ABC: back to basics with anaesthetic breathing components

Abstract

ABC: back to basics with anaesthetic breathing components Recent reports of anaesthetic accidents attributed to obstruction of breathing components have re-emphasised the need for constant vigilance in checking anaesthetic apparatus. A recent adverse incident occurred on our intensive care unit involving a heat and moisture exchanger ®lter (HMEF) through which it became virtually impossible to ventilate the patient. The patient, admitted earlier that day with acute severe asthma, suddenly developed high airway pressures, desaturated and ausc- ultation of the chest revealed little air entry. The inspired oxygen concentra- tion was increased to 100%, and the patient was hand ventilated using a Waters' circuit with the HMEF remain- ing in situ. Although this restored the saturation to 94%, the patient's lungs remained dif®cult to ventilate manually. A chest radiograph excluded pneumo- thorax, and subsequent removal of the HMEF resolved the situation. Later on testing, a high resistance was encoun- tered when blowing through the HMEF. Fortunately, the patient has suffered no subsequent adverse sequelae related to this incident. Following this event, a search on the Food and Drug Administration web- site for similar product problems was undertaken. It revealed 10 reports of obstructed ventilation due to HMEFs or breathing circuit ®lters in the last two years, seven of which had life-threaten- ing sequelae. Three of the episodes involved intensive care patients and ®ve involved patients undergoing routine anaesthesia (the remaining two were unspeci®ed). One patient suffered a pneumothorax and two had cardiac arrests. It was also noted that, on one occasion, the anaesthetist defaulted to the Ôanaphylaxis drillÕ in the event, and in another, the problem was thought initially to be due to patient anatomy, thus subsequent measures were taken to correct this, inevitably in vain. These reported incidents are most certainly a very small percentage of the total event-free usage of such components. However, the anaesthetic practitioner cannot ignore the potential of such life- threatening adverse sequelae. Whether obstruction of breathing components occurs as an act of criminal sabotage, product failure or accidental errors, the anaesthetist should always ensure a thorough check of all anaesthetic breathing components before they are used and retain a high level of suspi- cion of faulty apparatus when a patient suddenly becomes dif®cult to ventilate. H. J. Wise Poole Hospital, Poole BH122JB, UK