As South Korea grapples with a medical service vacuum in hospitals over a week after residents walked out in protest against the government's plan to increase the annual medical enrollment quota, nurses started filling the void Tuesday despite the lingering uncertainties over legality issues.

The government launched a pilot project for physician assistant nurses working in general hospitals and training hospitals nationwide. Starting Tuesday, heads of each health care organization can determine the scope of work PA nurses can perform.

However, nurses fear that despite the government's announcement, as this is a pilot project, which can be implemented temporarily and then disappear, they could be subject to legal pitfalls. Complaints over being overworked also remain, as nurses are being asked to "take over the work left by the walk-out doctors in addition to their existing duties."

"Because there are no doctors to accompany patients in case of emergency during patient transportation, nurses were told to take over the task while the working hours which used to be until 7 p.m. have been extended to 10 p.m.," one nurse who has been working at a major general university hospital for 10 years told the Korea Herald, wishing to stay anonymous under surname Park.

"PAs have been prescribing medication using the doctors' IDs, knowing that they wouldn't be protected if there were problems with the patient's safety. However, because there is a shortage of doctors in the field, such incidents have occurred frequently with no choice," Park added.

PAs are nurses who partly take over the duties of doctors in medical institutions and have been called clinical nurse specialists or operating room nurses. They perform the general tasks normally undertaken by residents, such as prescribing medication, conducting tests and performing partial surgeries.

Well institutionalized in the United States and other countries, however, the roles of such nurses are not stipulated in the Korean medical law system. As there is no separate physician assistant license under the Medical Service Act, it is technically illegal for physician assistants to practice medical procedures that would normally be conducted by the physicians themselves. According to the Medical Service Act, nurses are only allowed to assist in medical treatment under the guidance of doctors.

Meanwhile, due to a deep-seated shortage of doctors, such nurses have undertaken such tasks by tacit agreement, and are often referred to as "the ghosts" at hospitals. There are currently around 10,000 physician assistants. PAs have been used at the individual hospital level since the early 2000s.

"PA nurses are like ghosts in Korea. They exist but they don't," said Jeong Hyung-jun, chair of the policy board at the Korean Federation of Medical Groups for Health Rights to the Korea Herald.

"PA nurses have been filling the gap of doctor shortages already, taking on important tasks in the hospital. But as they are not protected under the current medical law, they fall into a gray area."

Despite the government's pilot project, nurses cannot perform tasks that are classified as "acts requiring advanced knowledge and skills" by the Supreme Court. Spinal anesthesia, anesthesia using propofol, and death diagnoses are prohibited by Supreme Court precedent, according to the Health Ministry.

Medical communities also are concerned about frontline nurses suddenly being used as medical assistants without any related education or training.

At a press conference held by the medical workers' union on Monday, cases such as the formation of a CPR team in hospitals without a doctor, where nurses perform chest compressions directly, and cases where nurses issue proxy prescriptions under a doctor's ID, create medical records, and disinfect sutures and hemostasis in surgery were reported.

Jeong voiced that the distribution of work between doctors and nurses is inevitable as technology and medical levels advance, stressing that establishing legal grounds for PA nurses is crucial in solving the shortage of resources in hospitals.

Meanwhile, some residents seem to be resuming work, according to the government on Tuesday, adding that it has completed a legal review to take judicial action against those who have not returned.

"It's difficult to compile accurate statistics, as verifying whether (the residents have) returned to work is not easy," said Second Vice Health Minister Park Min-soo, yet he hinted optimistically that "quite a few residents are returning to some hospitals."

Some 9,909 doctors at 9 major training hospitals have submitted resignation letters, or equivalent to about 80.6 percent.