Laryngeal mask airway (LMA) is currently the most widely used supraglottic airway device with advantages of simple and fast placement, reduced anesthesia drug use, more stable hemodynamics, and less throat discomfort after anesthesia compared to endotracheal intubation. Some studies claimed the use of muscle relaxants or local anesthetics (sprays or lubricants containing local anesthetics) for the throat before LMA placement can reduce the dosage of induction agents and postoperative throat complications. In modern society, more and more elderly people undergo elective surgery with the need of general anesthesia. However, they are the more vulnerable population with tendency of greater hemodynamic changes with more induction agent usage. Propofol is one of the most used induction agents which may lead to a drop in blood pressure. The objective of this study is to observe whether the dose of propofol and the changes in hemodynamics can be reduced by using muscle relaxants or laryngeal local anesthetics in elderly who receiving general anesthesia with LMA insertion.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
TRIPLE
Enrollment
96
10% lidocaine spray 3 puff for the throat before induction
Normal saline spray 3 puff for the throat before induction
Intravenous cisatracurium 0.12 mg/kg during induction
Intravenous normal saline during induction
The dosage of intravenous propofol for the first subjects was predetermined for each arm, and the dosage for the subsequent subjects would be determined according to the response of the previous subjects using the Dixon's up-and-down method with a step size of 0.25 mg/kg. If the subjects had no movement and stable hemodynamic status during and after the laryngeal mask airway (LMA) placement, the predetermined dosage of propofol for the subsequent subject would be decreased by 0.25 mg/kg. On the other hand, if the subjects had obvious movement, failure to LMA placement, and significant hemodynamic changes, the predetermined dosage of propofol for the subsequent subject would be increased by 0.25 mg/kg.
Linkup Chang Gung Memorial Hospital
Taoyuan City, Taiwan
Propofol requirement
The minimal propofol requirement dose was defined as the median effective dose (ED50) of movement or increased mean arterial pressure (MAP) to no movement or stable MAP. The ED50 is the average of the crossover midpoints found during conducting the Dixon's up-and-down method.
Time frame: one minute after propofol infusion
Non-invasive blood pressure (NIBP)
Using the non-invasive blood pressure machine to collect the systolic blood pressure, diastolic blood pressure, and mean arterial pressure
Time frame: 0 minute, 1 minute, 2 minute, 3 minute, 4 minute, 5 minute, 10 minute after LMA placement
Heart rate (HR)
Using the electrocardiogram monitor to collect the real-time heart rate
Time frame: 0 minute, 1 minute, 2 minute, 3 minute, 4 minute, 5 minute, 10 minute after LMA placement
Oxygen saturation (SpO2)
Using the pulse oximeter to collect the real-time oxygen saturation
Time frame: 0 minute, 1 minute, 2 minute, 3 minute, 4 minute, 5 minute, 10 minute after LMA placement
Peak pressure (P peak) of the airway
One of the monitoring parameter demonstrated on the mechanical ventilator
Time frame: 0 minute after LMA placement
Mean pressure (P mean) of the airway
One of the monitoring parameter demonstrated on the mechanical ventilator
Time frame: 0 minute after LMA placement
Ease of jaw opening
A factor for evaluating the condition of LMA insertion
Time frame: Procedure (At the same time of LMA placement)
Ease of LMA insertion
A factor for evaluating the condition of LMA insertion
Time frame: Procedure (At the same time of LMA placement)
Coughing or gagging
Symptoms which suggest non-optimal condition of LMA insertion
Time frame: Within 1 minute after LMA placement
Hiccups
Symptoms which suggest non-optimal condition of LMA insertion
Time frame: Within 1 minute after LMA placement
Head or body movement
Symptoms which suggest non-optimal condition of LMA insertion
Time frame: Within 1 minute after LMA placement
Laryngospasm
Laryngospasm is defined as airway obstruction with assumption that LMA is correctly placed, which is also a factor for evaluating the condition of LMA insertion
Time frame: Within 1 minute after LMA placement
Attempts for LMA insertion
The number of attempts for LMA insertion
Time frame: Procedure (At the same time of LMA placement)
Complications
Including sore throat, dysphagia, dysphonia
Time frame: One hour after LMA removal
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