Abstract

Despite the stringent guidelines laid down by the American Society of Anesthesiologists for equipment checks, there are occasional reports of problems related to the equipment used to administer anesthesia. In this article, we discuss two important, albeit rare, problems associated with breathing equipment that have been reported in the literature. The rarity of these problems in itself may hinder early diagnosis because anesthesiologists do not usually consider these problems to be the cause of an ongoing patient morbidity. The first problem discussed here is the presence of a foreign body within the breathing system used to administer anesthesia. The second problem discussed is a kink in the breathing circuits that can precipitate lifethreatening problems if it is not detected early enough.

Keywords

anesthesia; disposable equipment: breathing circuits; foreign bodies;

1. Introduction

Science believes in pursuing a problem till a plausible solution is found. To recognize a particular kind of problem in itself is very important, but this only limits itself to caution rather than cure of the problem. In this article, we discuss two important, albeit rare, problems associated with breathing equipment that have been reported in the literature. The rarity of these problems in itself may hinder early diagnosis because anesthesiologists do not usually consider these problems to be the cause of an ongoing patient morbidity. Therefore, it is important to be aware of such problems and to quickly find solutions that can prevent and/or minimize the occurrence of such problems.

All anesthesiologists are trained to carry out systematic equipment checks before proceeding with any anesthesia. Nevertheless, several cases have been reported where an equipment malfunction or malformation has placed a patient’s life in jeopardy. ¹⁻³ This could also place the anesthesiologist’s career at risk. Such instances are increasingly rare, perhaps because of the clear and stringent guidelines laid down by the American Society of Anesthesiologists for equipment safety check.⁴ In this article, we wish to highlight two different causes of equipment-related problems that have been reported in the literature. To date, because no preventative strategies have been developed, the anesthesiologist must be cautious of the problems discussed. For each problem, we conclude by providing a scientifically sound solution that can help reduce the likelihood of these events from occurring. We hope that these suggestions will help to enhance patient safety.

2. Problem 1

First, we wish to report a case where a possible airway mishap was averted by meticulous equipment examination. A 35-year-old woman, American Society of Anesthesiologists physical status I, was scheduled to undergo laparoscopic cholecystectomy. Before the patient was transferred to the operating theater, the consultant anesthesiologist performed a routine machine and equipment check, after these checks had been carried out by a theater technician and a trainee anesthesiologist. The consultant anesthesiologist noticed a plastic crescent (approximately 2 cm long and 1 mm wide) adhering to one end of the lumen of the Y-connector of the breathing circuit (George Philips Medical Engineering Ltd., Thane, India) (Figure 1). This discovery was providential because this potential foreign body had gone unnoticed on visual assessment of the semitransparent circuit by all three inspectors. In fact, the consultant anesthesiologist only found the foreign body while lifting the circuit head-on towards his mouth to check the inspiratory and expiratory valves, and the flapping motion of the strip of plastic caught his eye. The defective Y-connector was replaced with a fresh one, after checking its lumina and ensuring that no foreign body was resident. The anesthetic proceeded without incident thereafter. No Y-connectors with similar defects have since been found at our institution.

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Fig. 1. Y-connector: (A) viewed from above; and (B) end-on view showing the adherent crescent piece of plast

2.1. Discussion

The problem in this case is that, although the anesthesia circuit is semi-transparent, the foreign body was missed on visual assessment of the circuit by three members of staff. It is not routine practice to inspect the lumina of the circuits visually, unless an obstruction to inhalation or exhalation in the circuit is detected. Foreign bodies of small sizes, as in this case, are unlikely to occlude the breathing circuit, but can cause obstruction of smaller airways with subsequent sequelae. In the event of aspiration into the airways, detection of this particular foreign body would have been difficult because of its radiolucent nature.

Krzanowski and Mazur reported a case where a residual Murphy-eye sliver of an endotracheal tube had been aspirated by a patient, and this incident was only noted when the patient coughed out the plastic bit after extubation.³ In retrospect, they proposed that all endotracheal tubes should be examined internally and externally before use.³ Another case has been reported where the inner sleeve of the Y-connector had broken while positioning the patient, resulting in an intraoperative circuit leak.⁵

2.2. Solutions

Based on the present case, we recommend that all anesthetic equipment included in the breathing circuit should be inspected internally and externally as far as possible. Furthermore, we suggest that an airway filter (heat and moisture exchanger) should be placed between the Y-connector and the endotracheal tube or laryngeal mask airway, which would prevent any unnoticed or hidden foreign bodies from entering patients’ airways.

3. Problem 2

It was recently documented that circuit kinks may cause potentially life-threatening obstruction to gas flow. This may lead to the “cannot ventilate” scenario and such problems are easily overlooked.⁶ The breathing circuit used in this case was long and had very shallow corrugations, allowing this problem to occur. The authors have stated that plastic tubes are very prone to develop kinks and they suggested that kinking of breathing circuits should be considered in the differential diagnosis of intraoperative high airway pressures.

3.1. Solutions

We wish to report a simple solution to this problem. Although the material used to manufacture the breathing tube shown in Figure 2 is plastic (Limb-O; Vital Signs Inc., Totowa, NJ, USA), it does not kink, even if it is twisted or rotated by 180º. We attribute this to the nature of the corrugations that are a lot deeper than those of other breathing circuits. We conclude that the use of breathing tubes with deeper corrugations will help avoid kinking and the resultant consequences. These circuits should be considered more widely, particularly when lengthy breathing circuits are needed or if the breathing circuits are likely to be hidden under surgical cover sheets, where the kinks may not be easily noticed.

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Figure 2 Limb-O breathing circuit does not kink even if it is rotated or bent by 180º.