Table 1.

Inclusion and exclusion criteria

Inclusion criteria	Exclusion criteria
Presenting with traumatic pneumothorax/pneumothoraces	Treating clinician(s) believes injuries are incompatible with life
(Believed to be) 16 years and over	Patient in respiratory arrest
Treating clinician(s) believes either a chest drain or conservative management is a suitable initial treatment option	Haemothorax (associated with pneumothorax) requiring a chest drain in the opinion of the treating clinician(s)*
	Clinical or imaging evidence of tension pneumothorax in either lung at the point of randomisation
	Prisoner

Special circumstances: in patients presenting with bilateral chest injury, if one lung of the patient qualifies, the patient can be enrolled, providing no exclusion criteria are met. Treatment of the eligible side follows the randomisation assignment, with the other side treated according to usual practice. If both sides qualify, both sides receive treatment according to the randomisation assignment. Patients who have received prehospital thoracostomies may still be enrolled, provided they fulfil the eligibility criteria. Where a participant who has received a prehospital thoracostomy is randomised to conservative management, local practice should be followed.

*Patients with an associated haemothorax are excluded due to this being a predictor of failure of conservative management.⁵