Severe Cases of H1N1 at Risk for Pulmonary Emboli

[indigo girl]

http://www2.med.umich.edu/prmc/media/newsroom/details.cfm?ID=1338

...The majority of patients with H1N1 that undergo chest X-rays have normal radiographs. CT scans proved valuable in identifying those patients at risk of developing more serious complications as a possible result of the H1N1 virus," says Agarwal.

The research included 66 patients diagnosed with the H1N1 flu. Of those, 14 were patients that were severely ill and required Intensive Care Unit admission.

...Pulmonary emboli were seen in CT scans on five of the 14 ICU patients.

Another important finding is that initial chest radiographs were normal in more than half of the patients with H1N1, says Kazerooni.

"These findings indicate that imaging studies would have to be repeated in severely ill patients to monitor disease progression," said Kazerooni. "It's important to heighten awareness not only among the radiologists, but also among the referring clinicians."

[lamazeteacher]

Pulmonary emboli occur in patients in ICUs with some frequency, as their inhibited ability to move can cause DVTs, which in turn land in the lungs with lethal results. Baseline scans for emboli need to be done upon or just before admission to ICU (gets the staff there off the hook, if emboli exist then); and involuntary moving of extremities needs to be given more emphasis in ICU.

I don't see cause to think the emboli result just from H1N1, unless autopsies indicate a plethara of that in deaths that occur outside the ICU.

[indigo girl]

Pulmonary emboli occur in patients in ICUs with some frequency, as their inhibited ability to move can cause DVTs, which in turn land in the lungs with lethal results. Baseline scans for emboli need to be done upon or just before admission to ICU (gets the staff there off the hook, if emboli exist then); and involuntary moving of extremities needs to be given more emphasis in ICU.

I don't see cause to think the emboli result just from H1N1, unless autopsies indicate a plethara of that in deaths that occur outside the ICU.

That was my thought also but this is not what they seem to be saying. They appear to be saying that the influenza is producing a hypercoagulable state. What is different is that this is not seen in seasonal flu cases. Maybe we should send a query to the authors and ask more about this. I think that this is significant to this particular virus.

http://www.medwire-news.md/62/84822/Thrombosis/PE_risk_highlighted_in_severely_ill_swine_flu_patients.html

Overall, 42% of patients had abnormalities in their initial chest radiograph. The most common finding was patchy consolidation (50%), usually in the lower (71%) and central (71%) lung zones.

All ICU patients had abnormal initial radiographs and 13 (93%) had extensive disease, defined as affecting three or more lung zones, compared with just 9.6% of non-ICU patients. Furthermore, 13 (93%) of ICU patients had more than 20% of their lungs affected compared with none of the non-ICU patients.

Chest CT was performed in 10 ICU and five non-ICU patients using intravenous contrast. PE was diagnosed in five (36%) of the ICU group. One patient developed a saddle embolus at the bifurcation of the main pulmonary artery, and another had lobular emboli, while two were diagnosed with segmental and one with subsegmental PE. A further two patients were diagnosed with deep vein thrombosis.

“Although sepsis and acute respiratory distress syndrome are known to represent hypercoagulable states, acute PE is not a common complication of influenza infection,” Agarwal et al observe.

Nevertheless, they write: “Knowledge of this complication, which presumably is secondary to a hypercoagulable state in these patients, is important not only for the clinicians taking care of the patient but also for the radiologist so as to avoid missing emboli on contrast-enhanced CTs performed for other reasons."