Four in 10 cardiac arrest incidents went unnoticed by private ambulance crewmen when they responded to non-emergency calls, a new study has found.
Efforts to resuscitate these patients were also delayed in some instances despite the crew having identified the symptoms.
The findings, published in the latest edition of local medical journal Annals Academy Of Medicine last month, examined non-emergency ambulance arrivals at six public hospitals from 2002 to 2009.
Figures show that 86 patients, with an average age of 63, were found to be in cardiac arrest by the time they pulled into the emergency department of a public hospital.
Almost half of these cardiac arrest cases were not spotted by medics on board private ambulances and these patients, say researchers, could have suffered the abrupt loss of heart function in transit.
And of the 48 patients whose cardiac arrests were recognised, a third did not receive cardiopulmonary resuscitation (CPR) en route to an emergency department.
Finally, only three of the 86 cases survived the trauma and were discharged.
Lead author Nausheen E. Doctor of Singapore General Hospital said the delays in recognising the condition and resuscitating patients were a concern.
Applying CPR can buy time for patients - the earlier, the better. Every minute of delay lowers the patient's chance of survival by up to 10 per cent, said the emergency medicine specialist.
These findings prompted the researchers to call for better training of medics, regulations for the industry and public education.
The Ministry of Health (MOH), in fact, has already started work on several fronts to raise the standards of ambulance services.
In 2009, the ministry led a workgroup which formed a Pre-Hospital Emergency Care Transformation Plan that applies to both the public and private ambulance sectors.
The plan aims to strengthen the delivery of care before a person reaches the hospital. The MOH and the Ministry of Home Affairs in 2011 formalised a pact to oversee the implementation of the plan.
One key component is the expansion of the Healthcare Support Workforce Skills Qualifications (WSQ) framework to include a new certificate for emergency medical technicians.
The Singapore Workforce Development Agency, which oversees the certification scheme, is working with SingHealth's Alice Lee Institute of Advanced Nursing to develop the training course, known as the WSQ Higher Certificate in Healthcare Support (Pre-Hospital Emergency Medical Services). The two-month programme will equip participants with the skills to manage patients with diverse medical conditions.
The MOH has also worked with the Institute of Technical Education (ITE) College East to start a course last December for existing paramedics to refresh their skills and update them on the latest developments.
There are 337 private ambulances that mostly respond to non-emergencies as of Sept 30, said the Land Transport Authority.
The Singapore Civil Defence Force (SCDF) runs a fleet of 50 emergency ambulances, including 20 belonging to private operators.
Data from five public hospitals showed that in July last year, between 5.4 per cent and 28.2 per cent of patients arrived at their emergency departments in private ambulances.
Not every private ambulance carries an automated external defibrillator, which treats patients by applying an electrical shock.
Many vehicles operate with a crew comprising a driver and an assistant trained in basic cardiac life support. Others have nurses, paramedics and doctors on board.
Emergency ambulances, however, are all equipped with defibrillators, said the SCDF. Mechanical chest compression devices are also on board to take over the task of applying CPR manually.
But it is not difficult to monitor a patient's vital signs in the vehicle, said Dr Madeleine Chew, founder of home medical service provider MW Medical, which runs three ambulances, usually with a doctor or a nurse.
She suggested a possible reason for the missed cases: The patients' initial complaints were "very far" from a clear-cut emergency, such as back pain, and the staff in attendance became complacent.
Dr Chew added that her agency screens calls from the 1777 hotline for potential emergencies. "If the person has, for example, a previous history of heart problems or chest pain, we will divert the case to an emergency ambulance," she said.
In the meantime, guidelines for the private ambulance sector, dating back to 1998, are being updated. The review seeks to "strengthen the medical standards and competency requirements" of the sector, said the MOH last week.
The ministry will be holding industry consultations before rolling out the guidelines, and private ambulance operators will be included in the process.