6 Perioperative Monitoring and Safety

The perioperative monitoring cycle

Perioperative care spans three connected phases: preoperative preparation, intraoperative care, and postoperative recovery. Monitoring combines measurements, such as vital signs and oxygen saturation, with repeated clinical assessment.

A reading is most useful when interpreted alongside the patient’s baseline, the procedure, the pattern of change, and the response to treatment. A single measurement should not replace assessment of the whole clinical picture.

Before surgery: assess and prepare

A Baseline assessment helps the team understand the patient’s condition before surgery and recognize meaningful changes later. Review the patient’s history, current condition, allergies, prior anesthetic problems, medications and supplements, relevant comorbidities, and planned procedure and anesthetic.

Assess relevant findings such as vital signs, oxygenation, mental status, mobility, pain, hydration, skin, and neurologic or cardiopulmonary status. Confirm identity, procedure and site, consent, and required preparation with the patient and team.

Testing should be selected according to the patient’s health, symptoms, medications, and planned procedure rather than ordered automatically. When indicated, it may include blood counts, electrolytes or renal function, coagulation studies, ECG, pregnancy testing, or blood type and screen. Review abnormal or changing results in context and communicate concerns before the procedure. Clarify medication and fasting instructions with the perioperative team rather than changing them independently.

The WHO Surgical Safety Checklist supports team communication through pauses before anesthesia, before incision, and before the patient leaves the operating room. Checklists help prevent omissions but do not replace clinical judgment.

During surgery: monitor and respond

During surgery, an anesthesia professional continually evaluates the patient and adapts monitoring to the anesthetic, operation, and individual risk.

Core monitoring considers:

• Oxygenation: Pulse oximetry measures oxygen saturation; inspired oxygen concentration is monitored when applicable.

• Ventilation: Observe and appropriately measure breathing. Exhaled carbon dioxide monitoring is used when indicated, including to confirm and track ventilation with an airway device.

• Circulation: Assess heart rate, blood pressure, and ECG as appropriate, along with perfusion and responses to blood loss, fluids, and anesthetic drugs.

• Temperature: Monitor when clinically indicated and prevent or treat unintended temperature changes.

Additional monitoring may be appropriate for major or high-risk surgery, significant blood loss, or specific diseases. Depending on the situation, this can include invasive blood pressure, cardiac output, blood gases, neuromuscular function, or urine output; these measures are not required for every patient.

Track fluid administration and losses, estimated blood loss, relevant laboratory results, medications, positioning, and the surgical field. A sudden change—such as falling blood pressure, increasing heart rate, reduced oxygen saturation, rising airway pressures, or unexpected bleeding—calls for prompt assessment and communication. Speak up about unresolved safety concerns.

After surgery: reassess and hand off

During emergence and recovery, reassess airway patency, respiratory rate and effort, oxygen saturation, pulse, blood pressure, mental status, temperature, pain, nausea or vomiting, hydration, and wound or drain bleeding. Assess neuromuscular recovery when relevant. Check urine output or ability to void when indicated by the patient, procedure, or care plan.

A useful Handoff communicates the procedure and anesthetic, baseline and current status, important events, medications, fluids and blood loss, airway or device status, drains, pending tests, identified risks, and the monitoring or treatment plan. Continue observation at a level suited to the patient’s risk. Transfer or discharge requires appropriate clinical criteria and handoff.

Recognize complications and escalate

Early recognition depends on connecting symptoms with trends and escalating concerns promptly.

• Airway obstruction or hypoventilation: Noisy or difficult breathing, apnea, increasing sedation, reduced oxygen saturation, or abnormal ventilation can be warning signs. Opioids and residual anesthetic or neuromuscular-blocking effects may contribute. Prioritize airway and breathing assessment and escalate promptly.

• Hemorrhage or circulatory instability: Increasing wound or drain blood, pallor, cool or clammy skin, dizziness, altered mental status, falling blood pressure, or rising heart rate may indicate a problem. Consider concealed bleeding as well as visible loss, and report concerning trends urgently.

• Nausea, vomiting, and aspiration risk: Assess symptoms, protect the airway when needed, and follow the prescribed treatment plan.

• Temperature changes: Assess temperature and warming measures. Unexpected fever or other signs of infection need clinical review.

• Urinary retention or fluid imbalance: Monitor intake and output when indicated. Consider retention if the patient cannot void or develops discomfort.

• Possible surgical-site infection: Redness, increasing pain, drainage, or fever after surgery warrants contacting a health professional.

• Other serious events: New confusion, chest pain, seizure, severe allergic reaction, or sudden respiratory or circulatory decline requires immediate escalation through the facility’s emergency response process.

Takeaway: Establish a baseline, anticipate risks, observe and trend findings, communicate changes, and reassess after interventions. Checklists and clear handoffs support safe care, while timely escalation remains essential.