Effect of laryngoscopy on middle ear pressure during anaesthesia induction.

AIMS The procedure of laryngoscopic orotracheal intubation (LOTI) has many impacts on several parts of the body. But its effect on middle ear pressure (MEP) is not known well. The purpose of this study is to evaluate the MEP changes subsequent to insertion of endotracheal tube with laryngoscope. SUBJECTS AND METHODS 44 patients were included in this study with a normal physical examination of ear, nose and throat. A standard general anaesthesia induction without any inhaler agent was performed to the all patients. The MEP measurements for both ears were applied under 1 minute; before induction (BI) and after intubation (AI) with a middle ear analyzer. Also hemodynamic parameters were recorded before induction and after intubation. RESULTS Of the 44 patients were 25 women and 19 men with a 43.5±15.1 mean age. A statistically significant rise in MEP was seen in all patients subsequent to insertion of endotracheal tube (P<0.05). Mean right MEPs were BI: -9.5 and AI: 18.5 daPa. Also mean left MEPs were BI: -21.7 and AI: 29.1 daPa. The amount of increases in left and right MEPs were 50 daPa and 27 daPa, respectively. 20% increase in systolic blood pressure and 19% increase in diastolic blood pressure were determined after intubation. The mean heart rate was 76/min before intubation, whereas it was 102/min after intubation with a 34% increase. CONCLUSION In this study bilateral significant increases in MEP were determined subsequent to LOTI. Possible factors affecting MEP may be auditory tube, size and type of the blades, drugs and face masking time. But on the other hand in our opinion cardiovascular and haemodynamic response to LOTI has the most impact over the middle ear mucosa with mucosal venous congestion.