Effects of intravenous and oral clonidine on hemodynamic and plasma-catecholamine response due to endotracheal intubation

Alpha2 Agonist Use in Critically Ill Adults: A Focus on Sedation and Withdrawal Prevention

The management of sedation in critically ill adults poses a unique challenge to clinicians. Dexmedetomidine, an α2 agonist, has a unique mechanism and favorable pharmacokinetics, making it an attractive intravenous option for sedation and delirium in the intensive care unit. However, patients may be at risk for withdrawal with prolonged use, adding to the complexity of sedation and agitation management in this patient population. Enteral α2 agents have the benefit of cost savings and ease of administration, thus playing a role in the ability to decrease intravenous sedative use and prevent dexmedetomidine withdrawal. Clonidine and guanfacine are the two most common enteral α2 agents utilized for this purpose, however, there is a paucity of evidence regarding the comparative benefit between the two agents. The decision to use one vs the other agent should be determined based on their differing pharmacology, pharmacokinetics, and side effect profile. The most effective dosing strategy for these agents is also unknown. Ultimately, more robust literature is required to determine enteral α2 agonists place in therapy. This narrative review evaluates the currently available literature on the use of α2 agonists in critically ill adults with an emphasis on sedation, delirium, and withdrawal.

Comparative Study Between Intravenous Clonidine and Preservative Free Intravenous Lignocaine in Attenuation of Pressor Response to Laryngoscopy and Endotracheal Intubation

Objectives

To compare the attenuation of pressor responses by intravenous clonidine and preservative-free lignocaine to laryngoscopy and endotracheal intubation.

Materials and Methods

A randomized, prospective, comparative, double-blinded study was conducted in 80 adult patients who were randomized into two groups of 40 each, group clonidine (Group C) and group lignocaine (Group L). Group C patients were given 2 µg/kg clonidine in 20 ml of normal saline as a slow infusion over 10 min prior to intubation. Group L patients were given 1.5 mg/kg of preservative-free 2% lignocaine in 20 ml of normal saline as a single-dose infusion over 3 min prior to intubation. Baseline vital and hemodynamic parameters were monitored during the perioperative period at 1-, 5-, and 10-min post-intubation.

Results

The attenuation of heart rate (HR) after intubation was much better with clonidine than lignocaine as there is statistically significant difference in the mean HR between the two groups at 1, 5, and 10 min after intubation with the HR significantly lesser in the Group C than the Group L at all times after intubation. Both clonidine and lignocaine were effective in attenuating systolic blood pressure response after intubation, but clonidine was more effective than lignocaine as systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) in the Group C remained much lower than the Group L and the difference between the two groups was statistically significant at all times after intubation.

Conclusion

Premedicating with a single slow infusion of 2 µg/kg i.v. clonidine has been proven to be effective in maintaining perioperative hemodynamic stability at 1, 5, and 10 min post-intubation than lignocaine.

Cardiovascular Safety of Clonidine and Dexmedetomidine in Critically Ill Patients after Cardiac Surgery

Purpose

The aim of this retrospective study was to assess the haemodynamic adverse effects of clonidine and dexmedetomidine in critically ill patients after cardiac surgery.

Methods

2769 patients were screened during the 30-month study period. Heart rate (HR), mean arterial pressure (MAP), and norepinephrine requirements were assessed 3-hourly during the first 12 hours of the continuous drug infusion. Results are given as median (interquartile range) or numbers (percentages).

Results

Patients receiving clonidine (n = 193) were younger (66 (57-73) vs 70 (63-77) years, p=0.003) and had a lower SAPS II (35 (27-48) vs 41 (31-54), p=0.008) compared with patients receiving dexmedetomidine (n = 141). At the start of the drug infusion, HR (90 (75-100) vs 90 (80-105) bpm, p=0.028), MAP (70 (65-80) vs 70 (65-75) mmHg, p=0.093), and norepinephrine (0.05 (0.00-0.11) vs 0.12 (0.03-0.19) mcg/kg/min, p < 0.001) were recorded in patients with clonidine and dexmedetomidine. Bradycardia (HR < 60 bpm) developed in 7.8% with clonidine and 5.7% with dexmedetomidine (p=0.51). Between baseline and 12 hours, norepinephrine remained stable in the clonidine group (0.00 (-0.04-0.02) mcg/kg/min) and decreased in the dexmedetomidine group (-0.03 (-0.10-0.02) mcg/kg/min, p=0.007).

Conclusions

Dexmedetomidine and the low-cost drug clonidine can both be used safely in selected patients after cardiac surgery.

Clonidine as an Adjuvant to Lignocaine Infiltration for Prolongation of Analgesia after Episiotomy

Background:

Epidural labor analgesia has not been fully accepted despite many advantages. Many times, the pregnant females reach hospital without antenatal checkup, and at that time, “episiotomy infiltration” becomes an ideal method for vaginal delivery. One of the most important problems after episiotomy is the severe perineal pain on the 1^st day of postpartum period.

Objectives:

We compared the efficacy of clonidine 1 μg/kg as an adjuvant to 20 mg/ml lignocaine infiltration along the line of episiotomy incision for prolonging the duration and quality of analgesia with respect to various activities by single injection.

Methodology:

Majority of the patients, 94.2% in our study, had no idea about labor analgesia, and only 2.5% of all the patients expressed their interest to deliver without suffering from labor pains. One hundred and twenty pregnant female patients scheduled for full-term vaginal delivery were assigned into lignocaine and lignocaine-clonidine group according to infiltration they received. Pain scoring using visual analog scale and maternal satisfaction scale was monitored. At the end of the research project, the data were compiled and analyzed using appropriate statistical tests.

Results:

Duration of analgesia after episiotomy during sitting, walking, and squatting was 22.7 ± 1.32, 21.73 ± 1.47, and 19.875 ± 1.48 h in clonidine + lignocaine group and 6.06 ± 1.26, 5.33 ± 1.18, and 4.01 ± 1.28 h in lignocaine only group, respectively, which was highly statistically significant P < 0001.

Conclusions:

Clonidine when added to 2% lignocaine infiltration in episiotomy improves the quality and significantly enhances the duration of analgesia.

Comparision of clonidine and dexmedetomidine for attenuation of laryngoscopy and intubation response - A randomized controlled trial

BACKGROUND

Clonidine and dexmedetomidine are alpha-2 agonists with beneficial effect on the hemodynamic response to laryngoscopy and intubation. The present study was designed to evaluate and compare the efficacy of intravenous clonidine 1 μg/kg, and dexmedetomidine in doses of 0.5 μg/kg and 1 μg/kg, for blunting the hemodynamic changes during laryngoscopy and intubation.

METHOD

Adult patients of ASA physical grade I/II scheduled for surgery under general anaesthesia with endotracheal tube were randomly divided into three groups using a computer generated random number table, each group receiving one of the following drugs prior to induction of anaesthesia, by a blinded anaesthesiologist in a volume of 100 mL infused intravenously over 20 minutes: clonidine 1 μg/kg, or dexmedetomidine 0.5 μg/kg, or dexmedetomidine 1 μg/kg. General anaesthesia was induced using standard technique and intubations performed by same anaesthesiologist. Heart rate and mean blood pressure were recorded in pre-operative room (baseline) and again at 1 minute, 3 minutes, 5 minutes and 10 minutes after intubation. An increase in heart rate and/or mean blood pressure by >20% above baseline values during observation period was taken to indicate a positive intubation response.

RESULTS

The incidence of intubation response was similar in all three groups (P>.05). The number of patients developing hypotension was significantly higher in group receiving dexmedetomidine1μg/kg group (P<.005) as compared to other two groups. Both the groups receiving dexmedetomidine had higher number of patients developing bradycardia as compared to patients receiving clonidine.

DISCUSSION & CONCLUSION

Dexmedetomidine 0.5 μg/kg, 1 μg/kg and clonidine 1 μg/kg attenuate the laryngoscopy and intubation response but Clonidine 1 μg/kg was associated with lesser side effects.

Comparison of fentanyl and clonidine for attenuation of the haemodynamic response to laryngocopy and endotracheal intubation

INTRODUCTION

Laryngoscopy and tracheal intubation after the induction of anaesthesia, are nearly always associated with sympathetic hyperactivity. To 'blunt' this pressor response, various methods have been tried, but very few studies have been done to assess the effects of fentanyl orI.V. clonidine on the haemodynamic response during laryngoscopy and tracheal intubation. The purpose of this study was to compare these agents, to find the drug which was best suited for this purpose and the most favourable time for its administration.

METHODS

This was a prospective study which involved 3 groups of patients. The patients in group-1 (control) were given normal saline and the groups 2 and 3 were given i.v. fentanyl and clonidine respectively. Each group had 50 patients who presented for elective, non-cardiovascular surgeries. All the patients were ASA-1 or ASA-II and were operated in PESIMSR, Kuppam.

RESULTS

The heart rate rise was 48.07% in the control group, whereas it was significantly lower in the fentanyl (II) 27.75% and the clonidine groups (III) 12.57% (p<0.001). In the control group, the systolic blood pressure increased maximally after 5 minutes (42.62%) i.e., immediately after the laryngoscopy and the intubation. It decreased gradually over 10 minutes (17.39%). With the administration of fentanyl, the maximum increase as compared to the preinduction value was 9.91%, but it was only 7.38% in the clonidine group. Both, when they were compared with the control, showed a significant suppression (P<.001), with clonidine showing better results. The maximum increase in the diastolic blood pressure was 30.12% in the control group (P<.001) at 5 min and it was 18.22%, and 6.15% in the fentanyl and the clonidine groups respectively, with clonidine faring better again (P<.001).

INTERPRETATION AND CONCLUSION

Clonidine showed better attenuation of the sympathetic response, which is statistically highly significant and it remained so till the end of 10 minutes. Intravenous clonidine 2;g/kg which is administered 5 minutes before the laryngoscopy can be recommended to attenuate the sympathetic response to the laryngoscopy and the intubation.

Hemodynamic stress response during laparoscopic cholecystectomy: Effect of two different doses of intravenous clonidine premedication

Background:

Clonidine has emerged as an attractive premedication desirable in laparoscopic surgery wherein significant hemodynamic stress response is seen. The minimum safe and effective dose of intravenous clonidine to attenuate the hemodynamic stress response during laparoscopic surgery has however not yet been determined.

Materials and Methods:

This prospective, randomized, double-blind controlled study was conducted on 90 adults of ASA physical status I and II, scheduled for laparoscopic cholecystectomy under general anesthesia. Patients were randomized to one of the three groups (n= 30). Group I received 100 ml of normal saline, while groups II and III received 1 μg/ kg and 2 μg/ kg of clonidine respectively, intravenous, in 100 ml of normal saline along. All patients received glycopyrrolate 0.004 mg/kg and tramadol 1.5 mg/kg intravenously, 30 min before induction. Hemodynamic variables (heart rate, systolic, diastolic, mean arterial pressure), SpO2, and sedation score were recorded at specific timings. MAP above 20% from baseline was considered significant and treated with nitroglycerine.

Results:

In group I, there was a significant increase in hemodynamic variables during intubation pneumoperitoneum and extubation (P<0.001). Clonidine given 1 μg/kg intravenous attenuated hemodynamic stress response to pneumoperitoneum (P<0.05), but not that associated with intubation and extubation. Clonidine 2 μg/kg intravenous prevented hemodynamic stress response to pneumoperitoneum and that associated with intubation and extubation (P<0.05). As against 14 and 2 patients in groups I and II respectively, no patient required nitroglycerine infusion in group III.

Conclusions:

Clonidine, 2 μg/ kg intravenously, 30 min before induction is safe and effective in preventing the hemodynamic stress response during laparoscopic cholecystectomy.

Effects of oral clonidine premedication on haemodynamic response to laryngoscopy and tracheal intubation: a clinical trial

The objective of this study was to evaluate the efficacy of pre-anesthetic orally administration of clonidine on pulse rate and blood stress response to laryngoscopy and tracheal intubation. In a double-blinded, randomized study, 274 ASA I and II subjects with age of 18 to 45 years scheduled for elective surgery under general anesthesia were enrolled. They were randomly allocated to receive oral clonidine (0.2 mg) or placebo as premedication 90-120 min before surgery. All the patients received Succinylcholine (1.5 mg kg(-1)) after induction of anesthesia with Fentanyl (50 microg) and Thiopentone (5 mg kg(-1)). The anesthesia was maintained with halothane (1.5 Mac) in 50% mixture of N2O/O2. Heart rate and systolic blood pressure were recorded before, immediately after and then every 5 min after intubation until 20 min. The Clonidine group showed a significant superiority over placebo in the prevention of increase in systolic blood pressure as well as heart rate over the intubation. A significant difference was observed in both heart rate and systolic blood pressures were significantly higher in Control group at three subsequent measurements following intubation. The results of this study suggest that orally administered clonidine in preanesthetic period, provides more haemodynamic stability and attenuates the stress response to laryngoscopy and intubation.

[Quality of premedication and patient satisfaction after premedication with midazolam, clonidine or placebo : Randomized double-blind study with age-adjusted dosage]

BACKGROUND

Premedication aims at alleviating preoperative anxiety and nervousness and also at minimizing adverse effects. To our knowledge there is no study comparing efficacy and patient satisfaction of different premedications in age-adjusted dosage.

METHODS

In 139 patients anxiety, sedation and adverse effects were measured at 6 consecutive perioperative time points after administration of midazolam, clonidine or a placebo.

RESULTS

Midazolam showed the strongest sedative and anxiolytic effects, clonidine less and placebo none. Clonidine and midazolam reduced the risk of postoperative nausea and vomiting (PONV). Midazolam showed minimal adverse effects and the best patient satisfaction.

CONCLUSION

Midazolam was the most anxiolytic, sedative and favored premedication with the least adverse effects. Most patients would choose midazolam next time.

Dexmedetomidine: perioperative applications in children

Dexmedetomidine is a highly specific and selective alpha-2-adrenergic agonist with sedative, anxiolytic, and organ protective effects. Its clinical applications in children include premedication, prevention of emergence delirium, as part of multimodal anesthetic regimen and sedation in the pediatric intensive care unit. Its role in neuroprotection in children undergoing anesthesia should be explored. In this review, various uses of dexmedetomidine are discussed in detail.

The effect of clonidine on perioperative blood coagulation

STUDY OBJECTIVE

To evaluate the influence of perioperative stress protection by clonidine on blood coagulation.

DESIGN

Prospective, randomized, double-blinded, placebo-controlled clinical trial.

SETTING

University hospital.

PATIENTS

50 patients scheduled for elective gynecoabdominal surgery.

INTERVENTIONS AND MEASUREMENTS

Patients were randomly assigned to control (placebo) or clonidine group (single intravenous clonidine dose; 4 microg/kg(-1) or 3 microg/kg(-1) for age >65 years). Three measurement time points were defined: before administration of placebo/clonidine and anesthesia induction, (t1; baseline measurement); after surgery, before emergence of anesthesia (t2); and at the first postoperative day, 24 hours after anesthesia induction (t3). Blood coagulation was analyzed at all time points measuring international normalized ratio, platelets, thrombin-antithrombin complex, von Willebrand factor, soluble thrombomodulin, d-dimers, plasminogen activator inhibitor 1, and Thrombelastograph analysis.

MAIN RESULTS

In the postoperative period (t2, t3), hypercoagulability was present in all patients compared with baseline measurements (t1) but without differences between the control and clonidine group. Regarding hematologic, laboratory blood coagulation, and Thrombelastograph parameters, there was no statistically and clinically relevant difference throughout the study period between the 2 groups. No hemodynamic adverse events of clonidine were observed in the perioperative period. Until day of discharge, no thrombotic or thromboembolic events were reported in both groups.

CONCLUSIONS

Preoperative administration of a single dose of clonidine has no effect on perioperative blood coagulation.

Which is responsible for the haemodynamic response due to laryngoscopy and endotracheal intubation? Catecholamines, vasopressin or angiotensin?

BACKGROUND AND OBJECTIVE

We have investigated the concentrations of epinephrine, norepinephrine, vasopressin and angiotensin converting enzyme activity to explore the role of these mediators in the neuroendocrine response to laryngoscopy and tracheal intubation.

METHODS

One hundred (50 male, 50 female) ASA I patients aged 20-50 yr (mean+/-SEM; 35.59+/-0.99) were included in the study. They were undergoing elective surgery under standard anaesthesia induction and maintenance using tracheal intubation. Plasma concentrations of epinephrine, norepinephrine and vasopressin as well as plasma angiotensin converting enzyme activity were determined at four time points, before (T1) and after (T2) induction, and 2 (T3) and 5 min (T4) after intubation. Blood pressure and heart rate were recorded at corresponding times to reveal if any correlation existed between haemodynamic parameters and neuroendocrine response.

RESULTS

Heart rate increased after induction and intubation (P<0.05) and decreased significantly at T4 (P<0.05). Systolic blood pressure decreased significantly (P<0.05) after induction and increased slightly after intubation decreasing to below baseline value (P<0.05) at T4. Diastolic blood pressure increased slightly after intubation and decreased significantly (P<0.05) at T4. Plasma epinephrine and norepinephrine concentrations decreased after induction and increased at T3 and T4 without reaching significance. Vasopressin concentrations increased slightly at T2 and T3 and decreased significantly at T4 (P<0.05). Angiotensin converting enzyme activity was unaffected when compared with baseline values.

CONCLUSIONS

Blood pressure, heart rate, plasma epinephrine, norepinephrine and vasopressin concentrations increased slightly in response to laryngoscopy and intubation, all returning to or below baseline 5 min later with no change in angiotensin converting enzyme activity in normotensive patients.

The role of α2-agonists in neurosurgery

Alpha2-agonists have been extensively used and studied in anaesthesia and intensive care medicine. A list of benefits includes anxiolysis, blood pressure stabilization, analgesia, anaesthetic sparing effects and sedation without respiratory depression or significant cognitive impairment. Fear of inadvertent hypotension, bradycardia or post-operative sedation, and the variability of the haemodynamic response to different doses or rates of administration, have meant that universal acceptance in clinical practice has not yet been seen. Recently, the actions of these agents on the alpha2-adrenoreceptor and the imidazoline receptor have been more accurately identified, helping to explain the differences between the actions of various agents. The two readily available agents, clonidine and dexmedetomidine have already been used in many different anaesthetic situations, for a wide variety of surgical procedures. We believe that both of these alpha2-agonists are useful adjuncts for the management of the neurosurgical patient during surgery, and in the intensive care unit.

Clonidine as a pre-anesthetic agent for flexible bronchoscopy

Several drugs have been employed for sedation during flexible fiberoptic bronchoscopy (FOB). Clonidine attenuates stress-induced sympathoadrenal responses and has sedative properties. We investigate the effects of clonidine premedication on hemodynamic and comfort parameters of patients submitted to FOB under airway topical anesthesia only. Patients received placebo (n = 22; men = 16; median age = 50.5 years) or intravenous clonidine (3 microg/kg; n = 20; men = 15; median age = 46.0 years) 15 min before FOB. Blood pressure (BP), heart rate (HR), plasma norepinephrine (nor) and cortisol levels were measured before, during, and 1 h after FOB. Comfort was assessed by the examiner and by the patients using a visual numerical scale (0-10). The placebo group showed significant increases in systolic BP, HR, and nor levels during FOB (SBP = 125 mmHg x 145 mmHg; HR = 74 bpm x 85 bpm; nor = 316.2 pg/dl x 483.1 pg/dl), whereas clonidine group did not display such changes. Clonidine group showed a lower frequency of cardiac arrhythmias than the placebo group during and after FOB (supraventricular = 39% x 50%; ventricular = 22% x 40%). Levels of comfort were high and comparable in both groups. We concluded that although clonidine led to a somewhat better hemodynamic profile, it did not contribute to better comfort in this setting.

Preoperative clonidine blunts hyperadrenergic and hyperdynamic responses to prolonged tourniquet pressure during general anesthesia

Although the mechanism of tourniquet-induced hypertension is still unclear, plasma norepinephrine concentrations continuously increase in parallel to arterial blood pressure during tourniquet inflation. Clonidine attenuates hyperadrenergic and hyperdynamic responses. We investigated the effects of clonidine on prolonged tourniquet inflation. Twenty-nine patients scheduled for elective orthopedic surgery were randomly assigned to receive IV clonidine (3 microg/kg; n = 14) or placebo (n = 15) before tourniquet inflation of the lower limbs under general anesthesia in a double-blinded manner. Arterial blood pressure, heart rate, epinephrine, and norepinephrine plasma concentrations were measured before tourniquet inflation, 60 min after tourniquet inflation, just before tourniquet deflation, and 20 min after tourniquet deflation. Mean arterial blood pressure and norepinephrine plasma-concentrations were significantly lower in the Clonidine group compared with Control after 60 min tourniquet inflation (P = 0.016; P = 0.006). Immediately before deflation of the tourniquet, the difference for mean arterial pressure between groups was even more pronounced (P = 0.005). Twenty minutes after deflation mean arterial blood pressure in the Control group was still increased and significantly higher compared with the Clonidine group (P = 0.002). In conclusion, preoperative IV clonidine blunts hyperadrenergic and hyperdynamic responses resulting from prolonged tourniquet inflation under general anesthesia in ASA class I--II patients.

IMPLICATIONS

Tourniquet inflation is associated with a continuous increase in arterial blood pressure and sympathetic outflow. This study shows that IV clonidine effectively blunts increases of both arterial blood pressure and plasma norepinephrine concentrations.

Sedation in outpatient bronchoscopy

Bronchoscopy is a procedure that is likely to provoke anxiety as the patient is surrounded by monitoring and bronchoscopy equipment, and care is administered by strangers who perform intimate, invasive, and sometimes, painful procedures. Sedation is needed, therefore, to allay anxiety and reduce stress, improve patient comfort and co-operation, provide amnesia and facilitate the bronchoscopic procedure. In this review we try to summarize the current knowledge on currently used sedation protocols with special reference to the commonly used pharmacological agents. We believe sedation should be used routinely in fiberoptic bronchoscopy in order to achieve a safe and pleasant procedure for both the patient and the pulmonologist.

The effect of clonidine premedication on hemodynamic responses to microlaryngoscopy and rigid bronchoscopy

The usual hemodynamic response to laryngoscopy and bronchoscopy is an increase in heart rate and arterial blood pressure. Previous work has reported that 10%-18% of the patients develop ischemic ST segment changes during the procedure. Therefore, we performed a prospective, randomized, double-blinded study in 36 patients scheduled for elective microlaryngeal and bronchoscopic surgical procedures to evaluate the effects of 300-microg oral clonidine premedication (n = 18) or placebo (n = 18) on the hemodynamic alterations and the incidence of perioperative myocardial ischemic episodes. Myocardial ischemia was assessed by using continuous electrocardiographic monitoring, beginning 30 min before, and lasting until 24 h after the operation. During the procedure, patients receiving placebo exhibited a significant increase (mean +/- SD) in arterial blood pressure (the systolic increasing from 137+/-11 to 166+/-17 mm Hg, the diastolic increasing from 80+/-11 to 97+/-14 mm Hg) and heart rate (increasing from 79+/-15 to 97+/-12 bpm) compared with the baseline and with the clonidine group. A dose of 300-microg clonidine blunted the hemodynamic response to endoscopy. Ventricular arrhythmias were more frequent in patients who were not premedicated with clonidine. Two patients in the control group, but none in the clonidine group, had evidence of myocardial ischemia. These data should encourage routine premedication with clonidine in patients undergoing microlaryngoscopic and bronchoscopic procedures.

Preoperative clonidine attenuates stress response during emergence from anesthesia

STUDY OBJECTIVES

To investigate whether a single preoperative IV dose of clonidine blunts the hemodynamic and hyperadrenergic responses not only to intubation, but also to extubation.

DESIGN

Randomized, double-blind, placebo-controlled study.

PATIENTS

29 ASA physical status I and II patients (ages 18-65) who were scheduled for noncardiac, elective surgery. Patients were randomly assigned to either receive clonidine 3 microg/kg IV immediately before anesthesia induction or placebo.

INTERVENTIONS

Insertion of a 14 G cannula in a large cubital vein for the determination of plasma catecholamines using local anesthesia. Insertion of a radial artery catheter for measuring blood pressure (BP) using local anesthesia. Transthoracic echocardiography to determine cardiac output (CO).

MEASUREMENTS

Heart rate (HR), mean arterial pressure (MAP), CO, and plasma catecholamine concentrations. Measurements were performed: before induction (baseline), during intubation, 10 min after intubation, after surgery, during extubation, and 10 min after extubation.

MAIN RESULTS

During intubation MAP, HR, and CO were lower in the clonidine group. Compared with baseline measurements, MAP and CO increased less in the clonidine group during intubation. During extubation, MAP was lower in the clonidine group. CO and MAP increased less as compared with baseline measurements in the clonidine group. Compared with the measurements after surgery CO less in the clonidine group during extubation (p < 0.05 for all results).

CONCLUSIONS

A single preoperative IV dose of clonidine (3 microg/kg) blunts the hemodynamic responses due to extubation in noncardiac surgery of intermediate duration.

The effect of clonidine pretreatment on the perioperative proinflammatory cytokines, cortisol, and ACTH responses in patients undergoing total abdominal hysterectomy

We investigated the hypothesis that oral clonidine premedication would decrease the release of proinflammatory cytokines interleukin (IL)-6, IL-1beta, and tumor necrosis factor-alpha, and stress hormones cortisol and adrenocorticotropic hormone (ACTH), in patients who underwent total abdominal hysterectomy. Twenty patients were randomly assigned to one of two groups: the control group received no premedication, whereas the treatment group received clonidine 0.15 mg oral dose 90 min before surgery. Venous blood samples were obtained at preinduction time and immediately, 1, and 3 h after the start of surgery. IL-6 increased significantly at 3 h, and cortisol and ACTH at 1 and 3 h after the start of surgery compared with the baseline values within both groups. IL-1beta levels decreased at all times compared with the baseline value in the control group. In the comparison study between the control group and the clonidine group, there was a significant decrease in IL-6 level 3 h after the start of surgery and IL-1beta at preinduction time in the clonidine group, whereas there were no changes in tumor necrosis factor-alpha, cortisol, and ACTH levels. These results show that clonidine modulates the IL-6 response related to surgical stress.

IMPLICATIONS

We assessed the effect of the alpha(2)-adrenoreceptor agonist clonidine on the immunoendocrine activity during the perioperative period. Clonidine 0.15 mg given as oral premedication resulted in the reduced Interleukin-6 production in response to total abdominal hysterectomy.

Massive esophageal variceal hemorrhage triggered by complicated endotracheal intubation

Esophageal variceal hemorrhage is frequently a catastrophic event. The specific events that trigger variceal rupture are not well understood. Acute elevations in systemic blood pressure and increased splanchnic blood flow, however, may lead to increased intravariceal pressure followed by variceal rupture and hemorrhage. This report describes a strong temporal association between complicated endotracheal intubation and abrupt onset of life-threatening variceal hemorrhage. A 52-year-old man with a history of portal hypertension was intubated emergently for airway protection because of respiratory insufficiency due to sepsis. Intubation was complicated by initial inadvertent esophageal intubation and by a peak mean arterial blood pressure of 155 mmHg. At the conclusion of the procedure, the patient sustained large volume hematemesis due to esophageal variceal rupture. This case suggests a risk of triggering variceal hemorrhage as a result of intubation-induced increase in blood pressure. A number of agents, including fentanyl, have been shown to be effective in attenuating the cardiovascular response to intubation. This case report provides strong evidence in support of administering fentanyl, or a suitable alternative adjunctive medication, before intubation of patients with documented portal hypertension and a history of esophageal variceal hemorrhage.

Effect of clonidine premedication on haemodynamic responses to fibreoptic bronchoscopy

The usual haemodynamic response to fibreoptic bronchoscopy is an increase in heart rate and blood pressure. We therefore compared, in a prospective, randomised, double-blind study, the effect of two doses of oral clonidine premedication (150 microg or 300 microg) with placebo (control group) on the haemodynamic alterations in 62 patients who underwent elective fibreoptic bronchoscopy. Significant increases in blood pressure and heart rate were observed during fibreoptic bronchoscopy only in the control group. Clonidine 150 microg blunted the haemodynamic response to fibreoptic bronchoscopy (p < 0.05). Significant decreases in systolic blood pressure (< 90 mmHg) were observed in all patients premedicated with 300 microg clonidine. Throughout the study nine patients (75%) in the 300 microg clonidine group were treated at least once for hypotension. Compared with the control group, time to awakening was significantly longer only in patients premedicated with 300 microg clonidine. In conclusion, premedication with 150 microg oral clonidine attenuates haemodynamic responses to fibreoptic bronchoscopy, without causing excessive haemodynamic depression and sedation. These data encourage the administration of clonidine as premedication in patients undergoing fibreoptic bronchoscopy, particularly in those with, or at risk for, coronary artery disease.