Abstract
Introduction
Orthopaedic theatres can be noisy.
Noise exposure is known to be related to reduced cognition, reduced manual dexterity and increased rates of post-operative wound infection. Up to 50% of orthopaedic theatre staff have features of Noise-Induced Hearing Loss (NIHL) with higher levels in consultants compared to registrars. Exposure to noise levels of 90dB(A) at work for a career of 40 years, equates to a 51% risk of hearing loss.
Materials & methods
A Casella CEL-242 meter was positioned in the corner of the theatre tent. Recordings were taken for 17 Total Knee Replacements (TKRs) and 11 Total Hip Replacements (THRs). This meter recorded the decibel level once per second (whereas EU Regulation requires equivalent continuous level measurement).
Results
Noise levels reached 105.6dB(A) using a hammer during a TKR and 97.9dB(A) with an oscillating saw. Decibel levels exceeded 90dB(A) in every operation within the sample. Percentages of readings at 80.0dB(A) or above, per case, were calculated to estimate the proportion of our data above the EU regulation Lower Action Level; the maximum was 12.6% and they appeared to be greater in TKRs.
Discussion
The small percentage of values at 80.0dB(A) or above indicates that the equivalent continuous decibel level for an average 8 hour day would be below the EU Lower Action Level. It was expected that TKRs would have higher percentages of decibels at 80.0dB(A) or above, given the greater time spent sawing in this procedure. Exposure to levels above 90dB (which occurred in every case) for short time periods is proven to cause irreversible loss of hearing. Minor damage accumulates throughout a career of 40 years, and can result in NIHL.
Conclusion
Tools used in orthopaedic theatre produce impulse noises that can cause NIHL. Average daily exposure can be assumed to be acceptable. Further investigation is required.
