European Journal of Cardiovascular Medicine

Endotracheal intubation is the placement of a tube into the trachea, either orally or nasally for airway management. The patient is connected to the mechanical ventilator to provide continuous respiration with an endotracheal tube. Laryngoscopy and tracheal intubation, however, are associated with hemodynamic changes; caused due to intense sympathetic discharge on stimulation of epipharynx and laryngopharynx.^1,2

Failures during intubation during emergency or unanticipated situation has almost accounted for 1.5-8.5%.³ In difficult situation, many rescue maneuvers are employed which includes techniques like use of bougie, BURP maneuver etc. though, even these techniques are not fully effective in difficult scenarios and sometimes leads to failed intubation even after using all the techniques available. To overcome these technical difficulties, various video laryngoscopes has been brought into practice.³

Endotracheal intubation using direct laryngoscopy is the gold standard for establishing an airway and it is a fundamental skill for acute care practitioners. However, tracheal intubation using direct laryngoscope (DL) requires technical skills and is often difficult to acquire direct laryngoscopy, often requires alignment of the three axes (oral, pharyngeal, and laryngeal axis) in a straight line. This skill is difficult to master and has a long learning curve.^4,5 The advancement in digital technology has led to a number of video laryngoscopes (VLs) being developed for clinical use. Present study was aimed to compare time taken for intubation, hemodynamic parameters and POGO score between direct laryngoscope and video laryngoscope for endotracheal intubation in adult patients.

Present study was prospective randomized single blinded study, conducted in department of Anaesthesiology, at XXX medical college & hospital, XXX, India. Study duration was of 2 years (October 2020 to November 2022). Study was approved by institutional ethical committee.

Inclusion criteria

• Patients of age 18-60 years, ASA grade 1 & 2, weight 50-70 kg, Mallampatti grade 1 & 2, underwent endotracheal intubation, willing to participate in present study

Exclusion criteria

• ASA grade 3, 4 & 5
• Mallampatti grade 3 & 4
• Risk of gastric aspiration
• Patients with laryngeal & thyroid surgery
• Hypertensive &Ischemic heart disease patients

Study was explained to participants in local language & written informed consent was taken. History (complaints, medical fitness, drug history, personal history, past history and surgical history) & physical examination findings (general, systematic examination & airway assessment) were documented. Baseline investigation (CBC, urine examination) & special investigations (LFT, KFT, RBS, ECG, CXR, HIV, HBsAg.as per disease conditions) were done. 60 patients were randomly distributed using random number table in 2 groups.

• Group DL: intubated with conventional Laryngoscope (n=30)
• Group VL: intubated with Video Laryngoscope (n=30)

Patients were pre-oxygenated with 100% oxygen for 3-5 mins. Premedication were given with inj. Midazolam 0.02mg/kg and inj. Fentanyl 2ug/kg and inj. Ondansetron 0.08 mg/kg. Patients were induced with inj. Propofol 2-2.5 mg/kg and after confirming mask ventilation, muscle relaxant inj. Vecuronium 0.1 mg/kg was given.

Trachea intubated with appropriate size of endotracheal tube by an anaesthesiologist according to group allocation of patient. Placement of endotracheal tube was confirmed by capnography and chest auscultation. Anaesthesia was maintained with intermittent positive pressure ventilation, with 50% oxygen and 50% nitrous oxide and inj. Vecuronium 0.02 mg/kg and inhalation agent isoflurane. After the end of the surgery, muscle relaxation was antagonized with IV Neostigmine 0.05 mg/Kg & Glycopyrrolate 0.004 mg/Kg, anaesthetic gases were discontinued to 0% and will be replaced with O2 100%. Endotracheal tube was removed when the patient is awake and then the patients were transferred to the recovery room for monitoring of vital signs till transfer to the ward.

Patients were evaluated according to time taken for intubation, safety parameters and also post operatively. Intraoperatively and post operatively Heart Rate, Systolic BP, Diastolic BP, MAP, SpO2, ECG will be maintained before intubating the patient and after intubation, then every 10 minutes till the patient extubated and also postoperatively every 10 minutes in recovery room for 2 hours, the patient will be observed for side effects like hypotension, bradycardia, fall in oxygen saturation, hoarseness of voice, sore throat.

Data was collected and compiled using Microsoft Excel, analysed using SPSS 23.0 version. Frequency, percentage, means and standard deviations (SD) was calculated for the continuous variables, while ratios and proportions were calculated for the categorical variables. Difference of proportions between qualitative variables were tested using chi- square test or Fisher exact test as applicable. P value less than 0.5 was considered as statistically significant.

Distribution of age, gender & ASA grade was comparable among two groups & difference was statistically not significant (p>0.05). 40% from Group DL had MPC grade 1 as against 70% had Group VL. 60% from Group DL had ASA grade 1 as against 30% had Group VL. This difference in the number of subjects within each age group with respect to MPC grade was statistically significant (p<0.05).

60% from Group DL had Cormack–Lehane (CL) grade 1 as against 80% had Group VL. 30% from Group DL had Cormack–Lehane (CL) grade 2 as against 20% had Group VL. 10% from Group DL had Cormack–Lehane (CL) grade 3 as against 0% had Group VL. This difference in the number of subjects within each age group with respect to Cormack–Lehane (CL) grade was statistically not significant (p>0.05). Number of attempts required for intubation for Group DL single in 80% as against 100% for Group VL. This difference was statistically significant (p<0.05).

Optimization maneuver used for intubation for Group DL single in 100% as against 10% for Group VL. This difference was statistically significant (p<0.05).

Table 1: General characteristics

Mean age of the cases from Group DL and Group VL was 36.30±10.18 and 35.30±10.90 years. This difference in the mean age was statistically significant (p>0.05). Mean weight of the cases from Group DL and Group VL was 68.20±10.19 and 67.80± 10.93 kg. This difference in the mean weight was statistically significant (p>0.05).

Mean POGO score of the cases from Group DL and Group VL was 80±24.91 and 90±20.34. This difference in the mean POGO score was statistically non- significant (p>0.05). Mean ET insertion time of the cases from Group DL and Group VL was 16.30±2.23 and 18±2.03 seconds. This difference in the mean ET insertion time was statistically significant (p>0.05).

Table 2: Comparison of variables between Group DL and Group VL

We compared the heart rate between two groups. It was observed that mean heart rate in Group DL was significantly less as compared to Group VL after intubation 0, 5, 10, 15, 30 minutes as well as up to post operatively 30 minutes.

Table 3: Comparison of heart rate between Group DL and Group VL

We compared the SBP between two groups. It was observed that mean SBP in Group DL was significantly higher as compared to Group VL after intubation 10 and 15 minutes as well as up to post operatively 30 minutes.

Table 4: Comparison of SBP between Group DL and Group VL

We compared the DBP between two groups. It was observed that difference in the mean DBP in Group DL and Group VL at all the time intervals was statistically non- significant (p>0.05)

Table 5: Comparison of DBP between Group DL and Group VL

We compared the MAP between two groups. It was observed that mean MAP in Group DL was significantly higher as compared to Group VL after intubation 10 and 15 minutes (p<0.05)

Table 6: Comparison of MAP between Group DL and Group VL

We compared the SPO2 between two groups. It was observed that difference in the mean SPO2 in Group DL and Group VL at all the time intervals was statistically non- significant (p>0.05).

Table 7: Comparison of SPO2 between Group DL and Group VL

The failure of direct laryngoscopy to provide an adequate glottic visualization, coupled with a major pressor response, has led to the development of newer intubation devices. Video laryngoscope is one such intubation device with advantages of a higher success rate, better glottic visualization, safer intubation, faster learning curve, and the opportunity for dynamic interaction during airway management.⁶

We included total 60 subjects in our study. Group DL included 30 and Group VL included 30 cases. Number of attempts required for intubation for Group DL single in 80% as against 100% for Group VL. This difference was statistically significant (p<0.05).

Elhadi SM et al.,⁷ reported that regarding the number of trials, 10 patients needed more than one trial in the Macintosh group in comparison with four in the King video group, and this was not significantly different. Upasana Gupta et al.,⁸ reported that the number of attempts required to intubate the patients. If the anesthesiologist had to change the blade, it was considered a second attempt and If the patient could not be intubated after three attempts, it was considered as failure of intubation. More than one attempt was needed in 20% of the cases in group ML while only 3% in group VL and it was statistically significant.

Similarly, Jungbauer et al.,⁹ found that with video laryngoscopy, 99% patients were intubated in the first attempt, whereas with Macintosh 92% were intubated in the first attempt. This was statistically significant and agreed with the findings of our study. Dalal et al.,¹⁰ had similar findings. In contrast to our study, Studies by Malik et al.,¹¹ Barak et al.,¹² and Timanayakar et al.,¹³ found no significant difference in the number of attempts with both the techniques.

In our study, optimization maneuver used for intubation for Group DL single in 100% as against 10% for Group VL. This difference was statistically significant (p<0.05). Upasana Gupta et al.,⁸ reported that optimizing maneuvers such as BURP or Bougie required to facilitate intubation with both the techniques. In Group VL, only 16.6% of the patients required rescue manoeuvre to facilitate intubation, whereas 83.4% of the patients did not require any optimizing manoeuvre. In Group ML, 63.3% of the patients required optimising manoeuvre. These findings were statistically significant. Thus, the number of optimizing manoeuvres required to facilitate intubation is significantly less with TrueView EVO2 blade as compared with those using a Macintosh blade.

Dalal et al.,¹⁰ and Malik et al.,¹¹ had similar findings. Hemodynamic data were comparable in both groups and there was no significant difference.

Mean ET insertion time of the cases from Group DL and Group VL was 16.30±2.23 and 18±2.03 seconds. This difference in the mean ET insertion time was statistically significant (p>0.05). It means time required for ET insertion was more in video laryngoscopy (Group VL) as compared to Group DL.

Elhadi SM et al.,⁷ reported that the total tube insertion time was not significantly different between the two groups; the mean insertion time was 19.10±7.08 in group M and 17.34±4.62 in group K.

Panwar N et al.,¹⁴ reported that mean duration of tracheal intubation attempts in Group I was 18.50 11.25 seconds and Group D was 11.76 4.44 seconds. This difference in time of insertion was gross and statistically highly significant giving a P value of < 0.05 (P value=0.000). This shows that time required for tracheal intubation in Group I was significantly more as compared to Group D. Time to intubation was found to be significantly longer in the Glide Scope (15.9 6.7 seconds) than in the Macintosh group (7.8 3.7 sec) (P< 0.001).

Ramesh et al.,¹⁵ published that the time taken for intubation (TTI) was 23.11 s in the Macintosh Group and 33.62 s in the TrueView Group. He stated that intubation is performed in an indirect manner with TrueView that is seeing the tube and the cords through the lens, and focuses on the cords, then the endotracheal tube is passed blindly till the tip enters the TrueView visual field. It requires a good hand eye coordination and expertise. The anaesthetists who are new to this technique, experience considerable difficulty in advancing the tracheal tube toward the view of the lens; this may be the reason for increased TTI with TrueView.

Torun et al.,¹⁶ reported that the time for intubation in Macintosh Group was 23 s and in TrueView Group it was 42 s, which was statistically significant. Singh et al.,¹⁷ observed that in their study, the mean TTI in TrueView Group was 28.6 s.

In present study, mean heart rate in Group DL was significantly less as compared to Group VL after intubation 0, 5, 10, 15, 30 minutes as well as up to post operatively 30 minutes. SBP, DBP, MAP and SPO2 were comparable in both the groups with no significant difference.

Sonavane SR et al.,¹⁸ reported no significant difference was found in the baseline heart rate and the heart rate before laryngoscopy in both the groups of our study, there was a significant difference in the heart rate immediately after laryngoscopy and 10 minutes after intubation in both the groups with p value < 0.0001. Similarly, the baseline MAP and the MAP before laryngoscopy in both the groups had no significant difference. There was, however, a significant difference in the MAP immediately after laryngoscopy and 10 minutes after intubation in both the groups with a p value < 0.0001.

Upasana Gupta et al.,⁷ reported that in Group ML there was increased hemodynamic changes attributed to the handling and manipulation. It was less in Group VL, but the increased duration of time taken for intubation made it insignificant in comparison with group VL. In 2017, Mogahed et al.,¹⁹ observed that there was a statistically significant difference in the heart rate and MAP between the Macintosh group on one side, with no significant difference between the C-MAC D blade and the KVVL group. Sonavane SR et al.,¹⁸ also reported that the mean SpO2 was maintained (99%) in both the Macintosh and KVVL groups throughout the procedure.

The VLs have now become a widely accepted method of the airway management as it facilitates easy visualization of the glottis without the need of proper alignment of the oral, pharyngeal, and laryngeal axes.^20,21 The short learning curve of VL makes it an attractive choice in inexperienced hands.²²

Mean ET insertion time was significantly more in video laryngoscopy as compared to direct laryngoscopy in our study (p<0.05). Mean POGO score was comparable in both the groups with statistically non- significant difference (p>0.05). Mean heart rate in Group DL was significantly less as compared to Group VL after intubation 0, 5, 10, 15, 30 minutes as well as up to post operatively 30 minutes. SBP, DBP, MAP and SPO2 were comparable in both the groups with no significant difference.

Thus, video laryngoscope is a superior device than the conventional direct laryngoscope (Macintosh). It can be used as a teaching tool for novice intubators and offers approach to tracheal intubation.

Conflict of Interest: None to declare

Source of funding: Nil

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