Postoperative Pulmonary Complications and the ARISCAT Score
ARISCAT quantifies PPC risk from seven preoperative factors. High-risk patients face a 42% complication rate — here is how each factor is scored and how the result changes perioperative management.
How do I use ARISCAT to plan perioperative care?
ARISCAT converts seven preoperative variables into a validated PPC risk score. High-risk patients (≥ 45 points) face a 42% complication rate — the score guides monitoring intensity and prevention strategy.
Key points
ARISCAT converts seven preoperative variables into a validated PPC risk score. Low-risk patients (< 26 points) have a 1.6% PPC rate; high-risk patients (≥ 45 points) face 42.1%. The score identifies modifiable factors — respiratory infection, anaemia, SpO₂ — that can be addressed before elective surgery. The highest single-factor weights are intrathoracic surgery (+24), SpO₂ < 91% (+24), and recent respiratory infection (+17).
Common questions
- What is a PPC? — Any postoperative respiratory complication: atelectasis, pneumonia, respiratory failure, unexpected re-intubation, or bronchospasm. They share a common cascade and often occur together
- What does the ARISCAT score tell me? — It gives an estimated probability of developing a PPC based on seven preoperative factors. It is most useful for identifying high-risk patients who need a modified perioperative plan
- Can a high ARISCAT score be reduced? — Some factors are fixed (age, incision type, surgery duration, emergency status). Others are modifiable: SpO₂ can be investigated, infections can be treated, anaemia can be corrected
The seven ARISCAT factors and their scores
Each factor carries a weight derived from the original Canet et al. (2010) derivation cohort of 2,464 surgical patients across Spain. The weights reflect the independent contribution of each factor after adjusting for the others.
| Factor | Category | Points |
|---|---|---|
| Age | ≤ 50 years | 0 |
| 51–80 years | +3 | |
| > 80 years | +16 | |
| Preoperative SpO₂ (room air) | ≥ 96% | 0 |
| 91–95% | +8 | |
| < 91% | +24 | |
| Respiratory infection in past month | No | 0 |
| Yes | +17 | |
| Preoperative anaemia (Hb ≤ 10 g/dL) | No | 0 |
| Yes | +11 | |
| Surgical incision | Peripheral | 0 |
| Upper abdominal | +15 | |
| Intrathoracic | +24 | |
| Surgery duration | < 2 hours | 0 |
| 2–3 hours | +2 | |
| > 3 hours | +16 | |
| Emergency procedure | No | 0 |
| Yes | +8 |
The three highest-weight factors
Intrathoracic surgery (+24), SpO₂ < 91% (+24), and recent respiratory infection (+17) carry the most weight. A patient with SpO₂ 90% scheduled for an elective upper abdominal operation lasting three hours already accumulates: 24 (SpO₂) + 15 (incision) + 16 (duration) = 55 points — high risk — before age, anaemia, or emergency status are considered.
Risk categories and PPC rates
| Risk category | Score | PPC incidence | Management focus |
|---|---|---|---|
| Low | < 26 points | 1.6% | Standard perioperative care. Lung-protective ventilation. Early mobilisation |
| Intermediate | 26–44 points | 13.3% | Respiratory physiotherapy. Regional anaesthesia consideration. Enhanced postoperative monitoring |
| High | ≥ 45 points | 42.1% | Address modifiable factors before surgery. Plan ICU/HDU. Prioritise regional anaesthesia. Aggressive secretion management |
Management by risk category and phase
| Phase | Low risk | Intermediate risk | High risk |
|---|---|---|---|
| Preoperative | Standard assessment | Respiratory physiotherapy, incentive spirometry, anaemia correction | Delay if active infection, respiratory physiotherapy (urgent), incentive spirometry, anaemia correction |
| Intraoperative | Lung-protective ventilation | Regional anaesthesia where possible, lung-protective ventilation | Regional anaesthesia where possible, lung-protective ventilation |
| Postoperative | Early mobilisation | Enhanced monitoring, early mobilisation | ICU/HDU (urgent), enhanced monitoring (urgent), pain management, secretion clearance, early mobilisation |
Modifiable factors — where preoperative intervention matters
- SpO₂ < 96% — identify and treat the cause. COPD with suboptimal inhaler therapy, heart failure, and respiratory infection are common reversible contributors. Re-score after optimisation
- Recent respiratory infection — this is the highest-weight binary factor (+17). For elective surgery, waiting until the airway has recovered (typically 4 weeks after lower respiratory tract infection) can move a patient from high to intermediate risk
- Preoperative anaemia — Hb ≤ 10 g/dL adds 11 points. Iron deficiency anaemia can often be corrected with oral or intravenous iron before elective surgery. Haemoglobin above 10 g/dL improves oxygen-carrying capacity and tissue oxygenation
- Upper abdominal surgery timing — where clinical circumstances allow, laparoscopic rather than open approach reduces incision-related risk, though this is a surgical rather than anaesthetic decision
Common pitfalls
- 'The score is intermediate — that's not too bad.' — 13.3% means roughly 1 in 7 patients in this category develops a PPC. These patients benefit meaningfully from respiratory physiotherapy and enhanced monitoring
- 'The patient looks fine, the score must be wrong.' — ARISCAT is intentionally independent of subjective clinical impression. The quantified factors (SpO₂, Hb, infection history) predict risk that symptoms may not yet reflect
- 'Nothing can be done for high-risk patients.' — Several factors are modifiable. Even reducing SpO₂ from 90% to 96% or clearing an infection before surgery can shift the score significantly
- 'ARISCAT only applies to the postoperative ward.' — The score informs decisions from before induction (regional anaesthesia planning, ICU booking) through to discharge planning. It is most useful when applied at the preoperative assessment visit
- ARISCAT Pulmonary Risk Score
Calculate the score from the seven factors — low, intermediate, or high risk with PPC incidence and management recommendations
- Postoperative pulmonary complications — classification and cascade
What each PPC type is, how atelectasis leads to pneumonia, and where to intervene
- Is SpO₂ 92% dangerous? Preoperative oxygenation for anaesthetists
How the SpO₂ factor in ARISCAT connects to preoperative oxygenation assessment
- Is preoperative spirometry useful? Evidence and practiceComing soon
The role of pulmonary function testing alongside ARISCAT in preoperative risk stratification
- Causes of low preoperative SpO₂: COPD, atelectasis, or measurement error?Coming soon
What to do when the ARISCAT SpO₂ criterion is triggered
- Case: SpO₂ 92% before surgery — what to do next?
See how the SpO₂ ARISCAT factor plays out in a real preoperative case
Written by
Kozo Watanabe, MD
Chief of Anesthesiology
Practicing anesthesiologist specializing in cardiovascular anesthesia and perioperative management. Clinical focus includes perioperative risk assessment, respiratory and hemodynamic management, and decision support for high-risk surgical patients.
- Cardiovascular anesthesia and cardiac surgery
- Perioperative critical care
- Perioperative respiratory management (oxygenation, ventilation, ABG interpretation)