Hemodynamic Responses of Different Laryngoscopes

During laryngoscopy and endotracheal intubation, stimulation of supraglottic regions leads to an increase in the plasma catecholamine concentrations due to the activation of the sympatho-adrenal system. Prevention or reduction of this increment is important for hemodynamic control. Therefore, various methods such as providing adequate depth of anesthesia and shortening the time of laryngoscopy were used. On the other hand; alternative laryngoscopy devices and methods have recently started to be used.

In this randomized single blind study, our aim is to compare the hemodynamic responses of four different laryngoscopy techniques with Macintosh laryngoscope, McCoy laryngoscope, C-Mac videolaryngoscope and McGrath videolaryngoscope in patients with normal predictive airway.

After obtaining Institutional Ethics Committee approval and patient consents, 170 patients (18-65 years old) with ASA I-II status requiring general anesthesia with endotracheal intubation, were enrolled to this prospective randomized study.

Besides routine monitorization (noninvasive blood pressure (NIBP), electrocardiography (ECG), heart rate (HR), peripheral oxygen saturation (SPO2)), continuous BIS monitorization was also performed. Sedation was performed using a standard dose of IV fentanyl (1.5 μg/kg) and midazolam (0.05 mg/kg). Baseline systolic, diastolic and mean arterial blood pressures, HR and SPO2 values were recorded as T0. After a stabilization period of 10 minutes, propofol 2-3 mg/kg IV bolus was applied incrementally until a clinically desirable sedation level was achieved. If necessary, additional propofol boluses were given to maintain a BIS level of 60. As soon as BIS level was reduced to 60, patients were put on 0.6 mg/kg IV rocuronium. 100% oxygen was applied with a facemask for a period of 3 minutes. Then, post induction values (T1) were recorded.

One hundred seventy patients were randomly allocated equally to Macintosh laryngoscope, Mc-Coy laryngoscope, C-Mac videolaryngoscope and McGrath videolaryngoscope groups. Endotracheal tube (ETT) of 7.0 mm and 7.5 mm were placed to female and male patients, respectively. All intubation procedures were performed by a single experienced anesthesiologist. Intubation stylet was provided, if necessary. Cuff pressures of endotracheal tubes were standartized to 30 cmH2O via a manometer. The following measurements were recorded immediately after intubation (T2) and at one minute intervals for 5 minutes (T3, T4, T5, T6 and T7).

Moreover; the number of intubation attempts, stylet needs, Cormack-Lehane scales, and the complications occurred during intubation procedures were recorded as the second outcomes. Patients were also questioned for possible sore throat at postoperative 2 hours. Patients requiring more than one attempt to achieve successful intubation were excluded from statistical analysis of data.

Inclusion criteria

• Patients with ASA I-II status, requiring general anesthesia with endotracheal intubation

Exclusion criteria

• ASA status higher than II, a history or suspected of difficult airway, hypertansion, under treatment known to affect blood pressure or heart rate (Beta blocker/ Ca-channel blocker), BIS value > 60