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Laryngoscopy and pharyngeal pH are complementary in the diagnosis of gastroesophageal-laryngeal reflux.

Pharyngeal pH monitoring and laryngoscopy are routinely used to diagnose gastroesophageal-laryngeal reflux as a cause of respiratory symptoms. Although their use seems intuitive, their ultimate diagnostic value is yet to be defined. We studied 10 asymptomatic (control) subjects and 76 patients with respiratory symptoms. Both patients and control subjects were given a symptom questionnaire. Each underwent direct laryngoscopy using the reflux finding score (RFS) to grade laryngeal injury, esophageal manometry, and 24-hour esophagopharyngeal pH monitoring. The patients were then classified as RFS+, if the score was greater than 7, and pharyngeal reflux (PR)+, if they had more than one episode of PR detected during pH monitoring. The most common symptoms reported by patients were hoarseness (87%), cough (53%), and heartburn (50%). Control subjects had a significantly lower RFS (2.1 vs. 9.6, P < 0.01) and fewer episodes of PR (0.2 vs. 3.4, P < 0.01), than patients. None of the control subjects had more than one episode of PR during a 24-hour period. Fifty patients (66%) were RFS+ and 26 (34%) were RFS-. Thirty-two patients (42%) were PR+ and 44 (58%) were PR-. Fifteen patients had a normal RFS and no PR (group I = RFS-/PR-). Forty patients had discordance between the laryngoscopic findings and the pH monitoring (group II = RFS-/PR+ or RFS+/PR-). Twenty-one patients had both an abnormal RFS and PR (group III = RFS+/PR+). Patients in group III had significantly higher heartburn scores and distal esophageal acid exposure. Eighty-three percent of patients in group III but only 44% in group I improved their respiratory symptoms as a result of antireflux therapy. An abnormal PR or RFS differentiates patients with laryngeal symptoms from control subjects. Agreement between PR and RFS helps establish or refute the diagnosis of gastroesophageal reflux as a cause of laryngeal symptoms. Patients who are RFS+ and PR- may have laryngeal injury from another source, whereas patients who are RFS- and PR+ may not have acid entering the larynx, despite the presence of PR. Patients who are RFS+ and PR+ have more severe gastroesophageal reflux disease and their reflux causes laryngeal damage. Laryngoscopy and pharyngeal pH monitoring should be considered complementary studies in establishing the diagnosis of laryngeal injury induced by gastroesophageal reflux. ( J GASTROINTEST SURG 2002;6:189-194.)

Case-Control Studies↗

The effects of beta2 adrenoceptor gene polymorphisms on pressor response during laryngoscopy and tracheal intubation.

We investigated whether human beta2 adrenoceptor (beta2AR) gene polymorphisms are associated with the pressor response to laryngoscopy and tracheal intubation. Ninety-two patients undergoing elective surgery under general anaesthesia were enrolled into this study. Arterial systolic pressure, heart rate and rate pressure product were measured before induction of anaesthesia and 1 min following laryngoscopy and tracheal intubation. Genomic DNA was then used to identify the beta2AR-16 and beta2AR-27 genes using an allele-specific polymerase chain reaction method. Using multiple linear regression models, controlling for age, sex, weight, baseline blood pressure, heart rate and rate pressure product, we found that patients who possessed the glutamic acid homozygote of beta2AR-27 produced significantly greater changes in mean arterial pressure and rate pressure products than patients with the glutamine homozygote of beta2AR-27 (beta coefficient for mean blood pressure = 11.81, beta coefficient for pulse-pressure product = 8.76, both p-values = 0.023). These findings suggest that genetic variability in the human beta2AR gene polymorphisms may be associated with the pressor response to laryngoscopy and tracheal intubation.

Adult↗

Tracheal intubation and cervical spine excursion: direct laryngoscopy vs. intubating laryngeal mask.

Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.

Adult↗

Value of oropharyngeal Mallampati classification in predicting difficult laryngoscopy among obese patients.

The prediction of difficult intubation in obese patients was investigated by co-estimating the degree of visibility of oropharyngeal structures in conjunction with the respective body mass index. Data were collected prospectively in a series of 1833 consecutive adult patients. Body mass index (BMI) in kg m-2 was used as a measure of obesity (morbid: > 40, moderate: 30-40, no obesity: < 30). The oropharyngeal class findings were assessed using the original methodology as well as by a modification requiring the tongue to be pulled forward by the examiner. Difficult intubation was defined as inadequate exposure of the glottis by direct laryngoscopy. Both oropharyngeal class methodologies were of equal sensitivity, whereas the modified technique presented a significantly higher positive predictive value (50.0% vs. 37.2%, P < 0.01). Statistical analysis revealed an increased risk of difficult laryngoscopy among obese patients compared with subjects with normal body mass index (20.2% vs. 7.6%, P < 0.001). When obesity is estimated with respect to oropharyngeal class the positive predictive value is greatly improved (66.7% vs. 20.2%, P < 0.001). We conclude that obesity which is associated with a disproportionately large base of the tongue, is a predisposing factor for difficult laryngoscopy.

Adult↗

Comparison of the effects of topical lignocaine spray applied before or after induction of anaesthesia on the pressor response to direct laryngoscopy and intubation.

In an attempt to attenuate the cardiovascular pressor response to laryngoscopy and intubation, 30 patients presenting for routine ophthalmic surgery were studied and were randomly allocated into two groups: group A (n = 15) received direct laryngeal/tracheal lignocaine spray immediately before intubation; and group B (n = 15) received orolaryngeal lignocaine spray before the induction of anaesthesia. In both groups, general anaesthesia was induced with thiopentone 3-5 mg kg-1, followed by atracurium 0.6 mg kg-1 to facilitate tracheal intubation. Laryngoscopy and endotracheal intubation caused a significant increase in heart rate, by 28% in group A and 23% in group B (P < 0.05 in both), and in diastolic blood pressure, by 28% in group A and 24% in group B (P < 0.05 in both). In group A, the systolic blood pressure also increased significantly (by 18%) after intubation, but there was no significant change in group B. In addition, the plasma lignocaine concentrations remained well below the toxic range in both groups. It was concluded that topical lignocaine administration as an orolaryngeal spray before the induction of anaesthesia is effective in reducing but not abolishing the pressor response to laryngoscopy and endotracheal intubation.

Administration, Topical↗

Voice changes and thyroid surgery: is pre-operative indirect laryngoscopy necessary?

BACKGROUND: Indirect laryngoscopy (IDL) is often performed prior to thyroid surgery to detect pre-existing vocal cord pathology. METHODS: A retrospective chart review of 201 patients undergoing thyroid surgery at the Prince of Wales Hospital was undertaken in order to study the patterns of pre-operative and postoperative voice changes and IDL findings. RESULTS: A total of 9% of patients had pre-operative voice symptoms, and 22% of this group had abnormalities detected on pre-operative IDL. Of 160 documented IDL, 4% revealed vocal cord pathology in asymptomatic patients, including an asymptomatic recurrent laryngeal nerve palsy. CONCLUSIONS: Indirect laryngoscopy remains a useful but flawed pre-operative screening tool for patients with voice symptoms, but the literature suggests that more advanced phoniatric tests will provide superior diagnostic sensitivity. The role of routine pre-operative laryngoscopy for asymptomatic patients is of debatable value.

Hoarseness↗

Stress response to tracheal intubation in patients undergoing coronary artery surgery: direct laryngoscopy versus an intubating laryngeal mask airway.

OBJECTIVE: Stress response caused by endotracheal intubation may be harmful for the coronary or cerebral circulation of high-risk patients. This study evaluated the hypothesis that tracheal intubation via an intubating laryngeal mask airway is associated with less cardiovascular and endocrine stress response than the conventional technique using direct laryngoscopy. DESIGN: Randomized, patient-blinded trial. SETTING: University department (single center). PARTICIPANTS: Eighty-six patients undergoing elective coronary artery surgery. INTERVENTION: Tracheal intubation was performed via an intubating laryngeal mask or by conventional direct laryngoscopy after standardized induction of anesthesia. MEASUREMENTS AND MAIN RESULTS: Electrocardiogram with automatic ST-segment analysis and invasive measured blood pressure were recorded continuously and blood samples to analyze norepinephrine plasma levels were taken at 4 times. Catecholamine concentrations and the pressure-rate product were analyzed by using an analysis of variance for repeated measures. In both groups, the pressure-rate product (p = 0.003) and norepinephrine concentrations (p < 0.0001) significantly decreased after induction of anesthesia. However, the fall was more marked in the patients intubated via the laryngeal mask (p = 0.031) than in patients receiving direct laryngoscopy. There were neither signs of cardiac ischemia nor major adverse events during induction of anesthesia. CONCLUSIONS: Reduction of cardiovascular and endocrine stress response associated with endotracheal intubation is more pronounced when performed via the intubating laryngeal mask. Thus, this technique can be helpful in high-risk cardiac patients.

Aged↗

Colour texture analysis for quantitative laryngoscopy.

OBJECTIVE: Whilst considerable progress has been made in enhancing the quality of indirect laryngoscopy and image processing, the evaluation of clinical findings is still based on the clinician's judgement. The aim of this paper was to examine the feasibility of an objective computer-based method for evaluating laryngeal disease. MATERIAL AND METHODS: Digitally recorded images obtained by 90 degree- and 70 degree-angled indirect rod laryngoscopy using standardized white balance values were made of 16 patients and 19 healthy subjects. The digital images were evaluated manually by the clinician based on a standardized questionnaire, and suspect lesions were marked and classified on the image. Following colour separation, normal vocal cord areas as well as suspect lesions were analyzed automatically using co-occurrence matrices, which compare colour differences between neighbouring pixels over a predefined distance. RESULTS: Whilst colour histograms did not provide sufficient information for distinguishing between healthy and diseased tissues, consideration of the blue content of neighbouring pixels enabled a correct classification in 81.4% of cases. If all colour channels (red, green and blue) were regarded simultaneously, the best classification correctness obtained was 77.1%. CONCLUSIONS: Although only a very basic classification differentiating between healthy and diseased tissue was attempted, the results showed progress compared to grey-scale histograms, which have been evaluated before. The results document a first step towards an objective, machine-based classification of laryngeal images, which could provide the basis for further development of an expert system for use in indirect laryngoscopy.

Color↗

A biomechanical model of the upper airways for simulating laryngoscopy.

This paper describes a three-dimensional finite element model of the human upper airways during rigid laryngoscopy. In this procedure, an anaesthetist uses a rigid blade to displace and compress the tongue of the patient, and then inserts a tube into the larynx to allow controlled ventilation of the lungs during an operation. A realistic model of the main biomechanical aspects involved would help anaesthetists in training and in predicting difficult cases in advance. For this purpose, the finite element method was used to model structures such as the tongue, ligaments, larynx, vocal cords, bony landmarks, laryngoscope blade, and their inter-relationships, based on data extracted from X-ray, MRI, and photographic records. The model has been used to investigate how the tongue tissue behaves in response to the insertion of the laryngoscope blade, when it is subjected to a variety of loading conditions. In particular, the mechanical behaviour of the soft tissue of the tongue was simulated, from simple linear elastic material to complex non-linear viscoelastic material. The results show that, within a specific set of tongue material parameters, the simulated outcome can be successfully related to the view of the vocal cords achieved during real laryngoscopies on normal subjects, and on artificially induced difficult laryngoscopy, created by extending the upper incisors teeth experimentally.

Biomechanical Phenomena↗

Studies of anaesthesia in relation to hypertension. VII: Adrenergic responses to laryngoscopy.

Arterial pressure and plasma catecholamine concentrations were measured in 16 normotensive and 10 hypertensive patients undergoing elective vascular surgery. Following induction of anaesthesia, both arterial pressure and plasma noradrenaline concentrations decreased in both groups. Following laryngoscopy, there was a moderate increase in arterial pressure in both normotensive and hypertensive patients. In normotensive patients, laryngoscopy was associated with a moderate increase in plasma noradrenaline concentration. There was no change in adrenaline concentration. By contrast, there was a marked increase in noradrenaline concentration, a moderate increase in adrenaline concentration and an arterial pressure response in the group of hypertensive patients. These data are consistent with transient sympathetic overactivity in hypertensive patients following noxious stimuli such as laryngoscopy.

Adrenergic beta-Antagonists↗

Alfentanil obtunds the cardiovascular and sympathoadrenal responses to suxamethonium-facilitated laryngoscopy and intubation.

Alfentanil 75 micrograms kg-1 or saline (control group) was given 1 min before induction of anaesthesia in 20 healthy patients premedicated with diazepam 0.14 mg kg-1 and pethidine 1 mg kg-1. Anaesthesia was induced with a sleep dose of thiopentone preceded by glycopyrrolate. Suxamethonium 1 mg kg-1 was used to facilitate laryngoscopy (which lasted 10 s) and tracheal intubation. Arterial pressure, heart rate and noradrenaline concentration in mixed venous plasma increased significantly after suxamethonium, and increased further after laryngoscopy and intubation in the control group (n = 10). The QT interval of the ECG was prolonged after the administration of suxamethonium, and was prolonged further after laryngoscopy and intubation. All these changes were attenuated in patients pretreated with alfentanil (n = 10), but four patients had chest wall rigidity. Changes in the QT interval correlated directly with the changes in plasma noradrenaline concentration (r = 0.67). Plasma adrenaline concentrations decreased during induction of anaesthesia in both groups.

Adult↗

Does the choice of antihypertensive therapy influence haemodynamic responses to induction, laryngoscopy and intubation?

We have measured haemodynamic responses to induction of anaesthesia, laryngoscopy and intubation in 103 mild-moderate hypertensive patients (83 patients (diastolic pressures < or = 110 mm Hg) currently receiving one of four monotherapies (ACE inhibitors, group A; beta adrenoceptor blocking drugs, group B; calcium channel antagonists, group C; diuretics, group D) and 24 were untreated hypertensive patients). Anaesthesia was induced with fentanyl 1.5-2.0 micrograms kg-1 and thiopentone 3-5 mg kg-1. Tracheal intubation was facilitated by vecuronium 0.1 mg kg-1 and anaesthesia maintained with enflurane and nitrous oxide in oxygen. Systolic and diastolic pressures (SAP, DAP) were measured at 1-min intervals by a non-invasive oscillometric method and cardiac output (CO) and stroke volume (SV) by thoracic bioimpedance. Induction of anaesthesia was associated with a decrease in SAP, DAP and CO in groups A-D (P < 0.05). Heart rate (HR) decreased in groups A and D (P < 0.01) and systemic vascular resistance (SVR) decreased in groups A and B (P < 0.05). SAP and HR increased in all groups after laryngoscopy and intubation (P < 0.01) as did SVR in groups A, B and D (P < 0.02). CO was unaltered. Similar changes occurred in the untreated hypertensive patients, although nine of 24 patients exhibited HR > or = 100 beat min-1 after laryngoscopy and intubation. Comparison of the changes in SAP, DAP, CO and SVR with time showed no differences in the five treatment groups; changes in HR were significantly less in group B compared with the other groups (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

Difficult laryngoscopy in cleft lip and palate surgery.

We studied prospectively 800 paediatric patients undergoing repair of cleft lip and palate to determine the predictors of difficult laryngoscopy. The incidence of difficult laryngoscopy (Cormack and Lehane grade III and IV) was 2.95% in patients with unilateral cleft lip, 45.76% in bilateral cleft lip and 34.61% in patients with retrognathia. Tracheal intubation was successful in 99% of patients in whom laryngoscopy was difficult. There was a significant association between age and laryngoscopic view (P < 0.01).

Age Factors↗

Gabapentin attenuates the pressor response to direct laryngoscopy and tracheal intubation.

BACKGROUND: Laryngoscopy and tracheal intubation increase blood pressure and heart rate (HR). The aim of the present study was to investigate the effect of gabapentin when given before operation on the haemodynamic responses to laryngoscopy and intubation. METHODS: Forty-six patients undergoing abdominal hysterectomy for benign disease were randomly allocated to receive gabapentin 1,600 mg or placebo capsules at 6 hourly intervals starting the day (noon) before surgery. Anaesthesia was induced with propofol and cis-atracurium. Systolic, diastolic arterial blood pressures (SAP, DAP) and heart rate (HR) were recorded before and after the anaesthetic and 0, 1, 3, 5 and 10 min after tracheal intubation. RESULTS: SAP was significantly lower in the gabapentin vs the control group 0, 1, 3, 5 and 10 min after intubation [128 (27) vs 165 (41), P=0.001, 121 (14) vs 148 (29), P=0.0001, 115 (13) vs 134 (24), P=0.002, 111 (12) vs 126 (19), P=0.004 and 108 (12) vs 124 (17), P=0.001 respectively]. DAP also was lower in the gabapentin group 0, 1, 3, and 10 min after intubation [81 (18) vs 104 (19), P=0.0001, 77 (9) vs 91 (16), P=0.001, 71 (10) vs 84 (13), P=0.001 and 67 (10) vs 79 (12), P=0.004]. HR did not differ between the two groups at any time [82 (11) vs 83 (15), 79 (10) vs 80 (12), 86 (17) vs 92 (10), 82 (11) vs 88 (10), 81 (12) vs 81 (11), 77 (13) vs 79 (13), and 75 (15) vs 78 (12)]. CONCLUSION: Gabapentin, under the present study design attenuates the pressor response but not the tachycardia associated with laryngoscopy and tracheal intubation.

Adult↗

Cervical spine motion with direct laryngoscopy and orotracheal intubation. An in vivo cinefluoroscopic study of subjects without cervical abnormality.

BACKGROUND: Cervical spine kinetics during airway manipulation are poorly understood. This study was undertaken to quantify the extent and distribution of segmental cervical motion produced by direct laryngoscopy and orotracheal intubation in human subjects without cervical abnormality. METHODS: Ten patients without clinical or radiographic evidence of cervical spine abnormality underwent laryngoscopy using a #3 Macintosh blade while under general anesthesia and neuromuscular blockade. Cervical motion was recorded with continuous lateral fluoroscopy. The intubation sequence was divided into distinct stages and the corresponding fluoroscopic images were digitized. Segmental motion, occiput through C5, was calculated for each stage using the digitized data. RESULTS: During exposure and laryngoscope blade insertion, minimal displacement of the skull base and rostral cervical vertebral bodies was observed. Visualization of the larynx created superior rotation of the occiput and C1 in the sagittal plane, and mild inferior rotation of C3-C5. C2 maintained nearneutral posture. This pattern of displacement resulted in extension at each motion segment, with the most significant motion produced at the occipitoatlantal and atlantoaxial joints (mean = 6.8 degrees and 4.7 degrees, respectively). Intubation created slight additional superior rotation at the occiput and C1, without substantial alteration in the posture of C2-C5. After laryngoscope removal, position trended toward baseline at all levels, although exact neutral posture was not regained. CONCLUSIONS: This investigation quantifies the behavior of the normal cervical spine during direct laryngoscopy with a Macintosh blade. With this maneuver, the vast majority of cervical motion is produced at the occipitoatlantal and atlantoaxial joints. The subaxial cervical segments (C2-C5) are displaced only minimally. This study establishes a highly reliable and reproducible method for analyzing cervical motion in real time.

Adult↗

Pharmacodynamic interaction between propofol and remifentanil regarding hypnosis, tolerance of laryngoscopy, bispectral index, and electroencephalographic approximate entropy.

BACKGROUND: The purpose of this investigation was to describe the pharmacodynamic interaction between propofol and remifentanil for probability of no response to shaking and shouting, probability of no response to laryngoscopy, Bispectral Index (BIS), and electroencephalographic approximate entropy (AE). METHODS: Twenty healthy volunteers received either propofol or remifentanil alone and then concurrently with a fixed concentration of remifentanil or propofol, respectively, via a target-controlled infusion. Responses to shaking and shouting and to laryngoscopy were assessed multiple times after allowing for plasma effect site equilibration. The raw electroencephalogram and BIS were recorded throughout the study, and AE was calculated off-line. Response surfaces were fit to the clinical response data using logistic regression or hierarchical response models. Response surfaces were also estimated for BIS and AE. Surfaces were visualized using three-dimensional rotations. Model parameters were estimated with NONMEM. RESULTS: Remifentanil alone had no appreciable effect on response to shaking and shouting or response to laryngoscopy. Propofol could ablate both responses. Modest remifentanil concentrations dramatically reduced the concentrations of propofol required to ablate both responses. The hierarchical response surface described the data better than empirical logistic regression. BIS and AE are more sensitive to propofol than to remifentanil. CONCLUSIONS: Remifentanil alone is ineffective at ablating response to stimuli but demonstrates potent synergy with propofol. BIS and AE values corresponding to 95% probability of ablating response are influenced by the combination of propofol and remifentanil to achieve this endpoint, with higher propofol concentrations producing lower values for BIS and AE.

Adult↗

Safety of direct laryngoscopy as an outpatient procedure.

The safety of outpatient direct laryngoscopy has recently been challenged in the literature. We reviewed the first 589 direct laryngoscopies performed at a new outpatient surgery center. There were nine unplanned admissions to the hospital, including five airway emergencies that developed within the first 30 min after extubation. Three patients required reintubation before leaving the operating room. On postoperative telephone follow-up, 9% complained of mild to moderate sore throat. There were no major complications after discharge. We conclude that the risk of airway emergencies after direct laryngoscopy is less than 1% in carefully selected patients. The procedure can be safely performed as an outpatient procedure as long as transportation to a hospital is readily available for the few patients in whom complications arise.

Adult↗

Correlation of findings on direct laryngoscopy and bronchoscopy with presence of extraesophageal reflux disease.

OBJECTIVE: To determine the correlation between findings at direct laryngoscopy and bronchoscopy and presence of extraesophageal reflux disease (EERD). STUDY DESIGN: Retrospective chart review METHODS: Operative notes of 155 children undergoing direct laryngoscopy and bronchoscopy between 1996 and 1999 for airway symptoms for whom there was a suspicion of EERD were examined. Gastroesophageal reflux disease (GERD) was considered present if at least one test was positive (including upper GI series, pH probe, gastric scintiscan, or esophageal biopsy). RESULTS: A total of 130 (84%) patients had GERD diagnosed. Ninety percent had at least one laryngotracheal abnormality: 83% had an abnormal larynx and 66% had an abnormal trachea. Laryngeal abnormalities in GERD included postglottic edema, 69%; arytenoid edema, 30%; large lingual tonsil, 16%; vocal fold edema, 12%; vocal fold nodule, 12%; ventricular obliteration, 5%; and hypopharyngeal cobblestoning, 3%. Tracheobronchial abnormalities in GERD included tracheal cobblestoning, 33%; blunting of carina, 12.5%; subglottic stenosis, 11%; increased secretions, 11%; and generalized edema or erythema, 5%. The best sensitivity or specificity was obtained by combining postglottic edema, arytenoid edema, and vocal fold edema, resulting in a sensitivity of 75% and a specificity of 67%. Positive predictive value was 100% for the combination of postglottic edema and any vocal fold or ventricular abnormality. CONCLUSION: Laryngoscopy and bronchoscopy can reveal findings with a high positive predictive value for the presence of GERD. Endoscopy of the upper airway in children with clinical signs and symptoms of EERD is a promising tool for diagnosis.

Bronchi↗