Preliminary findings from the investigation into a fatal ambulance fire in Kailua point to a portable oxygen regulator as the cause of the August incident.

A Honolulu Emergency Medical Service ambulance caught fire on Aug. 24 while transporting a 91-year-old patient, Fred Kaneshiro, to Adventist Health Castle Hospital from Kaneohe.

The fire broke out in the hospital parking lot. The 22-year-old paramedic driver was able to escape unharmed, but the 36-year-old paramedic, Jeff Wilkinson, suffered serious injuries and is still recovering in the hospital.

Kaneshiro died in the fire.

The Honolulu Emergency Services Department released preliminary findings on what caused the August ambulance fire during a Tuesday news conference. The fire is currently being classified as accidental, citing the portable oxygen regulator assembly as the possible cause.

“There are no preliminary findings that EMS personnel actions and treating and transporting the patient based on routine industry standard practices contributed to the incident,” said EMS Director Jim Ireland.

“At this time, the precise cause of the fire within the regulator tank mechanism is not known.”

While responding to the August call, the paramedic was using a continuous positive airway pressure (CPAP) machine that was connected to the oxygen supply in the ambulance through a wall port. When the paramedic started preparing to move Kaneshiro from the ambulance to the hospital, he removed the oxygen feed tube from the wall port to connect it to the portable oxygen cylinder. This is standard procedure to ensure that patients will continue to receive oxygen as they are transported from the vehicle to the emergency room on a gurney.

However, when the paramedic connected the CPAP to the portable oxygen supply he described hearing a “pop followed by a bright flash of light,” said Ireland. The ambulance then immediately began filling with smoke and fire.

Ireland said that CPAP machines generally have a life of about five years, but did not know the age of the CPAP being used in the incident. He added that although there is a fire extinguisher on the ambulance, that this particular fire was too large for that to be an option.

“We are looking and reviewing all our policies and procedures to see if there is anything we can do differently if this were to happen again which we hope it never does,” Ireland said.

There are three ambulances that have been pulled out of service that are the same model as the ambulance that caught fire.

“If they are found to be sound and not involved in causing the fire, at some point, we will put those back in service,” Ireland said.

Honolulu Fire Chief Sheldon “Kalani” Hao said the fire investigation included an examination of the incident scene, observed fire patterns, photographs, witness statements and research.

However, beyond this preliminary finding, the investigation is now beyond the scope of the Honolulu Fire Department and all evidence gathered has been turned over back to the Honolulu Emergency Services Department.

In addition to the investigation by city departments, the Emergency Care Research Institute, a private health care safety nonprofit, is also separately looking into the incident. The institute’s preliminary findings also have pointed to the oxygen regulator, but the investigation will continue to focus on what precisely started the fire.

A final report is not expected for several months.