Equipment Problems. Preventable Anesthetic Deaths: Is “PaF” the Magic Dragon?

GLOSSARY AAGBI = Association of Anaesthetists of Great Britain and Ireland; APL = airway pressure limitation; AWS = anesthesia work station; BfArM = Bundesinstitut für Arzneimittel und Medizinprodukte; CIRS = Critical Incident Reporting System; DGAI = Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin; Fio2 = inspiratory oxygen fraction; ISO = International Organization for Standardization; PaF = pressure and flow Quite recently I anaesthetized a V.V.I.P. in a well-known hospital. I felt a little bit diffident about going through the drill of checking the connections on the Boyle’s machine, but to my great surprise—and to the surprise and discomfiture of the local staff—I found one of the cylinders wrongly connected. I feel it right to tell this story to accentuate that checking is imperative even in the most unlikely circumstances. —Sir Robert R. Macintosh (1949) In 1949, Macintosh1 published an article in the British Journal of Anaesthesia, in which he delineated the circumstances of several anesthesia-related deaths. His statement that “there should be no deaths due to anaesthetics” implied easily preventable causes. Meanwhile, we have learned a lot about “human error” and means to reduce it2 and have made great efforts to improve patient safety, but we also have to face the fact that there still are anesthetic deaths due to easily preventable causes. Seventy years ago, Macintosh1 held checking the apparatus to be imperative; this recommendation has been repeated many times by many colleagues (eg, Cooper et al3) and anesthesia societies (eg, Association of Anaesthetists of Great Britain and Ireland [AAGBI] et al4). Thus, a functional check of an anesthesia work station (AWS) before its use has become routine practice. Two aspects, however, may still allow faults to occur: (1) automatic self-check programs of current apparatuses do not cover all relevant aspects and have to be accompanied by personal checks of the user, which may not be performed properly, nevertheless conveying the impression of “technical” safety and (2) new faults may be introduced during turnover of patients. If the next case is started without retesting and ventilation problems occur, again, the assumption that the AWS has been tested (and has been functioning properly) may impede timely technical fault detection. At the same time, technological advances, for example, measurement of oxygen and carbon dioxide, have eliminated some of the old hazards. However, there still are cases of inadvertently low inspiratory oxygen fraction (Fio2) due to mix-up of air or nitrous oxide with oxygen. On the part of the AWSs, new technologies have increased the level of complexity. The anesthesiologist may become someone who is using the AWS as a “black box,” rather than having a thorough understanding of its internal functions–comparable to “what is under the hood” of modern cars. All these factors can contribute to a problem which, although not entirely new, has caused attention in the recent past. Several cases of falsely connected hoses of the anesthetic breathing circuit have been disclosed on the German Critical Incident Reporting System medical platform (“CIRSmedical” platform; https://www.cirsmedical.ch).5 In addition, 7 serious incidents were reported to the German Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte [BfArM]) in the years 2013–2019, culminating in 2018: 1 fatal outcome, 2 permanent hypoxic brain injuries, and 1 circulatory arrest; the other patients were temporarily hypoxemic. One case in France resulting in the patient’s death has been published recently,6 and 1 case in Poland in 2013 with fatal outcome has been communicated to the manufacturer of the involved AWS. Wrong connections between the 22-mm cones on the AWS’s ports, the Y-piece, possibly water traps or nebulizers, and the 22-mm sockets on the ends of the hoses can be made in several ways; 2 types of misconnections were involved in the reported cases: A. The reservoir bag is inadvertently connected to the expiratory port of the AWS. In today’s AWS with fresh gas decoupling, this setting mimics a large leak. The bag does not fill even with high fresh gas flows. At the same time, these flows and the consequential high airway pressure are transferred to the lungs via the other 2 hoses connecting the Y-piece to the inspiratory and bag port, eventually resulting in barotrauma and pneumothorax. B. An accidental shortcut of breathing tubes: a connection between the inspiratory and expiratory port of the AWS, excluding the y-piece (“shortcut”), a maneuver deliberately performed for leakage search. The patient is pneumatically not connected to the AWS, imitating bronchospasm and making ventilation impossible. However, these misconnections in the respiratory circuit only result in a catastrophe, if 2 other conditions are also met: First, the wrong connection is not identified before connecting the patient. Because the automatic self-test usually does not detect this type of misconnection, this may be the case, if no additional inspection or check is done by the anesthesiologist. Second, inappropriate crisis management without timely resort to an operator powered resuscitator (eg, self-inflating bag, Ambu bag) as a means to reduce complexity and as a diagnostic tool to distinguish between patient problems and those on the circuit/AWS side. Typically, a fixation failure—“The machine has been checked, it must be bronchospasm.”—is involved. It has to be emphasized that all these cases could have been prevented if the anesthesiologist had routinely invested a few seconds for an additional quick check procedure—irrespective of the preceding thorough automatic (self-)check procedure of the AWS, for example, at the beginning of the working day. Recommendations in this regard have been made in the past, for example, the 2-bag test by the Association of Anaesthetists of Great Britain and Ireland (AAGBI).4 However, such additional checks “before each case” are not performed comprehensively, at least not in all situations, for example, when transferring a patient from the induction to the operating room. Apart from a lack of enforcement, a 2-bag test is tedious in situations like the change from the induction to the operation area. Nevertheless, some type of device check has to be considered as a mandatory part of the anesthetic, whenever a patient is connected to an AWS. This AWS-QUICKcheck7 is taking all known cases of AWS’s failures that triggered fatal outcomes within the last 15 years into account. This check takes only a few seconds and has to be done whenever a patient is connected to an AWS, for example, with induction or after transport and connection to another AWS. The AWS-QUICKcheck verifies 4 things: Is an operator powered resuscitator (self-inflating bag) available? - It should be used in case of ventilation difficulties to distinguish problems on the patient-side from the airway opening from those on the device-side. Is the desired Fio2 delivered? - or inadvertently air or nitrous oxide? Are the lungs ventilated? - proven by capnometry Is the anesthetic circuit functioning correctly, by and large? - proven by the “Pressure and Flow-Test” (“PaF” test) before connecting the patient - several manual ventilation hubs before mechanical ventilation is initiated An important part of the AWS-QUICKcheck is the PaF test. It is performed before the patient is connected and allows a rough assessment of the anesthetic circuit. It takes only a few seconds: the airway pressure limitation (APL) valve is set to approximately 30 mbar, the patient opening of the anesthetic circuit is closed, then the integrated reservoir bag is taken and compressed while the oxygen flush is activated. The bag must maintain the pressure, indicating the absence of major leaks (“Pressure”). Then the patient opening is released and gas has to exhaust audibly (onomatopoeic “paff”) indicating correct assembly of the system and absence of major obstructions. All above-mentioned misconnections would have been detected by a PaF test performed, and patient harm could have been avoided. The QUICKcheck is a routine procedure that is performed before the problem even occurs. Crisis management, on the other hand, only becomes necessary after the problem has arisen and requires targeted action under temporal and emotional pressure. Likewise, all these cases could have been prevented by a more appropriate approach to problem solving, mainly by disconnection of the patient at an early stage and the use of a manual resuscitator, followed by a systematic search for sources of leakage or obstructions. Therefore, algorithms for systematical fault finding in such situations, as recommended, for example, by the German Society for Anesthesiology and Intensive Care (Deutsche Gesellschaft für Anästhesiologie und Intensivmedizin [DGAI]),7 should be an elementary component of anesthesia education and should be practiced regularly within the framework of simulation training. Of course, a new design of the hoses and connection ports in the anesthetic circuit could prevent wrong connections, too. Currently, this is discussed in the relevant committees of the International Organization for Standardization (ISO) and will take time to be standardized and implemented. Thus, BfArM and DGAI would like to emphasize the importance of both, current approaches toward design changes and increased awareness for the described risks, including the need for adequate checks and appropriate crisis management by the anesthesiologist. DISCLOSURES Name: Thomas Prien, PhD. Contribution: This author helped develop recommendations and regulations aiming at prevention of equipment problems and devise the manuscript. Name: Andrea Brinker, MD. Contribution: This author helped collect and analyze most cases, develop recommendations and regulations aiming at prevention of equipment problems, and revise the manuscript. Name: Kathrin Pfeiffer, BEng. Contribution: This author helped collect and analyze most cases and revise the manuscript. Name: Hugo K. Van Aken, PhD. Contribution: This author helped develop recommendations aiming at prevention of equipment problems and revise the manuscript. This manuscript was handled by: Jean-Francois Pittet, MD.