Cardiovascular reactions to laryngoscopy and tracheal intubation following small and large intravenous doses of lidocaine

Topical larynx lidocaine Spraying reduces cardiovascular stress response caused by suspension laryngoscopic surgery

OBJECTIVE

This study aimed to investigate the potential reduction of cardiovascular stress response caused by suspension laryngoscopic surgery through the application of lidocaine spray on the larynx and trachea.

METHODS

A total of 68 patients scheduled for elective suspension laryngoscopic surgery were randomly assigned to either the lidocaine group (Group L, n = 34) or the control group (Group C, n = 33). In Group L, patients received a sprayed lidocaine dose of 2 mg/kg on the larynx and trachea after anesthesia induction, prior to intubation. In Group C, equal volumes of saline solution were administered. MAP and HR were recorded at various time points: before anesthesia (T0), 1-minute after intubation (T1), 1 and 3 min after suspension laryngoscopy (T2 and T3), at the end of the operation (T4), and at 1, 5, and 30 min after extubation (T5, T6, and T7). Arterial blood glucose, epinephrine, and norepinephrine levels were measured at T0, T2, T5, and T7. The occurrence of severe cough and sore throat at T6 and T7 after extubation was compared between the two groups.

RESULTS

At T0 and T1, there were no statistically significant differences in mean arterial pressures, heart rate, and blood catecholamine levels between the two groups. However, from T2 to T7, the blood pressure and heart rate in Group L were lower compared to Group C, with significant differences observed at T2‒T6 (p < 0.05). Group L also showed less elevation in blood glucose at T2, T5, and T7 (p < 0.05). The changes in epinephrine and norepinephrine levels between the two groups were statistically significant at T2 and T5 (p < 0.05).

CONCLUSIONS

Administering lidocaine spray on the larynx and trachea during intubation for suspension laryngoscopic surgery can effectively alleviate the stress response. LEVEL 1 EVIDENCE: Patients in this study are randomly assigned to the treatment or control group and are followed prospectively.

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.

Comparison of intravenous injection of magnesium sulfate and lidocaine effectiveness on the prevention of laryngospasm and analgesic requirement in tonsillectomy

The aim of the present study is to compare the effect of intravenous (IV)injectionof magnesium sulfate and lidocaine on the prevention of laryngospasm, and analgesic requirement in tonsillectomy surgeries. In this double-blinded clinical trial, 62 children are randomly selected and categorized into two groups. Two minutes after intubation, group A received 15 mg/kg IV magnesium sulfate, while group B received 1 mg/kg IV 2% lidocaine. Laryngospasm frequency, nausea and vomiting, hemodynamic status (in 15 minutes after extubating), sedation score, analgesic requirement, and duration of recovery were compared between the two groups. Data were analyzed using SPSS software version 21 and with a 95% confidence interval. Both groups had no significant difference based on the age and weight means, as well as sex frequency. 10 patients (32.3%) in the lidocaine group and 3 patients in the magnesium group (9.7%) had stridor, and the difference between the two groups was statistically significant (p = 0.026). Laryngospasm only occurred in a patient of the lidocaine group. The frequency of nausea and vomiting, agitation and analgesic requirement in the lidocaine group were higher than the magnesium group (p= 0.001). However, sedation score and recovery time were higher in the magnesium group (p=0.001). No statistically significant difference was seen between the two groups in terms of hemodynamics. Magnesium sulfate and lidocaine had no difference in the incidence of laryngospasm, but magnesium sulfate was associated with a lower rate of stridor, nausea, vomiting, agitation and analgesic requirement in recovery in comparison to lidocaine.

Intravenous fentanyl vs. topical lignocaine for ProSeal™ laryngeal mask airway insertion with propofol induction

Insertion of the laryngeal mask airway (LMA) without muscle relaxant requires adequate obtundation of airway reflexes, which may otherwise lead to incorrect or failed LMA placement. This study compared topical lignocaine spray vs. intravenous (IV) fentanyl, during propofol induction for insertion of the ProSeal™ LMA (PLMA). This was a prospective, randomized, double blind study, in ASA I or II patients, for elective or emergency surgery. Seventy patients (n = 70) who fulfilled the inclusion criteria were randomly assigned to receive IV fentanyl 2 mcg/kg or topical lignocaine spray 40 mg, prior to anesthesia induction with IV propofol (2–2.5 mg/kg). ProSeal™ LMA insertion condition was regarded optimal in the absence of adverse responses (gag, cough, laryngospasm and body movements), and successful LMA placement at the first attempt. Hemodynamic parameters were recorded and patients were assessed for sore throat and hoarseness post operatively. Seventy patients were analyzed. The number of patients with optimal PLMA insertion conditions were comparable between the groups (60% vs. 57%, P = 0.808). All hemodynamic parameters were comparable between groups with the exception of heart rate. Sympathetic obtundation of heart rate was greater with IV fentanyl than topical lignocaine (P < 0.05). The proportion of patients with postoperative sore throat significantly increased with the number of insertion attempts (P < 0.05). Topical lignocaine spray to the pharynx is as effective, and may be an alternative to IV fentanyl, during propofol induction for PLMA insertion. Success rate and optimal insertion condition at the first attempt, propofol requirement, blood pressure, adverse events and airway complications were comparable. Heart rate obtundation was less with topical lignocaine spray but remained within clinically acceptable values.

Remifentanil vs. Lignocaine for Attenuating the Haemodynamic Response during Rapid Sequence Induction Using Propofol: Double-Blind Randomised Clinical Trial

This study was conducted to determine whether lignocaine or remifentanil effectively attenuate the response to endotracheal intubation during rapid sequence induction. Forty-eight patients were randomly divided into three groups: Group NS (n=16) received normal saline 0.1 ml/kg, Group L (n=16) received lignocaine 1.5 mg/kg, and Group R (n=16) received remifentanil 1 /μg/kg. Anaesthesia was induced with propofol 2 mg/kg after glycopyrrolate 0.2 mg IV. Each study drug was given intravenously over 30 seconds after loss of consciousness. Cricoid pressure was applied until intubation. Succinylcholine 1.0 mg/kg was administered to facilitate tracheal intubation. After intubation, the patient's lungs were ventilated with sevoflurane 1% and nitrous oxide 50% in oxygen. Mean arterial pressure and heart rate were recorded before induction, at loss of consciousness, immediately before laryngoscopy and every minute after intubation for 10 minutes. Mean arterial pressure fell following propofol in all groups. The maximum increase in mean arterial pressure in Group NS and Group L were 46% and 38% respectively above the baseline value one minute after intubation, whereas the mean arterial pressure in Group R increased only back to the baseline value. Heart rate in Group NS and Group L were increased by 27% and 33% above baseline value respectively one minute after intubation, while that in Group R was increased only to the baseline value. The results indicate that remifentanil 1 μg/kg, but not lignocaine 1.5 mg/kg, effectively attenuates the haemodynamic response to endotracheal intubation during rapid sequence induction using propofol.

Evaluation of lignocaine infusion on recovery profile, quality of recovery, and postoperative analgesia in patients undergoing total abdominal hysterectomy

Background and Aims:

Multimodal analgesia entrains the use of drugs in perioperative period producing adequate pain relief without affecting the quality of recovery by decreasing drug-related adverse effects. Systemic lignocaine has effective analgesic, anti-inflammatory, and anti-hyperalgesic properties and improves the quality of recovery after surgery.

Material and Methods:

Ninety women scheduled for elective transabdominal hysterectomy under general anesthesia were randomized to receive infusion of lignocaine (1.5 mg/kg over 15 min followed by a 2 mg/kg/h infusion until the end of surgery) (Group 1) or normal saline (10 mL over 15 min followed by infusion 1 mL/kg/h till end of surgery) (Group 2). Standard anesthesia techniques were used in both the groups. The patients received inj. tramadol for postoperative analgesia. Perioperative hemodynamics, extubation variables, postoperative analgesic requirement, and quality of recovery score were evaluated.

Results:

Hemodynamics were maintained in both the groups. Time for extubation was also similar. Demand for first postoperative analgesic was after 70.8 ± 70.4 min (Group 1) and 40.7 ± 30.0 min (Group 2) (P = 0.006). Total tramadol usage was 477.0 ± 133.2 mg (Group 1) and 560.0 ± 115.0 mg (Group 2) (P < 0.001). Return of bowel function was faster in Group 2 compared with Group 1 (37.1 ± 5 vs 41.8 ± 7.4 h, P < 0.001). The median (interquartile range) recovery score (QoR-40) was 184 (178–191) in Group 1 and 178 (171–180) in Group 2 (P < 0.001).

Conclusion:

Perioperative use of intravenous infusion of lignocaine is associated with decreased analgesic requirement postoperatively, and improved quality of recovery score signifying greater patient satisfaction.

Effect of nalbuphine and pentazocine on attenuation of hemodynamic changes during laryngoscopy and endotracheal intubation: A clinical study

Background:

Narcotic drugs have been used to attenuate laryngoscopy and intubation induced circulatory responses, but are not always available due to tough narcotics laws. Nalbuphine a synthetic opioid, free from restrictions has been in use for post-operative pain relief. Hence, we decided to compare nalbuphine and pentazocine for attenuation of hemodynamic effects during larygoscopy and endotracheal intubation in a randomized, double-blind clinical study.

Materials and Methods:

A total of 60 patients (ASA I and II) of either sex, between 18 years and 50 years were given either nalbuphine 0.2 mg/kg (group N, n = 30) or pentazocine 0.5 mg/kg (group P, n = 30) 5 min before induction of general anesthesia. After, induction with thiopentone and endotracheal intubation with succinylcholine balanced anesthesia was maintained with O₂:N₂O, 0.2% halothane and non-depolarizing relaxants for surgical duration. Changes in heart rate (HR), systolic blood pressure (SBP), diastolic pressure, mean arterial pressure, and rate pressure product calculated by HR × SBP were recorded at various time intervals.

Results:

A non-significant fall (P > 0.05) up to 3 min and thereafter a significant rise (P < 0.05) in all the parameters were observed throughout the remaining study period with nalbuphine, whereas a continuous and significant (P < 0.05) rise in these parameters were observed with pentazocine. Maximum rise in both the group was observed immediately after larygoscopy and intubation and these started to return toward the basal values at the end of the study period, but remained above the initial values. (pentazocine > nalbuphine P = <0.01).

Conclusion:

Nalbuphine effectively reduces the tachycardia, hypertension, and cardiac workload associated with laryngoscopy and endotracheal intubation.

Prevention of peri-induction hypertension in preeclamptic patients: a focused review

Many medications have been used to prevent the hypertensive response to the induction of general anesthesia and laryngoscopy in preeclamptic patients, with varying results. In this focused review, we summarize the available data and pharmacologic profiles of these drugs. Several different drug classes may be used safely; however, magnesium bolus, lidocaine, calcium channel antagonists other than nicardipine, and hydralazine are not recommended. Further research is warranted into the hemodynamic impact of varying the induction drug dose or combining different classes of drugs.

Effects of lignocaine on pressor response to laryngoscopy and endotracheal intubation during general anaesthesia in rigid suspension laryngoscopy

OBJECTIVE

This study aimed to compare the effects of topical and systemic lignocaine on the circulatory response to direct laryngoscopy performed under general anaesthesia.

METHODS

Ninety-nine patients over 20 years of age, with a physical status of I-II (classified according to the American Society of Anesthesiologists), were randomly allocated to 3 groups. One group received 5 ml of 0.9 per cent physiological saline intravenously, one group received 1.5 mg/kg lignocaine intravenously, and another group received seven puffs of 10 per cent lignocaine aerosol applied topically to the airway. Mean arterial pressures, heart rates and peripheral oxygen saturations were recorded, and changes in mean arterial pressure and heart rate ratios were calculated.

RESULTS

Changes in the ratios of mean arterial pressure and heart rate were greater in the saline physiological group than the other groups at 1 minute after intubation. Changes in the ratios of mean arterial pressure (at the same time point) were greater in the topical lignocaine group than in the intravenous lignocaine group, but this finding was not statistically significant.

CONCLUSION

Lignocaine limited the haemodynamic responses to laryngoscopy and endotracheal intubation during general anaesthesia in rigid suspension laryngoscopy.

Oral clonidine versus gabapentin as premedicant for obtunding hemodynamic response to laryngoscopy and tracheal intubation

BACKGROUND

We compared the effects of oral clonidine and gabapentin as premedicant in obtunding hemodynamic response to laryngoscopy and intubation in normotensive patients undergoing elective surgery.

METHODS

A total of 100 patients of either sex enrolled in the study were randomly divided into two groups of 50 each. Group A patients received oral clonidine 200 μg and Group B patients received oral gabapentin 900 mg, 90 min prior to induction of anesthesia.

RESULTS

Both groups were matched for age, sex weight and intubation time. Anxiety score and sedation scores before induction were significantly better in Group A as compared with Group B. Heart rate rise was obtunded in Group A except at 1 min, as compared with Group B in which tachycardia persisted even at 3 and 5 min following intubation. Mean arterial pressure was maintained below baseline at all times in Group A as compared with Group B in which significant rise (+7.55%, P < 0.001) was seen at 1 min after intubation.

CONCLUSION

Oral clonidine provided good attenuation of hemodynamic response to laryngoscopy and intubation as compared with oral gabapentin.

The effect of intravenous magnesium sulfate on laryngospasm after elective adenotonsillectomy surgery in children

Background:

Laryngospasm is the protective reflex of tracheobronchial tree against secretions and hemorrhage. This reflex is more prevalent in adenotonsillectomy in the presence of light anesthesia, which can lead to obstruction of airway, complications, and mortality. Different methods have been studied for preventing this complication; however, none of them could reliably prevent it.

Objectives:

The objective was to assess the effect of magnesium sulfate on laryngospasm and coughing after adenotonsillectomy.

Patients and Methods:

Seventy children with three to 12 years of age and ASA classes I and II, who were candidates for adenotonsillectomy, were recruited in this randomized clinical trial. The study group received 15 mg/kg intravenous magnesium sulfate and the control group received 0.9% normal saline with the same volume, 2 minutes after tracheal intubation via intravenous infusion for 20 minutes. After removing the endotracheal tube in the recovery room, the patients were assessed at minutes zero, 15, and 30in terms of laryngospasm and coughing. The assessment was based on four-point scale of severity of these complications and saturation percentage of arterial oxygen in operating and recovery room. After collecting the data, results were analyzed with the SPSS 16 software anda P value < 0.05 was considered statistically significant.

Results:

Laryngospasm was not found in the magnesium sulfate group; however, its incidencewas5.7% in the control group. The incidence rates of coughs were 17.1% and 40% in the magnesium sulfate group and in the control group, respectively, which had no statistically significant differences.

Conclusions:

Intravenous magnesium sulfate with dose of 15 mg/kg could not prevent laryngospasm and coughing after removal of the endotracheal tube in patients undergoing adenotonsillectomy; however, it reduced coughing and laryngospasm in the magnesium sulfate group compared with the control group.

Effect of lidocaine (40 mg) mixed to prevent injection pain of propofol on the intubating conditions and onset time of rocuronium

Background

To analyze how lidocaine 40 mg mixed prevents injection pain of propofol affects the onset time of rocuronium, tracheal intubating conditions and intubation related hemodynamic changes.

Methods

This study consisted of 70 patients with an American Society of Anesthesiologists (ASA) physical status class 1 or 2 for general anesthesia. All the patients were randomly allocated into two groups: propofol 2 mg/kg plus normal saline 2 ml (Group C) and propofol 2 mg/kg plus 2% lidocaine 40 mg (Group L). Each group was administrated intravenously during induction and the patient was intubated 1 minute after an injection of 0.6 mg/kg of rocuronium. The time at disappearance of the first twitch and intubation scores were recorded. Also, blood pressure and heart rate were measured at the baseline, after intravenous injection of propofol, before intubation, and at 0, 1, 2, 3 and 5 minutes after intubation.

Results

There were no significant differences between group C and L (P > 0.05).

Conclusions

40 mg of lidocaine mixed with propofol to prevent injection pain did not affect the onset time of rocuronium, intubating conditions and intubation related hemodynamic changes.

Comparison of esmolol and lidocaine for attenuation of cardiovascular stress response to laryngoscopy and endotracheal intubation in a Ghanaian population

Background:

Direct laryngoscopy and endotracheal intubation always trigger powerful cardiovascular responses. Various attempts have been made to attenuate these responses. The aim of this study was to compare the efficacy and safety of esmolol and lidocaine for suppressing cardiovascular response to laryngoscopy and tracheal intubation in a normotensive African population.

Materials and Methods:

A randomized controlled trial was conducted in 120 adult patients of American Society of Anaesthesiologists (ASA) physical status I or II undergoing various elective surgeries. The patients were randomly divided into three groups of 40 patients in each group - C, L, and E. Group - “C” received no drug (control) as placebo, group -“L” received 1.5 mg kg^-1 preservative free lidocaine and group -“E” received 2 mg kg^-1 esmolol IV 2 min before intubation. Mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before induction as baseline and after tracheal intubation at minute 1, 3, and 5. The patients were randomly allocated to receive either saline (Group C), lidocaine 1.5 mg/kg (Group L), or esmolol 2 mg/kg (Group E) (n = 40, each group). After induction of general anesthesia with thiopental 6 mg/kg and vecuronium 0.12 mg/kg, the test solution was infused 2 min before tracheal intubation. Changes in heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), and rate-pressure product (RPP) were measured before induction of general anesthesia (baseline), 1, 3, and 5 min after tracheal intubation. Patients were also observed for any complications.

Results:

There was a significant increase in HR, SBP, DBP, MAP, and RPP from the base line in control group “C” at 1 min with onward decreases at 3 and 5 min respectively after intubation. Percentage change in hemodynamic variables in groups C, L, and E at 1 min are as follows: HR = 30.45, 26.00, and 1.50%; MAP = 20.80, 15.89, and 10.20%; RPP = 61.44, 40.86, and 11.68%, respectively. Only patients receiving placebo had increased HR, MAP, and RPP values after intubation compared with baseline values (P < 0.05).

Conclusions:

Prophylactic therapy with 2 mg kg^-1 esmolol is more effective and safe for attenuating cardiovascular responses to laryngoscopy and tracheal intubation in a black population.

Intrapulmonary Drug Administration during High Frequency Jet Ventilation

It has previously been demonstrated that high frequency jet ventilation, via transtracheal cricothyroid membrane puncture, can maintain good gas exchange even during cardiopulmonary resuscitation. When the upper airways were filled with fluid, aspiration could be prevented without a cuffed endotracheal tube when respiratory rates of 100/min or higher and an inspiratory time of at least 50% were used. We have also shown that cricothyroid membrane puncture is relatively easy to perform and produces less tracheal damage than a cuffed endotracheal tube.

In one of our studies, cardio-green dye was mixed into the jet using a Y-connector on the proximal end of the angiocath cannula (Figure 1). In two dogs, the distribution of the dye in the lungs was investigated. It was found that nebulized dye was transported by the jet stream to the most distant bronchi which could be observed. On subsequent autopsy, the dye was found in the most peripheral airways.

Efficacy of intravenous lidocaine in prevention of post extubation laryngospasm in children undergoing cleft palate surgeries

A one-year randomized placebo-controlled trial was conducted to study the effectiveness of intravenous lidocaine in the prevention of post extubation laryngospasm in children, following cleft palate surgeries. Children of age three months to six years were randomly assigned into two groups. Group P placebo (saline) and Group L (Lidocaine), 1.5 mg/kg. A sample size of 74 with n = 37 in each group was selected. The anaesthetic procedure was standardized. At the end of the procedure, three minutes after reversal, the study drug, that is, intravenous lidocaine (1.5 mg/kg) or placebo (saline) was administered and two minutes later the child was extubated. Following extubation for 10 minutes, the haemodynamic parameters, that is, pulse, blood pressure, oxygen saturation, severity of coughing, and laryngospasm were noted. The total reduction of laryngospasm and coughing was 29.9% and 18.92% with IV lidocaine. Significant alterations in haemodynamics and oxygen saturation were noted for 10 minutes, following extubation. Hence, intravenous lidocaine 1.5 mg/kg was effective in the prevention of post extubation laryngospasm in children undergoing cleft palate surgeries.

Effectiveness of the timing principle with high-dose rocuronium during rapid sequence induction with lidocaine, remifentanil and propofol

PURPOSE

The main purpose of this study was to examine the effectiveness of the timing principle with 1 mg kg(-1) rocuronium for rapid sequence intubation. As secondary outcomes, propofol and lidocaine with or without remifentanil were examined to note their effects on the cardiovascular responses to laryngoscopy and intubation.

METHODS

Thirty patients were randomly allocated to one of two groups of 15 patients each: a lidocaine-treated group (L) and a lidocaine/remifentanil-treated group (LR). Thirty seconds after lidocaine 1 mg kg(-1) with or without infusion of remifentanil 1 microg kg(-1) min(-1), all patients received a bolus of rocuronium 1 mg kg(-1). Shortly afterwards, patients were given propofol 2-2.5 mg kg(-1). Intubating conditions and cardiovascular responses were observed 60 s after rocuronium. The time to spontaneous recovery of visible train-of-four (TOF) counts of 4 was observed at the thumb during 1.0-1.5% end-tidal sevoflurane and remifentanil anesthesia.

RESULTS

All patients had excellent or good intubating conditions. Hypertension and tachycardia during laryngoscopy were well prevented in group LR, whereas they were significantly observed in group L. The times to reappearance of TOF counts of 4 were comparable in all groups [mean (SD); 63.6 (8.6) min in group L and 63.5 (11.6) min in group LR].

CONCLUSION

Application of the timing principle with 1 mg kg(-1) rocuronium is beneficial for rapid tracheal intubation. Co-administered lidocaine, remifentanil and propofol can definitely suppress cardiovascular responses during laryngoscopy and intubation.

Lidocaine given intravenously improves conditions for laryngeal mask airway insertion during propofol target-controlled infusion

BACKGROUND AND OBJECTIVE

Patient response to laryngeal mask airway insertion during propofol induction depends on many factors. Lidocaine has been used to reduce cardiovascular responses, coughing, and bucking induced by tracheal intubation. The aim of this study was to determine the effects of intravenous lidocaine on laryngeal mask airway insertion conditions during the induction of anaesthesia with propofol target-controlled infusion.

METHODS

Eighty patients, 16-54 years of age, weighing between 45 and 100 kg, who underwent minor surgery, were randomly divided into two groups (the lidocaine and control groups). Anaesthesia was induced with propofol target-controlled infusion at a target plasma concentration of 6 microg ml. The lidocaine group received 1.5 mg kg of lidocaine 50 s after starting target-controlled infusion and the control group received an equivalent volume of saline. Laryngeal mask airways were inserted when propofol effect-site concentrations reached 2.5 microg ml. Laryngeal mask airway insertion conditions (mouth opening, gagging, coughing, movements, laryngospasm, overall ease of insertion, and hiccups) were assessed, and haemodynamic responses were monitored for 3 min after laryngeal mask airway insertion.

RESULTS

No significant differences were observed between the two groups in terms of haemodynamic responses. However, the lidocaine group showed lower incidences of coughing (5 vs. 22.5%), gagging (25 vs. 55%), and laryngospasm (2.5 vs. 17.5%) (P < 0.05).

CONCLUSION

Pretreatment with intravenous lidocaine 1.5 mg kg during induction with propofol target-controlled infusion improves laryngeal mask airway insertion conditions.

Effect of intravenous lidocaine on heart rate, systolic arterial blood pressure and cough responses to endotracheal intubation in propofol-anaesthetized dogs

OBJECTIVE

To evaluate the effect of intravenous lidocaine on coughing and variations in heart rate (HR) and systolic arterial pressure (SAP) at endotracheal intubation in propofol-anaesthetized dogs.

STUDY DESIGN

Prospective, randomized, blinded clinical study.

ANIMALS

Eighty dogs, ASA grades I/II.

METHODS

Dogs were randomly assigned to one of two treatments, with dogs in the lidocaine group receiving 1 mg kg(-1) lidocaine intravenously and those in the saline group receiving 0.05 mL kg(-1) saline intravenously before induction of anaesthesia with up to 6.5 mg kg(-1) propofol intravenously. An electrocardiogram was recorded continuously. Heart rate was calculated and SAP (using Doppler ultrasonic flow detection) was recorded at the following time points: pre-treatment, following lidocaine or saline administration, before and after intubation. The occurrence, number and strength of coughs were recorded. Systolic arterial pressure and HR were compared using one-sample t-tests to examine whether SAP and HR changed with test drug administration or following intubation. The number of coughs was compared between groups using t-tests. A cross tabulation and chi-square or Fisher's exact test was used to compare proportions of dogs that coughed and intensity of coughing in each group. The level of significance was set at p < 0.05.

RESULTS

Heart rate did not change in either group. Systolic arterial blood pressure increased following intubation in both the lidocaine (p = 0.003) and saline groups (p = 0.001). There was no difference in the increase in SAP or in the number or intensity of coughs at intubation between groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous lidocaine had no effect on the occurrence or intensity of coughing or on changes in SAP at endotracheal intubation in dogs anaesthetized with propofol. The use of 1 mg kg(-1) lidocaine intravenously before intubation in dogs to attenuate cough and the pressor response was not supported.

Effects of esmolol, lidocaine and fentanyl on haemodynamic responses to endotracheal intubation: a comparative study

BACKGROUND AND OBJECTIVE

Predicting the haemodynamic changes that may result in myocardial ischaemia for patients undergoing laryngoscopy and tracheal intubation will help to avoid events that trigger ischaemia and allow immediate treatment. The objective of this study was to compare the effects of esmolol with those of lidocaine (lignocaine) and fentanyl on prevention of tachycardia and hypertension caused by endotracheal intubation.

METHODS

This was a prospective, randomised, double-blind study. The study was conducted at the Adnan Menderes University Hospital in Aydin, Turkey and involved 120 patients of American Society of Anesthesiologists physical status I or II aged 20-50 years. The patients were randomised into four equal groups. The control group (group C) received dextrose 5% 5 mL, the esmolol group (group E) received esmolol 1.5 mg/kg, the fentanyl group (group F) received fentanyl 1 microg/kg and the lidocaine group (group L) received lidocaine 1.5 mg/kg 2 minutes before endotracheal intubation. Heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were recorded before and after induction of anaesthesia, immediately after intubation, and 1, 3, 5, 7 and 10 minutes after intubation.

RESULTS

Compared with control, HR decreased significantly in group E after induction, immediately after intubation and 1 minute after intubation (p < 0.0083). In group F there was an increase in MAP immediately after intubation, but the increase was less than in other groups. Compared with control, RPP decreased significantly in groups E and F after induction, immediately after intubation and 1 minute after intubation (p < 0.0083). RPP was significantly lower in group E than in controls and group L 3 minutes after intubation (p < 0.0083), and it was significantly lower in group F than in controls 10 minutes after intubation (p < 0.0083).

CONCLUSION

It can be concluded that administration of esmolol 1.5 mg/kg 2 minutes before intubation prevents tachycardia and an increase in RPP caused by laryngoscopy and tracheal intubation, and can be beneficial when administered before laryngoscopy and tracheal intubation in patients with tachycardia.

The effects of intravenous lignocaine on haemodynamics and seizure duration during electroconvulsive therapy

Electroconvulsive therapy (ECT) is commonly associated with acute hyperdynamic cardiovascular responses, and we hypothesize that intravenous lignocaine can blunt this response. We have measured the effect of lignocaine 1.5 mg/kg i.v. on heart rate and mean arterial pressure during electroconvulsive therapy. Furthermore, we also assessed seizure duration using both the cuff method and two-lead electroencephalography. We studied 25 patients using a randomized, double-blind, placebo-controlled crossover study design. Patients in the control group were given intravenous saline 0.075 ml/kg, and those in the lignocaine group were given intravenous lignocaine 2% 1.5 mg/kg, and this treatment was conducted one minute before intravenous propofol 1.5 mg/kg to induce unconsciousness. Succinylcholine 1.5 mg/kg was then administered intravenously and electrical stimulation was administered after fasciculation. Measurements were taken at the baseline, prior to succinycholine, prior to electroconvulsive therapy and at the peak response after electroconvulsive therapy. Intravenous lignocaine significantly reduced the increases in heart rate after electroconvulsive therapy, as compared with the placebo. The use of intravenous lignocaine was, however, associated with a remarkably shortened seizure duration. Due to the reduction in seizure duration, routine administration of intravenous lignocaine may not be advisable since it may interfere with the psychotherapeutic efficacy of electroconvulsive therapy. However, intravenous lignocaine medication for electroconvulsive therapy is potentially useful for reducing tachycardia in high-risk patients and reducing the severity of propofol injection pain in comparison with a placebo.

Rapid sequence induction: a national survey of practice

We performed a national postal survey exploring anaesthetists' practice in rapid sequence induction. All respondents used pre-oxygenation, although the technique employed, and its reliability, varied. Thiopental and succinylcholine, given after waiting for signs of loss of consciousness, were the most widely used drugs for rapid sequence induction. Propofol and rocuronium were used by more than a third of respondents, and most respondents (75%) also routinely administered an opioid. Cricoid pressure was used universally but the practice of its application varied widely. The commonest aids used if intubation was difficult were the gum elastic bougie, the long laryngoscope blade and the laryngeal mask. After failed intubation, approximately half of respondents would maintain the supine position. Failure to intubate at rapid sequence intubation had been seen by 45% of respondents but harm was uncommon. In contrast, 28% had seen regurgitation, which frequently led to considerable harm and to three deaths. In spite of this, practice of a failed intubation drill was uncommon (15%) and anaesthetic assistants were rarely known to practice application of cricoid pressure. Consultants were less likely than trainees to use rocuronium as a muscle relaxant, and more likely to choose morphine if administering an opioid. They were less likely to practice a failed intubation drill. Other aspects of practice varied little between grades. This survey suggests that many anaesthetists do not follow best practice when performing a rapid sequence induction.

In patients with head injury undergoing rapid sequence intubation, does pretreatment with intravenous lignocaine/lidocaine lead to an improved neurological outcome? A review of the literature

It is well known that laryngeal instrumentation and endotracheal intubation is associated with a marked, transient rise in intracranial pressure (ICP). Patients with head injury requiring endotracheal intubation are considered particularly at risk from this transient rise in ICP as it reduces cerebral perfusion and thus may increase secondary brain injury. The favoured method for securing a definitive airway in this patient group is by rapid sequence intubation (RSI). In the United States the Emergency Airway Course teaches emergency physicians to routinely administer intravenous lidocaine as a pre treatment for RSI in this patient group in an attempt to attenuate this rise in ICP. A literature search was carried out to identify studies in which intravenous lidocaine was used as a pretreatment for RSI in major head injury. Any link to an improved neurological outcome was also sought. Papers identified were appraised in the manner recommended by the evidence based medicine group to ensure validity. There were no studies identified that answered our question directly and, furthermore, it is our belief that no such study, at present, exists in the literature. Six valid papers were found, which individually contained elements of the question posed and these are presented in a narrative and graphic form. There is currently no evidence to support the use of intravenous lidocaine as a pretreatment for RSI in patients with head injury and its use should only occur in clinical trials.

The efficacy of esmolol versus lidocaine to attenuate the hemodynamic response to intubation in isolated head trauma patients

OBJECTIVE

To assess the effect of esmolol vs lidocaine to attenuate the detrimental rise in heart rate and blood pressure during intubation of patients with isolated head trauma.

METHODS

This was a prospective, double-blind, randomized study, performed at an urban, county teaching emergency department. Participants were 30 patients with isolated head trauma. Each underwent a standardized intubation protocol including esmolol or lidocaine, both at 2 mg/kg.

RESULTS

Esmolol was used in 16 patients and lidocaine in 14. Mechanisms of injury included 12 assaults, 6 motor vehicle collisions, 6 falls, 4 auto-vs-pedestrian crashes, and 2 bicycle incidents. Mean ethanol level was 0.116+/-0.133 SD (range 0-0.482). Mean Glasgow Coma Scale (GCS) score was 7.9+/-4.0 SD. Cranial computed tomography (CT) hemorrhagic findings included 9 subdural/epidural hematomas, 6 cortex hemorrhages, and 2 multi-hemorrhages. Eleven patients received surgical intervention: 9 patients received a craniotomy, and 2 a ventricular catheter. The 2-minute time interval around intubation was used to assess each drug's efficacy. The mean difference change between groups for heart rate was 4.0 beats/min (95% CI = -17.7 to 9.7 beats/min), for systolic blood pressure was 1.3 mm Hg (95% CI = -27.8 to 30.4 mm Hg), and for diastolic blood pressure was 2.6 mm Hg (95% CI = -27.1 to 21.9 mm Hg). The power of this study was 90% to detect a 20-beat/min difference in heart rate, a 35-mm Hg difference in systolic blood pressure, and a 20-mm Hg difference in diastolic blood pressure.

CONCLUSIONS

Esmolol and lidocaine have similar efficacies to attenuate moderate hemodynamic response to intubation of patients with isolated head trauma.

Combined diltiazem and lidocaine reduces cardiovascular responses to tracheal extubation and anesthesia emergence in hypertensive patients

PURPOSE

Hypertensive patients exhibit exaggerated cardiovascular responses to tracheal extubation. This study was undertaken to compare the efficacy of combined diltiazem and lidocaine with each drug alone in suppressing the hemodynamic changes during tracheal extubation.

METHODS

Sixty hypertensive patients (ASA II), defined as systolic blood pressure > 160 mmHg and/or diastolic blood pressure > 95 mmHg (WHO), undergoing elective orthopedic surgery received, in a randomized, double-blind manner, 0.2 mg x kg(-1) diltiazem, 1.0 mg x kg(-1) lidocaine, or 0.2 mg x kg(-1) diltiazem plus 1.0 mg x kg(-1) lidocaine (n=20 of each) i.v. before tracheal extubation. Changes in heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before and after tracheal extubation.

RESULTS

Hemodynamic changes during tracheal extubation were less in patients receiving diltiazem plus lidocaine than in those receiving diltiazem or lidocaine as a sole medicine (RPP; 10322 +/- 1674 (combined) vs 11532 +/- 1802 (diltiazem), 15388 +/- 2050 (lidocaine), mean +/- SD, P < 0.05).

CONCLUSION

Combined diltiazem and lidocaine is more effective prophylaxis than diltiazem or lidocaine alone for attenuating the cardiovascular responses to tracheal extubation and emergence from anesthesia in hypertensive patients.

Diltiazem-lidocaine combination for the attenuation of cardiovascular responses to tracheal intubation in hypertensive patients

PURPOSE

Hypertensive patients are prone to haemodynamic changes after laryngoscopy and tracheal intubation. This study was undertaken to compare the efficacy of a combination of diltiazem and lidocaine with that of each drug alone for suppressing the cardiovascular responses to tracheal intubation.

METHODS

Sixty hypertensive patients (ASA II), defined as systolic blood pressure > 160 mmHg and/or diastolic blood pressure > 95 mmHg (World Health Organization), undergoing elective surgery received, in a randomized, double-blind manner, 0.3 mg.kg-1 diltiazem, 1.5 mg.kg-1 lidocaine, or 0.3 mg.kg-1 diltiazem plus 1.5 mg.kg-1 lidocaine i.v. (n = 20 of each) before the initiation of laryngoscopy. Anaesthesia was induced with 5 mg.kg-1 thiopentone i.v., and tracheal intubation was facilitated with 2 mg.kg-1 succinylcholine i.v. after precurarization with 0.02 mg.kg-1 vecuronium i.v. Changes in heart rate (HR), mean arterial pressure (MAP) and rate-pressure product (RPP) were measured before and at immediate, 1, 2, 3, 5 and 10 min after tracheal intubation.

RESULTS

The inhibitory effects of diltiazem-lidocaine combination on cardiovascular responses to tracheal intubation was greater than those of diltiazem or lidocaine as a sole medicine (RPP; 10,602 +/- 1448 (combination) vs 11,787 +/- 1345 (diltiazem), 15,428 +/- 1756 (lidocaine), mean +/- SD, P < 0.05).

CONCLUSION

Prophylactic therapy with diltiazem-lidocaine combination is more effective than diltiazem or lidocaine alone for attenuating the cardiovascular changes associated with tracheal intubation in hypertensive patients.

Reduction of cardiovascular response to endotracheal intubation in normotensive patients by urapidil

PURPOSE

Urapidil is an antihypertensive drug with actions of α₁-receptor blockade and 5-HT_1A (5-hydroxytryptamine) receptor stimulation. Although many agents have been used to attenuate the cardiovascular response to endotracheal intubation, few of them are related to urapidil. This study was done to evaluate the effects of urapidil on reducing the cardiovascular response to intubation.

METHODS

In this randomized, double-blind, placebo-controlled study, 30 ASA I-II adult surgical patients without cardiovascular disease were divided into two groups of 15 each, receiving either an i.v. bolus of 0.6 mg·kg^-1 urapidil 5 min before intubation or an equivalent volume of saline as control. The heart rate and the systolic and diastolic blood pressure were determined intermittently for 5 min before and 10 min after intubation. The mean blood pressure, product of systolic blood pressure and heart rate, and coefficient of variation (CV) of these variables around intubation were calculated.

RESULTS

Urapidil had no effects on the heart rate (P>0.05), could effectively attenuate the increases in the diastolic and mean arterial pressures (P<0.05) caused by intubation, but had a weak effect on the systolic pressure (P>0.05) and its product with heart rate. In addition, the CV of the diastolic pressure and mean arterial pressure was greater (P<0.05) in the urapidil group than in the control group, which meant that the induction procedure with urapidil was not more stable than that when saline was used as placebo.

CONCLUSION

The effects of urapidil on reducing the cardiovascular response to intubation are mild when uradipil is used 5 min before intubation. As urapidil mainly decreases diastolic blood pressure, an important determinant of cardiac blood supply, and it makes systolic, diastolic, and mean blood pressure fluctuate strongly during induction, we should be alert about its latent detrimental effect on patients, especially those with ischemic heart disease.

Effects of intravenous lidocaine and/or esmolol on hemodynamic responses to laryngoscopy and intubation: a double-blind, controlled clinical trial

STUDY OBJECTIVES

To evaluate the efficacy of intravenous lidocaine and two doses of esmolol for attenuating the cardiovascular responses to laryngoscopy and intubation, and to assess whether a combination of both drugs is more effective than either drug alone.

DESIGN

Randomized, prospective, double-blind, placebo-controlled study.

SETTING

University hospital.

PATIENTS

90 ASA status I and II normotensive women scheduled for elective gynecologic procedures with general anesthesia.

INTERVENTIONS

Induction of anesthesia was standardized for all patients. The first group received lidocaine 1.5 mg/kg (Group LID); the second and third groups received esmolol 1 mg/kg and 2 mg/kg, respectively (Groups E1 and E2, respectively); the fourth group received lidocaine 1.5 mg/kg and esmolol 1 mg/kg (Group LID-E1); the fifth group received lidocaine 1.5 mg/kg and esmolol 2 mg/kg (Group LID-E2); the sixth group received saline as a placebo (Group PLAC).

MEASUREMENTS AND MAIN RESULTS

Systolic blood pressure and heart rate (HR) were recorded before induction, before injection of the first test drug, immediately before laryngoscopy, and 1, 2, and 5 minutes following intubation. Duration of laryngoscopy was recorded. Only patients receiving placebo had increased HR values after intubation compared with baseline values (p < 0.05). The proportion of patients with a maximum HR exceeding 90 beats/min was significantly higher in the placebo group (8 of 15 patients) than in both esmolol groups (E1 2 of 15; E2 2 of 15) (p < 0.05). Systolic blood pressure values after tracheal intubation did not differ among groups except for those receiving the combinations of lidocaine and esmolol, and they had significantly lower blood pressure (BP) values compared with placebo (p < 0.05).

CONCLUSIONS

Esmolol 1 to 2 mg/kg is reliably effective in attenuating HR response to tracheal intubation. Neither of the two doses of esmolol tested nor that of lidocaine affected the BP response. Only the combination of lidocaine and esmolol attenuated both HR and BP responses to tracheal intubation.

Esmolol blunts the haemodynamic responses to tracheal intubation in treated hypertensive patients

PURPOSE

To compare the ability of different bolus doses of esmolol to blunt the haemodynamic effects of laryngoscopy and tracheal intubation in treated hypertensive patients.

METHODS

In this randomised, double-blind placebo controlled study, 45 ASA II patients, treated for essential hypertension with drugs other than beta blockers, were divided into three groups of 15 patients each. Patients in different groups either received 20 ml normal saline (Group P), or 100 mg esmolol (Group E100) or 200 mg esmolol (Group E200) as a single bolus intravenous dose before laryngoscopy and intubation. Systolic, diastolic and mean arterial pressure and heart rate were monitored for up to 10 min following intubation and were compared with respective basal readings as well as across groups.

RESULTS

Esmolol alone reduced systolic arterial pressure (P < 0.01 in Group E100 and P < 0.001 in Group E200) and heart rate (P < 0.001). Though there was an increase in arterial pressure and heart rate in the control group, esmolol 100 mg maintained arterial pressure and heart rate at levels comparable to basal values throughout the study (P > 0.05). Patients receiving esmolol 200 mg had lower values (P < 0.001) than their basal readings during most of the post-intubation study period.

CONCLUSION

Esmolol 100 mg given as bolus, is effective as well as safe in blunting the haemodynamic responses to laryngoscopy and tracheal intubation in treated hypertensive patients.

Lignocaine to aid the insertion of the laryngeal mask airway with thiopentone. A comparison between topical and intravenous administration

Conditions for insertion of a laryngeal mask airway in 90 unpremedicated adult were patients were assessed in a randomised, single-blinded trial. Each patient received fentanyl 1 microgram.kg-1 and thiopentone 5 mg.kg-1, and this was preceded either by lignocaine 0.5 mg.kg-1 intravenously (group 1), lignocaine 1.5 mg.kg-1 intravenously (group 2) or 40 mg of topical lignocaine spray to the posterior pharyngeal wall (group 3). Conditions for laryngeal mask airway insertion were recorded. The group receiving topical lignocaine had a lower incidence of laryngospasm (p < 0.05), required fewer attempts for successful insertion of the laryngeal mask (p < 0.05) and coughed or gagged less frequently than either group receiving lignocaine intravenously (p > 0.05). Overall, the conditions for laryngeal mask airway insertion were better in the topical group (p < 0.05). There were no significant differences in haemodynamic response and apnoea between the three groups. Topical lignocaine spray prior to thiopentone provides conditions for insertion of a laryngeal mask that are superior to those provided by lignocaine and thiopentone intravenously.

Topical lignocaine and thiopentone for the insertion of a laryngeal mask airway; a comparison with propofol

We assessed conditions for insertion of a laryngeal mask airway in 90 unpremedicated adult patients who received either thiopentone 5 mg.kg-1 preceded by 40 mg of topical lignocaine spray to the posterior pharyngeal wall or propofol 2.5 mg.kg-1 alone in a randomised, single-blinded trial. All patients received fentanyl 1 microgram.kg-1. Gagging, coughing and laryngospasm following laryngeal mask insertion were graded and haemodynamic data and apnoea times were recorded. There were no significant differences between the two groups with regard to the incidence of gagging, coughing and laryngospasm, but the apnoea time was significantly less in the thiopentone group (p < 0.005). The decrease in systolic and diastolic blood pressure, following induction and the insertion of a laryngeal mask with propofol was significantly greater than following thiopentone (p < 0.05--systolic, p < 0.01--diastolic). We conclude that thiopentone preceded by topical lignocaine spray provides conditions for insertion of a laryngeal mask equal to those of propofol, with more haemodynamic stability and a shorter period of apnoea.

Comparison of propofol versus thiopentone with midazolam or lidocaine to facilitate laryngeal mask insertion

PURPOSE

To assess the ease of insertion of laryngeal mask airway (LMA) comparing propofol with lidocaine or midazolam followed by thiopentone and compare the costs with each technique.

METHODS

One hundred and fifty ASA 1 or 2 patients equally divided into three groups scheduled for elective surgery were recruited into this prospective, single blind, randomized, parallel groups study. Anaesthetic induction was achieved with 1 microgram.kg-1 fentanyl i.v. followed by either 2.5 mg.kg-1 propofol (group P), or a sequence of 1.5 mg.kg-1 lidocaine and 5 mg.kg-1 thiopentone (group LT), or midazolam 0.1 mg.kg-1 and, three minutes later, 5 mg.kg-1 thiopentone (group MT). The LMA was inserted by the blinded anaesthetist who assessed and graded the conditions for LMA insertion and noted any adverse responses (i.e., inadequate jaw relaxation, gagging, coughing, limb or head movement, hiccough and laryngospasm). Conditions were considered "excellent" if there were no adverse responses, and "satisfactory" if such a response was mild and transient.

RESULTS

Excellent or satisfactory conditions were observed in 48 (96%) patients in the midazolam-thiopentone group, 46 (92%) in the propofol group, and 34 (68%) in the lidocaine-thiopentone group (P = 0.0001). The incidence of gagging (P = 0.042), limb movement (P = 0.031), and laryngospasm (P = 0.0001) was higher in the lidocaine-thiopentone group.

CONCLUSIONS

With the above doses, a fentanyl-midazolam-thiopentone combination which is about 35% less expensive than fentanyl-propofol, provides equally good conditions for the insertion of LMA.

Controlling the hemodynamic response to laryngoscopy and endotracheal intubation

The hemodynamic response to the stress of laryngoscopy and endotracheal intubation does not present a problem for most patients. However, patients with cardiovascular or cerebral disease may be at increased risk of morbidity and mortality from the tachycardia and hypertension resulting from this stress. These hemodynamic effects gained notice after the introduction and use of muscle relaxants, such as curare and succinylcholine, for endotracheal intubation at the time of anesthesia induction. A variety of anesthetic techniques and drugs are available to control the hemodynamic response to laryngoscopy and intubation. The method or drug of choice depends on many factors, including the urgency and length of surgery, choice of anesthetic technique, route of administration, medical condition of the patient, and individual preference. The possible solutions number as many as the medications and techniques available and depend on the individual patient and anesthesia care provider. This paper reviews these medications and techniques to guide the clinician in choosing the best methods.

[Prevention of increase of blood pressure and intracranial pressure during endotracheal intubation in neurosurgery: esmolol versus lidocaine]

OBJECTIVES

To compare the preventive effects of esmolol and lidocaine on the increase in mean arterial pressure (MAP) and intracranial pressure (ICP) during endotracheal intubation in neurosurgery.

STUDY DESIGN

Comparative, randomised, double-blind study.

PATIENTS

Twenty-two patients, physical status ASA I or II, undergoing neurosurgery, and randomised into two groups (esmolol group and lidocaine group).

METHODS

After induction of anaesthesia with thiopentone, vecuronium, fentanyl and isoflurane, one group received iv esmolol 1.5 mg.kg-1 and the other iv lidocaine 1.5 mg.kg-1, 130 sec before endotracheal intubation. The MAP measured with a radial catheter, the ICP obtained with a lumbar subarachnoid catheter and the cerebral perfusion pressure (CPP, calculated from MAP and ICP) were assessed before induction of anaesthesia, before esmolol or lidocaine injection, and before intubation, during the maximal change in MAP, as well as 2 and 5 minutes after intubation.

RESULTS

The time course of MAP, ICP and CCP were similar throughout the study in the two groups, with a significant decrease (P < 0.05) of the CPP from 92 +/- 12 to 62 +/- 8 mmHg after esmolol, and from 96 +/- 12 to 68 +/- 15 mmHg after lidocaine. Following intubation, CPP increased significantly (P < 0.05) to 99 +/- 23 mmHg after esmolol and to 99 +/- 17 mmHg after lidocaine. The ICP increased also significantly (P < 0.05) after intubation from 11 +/- 6 to 17 +/- 10 mmHg in the esmolol group, and from 10 +/- 6 to 16 +/- 9 mmHg in the lidocaine group.

CONCLUSIONS

Esmolol or lidocaine as an iv bolus of 1.5 mg.kg-1 before laryngoscopy and intubation do not completely prevent the increase in MAP and ICP.

A comparison of the stress response to laryngoscopy. The Macintosh versus the McCoy blade

The cardiovascular changes and catecholamine concentrations were compared in 20 patients before and after laryngoscopy with either the Macintosh or the McCoy laryngoscope blades. Following induction with fentanyl and thiopentone and muscle relaxation with vecuronium the vocal cords were visualised for 10 s with either the Macintosh or McCoy blade, chosen at random. Heart rate, arterial blood pressure and plasma noradrenaline and adrenaline concentrations were measured before, and at, laryngoscopy, and 1, 3 and 5 min later. There was a significant increase in both heart rate (33%) and arterial blood pressure (27%) after laryngoscopy using the Macintosh blade (p < 0.01). Use of the McCoy blade did not result in any significant change in either heart rate or arterial blood pressure. There was a slight increase (p > 0.05) in plasma noradrenaline concentrations using the Macintosh blade which persisted for 5 min after laryngoscopy. This was not observed with the McCoy blade. There was no change in plasma adrenaline concentrations with either blade during the 5 min after laryngoscopy when compared to the values before laryngoscopy. It is concluded that the stress response to laryngoscopy is less marked with the use of the McCoy blade and is probably due to a reduction in the force necessary to obtain a clear view of the larynx.

Facilitation of laryngeal mask insertion. Effects of lignocaine given intravenously before induction with propofol

The effects of pretreatment with lignocaine administered intravenously on the insertion of the laryngeal mask airway were investigated in 80 unpremedicated, ASA 1 or 2, adult day-case patients in a randomised, double-blind, placebo-controlled trial. Patients received either intravenous lignocaine 1.5 mg.kg-1 or an equivalent volume of sodium chloride 0.9%. Induction of anaesthesia was achieved with propofol given via a syringe driver at a fixed rate of 600 ml.h-1 until the patient dropped a weighted syringe. No opioid or sedative drugs were given prior to induction. Pain on injection of propofol was recorded. Jaw opening, ease of insertion of the laryngeal mask, coughing, gagging and airway patency were all scored on three-point scales immediately after mask insertion re-attempted. This cycle was continued until success was achieved and the number of such cycles recorded. There were no differences between the lignocaine and control groups with respect to induction dose of propofol, degree of jaw opening, or amount of gagging. Laryngeal mask insertion was facilitated by pretreatment with lignocaine administered intravenously, without an alteration in induction dose of propofol (p < 0.05). Coughing and airway obstruction were both significantly reduced by pretreatment with lignocaine, as was the incidence of failure of insertion requiring deepening of anaesthesia (p < 0.05).

Prophylactic lidocaine use preintubation: a review

This article is a review of the use of prophylactic lidocaine as a preintubation medication. Intubation is associated with a cardiovascular response of elevated blood pressure and pulse, cough reflexes, occasional dysrhythmias, increased intracranial pressure, and increased intraocular pressure. In patients with atherosclerotic heart disease, potential intracranial lesions, and potential penetrating eye injuries, these responses to intubation are of greater risk. Various studies have reviewed the effect of lidocaine to blunt these responses. It is agreed that lidocaine blunts cough reflexes and dysrhythmias. Some studies note a response of lidocaine in blunting rises in pulse, blood pressure, intracranial and intraocular pressure. No studies document any harmful effects of prophylactic lidocaine given preintubation. A dose of prophylactic lidocaine of 1.5 mg/kg given intravenously 3 minutes before intubation is optimal. For suctioning of intubated patients, lidocaine can be given endotracheally in a 5-6 mg/kg dose diluted in 6 cc via simple administration at the entrance to the endotracheal tube.

Emergency management of the airway outside the operating room

Successful emergency airway intervention incorporates the anaesthetist's basic skills in airway management with the knowledge of the special nature of the clinical problems that arise outside the operating room. While a thorough but rapid evaluation of the key anatomical and physiological factors of an individual patient may result in an obvious choice for optimal management, clinical problems often arise in which there is not an evident "best approach." In these less clear-cut situations, the anaesthetist may do well to employ those techniques with which she/he has the greatest skills and experience. At times, however, some degree of creative improvisation is required to care for an especially difficult problem.

Lidocaine effects on the laryngeal chemoreflex, mechanoreflex, and afferent electrical stimulation reflex

The use of lidocaine hydrochloride as either a topical or intravenous agent has become a common practice for minimizing laryngospasm and the reflex cardiovascular effects resulting from upper airway manipulation. The efficacy and mechanism of action of lidocaine for this purpose remain unclear. We evaluated the effect of lidocaine on the laryngeal chemoreflex (LCR), mechanoreflex (LMR), and superior laryngeal nerve electrical stimulation adductor reflex (SLN-ESAR) in piglets. Cardiopulmonary responses were used to assess LCR and LMR. Latency following SLN stimulation was used to assess SLN-ESAR. Intravenous lidocaine hydrochloride at 3 mg/kg produced no suppression of the LCR, LMR, or latency (SLN-ESAR onset latency before lidocaine 11.7 +/- 0.7 milliseconds, after lidocaine 12.2 +/- 0.5 milliseconds; peak latency before lidocaine 13.2 +/- 0.2 milliseconds, after lidocaine 13.4 +/- 0.4 milliseconds). Topically applied lidocaine at the same dose eliminated both LCR and LMR responses in all animals, with return of reflex responses 15 minutes after application. No effect on the SLN-ESAR was seen with application of topical lidocaine. This study supports topical lidocaine as a suppressant of laryngeal mucosal neuroreceptors without central neural reflex effects. Intravenous lidocaine did not affect peripheral neuroreceptors, nor did it significantly affect the latency of the SLN-ESAR neural reflex arc. Intravenous and topical lidocaine differ in mechanism of action and efficacy with regard to modulation of reflex effects induced by laryngeal stimulation.

Effects of nicardipine on the circulatory responses to tracheal intubation in normotensive and hypertensive patients

This study was undertaken to examine the effects of nicardipine on circulatory responses to laryngoscopy and tracheal intubation in normotensive (n = 39) and hypertensive (n = 36) patients. Laryngoscopy and tracheal intubation were performed after induction of anaesthesia with thiamylal, followed by administration of intravenous saline or nicardipine 20 or 30 micrograms.kg-1 and suxamethonium. Blood pressure and heart rate were recorded, and rate-pressure product was calculated. Nicardipine 20 and 30 micrograms.kg-1 prevented the increase in mean arterial pressure after intubation in normotensive and hypertensive patients (p less than 0.01 compared with saline). The changes in heart rate after intubation were significantly greater in normotensive patients than in hypertensive patients when 20 or 30 micrograms.kg-1 of nicardipine was given (p less than 0.05 and p less than 0.01 respectively). Rate-pressure product increased significantly (p less than 0.01) after intubation in normotensive patients whether nicardipine was administered or not, but the increase was suppressed completely by nicardipine 20 or 30 micrograms.kg-1 in hypertensive patients. We conclude that nicardipine is effective in preventing the circulatory responses to laryngoscopy and tracheal intubation in hypertensive patients.