|Year : 2010 | Volume
| Issue : 1 | Page : 25-28
Comparison of two regimes of thiopental and propofol for I-gel supraglottic airway device insertion
Yasser Mohamed Amr, Sabry M Amin
Department of Anesthesia, Tanta University Hospital, Tanta University, Tanta - 31527, Egypt
|Date of Web Publication||16-Sep-2010|
Yasser Mohamed Amr
Department of Anesthesia, Tanta university Hospital, Tanta university, Tanta - 31527
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: The I-gel mask is a novel supraglottic airway device. The objective of this study is to compare the insertion conditions for I-gel, using thiopental in two dosage regimes and propofol.
Materials and Methods: A prospective, randomized, double-blind design was used. Ninety patients included in the study were classified at induction into group I that received intravenous 2.5 mg.Kg-1 propofol, group II that received 6 mg.Kg-1 thiopental and group III that received 7 mg.Kg-1 thiopental. Mean arterial blood pressure (MABP) and heart rate (HR) were recorded immediately before, after insertion and 5 minutes later, as well as the baseline hemodynamic variables. Tolerance of I-gel insertion was assessed using a scoring system.
Results: Insertion conditions for I-gel supraglottic airway device showed significantly higher incidence of jaw relaxation (P=0.0008, 0.02 in groups I and III, respectively). No significant difference was found in the incidence of breath holding, lacrimation and stridor between the groups (P>0.05). The incidence of coughing/movement was significantly less in groups I and III (P=0.012, 0.04, respectively). Insertion time was significantly less in groups I and III (P<0.0001). The changes in MABP and HR were significantly less in groups I and III (P<0.0001).
Conclusion: The use of thiopental at a dose of 7 mg.Kg-1 as an induction agent produced comparable I-gel supraglottic airway device insertion conditions with 2.5 mg.Kg-1 propofol in comparison to thiopental at 6 mg.Kg.-1.
I-gel, propofol, thiopentol
|How to cite this article:|
Amr YM, Amin SM. Comparison of two regimes of thiopental and propofol for I-gel supraglottic airway device insertion. Anesth Essays Res 2010;4:25-8
|How to cite this URL:|
Amr YM, Amin SM. Comparison of two regimes of thiopental and propofol for I-gel supraglottic airway device insertion. Anesth Essays Res [serial online] 2010 [cited 2021 Jan 22];4:25-8. Available from: https://www.aeronline.org/text.asp?2010/4/1/25/69302
| Introduction|| |
Previously, the gold standard for securing the airway had been by tracheal intubation. However, the effective use of tracheal intubation requires a certain level of skill and experience. An ideal supraglottic airway device should be inserted rapidly with minimal training and it should enable controlled ventilation.  The I-gel mask was introduced in 2005 as a novel supraglottic airway device.  It has a gel-filled anatomical mask, a gastric drain tube and no cuff. An airway device without a cuff seems to have potential advantages (e.g. easier insertion and use, stability after insertion). 
It has been shown that insertion of supraglottic devices requires lighter anesthesia levels than that required for endotracheal intubation.  Since the time required for insertion was longer with inhalational anesthetics, intravenous agents have been preferred. 
Propofol has been used commonly as an induction agent for supraglottic airway device insertion. It provides smooth induction and depression of airway reflexes, allowing easier insertion.  However, propofol is expensive and causes pain at the injection site, which can be reduced by admixture with lignocaine or prior administration of thiopentone. , The objective of this study is to compare the insertion conditions for I-gel supraglottic airway device, using thiopental in two dosage regimes and propofol.
| Materials and Methods|| |
After obtaining approval from the hospital ethics committee and written informed consent, this study was carried out on 90 patients ASA I and II scheduled for different surgical procedures.
- Patients with body mass index (BMI)>30 kg.m 2
- Oral or nasal surgery
- Anticipated or known difficult intubation or ventilation
- Patients with limited mouth opening (less than 2 cm)
- Patients at increased risk of aspiration, or having a history of symptomatic gastroesophageal reflux or hiatal hernia.
A prospective, randomized (sealed envelopes indicate the group of assignment), double-blind design was used. The induction drug was prepared with the concentration of 10 mg/mL (propofol). To make the study blinded, we used different concentrations and a standard volume for thiopental. The syringe containing the induction drug was covered and the accurate dose for each patient (in milliliters) was calculated and was prepared in the syringe by an anesthesiologist and a chief nurse, blinded to the study design so that both the person administering the induction drug and the patient were blinded to the assignment group. All the patients were fasted for 8 hours and no premedication was given. After establishment of standard monitoring (non invasive blood pressure, ECG, pulse oximetry, capnography) conditions, intravenous access was secured. All the patients were preoxygenated with 100% O 2 for 3 minutes and then given intravenous lidocaine (2 mL, 10 mg/mL) before induction to avoid propofol injection pain and then the patients were classified into three groups:
The patients were ventilated via a face mask manually with assisted ventilation allowing spontaneous ventilation. After the completion of propofol bolus, or thiopental, loss of consciousness and eyelash reflex, the first attempt was made to insert an I-gel by a senior anesthesiologist [having 2 years experience with the laryngeal mask airways (LMAs)] blinded to group allocation and the patient was monitored.
- group I patients received intravenous 2.5 mg.Kg -1 propofol without any muscle relaxant;
- group II patients received 6 mg.Kg -1 thiopental without any muscle relaxant;
- group III patients received 7 mg.Kg -1 thiopental without any muscle relaxant.
A size 4 I-gel supraglottic airway device was used in patients weighing 50-90 kg and size 5 for patients above 90 kg.
Before insertion, a water-soluble lubricant was applied; the I-gel was grasped along the integral bite block and was introduced continuously into the mouth toward the hard palate until resistance was felt. An integrated gastric channel was provided for the suction of gastric contents or to allow the passage of a nasogastric tube to empty the stomach.
The I-gel supraglottic airway device then connected to the breathing circuit. Successful placement and adequate ventilation were confirmed by clinical observation of the clear airway, observing chest wall movement with manual ventilation, listening to escape of gas from the mouth, the absence of any air leakage with manual ventilation and the end-tidal carbon dioxide (ETCO 2 ). We recorded hemodynamic variables BP, heart rate (HR) immediately before and after insertion and 5 minutes later, as well as the baseline hemodynamic variables.
In order to assess the tolerance of I-gel supraglottic airway device insertion, we used a scoring system, a modified form of Muzi and colleagues.  According to this scoring system, we observed the patients for jaw mobility (1: fully relaxed, 2: mild resistance, 3: tight but opens, 4: closed) bucking/movement and others such as lacrimation, air leak, expiratory stridor and breath holding. If any movement occurred before insertion or after insertion, we added 0.5 mg/kg propofol or thiopental and waited for 30 seconds before the next attempt. If the third attempt was unsuccessful, it was to be recorded as a failure and the patient had an endotracheal tube inserted.
Insertion time was noted, i.e., the time (in seconds) taken from loss of eyelash reflex to successful I-gel insertion was recorded in the three groups.
The sample size required for the study was determined based on the primary outcome measures. Power analysis identified 30 patients per group, required to detect 30% difference between groups with a power 80%. Primary outcome measures of this study were time, number of attempts required and the secondary outcome measures were the hemodynamic data.
Data were analyzed using student's t test for the continuous variables like age, weight and hemodynamic parameters, and Fisher's exact test for the categorical variables. P<0.05 was taken as statistically significant.
| Results|| |
Ninety patients completed the study (30 patients in each group). There was no significant difference between the three groups in age, weight, gender ratio, height, duration of anesthesia [Table 1].
|Table 1: Demographic data of the groups, data presented as number of the patients or mean±SD|
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Changes in mean arterial blood pressure (MABP), and HR from the values recorded prior to intravenous (IV) induction are shown in [Table 2]. Though MABP decreased significantly in the three groups in comparison with baseline values (P<0.0001), the decrease was significant in groups I and III versus group II (P<0.0001). HR decreased significantly after propofol induction (group I) before insertion and then returned to the preinduction value (P values=0.004, 0.2, 0.3, respectively) and the same results were obtained with higher thiopental dose in group III, but in group II there was a significant increase in after insertion measurements in comparison to baseline (P values=0.17, <0.0001, <0.0001, respectively). There was a significant increase in HR in group II patients compared with groups I and III after induction (P<0.05).
|Table 2: Changes in mean arterial blood pressure (MABP), and HR, data presented as mean±SD|
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Insertion conditions for I-gel showed significantly higher incidence of jaw relaxation (P=0.0008, 0.02 in groups I and III, respectively) [Table 3]. No significant difference was found in the incidence of breath holding, lacrimation, and stridor between the groups (P>0.05) [Table 3]. The incidence of coughing/movement was significantly less in groups I and III (P=0.012, 0.04, respectively) in comparison to group II [Table 3]. Insertion time was significantly less in groups I and III (P<0.0001). Nine patients in group II required second attempt for I-gel insertion versus one patient in group I and two patients in group III.
|Table 3: Observed parameters and adverse events for I-gel insertion, data presented as number of the patients|
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| Discussion|| |
The authors present a prospective, randomized study of 90 patients, which compared three intravenous induction regimes for the insertion of the I-gel, a new, cuffless supraglottic airway. We conclude that 2.5 mg.Kg -1 of propofol was comparable to 7 mg.Kg -1 thiopental and both were superior to 6 mg.Kg -1 thiopental when considered in the context of 1) insertion time, 2) movement during insertion, 3) jaw relaxation, 4) and post-insertion hemodynamic parameters.
In Manikin study, the I-gel supraglottic airway device was the fastest supraglottic airway device to insert. 
Other study which recently described the use of propofol as a sole induction agent for successful I-gel supraglottic airway device insertion in 98% of the study patients. The authors speculated that a sole induction agent was enough for I-gel supraglottic airway device insertion.  So, we did not use premedication or drug combination in our study.
However, no additional benefits of increasing the dose of thiopental to 6 mg.Kg -1 instead of 5 mg.Kg -1 were observed in another study. That study assessed the conditions for insertion of the laryngeal mask following induction of anesthesia with either propofol 2.5 mg.Kg -1 , thiopentone 5 mg.Kg -1 or thiopentone 6.0 mg.Kg -1 in 120 patients premedicated with diazepam 10 mg. Insertion following induction with thiopentone 5.0 and 6.0 mg.Kg -1 resulted in a greater incidence of gagging.  In our study, we used 6 and 7 mg.Kg -1 thiopental and found comparable insertion conditions with that of propofol with the higher dose of thiopental.
Comparison of propofol versus thiopentone for facilitation of laryngeal mask insertion in another study  did not find any significant difference in the incidence of jaw opening, coughing, gagging, laryngospasm, and patient movement between thiopental and propofol groups, yet the insertion of LMA was significantly easier and time taken was significantly less in propofol group.
Conditions for insertion of the LMA were assessed in 70 unpremedicated patients comparing the co-induction with midazolam-alfentanil-thiopentone and midazolam-alfentanil-propofol with no significant difference. 
An admixture of thiopentone and propofol can produce suitable conditions compared to propofol 1%, for laryngeal mask insertion. In addition to cost containment, the admixture also produces less hypotension.  The co-induction with butorphanol and thiopentone produced excellent LMA insertion conditions compared to fentanyl and thiopentone. 
Meanwhile other authors concluded that although there was a faster induction with propofol-fentanyl, the conditions for insertion of the LMA were similar in both groups. Hemodynamic stability was better with sevoflurane-fentanyl. The propofol-fentanyl combination was more cost-effective. 
The broader clinical significance of the findings in this study must be considered. The majority of anesthesiologists would not consider the difference in time of insertion to be clinically relevant. Likewise, the differences in post-insertion HR and MABP between the three techniques are of minimal clinical significance and in neither method exceed baseline hemodynamic values.
| Conclusion|| |
Increasing the dose of thiopental to 7 mg.Kg -1 instead of 6 mg.Kg -1 as sole induction agent produced comparable I-gel supraglottic airway device insertion conditions with that of 2.5 mg.Kg -1 propofol.
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[Table 1], [Table 2], [Table 3]