Why real divers use checklists

Every two years the New Zealand Health Quality and Safety Commission publishes its Serious and Sentinel Event Report. This is a collection of accidents, incidents or mistakes in the healthcare system that resulted (or could have resulted) in patient harm.

Consider some examples from recent reports:

• A patient listed for a tooth extraction under general anaesthetic ended up having all his teeth removed; a procedure intended for another patient on the same operating theatre list.
  
• A patient listed for neurosurgery was anaesthetised and positioned incorrectly. An incision was made on the wrong side before the error was discovered. Luckily this occurred before any surgery was performed on the brain.
  
• A patient having a joint replacement was anaesthetised and made ready for surgery before it was discovered that the correct implant was not available in the hospital.
  
• If you are wondering why I am pointing these out in an article in a diving magazine, then consider these diving scenarios (all based on fact):
  
• After preparing their rebreather, a diver turns the oxygen cylinder off because they won’t be diving for another hour. They then forget to turn it back on prior to entering the water. The diver becomes unconscious from hypoxia and drowns early in the dive.
  
• A scuba diver forgets to strap on their knife (which is later found in their dive bag). During the dive they become entangled in monofilament fishing line which they cannot cut, necessitating removal of scuba gear and a panicked ascent. The diver is treated for probable decompression sickness.
  
• Two scuba divers forget to review buddy separation procedures prior to a dive. They become separated on the bottom. One surfaces but the other does not, resulting in long period of separation, a solo dive and an alarm being raised about a ‘lost diver’.
  

All of these incidents, both the medical and diving events, have their roots in relatively basic errors or omissions. Although these errors seem clumsy when judged in hindsight, they are virtually inevitable in a system without safeguards, because human memory and judgement are simply not perfect. Thus we need safeguards, and the reason for including the medical examples in this discussion is that evidence-based error-preventing measures now permeating modern medical practice are of substantial potential relevance to diving.

The problem of patient harm arising from medical error has been a major concern for several decades. In the early 2000s the World Health Organisation convened a panel of experts to brainstorm various strategies for error-prevention in health care. One initiative that emerged from this process, targeted at errors occurring in and around surgical procedures, was the Surgical Safety Checklist (SSC). The SSC is performed in the operating room and comprises a series of checks undertaken at several points during a surgical procedure. There are predictable items on the checklist including confirmation of the patient’s identity, the operation they are having and the side-effects (if relevant), the patient’s allergies, and the presence of appropriate implants. SSC administration is also designed to be an event in which all the operating room team members participate and in which communication is specifically encouraged. For example, everyone must introduce themselves by name and role, and everyone gets an opportunity to express any particular concerns they have about the procedure.

The efficacy of this strategy was first evaluated in a study in which I was one of the Auckland leads. It was a multicentre study run at eight centres around the world in which the outcomes for 8000 patients undergoing surgery were evaluated before and after introduction of the SSC. Deaths in the period around surgery were halved and complications were reduced by over 30% [1]. This was such an extraordinary result that many commentators struggled to believe the data. However, since that time multiple studies from all over the world have demonstrated exactly the same thing: a simple, cheap intervention with no risk reduces deaths and complication in the peri-operative period.

If checklists work to defeat simple errors and omissions in the medical setting then they should also be effective in diving. Indeed, one of the precipitants for this article was a recent study by the DAN group in the USA [2]. They randomised 1043 real world scuba divers (performing 2041 dives) to use a checklist before diving or not. The checklist referred to items like: air on, tank pressure check, no leaks, weights present, alternate air source check, knife present, review signals with buddy, etc. The study showed that use of the checklist was associated with a 36% reduction in mishaps such as: need to buddy breathe, rapid ascent, low or out of air, buddy separation, entrapment and regulator malfunction. This study represents a compelling signal that pre-dive checklists work, even in normal scuba diving. They have even greater potential in more complex diving pursuits, such as the use of rebreathers.

There is often confusion about what constitutes a ‘checklist’. In activities such as assembling a rebreather, relative novices often use comprehensive manufacturer’s assembly lists as ‘checklists’. There is nothing wrong with this, but as they become familiar with the process these ‘checklists’ become unwieldy and are discarded in favour of memory.

The real safety value of checklists lies with much shorter lists used by inexperienced and experienced divers alike. These lists are refined down to key steps or processes which, if omitted, represent a real risk of compromising safety. An example, provided to me by Pete Mesley, for Inspiration rebreather preparation is attached on the inside of the cover and always visible during assembly (Figure 1).

Arguably the most powerful checklists are so-called check-and-response procedures where one person reads the list and another checks off or demonstrates the item. Pilots of large passenger planes are very familiar with such checklists and divers have begun to use them. For example, rebreather divers on Mike Ball’s Spoilsport out of Cairns, Australia, go through a short check-and-response checklist with the Divemaster immediately prior to jumping in the water (see Figure 2). This list contains only five items considered by the Mike Ball team to be critical to safety, and ensures that no diver will enter the water with a critical gas shut off, or the unit electronics off; all mistakes that have resulted in fatalities in the past..

Finally, despite all the evidence that checklists improve safety in both medicine and diving, there will always be doctors and divers who feel that their competence is being questioned or impugned by advice to use checklists. Nothing could be further from the truth. Such advice merely recognises that errors and omissions are an inevitable part of the human condition, and that in checklists we have a simple evidence-based tool to reduce their likelihood. Why on earth would we not do it?
References:
1.    Safe Surgery Saves Lives Study Group. A surgical safety checklist to reduce morbidity and mortality in a global population. N Eng J Med 2009; 360: 491–499.
2.    Ranapurwala SI et al. The effect of using a pre-dive checklist on the incidence of diving mishaps in recreational scuba diving: a cluster randomised trial. Int J Epidemiol 2016; 45: 223–31.