“Drink plenty of fluids”

Editor—Guppy et al, the authors of the recent article “ 'Drink plenty of fluids': a systematic review of evidence for this recommendation in acute respiratory infections,” may have left readers with recommendations and implications that are not supported by the data they have reviewed.¹

Figure 1.

Credit: CHARLES GULLUNG/PHOTONICA

Infections of the upper respiratory tract and episodes of bronchitis are very common and presumably outnumber episodes of pneumonia by a factor of more than 100. The only data they give to show that excess fluid is potentially harmful in acute respiratory infections is from studies with moderate to severe pneumonia. Although Guppy et al give a number of theoretical reasons for why antidiuretic hormone may be increased in respiratory infections, most of those mechanisms would not be relevant in conditions where pneumonia was not present. Their article would have been better entitled “ 'Drink plenty of fluids': a systematic review of evidence for this recommendation in moderate to severe pneumonia.”

The title of their article has implications for all respiratory infections, including those of the upper respiratory tract. I, however, do not believe the data they have reviewed should be used to extrapolate for conditions other than moderate to severe pneumonia (and with these latter cases one would hope close medical or hospital supervision was taking place and so hyponatraemia could be avoided). We need to ensure that we do not leave the community with the implication that this advice applies to the much more common infections of the upper respiratory tract.

As Guppy et al say in the first paragraph of their paper, it seems self evident that there are many benefits in keeping patients with less serious respiratory tract infections well hydrated. They have presented no data to show that this “common sense” approach should not continue to be the case.