Situation: A 55-year-old woman weighing 70 kg is recovering from an open abdominal operation done under general anesthesia. She has no drug allergies and no history of sleep apnea. In the post-anesthesia care unit (PACU), the nurse uses the modified Aldrete score to decide when she may be transferred. Which parameter is one of the five that this score rates?

The modified Aldrete score rates activity, breathing, circulation, consciousness, and oxygen saturation, each 0–2, and transfer usually requires 9 or more of 10. Pain, urine output, and temperature are assessed in the PACU but are not part of this score.

The modified Aldrete score is a structured, five-domain tool used in the post-anesthesia care unit (PACU) to determine when a patient is stable enough to leave the recovery area. The five parameters it rates are activity, breathing, circulation, consciousness, and oxygen saturation. Each domain receives a score from 0 to 2, for a maximum total of 10. A score of 9 or higher is generally accepted as indicating readiness for transfer from the PACU to a regular surgical unit ^[1][2].

The correct answer is oxygen saturation. In the original Aldrete score, the respiratory component was assessed by observing the patient's ability to breathe deeply and cough. The modified version replaced this with a more objective measure: oxygen saturation as measured by pulse oximetry. This change reflects the understanding that a patient can appear to be breathing adequately while still experiencing clinically significant hypoxemia, particularly in the early period after general anesthesia when residual neuromuscular blockade, atelectasis, and opioid-related respiratory depression are common ^[2].

The scoring for oxygen saturation in the modified Aldrete score is straightforward. A patient receives 2 points if the SpO₂ is greater than 92% on room air. A score of 1 is given when supplemental oxygen is required to maintain an SpO₂ above 90%. A score of 0 indicates an SpO₂ below 90% even with oxygen supplementation. This graded approach ensures that the nurse not only observes the saturation value but also considers the intervention required to achieve it ^[2][3].

The other options are important PACU assessments but are not components of the modified Aldrete score. Pain intensity is monitored using tools such as a numeric rating scale and is managed aggressively in the PACU, but it does not contribute to the Aldrete total. Urine output is tracked to evaluate fluid balance and renal perfusion after surgery, yet it is not one of the five scored domains. Core body temperature is closely watched because hypothermia can delay recovery and increase oxygen consumption, but thermoregulation is likewise not part of the Aldrete scoring system ^[3].

The rationale for using a structured scoring system rather than a fixed time interval is supported by evidence comparing discharge readiness tools. In a prospective study of adults undergoing general anesthesia, the Modified Aldrete Score (MAS) was used alongside the White Fast-Track Score to evaluate PACU discharge readiness against a conventional 60-minute time-based criterion. The study highlights that scoring systems allow for individualized assessment of physiologic recovery rather than relying solely on elapsed time, which may not reflect true readiness in every patient ^[1]. This is particularly relevant for a patient like the one in the scenario, who is recovering from an open abdominal procedure under general anesthesia and may have variable rates of return of airway reflexes, motor function, and hemodynamic stability.

Parameter	Modified Aldrete score domain	Rationale for inclusion or exclusion
Oxygen saturation	Yes (breathing domain)	Objective measure of gas exchange; detects hypoxemia not visible by observation alone [2]
Core body temperature	No	Monitored for hypothermia risk but not part of the five scored domains [3]
Urine output	No	Assessed for renal perfusion and fluid status; separate from Aldrete criteria [3]
Pain intensity	No	Managed as a comfort and safety priority but does not contribute to the Aldrete total [3]

Key point! The modified Aldrete score is a physiologic recovery tool, not a comprehensive PACU assessment. It focuses on the five domains most directly affected by anesthetic agents and surgical stress: activity, breathing, circulation, consciousness, and oxygen saturation. Pain, temperature, urine output, nausea, and surgical site status are all evaluated separately and may delay discharge even when the Aldrete score is 9 or 10 ^[2][3].

Watch out! A common error is to assume that any parameter monitored in the PACU is part of the Aldrete score. The score is deliberately limited to five domains to keep it quick and reproducible at the bedside. When a question asks which parameter is included, oxygen saturation is the only option among the choices that belongs to the five scored domains. The other options—temperature, urine output, and pain—are assessed but not scored in this tool ^[1][2][3].