ARISCAT Score for Postoperative Pulmonary Complications

• ARISCAT should be interpreted within the broader clinical context, including functional status, frailty, and psychosocial factors, especially prior to instituting mitigation strategies based on risk subtype
• Geographic variation in performance was seen in the literature, this score is best calibrated for Western European populations. Limited U.S-specific validation studies should warrant caution when applying to North American populations. 
• In the PERISCOPE validation study, there was a noted fall in calibration slope from 0.81 in Western Europe to 0.58 in Eastern Europe (Mazo et al. 2014).

Low-risk patients (<26)

• Standard perioperative care including early mobilization, adequate analgesia to facilitate deep breathing and minimize atelectasis, incentive spirometry, basic chest physiotherapy.

Intermediate-risk patients (26-44)

• All low-risk interventions plus preoperative optimization via smoking cessation, treatment of pulmonary comorbidities, and correction of anemia. 

• Intraoperatively, consider recruitment maneuvers, careful use of paralytics with full reversal, and conservative fluid administration to avoid pulmonary edema. 

• Postoperatively, consider aggressive pulmonary hygiene with incentive spirometry/chest physiotherapy, regional techniques to minimize opioids, and admission to step-down unit if patient has marginal reserve.

High-risk (>45)

• All low/intermediate risk interventions plus consideration of inspiratory muscle training programs and optimization of comorbidities. 

• Intraoperatively, avoid high driving pressures and minimize time spent under general anesthesia. 

• Postoperatively, consider early institution of respiratory support (CPAP or BiPAP) along with vigilant ICU monitoring in case reintubation is required. 

Other Considerations

Lung-protective ventilation with low tidal volumes (6-8mL/kg predicted body weight) combined with moderate/high PEEP has been shown to reduce incidence of post-operative pulmonary complications in broader surgical populations and should generally be viewed as standard of care. 

In certain patients, individualized PEEP strategies may offer additional benefit compared to a fixed PEEP level. 

The iPROVE-OLV trial found that PEEP titration to optimal lung compliance reduced postoperative pulmonary complications compared to standard protective ventilation in patients undergoing thoracic surgery (Ferrando et al. 2024). 

Inspiratory muscle training (IMT) is also a high yield intervention if instituted 2-8 weeks before surgery, particularly in patients with a higher baseline risk. The program usually consists of breathing exercises against resistance using a threshold inspiratory muscle trainer. 

Daily sessions are usually 15-30min and are done during the several weeks prior to surgery. A meta-analysis found that implementation of an IMT program reduces complications by 50% and shortens hospital length of stay by one day (Katsura et al. 2015). Specifically, high-risk patients derived the greatest benefit. Intermediate/low-risk patients also may benefit from IMT but the evidence is less substantial in these risk strata.

• ARISCAT score only addresses risk of pulmonary complications and does not serve as a comprehensive perioperative assessment tool.
• Care should be taken to evaluate bleeding, thrombotic, cardiovascular, and procedure-specific risks simultaneously as these may take precedence over pulmonary optimization. 
• Two specific situations that may alter pulmonary risk include:
  • Active pulmonary infection: Consider postponing surgery.
    • Active respiratory infection with fever only adds 17 points to the ARISCAT but may underestimate overall pulmonary risk in this context.
  • Hypoalbuminemia: Consider nutritional optimization.
    • An important predictor of post-operative pulmonary complications and should trigger increased vigilance in the perioperative period.