Comparison of bolus and continuous infusion of esmolol on hemodynamic response to laryngoscopy, endotracheal intubation and sternotomy in coronary artery bypass graft

Abstracts

BACKGROUND AND OBJECTIVE:

The aim of this randomized, prospective and double blinded study is to investigate effects of different esmolol use on hemodynamic response of laryngoscopy, endotracheal intubation and sternotomy in coronary artery bypass graft surgery.

METHODS:

After approval of local ethics committee and patients' written informed consent, 45 patients were randomized into three groups equally. In Infusion Group; from 10 min before intubation up to 5th minute after sternotomy, 0.5 mg/kg/min esmolol infusion, in Bolus Group; 2 min before intubation and sternotomy 1.5 mg/kg esmolol IV bolus and in Control Group; %0.9 NaCl was administered. All demographic parameters were recorded. Heart rate and blood pressure were recorded before infusion up to anesthesia induction in every minute, during endotracheal intubation, every minute for 10 minutes after endotracheal intubation and before, during and after sternotomy at first and fifth minutes.

RESULTS:

While area under curve (AUC) (SAP × time) was being found more in Group B and C than Group I, AUC (SAP × T _int and T _st) and AUC (SAP × T₂) was found more in Group B and C than Group I (p < 0.05). Moreover AUC (HR × T _st) was found less in Group B than Group C but no significant difference was found between Group B and Group I.

CONCLUSION:

This study highlights that esmolol infusion is more effective than esmolol bolus administration on controlling systolic arterial pressure during endotracheal intubation and sternotomy in CABG surgery.

Esmolol; Laryngoscopy; Endotracheal intubation; Sternotomy hemodynamics; Coronary artery; Bypass graft surgery

JUSTIFICATIVA E OBJETIVO:

o objetivo deste estudo prospectivo, randômico e duplo-cego foi investigar os efeitos do uso diferente de esmolol na resposta hemodinâmica à laringoscopia, intubação orotraqueal e esternotomia em cirurgia de revascularização coronária.

MÉTODOS:

após obter a aprovação do Comitê de Ética local e consentimento informado assinado pelos pacientes, 45 pacientes foram randomicamente divididos em três grupos. O Grupo I (infusão) recebeu 0,5 mg/kg/min de esmolol em infusão a partir de 10 min antes da intubação até 5 minutos após a esternotomia; o Brupo B (bolus) recebeu 1,5 mg/kg de esmolol em bolus IV a partir de 2 min antes da intubação e esternotomia; o grupo C (controle) recebeu NaCl a 0,9%. Todos os parâmetros demográficos foram registados. Os valores de frequência cardíaca e pressão arterial foram registrados desde antes da infusão até a indução da anestesia a cada minuto, durante a intubação endotraqueal, a cada minuto durante 10 min após a intubação endotraqueal e antes, durante e após a esternotomia no primeiro e quinto minutos.

RESULTADOS:

enquanto a área sob a curva (ASC) (SAP × tempo) foi maior nos grupos B e C que no Grupo I, a ASC (SAP × T _int e T _st) e ASC (SAP × T2) foram maiores nos grupos B e C que no Grupo I (p < 0,05). Além disso, a ASC (FC × T _st)) foi menor no Grupo B que no Grupo C, mas não houve diferença significante entre os grupos B e I.

CONCLUSÃO:

este estudo destaca que a administração de esmolol em infusão é mais eficaz que em bolus para controlar a pressão arterial sistólica durante a intubação endotraqueal e esternotomia em CRC.

Esmolol; Laringoscopia; Intubação endotraqueal; Hemodinâmica em esternotomia; Artéria coronária; Cirurgia de revascularização

JUSTIFICACIÓN Y OBJETIVO:

el objetivo de este estudio prospectivo, aleatorizado y doble ciego fue investigar los efectos del diferente uso del esmolol en la respuesta hemodinámica a la laringoscopia, intubación orotraqueal y esternotomía en cirugía de revascularización coronaria.

MÉTODOS:

después de obtener la aprobación del Comité de Ética local y el consentimiento informado firmado por los pacientes, 45 de ellos fueron aleatoriamente divididos en 3 grupos. El grupo I (infusión) recibió 0,5 mg/kg/min de esmolol en infusión desde 10 min antes de la intubación hasta 5 min después de la esternotomía; el grupo B (bolo), que recibió 1,5 mg/kg de esmolol en bolo iv a partir de 2 min antes de la intubación y esternotomía; el grupo C (control) recibió NaCl al 0,9%. Todos los parámetros demográficos fueron registrados. Los valores de frecuencia cardíaca y presión arterial fueron registrados ya antes de la infusión y hasta la inducción de la anestesia cada minuto durante la intubación endotraqueal, cada minuto durante 10 min después de la intubación endotraqueal, y antes, durante y después de la esternotomía en el primer y quinto minutos.

RESULTADOS:

mientras que el área bajo la curva (AUC) (presión arterial sistólica [PAS] × tiempo) fue mayor en los grupos B y C que en el grupo I, el AUC (PAS ×T _int y T _st) y AUC (PAS × T ₂) fueron mayores en los grupos B y C que en el grupo I (p < 0,05). Además, el AUC (frecuencia cardíaca × T _st) fue menor en el grupo B que en el grupo C, pero no hubo diferencia significativa entre los grupos B e I.

CONCLUSIÓN:

este estudio destaca que la administración del esmolol en infusión es más eficaz que en bolos para controlar la PAS durante la intubación endotraqueal y la esternotomía en cirugía de revascularización coronaria.

Esmolol; Laringoscopia; Intubación endotraqueal; Hemodinámica en esternotomía; Arteria coronaria; Cirugía de revascularización

Introduction

Patients undergoing coronary artery bypass graft (CABG) surgery are at risk for perioperative myocardial ischemia. Tachycardia as a predictor for increased myocardial oxygen consumption which doubles the incidence of myocardial ischemia. During the operative procedure for coronary revascularization, some maneuvers, such as intubation, sternotomy and mediastinal preparation, may be associated with tachycardia and increases in blood pressure despite the adequate level of anesthesia.¹

Some drugs (IV opioids, vasodilators, calcium channel and β-blockers) are available for the clinicians to control the hemodynamic response to laryngoscopy and intubation.² β-adrenoceptor blockers were shown to decrease the incidence of postoperative myocardial ischemia.³

Esmolol (metil-3[4-(2-hidroxy-3[izopropylamino]propxy)fenyl] is a specific cardioselective beta 1-blocker and it is hydrosoluble, without intrinsic sympathetic activity or membrane stabilizing activity at therapeutic dosages. Distribution and elimination half-life is 2 and 9 min, respectively. Esmolol is hydrolyzed by the blood esterases and a suitable agent for the perioperative period.⁴

Esmolol as a bolus or infusion was shown to prevent tachycardia and hypertension during laryngoscopy and intubation in a meta-analysis and previous studies.^{5 , 6 and 7}

So far, esmolol bolus and infusion administration has not been previously compared in cardiac patients. The purpose of this randomized, prospective, double blinded study, was to evaluate the effect of 1.5 mg/kg esmolol bolus and 0.5 mg/kg/min esmolol infusion on hemodynamic response of laryngoscopy, endotracheal intubation and sternotomy in coronary artery bypass graft (CABG) surgery.

Methods

Forty five patients, aging between 18 and 80 years, ejection fraction >40%, in ASA II-IV status, scheduled for elective CABG surgery, between February and April 2006, in Ankara University Medical Faculty were enrolled to the study after obtaining approval from the Local Research Ethics Committee and written informed consent. Patients with asthma, first-degree atrioventricular block, heart rate <50 beats/min, acute myocardial infarction, Mallampati score more than two and under β-blocker treatment or contraindicated for β-blocker agent were excluded from the study.

One hour before the operation, patients were premedicated with 2.5 mg diazepam and 50 mg dolantine IM. Preoperative medical treatments were continued till the morning of the operation. Patients' age, gender, weight, height, chronic diseases and medications were recorded as demographic parameters. Upon their arrival to the operating room patients were monitored by pulse oximetry, electrocardiogram and non-invasive arterial blood pressure. An intravenous line was inserted with 18 gauge catheter and % 0.9 NaCl infusion was started, 0.04 mg/kg midazolam IV was administered. For invasive blood pressure monitorization, an intraarterial catheter was inserted into the left radial artery after local anesthetic infiltration. Sixty seconds after induction of general anesthesia with 0.3 mg/kg ethomidate, 5 μg/kg fentanyl vs. 0.1 mg/kg vecuronium patients were intubated by the same clinician who were blind to the study drugs. Anesthesia was maintained with 3 μg/kg fentanyl and 0.01 mg/kg midazolam IV bolus injection every 30 min. Patients were ventilated to normocapnie with 50% air-oxygen in approximately 0.5 MAC isoflurane. 0.03 mg/kg vecuronium IV was administered as needed. Patients were randomly assigned according to computer-generated random number sequence into one of three groups. In Infusion Group (Group I); 0.5 mg/kg/min esmolol infusion was started 10 min before the endotracheal intubation up to 5th minute after sternotomy, and 2 min before both intubation and sternotomy %0.9 NaCl was administered, in Bolus Group (Group B); 2 min before both endotracheal intubation and sternotomy 1.5 mg/kg esmolol bolus IV and from 10 min before endotracheal intubation up to 5th minute after sternotomy %0.9 NaCl was administered and in Control Group (Group C); %0.9 NaCl infusion and bolus was administered instead of esmolol. Heart rate (HR) and systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) were recorded before infusion (baseline) up to anesthesia induction, during and soon after anesthesia induction, during endotracheal intubation, every minute for 10 min after endotracheal intubation and before, during and at first and fifth minutes after sternotomy. All demographic parameters were recorded.

SPSS 10.0 for Windows (SPSS Inc, Chicago, IL, USA) was used for all data analyses. For α = 0.05 and β = 0.20, sample size was calculated 15 subjects for each groups. ANOVA and Chi-square tests were used for analysis of demographic variables. Area under curve (AUC) (heart rate, systolic, diastolic and mean arterial pressure x time) was calculated and compared with one-way ANOVA test between groups. A p value of <0.05 was considered statistically significant.

Results

No significant difference was found between groups according to demographic parameters (Table 1).

Table 1
Demographic data of groups.

	Group I (n = 15)	Group B (n = 15)	Group C (n = 15)	p
Age (years)	61 ± 6	63 ± 7	64 ± 7	NS
Gender (M/F)	10/5	11/4	10/5	NS
Weight (kg)	84 ± 12	87 ± 10	81 ± 15	NS
Height (cm)	171 ± 6	175 ± 8	172 ± 9	NS
ASA Classification (I/II/III/IV)	0/1/14/0	0/2/13/0	0/3/12/0	NS
Chronic Disease (±)	15/0	15/0	15/0	NS
Medication (±)	15/0	15/0	15/0	NS

• Data is presented as mean ± SD.
• ^{Group I}
  : Esmolol infusion group
• ^{Group B}
  : Esmolol bolus group
• ^{Group C}
  : Control group
• ^NS
  : Statistically not significant

AUC (heart rate, systolic, diastolic and mean arterial pressure × time) between groups were compared and according to Table 2, Group I was significantly more effective than other two groups in controlling systolic arterial pressure (SAP) but no significant difference on other parameters was found.

Table 2
Area under curve (AUC) of groups. (HR, SAP, DAP and MAP × T).

	Group I (n = 15)	Group B (n = 15)	Group C (n = 15)
HR × TIME (cm2)	1729 ± 208	1893 ± 304	1973 ± 304
SAP × TIME (cm2)	2843 ± 360*	3297 ± 548	3151 ± 397
DAP × TIME (cm2)	1635 ± 364	1767 ± 348	1650 ± 304
MAP × TIME (cm2)	2189 ± 366	2404 ± 399	2225 ± 293

• Data is presented as mean ± SD.
• ^HR
  , heart rate
• ^SAP
  , systolic arterial pressure
• ^DAP
  , diastolic arterial pressure
• ^MAP
  , mean arterial pressure
• ^T
  , time
• ^{Group I}
  , Esmolol infusion group
• ^{Group B}
  , Esmolol bolus group
• ^{Group C}
  , control group
• ^*
  p < 0.05 compared with Group B and C.

AUC (heart rate, systolic, diastolic and mean arterial pressure × T ₁ (time between the beginning of infusion and the beginning of anesthesia induction) and T₂ (time between the beginning of anesthesia induction and the 5th minute after sternotomy)) were compared. According to Table 3 infusion group was significantly more effective than other two groups in controlling SAP after induction but no significant difference was observed on other parameters.

Table 3
Area under curve (AUC) of groups. (HR, SAP, DAP and MAP × T1 and T2).

	Group I (n = 15)	Group B (n = 15)	Group C (n = 15)
HR × T1 (cm2)	743 ± 91	861 ± 167	835 ± 153
HR × T2 (cm2)	986 ± 136	1032 ± 150	1136 ± 224
SAP × T1 (cm2)	1329 ± 215	1456 ± 298	1408 ± 252
SAP × T2 (cm2)	1514 ± 193*	1840 ± 299	1743 ± 224
DAP × T1 (cm2)	661 ± 143	706 ± 161	669 ± 113
DAP × T2 (cm2)	973 ± 275	1061 ± 223	981 ± 211
MAP × T1 (cm2)	989 ± 161	1070 ± 199	973 ± 146
MAP × T2 (cm2)	1200 ± 265	1334 ± 259	1251 ± 191

• Data is presented as mean ± SD.
• ^HR
  , heart rate
• ^SAP
  , systolic arterial pressure
• ^DAP
  , diastolic arterial pressure
• ^MAP
  , mean arterial pressure
• ^T1
  , time between the beginning of infusion and the beginning of anesthesia induction
• ^T2
  , time between the beginning of anesthesia induction and the 5th minute after sternotomy
• ^{Group I}
  , Esmolol infusion group
• ^{Group B}
  , Esmolol bolus group
• ^{Group C}
  , Control group.
• ^*
  p < 0.05 compared with Group B and C.

AUC (heart rate, systolic, diastolic and mean arterial pressure × T _int (time from endotracheal intubation to sternotomy) and T _st (time from beginning of sternotomy to 5th min after sternotomy) were compared. According to Table 4, infusion group was significantly more effective than other two groups on controlling SAP during sternotomy and intubation. Moreover bolus group was significantly more effective than control group in controlling heart rate (HR) during sternotomy but no significant difference was observed between infusion and bolus group.

Table 4
AUC (HR, SAP, DAP and MAP × Tint and Tst) of groups.

	Group I (n = 15)	Group B (n = 15)	Group C (n = 15)
HR × Tint (cm2)	797 ± 114	853 ± 135	925 ± 189
HR × Tst (cm2)	188 ± 29	179 ± 33**	212 ± 40
SAP × Tint (cm2)	1218 ± 157*	1486 ± 254	1368 ± 185
SAP × Tst (cm2)	296 ± 51*	354 ± 67	374 ± 60
DAP × Tint (cm2)	726 ± 103	857 ± 192	777 ± 170
DAP × Tst (cm2)	246 ± 207	203 ± 45	203 ± 50
MAP × Tint (cm2)	968 ± 249	1078 ± 222	981 ± 154
MAP × Tst (cm2)	231 ± 33	255 ± 52	169 ± 51

• Data is presented as mean ± SD.
• ^HR
  , heart rate
• ^SAP
  , systolic arterial pressure
• ^DAP
  , diastolic arterial pressure
• ^MAP
  , mean arterial pressure
• ^TInt
  , time from endotracheal intubation to sternotomy
• ^Tst
  , time from beginning of sternotomy to 5th minute after sternotomy
• ^{Group I}
  , Esmolol infusion group
• ^{Group B}
  , Esmolol bolus group
• ^{Group C}
  , control group.
• ^*
  p < 0.05 compared with Group B and C.
• ^**
  p < 0.05 compared with Group C.

No adverse or side effects were recorded in both groups.

Discussion

This prospective, randomized, double blinded trial was designed to determine the hemodynamic effects of different use of esmolol during laryngoscopy, intubation and sternotomy in CABG surgeries and as a result of this study we found out that while esmolol infusion was significantly more effective than esmolol bolus on controlling SAP during both intubation and sternotomy, esmolol bolus was significantly more effective on controlling HR only during sternotomy when compared to control group but no significant difference was found when compared to infusion group. No significant side effects were observed.

Cardiovascular changes such as hypertension and tachycardia during tracheal intubation are potentially detrimental to patients with ischemic heart disease. Esmolol is the β-selective adrenergic blocker available and with its rapid onset and extremely short duration of action, would appear to be an ideal drug for preventing acute increases in HR and SAP.⁸

However, we would advise caution when using bolus and infusion doses of esmolol but no patient in our study required treatment for hypotension, bradycardia, or significant arrhythmias. No side effects were observed in any group of patients.

Since esmolol has been used clinically, its infusion use before CABG surgery or other procedures for preventing cardiac ischemia was studied and shown to be effective.⁹ As clinical use of esmolol became more common, due to its short acting, simple and effective bolus use of esmolol had increased.^{10 , 11 , 12 , 13 and 14}

According to our knowledge, the bolus and infusion administration of esmolol has not been compared before in a previous study, so we decided to design this study.

As an optimal intravenous (IV) esmolol dose for use during anesthesia induction (laryngoscopy and intubation) and emergence (extubation) has been previously determined to be 1.5 mg/kg, we used the same bolus dose in our study.^{15 and 16} As we could not find an optimal infusion dose of esmolol we used an average infusion dose that was 0.5 mg/kg/min in our study.¹⁷ While Parnass et al.¹³ were found no difference between 100 and 200 mg esmolol on controlling hemodynamic response during intubation, Yuan et al.¹² found out that 200 mg esmolol presented a better hemodynamic stability than 100 mg esmolol during induction of anesthesia in their study. Moreover, in another multicenter study, while IV bolus administration of 100 mg esmolol was being shown to be effective in controlling hemodynamic response of endotracheal intubation, 200 mg dosage was shown to cause more hypotension without desired effect.¹⁸

These controversial results indicated that other factors such as patients' medications, other diseases, ASA status, ages, intubation difficulties, different Mallampati scores might have affected the results and it is very important to standardize the patients' characteristics with even the clinicians who attempt to intubate. That is why in our study, patients were intubated by the same clinician who was blind to the study drug, to standardize the noxious stimuli during laryngoscopy and intubation. Moreover patients' medications and Mallampati scores were similar between groups.

In some previous studies patients were included into the study according to their medications with or without β-blocker agents.^{17 and 19} The results of these studies revealed that patients who enrolled to the these studies should have been chosen upon their treatment of β-blocker agents. In our study the patients on β-blocker agents were not included as similar to Korenaga et al's study. They excluded patients on β-blocker therapy from their study and reported a slight but statistically insignificant decrease in heart rate from 83 to 70 beat/min during infusion of esmolol 500 μg/kg/min prior to anesthetic induction.¹⁷ The same dose was used in our study and we also did not observe any significant decrease in HR.

But unlike our study, Brujin et al¹⁹ investigated the hemodynamic effects of esmolol in chronically β-blocked patients undergoing coronary artery bypass surgery and they concluded that in patients whom chronic β-blocker therapy was continued until the time of surgery, esmolol did not further attenuated the heart rate response but did attenuated the increase in blood pressure.

There are different doses of esmolol studied in previous studies and the choice of optimal dose of esmolol is very important to balance between the desired and side effects. Although we preferred 1.5 mg/kg bolus dose of esmolol and many studies showed the effectiveness of large doses of esmolol, Bensky et al.²⁰ compared 0.2 and 0.4 mg/kg esmolol and found out that both doses were more effective in decreasing the heart rate than control group and the 0.4 mg/kg dose significantly blunted the increase in mean arterial pressure seen in control group.

However, in another study,²¹ the result of a combination of nicardipine (30 μg/kg) and esmolol (1 mg/kg) showed no significant change in hemodynamic response to tracheal intubation when compared to saline.

There are also different techniques to find out the best one in previous studies. Some clinicians investigated the effect of esmolol bolus followed by esmolol infusion on hemodynamic effects to find out the most proper dose of esmolol.^{11 , 22 , 23 , 24 , 25 and 26} In a study made by Schäffer et al., double bolus of esmolol was used instead of one bolus to control the hemodynamic effect and they reached a better result with double bolus of 100 mg esmolol.²⁷ In another previous studies,^{28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 and 37} esmolol was compared with other agents alone or as combination.

These techniques and different doses of esmolol should be studied to use alone or in combination to find out the most appropriate one. However, it should be kept in mind that the patient characteristics and different procedures may affect the effects of Esmolol and other drugs.

There are some limitations of this current study. We did not calculate PCWP and cardiac index in our study. Those parameters would be a better guide for cardiac performance. We did not measure catecholamine levels of patients which would take us to more reliable results about the hemodynamic and stress response. Moreover the sample size of the study disabled us to demonstrate other factors that might enroll to the changes for hemodynamic parameters. As bolus dose was not as effective as on blood pressure, it might have been better to add another bolus dose group or make double boluses to investigate the effectiveness as the previous studies.

In conclusion, according to our study that the effect of esmolol bolus and infusion administration on hemodynamic response to laryngoscopy, endotracheal intubation and sternotomy in CABG surgery was compared, both groups were found safe and esmolol infusion was found more effective than esmolol bolus on controlling SAP during both intubation and sternotomy.

References

• ¹
  Kling D, Boldt J, Zickmann B, et al. The hemodynamic effects of a treatment with beta-receptor blockers during coronary surgery. A comparison between acebutolol and esmolol. Anaes- thesist. 1990;39:264-8.
• ²
  Kovac AL. Controlling the hemodynamic response of laryn- goscopy and tracheal intubation. J Clin Anesth. 1996;8:63-79.
• ³
  Wallace A, Layug B, Tateo I, et al. Prophylactic atenolol reduces postoperative myocardial ischemia. Anesthesiology. 1998;88:7-17.
• ⁴
  Deng CY, Lin SG, Zhang WC, et al. Esmolol inhibits Na+ current in rat ventricular myocytes. Methods Find Exp Clin Pharmacol. 2006;28:697-702.
• ⁵
  Figueredo E, Garcia-Fuentes: EM. Assessment of the efficacy of esmolol on the haemodynamic changes induced by laryngoscopy and tracheal intubation: a meta-analysis. Acta Anaesthesiol Scand. 2001;45:1011-22.
• ⁶
  Mion G, Ruttimann M, Descraques C, et al. Bolus esmolol prior to tracheal intubation of the elderly patient. Cah Anesthesiol. 1992;40:95-9.
• ⁷
  Zalunardo MP, Zollinger A, Szelloe P, et al. Cardiovascular stress protection following anesthesia induction. Comparison of cloni- dine and esmolol. Anaesthesist. 2001;50:21-5.
• ⁸
  Gorczynski RJ, Shaffer JE, Lee RJ. Pharmacology of ASL-8052, a novel beta-adrenergic receptor antagonist with an ultra- short duration of action. J Cardiovasc Pharmacol. 1983;5 6, 77.
• ⁹
  Newsome LR, Roth JV, Hug Jr CC, et al. Esmolol atten- uates hemodynamic responses during fentanyl-pancuronium anesthesia for aortocoronary bypass surgery. Anesth Analg. 1986;65:451-6.
• ¹⁰
  Kanitz DD, Ebert TJ, Kampine JP. Intraoperative use of bolus doses of esmolol to treat tachycardia. J Clin Anesth. 1990;2:238-42.
• ¹¹
  Reves JG, Croughwell ND, Hawkins E, et al. Esmolol for treat- ment of intraoperative tachycardia and/or hypertension in patients having cardiac operations. Bolus loading technique. J Thorac Cardiovasc Surg. 1990;100:221-7.
• ¹²
  Yuan L, Chia YY, Jan KT, et al. The effect of single bolus dose of esmolol for controlling the tachycardia and hypertension dur- ing laryngoscopy and tracheal intubation. Acta Anaesthesiol Sin. 1994;32:147-52.
• ¹³
  Parnass SM, Rothenberg DM, Kerchberger JP, et al. A single bolus dose of esmolol in the prevention of intubation-induced tachy- cardia and hypertension in an ambulatory surgery unit. J Clin Anesth. 1990;2:232-7.
• ¹⁴
  Sharma S, Ghani AA, Win N, et al. Comparison of two bolus doses of esmolol for attenuation of haemodynamic response to tracheal intubation. Med J Malaysia. 1995;50:372-6.
• ¹⁵
  Fuhrman TM, Ewell CL, Pippin WD, et al. Comparison of the efficacy of esmolol and alfentanil to attenuate the hemodynamic responses to emergence and extubation. J Clin Anesth. 1992;4:444-7.
• ¹⁶
  Dyson A, Isaac PA, Pennant JH, et al. Esmolol attenuates car- diovascular responses to extubation. Anesth Analg. 1990;71:675-8.
• ¹⁷
  Korenaga GM, Kirkpatrick A, Lord JG, et al. Effect of esmolol on tachycardia induced by endotracheal intubation. Anesth Analg. 1985;64:238.
• ¹⁸
  Miller DR, Martineau RJ, Wynands JE, et al. Bolus administration of esmolol for controlling the haemodynamic response to tra- cheal intubation: the canadian multicentre trial. Can J Anaesth. 1991;38:849-58.
• ¹⁹
  de Bruijn NP, Croughwell N, Reves JG. Hemodynamic effects of esmolol in chronically -blocked patients undergoing aortocoro- nary bypass surgery. Anesth Anal. 1987;66:137-41.
• ²⁰
  Bensky KP, Donahue-Spencer L, Hertz GE, et al. The dose- related effects of bolus esmolol on heart rate and blood pressure following laryngoscopy and intubation. AANA J. 2000;68:437-42.
• ²¹
  Tan PH, Yang LC, Shih HC, et al. Combined use of esmolol and nicardipine to blunt the haemodynamic changes fol- lowing laryngoscopy and tracheal intubation. Anaesthesia. 2002;57:1207-12.
• ²²
  Gold MI, Sacks DJ, Grosnoff DB, et al. Use of esmolol during anesthesia to treat tachycardia and hypertension. Anesth Analg. 1989;68:101-4.
• ²³
  Liu PL, Gatt S, Gugino LD, et al. Esmolol for control of increases in heart rate and blood pressure during tracheal intubation after thiopentone and succinylcholine. Can Anaesth Soc J. 1986;33:556-62.
• ²⁴
  Bilotta F, Lam MA, Doronzio A, et al. Esmolol blunts postop- erative hemodynamic changes after propofol-remifentanil total intravenous fast-track neuroanesthesia for intracranial surgery. J Clin Anesth. 2008;20:426-30.
• ²⁵
  Chia YY, Chan MH, Ko NH, et al. Role of b-blockade in anaesthe- sia and postoperative pain management after hysterectomy. Br J Anaesth. 2004;93:799-805.
• ²⁶
  Cork RC, Kramer TH, Dreischmeier B, et al. The effect of esmolol given during cardiopulmonary bypass. Anesth Analg. 1995;80:28-40.
• ²⁷
  Schäffer J, Karg C, Piepenbrock S:. Esmolol as a bolus for pre- vention of sympathetic adrenergic reactions following induction of anesthesia. Anaesthesist. 1994;43:723-9.
• ²⁸
  Ebert JP, Pearson JD, Gelman S, et al. Circulatory responses to laryngoscopy: the comparative effects of placebo, fentanyl and esmolol. Can J Anaesth. 1989;36 Pt 1:301-6.
• ²⁹
  Hussain AM, Sultan ST. Efficacy of fentanyl and esmolol in the prevention of haemodynamic response to laryngoscopy and endotracheal intubation. J Coll Physicians Surg Pak. 2005;15:454-7.
• ³⁰
  Gong Z, Luo A. Effects of alfentanil and esmolol on hemody- namic and catecholamine response to tracheal intubation. Chin Med Sci J. 1999;14:189-92.
• ³¹
  Fernandez-Galinski S, Bermejo S, Mansilla R, et al. Comparative assessment of the effects of alfentanil, esmolol or clonidine when used as adjuvants during induction of general anaesthesia. Eur J Anaesthesiol. 2004;21:476-82.
• ³²
  Bansal S, Pawar M. Haemodynamic responses to laryngoscopy and intubation in patients with pregnancy-induced hyperten- sion: effect of intravenous esmolol with or without lidocaine. Int J Obstet Anesth. 2002;11:4-8.
• ³³
  Atlee JL, Saeed Dhamee M, Olund TL, et al. The use of esmolol, nicardipine, or their combination to blunt hemody- namic changes after laryngoscopy and tracheal intubation. Anesth Analg. 2000;90:280-5.
• ³⁴
  Coloma M, Chiu JW, White PF, et al. The use of esmolol as an alternative to remifentanil during desflurane anesthesia for fast-track outpatient gynecologic laparoscopic surgery. Anesth Analg. 2001;92:352-7.
• ³⁵
  Feng CK, Chan KH, Liu KN, et al. A comparison of lidocaine, fen- tanyl, and esmolol for attenuation of cardiovascular response to laryngoscopy and tracheal intubation. Acta Anaesthesiol Sin. 1996;34:61-7.
• ³⁶
  Gupta S, Tank P. A comparative study of efficacy of esmolol and fentanyl for pressure attenuation during laryngoscopy and endotracheal intubation. Saudi J Anaesth. 2011;5:2-8.
• ³⁷
  Gaubatz CL, Wehner RJ. Evaluation of esmolol and fentanyl in controlling increases in heart rate and blood pressure during endotracheal intubation. AANA J. 1991;59:91-6.

Publication Dates

• Publication in this collection
  Jul-Aug 2014

History

• Received
  16 Apr 2013
• Accepted
  15 July 2013