In reply

We thank Dr Glick and Dr Machlin for their thoughtful comments about our audit. ¹

The aim of the Stop Before You Block (SB4YB) campaign is to reduce the incidence of wrong-side block. ² For the SB4YB campaign to be considered a success, we believe two criteria must be met. First, it needs to be demonstrated that it is possible for institutions to achieve a very high level of compliance with a pre-block ‘time out’ moment. Second, it needs to be shown that maintenance of this high level of compliance over the long term is associated with a lower incidence of wrong-side block compared with a control group.

Our primary aim was to demonstrate that the first of these criteria was achievable. Prior to our study, the highest compliance rate in the published literature that we identified was 57%. ³ Our post-intervention compliance rate of 91% is a big improvement on this, and we hope that future audits will be able to demonstrate compliance rates closer to the theoretically ideal 100%. We disagree with the suggestion that anything less than 100% is inadequate. Introduction of the World Health Organization Surgical Safety Checklist resulted in a reduction in surgical mortality and morbidity despite post-intervention compliance with all six safety indicators being only 56.7%. ⁴

In the rare and concerning event of a wrong-side block occurring, significant persistent patient harm is actually unlikely to result from the block itself. The reason for taking them so seriously is that they may be suggestive of systemic problems with pre-block quality assurance processes. The rationale for persisting with the comprehensive checklist is that it mitigates risk for wrong-side blocks as well as other complications that are similarly rare and serious but preventable. Examples include blocking the wrong patient, performing a neuraxial block on a patient taking anticoagulants, giving a drug that a patient is known to be allergic to, or failing to have equipment to manage over-sedation or local anaesthetic systemic toxicity.

In each of these examples there is a direct link between adherence to a point on the checklist and risk mitigation. With the exception of wrong-side block, for immediate complications that occurred during our audit there is no corresponding point on the checklist. It is therefore spurious to suggest that failure of the checklist to protect against immediate complications is somehow evidence that the checklist would also fail to protect against wrong-side blocks.

Whether it is best to emphasise a single SB4YB moment, or whether it is better to persist with a broad checklist is a question that should be answered through further scientific enquiry. Given that the SB4YB campaign has so far failed to reduce the risk of wrong-side block since its inception eight years ago, ⁵ we think it is reasonable to explore other options.