# Situation: A 24-year-old woman with asthma is brought to the emergency room (ER) with wheezing and breathlessness that began after a viral cold. At home she uses only a salbutamol (albuterol) inhaler, about 6 to 8 times a week. She has no other illness, takes no other medicines, and her oxygen saturation by pulse oximetry (SpO2) is monitored continuously. On arrival, before any treatment, her SpO2 is 89% on room air. The physician orders oxygen by nasal cannula, titrated to the target recommended by the Global Initiative for Asthma guideline for adults. Which SpO2 range should the nurse aim for?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629677  
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> 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 24-year-old woman with asthma is brought to the emergency room (ER) with wheezing and breathlessness that began after a viral cold. At home she uses only a salbutamol (albuterol) inhaler, about 6 to 8 times a week. She has no other illness, takes no other medicines, and her oxygen saturation by pulse oximetry (SpO2) is monitored continuously.

On arrival, before any treatment, her SpO2 is 89% on room air. The physician orders oxygen by nasal cannula, titrated to the target recommended by the Global Initiative for Asthma guideline for adults. Which SpO2 range should the nurse aim for?

## 보기

1. 93% to 95% **✔ 정답**
2. 96% to 100%
3. 88% to 92%
4. 90% to 94%

**정답: 1**

## 해설

The Global Initiative for Asthma guideline gives oxygen to adults when SpO2 is below 92% and titrates it to keep SpO2 at about 93% to 95%, avoiding both hypoxemia and unnecessary high-concentration oxygen. The lower 88% to 92% target is reserved for clients at risk of carbon dioxide retention, such as those with chronic obstructive pulmonary disease (COPD).

## 심화 해설

Oxygen Target in Acute Asthma

The correct target is 93% to 95%. This range reflects the balance between correcting hypoxemia and avoiding the harms of excessive oxygen administration in asthma.

In acute asthma, airflow obstruction causes ventilation-perfusion (V/Q) mismatch. Some alveoli are poorly ventilated but still perfused, producing areas of low oxygen content in arterial blood. The immediate response is to raise the fraction of inspired oxygen (FiO₂). However, asthma is primarily a disease of bronchoconstriction and airway inflammation, not one of chronic carbon dioxide retention. Therefore, the oxygen target can be higher than the conservative range used in COPD.

The Global Initiative for Asthma recommends starting oxygen when SpO₂ falls below 92% and titrating to maintain SpO₂ at 93% to 95% in adults. This prevents tissue hypoxia while avoiding unnecessarily high oxygen concentrations that can mask clinical deterioration, delay recognition of worsening ventilation, and potentially contribute to absorption atelectasis.

The lower target of 88% to 92% is reserved for patients at risk of hypercapnic respiratory failure. In COPD, chronic CO₂ retention blunts the hypoxic drive, and overzealous oxygen can suppress respiratory effort, worsening hypercapnia. Key point! Asthma does not typically carry this risk unless the patient has concurrent COPD or severe, prolonged obstruction with respiratory muscle fatigue.

The Saudi expert consensus on acute asthma and COPD exacerbation management reinforces this distinction. It emphasizes that oxygen therapy in acute asthma should be guided by SpO₂ monitoring, with the goal of maintaining adequate oxygenation without excessive FiO₂. The consensus also highlights that aerosolized bronchodilator delivery—often driven by oxygen—must be coordinated with the overall oxygen strategy, since high-flow oxygen used to power nebulizers can inadvertently raise FiO₂ above the intended target.

| Target Group | SpO₂ Range | Rationale |
| --- | --- | --- |
| Acute asthma (adult) | 93% to 95% | Correct hypoxemia; no chronic CO₂ retention risk in most cases |
| COPD or CO₂ retention risk | 88% to 92% | Prevent suppression of hypoxic drive and worsening hypercapnia |

Watch out! A patient using salbutamol 6 to 8 times per week indicates poorly controlled asthma and a higher risk of severe exacerbation, but it does not change the oxygen target. The SpO₂ of 89% on arrival confirms the need for supplemental oxygen, and the nurse titrates the nasal cannula flow to keep the reading within 93% to 95%, reassessing frequently because bronchospasm can fluctuate rapidly.

## 임상 시나리오

Oxygen Titration in Acute AsthmaGINA-recommended SpO2 target for adults
In acute asthma, start oxygen when SpO2 < 92% and titrate to maintain 93% to 95%. Asthma causes V/Q mismatch from bronchoconstriction, not chronic CO2 retention, so a higher target than COPD is safe and appropriate.

The lower target of 88% to 92% is reserved for patients at risk of hypercapnic respiratory failure, such as those with COPD. Asthma alone does not typically carry this risk unless there is concurrent COPD or severe prolonged obstruction with respiratory muscle fatigue.

CautionAvoid excessive oxygen that can mask clinical deterioration and contribute to absorption atelectasis. Titrate carefully using continuous pulse oximetry and reassess the patient's work of breathing, not just the SpO2 number.

## 핵심 개념

- **Ventilation-Perfusion Mismatch** — A condition where some alveoli are poorly ventilated but still perfused, causing low oxygen content in arterial blood, common in acute asthma.
- **Absorption Atelectasis** — Alveolar collapse caused by high inspired oxygen concentration washing out nitrogen, which normally helps keep alveoli open.
- **Hypercapnic Respiratory Failure** — Respiratory failure with elevated CO2 levels, a risk in COPD patients when excessive oxygen suppresses respiratory drive.
- **GINA Guideline** — Global Initiative for Asthma guideline that recommends starting oxygen when SpO2 is below 92% and titrating to 93–95% in adults.
- **Pulse Oximetry** — Non-invasive monitoring of arterial oxygen saturation (SpO2), used continuously to guide oxygen titration.

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