Chest drain: continuous or intermittent suction
7 kg Maltese with pneumothorax after being bitten on the chest by another dog. It has a chest drain aspirated every 2 hours: each aspiration yields large volumes of air and between aspirations it becomes tachypnoeic again.
What is the best option for managing the drain now?
chevron_right Show answer and explanation
A. Fit a Heimlich valve so the air can escape on its own
The Heimlich valve needs the patient to generate enough intrathoracic pressure to open it: it is not recommended in animals under about 15 kg or with fluid, which blocks it.
B. Clamp the drain for 12 hours so the leak can seal
Clamping a drain with an active leak lets air accumulate and can cause tension pneumothorax.
C. Continuous suction with a chambered water-seal drainage system
Correct. When air production exceeds what can be removed by intermittent aspiration, continuous low-pressure suction (around −10 to −20 cmH2O) keeps the lung expanded and helps the leak seal. It requires constant monitoring of the connections.
D. Space the aspirations to every 6 hours to give the lung time to heal
Letting air accumulate for longer worsens hypoxaemia and collapses the lung, which does not help the leak seal.
lightbulb Key takeaway
If the air leak persists despite continuous suction for several days (usually 3–5) or the patient deteriorates, consider thoracotomy or thoracoscopy. Thoracic bite wounds usually have more damage than is visible on the skin and often need surgical exploration.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.