European Journal of Cardiovascular Medicine

Laryngoscopy and endotracheal intubation are essential components of general anesthesia administration, especially in laparoscopic surgeries. However, these procedures are associated with a significant sympathetic stress response characterized by tachycardia, hypertension, and elevated catecholamine levels, which may be detrimental, particularly in patients with cardiovascular compromise [1,2]. This hemodynamic surge results from stimulation of the laryngeal and tracheal mucosa and can persist for several minutes post-intubation [3].

Various pharmacological agents have been used to attenuate the stress response, including opioids, beta-blockers, calcium channel blockers, and alpha-2 adrenergic agonists [4]. Among these, dexmedetomidine, a selective alpha-2 adrenergic receptor agonist, has gained popularity due to its anxiolytic, sedative, analgesic, and sympatholytic properties without significant respiratory depression [5,6]. Its intranasal administration offers a non-invasive route, providing adequate sedation and attenuation of the pressor response during intubation [7].

Lignocaine, a local anesthetic with membrane-stabilizing properties, when administered topically, suppresses airway reflexes and provides local anesthesia to the mucosa, thereby mitigating the cardiovascular response to intubation [8,9]. Intranasal lignocaine spray has also been used to anesthetize the upper airway and improve patient comfort during instrumentation [10].

Although both intranasal dexmedetomidine and lignocaine have independently demonstrated efficacy in attenuating the pressor response to laryngoscopy, limited data exist comparing their combined use versus dexmedetomidine alone [11]. Laparoscopic surgeries further exacerbate the stress response due to pneumoperitoneum and Trendelenburg positioning, necessitating effective control of hemodynamic fluctuations [12].

This study aims to evaluate and compare the efficacy of intranasal dexmedetomidine combined with lignocaine spray versus intranasal dexmedetomidine alone in attenuating the stress response to laryngoscopy and intubation in patients undergoing elective laparoscopic surgeries.

Study Design and Setting

This was a prospective, randomized study conducted in the Department of Anesthesiology at Integral Institute of Medical Sciences and Research, Lucknow, Uttar Pradesh. The study was carried out over a period of 18 months following approval from the Institutional Ethics Committee.

Study Population

A total of 120 adult patients, aged between 18 and 60 years, scheduled to undergo elective laparoscopic surgeries under general anesthesia, were enrolled in the study after obtaining written informed consent.

Inclusion Criteria

·         Age between 18–60 years

·         American Society of Anesthesiologists (ASA) physical status I and II

·         Mallampati class I or II

·         Patients undergoing elective laparoscopic surgeries under general anesthesia

Exclusion Criteria

·         Refusal to participate in the study

·         Anticipated difficult airway

·         ASA grade III and IV

·         Known allergy to study drugs

·         History of nasal surgery, nasal trauma, or nasal polyps

·         Pregnant patients

Sample Size Calculation

The sample size was determined using the following parameters:

·         Power (1 - β) = 0.80

·         Zβ = 0.842

·         Type I error (α) = 0.05

·         Zα/2 = 1.96

·         Standard deviation (SD) = 0.77 (based on previous study)

·         Expected mean difference in SpO₂ = 0.4

Based on these values, a minimum of 60 patients per group was required, yielding a total sample size of 120.

Randomization and Group Allocation

Patients were randomly assigned to one of two groups using a computer-generated randomization table:

·         Group DL (n = 60): Received intranasal dexmedetomidine 1 mcg/kg diluted with normal saline to a total volume of 2 mL, administered as nasal drops using a needleless syringe. Thirty minutes later, 10% lignocaine spray was administered—two puffs each (0.1 mL = 10 mg per puff) to the more patent nostril, tonsillar pillars, posterior tongue, and posterior pharyngeal wall.

·         Group D (n = 60): Received intranasal dexmedetomidine 2 mcg/kg diluted with normal saline to a total volume of 2 mL, administered in a similar fashion. Normal saline spray was used as placebo at the same time points as lignocaine in Group DL.

Preoperative Assessment and Procedure

All patients underwent a routine pre-anesthetic evaluation, including detailed medical history, general physical examination, and standard laboratory investigations. After informed consent, eligible patients were prepared in the preoperative area. Baseline hemodynamic parameters—heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and peripheral oxygen saturation (SpO₂)—were recorded.

Study drugs were administered 30 minutes prior to the induction of anesthesia. Patients were then shifted to the operating room. Hemodynamic parameters were recorded at the following time points:

·         Baseline (before drug administration)

·         Before induction

·         Immediately after intubation (0 min)

·         At 1 minute, 3 minutes, 5 minutes, and 10 minutes post-intubation

Statistical Analysis

Data were entered in Microsoft Excel and analyzed using SPSS version 26.0 (IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation (SD) and compared using Analysis of Variance (ANOVA). Categorical variables were expressed as frequency (percentage) and analyzed using the Chi-square test. A p-value < 0.05 was considered statistically significant.

Table 1: Descriptive Statistics for Age of Study Participants

Table 1 presents the descriptive statistics for the age of study participants. The mean age is 40.11 years, with a standard deviation of 7.96, indicating moderate variability. The median age is 40.00 years, showing a central tendency close to the mean. The age range spans from 25 to 57 years, with 120 valid observations.

Table 2: Distribution of Study Participants by Sex

Table 3: Distribution of Study Participants by Group

Table 4: Age-wise Distribution of Participants across Groups D and DL

Table 5: Sex-wise Distribution of Participants across Groups D and DL

Table 6: Comparison of Heart Rate (HR) Between Groups D and DL at Various Time Intervals

Table 6 compares heart rate (HR) between Groups D and DL at various time intervals. At baseline and preinduction, Group D had significantly lower HR than Group DL (p < 0.05). After intubation, Group D continued to show a lower HR, with significant differences observed at 5 and 10 minutes after intubation (p < 0.001). No significant differences were found at other time points.

Table 7: Comparison of Systolic Blood Pressure (SBP) Between Groups D and DL at Various Time Intervals

Table 7 compares the systolic blood pressure (SBP) between Groups D and DL at different time intervals. At baseline and preinduction, Group DL had significantly higher SBP compared to Group D (p < 0.05). However, after intubation, there were no significant differences in SBP between the two groups (p > 0.05) at subsequent time points, indicating similar blood pressure responses post-intubation.

Table 8: Comparison of Diastolic Blood Pressure (DBP) Between Groups D and DL at Various Time Intervals

Table 8 compares diastolic blood pressure (DBP) between Groups D and DL at various time intervals. At baseline and preinduction, Group D had significantly higher DBP than Group DL (p < 0.05). After intubation, DBP was lower in Group DL at all subsequent time points, with significant differences observed at 1 minute, 3 minutes, 5 minutes, and 10 minutes after intubation (p < 0.001).

Laryngoscopy and endotracheal intubation are potent noxious stimuli that result in sympathetic nervous system activation, leading to transient but significant increases in heart rate and blood pressure [1]. This stress response is particularly concerning in laparoscopic surgeries where pneumoperitoneum and patient positioning further challenge cardiovascular stability [2]. Thus, preemptive pharmacological attenuation of this response is essential to reduce perioperative complications.

In our study, we evaluated the efficacy of intranasal dexmedetomidine (Group D) versus intranasal dexmedetomidine combined with lignocaine spray (Group DL) in attenuating the hemodynamic response to laryngoscopy and intubation. Our findings suggest that the combination therapy provided better blunting of sympathetic responses as compared to dexmedetomidine alone.

Heart Rate Response

Group DL showed a significantly lower heart rate at 5 and 10 minutes after intubation compared to Group D (p < 0.001), indicating superior suppression of the tachycardic response. Dexmedetomidine, a highly selective α2-adrenoceptor agonist, decreases central sympathetic outflow and enhances vagal activity, leading to bradycardia and hypotension [3]. Additionally, lignocaine acts as a local anesthetic by blocking sodium channels, preventing afferent sensory transmission from the upper airway mucosa, thus blunting reflex sympathetic discharge [4]. Previous studies have also shown that topical lignocaine decreases the incidence of tachycardia during intubation [5].

Blood Pressure Response

Our results demonstrated that Group DL had significantly lower diastolic blood pressure (DBP) values from 1 to 10 minutes post-intubation. The systolic blood pressure (SBP) was also better controlled in Group DL at baseline and pre-induction, though the rise post-intubation was comparable. The enhanced attenuation in Group DL can be attributed to the synergistic effects of dexmedetomidine’s central sympatholysis and lignocaine’s peripheral desensitization. This aligns with findings from Kumari et al. who demonstrated better BP control with combined use of alpha-2 agonists and local anesthetics [6].

Dexmedetomidine’s reduction of plasma catecholamines is well-documented and contributes significantly to hemodynamic stability [7]. Lignocaine spray, particularly in the oropharyngeal and laryngeal region, blunts baroreceptor-mediated hypertensive responses during laryngoscopy [8].

Mean Arterial Pressure (MAP)

Although MAP values were not numerically tabulated, graphical representations indicate more stable MAP trends in Group DL. This is consistent with studies by Scheinin et al., who showed that dexmedetomidine stabilizes MAP through central and peripheral adrenergic modulation [9].

Oxygen Saturation (SpO₂)

SpO₂ remained stable and comparable across both groups, indicating that neither intranasal dexmedetomidine nor lignocaine spray had any adverse respiratory effects. This supports the safe use of dexmedetomidine as a non-invasive premedication, as observed in studies by Goyal et al. [10].

Route of Administration

The intranasal route offers a needle-free, patient-friendly alternative for sedation and anxiolysis. It ensures rapid absorption via the rich vascular plexus in the nasal mucosa, bypassing first-pass hepatic metabolism. Studies by Iirola et al. confirm that intranasal dexmedetomidine achieves adequate plasma levels and sedation within 20–40 minutes [11].

Clinical Implications

The combined use of intranasal dexmedetomidine and lignocaine spray effectively attenuated the cardiovascular responses to laryngoscopy and intubation in laparoscopic procedures. This multimodal approach is beneficial in patients with cardiovascular comorbidities or high anesthetic risk, as it reduces the need for high doses of systemic agents and enhances intraoperative stability [12].

The present study demonstrates that the combination of intranasal dexmedetomidine and lignocaine spray (Group DL) is more effective than intranasal dexmedetomidine alone (Group D) in attenuating the hemodynamic responses to laryngoscopy and endotracheal intubation in patients undergoing laparoscopic surgery. The synergistic effect of dexmedetomidine’s central sympatholytic action and lignocaine’s peripheral desensitization results in better control of heart rate and blood pressure during the peri-intubation period, without compromising oxygen saturation or causing adverse effects.

Given its non-invasive route, favorable safety profile, and improved hemodynamic stability, the combined use of intranasal dexmedetomidine and lignocaine spray may be recommended as a simple and effective premedication strategy, especially in patients at risk of exaggerated cardiovascular responses.

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