The Slog Continues

7) Do anaesthetists need to wear surgical masks in the operating theater? A literature review with evidence-based recommendations

Abstract:

Many operating theatre staff believe that the surgical face mask protects the healthcare worker from potentially hazardous biological infections. A questionnaire-based survey, undertaken by Leyland' in 1993 to assess attitudes to the use of masks, showed that 20% of surgeons discarded surgical masks for endoscopic work. Less than 50% did not wear the mask as recommended by the Medical Research Council. Equal numbers of surgeons wore the mask in the belief they were protecting themselves and the patient, with 20% of these admitting that tradition was the only reason for wearing them. Policies relating to the wearing of surgical masks by operating theatre staff are varied. This indicates some confusion about the role of the surgical mask in modern surgical and anaesthetic practice. This review was undertaken to collate current evidence and make recommendations based on this evidence.

Aesop summary: This isn't even an actual study. It's a survey of old studies. Imagine you wanted to study the beach, but you were too lazy to actually go to the beach, and study it. So instead, you listened to old Beach Boys songs, while looking at postcards from beaches. Then made recommendations based on places you'd never been to, based on pictures from 10 to 40 years old. That's what a meta-survey is. But wait, there's more!

"Many operating theatre staff believe that the surgical face mask protects the healthcare worker from potentially hazardous biological infections." Point of Order: In actual healthcare, we call those people "morons". I mean that clinically: people with an IQ of 51-70. I may be over-generous in that assessment.

And bear well in mind, the "current evidence" these pseudo-researchers did was the exact studies we just described, and more like them. The plural of bullshit is not "evidence".

And to put a very fine point on this foray, they looked at zero studies referencing anything to do with mask impact on the transmission of aerosolized viruses. So the applicability of this to Nurse Claire's premise is...

0 for 7. Batting average steady at 0.000. Go team!

8) Patient surgical masks during regional anesthesia. Hygenic necessity or dispensible ritual?

Abstract:

Objective: The use of surgical face masks (SFM) is believed to minimize the transmission of oro- and nasopharyngeal bacteria to wounds and surgical instruments. However, there are disadvantages for patients undergoing regional anaesthesia and wearing masks: deficient assessment of lip cyanosis, anxiety, retention of CO2, costs. Up to now no studies have been published investigating whether or not SFMs, worn by patients during regional anaesthesia, will reduce bacterial convection.

Methods: We investigated 72 patients during aseptic operations: 24 individuals with regional anaesthesia and SFMs, 22 individuals with regional anaesthesia without SFMs and 26 patients undergoing general anaesthesia. Using an air sampler (volumetric impaction method) 100 L air were collected on blood agar over 2 min. After incubation at 37 degrees C over 60 h the colony forming units (CFU) were counted and differentiated. Airborne culturable bacteria were sampled over the operation field, on the anaesthetic side of the surgical curtain, as well as 10 cm before and to the side of the patients mouth.

Results: At all 4 locations there were no significant differences in the number of CFUs between patients wearing a SFM or not (e.g. over the operation field: patient with SFM 5.5 +/- 1.1; no SFM 4.8 +/- 1.2; mean +/- SEM). Significantly more CFUs were detected in patients undergoing general anaesthesia (p < or = 0.05). The extent of the operation did not correlate with the number of CFUs; however, we observed a trend that more CFUs were detected with an increasing number of persons working in the operating room.

Conclusion: Surgical face masks worn by patients during regional anaesthesia, did not reduce the concentration of airborne bacteria over the operation field in our study. Thus they are dispensable. A higher airborne germ concentration has been detected in patients during general anaesthesia. The reasons for this finding are unknown, but it may be discussed as being a result of a higher activity and number of staff involved during general anaesthesia causing more air turbulence.

Aesop summary: Statistically, 72 patients is a pitifully insignificant number, and the results are thus as much the work of the Underpants Gnome as any statistician. The significant finding is that more people in the room correlated to more infectious material. "The reasons for this finding are unknown, but gobbledygook bletharology air turbulence, because reasons." Apparently it was too great a stretch to simply note and concede that people are simply a mass of infectious material, from dawn to dusk.

And once again, nothing whatsoever to do with mask safety, efficacy, or utility in stopping the spread of aerosolized virus outbreaks.

9) Peritonitis in CAPD: to mask or not?

Abstract:

Objective: To assess the efficacy of wearing a face mask to prevent peritonitis during continuous ambulatory peritoneal dialysis (CAPD) bag exchange.

Setting: Renal unit at a university hospital.

Patients: Two groups of patients on CAPD were compared: those performing bag exchange with (n = 24) and those without a face mask (n = 40).

Outcomes: Occurrence of first episode of peritonitis and total number of episodes.

Results: No difference was found between groups with respect to probability of developing the first episode of peritonitis (p = 0.757). Patients holding university degrees had evidence of protection, with borderline significance [relative risk (RR) 0.52; confidence interval (CI) 95%, 0.23 -1.18; p= 0.109]. Cox's proportional hazard regression analysis also demonstrated a significant protective factor for patients with university level education (RR 0.42; Cl 95%, 0.18 - 0.98; p = 0.04). Incidence of peritonitis was not significantly different between groups: with-mask group had 1.0 episode/year, and without-mask group had 0.94 episodes/year. Staphylococcus epidermidis was the most commonly identified agent. Staphylococcus aureus was found more frequently in the with-mask group (p = 0.003). Peritonitis due to Streptococcus viridans and Enterococci were detected only in the without-mask group.

Conclusion: The current study suggests that routine use of face masks during CAPD bag exchanges may be unnecessary and could be discontinued.

Aesop summary: uses a ridiculously small and statistically insignificant patient sample, for a procedure virtually foolproof, to study incidence of a particular infection rarer than drowning, but not quite as rare as scorpion stings. Extrapolating from this dubious sample-set, concludes based on insignificant data that masks (which probably never needed to be worn) probably don't need to be worn. On a par with studies asking why robbers rob banks, or building a museum of cheese in Wisconsin with taxpayer money.

Validity: Nil. Even to what it was looking at.

Applicability to the prevention of infections by aerosolized Viruses: Nil.

Jesus, Mary, and Joseph: if someone got paid actual money for churning out this kind of pure bull squeeze, I'm in the wrong end of the business. I thought this kind of thing was best reserved for use in fertilizing rose bushes.

Nurse Claire has thus provided us with 9 total wastes of electrons and bandwidth, and failed to prove anything like her conclusion that masks won't stop the spread of aerosolized virus in society.

Based on a total dearth of any evidence whatsoever in support of that point, after looking at nearly 20% of the total number, if every other study left (42, at current count) is absolutely spot-on, the best grade she can earn is now a B-. If they're all as poorly constructed as the first nine have been, the score will be O-fer. As in O for EVER.

But wait! There's more!