Surgical Masks as Effective as N95 Respirators for Preventing Influenza
Clinical question: How effective are surgical masks compared with N95 respirators in protecting healthcare workers against influenza?
Background: Evidence surrounding the effectiveness of the surgical mask compared with the N95 respirator for protecting healthcare workers against influenza is sparse.
Study design: Randomized, controlled trial.
Setting: Eight hospitals in Ontario.
Synopsis: The study looked at 446 nurses working in EDs, medical units, and pediatric units randomized to use either a fit-tested N95 respirator or a surgical mask when caring for patients with febrile respiratory illness during the 2008-2009 flu season. The primary outcome measured was laboratory-confirmed influenza. Only a minority of the study participants (30% in the surgical mask group; 28% in the respirator group) received the influenza vaccine during the study year.
Influenza infection occurred with similar incidence in both the surgical-mask and N95 respirator groups (23.6% vs. 22.9%). A two-week audit period demonstrated solid adherence to the assigned respiratory protection device in both groups (11 out of 11 nurses were compliant in the surgical-mask group; six out of seven nurses were compliant in the respirator group).
The major limitation of this study is that it cannot be extrapolated to other settings where there is a high risk for aerosolization, such as intubation or bronchoscopy, where N95 respirators may be more effective than surgical masks.
Bottom line: Surgical masks are as effective as fit-tested N95 respirators in protecting healthcare workers against influenza in most settings.
Citation: Loeb M, Dafoe N, Mahony J, et al. Surgical mask vs. N95 respirator for preventing influenza among health care workers: a randomized trial. JAMA. 2009;302 (17):1865-1871.
Neither Major Illness Nor Noncardiac Surgery Associated with Long-Term Cognitive Decline in Older Patients
Clinical question: Is there a measurable and lasting cognitive decline in older adults following noncardiac surgery or major illness?
Background: Despite limited evidence, there is some concern that elderly patients are susceptible to significant, long-term deterioration in mental function following surgery or a major illness. Prior studies often have been limited by lack of information about the trajectory of surgical patients’ cognitive status before surgery and lack of relevant control groups.
Study design: Retrospective, cohort study.
Setting: Single outpatient research center.
Synopsis: The Alzheimer’s Disease Research Center (ADRC) at the University of Washington in St. Louis continually enrolls research subjects without regard to their baseline cognitive function and provides annual assessment of cognitive functioning.
From the ADRC database, 575 eligible research participants were identified. Of these, 361 had very mild or mild dementia at enrollment, and 214 had no dementia. Participants were then categorized into three groups: those who had undergone noncardiac surgery (N=180); those who had been admitted to the hospital with a major illness (N=119); and those who had experienced neither surgery nor major illness (N=276).
Cognitive trajectory did not differ between the three groups, although participants with baseline dementia declined more rapidly than participants without dementia. Although 23% of patients without dementia developed detectable evidence of dementia during the study period, this outcome was not more common following surgery or major illness.
As participants were assessed annually, this study does not address the issue of post-operative delirium or early cognitive impairment following surgery.
Bottom line: There is no evidence for a long-term effect on cognitive function independently attributable to noncardiac surgery or major illness.
Citation: Avidan MS, Searleman AC, Storandt M, et al. Long-term cognitive decline in older subjects was not attributable to noncardiac surgery or major illness. Anesthesiology. 2009;111(5):964-970.