A young male patient has been admitted with severe COVID-19 infection. He is maintaining oxygen saturaion with 4 litres of oxygen.
He was admitted in January 2021 for severe COVID-19 infection and remained on BIPAP.
He was alright until a few days back when he got re-infection.
His blood gases are suggestive of type 2 respiratory failure ( pCO2 of 80 mmHg) with a mild degree of hypoxemia.
He is not a smoker and chest examination only reveals fine crepitations at the bases.
What could be the cause of severe hypercapnea in this patient?
since patient previously suffered from severe Covid 19 infection and he remained on bipap now presented with reinfection with type 2 failure this presentation may be due to
* lung fibrosis secondary to ARDS
* Restrictive lung disease
*Pulmonary embolism
secondly look at status of heart to rule out right to left shunt or Pulmonart arterial hypeetension or angina
Arteriovenous shunting should be looked at in this case, since hypercapnea is disproportionate to the degree of hypoxemia.
What tests can we do do diagnose Arteriovenous shunting in this patient?
Transthoracic contrast echocardiography TTCE ( bubble study)
when microbubbles appear in LA
within one cardiac cycle of there appearance in RA :: intra cardiac shunt
within 3-8 cycles :: intrapulmonary shunt
within 01-03 cardiac cycles :: location of shunt is indeterminate
100%oxygenation :: to calculate shunt fraction and >5% is abnormal
CT chest contrast enhanced
Three dimensional contrast emhanced MR angiography
Pulmonary angiogram:; if Pulmonary AVM seen on CT