Content Note: This story contains discussion of medical procedures.

• Complications, not misadventure, caused death
• A “dirty” protamine drug caused side effects
• Blood loss not caused by leg drainage

Carmen Walker’s death at Waikato Hospital after a cancer procedure was caused by an adverse reaction to a “dirty” drug as well as blood loss, a coroner has found.

However, the blood loss was not due to excess blood draining from Walker’s body during the procedure, but more likely a combination of other bleeding, coroner Alexander Ho said.

Coroner Ho, who released his findings into the 2010 death on Friday, found that Walker, 78, died from complications related to the isolated limb perfusion (ILI) procedure to treat melanoma in the leg.

It involved blood loss and an adverse reaction to protamine – a medication used at the end of a procedure to reverse blood thinning medications.

The source of the blood loss was unknown but could have included any combination of gastrointestinal bleeding, internal bleeding, expected ILI blood loss and external bleeding, the coroner said Ho.

The ILI procedure involves cutting off circulation to the diseased leg with tourniquets, injecting melphalan, a chemotherapy drug, into the leg to “bathe” the cancer cells, washing the limb to remove the drug and contaminated blood, and then to release the tourniquets.

Coroner Ho said the “unlikely coincidence of two relatively rare events” had to be assessed against three elements:

• The high incidence of adverse reactions to protamine, i.e. one in 10;
• The fact that Walker’s blood pressure only plummeted after she received the first small dose of protamine;
• And that there was no evidence of significant blood loss until she suffered cardiac arrest.

At this point, a second arterial blood gas test showed that Walker had a very low hemoglobin level of 28, later judged by a pathologist to be incompatible with life.

An earlier image of his heart showed the left ventricle “very empty”, indicating hypovolemia – when the body loses fluids such as blood and water.

The coroner ruled out that the tourniquets were not working properly.

An unrecognized tourniquet leak could have allowed all of Walker’s circulating blood to seep into the leg and drain out of his body while the limb was being washed without anyone noticing.

But the bucket used to collect sewage did not provide measurements, and the senior surgeon – whose name was withheld – told the inquest that measured buckets were previously used, but resource constraints led to their disappearance.

Coroner Ho said resource constraints were outside the scope of the inquest and ILI procedures were no longer practiced in New Zealand so he could not make specific recommendations.

“Nevertheless, I observe that for procedures involving a blood drainage component, it would be prudent to drain it into a measurable container.”

The coroner accepted the testimony of the anesthesiologist – whose name is also withheld – that it was reasonable to consider adverse reactions as the likely cause of Walker’s accident.

He said her age and physical condition — although fit and active, she had hardened arteries and took beta blockers for high blood pressure — inhibited her ability to tolerate and recover from complications.

The coroner found that the surgeon and anesthetist did nothing wrong, including during the marathon 90-minute resuscitation.

“Ms. Walker’s death occurred despite, not because of, the decisions that were made regarding her resuscitation.”

Coroner Ho also noted that the decision of on-call critical care specialist Dr. John Torrance to provide end-of-life care instead of administering the remainder of the protamine to stop Walker’s bleeding was correct.

However, the pathologist who changed his findings about Walker’s cause of death, prompting the solicitor general to reopen the investigation, was criticized in the 47-page report.

Dr Ian Beer carried out Walker’s autopsy without his medical notes, which the inquest heard was not acceptable medical practice, and the coroner preferred the testimony of a former first-year healthcare doctor intensive investigations regarding potential gastrointestinal bleeding rather than Beer’s testimony that he found none. .

Walker’s family told RNZ they were shocked and disappointed by the discovery.

Te Whatu Ora Waikato acknowledged the results and said it recognized Walker’s enormous loss.

Chronology

• August 3, 2010: Carmen Walker undergoes surgery at Waikato Hospital and dies.
• August 4, 2010: Pathologist Ian Beer conducts an autopsy without hospital notes and concludes that Walker died from cardiogenic shock.
• April 20, 2011: Coroner Gordon Matenga conducts a “papers hearing” and makes the same conclusion.
• May 2011: Dr. Adam Greenbaum files a complaint with the Health and Disability Commissioner and sends a copy to the medical board.
• January 2013: The Waikato DHB’s internal review finds no definitive cause of Walker’s death, but there was a possible leak in the tourniquet and the fluid washing from his leg was not measured.
• December 2013: Health and Disability Commissioner Anthony Hill believes Walker’s care was “suboptimal” but takes no further action.
• March 2019: Greenbaum and the Walker family are asking the solicitor general for a full coronary investigation.
• August 2020: Deputy Solicitor General Virginia Hardy refuses an investigation.
• April 2021: Beer requests the hospital notes from HDC but is refused.
• May 2021: Greenbaum provided Beer with part of the HDC investigation, including an Australian expert’s report that Walker died of hypovolemic shock.
• May 13, 2021: Beer writes to the coroner to have the cause of death changed.
• May 27, 2021: Chief Coroner Judge Deborah Marshall writes to the Solicitor General to request the case be reopened.
• June 1, 2021: Solicitor General Una Jagose orders further investigation.
• November 2021: Coroner Alexander Ho orders an inquest.
• August 2023: The investigation takes place over three weeks in Hamilton.
• October 2024: Results published.