The effect of propofol/remifentanil rapid-induction technique without muscle relaxants on intraocular pressure

Study ObjectiveTo evaluate the effect of propofol (two mg/kg)/remifentanil (4 μg/kg) on intraocular pressure (IOP) when used for rapid-sequence induction.DesignRandomized, double-blinded trial.SettingAmbulatory surgery center.Patients47 adult, ASA physical status I and II patients (ages 18-75 yrs), undergoing outpatient, elective, nonophthalmologic surgery.InterventionsAfter premedication with midazolam (two mg) and glycopyrrolate (0.2 mg), standard monitors and a bispectral index (BIS) monitor were applied. Patients underwent rapid-sequence induction with intravenous (IV) propofol two mg/kg and either remifentanil 4 μg/kg IV or succinylcholine 1.5 mg/kg IV. An experienced anesthesiologist, blinded to patient group assignment, performed intubation after 60 seconds.MeasurementsIOP, heart rate (HR), blood pressure, BIS scores, intubating conditions, and response to intubation (coughing or moving) were recorded at baseline, immediately after completion of induction, one minute after intubation, and three minutes after intubation. Time to return of spontaneous ventilation was also measured.Main ResultsRemifentanil produced a 39% decrease in IOP immediately after induction, which remained unchanged by laryngoscopy and intubation (P < 0.001). IOP remained below baseline even in patients who coughed or moved in response to intubation. Remifentanil caused a significant decrease in mean arterial pressure of 24% to 31% but no significant change in HR, and it blocked the hemodynamic response to laryngoscopy and intubation while providing intubating conditions comparable to those of succinylcholine.ConclusionsPropofol/remifentanil induction provides adequate intubating conditions, prevents an increase in IOP, and controls the hemodynamic stress response to laryngoscopy and intubation.     

The effect on intraocular pressure of endotracheal intubation or laryngeal mask use during TIVA without the use of muscle relaxants

BACKGROUND: Depolarizing and non-depolarizing muscle relaxants possess many untoward side effects. In most patients endotracheal intubation may be performed with a propofol and alfentanil combination. The purpose of this study was to compare the effect on intraocular pressure (IOP) and haemodynamics of endotracheal (ET) intubation or laryngeal mask (LMA) insertion during total intravenous anaesthesia (TIVA) without the use of muscle relaxants. METHODS: In a randomised study, 20 patients scheduled for elective orthopaedic surgery were assigned to two groups of 10 patients. Anaesthesia was induced with i.v. alfentanil 40 micrograms/kg and propofol 2.5 mg/kg. LMA insertion or ET intubation was achieved by the same anaesthesiologist. Airway score, insertion score, patient response and haemodynamics were recorded. IOP measurements were recorded before and after induction, 1 and 2 min after ET intubation or LMA insertion, and 1 and 2 min after extubation. RESULTS: Mean arterial pressure and heart rate after insertion of the airway management devices was significantly higher than induction values in the ET group (P < 0.05), while during 2-3 min no significant changes were observed in LMA group. In all patients following propofol and alfentanil induction, IOP was significantly lower than preinduction values (P < 0.001). IOP following extubation was significantly higher than preinduction values in the ET group, but not in the LMA group (P < 0.001). CONCLUSION: During TIVA without the use of muscle relaxants neither LMA insertion nor ET intubation increased the IOP, but ET extubation did.     

Barrier pressure and muscle relaxants

The effects of pancuronium and vecuronium on the lower oesophageal sphincter pressure were studied in 24 healthy patients anaesthetised with 0.5% halothane in nitrous oxide and oxygen. Following pancuronium 0.1 mg/kg intravenously, there was a significant increase in barrier pressure from a control value of 2.0 (SEM 0.14) kPa to 3.0 (SEM 0.27) kPa 1 minute after injection (p less than 0.05). This increase was sustained throughout the 15 minute period of recording and was accompanied by a significant increase in heart rate (p less than 0.001). Following administration of vecuronium 0.1 mg/kg intravenously there was an initial modest, though not significant increase in barrier pressure. This increase was significant (p less than 0.05) at 15 minutes. There were no cardiovascular changes following vecuronium.     

Comparative evaluation of several muscle relaxants

The use of different muscle relaxants have been studied in two homogeneous groups of patients, in the first group atracurium and in the second succinylcholine-pancuronium. The utility of atracurium in short-medium abdominal surgery has been demonstrated.     

The effect on intraocular pressure of tracheal intubation or laryngeal mask™ insertion during sevoflurane anaesthesia in children without the use of muscle relaxants

BACKGROUND: We studied the effects of sevoflurane on intraocular pressure after induction in children undergoing either tracheal tube (TT) or laryngeal mask airway (LMA) insertion without a muscle relaxant METHODS: The study included 38 children. Anaesthesia was induced (8%) and maintained (3-4%) with sevoflurane in 100% O2. No muscle relaxant was used. A TT was inserted in group I (n=20), and an LMA in group II (n=18). IOPs were measured after induction, insertion of TT or LMA and at 1, 2 and 3 min thereafter. The heart rate, mean arterial pressures were also recorded. RESULTS: Intraocular pressures increased significantly in group I after TT (P < 0.01) and remained high until after 3 min. The pressures were similar in the LMA group at all measurements. CONCLUSION: Sevoflurane does not prevent the increase in IOP after intubation without muscle relaxants. LMA does not increase IOP in children after sevoflurane induction.