Industry Voice: Medical training in a hypobaric chamber

In 2018 and 2019, the decision was made to use a hypobaric chamber to allow the team to practise simulated resuscitation in flight. Conducting simulated ALS techniques at 9,000 ft added stressors of flight to the scenario, like bariatic pressure, reduced oxygen, noise and confined space, all without leaving the ground.

Role of the AMU

The AMU provides aviation medicine training and advice to the Royal New Zealand Air Force. AMU training is varied, but it is focused on those who work in the sky; one of those roles is aeromedical evacuation (AE). AE training is conducted from AMU’s state-of-the-art training facility at Whenuapai, Auckland, New Zealand.

training is conducted from AMU’s state-of-the-art training facility at Whenuapai, Auckland, New Zealand

AMU’s hypobaric chamber came into service in 1968. It has a main chamber that can hold 14 students and two instructors, and is normally used for hypoxia training; it has an intermediate lock used for rapid decompression.  

As AE patients are extremely vulnerable, realistic AE training is crucial, as even the smallest mistakes can have immense consequences. To prepare for the worst case, training scenarios practising ALS in flight teach how to prevent ‘the Swiss cheese model’ lining up. Responsible training calls for an awareness of cost and impact on the environment. However, the aviation environment is unique and aeromedical clinicians must actually experience it to properly understand it. AMU decided to innovate its ground training techniques in order to better prepare its clinicians for air medical evacuation missions. Squadron Leader and Flight Medical Officer Gus Cabre said: “We use a program of evolving simulation to prepare our people for flight; [and] it occurred to us that we use the hypobaric chamber to train aircrew in aviation emergencies, so it was a natural progression to also train our clinicians for emergencies while experiencing the stressors of flight.”

A unique environment

In an aircraft, clinical skills and teamwork in a moving, noisy and confined space are challenging when things are going well. When they are not, dangers await. Hazardous circumstances are difficult to create in classroom lectures and with ground training. The hypobaric chamber replicates the aviation environment with the difficulties of communication and restriction of movement. The only way to overcome these problems is with effective teamwork.

Corporal Leigh Douglas added: “When learning how to safely transfer patients by flight, clinicians must learn and consider how the stressors will be a factor; the chamber makes you consider these factors not only for your patients, but also for yourself.”

When learning how to safely transfer patients by flight, clinicians must learn and consider how the stressors will be a factor; the chamber makes you consider these factors not only for your patients, but also for yourself

Crew resource management (CRM) is fundamental on an AE mission. Even the most junior team member must feel free to speak up about medical or aviation safety concerns. Worries are debriefed after every scenario, and all students are expected to contribute. Students have more feedback to offer after realistic experiences; these opinions assist in everybody’s learning and inspire (operational CRM).

Fresh thinking takes the students out of the classroom in the afternoons. The heavy cognitive load is delivered in the morning while the ‘hands-on’ experience learning is provided in the afternoon. A cardiac arrest ‘in flight’ (in the chamber) certainly wakes the students from their post-lunch mental slump. This fresh thinking proved popular with both students and instructors, which enhanced everybody’s learning.

Passion is a key ingredient to succeed in AE. Proper training can help avoid making mistakes under pressure. Putting students under stress with realistic scenarios brings out the best in them. You can see this in their faces when the chamber door closes and the pump starts. You can hear this with passion when they talk about the experience.

Training scenarios

In our latest training exercise, we ran two different scenarios. One was an airway/respiratory arrest and the other cardiac arrest. For the airway one, we trained our people to the VORTEX method and for the cardiac arrest we used the New Zealand Advanced Cardiac Life Support (ACLS) guidelines from the New Zealand Resuscitation Council.

Personnel

In the chamber were a chamber supervisor, chamber controller, chamber operator, run recorder, internal instructor and internal observer (safety). 

Equipment

NATO stretcher, five-point harness, SIM man (high fidelity model, controlled by an instructor with a tablet who is inside the chamber), oxygen, (ARK med pack) with HM), Sp02,  oropharyngeal airway, BVM, LMA, Zoll defibrillator/lead set with SIM leads (ready to use), IV kit and SIM drugs.

Chamber SIM

These sessions run as a round robin, there is 20 mins for each and a total of six (other) different activities. The participants are expected to move quickly between activities as directed by their instructors.

Each team task is to be directed by a different team leader. Participants take turns at leading the group, identifying the team leader to the instructors at the start of the exercise. This is to practice CRM, so the most senior or experienced person is not always in charge.  

The SIM is run in the chamber at 9,000 ft, and the lights are dimmed as they would be in an aircraft. All students must pass a hypobaric medical before participating. The team leader will have a headset through which they communicate with instructors and relay information to their team. The rest of the team wears hearing protection only, which mirrors the current issues crewmembers have in the NZ Air Force C-130, where communication for the whole team is not available. Equipment will be put inside the chamber for the team to use, and CCTV will be used to record the SIM for feedback purposes.

Highlighting the value of the training, Flight Nursing Officer Major David Greenhough said: “Using the chamber for ACLS simulation compounds physiologic and psychologic stress, knowing when you are at altitude you just can’t walk out, just like an aircraft, it brings the scenario as close to real as you can, while still remaining on the ground.”