ABSTRACT
Forty five patients, ASA physical status I and II were studied. They were scheduled for elective surgical procedures in supine or lithotomy positions, in which neuromuscular blockade was part of anesthetic technique and the use of laryngeal mask airway [LMA] was appropriate. They were classified as Mallampati class 3 or 4. Exclusion criteria included: cardiovascular, respiratory disorders, morbid obesity, esopilageal reflux, hiatus hernia, any contraindication of inhalatinn induction of anesthesia and diseases of the neck. The patients were randomly divided lhto tIlrbb groups, 15 patients each, according to the intubating device: Group I [n=15]: endotracheal tube [ETT] [Control group], Group II: [LMA] and Group III: laryngeal tube [LT]. Each patient received 0.2mg Atropine Sulfate, no other pre-medication was given. After pre-oxygenation, anesthesia was induced using Volatile Induction and Maintenance Anesthesia [VIMA], N2O:O, [1:1] in sevoflurane concentrations- increased from I MAC by I %, gradually, until there is loss of lash reflex, relaxation of jaw, absence of movement, and absent response to painful stimulus. ETT was inserted using the laryngoscope. The classic LMA was inserted according to the manufacturer's instruction manual. Size 3 was used in the females and size 4 for males. The LT was inserted according to manufacturer's instructions, size 3 was used for patients less than 155 cm, a size 4 for those between 155-180 cm, and size 5 for those taller than 180 cm. Systolic and diastolic arterial pressure [SAP, DAP], and heart rate [HR] were recorded; before induction, and before insertion of the ETT or airway device, and 1,5,10 and 15 min after airway cotablishment and before reversal of the residual muscle relaxant effect. Blood samples were collected before induction, 1,5,10 and 15 min after intubation or insertion of the airway device and just before extubation/removal of the device: to determine plasma epinephrine, norepinephrine and cortisol levels. There were no significant demographic differences between the three groups. The duration of insertion of the ETT was relatively the longest [29.2+/-11.7 sec], compared to the LT [17.7+/-4.6] which was the shortest. Airway pressure was 22.7+/-4.3 cm H20 in case of ETT, 17.6+/-8.1 in LMA and 29.3+/-5.1 in LT. Ventilation was excellent in case of ETT. In LMA, ventilation was excellent in 5 cases, it in 3, fair in 4 and poor in 3 patients. In case of LT [Group III], ventilation was excellent in 9 cases, good in 4, fair in I and poor in I patient. In EU, [GI], HR increased from 64.3+/-11.7 before induction to 97.1+/-9.4, and reached 101.5+/-8.7 just before extubation. In LMA it was 69.6+/-9.4 after introduction of device, compared to 62.9+/-9.1 in case of LT. just before removal of the device; HR in LMA was 81.6+/-17.4 and 83.2+/-11.2 in LT. In case of ETT there was an increase SBP. DBP tip to [143 +/- 19 and 93 +/- 15 mmHg] 1mm after intubation, [141+/-21 and 91+/-12 mmHg] before extubation respectively. This increase was higher than that detected with the insertion of LMA [127+/-12 and 74+/-11mmHg] and LT [115 +/-7 and 65 +/- 16 mmHg]. Just before removal of airway devices SBP and DBP reached [126+/-13 and 80+/-15 mmHg] with LMA and [119+/-15 and 73+/-14 mmHg]. The mean maximal epinephrine and norepinephrine plasma concentrations after insertion of the ETT [51.3+/- 23.3 and 248+/-83pg/mL] respectively. LMA [22.1+/- 11.2 and 163+/-63 pg/mL, respectively] and LT [23.1+/- 17.4 and 153+/- 67pg/mL, respectively]. Just before extubation they reached [81.4+/-22.5 and 363+/-82 pg/mL] in ETT group, [47.1+/-26.2 and 246+/-78 pg/mL] in LMA group and [43.6+/-24.6 and 233+/-66 pg/mL] in LT. Plasma cortisol reached up to 403+/-21 nmo/L 1 min after intubation in ETT, 342+/-19 nmo/L in LMA group, and 348+/-13 nmo/L in LT group. Just before extubation plasma cortisol was 613+/-41 nmo/L in ETT [Group I 363+/-23 nmo/L and 371+/-13 nmo/L in LMA and LT groups respectively