Viral pneumonias which might lead to respiratory distress are mainly influenza, adenovirus, and varicella and cytomegalovirus infections. Most of the viral pneumonias admitted to the ICU only require symptomatic treatment. However, antiviral drugs are useful in some situations.
Amantadine hydrochloride has been shown to be useful for prophylaxis against influenza A infection. Anecdotal cases of improvement, when given early in the course of the disease, have been reported.
Intravenous acyclovir (aciclovir) has been used early in the onset of severe varicella zoster virus pneumonia and seems to reduce the respiratory rate and the duration of fever, and to improve oxygenation. It probably favors the healing of bronchial lesions.
The same treatment might be recommended for the rare cases of severe necrotizing herpes simplex virus pneumonia, although there are no published data, as acyclovir is highly active in vitro and is non-toxic. The dose for severe pneumonia due to varicella zoster virus is 500 mg/m2 intravenously every 8 h for 5 to 10 days.
Ribavirin (tribavarin, Virazole) given in aerosolized form has been associated with a more rapid improvement of blood gases and decrease of viral shedding in respiratory syncytial virus bronchiolitis and pneumonia in children. Aerosol ribavirin has been used in influenza B infection in young adults in a placebo control trial and resulted in a more rapid defervescence, decrease in viral shedding, and improvement in clinical symptoms. Thus this agent might be useful in the treatment of severe influenza and respiratory syncytial virus pneumonia. The suggested dose is 6 g in 300 ml of water by continuous nebulization 18 to 24 h daily for 3 to 7 days. This difficult method of administration requires a closed system to prevent exposure of hospital personnel and this limits its usefulness.
Ganciclovir is used against cytomegalovirus and is effective in decreasing viral shedding from the lung of immunocompromised patients with pneumonia. However, mortality remains high under treatment, and some patients remain alive and well without treatment.
As was pointed out earlier, severe viral pneumonias require mainly symptomatic treatment and adequate ventilation with end-expiratory pressure if necessary. It must be remembered that bacterial superinfection with Staphylococcus aureus, Staphylococcus pneumoniae, or Hemophilus influenzae accompanying viral pneumonia is frequent, particularly with influenza pneumonia, and must be appropriately treated.
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