Before We Start
Why nurses use COAT alongside MORPHINE
MORPHINE gives you the full side effect picture of opioids. COAT is the fast bedside version — the four things that happen to almost every patient on opioids that you need to monitor and manage every shift.
Think of it this way: MORPHINE is what you study to understand the drug. COAT is what you run through in your head when you walk into a patient's room on opioids. It takes 60 seconds to check all four, and it catches the complications that hurt people.
💡 Which Opioids Does COAT Apply To?
All of them. Morphine, oxycodone, hydromorphone (Dilaudid), fentanyl, codeine, tramadol, meperidine — the COAT side effects occur across the entire opioid class. The intensity differs (fentanyl causes less histamine release than morphine; meperidine has unique neurotoxicity) but the core four — Constipation, Over-sedation, Aspiration risk, respiratory depression — are universal opioid risks.
The Mnemonic
COAT — the four bedside opioid concerns
C — Constipation
The only opioid side effect that does NOT get better over time
Opioids bind to receptors in the gut wall and slow peristalsis — the rhythmic contractions that move stool through the intestines. The result is constipation that starts with the first dose and persists for as long as the patient is on opioids.
Why this is different from all other opioid side effects: Sedation, nausea, and even some respiratory effects improve as the body develops tolerance. Constipation never develops tolerance. A patient on long-term opioids will be constipated for the entire duration — without intervention.
The standard of care: Every patient starting opioids should receive a bowel regimen from day one — not after they haven't had a bowel movement for five days. The standard is a stimulant laxative (senna) with or without a stool softener (docusate).
Complications of untreated constipation: Fecal impaction, bowel obstruction, paralytic ileus, severe abdominal pain that gets confused with the original pain being treated.
💊 The nursing standard: "Start laxatives when you start opioids." On NCLEX, if a question asks what to include in the care plan for a patient starting around-the-clock opioids, a bowel regimen is always a correct answer.
O — Over-sedation
The warning sign before respiratory depression
Over-sedation means the opioid has depressed the CNS more than intended — the patient is drowsier than expected, harder to arouse, or losing responsiveness.
Why it matters so much: Over-sedation is the warning sign that respiratory depression is coming. The brain gets depressed before the respiratory drive fails. This gives the nurse a window to act — if they catch it.
The Pasero Opioid-Induced Sedation Scale (POSS):
• S = Sleeping, easy to arouse → give dose, monitor
• 1 = Awake and alert → give dose
• 2 = Occasionally drowsy, easy to arouse → give dose, monitor closely
• 3 = Frequently drowsy, difficult to arouse → hold dose, call provider, increase monitoring
• 4 = Somnolent, barely responsive → hold dose, call provider, consider Narcan
Nursing action at level 3: Do not give next dose. Stimulate the patient. Notify provider. Be ready to give Narcan. Increase monitoring frequency. Document thoroughly.
💊 The most dangerous time for opioid over-sedation is the first 24 hours — especially in opioid-naive patients. Night shift nurses need to be especially vigilant because sedated patients do not call for help.
A — Aspiration risk (Nausea/Vomiting)
Sedation + vomiting = airway emergency
Opioids cause nausea and vomiting by stimulating the chemoreceptor trigger zone in the brainstem. This is common — especially with first doses and in opioid-naive patients. On its own, nausea is uncomfortable. Combined with sedation, it becomes dangerous.
The aspiration chain:
1. Patient receives opioid → becomes sedated
2. Sedated patient vomits
3. Sedated patient cannot protect their airway — gag reflex is blunted
4. Stomach contents enter the lungs → aspiration pneumonia
5. Aspiration pneumonia can be fatal
Prevention nursing actions:
• HOB elevated 30–45° for all sedated patients on opioids
• NPO or clear liquids only for sedation level 3+
• Suction available at bedside for high-risk patients
• Antiemetics proactively for high-risk patients (history of PONV, first opioid dose)
• If patient vomits and is sedated → turn to side immediately, suction if needed
💊 Post-surgical patients are at highest aspiration risk: they have just had opioids for anesthesia, they are sedated from the procedure, and their gag reflexes may be slow to return. Head of bed positioning is not optional — it is a life-safety intervention.
T — respiratory depression (The killer)
The opioid side effect that ends lives — and how to stop it
Respiratory depression is what the entire COAT mnemonic is building toward. It is the reason opioids require the assessment frequency they do, the reason Narcan exists, and the reason nurses are trained to recognize the warning signs.
What happens physiologically: Opioids bind to mu receptors in the brainstem's respiratory center. At therapeutic doses, this reduces pain signaling. At too-high doses or in sensitive patients, it suppresses the drive to breathe — the brainstem stops sending the signal to take the next breath.
The assessment parameters:
• RR below 12 = concerning, assess further and notify provider
• RR below 8 = emergency
• SpO2 below 90% with opioids on board = respiratory depression is happening
• Shallow, irregular breathing is more dangerous than a rate alone
The antidote: Naloxone (Narcan) 0.4–2mg IV/IM/IN/SC. Reverses opioid binding within 1–2 minutes. Duration of effect: 30–90 minutes. Problem: most opioids last longer than Narcan — patient must be monitored for re-narcotization (the opioid outlasting the antidote).
💊 After giving Narcan, the nurse stays. Narcan wears off in 30–90 minutes. If the opioid is still in the system (fentanyl patches, long-acting opioids), the patient can slip back into respiratory depression. Narcan may need to be redosed, and the provider needs to know immediately.
🏥 Clinical Scenario — Running COAT on a Post-Op Patient
Mrs. Chen, 71 years old, is day 1 post-op from hip replacement. She has a morphine PCA (patient-controlled analgesia) — she can press the button to give herself a dose within safe limits. You are doing your 8am assessment.
C
Constipation check: "When was your last bowel movement?" — "Before surgery, 2 days ago." She has not had one since. Bowel sounds present but hypoactive. Abdomen soft, no distension yet. → Start bowel regimen now. Do not wait for her to complain. Senna ordered — give it. Document last BM and bowel sounds. Follow up.
O
Over-sedation check: She opens her eyes when you call her name but drifts back to sleep quickly. POSS score 2 (occasionally drowsy, easy to arouse). PCA log shows she pressed the button 18 times in the past 8 hours. → Sedation score 2 is within acceptable range but monitor closely. Reinforce: if she is too sleepy, pain management is not working safely — the dose may need adjustment, not more button presses.
A
Aspiration risk check: HOB currently at 15°. She reports nausea since midnight — rated 5/10. No vomiting yet. → Raise HOB to 30° immediately. Administer ondansetron as ordered. Instruct patient to call before repositioning. Suction available at bedside. Notify provider of ongoing nausea — antiemetic regimen may need adjustment.
T
Respiratory depression check: RR 14, SpO2 96%, breath sounds clear bilaterally, no use of accessory muscles. → Respirations adequate. Continue to monitor. Narcan available in the room per protocol. Reassess in 1 hour given sedation level of 2 and active nausea.
📌 NCLEX Application
COAT questions on NCLEX appear as priority questions — what does the nurse address first?
The priority order for COAT mirrors Maslow: airway first, then breathing, then circulation, then everything else.
• If the question mentions respiratory depression (RR 8, SpO2 88%) → that is always priority one
• If the question mentions over-sedation + nausea → aspiration risk is the concern — position and suction
• If all four are present → address T (respiratory depression) first, then O (over-sedation), then A (aspiration risk), then C (constipation)
Unique NCLEX trap: A question mentions a patient on opioids who "hasn't had a bowel movement in 4 days." Constipation is serious here, but if respiratory rate is also mentioned as 9 → breathing is still priority. Constipation is treated after the airway is safe.
⚠️ The Trap — Waiting for Constipation to Happen
This is one of the most common nursing comfort care errors: waiting until the patient reports constipation before starting a bowel regimen.
Why this is wrong: Opioids cause constipation with the first dose. By the time a patient says "I haven't gone in 5 days," they may have a fecal impaction — a packed mass of stool that can cause a bowel obstruction and requires manual disimpaction or enemas to resolve. This is painful, demoralizing, and preventable.
The correct approach: When you transcribe the opioid order, look for a bowel regimen order alongside it. If there isn't one, call the provider and ask. Senna is the first-line agent because it stimulates peristalsis — it gets the bowels moving. Docusate (Colace) alone is not enough — it softens stool but doesn't stimulate movement.
NCLEX angle: "Which order would the nurse anticipate when a patient is started on long-term opioid therapy?" → Senna (or senna-docusate). Not just docusate alone.
✓ Quick Self-Test
Answer before checking:
1. Which COAT side effect does NOT improve with continued opioid use?
2. A patient on morphine PCA has a sedation score of 3. What is your first action?
3. Why is nausea particularly dangerous in a sedated opioid patient?
4. What is the respiratory rate threshold for holding an opioid dose?
5. A patient on oxycodone gets Narcan. Why must you continue monitoring after the Narcan works?
Answers:
1. C — Constipation. All other opioid effects develop some tolerance; constipation persists for the entire duration of opioid therapy.
2. Hold the dose, stimulate the patient, notify the provider, increase monitoring frequency, and have Narcan ready. Score 3 means the drug is too much — do not give more.
3. A sedated patient cannot protect their airway. If they vomit while sedated, they may aspirate — stomach contents enter the lungs, causing aspiration pneumonia.
4. Hold if respiratory rate is below 12 breaths per minute. RR below 8 is an emergency.
5. Narcan lasts 30–90 minutes. Oxycodone lasts 4–6 hours. The opioid will outlast the Narcan — the patient can slide back into respiratory depression (re-narcotization) after the Narcan wears off. Stay at bedside and be ready to redose.