Cardiogenic and obstructive shock: Case

This adolescent has developed a tension pneumothorax on the right side while ventilated for severe asthma. The sudden hypotension, tachycardia, desaturation, high ventilator airway pressures, absent right-sided breath sounds, and distended neck veins are the classic presentation of tension pneumothorax in a ventilated patient. Positive-pressure ventilation converts a simple pneumothorax to a tension pneumothorax rapidly, and this is a time-critical emergency requiring immediate decompression. [1][7]

Clinical findings

The pattern is that of obstructive shock from tension pneumothorax. The rising intrathoracic pressure from the trapped air has collapsed the right lung, pushed the mediastinum to the left, compressed the great vessels, and blocked venous return to the heart. The distended neck veins reflect the backed-up venous return, the hypotension reflects the loss of preload, and the high ventilator pressures and desaturation reflect the collapsed lung and the compressed pulmonary vasculature. The diagnosis is clinical in this scenario and imaging must not delay treatment. [1]

The differential at the moment of deterioration includes a blocked or displaced endotracheal tube, which can produce similar high pressures and desaturation, but the unilateral absent breath sounds and the distended neck veins point to tension pneumothorax. A mucus plug causing right lung collapse can also produce unilateral absent sounds, but it would not typically cause the distended neck veins and the sudden haemodynamic collapse. [7]

Investigations and diagnosis

The diagnosis is tension pneumothorax. In the unstable, deteriorating ventilated patient, the diagnosis is clinical and decompression must precede imaging. Once the child is stabilised after decompression, a chest X-ray confirms the pneumothorax, the mediastinal shift, and the position of the chest drain. A point-of-care lung ultrasound, if immediately available and the operator is skilled, can confirm the absent lung sliding and the lung point at the bedside, but it should not delay decompression in the crashing patient. [6]

Management and outcome

Management is immediate decompression. The clinician first checks that the endotracheal tube is patent and correctly positioned, because a blocked tube is the other cause of sudden high pressures and desaturation. Once the tube is confirmed patent and the clinical picture of tension pneumothorax is clear, the clinician performs a finger thoracostomy at the fourth or fifth intercostal space in the anterior axillary line on the right side. Finger thoracostomy is preferred over needle thoracostomy in the ventilated patient because it provides immediate, reliable drainage and allows a formal chest drain to be inserted through the same incision. [6]

The Ahmad 2025 meta-analysis confirmed that the traditional second intercostal space mid-clavicular line needle decompression site often fails because standard cannulae are too short, particularly in larger adolescents and adults, and recommends the fourth or fifth intercostal space in the anterior axillary line as the more reliable site. The clinician inserts a formal intercostal chest drain connected to an underwater seal, and confirms the position and the lung re-expansion on a chest X-ray. [6]

For the fluid strategy, the clinician gives a cautious 5 mL per kg bolus of isotonic crystalloid as a bridge, recognising that this is obstructive shock and that the definitive treatment is the decompression. Once the chest is decompressed and the right lung re-expands, the airway pressures fall, the oxygen saturation improves, the venous return is restored, and the blood pressure recovers. The girl is transferred to the PICU for ongoing asthma management and ventilator weaning, with the chest drain left in situ until the air leak resolves. [1][7]

The long-term management addresses the severe asthma, with a written asthma action plan, preventer therapy, and follow-up with a respiratory physician to prevent a recurrence of the life-threatening presentation. The family is debriefed on the events and the warning signs of deterioration. [7]