Intrathecal injection warrants mask worn by clinician during procedure

From the June 18, 2009 issue

Last month, two women who had just given birth to healthy babies developed bacterial meningitis following intrathecal injections of anesthesia by the same anesthesiologist.1One of themothers, who was only 30 years old, died within days of acquiring the infection, while the other mother is still recovering. Cultures identified Streptococcus salivarius, a common organism found in the mouth and respiratory tract, as the bacteria that caused themeningitis
in both women.
The department of health in Ohio, where this incident occurred, investigated the adverse events, collecting patient, drug, and equipment samples and reviewing the practices associated with the delivery of spinal or epidural anesthesia during labor. According to a news report,1 the health department identified infection control problems as well as inadequate patientmonitoring post spinal anesthesia as contributory to the events. In particular, the health department determined that the eventsmay have been linked to the anesthesiologist’s failure to wear a mask during the administration of spinal medications. The health department’s inspectors also found outdated medications in the labor and delivery area but did not conclude they were linked to the outbreak, as the microorganism implicated in the events is common in nasal and oropharyngeal flora.
According to the medical director at the hospital where the events happened,1 anesthesiology teams did not routinely wear surgical masks during spinal/epidural procedures—although they do now. Wearing a mask during these procedures may seem a reasonable precaution, even though bacterial meningitis or infections such as epidural abscesses are rare sequelae of spinal anesthesia.2,3 Yet, the issue has been widely debated, and literature on this topic can be found in support of both wearing and not wearing a mask.
Proponents of wearing a mask cite common sense and well-established evidence proving the effectiveness of universal precautions (to protect worker and patient) as adequate to convince anesthesiologists to wear a mask during administration of spinal/epidural anesthesia. However, if more evidence is needed, proponents point to multiple studies that link bacterial meningitis and epidural abscesses to Streptococcus pathogens cultured from the nose or throat of clinical staff, including anesthesiologists.4-12 Moreover, laboratory evidence corroborates the clinical value of surgical masks in preventing the transmission of organisms from the upper airway and limiting bacterial contamination of a surface.13-15
Opponents of wearing a mask during spinal/epidural anesthesia suggest there are more case reports and studies in the literature that describe the occurrence of bacterial meningitis and epidural abscesses despite the anesthesiologist wearing a face mask than there are implicating the anesthesiologist when no mask was worn.16-18 They acknowledge that case reports often implicate nose and throat flora of the anesthesiologist, but suggest that the studies do not prove the anesthesiologist (or other clinician) actually caused the infection. Some studies of iatrogenic bacterial meningitis and epidural abscesses also fail to mention whether amaskwasworn or not during the procedure, making it difficult to draw accurate conclusions on the subject.While one well-cited study showed that face masks decreased growth in agar plates placed 30 cm in front of anesthesiologists who talked for several minutes, the same study showed increased bacterial growth once the masks had been worn for 15 minutes when compared to wearing no mask at all.13 Since anesthesiologists rarely change their masks during a procedure (and may use the same mask for the entire day), the mask may increase the risk of transmitting a bacterial infection. The need to wear a mask during a spinal/epidural procedure is also questioned on the basis of evidence that masks do not actually decrease the rate of surgical wound infections.3
In 2004, the Centers for Disease Control and Prevention (CDC) investigated eight cases of post-myelography meningitis that were reported or identified through a survey.19 Blood and/or cerebrospinal fluid of all eight cases yielded Streptococcal species consistent with nasal and oropharyngeal flora, and there were changes in the cerebrospinal fluid indices and clinical status indicative of bacterial meningitis. Equipment and products used during these procedures (e.g., contrast media) were excluded as probable sources of contamination. Procedural details available for seven cases determined that antiseptic skin preparations and sterile gloves had been used. However, none of the clinicians wore a face mask, giving rise to the speculation that droplet transmission of nasal and oropharyngeal flora was the most likely explanation for these infections.
In October 2005, the Healthcare Infection Control Practices Advisory Committee (HICPAC) reviewed this evidence as well as cases of bacterial meningitis and epidural abscesses previously reported in the literature.3-18,20-21 HICPAC concluded that there is sufficient evidence to warrant the additional protection of a face mask worn by the individual placing a catheter or injecting material into the spinal or epidural space.19 Thus, the CDC recommends wearing a mask when carrying out these procedures, including myelograms and lumbar punctures. The recommendation is categorized on the basis of existing scientific data as “1B”: Strongly recommended for implementation and supported by some experimental, clinical, or epidemiologic studies and a strong theoretical rationale. (A category “1A” recommendation would be based on strong support by well-designed experimental, clinical, or epidemiological studies.)
The decision by HICPAC and CDC to recommend wearing a mask was based in large part on evidence that face masks are effective in limiting the dispersal of oropharyngeal droplets13 and are currently recommended as an evidence-based practice for the placement of central venous catheters.19,22-24 Although the absence of a mask during initiation of spinal or epidural anesthesia may not necessarily cause the patient to develop an infection, most evidence points to the fact that it makes the procedure a safer one. It would appear that not wearing a mask is hard to justify when identical organisms have been grown from patient cultures and nasal swabs from anesthesiologists who did not wear a mask.

References:
1) WHIOTV.com. State releases report on Logan Co. meningitis. June 8, 2009. Accessed at:
www.whiotv.com/news/19692596/detail.html.
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