Avoiding incidence of unintended awareness

Following numerous reported incidents of unintended awareness during surgery associated with the use of total intravenous anaesthetic (TIVA), the NHS National Patient Safety Agency established an investigative body of anaesthetists, called the Safe Anaesthesia Liaison Group (SALG). After a review of safety issues in relation to the delivery of anaesthetic agents, the group responded by issuing a notice entitled: “Guaranteeing Drug Delivery in TIVA”. Supported by the Society for Intravenous Anaesthesia (SIVA UK) and European Society for Intravenous Anaesthesia (EURO SIVA), the guidance pointed out that unintended awareness during surgery may occur with all techniques of general anaesthesia. However, when TIVA is used to maintain anaesthesia, unintended interruption of the continuous infusion of anaesthetic agents can lead to awareness if not detected promptly and corrected. “The incidence of unintended awareness during surgery is approximately 0.15%. This increases to 1% in high risk patients,” explained Dr William McFadzean, consultant anaesthetist, Werndale Hospital. “It is worth noting that the incidence is about the same in paralysed and nonparalysed patients. However, the psychological effects of awareness under anaesthesia, producing post traumatic stress disorder, are greater in paralysed patients,” he continued, adding: “It is very difficult to keep an accurate record of unintended awareness. Delayed recall can occur in which a negative experience may only become apparent some time after the operating procedure. “Indeed, the traumatised patient may exhibit a phobic avoidance of medical personnel particularly those involved in the incident. This makes it very difficult to screen patients for awareness. Any episode of awareness that is discovered must be fully investigated with the patient referred for specialist psychological advice and treatment if necessary.” One report received into the national Reporting and Learning System (RLS) described an incident whereby TIVA was administered to a patient via a multilumen connecter. There was no one-way valve in the connector and, as a consequence, there was backflow of anaesthetic agent into the limb of the intravenous fluid line, rather than directly into the patient’s vein. As a result of this, the reporting anaesthetist was concerned the patient may have experienced awareness during the anaesthetic. A search of data from the national Reporting and Learning System (RLS), from March 2008 to 15 June 2009, identified 89 safety incidents involving anaesthesia, which were subsequently reviewed, and the resulting analysis helped inform the development of the SALG guidelines. Key issues identified as a result of the analysis included the following:

• There were ten incidents involving nonavailability of appropriate pumps; in two cases this was because the pumps had not been charged.
• There were 11 incidents involving problems with pumps during TIVA; in one case the TIVA technique was abandoned; in eight cases the problems were noted immediately and the pump either changed or managed differently; in one case it was only noted at the end of the surgery that the pump had not delivered the appropriate amounts of agent.
• Two reports were of syringes being “switched” with one relating to wrong labelling, and one where a 1% solution was used instead of 2%.
• Three cases were reported where lines had been pulled out in error and one where the cannula had “tissued”.
• One case was reported where the anaesthetist was not familiar with the technique.
• There were three cases of potential awareness reported but with no problems with TIVA being identified.
• 18 cases reported problems with the intravenous line: three related to Y connectors and three related to 3-way taps. 
• Other incidents included kinking of lines, blocking of the line, luer lock leaks and other leaks from lines, and assumed fixed valves in lines becoming disconnected.

Out of the above incident reports, five were reported where there was possible awareness intra-operatively; and three situations were described where there was the potential for awareness. Based on these findings, the guidance recommends: 
• When administering TIVA, a nonreturn valve should always be used on any intravenous fluid line. 
• Sites of intravenous infusions should be visible so they may be monitored for disconnections, leaks or infusions into subcutaneous tissue. 
• When using equipment, it is essential that clinical staff know its uses and limitations.
• Organisations should give preference to clearly labelled intravenous connectors and valves.