Feasibility of face mask spirometry during decannulation in head and neck surgery: Prospective cohort study

Objectives To analyse the relationship between spirometric parameters measured with a face mask versus a mouthpiece, as well as the feasibility of face mask spirometric evaluation in a head and neck surgery (HNS) decannulation context. Furthermore, we examine peak inspiratory flow (PIF) cut-off values before and after decannulation. Design Prospective cohort study. Setting Otolaryngology HNS Department of a university teaching hospital. Participants Twenty-four patients were selected. A maximal flow-volume loop was conducted before (with mouthpiece) and after (with mouthpiece and face mask) decannulation. Main outcome measures Recorded outcomes were forced vital capacity (FVC), forced expiratory volume in the first second, peak expiratory flow, PIF, forced expiratory flow at 50% of FVC and forced inspiratory flow at 50% of FVC. Spearman correlation coefficients between spirometric parameters measured with a face mask versus a mouthpiece were calculated. Wilcoxon test was used to check differences between mouthpiece and face mask values. Results Correlation between mouthpiece and face mask spirometric values was moderate to high (r = 0.46-0.95). All parameters measured by spirometry were significantly lower with a face mask than those obtained with a mouthpiece (p < 0.05). Before decannulation, the lowest PIF value (tested with mouthpiece) that allowed successful decannulation was 1 L/s. After decannulation, the lowest PIF value tested with mouthpiece and face mask for successful completion of the decannulation process were 0.77 and 0.56 L/s, respectively. Conclusion Face mask is a feasible option to perform a spirometry when face diseases hinder spirometric evaluation through a mouthpiece in an HNC surgery context.