Influence of LMA cuff pressure on the incidence of pharyngolaryngeal adverse effects and evaluation of the use of manometry during different ventilation modes: A randomized clinical trial
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Background. Pharyngolaryngeal discomfort is a significant complication following the use of laryngeal mask airway (LMA). The present study aimed to investigate the relation of LMA cuff pressure and the occurrence of pharyngolaryngeal discomfort during spontaneous ventilation (SV), pressure support (PSV) and pressure control ventilation (PCV). Methods. A hundred and twenty patients, ASA I-III, were included in this study. Originally the patients were divided into three groups: the 1st group was left to breath spontaneously, the 2nd group was placed under PSV while PCV was used in the 3rd group. Each group was divided into two subgroups: A) intervention group (maintaining cuff pressure at 60 cmH2O, measurement in 10 min intervals) and B) observation group (no intervention in cuff pressure, measurement in 10 min intervals). Anesthesia was induced with propofol and fentanyl and maintained with sevoflurane in air/oxygen. Patients were assessed 2 and 24 hours post-surgery, for sore throat, dysphonia or dysphagia. Results. A and B subgroup comparison at 24 hours revealed a statistically significant difference in the presence of pharyngolaryngeal discomfort in the PSV group (10% versus 55% respectively, P=0.006). Furthermore, when assessing the effect of maintaining a constant cuff pressure regardless of mode of ventilation, significantly fewer adverse effects were observed (8.3% vs. 35%, P=0.001) when compared to the non-intervention subgroup. Conclusion. Maintaining LMA cuff pressure in values which do not exceed 60 cmH2O probably contributes in decreasing pharyngolaryngeal discomfort independently of ventilation mode. The ventilation mode which leads to the highest incidence of pharyngolaryngeal morbidity when cuff pressures are not closely monitored is PSV.