SINGAPORE: An elderly woman was accidentally given 10 times her prescribed dose of anaesthetic when undergoing treatment for a range of ailments at the Singapore General Hospital (SGH) two years ago, a coroner's inquiry revealed on Wednesday (Dec 19).
Madam Chow Fong Heng was pronounced dead two days later in an SGH ward, but a forensic pathologist certified the cause of her death as multi-organ failure and blood poisoning, with end-stage renal failure as a contributing factor.
AdvertisementSevere overdoses of the anaesthetic called lignocaine can result in seizures, morbidity and mortality, a medical officer from SGH's National Heart Centre testified.
Madam Chow did not show any signs of seizures expected from a lignocaine overdose.
Dr Ong Hui Shan, who had reviewed Madam Chow's condition on May 31 after the medical error was discovered, found that Madam Chow's mental state had deteriorated.
However, she told the inquiry that she could not attribute lignocaine toxicity with any role in Madam Chow's death, as Madam Chow "had suffered from life-threatening conditions which included sepsis, renal failure and ischaemic heart disease".
AdvertisementAdvertisementLIGNOCAINE CAUSE UNLIKELY, BUT INCIDENT STILL A CONCERN: CORONER
An SGH staff nurse who configured the pump that was to administer the medication to the patient over a period of time had accidentally keyed in a figure of 41.7ml/hr instead of 4.17ml/hr, said coroner Marvin Bay as he delivered his findings on Madam Chow's death.
Madam Chow was in May 2016 prescribed 1g of intravenous lignocaine - used to numb tissue and treat fast heart rate - over 24 hours. However, it was infused over 2.4 hours instead, the coroner said.
The staff nurse who keyed in the wrong figures was not identified in court documents. She said that she could either key in the dose selection or rate selection in the IV smart pump that was used to inject lignocaine into Madam Chow.
For the calculations to be correct, she should have keyed in 41.7mg per hour using dose selection or 4.17ml per hour using rate selection.
However, she accidentally keyed in 41.7ml in the rate selection instead, she said, adding that she was unfamiliar with the smart pump due to her limited exposure to it.
The staff nurse said that she attended to another patient after keying in the figure and continued with her routine duties afterwards, conceding that she did not check with a colleague if the settings had been correctly entered.
In his conclusion, the coroner said that two reports from experts with the Academy of Medicine Singapore had indicated lignocaine as unlikely to be a defining factor in Madam Chow's death.
Even so, the coroner said there were valid areas of concern in this case.
The staff nurse indicated "that she had no experience and limited exposure to the pump machine, but was nevertheless allowed to operate it", he said.
"She had of course made the gross error in calculations with regard to the amount of lignocaine administered, apparently confusing the application of units of milligram and millilitre and mistaken the dose selection for the rate selection in calculations of the concentration of the drug, in giving Madam Chow a dose which was effectively 10 times the prescribed dose," said the coroner.
He noted that SGH has acknowledged its shortcomings, taking steps to reinforce the importance of counter-checking where medications and sedatives are administered.
It has also ensured that nurses have "the requisite competency and knowledge when tasked to administer medications to patients", he added.
Channel NewsAsia has contacted SGH for more information.
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