# Situation: A 22-year-old tall, thin man who smokes is admitted to the surgical ward with a right primary spontaneous pneumothorax. Six hours ago a chest tube was inserted and connected to a three-chamber drainage system with wet suction set at 20 cm H2O. The nurse observes the drainage system. The fluid in the water-seal chamber rises with each inspiration and falls with expiration, bubbles appear in the water-seal chamber only when he coughs, and the suction-control chamber bubbles gently and continuously. How should the nurse classify these findings?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629683  
> 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 22-year-old tall, thin man who smokes is admitted to the surgical ward with a right primary spontaneous pneumothorax. Six hours ago a chest tube was inserted and connected to a three-chamber drainage system with wet suction set at 20 cm H2O.

The nurse observes the drainage system. The fluid in the water-seal chamber rises with each inspiration and falls with expiration, bubbles appear in the water-seal chamber only when he coughs, and the suction-control chamber bubbles gently and continuously. How should the nurse classify these findings?

## 보기

1. Expected findings while a pneumothorax drains **✔ 정답**
2. An air leak at a connection in the drainage tubing
3. Partial blockage of the chest tube by a blood clot
4. Suction pressure set too high for the water seal

**정답: 1**

## 해설

Tidaling in the water-seal chamber shows that the system is open to the pleural space and follows pressure changes with breathing. Intermittent bubbling in the water seal when a client with a pneumothorax coughs or exhales is air leaving the pleural space, and gentle continuous bubbling in a wet suction-control chamber shows that suction is working. Continuous bubbling in the water-seal chamber would mean an air leak.

## 심화 해설

Assessment of a three-chamber chest drainage system

The key to this question is separating what is normal from what signals a problem. In a wet suction system, the water-seal chamber and the suction-control chamber each tell a different story, and the nurse must read both together.

Tidaling — the fluid rising with inspiration and falling with expiration — is an expected finding when the chest tube is patent and the system is open to the pleural space. During inspiration, intrapleural pressure becomes more negative, which pulls fluid up the water-seal tube; during expiration, pressure rises and the fluid falls. This oscillation confirms that the drainage system is communicating with the pleural cavity and is not blocked. The absence of tidaling would be more concerning, as it could indicate a kink, clot, or lung fully re-expanded and occluding the tube openings.

The intermittent bubbling in the water-seal chamber when the client coughs is also expected in a pneumothorax. Coughing raises intrathoracic pressure and forces residual air out of the pleural space through the water seal, producing a brief burst of bubbles. This is air leaving the pleural space, not an air leak. An air leak would present as continuous bubbling in the water-seal chamber, occurring throughout the respiratory cycle and not only with coughing or forced exhalation.

The gentle, continuous bubbling in the suction-control chamber is the expected sign that wet suction is functioning at the prescribed level of 20 cm H2O. In a wet suction system, the depth of the water column in the suction-control chamber determines the amount of suction applied; continuous bubbling indicates that the suction is actively drawing air through that water column. If the suction-control chamber were not bubbling, suction would not be working.

| Chamber | Expected finding | Abnormal finding |
| --- | --- | --- |
| Water-seal chamber | Tidaling with respiration; intermittent bubbling with cough or exhalation while pneumothorax is resolving | Continuous bubbling (air leak); absent tidaling (obstruction or lung occluding tube) |
| Suction-control chamber | Gentle continuous bubbling while suction is on | No bubbling (suction not functioning); vigorous bubbling (suction may be set too high) |
| Collection chamber | Drainage amount monitored; level marked | Sudden increase in bright red drainage (hemorrhage) |

Watch out! Continuous bubbling in the water-seal chamber is the hallmark of an air leak — either from the patient’s pleural space or from a loose connection in the tubing. To locate the source, briefly clamp the tube near the insertion site: if bubbling stops, the leak is inside the patient; if bubbling continues, the leak is in the tubing or drainage unit.

Key point! Tidaling stops when the lung fully re-expands or when the tube is occluded. Always correlate the water-seal findings with the client’s respiratory status, breath sounds, and chest imaging rather than interpreting the chamber in isolation.

The scenario describes a 22-year-old tall, thin male smoker, which is the classic demographic for a primary spontaneous pneumothorax due to rupture of subpleural blebs. Six hours after chest tube insertion, the lung is still in the process of re-expanding, so intermittent air evacuation with coughing and preserved tidaling are entirely consistent with a functioning drainage system actively removing residual pleural air. The combination of findings — tidaling, cough-induced bubbling, and continuous suction-control bubbling — represents the expected pattern while a pneumothorax is draining.

## 임상 시나리오

Chest Tube Drainage Assessment: Wet Suction SystemExpected vs. Abnormal Findings in Pneumothorax
Tidaling in the water-seal chamber—fluid rising with inspiration and falling with expiration—confirms the system is patent and open to the pleural space. Absent tidaling suggests kink, clot, or lung re-expansion occluding tube openings.

Intermittent bubbling in the water-seal chamber with cough or forced exhalation is expected when a pneumothorax is draining—it represents air leaving the pleural space. Continuous bubbling throughout the respiratory cycle indicates an air leak in the system or persistent pleural air leak.

Gentle continuous bubbling in the suction-control chamber confirms wet suction is functioning at the prescribed level (e.g., 20 cm H2O). Absence of bubbling means suction is not being delivered.

CautionNever clamp the chest tube to assess for air leak unless ordered—clamping can cause tension pneumothorax in patients with active air leak. Document tidaling, bubbling pattern, and suction chamber activity every 1–4 hours and with any change in patient status.

## 핵심 개념

- **Tidaling** — Fluid in water-seal tube rising with inspiration and falling with expiration, indicating system patency and communication with pleural space
- **Water-seal chamber** — One-way valve chamber that allows air to exit pleural space while preventing air from re-entering; intermittent bubbling with cough/exhalation is expected
- **Suction-control chamber** — Chamber in wet suction system that regulates suction pressure; gentle continuous bubbling indicates suction is functioning properly
- **Air leak** — Continuous bubbling in water-seal chamber throughout respiratory cycle, indicating system breach or persistent pleural air leak
- **Primary spontaneous pneumothorax** — Air in pleural space without trauma or underlying lung disease, common in tall thin young male smokers

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