Doctors at an intensive care unit were baffled when a 40-year-old man did not survive even after he was put on a ventilator. The patient had a good health without a history of any comorbidity before contracting the novel coronavirus.
He was admitted to the Kurmitola General Hospital in the capital after he had shown coronavirus-like symptoms including fever, cough, and mild respiratory distress.
His condition worsened fast prompting his transfer from a ward to the intensive care unit (ICU). His pulse oxygen saturation level, which indicates how much oxygen is flowing to the organs, fell alarmingly below 90 percent. The range between 95 and 100 percent is considered safe.
The ventilator was whirled to its full capacity in vain. The patient died four days later. His death nearly one and a half months ago and many other Covid-19 cases afterwards led to the unraveling of the mystery as to why oxygen was not entering other organs from the lungs supplied with oxygen by the ventilator.
"Several medical investigations indicated that blood clots had developed in the lungs, which might create an obstruction to the oxygen flow," said Dr Md Harun Ur Rashid, who is at present working as the registrar of the ICU at the Kurmitola Hospital.
And it is not only the lungs where blood clots develop because of the novel coronavirus. "It can happen in the brain causing a stroke, in the heart resulting in a heart attack and in the kidneys causing them to fail," said Robed Amin, a doctor at the medicine department in the Dhaka Medical College Hospital (DMCH).
Sometimes the consequence of blood clots is a gradual process, and sometimes it is sudden to catch healthcare providers off guard. Whatever is the case, the formation of blood clots raises the chance of fatality.
There were a handful of instances at the DMCH when patients died before doctors could move them to the ICU from an isolation ward.
Dr Mostafa Aziz Sumon at the Kurmitola Hospital recounted such an incident of unexpected death of an imam [religious cleric] from Narayanganj.
"He sat up on his bed and when he lay back, he was dead. We, doctors, could not fathom out the reasons behind this sudden death," said Dr Sumon.
It is suspected that pulmonary thrombo-embolism, which means a blockage in the pulmonary vessels by blood clots, is one of the causes of such unexplained deaths.
"A post-mortem analysis could substantiate this hypothesis, but this is quite challenging, given the lack of resources and the socio-cultural background," Dr Sumon added.
Up to 30 percent European patients seriously ill with Covid-19 develop dangerous blood clots, reported the BBC. But no study has been carried out yet in Bangladesh to find out how many hospitalised patients here are showing such symptoms.
Dr Amin said the DMCH has recently initiated a process to collect data of such patients.
How the body's immune system fights the virus
Blood clot in the lungs or somewhere else in the body is a manifestation of the immune system's aggressive reaction to the virus.
When the body is affected by the virus, the immune system causes inflammation. If the inflammation goes uncontrolled, it is called cytokine storm. At the same time, the coagulation system gets overactive, resulting in blood clots in different parts of the body.
"In a small-scale study on Covid-19 patients in ICU, doctors observed that about 36 percent of them suffer from an overriding immune system," said Dr Harun.
"In some instances, the body's fight against the virus causes damages to different tissues, which may result in multi-organ failure in the worst-possible scenario," he added.
With the increasing cases of infection and fatalities, doctors have devised treatment protocols that showed promising results.
"As a patient's fever remains high for days, coupled with an oxygen saturation level of 93-94 percent, doctors prescribe anticoagulant injections as a preventive measure against blood clots and steroid to subdue the cytokine storm," Dr Harun said.
Dr Sumon said that over the last one month, blood parameters of serious patients are being checked to rule out the possibility of coagulation.
However, since the hospitals are increasingly being overcrowded, many patients with mild to moderate symptoms are advised to stay in home isolation.
Dr Harun suggested that a patient at home should be in touch with doctors so that he could be advised to take oral anticoagulant drugs and other medicines, when necessary.
"This may keep many patients from coming to hospitals for admission. The preventive drugs may also keep many patients from being shifted to the ICU. I consulted many patients over the phone and they are doing better," he argued.