RESULTS
Five patients with no clinical evidence of COVID-19 underwent tracheostomy: 2 patients who underwent radical tonsillectomy, modified radical neck dissection and free anterolateral thigh flap reconstruction for carcinoma of tonsil; 1 patient who underwent maxillary swing nasopharyngectomy for recurrent nasopharyngeal carcinoma; 2 patients who underwent tracheostomy for aspiration pneumonia and sputum retention. Average operation duration was 352.4 (338.0-365.0) s. Droplet contamination was noted on all 5 plastic sheets. (Table 2) Droplet size ranged from 0.2mm to 2.8mm. Droplet contamination was most severe over the central surface for all patients with an average of 91.5% (86.7%-100.0%) followed by the left lateral surface and right lateral surface at 5.2% (6.7%-10.0%) and 3.3% (6.7%-10.0%) respectively. (Table 3)
Droplet count contamination was mainly over the central upper half of plastic sheet overlying the site of operation in the lower neck. Total droplet count was highest along the centre-most column F at 25.9% (n=15). Droplet count decreased towards the periphery on both sides. The decline was greater on the left lateral surface at 10.3% (n=6), 6.9% (n=4), 3.4% (n=2), 3.4% (n=2), 1.7% (n=1) and 0% along columns G, H, I J, K and L respectively compared with columns E, D, C, B and A at 17.2% (n=10), 24.1% (n=14), 3.4% (n=2), 1.7% (n=1) and 1.7% (n=1) respectively on the right lateral surface. (Table 3)
No droplet splash was documented on face shields of both the surgeon and scrub nurse for all patients.