# A nurse is caring for a patient receiving morphine sulfate 4 mg IV every 4 hours for postoperative pain. Which assessment finding would require the nurse to withhold the medication and notify the physician immediately?

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> language: ko  
> subject: Pharmacology

## 문제

A nurse is caring for a patient receiving morphine sulfate 4 mg IV every 4 hours for postoperative pain. Which assessment finding would require the nurse to withhold the medication and notify the physician immediately?

## 보기

1. Blood pressure 90/60 mmHg, heart rate 110 bpm, and dizziness on standing
2. Respiratory rate 10 breaths per minute, shallow breathing, and oxygen saturation 88% **✔ 정답**
3. Pain level 8/10, grimacing, and requesting additional pain medication
4. Drowsiness, arousable to verbal stimuli, and pupils constricted to 2 mm

**정답: 2**

## 해설

Respiratory rate of 10 breaths/min with shallow breathing and oxygen saturation of 88% indicates severe opioid-induced respiratory depression, requiring medication withholding and physician notification. Other findings are less urgent.

## 심화 해설

Clinical Reasoning and Priority Setting

This question tests your ability to recognize a life-threatening adverse effect of opioid analgesics and prioritize nursing actions. Morphine, a pure mu-opioid receptor agonist, provides effective postoperative pain relief but carries a significant risk of dose-dependent respiratory depression. Understanding the mechanism and the hierarchy of clinical urgency is essential for safe medication administration.

Analysis of the Correct Answer (Option 2)

The assessment findings in Option 2 represent the classic triad of severe opioid-induced respiratory depression. The nurse must withhold the morphine and immediately contact the physician because this patient is at imminent risk of respiratory arrest.

The underlying mechanism involves morphine's action on mu-opioid receptors in the brainstem respiratory centers, specifically the pre-Bötzinger complex. Stimulation of these receptors blunts the chemoreceptor response to rising arterial carbon dioxide (CO₂), leading to a progressive decrease in respiratory rate and depth. A respiratory rate of 10 breaths per minute with shallow breathing indicates a failing ventilatory drive. The oxygen saturation of 88% is a late and critical sign, reflecting severe hypoxemia resulting from hypoventilation. This sequence of events is a direct manifestation of the dose-dependent adverse effects described in the literature, where neuraxial and systemic opioids can cause delayed respiratory depression due to their action on central nervous system receptors [1]. The immediate priority is to stimulate the patient, administer supplemental oxygen, prepare to administer an opioid antagonist like naloxone, and notify the provider.

Analysis of Incorrect Options

- Option 1: Blood pressure of 90/60 mmHg, heart rate of 110 bpm, and dizziness on standing describe a clinical picture of orthostatic hypotension and compensatory sinus tachycardia. While this requires further assessment, it is a common and less immediately life-threatening effect of morphine, primarily due to histamine release and decreased sympathetic tone. The patient is conscious and maintaining their airway, making this a lower priority than respiratory failure.

- Option 3: A pain level of 8/10 with grimacing indicates inadequate analgesia. The patient’s request for more medication is an expected finding in the postoperative period. The nurse’s role here is to reassess the pain, consider non-pharmacological interventions, and collaborate with the physician to optimize the pain management plan. Withholding the medication would be contraindicated and unethical, as the patient is in distress but not exhibiting signs of toxicity.

- Option 4: Drowsiness where the patient is arousable to verbal stimuli and pupils constricted to 2 mm are expected pharmacological effects of morphine. Miosis is a classic mu-receptor effect, and mild sedation is common, especially in the early postoperative phase. The key safety distinction is that the patient is easily arousable, indicating a protected airway and adequate ventilation. This represents a therapeutic, not toxic, response and requires continued monitoring, not an emergency intervention.

Clinical Application and Safe Practice

When administering opioids, your nursing assessment must follow a specific hierarchy: level of consciousness, respiratory status, and then hemodynamic status. A decrease in respiratory rate and depth is the most sensitive and critical indicator of impending respiratory failure. The concept of "feedback-regulated" dosing is being explored in newer opioid delivery systems to reduce adverse events like postoperative nausea and vomiting by preventing excessive opioid exposure, but the fundamental risk of respiratory depression remains with all mu-agonists [4]. Your clinical judgment must always prioritize airway and breathing. A sedated patient who is easily aroused is safe; a patient with a depressed respiratory rate and hypoxia is not. This principle is universally applied, from managing acute postoperative pain to monitoring neonates for opioid withdrawal syndrome, where respiratory stability is a core component of the nursing assessment model [2].

## 임상 시나리오

Opioid-Induced Respiratory Depression: Immediate ResponseRecognizing and Acting on a Life-Threatening Emergency
A respiratory rate of 10/min with shallow breathing and SpO2 88% indicates severe hypoventilation. This is a late sign of failing ventilatory drive due to blunted CO2 response in the brainstem.

The immediate nursing action is to withhold the opioid, administer oxygen, and notify the physician. Prepare to administer naloxone, an opioid antagonist, as prescribed.

CautionDo not confuse expected effects like drowsiness and pinpoint pupils with toxicity. Always prioritize Airway and Breathing over pain or blood pressure changes when administering opioids.

## 핵심 개념

- **Opioid-Induced Respiratory Depression** — A life-threatening adverse effect where opioids blunt the brainstem's response to CO2, leading to decreased respiratory rate, shallow breathing, and hypoxemia.
- **Pre-Bötzinger Complex** — A region in the brainstem's medulla oblongata that generates the respiratory rhythm and is highly sensitive to mu-opioid receptor agonists.
- **Mu-Opioid Receptor Agonist** — A class of drugs, including morphine, that bind to mu receptors to produce analgesia, euphoria, sedation, and at higher doses, respiratory depression.
- **Nursing Priority Setting (ABC)** — A framework for clinical decision-making that prioritizes Airway, Breathing, and Circulation. Respiratory depression is a 'Breathing' problem and takes precedence over pain or circulation.

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