ABSTRACT
This study was designed to investigate the effects of propofol, sevoflurane and position changes on respiratory mechanics. Forty patients scheduled for thyroid surgery were divided randomly into two groups; those receiving sevoflurane [group S] [n=20], and those receiving TIVA propofol [group P] [n=22]. Dynamic compliance [Cdyn], peak inspiratory pressure [PIP], and respiratory resistance [Rr] values were recorded with a VenTrak respiratory monitor [Novometrix Inc. USA] at three time instances. The first measurement was done immediately after the beginning of ventilation and before the inhalation agent was initiated [Induction]. Second measurement was done after 5 minutes of thyroid position [Thyroid] [ventilation with 1 MAC sevoflurane concentration or propofol infusion at the rate of 6 mg/kg/h].The third measurement was performed 5 minutes after end of surgery in the supine position [Supine] Blood gases were measured at the three time instances. Respiratory mechanics did not change in the P group [51 +/- 13, 46 +/- 11, 48 +/- 10 mL/cmH2O] at Induction, Thyroid and Supine positions]. In the S group, dynamic compliance measurements showed changes statistically significant in the supine position [52 +/- 6 mL/cmH2O]] when compared to Induction [47 +/- 9 mL/cmH2O] and Thyroid position [47 +/- 6 mL/cmH2O] measurements [p<0.05]. When the groups were compared with each other, there was no significant difference whatsoever at all periods [p>0.05]. this concluded that sevoflurane, propofol and position changes exhibit similar effects on respiratory mechanics and blood gases at described dose and concentration