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Effects of alfentanil and lidocaine on the hemodynamic responses to laryngoscopy and tracheal intubation.

This study was undertaken to determine whether lidocaine and/or alfentanil can effectively abolish or attenuate the increase in mean arterial pressure (MAP), heart rate (HR), and rate pressure product (RPP) associated with rapid sequence induction of anesthesia. Sixty patients were randomly divided into four groups. Group 1 received saline 10 ml, group 2 received lidocaine 2 mg/kg, group 3 received alfentanil 15 micrograms/kg, and group 4 received alfentanil 30 micrograms/kg. All patients were induced with sodium thiopental 4 mg/kg and succinylcholine 1.5 mg/kg to facilitate tracheal intubation. The study drug was given after sodium thiopental was administered, and the investigator was blinded to it. Blood pressure (BP) and HR were recorded at the following times: before induction; after induction but before laryngoscopy and intubation; and 1, 3, and 5 minutes after intubation. Alfentanil 15 and 30 micrograms/kg given in rapid sequence fashion with thiopental and succinylcholine effectively blunted the hemodynamic responses to laryngoscopy and tracheal intubation. Lidocaine 2 mg/kg and saline were found to be ineffective in blunting these same responses.

Adult↗

Lidocaine inhalation attenuates the circulatory response to laryngoscopy and endotracheal intubation.

STUDY OBJECTIVE: To evaluate the effect of lidocaine inhalation on the circulatory response to direct laryngoscopy and endotracheal intubation. DESIGN: Prospective, randomized study. SETTING: Operating theater at a public hospital. PATIENTS: Eighty patients (ASA physical status I and II ages 25 to 45 years) scheduled for major abdominal surgery. INTERVENTIONS: In the first stage, 40 patients were randomly assigned to receive inhalation of either lidocaine 40 mg or a 0.9% solution of sodium chloride (placebo). In the second stage, the next 20 consecutive patients received inhalation of lidocaine 120 mg, and another 20 consecutive patients received intravenous (IV) lidocaine 1 mg/kg. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure rose significantly in the i.v. lidocaine group (21.2 mmHg; p < 0.05), the saline inhalation group (29.2 mmHg; p < 0.05), and the lidocaine 40 mg inhalation group (22.9 mmHg; p < 0.05), but not in the lidocaine 120 mg inhalation group (10.1 mmHg). The heart rate (HR) response to intubation with lidocaine inhalation was dose dependent. In the saline inhalation group, HR increased by 15.6 beats per minute (bpm) (p < 0.05); in the lidocaine 40 mg inhalation group, HR increased by 9.1 bpm (p < 0.05); and in the lidocaine 120 mg inhalation group, HR increased by only 3.1 bpm. CONCLUSION: Inhalation of lidocaine 120 mg prior to induction of anesthesia is an effective, safe, and convenient method to attenuate the circulatory response to laryngoscopy and endotracheal intubation.

Adult↗

Hemodynamic effects during induction, laryngoscopy, and intubation with eltanolone (5 beta-pregnanolone) or propofol. A study in ASA I and II patients.

STUDY OBJECTIVE: To evaluate the cardiovascular changes following induction of anesthesia, laryngoscopy, and intubation in patients receiving a bolus dose of either eltanolone or propofol. DESIGN: Randomized, controlled, blind, prospective clinical study. SETTING: General operating theaters of a university hospital. PATIENTS: 40 ASA status I and II patients scheduled for elective surgery. INTERVENTIONS: Patients were premedicated with oral temazepam 20 mg. Anesthesia was induced with either eltanolone 0.58 mg/kg or propofol 1.7 mg/kg, neuromuscular blockade was achieved with vecuronium 0.1 mg/kg, and anesthesia was maintained with enflurane 0.5% to 1.0% in nitrous oxide (67%). MEASUREMENTS AND MAIN RESULTS: Blood pressure was measured using an automatic oscillometric technique, heart rate (HR) was derived from the ECG, oxygen saturation was measured by pulse oximetry, and cardiac output (Q) was measured by a thoracic bioimpedance technique. Induction of anesthesia with either drug, eltanolone or propofol, decreased arterial systolic (SAP) and diastolic (DAP) blood pressure, Q, and stroke volume (SV). HR increased. Systemic vascular resistance (SVR) was unaltered. After laryngoscopy and intubation, SAP and DAP increased secondary to an increase in SVR. HR also increased; SV decreased in patients receiving eltanolone. Side effects (e.g., apnea occurring for more than 30 seconds, involuntary movements, limb hypertonus) occurred at a similar incidence with both treatments, but pain following injection was greater with propofol (59% vs. 9%). CONCLUSIONS: Patients receiving either eltanolone or propofol showed similar cardiovascular changes to induction of anesthesia, although there were greater increases in arterial pressure and HR in those patients receiving eltanolone.

Anesthesia↗

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.

Anesthesia↗

Use of condoms as blade covers during laryngoscopy, a method to reduce possible cross infection among patients.

OBJECTIVES: Laryngoscope blades are in close contact with mucous membranes and can possibly contaminated with virulent or readily transmissible organisms. As laryngoscopy is often required during endotracheal intubation, proper cleaning and sterilization of the laryngoscope blade is crucial to prevent cross-contamination among patients. METHODS: We tested the effectiveness of latex condom using as a laryngoscope blade cover during endotracheal intubation. Both control (no condom) and study group blades were rinsed with sterile saline after intubation. The rinse was sent for bacteria culture, and appearance of bacterial colonization was counted as positive. A water leak test (WLT) was performed on used condoms to verify their integrity. RESULTS: There were total 162 laryngoscopes studied with 83 (51.2%) scopes in the study group and 79 (48.8%) in the control group. Rate of positive bacterial culture were 13.3% and 88.6% in the study and control group, respectively. Although WLT (+) rate of 41% was found in the study group, a high negative culture rate (71.6%) was also noted among the WLT (+) group. CONCLUSIONS: Condom when using as a blade cover during laryngoscopy is a simple, inexpansive and effective way in reducing cross contamination among patients.

Bacteriological Techniques↗

A simple and reliable predictor for an adequate laryngeal view with rigid endoscopic laryngoscopy.

OBJECTIVES: It is sometimes impossible to obtain an adequate laryngeal view during rigid endoscopic laryngoscopy. This may be due to a high tongue base. Our study seeks to determine a correlation between tongue base level and the adequacy of laryngeal view obtained with a 70-degree rigid endoscope. STUDY DESIGN AND SETTING: Over a period of 4 months, patients from a voice clinic were gathered and categorized into class I to III according to Mallampati et al (1985). Rigid laryngo-videostroboscopy was conducted to assess the larynx and the adequacy of the view was recorded. RESULTS: 74 patients were recruited. The number of adequate views were: class I = 18/20 (90%); class II = 20/33 (60.6%); class III = 7/21 (33.3%). chi 2 analysis demonstrated significance trend in all 3 classes. CONCLUSION: The level of the tongue base correlated well with the adequacy of laryngeal view obtained from a 70-degree rigid endoscope. This can be used to predict the success of obtaining adequate views during rigid laryngoscopy.

Adolescent↗

Laryngoscopy.

The larynx normally functions in vocalization, deglutition, and respiration. There is no substitute for direct laryngoscopy in animals suspected of having laryngeal disease. Clinical signs that should alert the veterinarian include cough, choking while eating or drinking, exertional cyanosis and syncope, noisy breathing, inspiratory dyspnea, stridor, and significant change in sound production. Controlled anesthesia is mandatory for animals with suspected laryngeal disease because many of these patients have compromised respiratory function. Laryngoscopy is used to note abnormalities in the shape, color, and motility of the larynx with special attention to correlating the movement of the arytenoid cartilages and vocal folds with the respiratory cycle.

Animals↗

[Consequences and prevention methods of hemodynamic changes during laryngoscopy and intratracheal intubation].

In patients ranked ASA 1, laryngoscopy and intubation lead to an average increase in blood pressure of 40 to 50%, and a 20% increase in heart rate. These changes, which are greatest one minute after intubation, last for 5 to 10 min. They are due to sympathetic and adrenal stimulation, which may also result in some arrhythmias. About half the patient with coronary artery disease experience episodes of myocardial ischaemia during intubation when no specific prevention is undertaken. Among the different means available for this, narcotics seem to have a reliable and constant effect, but they may be responsible for postoperative respiratory depression. The protective effect of fentanyl starts at 2 micrograms.kg-1, and is at a maximum at 8 micrograms.kg-1. Lidocaine is the drug used most. Recent studies have questioned its efficacy. In clinical practice, it is particularly effective in preventing the pressor response to tracheal intubation, whatever its route of administration (intravenous or intratracheal), but not the increase in heart rate. Beta blockers with bradycardic, antihypertensive, antiarrhythmic and antiischaemic properties, have been advocated. As opposed to lidocaine, these agents are more effective in preventing the changes in heart rate than the pressor response. Because of their depressor effect on the myocardium, their place still remains to be defined, especially in the cardiac risk patient. Short-acting beta blockers should be preferred. Nitroglycerin is specifically indicated in coronary artery disease. Other agents, such as clonidine or calcium blockers, seem to be less effective or less convenient in preventing the haemodynamic alterations. In clinical practice, prevention will first rely on a sufficient dose of narcotics. In some cases, nitroglycerin or beta blockers may be used so as to decrease the doses of narcotics, without altering their efficacy; however, the risk of hypotension should be constantly borne in mind. If preventing measures have not been taken, short-acting antihypertensive agents (beta blockers, calcium blockers) should be used in patients who develop major hypertension during laryngoscopy and intubation.

Analgesics, Opioid↗

Evaluation of the cardiovascular responses to fiberoptic orotracheal intubation with television monitoring: comparison with conventional direct laryngoscopy.

STUDY OBJECTIVE: To evaluate and compare cardiovascular responses to a new method of orotracheal intubation incorporating TV monitoring, with conventional orotracheal intubation via rigid blade laryngoscopy. DESIGN: Prospective single-blind study. SETTING: Operating room of a medical college hospital. PATIENTS: 90 ASA physical status I and II surgical patients requiring general anesthesia and orotracheal intubation. INTERVENTIONS: Patients were randomly allocated to two groups, one for the new intubation method and the other for conventional intubation using a rigid laryngoscope. In the new method, an anesthesiologist inserted an endotracheal tube alone into the trachea via TV monitoring through the bronchoscope, which was inserted by an assistant through the mouth to the middle larynx. The patient's trachea was intubated without extreme stretching of laryngeal tissues or deep insertion of the tip of the bronchoscope. In the conventional method, orotracheal intubation was performed with rigid direct laryngoscopy. MEASUREMENTS: Noninvasive blood pressure (BP) and heart rate (HR) were measured before arrival at the operating room, and before and after orotracheal intubation. MAIN RESULTS: Although this method was expected to be a minimally invasive fiberoptic intubation technique, the patients showed significant increases in BP and HR. No significant differences between the two groups were observed in cardiovascular responses immediately after intubation: the systolic BP, 169.5 +/- 28.3 versus 167.0 +/- 23.1 mmHg, and HR, 100.2 +/- 18.2 versus 98.8 +/- 16.6 bpm. CONCLUSIONS: Insertion of an endotracheal tube may itself be the most invasive stimulus during intubation procedures.

Adult↗

Multidirectional observations of the larynx using transurethral rigid endoscopes during direct laryngoscopy.

Microscopic direct laryngoscopy (microlaryngoscopy) under general anaesthesia is the optimal method of observing the larynx. However, as microlaryngoscopy does not allow precise observations of the ventricle, inferior surface of the vocal fold and subglottis, multidirectional observations of the larynx using transurethral rigid endoscopes were performed during direct laryngoscopy. This endoscopic technique has been shown to be clinically useful in the diagnosis and treatment of laryngeal lesions. The equipment and methods are introduced herein, and a representative care is presented.

Anesthesia, Inhalation↗

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.

Adult↗

Cervical spine movements during laryngoscopy. Comparison of the Macintosh and McCoy laryngoscope blades.

We studied cervical spine movement in 10 patients scheduled for elective surgery under general anaesthesia. Each patient was fitted with a rigid cervical collar before undergoing direct laryngoscopy for orotracheal intubation. Laryngoscopy was performed using the McCoy laryngoscope in the activated position and the standard Macintosh blade. Displacement of the cervical spine at laryngeal exposure was measured using lateral cervical spine X-rays. Flexion and extension movements of the cervical spine during the use of the two laryngoscope blades were compared. For each blade, the greatest degree of extension occurred at the joint between the first and second cervical vertebrae. There was no significant difference in cervical spine movement when the two blades were compared.

Adult↗

Preoxygenation before laryngoscopy in children: how long is enough?

The ideal preoxygenation period prior to laryngoscopy in children is unclear. This study was performed to determine an appropriate duration of preoxygenation for infants and children prior to laryngoscopy using endtidal oxygen (FE'O2) criteria. Healthy paediatric patients for elective day surgery procedures were studied. An inflatable mask connected to an oxygen-primed paediatric anaesthesia semiclosed circuit was placed on the face while patients breathed spontaneously during 6.min-1 oxygen flow. An FE'O2 of 0.9 was considered the endpoint, and if not achieved in two min the protocol was ended. Fifty-eight children were studied. Six patients never achieved an FE'O2 of 0.9 and were not considered in the analysis. The times (in seconds with mean +/- SD and range) to achieve a minimum endtidal (FE'O2) of 0.9 for under six months were 36 +/- 11.4(20-50), 7-12 months were 35.5 +/- 13.3(20-60), 13-36 months were 42.6 +/- 18.7(20-90), 37-60 months were 50.8 +/- 18.5(30-90), > 60 months were 68.4 +/- 24.1(30-100). Logistic regression curves were determined for each age group describing the probability of achieving an FE'O2 of 0.9 against time of preoxygenation. All children with satisfactory mask fit were able to preoxygenate to an FE'O2 of 0.9 within 100 s.

Ambulatory Surgical Procedures↗

Bimanual laryngoscopy: a videographic study of external laryngeal manipulation by novice intubators.

STUDY OBJECTIVE: We perform a videographic analysis of external laryngeal manipulation (ELM) by novice intubators using a direct laryngoscopic imaging system and a validated means of assessing laryngeal view (percentage of glottic opening [POGO] score). METHODS: Nine first-year emergency medicine residents performed a total of 484 laryngoscopies during a 1-year study period, of which 271 were videotaped. Of this convenience sample, cases were included in the study if the initial laryngeal view had a POGO score of less than 50% and the quality of video imaging permitted POGO scoring before and after application of ELM. RESULTS: Seventy-two cases met the study criteria. Initial POGO scores equaled 0% in 30 cases, less than 20% in 20 cases, and 20% to 50% in 22 cases. ELM improved the POGO scores in all cases (95% confidence interval [CI] 96% to 100%) by an average of 57% (SD 23.7; 95% CI 40% to 75%). Among those with an initial POGO score equal to 0%, the mean improvement was 61% (SD 36.3; 95% CI 48% to 74%). For those with an initial POGO score of less than 20%, the mean improvement was 63% (SD 19.5; 95% CI 54% to 71%), and for those with an initial POGO score of 20% to 50%, the mean improvement was 47% (SD 16.0; 95% CI 40% to 55%). CONCLUSION: ELM is a simple and very effective technique for improving laryngeal view during laryngoscopy by novice intubators.

Clinical Competence↗

beta2 adrenoceptor (ADRB2) pharmacogenetics and cardiovascular phenotypes during laryngoscopy and tracheal intubation.

Pharmacogenetics is the study of genetic variations that cause a variable drug response characterized by alteration in drug metabolism or in pharmacodynamics. The polymorphisms in genes encoding receptors relevant to treatment cause variation in sensitivity to many drugs. beta2 Adrenoceptor genetic variation contributes to regulation of blood pressure and hemodynamic changes by mediating peripheral vasodilatation. Laryngoscopy and tracheal intubation associated with hemodynamic changes. Although there are four nonsynomic single-nucleotide polymorphisms (SNPs) of beta2 adrenoceptor gene, codon 16 (Arg16Gly) and codon 27 (Gln27Glu) SNPs are both common and functionally important. In this paper, the authors investigated the beta2 adrenoceptor Gly16 and Glu27 SNPs in response to drugs relevant to anesthesia and how these SNPs impacted upon the cardiovascular phenotypes. The authors measured arterial systolic and diastolic blood pressure, heart rate, and rate-pressure product before induction of anesthesia and 1 min following laryngoscopy and tracheal intubation. Genomic DNA was amplified and genotyped using allele-specific polymerase chain reaction (ASPCR) and restriction fragment length polymorphism (RFLP) assays, respectively. When the authors compared hemodynamic results according to genotypes, the patients with Gln homozygote allele at codon 27 exhibited significant increase of heart rate than patients with Glu allele after laryngoscope and tracheal intubation.

Adolescent↗

Anatomical factors in difficult direct laryngoscopy.

The anatomical factors in difficult direct laryngoscopy have been assessed. Thirteen patients in whom direct laryngoscopy proved difficult and thirteen control patients, all with teeth, had lateral, postero-anterior and submento-vertical radiographs taken. Several measurements were made and compared. The most important factor determining the ease of examination was the posterior depth of the mandible. An increase in this measurement was thought to hinder displacement of the soft tissues by the laryngoscope blade. Other factors of importance were: an increase in the anterior depth of the mandible; a reduction in the distance between the occiput and the spinous process of C1, and to a lesser extent the C1-C2 interspinous gap; and reduced mobility of the mandible associated with temporo-mandibular joint arthritis or trismus.

Adult↗

Prevention of intracranial hypertension during laryngoscopy and endotracheal intubation. Use of a second dose of thiopentone.

In nine patients, with preoperative ICP monitoring, anaesthesia was induced with thiopentone 5 mg kg-1 given over 1 min, followed by pancuronium 0.1 mg kg-1. After manual hyperventilation with nitrous oxide and oxygen for 3 min they were given thiopentone 2.5 mg kg-1 over 30 s (phase 1); 30 s later laryngoscopy was performed and topical analgesia administered to the larynx. Endotracheal intubation was performed 1 min after spraying the cords (phase 2). The measurements continued for a further 5 min during which the patients were mechanically ventilated (phase 3). ICP and intra-arterial pressure were recorded. Although there was a significant decrease (P less than 0.05) in MAP at the end of the second dose of thiopentone, there were no other significant changes in ICP, MAP or PaCO2 throughout the study. In two patients there were transient decreases in cerebral perfusion pressure to less than 60 mm Hg. Although MAP increased in five of the patients during laryngoscopy and intubation, there was no increase in ICP, showing that the MAP was still within the autoregulatory limits.

Adult↗

Disposition of cervical vertebrae, atlanto-axial joint, hyoid and mandible during x-ray laryngoscopy.

Ten healthy volunteers underwent direct laryngoscopy using topical anaesthesia and a curved Macintosh laryngoscope blade. A lateral x-ray was performed during laryngoscopy in a standard intubating position. In this position the lower neck was relatively straight and increasing curvature occurred from the mid cervical spine upwards. Extension at the atlanto-axial joint was probably near maximum; this has implications for conditions associated with laxity of this joint. The position of the mandible was influenced by the direction of pull on the laryngoscope handle. The hyoid was drawn forward and its body tilted downwards so as to lie halfway between the lower border of the mandible and the glottis. The relative length of epiglottis projecting above the hyoid was variable.

Adult↗