Perioperative Pulmonary Management
Understand postoperative pulmonary complications — ARISCAT risk factors, ABG interpretation, and clinical strategies to reduce PPC incidence.
Try the tool first
Estimate postoperative pulmonary complication risk with ARISCAT. Use patient factors, oxygenation, recent infection, anemia, surgical site, duration, and urgency to frame risk before surgery.
Assess postoperative pulmonary riskHow to use this page
- 1.Start with risk — ARISCAT frames baseline PPC risk.
- 2.Interpret the signal — Low SpO₂, recent infection, COPD, surgical site, and duration each mean different things.
- 3.Change the plan — Optimize what can be changed, plan for what cannot, and connect risk to ventilation, analgesia, and postoperative support.
Tools to use alongside this page
Start with risk
ARISCAT high risk: what actually changes?
A high score is a trigger for planning, not a reason to cancel. Learn which preoperative and intraoperative decisions it should change.
Low preoperative SpO₂: risk signal, not a diagnosis
SpO₂ below 96% adds 8 points to ARISCAT. The cause determines the response — investigation changes the plan.
Recent respiratory infection: when should elective surgery wait?
Symptom resolution is not airway recovery. The highest-weighted single ARISCAT factor — and what to do while waiting.
COPD with CO₂ retention: what changes before surgery?
Chronic hypercapnia, baseline SpO₂, oxygen strategy, opioid sensitivity, and extubation planning — what changes when ventilatory reserve is limited.
What surgery and anesthesia do to the lung
PPCs: how atelectasis becomes pneumonia
Postoperative pulmonary complications rarely occur in isolation. Understand the atelectasis-to-pneumonia cascade and why early prevention matters.
Lung-protective ventilation: from FRC loss to clinical settings
General anesthesia lowers FRC and promotes atelectasis. Understand how that physiology should shape tidal volume, PEEP, and recruitment decisions.
Regional anesthesia as a pulmonary strategy
Avoiding intubation, sparing opioids, and preserving spontaneous breathing — evidence and technique selection by surgical site.
Duration and emergency surgery: risk you cannot change but can plan for
Procedures over 3 hours and emergency cases carry fixed ARISCAT weight. What changes is the perioperative response.
Intraoperative and postoperative actions
Lung-protective ventilation in non-ARDS surgical patients
6–8 mL/kg IBW, PEEP 5–8 cmH₂O, driving pressure below 15 cmH₂O — evidence from IMPROVE, LAS VEGAS, and PROVHILO with practical adjustments.
Regional anesthesia: how better analgesia protects the lung
Regional techniques can support breathing when they reduce opioid burden, improve cough, and enable deep breathing — but they are not automatically safer.
Postoperative hypoxemia: first interpretation
Early warning signs, the atelectasis–hypoxia cascade, and how to avoid delayed escalation in the first 24 hours after surgery.
Escalating postoperative respiratory support: oxygen, HFNO, NIV, and ICU thresholds
How postoperative hypoxemia is interpreted, when oxygen is enough, and when support should escalate before respiratory reserve is exhausted.
Cases
SpO₂ 92% before colectomy: acceptable or high risk?
A case on how to interpret low preoperative SpO₂ in the context of age, baseline disease, and surgical type — and what should change.
Recent bronchitis before elective surgery: proceed or postpone?
A decision framework for respiratory infection before elective cases — how long to wait and what to do while waiting.
COPD with PaCO₂ 50: chronic hypercapnia or acute failure?
ABG shows PaCO₂ 50 with elevated HCO₃⁻ before abdominal surgery — how baseline CO₂ retention changes oxygen, extubation, and postoperative support.
High ARISCAT score before thoracic surgery: what should actually change?
How a high composite risk score should be translated into specific changes in ventilation, analgesia, and postoperative monitoring.
Postoperative desaturation in PACU: atelectasis, pneumonia, opioid, or fluid?
Early recognition of deteriorating respiratory function and a stepwise escalation framework — from supplemental oxygen to re-intubation.
Foundational overview
Level 1 — Overview
Medical students and junior residents
What is perioperative pulmonary assessment?
The reason for perioperative pulmonary assessment is simple. Some patients develop serious breathing problems after surgery — and most of them show warning signs beforehand.
Postoperative pulmonary complications (PPCs) — pneumonia, atelectasis, respiratory failure, pleural effusion — are among the most common and consequential adverse events after surgery. They can prolong hospital stay, lead to unexpected ICU admission, and worsen outcomes.
This page maps out what to look for and what can be changed. Think of it as the foundation for understanding ARISCAT and other perioperative pulmonary tools.
What are postoperative pulmonary complications (PPCs)?
PPCs cover a range of respiratory problems that develop after surgery. They rarely occur in isolation — each one can trigger or worsen the others.
- Atelectasis — starts early, often within hours, and is the most common trigger of postoperative pneumonia
- Pneumonia — the most outcome-critical PPC, directly linked to increased mortality
- Acute respiratory failure — requires supplemental oxygen, NIV, or re-intubation
- Pleural effusion and bronchospasm — additional contributors in high-risk patients
More common than expected
In the ARISCAT derivation cohort, PPC incidence reached 42% in high-risk patients. This is not a rare complication. Without deliberate assessment and planning, the numbers do not change.
The four pillars of perioperative pulmonary assessment
Perioperative pulmonary assessment becomes clearer when organised into four perspectives.
| Pillar | What to assess | Why it matters |
|---|---|---|
| Patient factors | Age, SpO2, recent infection, anaemia, COPD | Patient-specific risk — some are modifiable before surgery |
| Oxygenation / ventilation | Preoperative SpO2, respiratory reserve | Reflects how much margin the lung has before surgery |
| Surgical insult | Site, duration, urgency | Closer to the diaphragm and longer duration means greater respiratory impact |
| Postoperative care | Analgesia, mobilisation, airway clearance | Targeted management reduces PPC incidence |
Patient risk factors to assess before surgery
The following five patient factors are the most important. The more that are present, the higher the risk.
- Older age (51 years or over) — respiratory muscle strength, cough reflex, and pulmonary reserve all decline with age
- Low preoperative SpO2 (below 96%) — a marker of insufficient respiratory reserve before any surgical stress
- Recent respiratory infection (within 1 month) — airway hyperresponsiveness and secretion burden persist for weeks
- Preoperative anaemia (Hb ≤ 10 g/dL) — reduced oxygen-carrying capacity increases postoperative respiratory workload
- COPD, asthma, or smoking history — pre-existing reduction in pulmonary reserve
Consider delaying elective surgery if there is active infection
A respiratory infection within the past month adds +17 points on ARISCAT — one of the highest-weighted individual factors. For elective procedures, waiting for full recovery (typically 2–4 weeks) is worth considering. Airway reactivity and secretion burden can persist well beyond symptom resolution.