/study / lectures / Pre-anesthesia
Pulmonary Risk — ARISCAT Score + Postop Pulmonary Complications
TEXTPre-anesthesia · 6 min read
Postoperative pulmonary complications match cardiac events for mortality impact + LOS — and most are preventable. ARISCAT identifies who, lung-protective ventilation + multimodal analgesia change outcomes.
After this lesson you can
3 min read6 sectionsARISCAT score (Canet, Anesthesiology 2010)
10 g/dL (11)- low (<26 points, 1.6% PPC)
- intermediate (26-44, 13%)
- high (≥45, 42%)
Validated in PERISCOPE (Mazo, Anesthesiology 2014).
Use it to triage who gets preop pulmonary optimization + intensified intraop strategies.
Modifiable preop factors
Within 12-24 hours: carboxyhemoglobin drops, mucociliary function improves.
4-8 weeks: PPC rate falls.
Brief cessation (<2 weeks) does NOT reliably reduce complications — and historical 'paradox' studies suggesting harm have been refuted (Myers 2011 meta-analysis: brief cessation safe + neutral, longer cessation beneficial).
Optimize COPD: ensure bronchodilator + inhaled corticosteroid use, consider 5-day course of oral prednisone for exacerbating COPD.
Optimize asthma: peak flow >80% personal best before elective surgery, continue inhalers including day-of.
Treat any active respiratory infection — defer elective surgery 4-6 weeks after URI in adults, 2-4 weeks in children.
Intraop lung-protective ventilation
6-8 mL/kg predicted body weight (PBW: men 50 + 0.91× (cm-152.4); women 45.5 + 0.91× (cm-152.4)) — NOT actual body weight, NOT ideal body weight per old formulas.PEEP 5-10 cmH₂O routinely; higher in obesity, lower if hemodynamically tenuous.
Recruitment maneuvers (30-40 cmH₂O × 30 sec, or stepwise) after intubation + after disconnections, repeated periodically — abolish atelectasis that develops from FiO₂ + paralysis.
Plateau pressure <16-18 cmH₂O when achievable; driving pressure (Pplat - PEEP) <13 cmH₂O is the most robust predictor of PPC (Neto IMPROVE 2015).
FiO₂ titrated to lowest that maintains SpO₂ >92% — supraphysiologic O₂ does NOT reduce SSI + increases atelectasis.
Analgesia + reducing opioids
Multimodal: regional/neuraxial when feasible (thoracic epidural for thoracotomy, paravertebral or ESP for breast + thorax, TAP for abdominal, adductor canal + IPACK for knee).
Acetaminophen scheduled.
NSAIDs unless contraindicated (avoid in active GI bleeding, severe CKD, certain CV concerns).
Gabapentinoids only in selected patients — sedation risk in elderly.
Ketamine 0.1-0.3 mg/kg/hr infusion useful in opioid-tolerant.
- enable cough
- deep breathing
- ambulation by POD0-1
Postoperative bundle
Incentive spirometry — patient-performed q1h while awake; weak evidence as standalone but reinforces deep breathing.
Early ambulation POD0 if surgery allows.
CPAP/BIPAP empirically continued in OSA patients postop — bring their home machine, apply in PACU.
Chest physiotherapy + airway clearance for COPD, bronchiectasis, neuromuscular disease.
Aggressive secretion management (suction, humidification).
Reverse residual neuromuscular blockade to TOF ratio >0.9 — incomplete reversal is a major predictor of PPC (POPULAR study Lancet 2019).
OSA + obesity-hypoventilation
Score ≥3 = high risk OSA.
ASA OSA Practice Guidelines: continue home CPAP perioperatively.
Avoid long-acting opioids when possible.
Extended PACU observation.
Obesity-hypoventilation syndrome (OHS, daytime hypercapnia + BMI >30) carries higher PPC + mortality than simple OSA — preop ABG if suspected, bi-level positive airway pressure home setup confirmed.
End of lecture
You just covered ~3 minutes of Pre-anesthesia. Reinforce with a few questions while it's fresh.