ARISCAT High Risk: What Actually Changes?
A high ARISCAT score is a planning trigger, not a diagnosis. What changes depends on separating modifiable factors from those that require planning.
Key points
- ARISCAT stratifies PPC risk into three categories: low (1.6%), intermediate (13.3%), and high (≥ 45 points, 42.1%). The score measures composite risk — it does not identify which specific complication will develop.
- A high score is a planning trigger, not a reason to cancel surgery. It starts a structured team conversation about which modifiable factors can be addressed and what perioperative changes are warranted.
- Modifiable factors — recent respiratory infection, preoperative anaemia, low SpO₂ — should be addressed before elective surgery wherever possible. Each represents a meaningful point reduction in the score.
- Non-modifiable factors — age, surgical site, duration, urgency — cannot be changed. They shift the focus to planning: ventilation strategy, analgesia, monitoring level, and postoperative setting.
- High ARISCAT is not a surgical contraindication. It is information that should be shared between the surgical team, anaesthesia team, and patient before the date of surgery.
You calculate ARISCAT ≥ 45 before elective upper abdominal surgery. What changes?
The score identifies high risk — 42% PPC probability. The next step is separating the factors that can be modified preoperatively from those that require intraoperative and postoperative planning.
When to use this page
Use this page after calculating an ARISCAT score ≥ 45, when planning a case with known respiratory risk factors, or when deciding whether to proceed with or delay elective surgery in a patient with respiratory comorbidities.
What the score tells you — and what it does not
ARISCAT converts seven preoperative variables into a composite risk score validated in a cohort of 2,464 surgical patients. A score ≥ 45 places a patient in the high-risk category, where the observed PPC rate was 42.1%. This is the probability under standard care — not a fixed outcome.
| Risk category | Score | PPC rate | Clinical implication |
|---|---|---|---|
| Low | < 26 | 1.6% | Standard perioperative management |
| Intermediate | 26–44 | 13.3% | Enhanced monitoring, respiratory physiotherapy |
| High | ≥ 45 | 42.1% | Structured team planning required — see below |
The score does not diagnose the mechanism
Two patients can reach the same score through entirely different factor combinations. A 70-year-old with low SpO₂ and a long intrathoracic case may score identically to a 55-year-old with recent pneumonia and planned upper abdominal surgery. The score does not explain why the risk is high — that requires reading the individual factors.
Why 42% is a baseline, not a fixed outcome
The ARISCAT derivation cohort reflected routine perioperative management. A 42.1% PPC rate in high-risk patients describes what happens without targeted intervention — not what must happen. The score's purpose is identification: to flag which patients benefit most from a modified perioperative plan.
Modifiable factors are the intervention point
For every modifiable factor corrected before elective surgery, the composite risk decreases. A patient cleared of respiratory infection, with corrected anaemia and stabilised SpO₂, may move from high to intermediate risk. The score should be recalculated after optimisation to confirm the shift.
Separating what can be changed from what must be planned for
| Factor | Modifiability | Preoperative action |
|---|---|---|
| Respiratory infection (within 1 month) | Modifiable — wait for airway recovery | Delay elective surgery until resolved; typically 2–4 weeks after symptom resolution for lower respiratory tract infection |
| Anaemia (Hb ≤ 10 g/dL) | Modifiable — correct if time allows | Oral or IV iron therapy; target Hb > 10 g/dL before elective surgery |
| Low SpO₂ (< 96%) | Modifiable if cause is treatable | Identify and treat the cause (COPD inhaler optimisation, heart failure, infection). Refer to respiratory or cardiology for unexplained cases. Re-score after optimisation |
| Age (≥ 51 years) | Not modifiable | Account for reduced respiratory reserve. Plan postoperative monitoring accordingly |
| Surgical site (upper abdominal / intrathoracic) | Not modifiable | Discuss analgesic strategy with surgical team. Thoracic epidural for upper abdominal and thoracic surgery |
| Surgery duration (> 3 hours) | Not modifiable | Plan for extended intraoperative lung protection. Enhanced postoperative monitoring |
| Emergency surgery | Not modifiable | Shift from preoperative optimisation to risk-informed intraoperative and postoperative management |
What a high ARISCAT score should change
| Phase | Key changes |
|---|---|
| Preoperative | Delay elective surgery if active respiratory infection is present. Correct Hb if ≤ 10 g/dL. Investigate unexplained SpO₂ < 96%. Teach incentive spirometry preoperatively. Confirm ICU or HDU availability with the surgical team. |
| Intraoperative | Lung-protective ventilation should be standard for high-risk patients, but settings must be individualized to compliance, position, hemodynamics, and obstructive physiology: target TV 6–8 mL/kg IBW, individualized PEEP, and monitor driving pressure — targeting ΔP < 15 cmH₂O where clinically feasible. Regional anaesthesia where feasible: thoracic epidural for upper abdominal, paravertebral or spinal as appropriate. Minimise intraoperative opioid use. |
| Postoperative | Enhanced SpO₂ monitoring — HDU if score ≥ 45 and upper abdominal or thoracic surgery. Optimise analgesia quality: inadequate pain control is the leading driver of postoperative atelectasis. Early mobilisation from day 1. HFNO or NIV availability for patients at risk of respiratory failure. |
A high score is a team conversation, not a solo decision
A high ARISCAT score should be documented in the anaesthetic record, communicated to the ward team, and discussed with the patient before surgery. The perioperative plan — analgesic technique, postoperative monitoring level, ICU or HDU booking — is most effective when agreed before the day of the case.
- Low preoperative SpO₂: risk signal, not a diagnosis
What SpO₂ below 96% means perioperatively and when it changes management
- Respiratory infection and the decision to delay surgery
When to delay, how long to wait, and what to do during the waiting period
- Perioperative lung-protective ventilation
TV, PEEP, and driving pressure targets with evidence from IMPROVE and LAS VEGAS
- Postoperative respiratory failure: when and how to escalate
Early warning signs and stepwise escalation from oxygen to re-intubation
Clinical content by Kozo Watanabe, MD View profile →
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