Surgeon burned his note of medical procedure that killed patient

As Carmen Walker’s hospital procedure came to a close, two things happened: tourniquets isolating her leg where concentrated chemotherapy had been perfused and washed out were lifted, and she was injected with the “dirty drug” protamine.

Shortly after, the 78-year-old Whanganui woman “crashed” on the operating table as her blood pressure collapsed and she went into cardiac arrest. Walker died later that night in the intensive care unit.

The cause of her unexpected collapse is being examined by Coroner Alexander Ho in an inquest at Hamilton District Court, 13 years after Walker underwent an isolated limb infusion at Waikato Hospital to treat a melanoma spreading from her right ankle.

The focus has been on whether Walker died of hypovolaemia caused by massive blood loss through a leaking tourniquet, or internal bleeding, or through catastrophic fluid loss and low blood pressure caused by anaphylaxis to protamine.

Emergency on-call anaesthetist Dr Arthur Rudman told the inquest on Thursday protamine was referred to as a “dirty drug” because it was so highly anaphylactic, with one in 10 people reacting to it.

Protamine was a necessary part of the end of anaesthesia because it reversed the effects of the anticoagulant heparin, which is given before surgery to prevent blood clotting.

The anaesthetist in charge of Walker’s care on August 3, 2010, told the inquest when the patient’s blood pressure dropped after the second tourniquet was released, he immediately suspected anaphylaxis from the 30ml of protamine he’d just injected.

As Walker went into arrest, the anaesthetist, who has name suppression, urgently called for Rudman to conduct a trans-oesophageal echocardiogram (TOE) that showed the left ventricle of her heart was “very empty”.

The anaesthetist pivoted to a differential diagnosis of hypovolaemia caused by significant blood loss and ordered two units of red blood cells and other blood products.

Today, the surgeon in charge of the procedure began his testimony, telling the inquest he burned his own detailed note of the medical event in a bonfire with other documents he had in storage about five years ago.

However, he admitted the note he’d made within 24 hours of the procedure was the basis of his report to the first coroner’s inquiry in early 2011.

The surgeon, who also has name suppression, told the inquest he initially thought it was likely Walker’s death was caused by blood loss through leaking tourniquets.

A significant leak would have meant the blood from the rest of Walker’s body had seeped into her leg during the procedure and would have been drained out of her during exsanguination of the leg to remove the chemotherapy drug melphalan.

In that scenario, when the tourniquets were lifted, the heart suddenly did not have enough blood to pump around the body.

The inquest has heard other potential causes of her cardiac arrest included cardiotoxicity caused by the melphalan, a gastrointestinal (GI) tract bleed or internal bleeding from catheters inserted in her groin to perfuse the melphalan, anaphylaxis, or age.

The surgeon confirmed an observing surgeon’s earlier testimony that there was only one bucket of blood, fluid, and waste in the procedure, and he wasn’t initially concerned with the amount of fluid in it.

But later, at the insistence of observer Dr Adam Greenbaum, they took another look in the bucket and he thought it looked fuller than normal.

Asked by lawyer for the Coroner, Chris Gudsell, KC, why he didn’t simply tip the fluid out and measure it, the surgeon said he was comfortable with the amount in the bucket.

Under questioning by lawyer for the family Phillip Cornege, the surgeon admitted it would have been possible to drain the fluid and measure it.

He said there was no hospital policy for the procedure to measure the output fluid, and measuring would have been his responsibility.

When asked about whether he could have checked for tourniquet leaks using a hand-held Doppler or other radiology devices, the surgeon said he could have but didn’t as he was satisfied that because there was no pulse in the leg there was no leak.

Cornege also put to the surgeon that he wasn’t properly trained to undertake the isolated limb infusion, which he conceded, though he had performed about 18 of them at Waikato Hospital over a number of years.

The surgeon initially told Coroner Gordon Matenga in 2011 he thought hypovolaemia was the most likely cause of death but told a Health and Disability Commissioner’s (HDC) investigation in 2013 he believed Walker’s blood loss was from an internal lesion.

Earlier the inquest heard from specialist anaesthetist Dr John Torrance, in charge of Walker when she was admitted to intensive care, that it would have required a number of treatments to keep the pensioner alive.

Torrance said Walker’s family was told that because of the prolonged 90-minute resuscitation it was likely she had suffered severe brain damage.

He believed Walker’s melanoma was advanced and saving her life so she could soon die of the cancer was “cruel”, though Cornege noted Walker was not expected to die imminently from melanoma.

There was also suspicion of GI tract bleeding because of blood released from the rectum, indication of a dying bowel.

However, Cornege pointed to the fact Walker was still affected by the heparin and that because her blood couldn’t clot, she was slowly bleeding to death through various outlets.

He asked why Torrance did not give Walker protamine to reverse the anticoagulant to allow time to assess her neurological damage but Torrance said there was a high chance the protamine might have been the cause of the cardiac arrest and if administered again she would likely die.

The inquest heard the intensive care unit (ICU) did not actively treat Walker, instead making her comfortable and giving her family time to say goodbye. Her care that night was left to a first-year registrar.

Walker’s discharge summary from ICU recorded her “terminal” life-ending event as massive rectal bleeding.

Natalie Akoorie is the Open Justice deputy editor, based in Waikato and covering crime and justice nationally. Natalie first joined the Herald in 2011 and has been a journalist in New Zealand and overseas for 27 years recently covering health, social issues, local government, and the regions.