Some Uncommon Facts About the Common Cold
Synopsis: Paranasal sinus involvement in the common cold may be explained by the finding that nose blowing is associated with the passage of nasal secretions into the paranasal sinuses.
Source: Gwaltney JM Jr, et al. Clin Infect Dis 2000;30:387-391.
The common cold is frequently associated with symptoms suggestive of the presence of paranasal sinusitis and evidence indicates that fluid may frequently be present in the sinuses of patients with colds. Gwaltney and colleagues set out to determine a potential mechanism for this finding.
Intranasal pressures were measured in healthy adult volunteers during nose blowing, sneezing, and coughing, and paranasal sinus CTs were performed after each of these maneuvers with instillation of radiopaque contrast medium into the nasopharynx. While mean intranasal pressure transiently increased to only 6.6 mm Hg and 4.6 mm Hg after, respectively, coughing and sneezing, it increased to 66.2 mm Hg after nose blowing. The mean pressure during quiet respiration was only 0.9 mm Hg. Sneezing with the mouth closed was associated with peak intranasal pressures of 88-76 mm Hg.
Mathematical modeling indicated that only trivial amounts of nasal fluid would flow into the maxillary sinus after sneezing or coughing. In contrast, 1 mL flowed into this cavity after nose blowing. Consistent with this prediction, CT scans demonstrated contrast intrusion into the osteomeatal complex and ethmoid and sphenoid sinuses of all four volunteers and in the maxillary and frontal sinuses of two of the four. Air bubbles were seen in the maxillary and sphenoid sinuses of one of the volunteers.
Comment by Stan Deresinski, MD, FACP
This same investigative group has previously demonstrated that the overwhelming majority of patients with symptoms of the common cold have CT evidence of paranasal sinus abnormalities.1 The proposed means by which these abnormalities occur have included direct viral infection of the sinus mucosa and secondary bacterial infection. The observations described above provide another, more direct mechanism—the propulsion of nasal secretions into the sinuses as a result of nose blowing, something that occurs an average of 45 times during the first three days of an experimental cold.2 This phenomenon had previously been suggested to Gwaltney et al by the detection of air bubbles in the sinuses of patients with colds.
One potential consequence of this hydrodynamic effect is secondary bacterial infection of the paranasal sinuses, a complication said to occur in approximately 2% of common colds.3 Making a clinical distinction between the patient with bacterial sinusitis from that with uncomplicated but symptomatic nonbacterial sinusitis ("viral sinusitis") is difficult. No single finding is diagnostic. A biphasic illness may occur and the presence of several of the following is suggestive: maxillary toothache, poor response to decongestants, history or observation of colored or purulent nasal discharge, and abnormal transillumination.4,5
The treatment of the uncomplicated common cold has been the subject of a series of meta-analyses by the Cochrane group. Their conclusions include the following:
• A single dose of nasal decongestant is associated with a mean 13% decrease in subjective symptoms relative to placebo.6 No evidence supports their repeated use over several days.
• The use of heated, humidified air is associated with subjective, but not objective improvement.7
• The benefit of zinc lozenges is uncertain.8
• Vitamin C does not prevent the common cold, but high doses may have a modest (8-9%) reduction in duration of symptoms.9
• The role of Echinacea preparations is unclear.10
• Antibiotic therapy was associated with increased incidence of adverse events, but no improvement in symptoms.11
Unfortunately, the question of antibiotic therapy remains a complicated one. A recent study attempted to determine if the putative anti-inflammatory effects of macrolide antibiotics might improve the symptoms of the common cold, independently of their antimicrobial effects.l In this study, patients were randomized to receive either clarithromycin or trimethoprim-sulfamethoxazole; there was no difference in outcomes.12 Unfortunately, no placebo group was included.
A subset of patients may, however, benefit from antibiotic therapy. Kaiser and colleagues randomized patients to receive either co-amoxiclav or placebo. While no improvement was associated with antibiotic therapy in the entire group of patients, in the subset (approximately 20%) whose entry cultures yielded either S. pneumoniae, M. catarrhalis, or H. influenzae, co-amoxiclav administration was associated with significantly less severe and prolonged illness. Unfortunately, this subset could not be identified by clinical criteria.13 Thus, the findings have no current practical significance since waiting for culture results would likely obviate the benefit in the subset with evidence of bacterial respiratory pathogens. Withholding antibiotics is often difficult and time-consuming for the clinician, given the fact that 44% of adults believed that antibiotic therapy is effective in the treatment of the common cold.14
Another intervention that has been evaluated is the use of nasal corticosteroids. Unfortunately, the use of intranasal fluticasone propionate did not improve the symptoms of the common cold and its use was associated with increased viral shedding, a finding also reported with aspirin administration.15,16
On the other hand, two other interventions have each been demonstrated to reduce nasal secretions: oral administration of antihistamines (brompheniramine, clemastine fumarate) and the intranasal administration of ipatropium bromide.2,17,18 The reduction of rhinorrhea may potentially decrease the amount of fluid expelled into the paranasal sinuses during nose blowing and thereby diminish the risk of bacterial sinusitis. (Dr. Deresinski is Clinical Professor of Medicine, Stanford University, Director, AIDS Community Research Consortium, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, Redwood City, Calif.)
References
1. Gwaltney JM Jr, et al. N Engl J Med 1994;330:25-30.
2. Gwaltney JM Jr, Druce HM. Clin Infect Dis 1997;25: 1188-1194.
3. Gwaltney JM Jr. Can Respir J 1999;Suppl A:46A-50A.
4. Low DE, et al. CMAJ 1999;156(Suppl 6):S1-S4.
5. Williams JW Jr, et al. Ann Intern Med 1992;117:705-710.
6. Taverner D, Bickford L, Draper M. Cochrane Database Syst Rev 2000;2:CD001953.
7. Singh M. Cochrane Database Syst Rev 2000;2: CD001728.
8. Marshall I. Cochrane Database Syst Rev 2000;2: CD001364.
9. Douglas RM, et al. Cochrane Database Syst Rev 2000;2:CD000980.
10. Melchart D, et al. Cochrane Database Syst Rev 2000; 2:CD000530.
11. Arroll B, Kenealy T. Cochrane Database Syst Rev 2000;2:CD000247.
12. Abisheganaden JA, et al. Am J Med 2000;108:453-459.
13. Kaiser L, et al. Lancet 1996;347:1507-1510.
14. Braun BL, et al. J Fam Pract 2000;49:153-156.
15. Puhakka T, et al. J Allergy Clin Immunol 1998;101: 726-731.
16. Graham NM, et al. J Infect Dis 1990;162:1277-1282.
17. Diamond L, et al. J Allergy Clin Immunol 1995;95: 1139-1146.
18. Gwaltney JM Jr, Druce JM. Antimicrob Agents Chemother 1999;43:822-829.
19. Gwaltney JM Jr, et al. Clin Infect Dis 1996;22:656-662.
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