While a prone position may ease breathing in severely ill Covid-19 patients on ventilators, scientists say this life-saving, face-down posture can also cause permanent nerve damage in these vulnerable individuals.
According to the researchers, including those from Northwestern University Feinberg School of Medicine in the US, the nerve damage is a result of reduced blood flow and inflammation, which other non-Covid-19 patients on ventilators in this position rarely experience.
Based on the study, accepted for publication in the British Journal of Anaesthesia, the scientists said this type of injury has been missed because critically ill people are expected to wake up with some generalised weakness when they have been bedridden.
But the researchers said this pattern of weakness in the Covid-19 patients during rehabilitation is quite often in an important joint such as the wrist, ankle, or shoulder, and these body parts would be completely paralysed on one side of the body.
"It's shocking how big a problem it is. This is a much higher percentage of patients with nerve damage than we've ever seen in any other critically ill population," said study co-author Colin Franz from the Northwestern's Feinberg School of Medicine.
"Ordinarily, very sick people can tolerate the position that helps their breathing. But Covid-19 patients' nerves can't tolerate the forces other people can generally bear," Franz said.
According to scientists, 12 to 15 per cent of the most severely ill Covid-19 patients have permanent nerve damage, which Franz estimated may tally to thousands of patients across the world.
"It's underappreciated if you take our numbers and extrapolate them," Franz said.
"We noticed patients are getting a lot of pressure at the elbow or at the neck, so we've made some adjustments to the way we position the joints as well as putting extra padding under the elbow and the knee where there is the most pressure," he added.
The researchers noted that the most common injuries are wrist drops, foot drops, loss of hand function, and frozen shoulder, while some patients had as many as four distinct nerve injury sites.
Citing previous studies, the scientists said therapeutic neural stimulation may work to help regrow nerves.
But they added that many patients have pre-existing conditions that interfere with nerve regeneration, such as diabetes mellitus, making it less likely for them to recover full function.
"This could mean permanent difficulties with walking or critical hand functions like writing or operating a computer or cell phone," Franz said.
The researchers said they are currently working on a pressure map of hot spots for nerve sensitivity, radiology imaging to document the injury and skin sensors to help identify better "prone" position strategies.
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