction

Results

  • 7% had postoperative complications
  • VO2 lactate threshold <11.1ml/kg/min and VO2 peak threshold <18.2ml/kg/min were associated with a statistically significant increase in post operative complications
  • BMI >27 and open procedures (rather than laparoscopic) associated with increased complications

Conclusions

  • There was a statistically significant increase in postoperative morbidity in those patients with a lower VO2 at lactate threshold, VO2 at peak, and O2 pulse at lactate threshold

Strengths

  • Conclusion matches primary aim
  • More evidence that CPET testing is valuable, potentially selecting appropriate patients and risk stratifying
  • Potential for increasing CPET provision, funding and awareness
  • No adverse effects
  • Strong statistical significant observed
  • In keeping with findings from other studies

Weaknesses

  • No new knowledge, only backing up existing evidence
  • Unblinded study, CPET data used in clinical management
  • Centre to centre variations in findings
  • CPET isn’t the whole story!

Implications and Potential for Impact

  • Further increasing evidence base
  • Increase provision of CPET services
  • Stimulate further research in high risk patients
  • Asks questions about utilisation with other risk scoring systems