Abstract
Purpose
During spring 2009, a pandemic swine-origin influenza A (H1N1) virus (S-OIV) emerged and spread globally. We describe the chest X-ray and computed tomography (CT) findings of 40 patients with pneumonia due to S-OIV observed in our institution.
Material and methods
Among 534 patients with S-OIV, according to the US Centers for Disease Control and Prevention case definition, seen between June and November 2009, 121 underwent chest X-ray and 40 (median age 44 years, range 16–79) had pneumonia. The initial chest radiographs were evaluated for pattern, distribution and extent of lung abnormalities. Unenhanced chest CT scans were performed in two patients and were reviewed for the same findings. Underlying medical conditions were present in 42% of patients (17/40).
Results
Our patients had predominantly mild illness, and pneumonia was observed in 40 individuals (40/121 patients who had chest X-rays, 33%; and 40/534 patients with S-OIV, 7.5%). However, S-OIV can cause severe illness requiring admission to the intensive care unit for advanced mechanical ventilation and extracorporeal life support, including adult respiratory distress syndrome (ARDS) and death. The major radiological abnormalities observed were interstitial changes (60.0%), with (22.0%) or without patchy ground-glass appearance, mostly bilateral, and located in the lower lung zones (7.5%). Extensive disease was seen in 37.5% (15/40), and ARDS was observed in three individuals (0.30%)with underlying medical conditions. Subtle pleural effusion was noted in four patients.
Conclusions
In our series, the most frequent pneumonia patterns observed during S-OIV (H1N1) virus were interstitial changes and patchy ground-glass appearance, mostly bilateral, and located in the lower lung zones. CT, performed in severely ill patients, confirmed the ARDS identified with chest X-rays, better depicting the features and extent of lung abnormalities.
Keywords: Keywords S-OIV A (H1N1), Viral pneumonia, Chest radiograph, CT
Riassunto
Obiettivo
Scopo dello studio è quello di descrivere i quadri di presentazione radiologica della polmonite determinata dal virus influenzale A (H1N1), durante la pandemia sviluppatasi nella primavera del 2009.
Materiali e metodi
Nel periodo compreso tra giugno e novembre 2009 abbiamo identificato, mediante radiografia del torace, 40 polmoniti in pazienti con influenza A (H1N1), (età mediana 44 anni, range 16–79 anni). I radiogrammi relativi all’esame del torace effettuato al momento del ricovero e la tomografia computerizzata, eseguita in due casi, sono stati valutati relativamente al quadro di presentazione, alla distribuzione e all’estensione delle anormalità identificate. Il 42% dei pazienti (17/40) con polmonite presentava comorbilità.
Risultati
Nella nostra casistica, i pazienti hanno presentato prevalentemente un quadro clinico di media gravità e la polmonite ha complicato l’influenza in 40 di essi (40/121 [33%] pazienti con radiografia del torace e 40/534 [7,5%] pazienti con influenza A). In questi casi può rendersi necessario il ricovero presso reparti di rianimazione, poiché l’influenza può provocare complicazioni gravi fino alla acute respiratory distress syndrome (ARDS) e alla morte. Il quadro di presentazione radiologica più frequentemente osservato è stato l’impegno interstiziale (60%), con (22%) o senza consolidamenti multifocali a vetro smerigliato, bilaterali (70%) e localizzati nei campi polmonari inferiori (70%). Alterazioni parenchimali diffuse sono state identificate nel 37,5% dei casi (15/40) e la ARDS si è manifestata in tre pazienti (7,5%), tutti con comorbilità. Il versamento pleurico era presente in quattro casi.
Conclusioni
Il quadro di presentazione radiologica più frequente è stato l’impegno interstiziale, con o senza consolidamenti multifocali a vetro smerigliato, bilaterale e localizzato nei campi polmonari inferiori. La tomografia computerizzata, effettuata nei pazienti in condizioni cliniche gravi, ha confermato la ARDS, già identificata mediante la radiografia del torace, definendone meglio l’estensione e le caratteristiche semeiologiche.
Parole chiave: Influenza A (H1N1), Polmoniti virali, Radiografia del torace, TC
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