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Year : 2018 | Volume : 6 | Issue : 1 | Page : 31 - 36  


Original Articles
Attenuation of hemodynamic response to laryngoscopy and intubation-The Effect of Diltiazem, A randomized controlled study

Swathi Appagalla1, Manjula V Ramsali2, Sarada Devi Vankayalapati3, Surender Pasupuleti 4

1Assistant professor, 2Assistant professor, 3Assistant professor, 4 Professor and HOD, Department of Anesthesia, Malla Reddy Medical college for women, Hyderabad

Corresponding Author

Email: manjularamsali@gmail.com

 

Abstract:

Background:  Direct laryngoscopy and tracheal intubation following induction of anesthesia is almost always associated with hemodynamic changes due to reflex sympatho-adrenal activity which may result in hypertension, tachycardia and arrhythmias. Various agents like lidocaine, opioids, esmolol, magnesium sulphate, alpha 2 agonists and propofol have been shown to attenuate these responses, but they have limitations and side effects. Recently several studies have shown that calcium channel antagonist Diltiazem   with its direct vasodilation, direct negative chronotropic and dromotropic properties is effective. Our study was designed to determine the efficacy of diltiazem 0.3mg/kg in attenuating the hemodynamic response to laryngoscopy and intubation in ASA I & II patients.

Objectives: The prospective randomized study was done to evaluate the efficacy of Diltiazem   in attenuation of hemodynamic response to laryngoscopy and intubation.

Methods: 50 patients aged between 22-55 yrs of either sex of ASA Grade I and II scheduled for elective surgeries were studied after randomization into two groups, Control and Study (Diltiazem) groups.  The anesthesia technique was standardized for both the groups.  All the patients were given either saline 2ml or diltiazem 0.3 mg/kg in 2ml 60 seconds before laryngoscopy and intubation. The parameters like HR, SBP, DBP, and MAP were recorded at pre-induction, at induction, during laryngoscopy and intubation and at 1min, 2min, 3min, and 5min after intubation. Patients were also observed for side effects like hypotension, bradycardia and bronchospasm.

Results: There was increase in the HR, SBP, DBP and MAP after induction and immediately after laryngoscopy and intubation in the control group but there was a fall in SBP, DBP and MAP in study group. There was no significant change in HR in the study group.

Conclusion: Our study concludes that diltiazem 0.3 mg/kg given IV 60 seconds before laryngoscopy and intubation can be safely employed to attenuate hemodynamic responses without any side effects.

Key words: Cardiovascular response, endotracheal intubation, diltiazem, laryngoscopy

Introduction:

Direct laryngoscopy and endotracheal intubation following induction of anesthesia is almost always associated with hemodynamic changes due to reflex sympathetic discharge caused by epipharyngeal and laryngopharyngeal stimulation. 1, 2 This increased sympatho-adrenal activity may result in hypertension, tachycardia and arrhythmias. 3, 4 These changes are the result of increase in catecholamine activity and are usually transitory, variable and unpredictable. Hypertensive patients are more prone to have significant increases in blood pressure whether they have been treated beforehand or not. 5 Transitory hypertension and tachycardia are probably of no consequence in healthy individuals but either or both may be hazardous to those with hypertension, myocardial insufficiency or cerebrovascular diseases. This laryngoscopic reaction in such individuals may predispose to development of pulmonary edema, 6 myocardial insufficiency7 and cerebrovascular accident. 7-8

Many pharmacological and non-pharmacological methods have been devised to reduce the extent of hemodynamic events like high dose of opioids, 9 local anesthetics (lignocaine), 10 alpha and beta adrenergic blockers, 11 vasodilators (nitroglycerine) and minimizing the duration of laryngoscopy to less than 15 seconds. 12 Lignocaine   is used in many ways but very popular is application of the drug topically to the larynx and trachea. 13 Intravenous lignocaine has central depressant and anti-arrhythmic effect and   was found to be a more suitable alternate method to minimize this pressor response. 14, 15 Several studies have shown that calcium channel antagonist Diltiazem has direct vasodilation and direct negative chronotropic and dromotropic properties so effective in reducing the pressor response. 5, 16

The present study was undertaken to determine the effect of IV Diltiazem 0.3mg/kg in attenuating the hemodynamic response to laryngoscopy and intubation in ASA I and II patients coming for elective surgeries.

Material and Methods:

After the Institutional Ethics Committee approval and written informed consent, the present study was carried out on fifty adult patients of either sex, aged between 20 – 65 years, scheduled for various procedures undergoing elective surgery under general anesthesia in ASA grade I/II physical status in the department of anesthesia at MRMCW, Hyderabad from March 2015 to December 2016

Patients suffering from cardiovascular, Respiratory, Cerebrovascular diseases, Diabetes, Hypertension and predicted difficult intubation were excluded from the study. Pre-anesthetic check up was conducted and a complete physical examination was done. Routine investigations like CBP, blood group & typing, Blood Urea, Serum creatinine, BT, CT, Blood sugar, ECG and CXR were done. Patients were randomly divided into two groups of 25 each. Randomization was done by computer generated table.

Group I- Control Group—received 2 ml of Normal Saline IV 60 sec before laryngoscopy & intubation.

Group II- Diltiazem Group—received 0.3 mg/kg of Diltiazem IV 60 sec before laryngoscopy & intubation.

The premedication, induction agent & muscle relaxant agents used for anesthesia technique were standardized for both the groups. In the OR, patients were connected to the standard monitoring like ECG, NIBP & Spo2 prior to induction of anesthesia.  After securing wide bore IV line, patients were given glycopyrrolate 0.2mg, ondan 4mg, midazolam 1mg and fentanyl 2µg/kg.  Preoxygenated with 100 % O2 for 3 min induced with Propofol 2mg /kg, vecuronium 0.1mg/kg and lungs were ventilated with O2 & N2O for 3 min. Patients received either NS or Diltiazem (0.3mg/kg) 60 sec before laryngoscopy and intubation.  Intubation was achieved with an appropriate sized oral cuffed portex endotracheal tube by the aid of macintosh laryngoscope blade. Anesthesia was maintained with O2 & N2O, isoflurane and vecuronium with controlled ventilation. At the end of surgery neuromuscular blocked was reversed with neostigmine 2.5 mg & glycopyrrolate 0.4 mg IV. All the patients were followed up in the post operative period and observed for any adverse effects. The anesthesiologist performing the study was blinded to the study drugs. The drug preparation and administration was done by senior anesthesiologist and observations are done by another anesthesiologist who is unaware of the drug administered.

HR, SBP, DBP, MAP, ECG and SpO2 were monitored continuously.  Blood pressure (SBP, DBP, MAP) & Heart Rate (HR)   parameters were recorded at pre-induction, after induction, during laryngoscopy and intubation and at 1min, 2min, 3 min and 5 min after intubation. We also observed for any side effects like hypotension, bradycardia, bronchospasm etc.

   The parameters were recorded and data were entered into statistical package for social sciences (SPSS-20). Statistical analysis were done using unpaired t test between two groups and paired t test for  inter group comparison through graph pad software with quick cals.

Results:

Table 1: Demographic profile

Description

Control group mean+SD

Study group mean+SD

Age in years

36.64±6.87

35.92±9.53

Weight  in KG

58±5

55±5.8

Male : Female

12:13

9:16

ASA grade I/II

17/8

18/7

MP grade 1/II

19/6

20/5

 

Patients in both the groups were comparable for age, weight,  sex ratio and ASA physical status and were not statistically significant. (Table 1)

Table 2: Heart rate Comparison

Time interval

Control group mean+SD

Study group mean+SD

P value

Remarks

Pre-Induction

87.36±9.89

91.1±10.8

 0.2059

NS

After Induction

96.52±8.95

98±13.1

0.6433

NS

During laryngoscopy & intubation

107±10.80

106±10.80

0.7448

NS

1 min

108±9.18

104±11

0.1694

NS

2 min

103.52±7.48

101±10.1

0.3612

NS

3 min

101.92±8.33

98.7±9.95

0.2676

NS

5 min

100.40±8.73

96±9.56

0.0959

NS

 

The above table (table 2) shows the comparison of HR in both the groups. The parameters indicate that the difference between the groups are not statistically significant (p>0.05). Pre-induction values are taken as basal values.

Graph 1: HR comparisons

 

Table 3: SBP Comparison

Time interval

Controlgroup

mean+SD

Study group

mean+SD

P value

Remarks

Pre-Induction

132.12±9.48

128.68±10.953

0.241

NS

After Induction

129.52±10.48

120.80±15.861

0.027

SS

During laryngoscopy & intubation

157.40±12.055

133.44±9.70

0.0001

ESS

1 min

157.08±11.56

130.52±12.248

0.0001

ESS

2 min

149.68±8.325

124.32±10.024

0.0001

ESS

3 min

143.28±10.710

119.2±9.552

0.0001

ESS

5 min

140.32±11.393

114.32±8.934

0.0001

ESS

Graph 2: SBP comparisons

 

The parameters within the group indicate that there was statistically significant rise in SBP in the control group as compared to basal value at the all times. Where as in study group there was transient rise in SBP only during and after 1 min of laryngoscopy and intubation which was not significant

When compared between the groups the  rise in SBP  in control group is statistically significant(p<0.05) during laryngoscopy, 1min, 2min, 3 min & 5min after laryngoscopy and intubation when compared to study group. Pre-induction values are taken as basal values which are not statistically significant (p>0.05).

Table 4: DBP Comparison

Time interval

Control group mean+SD

Study group mean+SD

P value

Remarks

Pre-Induction

81.84±8.350

79.00±8.216

0.0730

NS

After Induction

84.84±9.294

74.80±10.124

0.0027

VSS

During laryngoscopy & intubation

103.44±8.471

84.76±9.718

0.0001

ESS

1 min

105.36±9.214

82.16±11.025

0.0001

ESS

2 min

98.88±8.388

80.20±8.365

0.0001

ESS

3 min

97.48±7.912

78±6.93

0.0001

ESS

5 min

93.88±7.190

75.56±7.654

0.0001

ESS

 Graph 3: DBP comparison

There is a statistically significant rise in DBP in the control group as compared to basal value at the all times. Where as in study group there was transient rise in DBP only during laryngoscopy and after 1 & 2 min of laryngoscopy and intubation but was not significant. Pre-induction values are taken as basal values which are not statistically significant   (p > 0.05).

The inter group comparison of DBP  showed rise in DBP in control group at induction, during laryngoscopy and at 1, 2, 3 and 5 min after laryngoscopy and intubation to the control group which was statistically  significant(p<0.05).

Table 5: MAP Comparison

Time interval

Control group mean+SD

Study group mean+SD

P value

Remarks

Pre-Induction

98.80±8.655

92.72±7.586

0.111

NS

After Induction

98.20±9.147

90±9.819

0.0038

VSS

During laryngoscopy & intubation

120.84±9.603

100.72±8.925

0.0001

ESS

1 min

122.60±8.36

97.52±10.199

0.0001

ESS

2 min

115.76±8.04

94.72±8.218

0.0001

ESS

3 min

111.92±8.650

91.36±6.98

0.0001

ESS

5 min

108.48±7.95

88.84±6.938

0.0005

ESS

 

Graph 4: MAP comparison

 

There is statistically significant rise in MAP in the control group as compared to basal value at the all times. Where as in study group there was transient rise in MAP only during laryngoscopy, and at 1, 2 min of laryngoscopy and intubation which was not statistically significant

Pre-induction values are taken as basal values which are not statistically significant (p>0.05). The rise in MAP in control group is statistically significant (p<0.05) at induction, during laryngoscopy and at1, 2, 3, 5 min after laryngoscopy and intubation when compared to study group.

 

Discussion:

The introduction of general anesthesia made it possible to induce a state of controlled unconsciousness so that a patient is insensitive to pain and unaware of the events occurring during the surgical procedure. Traditional laryngoscopy and tracheal intubation is the mainstay in safeguarding the airway in such patients.  Although intubation has its own advantages such as safe secured airway, prevention of aspiration and delivery of anesthetic gases but it is not without complications.

Laryngoscopy and tracheal intubation may provoke a transient but marked sympathetic and sympathoadrenal response manifesting as tachycardia, hypertension and arrhythmias. 3, 4 The haemodynamic changes brought about by laryngoscopy and tracheal intubation was first discovered by Reid and Brace. 18 But later Burstein et al 19 found the pressor response was due to augmented sympathetic response provoked by stimulation of epipharynx and laryngopharynx. These factors were further confirmed by Prys-Roberts. 4

These pressor responses are transient, variable and may not be of much significance in normal healthy patients. But in patients with co-morbidities, these transient changes can result in potentially deleterious effects like ventricular dysarrhythmias 4, left ventricular failure, 6 pulmonary edema, 6 myocardial ischemia 7 and cerebral hemorrhage. 8 These responses need to be attenuated as far as possible. Various pharmacological and mechanical modalities have been used to attenuate these responses but have their own limitations. Opioids were found to be effective but caused respiratory depression, chest wall rigidity and prolonged recovery time.                                                                                                                                                                                                                                                                                                                                                 Devault et al 20 employed   adrenergic blockers and Robert K Stoelting 23 used direct acting vasodilators to attenuate the hemodynamic pressor response to laryngoscopy and   tracheal intubation. The disadvantage of using Beta blockers was long duration of action causing intraoperative hypotension whereas vasodilators caused reflex tachycardia and also required the need for invasive arterial BP monitoring.  

Diltiazem is a calcium channel blocker with rapid onset and short duration of action. It is effective in attenuating the increase in pulse rate and BP following laryngoscopy and tracheal intubation. This is due to its vasodilatory and negative chronotropic and dromotropic effects.  

The present study was under taken to know the severity, duration of hemodynamic responses to laryngoscopy and intubation and to observe the efficacy of Diltiazem in blunting hemodynamic responses.

The study was conducted in 50 patients of two groups of 25 each.  Group I served as control group and received normal saline 2 ml IV where as Group II served as study group and received Diltiazem 0.3 mg/kg IV  60 sec before intubation in identical syringe. General anesthesia technique was standardized for both the groups. 

Both the groups were comparable for demographic data. The pre-induction values were taken as base line values.   Our results showed that there was an increase in HR after induction and immediately after laryngoscopy and intubation in both the groups, but these changes were not statistically significant. SBP, DBP and MAP increased during laryngoscopy and at 1, 2, 3, & 5 min after laryngoscopy and intubation in control group, where as in the study group there was minimal increase in SBP, DBP and MAP only during laryngoscopy and 1 min after laryngoscopy and intubation which returned to baseline by 2 min.

Three calcium channel blockers were compared in normotensive patients by Mikawa et al 16 as regard to their effect on pressor response. In their study, verapamil completely blunted the increase in BP due to laryngoscopy and intubation and produced   mild hypotension 5min after induction. Nicardipine blunted the BP rise but produced tachycardia, while verapamil could effectively blunt tachycardia. Attempts to attenuate these hemodynamic responses have been partially successful. As IV form of Diltiazem is easily available now days, we studied the hemodynamic responses to laryngoscopy and intubation.

IV Diltiazem was administered 60 sec (1 min) before the start of laryngoscopy in our study and was planned in such a way that   the effect of Diltiazem in lowering BP coincided with the hemodynamic responses to laryngoscopy. This fact is essentially based on the study reports of Mikawa et al 21 and Stoelting. 10

There was   a slight increase in HR and decrease in BP (SBP, DBP and MAP) with induction of anesthesia in our study group. This can be explained by the fact that propofol can cause myocardial depressant and peripheral vasodilatation leading to hypotension and tachycardia.  The rise in HR was 10.5% in control group and 7.57% in Diltiazem group. This co-relates with the study reports of Millar Forbe et al 9 and Mikawa et al. 21.

HR was increased in both the groups and the difference was not significant statistically. SBP rise was highest in the control group as compared to the study group during laryngoscopy and intubation. These observations were in concurrence with the study reports of Mikawa et al 21 and Hasegawa et al. 22   Similarly Mohan et al 24 and Medha Sangawar et al 25 in their study concluded that Diltiazem was useful in attenuation of blood pressure response but not effective in preventing tachycardia.  Mean SBP rise was 19.4% vs. 1.36% during laryngoscopy and intubation and at 1 min following intubation in the control vs. Diltiazem group. This was extremely significant statistically. Values returned to the baseline by 2 min in the study group whereas in control group even at 5 minutes values were high.  Same with MAP, the values were 22.3% vs. 8.6% in control vs. Diltiazem group respectively during laryngoscopy and intubation and at 1min following intubation.   DBP and MAP values returned to base line in 2 min in the Diltiazem group but in control group the readings were high even at 5 min.

In our study, the side effects and complications were very few. We noticed hypotension in 2 patients in the study group which improved with IV fluids and did not require pharmacological intervention.

Conclusion:

Diltiazem- a calcium channel blocker in the dose of 0.3mg/ kg IV given 60sec before laryngoscopy attenuates the hemodynamic response to laryngoscopy and intubation. The effects of Diltiazem are more significant on the blood pressure changes than heart rate. Hence we conclude that single bolus dose of Diltiazem 0.3 mg/kg IV given 60 sec before laryngoscopy can be safely employed to attenuate hemodynamic responses without any side effects.

 

References:

 

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