A super-dose of chemo was supposed to buy more time for Carmen Walker.

The malignant melanoma in the right ankle of the otherwise fit 77-year-old had returned, with tentacles that quickly spread up her leg.

The cancer had not spread to the rest of her body. Yet.

It was a matter of when, not if, she would succumb to the disease.

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The prognosis was grim but the cheerful, outgoing woman once recognised as one of the most positive people in Whanganui kept a smile on her face.

It certainly didn't stop Carmen Walker from delivering meals-on-wheels, as she had for the past 25 years.

Amputation was suggested for the former competitive swimmer, but removing the limb would only delay the inevitable.

Instead, in a bid to improve the quality of life for her remaining years, Walker decided to undergo treatment called isolated limb infusion (ILI).

The cancer in the affected limb only is "bathed" in highly concentrated chemotherapy, without the toxic agents flowing through the whole body.

The palliative treatment is uncommon in New Zealand and not without risk, like any complex procedure.

Everyone thought Walker would emerge unscathed smiling a few hours later, hopeful the treatment had worked and able to enjoy the time she had left.

Instead, she bled to death.

"It was unbelievable to be perfectly honest," her son Craig Walker says. "We were in absolute shock."

The circumstances of her death in August 2010 raised many questions for the Walker family.

Eight years later, Craig and his wife Linda are still grappling with the answers.

No one disputes Walker died from massive blood loss.

But the shortcomings in her care mean there is no way of establishing exactly what caused the fatal bleeding.

"We feel the medical profession is an old boys' club where everyone looks after one another," Craig Walker says.

He found an unlikely ally in Dr Adam Greenbaum, one of the doctors who observed the procedure and was involved in the unsuccessful efforts to resuscitate Walker.

Consultant plastic and reconstructive surgeon, Adam Greenbaum. Photo / Alan Gibson
Consultant plastic and reconstructive surgeon, Adam Greenbaum. Photo / Alan Gibson

A consultant plastic surgeon from the United Kingdom, Greenbaum had never performed ILI but was familiar with a slightly different procedure known as isolated limb perfusion.

He insisted on being trained in ILI before undertaking one himself.

However, the plastic surgeon normally responsible for ILI at Waikato Hospitalwas unavailable, so another doctor conducted the procedure in his stead.

He had previously performed nearly all the limb infusions at the Waikato DHB before going into private practice in 2005.

It's not a surgical procedure as such; the consultant surgeon acts as a conductor of the medical team which includes a perfusionist, anaesthetist, radiologist and nurses.

Normal chemotherapy treatment attacks healthy and sick cells throughout the entire body alike. But with ILI, doctors cut off the circulation to a limb with two tourniquets and infuse a highly concentrated chemotherapy agents to "bathe" the cancerous cells.

The stronger dose would be toxic if it flowed through the whole body like regular chemotherapy. But with the tourniquets in place, the concentrated chemotherapy can be given directly to the affected limb with only a small amount escaping into the patient's circulation system.

The tourniquets also stop oxygenated blood flowing from the heart into the limb, so a bypass machine is used to maintain circulation.

At the end of the treatment, the tainted blood is drained into a waste bucket and the limb "washed out" with solution before the tourniquets are released.

It's an ideal treatment for a small group of patients, Greenbaum says.

"With chemotherapy where the cancer has spread, you have to take the rough with the smooth. It makes you feel sick, your hair falls out, your whole body is affected," Greenbaum says.

"With ILI, the treatment is only affecting the one limb. The rest of the body isn't being damaged, so you can improve quality of life. Some of these patients live for years."

Carmen Walker was considered an appropriate candidate.

Radiation and surgery to remove lesions failed to halt the melanoma creeping up her leg, but she was not keen on amputation.

Walker with her husband Bob. Photo / Supplied
Walker with her husband Bob. Photo / Supplied

Neither was her oncologist who said removing her leg would not improve her life expectancy or quality of life.

She was referred to Waikato Hospital which was the only publicly funded centre in the country to offer ILI at the time.

Craig Walker drove his mother, and father Bob Walker, to discuss the risks with the surgeon in his Hamilton offices in June 2010.

Death as a potential outcome was not raised at the meeting, Bob and Craig Walker later claimed during the Health and Disability Commission investigation.

"We thought losing her leg was the worst-case scenario," he told the Weekend Herald.

This was disputed by the surgeon and the consent form signed by Walker does list death as a specific risk.

Nevertheless, she decided to go ahead. Two months later she was admitted Waikato Hospital.

"We said goodbye in the ward and Mum said 'I'll see you afterwards'," Craig Walker says.

"We waited and waited and waited."

The procedure got off to a slow start. The radiologist took nearly two hours to insert the catheters into the cancerous leg, because Walker's veins and arteries were hardened with calcification.

This was only a mild concern at the time, the surgeon later wrote in his report to the Coroner, and the radiologist was "very happy" with the final placement of the catheters.

The rest of procedure went to plan and, after "bathing" the cancerous cells for about 20 minutes, the "washout" started.

The tainted blood is flushed out of the limb into a bucket until the effluent fluid runs clear.

Dr Greenbaum, who was observing the procedure, happend to look into the "washout" waste bucket.

"I said: 'There's an awful lot of blood in there'. And I was told it was normal, it looked like a lot of blood but it was actually fluid from the washout," Greenbaum told the Weekend Herald.

After the washout cycle, the lead surgeon released the tourniquets and Walker's blood pressure dropped.

This was normal, although the inner tourniquet was re-inflated to slow the release of any remaining chemotherapy into the rest of her body.

Her blood pressure recovered, so the tourniquet was released again and Protamine administered to reverse the effect of the blood thinner Heparin.

Immediately, Walker's blood pressure dropped and continued to fall over the next 20 minutes.

At 5.30pm, her heart stopped.

There wasn't enough blood in the left chamber of her heart, according to an ECG, and the doctors tried to resuscitate her.

Sitting in her room on the ward, Craig and Bob Walker were wondering what was taking so long.

"We waited and waited and waited, until Adam [Greenbaum] and the anaesthetist came out to say it was serious," Craig Walker says.

"It was life and death."

After an hour and a half of resuscitation, his mother had regained a strong enough heartbeat to be transferred to the Intensive Care Unit.

"We didn't know whether she'd survive," Craig Walker says, "but it soon became obvious it was the beginning of the end."

He noticed a red patch on the bed, so lifted up the blanket covering his mother.

"She was lying in a pool of blood, the bed was just covered in blood," he claimed.

He asked the nurses to change the sheets.

Walker with sons Craig and Lane Walker. Photo / Supplied
Walker with sons Craig and Lane Walker. Photo / Supplied

"We went back in to sit with her. Then she passed."

It was 11.15pm.

Her death was considered a "sentinel event" to be investigated internally at the Waikato DHB, as well as referred to the Coroner.

In his report to Coroner Gordon Matenga, the surgeon who lead the procedure noted the "washout" bucket was "unusually full".

He estimated there was about 3 to 4 litres of fluid but there was no way of telling what was blood, or other fluids used in the ILI procedure. It hadn't been measured.

An autopsy report could not find any source of significant blood loss and, although there was blood in her rectum - an indicator of internal bleeding - the volume was unknown.

This raised the important question of whether the extra fluid in the waste bucket was actually Walker's blood, the surgeon wrote. Had the life literally drained out of her into a bucket?

"The only explanation I can think of was that the tourniquets were not sufficiently compressing the arterial blood supply to the limb, allowing arterial blood to leak into the limb as we were washing out the venous system," the surgeon told Coroner Matenga.

"I think this must be considered high on the list as a possible contributing factor."

The tourniquets may not have cut off the circulation completely because of the hardening of the Walker's arteries, which had earlier made it difficult to insert the catheters.

Though the autopsy noted the disease of the arteries was "severe", the pathologist did not dissect the blood vessels.

This would have been "illuminating", said the surgeon, to see whether the tourniquets could have compressed Walker's arteries.

To minimise the chances of another death like Walker's, the surgeon suggested making some changes.

These included using an ultrasound test to double-check the tourniquets worked and more accurate measurement of the fluid drained in the washout phase.

Instead of holding an inquest, Coroner Matenga determined the cause of death for Walker on the basis of the surgeon's report and the autopsy.

He ruled she died of "cardiogenic shock" - where the heart suddenly can't pump enough to meet the body's needs - according to the seven-paragraph ruling released in April 2011.

The Coroner did not examine why this happened, or whether the care given to Walker was satisfactory.

The decision was made before the internal investigation at the Waikato DHB had started.

By this point, Greenbaum had left the DHB.

He was alarmed no one had spoken to him about the internal investigation in the death, although Dr Chris McEwan - the unavailable ILI expert - reassured him it would be robust.

But when the audit nurse spoke to Dr McEwan to seek his advice on the case, she was unaware Greenbaum was in the room as an observer.

This was despite Greenbaum claiming he wrote into the clinical record several times and the presence of a student nurse, on training, was recorded.

A month after the Coroner's report, Greenbaum wrote to senior DHB managers Dr Tom Watson and Dr Winston McEwan - no relation to Chris McEwan - with his concerns.

"I find it inexplicable that it was only when Chris McEwan mentioned I had been present ... and suggested that she should check facts with me, that she became aware of my existence, let alone my involvement on the day," Greenbaum wrote.

In his opinion, Walker's death was avoidable. Greenbaum told the DHB managers he expected to be interviewed as part of the investigation.

If not, he would notify the Health and Disability Commission.

Greenbaum never heard back.

So he did make a complaint - highlighting his exclusion from the internal investigation and the inference his entries into the medical notes had been removed - with the HDC.

When they were later told about Greenbaum's complaint, Bob and Craig Walker remembered him. He had spoken to them twice on the night Walker died.

They supported the complaint.

"Something had obviously gone wrong," Craig Walker says. "But we didn't know how badly wrong until [Greenbaum] came forward."

However, muddying the waters, was Greenbaum's acrimonious departure from the DHB which led to an out-of-court settlement.

Patient care, not malice, was not the motivation for the complaint, insists Greenbaum who was upfront about the fallout with the HDC.

But with the legal battle in the background, hospital management described Greenbaum as "aggressive, threatening, litigious and vexatious" when the HDC told them of the complaint.

"The matter referred to you has been the play-out of that," chief executive Craig Climo wrote to Anthony Hill, the Health and Disability Commissioner.

"Thankfully Dr Greenbaum no longer works here but it seems his vindictiveness remains."

On a separate issue, Greenbaum and a fellow plastic surgeon had complained to the Medical Council about a senior colleague.

In a counter-claim, the DHB raised concerns with the Medical Council about Greenbaum.

The concerns about Greenbaum were dismissed by the Medical Council which decided he did not required to undergo a performance review. They also granted his application for vocational scope of practice, despite the opposition of the DHB.

These issues were canvassed in a letter from Medical Council chief executive Philip Pigou to Anthony Hill.

Pigou noted the Medical Council had already written to Craig Climo several months earlier, expressing concerns about the "apparent interpersonal conflict" with the plastic surgery department and the possible negative impact on public safety.

"Based on concerns about several doctors at Waikato Hospital that have been brought to Council's attention, it appears that there may be some interpersonal and/or systemic issues in the Plastic Surgical unit at Waikato Hospital," Pigou wrote to Hill in August 2011.

"Because of this, Council has decided to refer the concerns to your office for your consideration."

Against this bitter backdrop, Hill later met with Craig Climo to discuss the Medical Council letter.

Notes written by Hill also show the Greenbaum's complaint about Walker's death was raised, revealing the Waikato DHB was no longer performing ILI.

Instead, they were sending patients to Sydney for the treatment. But the notes indicate most of the conversation was about Greenbaum.

"Most of what they discussed was character assassination," Greenbaum claims. "None of it stuck because none of it was true. But they were playing the man, not the ball."

For his part, Hill says the two complaints were assessed separately and followed proper process.

"It simply did not," Hill told the Weekend Herald, when asked whether the meeting had the effect of undermining Greenbaum.

"I strongly reject any inference of predetermined outcomes to cases."

More than a year after Walker's death, no "root cause" was identified when the Waikato DHB finally released its sentinel event investigation in September 2011.

However, the report confirmed "possible" issues with the tourniquet, which could have led to the undetected leaking of blood into the leg and out of Walker's body.

According to the report, while the DHB had protocols established for ILI, some were not best practice or linked together. There was no over-arching document, the report said.

Picture of Carmen Walker. Photo / Stuart Munro
Picture of Carmen Walker. Photo / Stuart Munro

And there were "potential delays" in decision-making and communication on the complicated procedure.

Finally, the "washout" waste fluid was not measured, which "possibly" led to delay in accurately assessing the blood loss.

After this, the Health and Disability Commission engaged an Australian surgeon as an independent expert witness.

In the opinion of Associate Professor Susan Neuhaus, the most likely cause of death for Walker was massive blood loss - or exsanguination.

"This occurred through drainage of a significant amount of her blood volume through the venous line into the effluent container," Neuhaus wrote in December 2011.

"This effluent volume was not monitored, or measured, and the team failed to recognise the extent of the problem until her cardiac arrest."

In other words, in Neuhaus' opinion, Walker was drained of blood as her leg was "washed out".

In response to Neuhaus, the surgeon who conducted Mrs Walker's procedure acknowledged his own report to the Coroner came to a similar conclusion.

However, at the time of writing, he was unaware of Walker was bleeding heavily in her ICU bed - as seen by Craig Walker - after her resuscitation.

He also re-investigated the volume of fluid in the waste bucket, as well as the maximum flow of liquid from the tube.

"I have reached the conclusion that it is impossible for the calculated blood loss to be accounted for through the venous drainage washout procedure," the surgeon wrote to the HDC.

"As such, I consider there must have been a second and significant blood volume loss to account for the observed changes."

Although the autopsy found no evidence of obvious haemorrhaging, he thought the source of the bleeding was more likely to be an undetected gastrointestinal bleed.

Such a severe bleed could have been caused by an angiodysplastic lesion, the pathologist who conducted the autopsy acknowledged, exacerbated by the blood thinner in her system.

This type of lesion was not found in Walker but is extremely difficult to detect even in autopsy.

So there were now two conflicting theories about what caused the fatal bleeding.

But there would have been no debate if the fluid in the waste bucket had been measured.

"It is readily apparent with hindsight that the weakness in our procedure was the inaccurate venous measuring system," the surgeon wrote.

"An accurate venous measuring system would have provided conclusive evidence whether the source of bleeding was a leak between systemic and leg circulation."

His explanation was sent back to Professor Neuhaus. She disagreed.

Craig and Linda Walker (son and daughter-in-law of Carmen Walker). Photo / Stuart Munro, Whanganui Chronicle
Craig and Linda Walker (son and daughter-in-law of Carmen Walker). Photo / Stuart Munro, Whanganui Chronicle

In her opinion, the bleeding of Walker in the ICU bed was most likely coagulopathy - a condition where the blood loses its ability to clot.

This can be the consequence - not the cause - of the massive blood loss which Neuhaus believed Walker suffered during the ILI procedure.

"I find the possibility of a gastrointestinal bleed during the procedure considerably less plausible," she wrote in May 2012.

Back-and-forth correspondence between Neuhaus and the HDC was exchanged on six occasions.

Each time, her opinion remained unchanged.

In her final letter in April 2013, Neuhaus maintained her position on the events leading to Walker's death were a "variance from normal" which she considered "severe".

"It would not be reasonable to construe these comments as relating to a view of [the surgeon's] conduct ... whilst responsibility for the entirety of Walker's care rests with the admitting surgeon, there were clearly other issues that impacted on the fatal outcome.

"I am of the opinion that, had adequate systems and monitoring been in place, the adverse events may have been identified earlier and the fatal outcome prevented."

Hundreds of pages of medical reports, analysis and opinion boiled down to one word.

Suboptimal.

When Anthony Hill released his draft report in November 2013, he concluded aspects of the care given to Carmen Walker were suboptimal.

Hill found fault with the Waikato DHB for having contradictory protocols and not having a dedicated team for ILI, which is a complex procedure.

He also pointed out it was the lead surgeon's responsibility to ensure the team was adequately briefed.

In particular, he was critical of the lack of measures to check tourniquet leakage and blood outflow.

"A procedure of this kind must have adequate systems in place to ensure the early detection of serious complications," Hill said.

"It is my view that where a vascular procedure involves the removal of a significant volume of blood from a patient, there should be systems in place to alert the surgical team."

Ironically, this failure meant Hill could not make a factual finding as to the cause of the massive bleeding.

Was it an unrecognised tourniquet leak during ILI, as his expert witness believed?

Or an undetected gastrointestinal bleed, as suggested by the plastic surgeon?

"The level of outflow fluid was not measured by [the surgeon]. This was not required by the Waikato DHB's ILI protocol. As a result, it is impossible to calculate the exact amount of blood drained from your wife during the ILI procedure," Hill wrote to Bob Walker.

"However, it is not my role to determine the cause of your wife's death. This is a matter for the Coroner."

The Coroner had already ruled on the cause of death - "cardiogenic shock" - without knowing the problems with Walker's care, or if they were a contributing factor.

Following Walker's death the Waikato DHB stopped performing ILI.

If this changed in the future, Hill said the DHB would make the necessary changes to make sure the procedure was safe.

As there was no further risk to public safety, the independent health watchdog decided to take no further action under under the discretionary powers available to him.

The Waikato DHB and the surgeon both sent letters of apology.

In a statement to the Weekend Herald, the DHB said it always intends to deliver the best possible care to patients.

"It is regrettable that on this occasion, eight years ago, we did not live up to our own expectations and we continue to express our apologies to the family. We engaged fully in the Health and Disability Commissioner's Investigation at that time and accept the associated findings."

And that was the end of the matter. All of which was little comfort to the Walkers.

Three years had passed since Carmen Walker's death, a stressful time for her husband and family as they waited for answers.

Around the time the HDC findings were released, Bob Walker suffered a stroke. He was placed in palliative care and died in February 2014.

"Mum's death had a huge effect on my father. He never recovered," Craig Walker says.

"He would always bring it up," Linda Walker says. "He died waiting for answers which never came, which is pretty sad."

Eight years after Walker died, the couple are speaking out now as they believe those questions are still unanswered.

There's been a Coroner's report, an internal audit and the Health and Disability Commissioner's findings.

"But no one has put the full picture together. No one has gotten to the bottom of it," Craig Walker says.

Even with so many unanswered questions, the Walkers say they would be even more in the dark if not for a doctor speaking up.

For them, Greenbaum - who's currently engaged in litigation with private hospitals in the Waikato -was vindicated, not vindictive, in laying the complaint.

Even now, the Walkers struggle to understand how there could be suboptimal care of someone who died but no further action taken.

"It's hard to believe someone could die in circumstances like this and nothing happens. It just feels like Mum's death was swept under the carpet."

The Carmen Walker case

March 2009:

Carmen Walker diagnosed with metastatic melonama on her right leg. Later referred to Waikato Hospital for isolated limb infusion (ILI).

August 2010: - Undergoes ILI but dies following the procedure. Autopsy report lists cause of death as "cardiogenic shock" (heart cannot pump enough blood to support body). Death triggers "sentinel event" investigation within DHB.

April 2011: Cause of death confirmed as cardiogenic shock by Coroner Gordon Matenga based on autopsy and report by lead surgeon.

May 2011: Dr Adam Greenbaum writes to DHB management with concerns he is not involved in the DHB investigation. Two weeks later lays complaint with the Health and Disability Commissioner Anthony Hill.

September 2011: DHB investigation concludes leaking tourniquet most likely cause of massive blood loss. However, identifies no root cause of death.

December 2011: Associate Professor Susan Neuhaus, the expert witness for the HDC, died from massive blood loss. In her opinion, this happened during the "washout" phase of the ILI where the volume of fluid was not measured.

April 2012: Surgeon writes to HDC and disagrees with opinion of Neuhaus as to cause of Walker's death. In his opinion, the level of blood loss could not have happened in "washout" phase and he believed an undetected gastrointestinal bleed was the source of the massive blood loss.

November 2012: HDC decies to formally investigate the complaint. Correspondence back-and-forth with Neuhaus for next 12 months. She stands by her original opinion.

November 2013: HDC finds there was "suboptimal" care and failings. Does not make factual finding on cause of death and takes no further action.