# Situation: A 62-year-old man is brought to the emergency room (ER) because of a severe headache, blurred vision, and new confusion since this morning. He stopped taking his amlodipine and losartan 2 weeks ago. His blood pressure is 220/130 mmHg on repeated readings, and a head computed tomography (CT) scan shows no bleeding. His daughter asks why the team does not bring his blood pressure down to normal right away. Which explanation should the nurse give?

> source: MyMerci (mymerci.kr)  
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> language: ko  
> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 62-year-old man is brought to the emergency room (ER) because of a severe headache, blurred vision, and new confusion since this morning. He stopped taking his amlodipine and losartan 2 weeks ago. His blood pressure is 220/130 mmHg on repeated readings, and a head computed tomography (CT) scan shows no bleeding.

His daughter asks why the team does not bring his blood pressure down to normal right away. Which explanation should the nurse give?

## 보기

1. Nicardipine needs several hours to build up before it lowers pressure
2. A fast drop causes rebound high pressure once the infusion is stopped
3. A fast drop can cut blood flow to a brain used to high pressure **✔ 정답**
4. A fast drop makes the kidneys hold sodium and push the pressure up

**정답: 3**

## 해설

In long-standing severe hypertension, blood flow regulation in the brain and heart adapts to high pressure. Lowering the pressure too fast can reduce blood flow below what these organs need and cause stroke or myocardial ischemia, so the pressure is lowered by no more than about 25% in the first hour and then gradually over the next 24 to 48 hours.

## 심화 해설

Why rapid normalization is dangerous

In a patient with long-standing hypertension, the cerebral circulation does not behave like that of a normotensive person. Under normal conditions, cerebral autoregulation keeps cerebral blood flow stable across a mean arterial pressure range of roughly 50–150 mmHg [1]. In chronic hypertension, however, the autoregulatory curve shifts to the right, meaning the brain has adapted to higher perfusion pressures and now requires a higher blood pressure to maintain adequate flow [1][3].

Lowering blood pressure too quickly can drop cerebral perfusion below the lower limit of this shifted autoregulatory range, producing cerebral ischemia even when the blood pressure reading still looks elevated. That is why the team is not trying to bring the pressure down to normal immediately. The immediate goal is a controlled reduction, generally no more than about 25% below baseline mean arterial pressure in the first hour, followed by gradual lowering over the next 24 to 48 hours [2].

Watch out! A blood pressure of 220/130 mmHg with headache, blurred vision, and confusion raises concern for hypertensive emergency, but the head CT showed no bleeding. Even without intracranial hemorrhage, the brain remains vulnerable to hypoperfusion if the pressure is dropped aggressively.

Key point! The danger is not rebound hypertension after stopping the infusion, and it is not primarily sodium retention by the kidneys. The central concern is cerebral hypoperfusion caused by loss of the brain’s adapted high-pressure perfusion state [1][3].

| Explanation | Why it is incorrect |
| --- | --- |
| Nicardipine needs several hours to build up | Nicardipine is a rapid-acting intravenous calcium channel blocker; its onset is not the reason for slow pressure reduction. |
| Fast drop causes rebound high pressure after infusion stops | Rebound hypertension is not the primary safety concern during acute lowering in hypertensive crisis. |
| Fast drop makes kidneys hold sodium and push pressure up | Sodium retention is a chronic compensatory mechanism, not the immediate danger of rapid reduction. |

The same principle applies to the heart and other vital organs. In chronic hypertension, the left ventricle and vascular beds have remodeled to function at high pressure. An abrupt reduction in systemic pressure can reduce coronary perfusion and precipitate myocardial ischemia, just as it can reduce cerebral perfusion and precipitate stroke [3]. Therefore, the nurse should explain that the team is lowering the pressure gradually to protect organs that have become accustomed to high pressure, especially the brain.References (research sources)

- [1][Unfavorable outcome of aggressive lowering of high blood pressure. Case report].Case reportKuperczkó D, Csécsei P, Komáromy H, Szapáry L, Fehér G (2014) · DOI: 10.1556/OH.2014.30011

- [2]Acute blood pressure reduction exceeding safety and autoregulatory limits following rapid-acting antihypertensives for hypertensive urgency.Research articlePreston RA, Caizapanta EV, Afshartous D, Chaparro L, Bueno PAM, Jimenez G, Rubin P, Bernstein JN. (2026) · DOI: 10.1097/hjh.0000000000004304

- [3]Therapies to Reduce Blood Pressure Acutely.Research articleMiller JB, Kinni H, Amer A, Levy PD (2016) · DOI: 10.1007/s11906-016-0651-8

## 임상 시나리오

Hypertensive Emergency: Why Not Normalize BP Quickly?Protecting cerebral perfusion in chronic hypertension
In chronic hypertension, the cerebral autoregulatory curve shifts rightward, meaning the brain requires higher perfusion pressures to maintain adequate blood flow.

Rapid BP reduction can drop cerebral perfusion below the lower autoregulatory limit, causing cerebral ischemia and stroke even when BP readings still appear elevated.

Goal: reduce BP by no more than 25% in the first hour, then gradually over 24-48 hours.

CautionA BP of 220/130 mmHg with headache, blurred vision, and confusion suggests hypertensive emergency. Even with a normal head CT, aggressive BP lowering risks hypoperfusion injury.

## 핵심 개념

- **Hypertensive emergency** — Severe hypertension with acute target-organ damage, treated in intensive care with titrated intravenous drugs.
- **Cerebral autoregulation** — The brain's ability to keep blood flow steady across a range of pressures; it shifts upward in chronic hypertension.
- **Nicardipine** — An intravenous calcium channel blocker given as a titrated infusion that lowers blood pressure within minutes.
- **Controlled blood pressure reduction** — Lowering pressure by no more than about 25% in the first hour, then gradually over 24 to 48 hours.

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