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At least 217 records · Page 12Linked to original sources

PubMed1990

Carbon dioxide monitoring during high frequency jet ventilation for direct laryngoscopy.

To improve ventilation monitoring during direct laryngoscopy, we have developed a high frequency jet ventilator which allows the aspiration of tracheal gas for carbon dioxide analysis (PtCO2) through the injector after stopping the ventilator. In 41 patients undergoing direct laryngoscopy, PaCO2 and PtCO2 were measured simultaneously during high frequency jet ventilation under general anaesthesia. PtCO2 and PaCO2 correlated significantly (r = 0.88), but PtCO2 underestimated PaCO2 by 0.84 (SD 0.72) kPa. The arterial to tracheal PCO2 difference was influenced by airway obstruction.

Anesthesia, General↗

PubMed1990

IV lignocaine fails to attenuate the cardiovascular response to laryngoscopy and tracheal intubation.

I.v. lignocaine has been used with varying success to attenuate the cardiovascular responses to laryngoscopy and tracheal intubation. We determined the optimal time of administration in 45 ASA I and II Chinese patients premedicated with morphine and hyoscine, and anaesthetized with thiopentone and suxamethonium. Patients were allocated randomly to a control group or three treatment groups to receive lignocaine 1.5 mg kg-1 i.v. 1, 2, or 3 min before laryngoscopy. Analysis of variance for measured and derived cardiovascular variables failed to show any significant difference between any of the groups.

Adult↗

PubMed1990

Measurement of end-expiratory pressure during transtracheal high frequency jet ventilation for laryngoscopy.

An anaesthetic technique using high frequency jet ventilation has been proposed for direct laryngoscopy, but this may expose the patients to the risk of barotrauma. In order to assess this risk, we have measured end-expiratory airway pressure (EEP) through the injector using two three-way solenoid valves mounted in series. At the end of insufflation the first valve was switched off and the apparatus deadspace connected to atmosphere through a large exit port during an adjustable time (decompression time). Then the second valve was switched off and the injection line connected to a transducer, allowing measurement of EEP through the injector. The accuracy of this measurement was tested against airway pressure measured directly in the trachea (Pt) in a lung model. Provided that the decompression time was long enough (70 ms) and the apparatus deadspace was small (6 ml), the difference between EEP and Pt was less than 1 cm H2O for frequencies up to 5 Hz. A clinical evaluation was performed in 64 patients under general anaesthesia before laryngoscopy. EEP correlated with end-expiratory pulmonary volume above apnoeic FRC inferred from abdominal and thoracic displacements. At jet frequencies up to 5 Hz, the correlations between these two variables were satisfactory (r greater than 0.88), suggesting that EEP is a good indicator of pulmonary overdistension.

Barotrauma↗

PubMed1990

Factor analysis in difficult tracheal intubation: laryngoscopy-induced airway obstruction.

We have studied eight patients with a history of difficult tracheal intubation, using x-ray laryngoscopy and local anaesthesia, a curved Macintosh blade and a standard intubating position. The view obtained was better than recorded previously during general anaesthesia in two patients, and in a third the x-ray showed that positioning the blade tip beneath the epiglottis would have improved vision, suggesting that reproducibility of the assessment may not be consistent. The "ease of intubation" and "complementary" angles may be helpful in the assessment of such patients. A "peardrop" effect is described whereby during laryngoscopy, the epiglottis became pressed against the posterior pharyngeal wall as a result of tongue compression. In the absence of muscle paralysis, removal of the blade caused immediate correction. However, during anaesthesia with neuromuscular block it is suggested that this not only occurs more readily but, may not correct when the blade is removed. Iatrogenic airway obstruction during moderately difficult tracheal intubation may be common and should be anticipated.

Airway Obstruction↗

PubMed1991

Unexpected, difficult laryngoscopy: a prospective survey in routine general surgery.

A prospective study of unexpected, difficult laryngoscopy was carried out. During a 7-month period, all general surgery patients in whom the trachea was intubated were assessed; only those with obvious neck pathology were excluded. Ease or difficulty of laryngoscopy was graded by a standard method. There were no grade 4 cases and no failed intubations in a total of 1387 cases. There were significant differences in the results recorded by different individuals; this did not correlate with seniority or with the type of surgery. Four factors have been identified which help to explain these discrepancies. These findings are analysed in relation to the training of junior staff, with particular reference to obstetric anaesthesia.

Anesthesia, Obstetrical↗

PubMed1992

Esmolol hydrochloride for management of the cardiovascular stress responses to laryngoscopy and tracheal intubation.

In a double-blind, randomized, controlled prospective study, 30 grade ASA I/II patients received a continuous i.v. infusion of normal saline or esmolol hydrochloride before induction of anaesthesia and tracheal intubation. Arterial pressure and heart rate were measured to assess the pressor response to laryngoscopy and intubation. The heart rate decreased in the esmolol group before induction of anaesthesia. The pressor response to laryngoscopy was significantly less marked in the esmolol group.

Anesthesia, General↗

PubMed1993

Mandibulohyoid distance in difficult laryngoscopy.

We studied radiographically 11 patients in whom direct laryngoscopy proved difficult and 100 control (general population) subjects. The vertical distance between the mandible and the hyoid bone (mandibulohyoid distance) was measured and the positions of the mandibular angle and hyoid bone determined in relation to the cervical vertebrae. We found that the mandibulohyoid distance was substantially longer in patients whose trachea was difficult to intubate; the mandibular angle tended to be positioned more rostrally in both men and women, and the hyoid bone tended to be positioned more caudally in women. This suggests that a relatively short mandibular ramus or a relatively caudal larynx may be important, unfavourable anatomic factors in difficult laryngoscopy.

Adult↗

PubMed1998

Laryngoscopy and fibreoptic intubation in acromegalic patients.

Acromegaly is recognized as a cause of difficulty in airway management and tracheal intubation. We evaluated prospectively the conditions for laryngoscopy and fibreoptic intubation in 15 acromegalic patients. Each patient served as his or her own control. Ventilation of the lungs with a face mask was successful in all patients. In five of 15 patients the vocal cords could not be seen using the Macintosh laryngoscope with a size 5 blade. Difficult laryngoscopy was associated significantly with the number of attempts required to see the vocal cords with the fibrescope (P < 0.01, Spearman rank correlation). The larynx could not be seen with both techniques in one patient, and the trachea was intubated blindly with the help of an introducer. Our results showed that fibreoptic intubation may prove difficult or fail in acromegalic patients. Difficulties in seeing the vocal cords with a fibrescope were present most often in patients who also had probable intubation difficulties with a rigid laryngoscope.

Acromegaly↗

PubMed2000

Comparison of different doses of remifentanil on the cardiovascular response to laryngoscopy and tracheal intubation.

We have compared three bolus and infusion regimens of remifentanil on the cardiovascular response to laryngoscopy and orotracheal intubation in three groups of 20 ASA I-II female patients, in a randomized, double-blind study. Patients in group 1 received glycopyrolate 200 micrograms i.v. followed by a bolus dose of remifentanil 1 microgram kg-1 over 30 s and an infusion of remifentanil at a rate of 0.5 microgram kg-1 min-1. The other patients received remifentanil 0.5 microgram kg-1 over 30 s and an infusion of 0.25 microgram kg-1 min-1 with (group 2) or without (group 3) pretreatment with glycopyrrolate 200 micrograms. All patients then received a sleep dose of propofol, rocuronium 0.6 mg kg-1 and 1% isoflurane with 67% nitrous oxide in oxygen. Laryngoscopy and tracheal intubation were performed 3 min later. Heart rate and arterial pressure were recorded at 1-min intervals from before induction of anaesthesia until 5 min after intubation. Baseline heart rate was similar in all groups, but decreased in group 3 (no glycopyrrolate) after induction and remained significantly lower after intubation compared with the other groups (P < 0.05). Heart rate and arterial pressure increased slightly after intubation in each group but there were no significant differences in mean arterial pressure between groups at any time. The incidence of bradycardia (one patient in group 2) and hypotension (two patients in groups 1 and 2 and three patients in group 3) was low.

Adult↗

PubMed1997

The efficacy of the "BURP" maneuver during a difficult laryngoscopy.

The displacement of the larynx in the three specific directions (a) posteriorly against the cervical vertebrae, (b) superiorly as possible, and (c) slightly laterally to the right have been reported and named the "BURP" maneuver. We evaluated the efficacy of the BURP maneuver in improving visualization of the larynx. Six hundred thirty patients without obvious malformation of the head and neck participated in this study. We divided the degree of visualization of the larynx using laryngoscopy into five grades and compared the visualization of the larynx using the BURP maneuver with that of laryngoscopy with and without simple laryngeal pressure ("Back"). The maneuver of Back and BURP significantly improved the laryngoscopic visualization from initial inspection. The BURP maneuver also significantly improved the visualization compared with the Back maneuver. We concluded that the BURP maneuver improved the visualization of the larynx more easily than simple back pressure on the larynx.

Female↗

PubMed2000

The use of esmolol, nicardipine, or their combination to blunt hemodynamic changes after laryngoscopy and tracheal intubation.

UNLABELLED: Laryngoscopy and tracheal intubation (LTI) often provoke an undesirable increase in blood pressure (BP) and/or heart rate (HR). We tested the premise that nicardipine (NIC) and esmolol (ESM) in combination (COMB) would oppose both. Adult surgical patients received pretreatment (randomized) with IV bolus NIC 30 microg/kg (n = 31), ESM 1.0 mg/kg (n = 34), or COMB (one-half dose each, n = 32). Peak BP and HR after LTI were compared with controls (CONT; n = 35) with no pretreatment. Anesthetic induction was standardized: IV thiopental (5-7 mg/kg), fentanyl (1-2 microg/kg), and succinylcholine (1.5 mg/kg). Systolic (S), diastolic (D), and mean (M) BP and HR awake before pretreatment (baseline) were similar in all test groups. No patient was treated for hypotension, bradycardia, or tachycardia after pretreatment or anesthetic induction. Peak HR after LTI was increased versus baseline in CONT and all test groups, but did not differ from CONT among the test groups. Peak SBP and DBP increased versus baseline in CONT, and with ESM and NIC, but not COMB. Peak SBP, DBP, and MBP were increased with ESM versus COMB, and peak DBP with ESM versus NIC. Compared with no pretreatment before the IV induction of general anesthesia, the peak increase in BP after LTI is best blunted by the combination of nicardipine and ESM, compared with either drug alone. No single drug or combination in the doses tested opposed increased HR. IMPLICATIONS: Compared with no pretreatment before the IV induction of general anesthesia, the peak increase in blood pressure after laryngoscopy and tracheal intubation is best blunted by the combination of nicardipine and esmolol, compared with either drug alone. No single drug or combination in the doses tested opposed increased heart rate.

Adrenergic beta-Antagonists↗

PubMed2000

Intravenous chloroprocaine attenuates hemodynamic changes associated with direct laryngoscopy and tracheal intubation.

We compared the effects of an IV administration of chloroprocaine and lidocaine on circulatory responses associated with endotracheal intubation. Thirty patients were randomly allocated to receive normal saline (placebo), lidocaine (1.5 mg/kg), or preservative-free chloroprocaine (4.5 mg/kg) 45 s before endotracheal intubation. Blood pressures and heart rate and rhythm were recorded before laryngoscopy and at 0.5, 1, 1.5, 2, 3, and 5 min after intubation. Blood samples were analyzed for catecholamine and chloroprocaine concentrations. Chloroprocaine reduced increases in blood pressure in response to intubation when compared with patients receiving normal saline and lidocaine. Systolic blood pressures at 0.5 and 1 min after intubation were significantly lower in the chloroprocaine group when compared with both the control and lidocaine groups (P < 0.05). Diastolic and mean blood pressures were significantly lower in the chloroprocaine group at all time points until 5 min after intubation (P < 0.05). Chloroprocaine and, to a lesser degree, lidocaine, produced marked attenuation of intubation-induced increases in plasma concentration of epinephrine and norepinephrine. Plasma concentrations of norepinephrine were significantly smaller in the chloroprocaine group at 0.5, 1, and 1.5 min, and plasma concentrations of epinephrine were significantly smaller at 0.5 after intubation when compared with control and lidocaine groups (P < 0.05). Measurable concentrations of chloroprocaine were recorded in plasma samples for 2 min after its administration. No adverse chloroprocaine effects (i.e., circulatory disturbances, venous irritation) were detected. The IV administration of chloroprocaine effectively blunted cardiovascular response produced by laryngoscopy and endotracheal intubation, and this effect was more pronounced when compared with IV lidocaine.

Adult↗

PubMed2001

The incidence of class "zero" airway and the impact of Mallampati score, age, sex, and body mass index on prediction of laryngoscopy grade.

IMPLICATIONS: In an earlier study we proposed the addition of a new airway class, zero (visualization of the epiglottis), to the four classes of the modified Mallampati classification. In this prospective study, 764 surgical patients were assessed with regard to their airway class (including class zero), laryngoscopy grade, and the effect of the airway class and other predictors on the laryngoscopy grade.

Adult↗

PubMed2002

Target-controlled versus manually-controlled infusion of propofol for direct laryngoscopy and bronchoscopy.

UNLABELLED: Few studies have compared the clinical profile of target-controlled infusions of propofol with that of manually-controlled infusions. Fifty-four ASA physical status I or II patients scheduled for an elective otorhinolaryngology endoscopy performed under general anesthesia with spontaneous ventilation were enrolled in this prospective randomized study to compare the clinical outcome of such administrations. Before induction, all patients received a single alfentanil bolus dose (10 microg/kg). Propofol administration was adapted to maintain absence of movement, hemodynamic stability, and efficient spontaneous ventilation. When compared with the Manually-Controlled Infusion group, in the Target-Controlled Infusion group there were fewer movements at insertion of the laryngoscope (14.8% vs. 44.4%), improved hemodynamic stability (largest variations of mean arterial blood pressure <10% of control values, versus 20%), fewer episodes of apnea, and less respiratory acidosis after endoscopy (pH = 7.37 +/- 0.05 and PaCO(2) = 50 +/- 7 mm Hg versus pH = 7.28 +/- 0.06 and PaCO(2) = 58 +/- 9 mm Hg); the recovery was also shorter (time to opening eyes or verbal response, 4.6 +/- 2.0 min and 6.8 +/- 2.5 min versus 10.8 +/- 7.3 min and 15.7 +/- 7.1 min). Propofol consumption was comparable in the two groups. Targeting the effect-site concentration improved the time course of the propofol drug effect during direct laryngoscopy performed during spontaneous ventilation when compared with manual infusion. IMPLICATIONS: This study compares the clinical profile of propofol anesthesia for direct laryngoscopy with spontaneous ventilation when the drug is administered either as a manually controlled infusion or by targeting the effect-site concentration through a target-controlled infusion (TCI) device. TCI improves the time course of propofol effects.

Adult↗

PubMed1994

Head extension and laryngeal view during laryngoscopy with cervical spine stabilization maneuvers.

BACKGROUND: Direct laryngoscopy frequently is modified in patients with known or suspected cervical spine injury. The goals of this study were to measure the degrees of head extension required to expose the arytenoid cartilages and glottis if neck flexion were not possible and to determine whether in-line stabilization maneuvers alter the amount of head extension. METHODS: The subjects were anesthesized patients with normal cervical spines and Mallampati class 1 oropharyngeal views. Head extension was measured relative to a line drawn perpendicular to the table. Stabilization consisted of either passive immobilization, with the head held flat against a rigid board, or axial traction. RESULTS: Without stabilization, arytenoid cartilage exposure and the best view of the glottis was achieved with a 10 +/- 5 degree (mean +/- SD) head extension and a 15 +/- 6 degree head extension, respectively (n = 31). Head immobilization reduced extension angles 4 +/- 5 degrees for arytenoid exposure and 5 +/- 6 degrees for best view compared with no stabilization. CONCLUSIONS: Head immobilization reduced head extension necessary for laryngoscopy. If head extension is construed to be potentially dangerous in patients with cervical spine injuries, head immobilization without traction might be the preferable stabilization technique.

Adolescent↗

PubMed2005

Cricoid pressure does not increase the rate of failed intubation by direct laryngoscopy in adults.

BACKGROUND: Cricoid pressure (CP) is applied during induction of anesthesia to prevent regurgitation of gastric content and pulmonary aspiration. However, it has been suggested that CP makes tracheal intubation more difficult. This double-blind randomized study evaluated the effect of CP on orotracheal intubation by direct laryngoscopy in adults. METHODS: Seven hundred adult patients undergoing general anesthesia for elective surgery were randomly assigned to have a standardized CP (n = 344) or a sham CP (n = 356) during laryngoscopy and intubation. After anesthesia induction and complete muscle relaxation, a 30-s period was allowed to complete intubation with a Macintosh No. 3 laryngoscope blade. The primary endpoint was the rate of failed intubation at 30 s. The secondary endpoints included the intubation time, the Cormack and Lehane grade of laryngoscopic view, and the Intubation Difficulty Scale score. RESULTS: Groups were similar for demographic data and risk factors for difficult intubation. The rates of failed intubation at 30 s were comparable for the two groups: 15 of 344 (4.4%) and 13 of 356 (3.7%) in the CP and sham CP groups, respectively (P = 0.70). The grades of laryngoscopic view and the Intubation Difficulty Scale score were also comparable. Median intubation time was slightly longer in the CP group than in the sham CP group (11.3 and 10.4 s, respectively, P = 0.001). CONCLUSIONS: CP applied by trained personnel does not increase the rate of failed intubation. Hence CP should not be avoided for fear of increasing the difficulty of intubation when its use is indicated.

Adult↗

PubMed2002

Laryngeal mask anesthesia with intraoperative laryngoscopy for identification of the recurrent laryngeal nerve during thyroidectomy.

OBJECTIVES/HYPOTHESIS: A critical step in thyroidectomy involves definitive identification of the recurrent laryngeal nerve (RLN). Using the laryngeal mask airway, identification of the RLN can be facilitated by stimulation of the nerve while monitoring vocal cord movement with a fiberoptic laryngoscope. We present this technique as an effective and safe means to identify the RLN during thyroid surgery, with significant advantages over existing techniques in appropriately selected patients. STUDY DESIGN: Retrospective case series. METHODS: We performed thyroidectomy on 8 patients (13 RLN identifications) in which laryngeal mask airway anesthesia with fiberoptic laryngoscopy was used to identify the RLN. Results are reviewed with regard to postoperative vocal cord function, as well as intraoperative and postoperative courses with laryngeal mask airway anesthesia. RESULTS: In all 13 cases in which the RLN was sought, it was definitively identified by witnessing brisk vocal cord movement on a video screen with stimulation of the RLN. No patient had postoperative vocal cord paresis or paralysis. Overall recovery from laryngeal mask airway anesthesia was uneventful and had advantages when compared with general anesthesia with endotracheal intubation. CONCLUSIONS: Laryngeal mask airway anesthesia with intraoperative fiberoptic laryngoscopy to identify the RLN is effective and safe in carefully selected patients. Advantages include decreased postoperative throat discomfort, absence of coughing during emergence from anesthesia, and elimination of the possibility of vocal cord mobility impairment secondary to RLN ischemia from the endotracheal tube balloon. In addition, this technique is applicable in operations besides thyroid surgery, in which definitive identification of the RLN is indicated.

Adult↗

PubMed2006

Continuous laryngoscopy exercise test: a method for visualizing laryngeal dysfunction during exercise.

OBJECTIVES/HYPOTHESIS: To assess the diagnostic feasibility and patient acceptance of a new developed diagnostic test for exercise induced upper airway flow limitation. STUDY DESIGN: Clinical case control study including evaluation of contemporary ergo-spirometry and laryngoscopy continuously performed during exercise. METHODS: Twelve nonsymptomatic controls and four young females with documented dyspnea and noisy breathing during exercise were studied. All subjects exercised to exhaustion on a treadmill while attached to a fully equipped ergo-spirometry unit and a fiberoptic laryngoscope linked to a video camera and a sound recorder. RESULTS: The test situation was well tolerated. Two control subjects had a minor inspiratory synchronous medial motion of the aryepiglottic folds without limitation of laryngeal airflow. In the four symptomatic subjects, exercise induced inspiratory synchronous medial motion of the dorsal part of the aryepiglottic folds as well as vocal cord adduction and inspiratory stridor was demonstrated. CONCLUSION: The continuous laryngoscopy exercise test was easy to perform, well tolerated, and can be implemented in future diagnostic work-up programs of laryngeal dysfunction.

Adolescent↗