Date: February 11th, 2020

Reference: Yeh et al. Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial. BMJ 2018.Guest Skeptic: Marcus Prescott is a nurse in Norway. He is also now a third-year medical student.Case: A 32-year-old woman with no previous medical history calls you while a passenger on a crashing plane. She has been offered a parachute by the flight attendant but is unsure whether jumping from the plane is wise. You quickly scour the literature for evidence to inform her decision.

Background: The parachute– an umbrella term for devices to slow the motion of an object through an atmosphere by creating drag – was first deployed in China roughly 4,000 years age. The modern versions reached widespread use with the invention of heavier than air flight early last century.

Different variants of parachutes have been used both for recreational and safety purposes; in either case aiming to avoid death in people falling from heights presumed to be lethal. Despite the near universal application, a systematic review from 2003 (Smith and Pell, BMJ) found no RCTs of parachute intervention.

That systematic review published in the BMJ is a classic paper and part of their annual holiday edition. It stated that there was observational data showing parachutes failed at times to prevent morbidity and mortality. There are also case reports of free falls that did not result in 100% mortality.

The authors suggested taking evidence-based medicine advocates up in a plane for a double blinded randomized control trial. The intervention would be a parachute and the control arm would be a sham parachute (backpack). To make it more rigorous, anyone who survived the first jump would cross over into the other arm of the study and jump again. Only then would we have definitive evidence that a parachute was effective in preventing death and major trauma related to gravitational challenges.

After years of trying to organize a trial, researchers were finally able to recruit some volunteers to jump out of a plane with a parachute or backpack.

Clinical Question: Do parachutes reduce death or major injury when jumping from aircraft?

Reference: Yeh et al. Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial. BMJ 2018.

Population: Adults 18 years of age and older, seated on aircraft and deemed rational decision makers.Intervention: Jumping from aircraft with parachuteComparison: Jumping from aircraft with backpackOutcome:

Primary Outcome: Composite of death and major traumatic injury (ISS>15) within five minutes of impact or at 30 days.Secondary Outcomes: Health status and subgroup analysis based on type of aircraft or previous parachute use.

Authors’ Conclusions: “Parachute use did not significantly reduce death or major injury when jumping from aircraft in the first randomized evaluation of this intervention. However, the trial was only able to enroll participants on small stationary aircraft on the ground, suggestion cautious extrapolation to high altitude jumps. When beliefs regarding the effectiveness of an intervention exists in the community, randomized trials might selectively enroll individuals with a lower perceived likelihood of benefit, thus diminishing the applicability of the results to clinical practice.”Quality Checklist for Randomized Clinical Trials:

The study population included or focused on those in the emergency department. NoThe patients were adequately randomized. YesThe randomization process was concealed. YesThe patients were analyzed in the groups to which they were randomized. YesThe study patients were recruited consecutively (i.e. no selection bias). NoThe patients in both groups were similar with respect to prognostic factors. UnsureAll participants (patients, clinicians, outcome assessors) were unaware of group allocation.