Intensity and adequacy of laryngoscope light in seven intensive care units

Introduction

The objective of the study was to determine the adequacy of illumination of laryngoscopes in seven critical care units (CCU) (two medical, three surgical, two neurosurgical). Laryngoscopes in the Cleveland Clinic are routinely checked twice daily by healthcare workers. Confirmation of the presence of bulb illumination in ambient room light, however, may not be a sufficient test. In the CCU environment successful tracheal intubation may be time sensitive, and failure of adequate illumination of the larynx impedes visualization. Adequacy of lighting is subjective; however, the Health and Safety Executive suggests 500 Lux as a minimum for work requiring the perception of fine detail [1].

Methods

In a single-day spot audit, all clinically available laryngoscopes were evaluated for brightness. Battery voltage was measured with a voltmeter (Innova 3320; Fountain Valley, CA, USA), then the batteries were replaced for new prior to re-measuring of illumination. The bulb was then replaced for new and the illumination measured again. Illumination measurements were taken from tip of the blade at 90° using a luxometer (Model CA813; AEMC instruments, Foxborough, MA, USA) in a lightproof box.

Results

Forty-six laryngoscopes were tested. All had traditional vacuum incandescent bulbs. Twelve (26%) fell below 1,000 Lux and six (13%) fell below the 500 Lux minimum. The failures were corrected by battery replacement in 25% and by bulb replacement in the remaining 75% (see Figure 1).

Figure 1

Laryngoscope illumination.

Conclusions

Simply checking laryngoscopes for the presence of illumination on a regular basis is insufficient to ensure best or even adequate function. Poor function is as frequently related to bulb dysfunction as battery fatigue. Institutions should consider quality control and maintenance programs or consider more advanced laryngoscopic lighting (for example, LED or halogen bulbs).