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Inspiratory activation of the vocal cord adductor, part I: human study in patients with restricted abduction of the vocal cords.

OBJECTIVES/HYPOTHESIS: In patients with restricted abduction of the vocal cords, it has generally been accepted that glottis narrowing with laryngeal stridor during inspiration is attributed to static and passive obstruction of the glottis. However, active glottis narrowing can also be contributory. We tested the hypothesis that the vocal cord adductor is activated during inspiration in patients with restricted abduction of the vocal cords. STUDY DESIGN: Electromyographic evaluation of vocal cord adductor activity in patients with restricted abduction of the vocal cords. METHODS: Five patients with restricted abduction of the vocal cords who had stridor with mild to severe dyspnea during wakefulness were anesthetized with propofol. We recorded the adductor muscle electromyogram during breathing through a laryngeal mask airway while observing the vocal cord movement endoscopically. In three patients who had undergone tracheostomy, we also recorded adductor firing patterns not only while closing but also while opening the tracheostoma. RESULTS: The adductor was activated during inspiration, and the glottis was narrowed in accordance with inspiratory stridor. This adductor inspiratory activity was abolished by opening the tracheostoma in the tracheostomized patients. CONCLUSION: Not only static or passive glottis narrowing but also active narrowing may contribute to inspiratory flow limitation in patients with restricted abduction of the vocal cords. This active glottis narrowing is probably induced by an airway reflex.

Adolescent↗

Subacute airway obstruction from a tracheal mucosal flap.

We report the case of a 15-year-old girl with a near fatal obstructive tracheal lesion following tracheal intubation. The patient developed stridor and acute respiratory distress 29 h following tracheal extubation, after 35 h intubation in the intensive care unit. The failure of conventional management of stridor, including re-intubation, to provide a satisfactory airway prompted an urgent bronchoscopy, which revealed a tracheal mucosal flap causing 80% obstruction of the subglottic trachea. The fibreoptic bronchoscope allowed careful placement of a tracheal tube distal to the obstruction. The patient eventually made a full recovery. The low incidence of similar lesions and the lack of distinguishing clinical features from other causes of post-extubation stridor make diagnosis and appropriate management of this life-threatening condition difficult. We discuss how early consideration of the diagnosis and optimal initial management reduce the risk of an adverse outcome.

Adolescent↗

Evaluation of a new recommendation for improved cuffed tracheal tube size selection in infants and small children.

BACKGROUND: The purpose of this study was to evaluate a new recommendation for tracheal tube size selection using second-generation Microcuff paediatric endotracheal tubes (PETs) with optimized outer diameter (OD) of the distal tube. METHODS: With Ethics Committee approval, patients aged from birth to 5 years, requiring general anaesthesia with orotracheal intubation, were included. Tracheal tube sizes were selected as follows: internal diameter (ID) 3.0 mm, birth (if > or =3 kg) to <6 months; ID 3.5 mm, 6 to <18 months; ID 4.0 mm, 18 months to <3 years; ID 4.5 mm, 3 to <5 years. Tracheal tubes with the cuff not inflated were classified as too large if no air leak was obtained at an airway pressure of < or =20 cmH2O. Post-intubation stridor requiring therapy was noted. RESULTS: Three hundred and fifty children were studied. Nine tracheal tubes (2.6%) were too large and had to be exchanged: in patients requiring tracheal tubes of ID 3.0 mm and 3.5 mm, three and four tracheal tubes, respectively, and, in patients requiring tracheal tubes of ID 4.0 mm and 4.5 mm, one tracheal tube in each group. In three patients (0.9%), post-intubation stridor occurred which required therapy. CONCLUSION: The new recommendation presented for the use of second-generation Microcuff PETs with improved OD to ID ratio allows the selection of cuffed tracheal tubes with larger IDs than previously recommended for small children without increased need for tracheal tube exchange or increased incidence of post-intubation stridor in these age groups.

Age Factors↗

Lingual cyst in infancy: importance of palpation for diagnosis.

Two infants, 5 and 12 weeks of age, with lingual cysts were presented. Histological findings were compatible with a salivary retention cyst in one and a thyroglossal duct cyst in the other. Both infants were admitted to our hospital because of severe stridor that had developed from one to two weeks of age. Their lingual cysts were easily recognizable by simple palpation and were confirmed by non-invasive imaging techniques, such as ultrasound sonography, computed tomography and magnetic resonance imaging. Lingual cyst in infancy may be large enough to cause stridor and dyspnea, and occasionally result in sudden infant death, although once diagnosis is made a radical operation can be easily performed. Therefore, it is important that palpation in the oral cavity should be performed with all infants with persistent stridor as a part of a physical examination.

Cysts↗

Pathogenesis of laryngeal narrowing in patients with multiple system atrophy.

1. We do not fully understand the pathogenesis of nocturnal laryngeal stridor in patients with multiple system atrophy (MSA). Recent studies suggest that inspiratory thyroarytenoid (TA) muscle activation has a role in the development of the stridor. 2. The breathing pattern and firing timing of TA muscle activation were determined in ten MSA patients, anaesthetized with propofol and breathing through the laryngeal mask airway, while the behaviour of the laryngeal aperture was being observed endoscopically. 3. Two distinct breathing patterns, i.e. no inspiratory flow limitation (no-IFL) and IFL, were identified during the measurements. During IFL, significant laryngeal narrowing was observed leading to an increase in laryngeal resistance and end-tidal carbon dioxide concentration. Development of IFL was significantly associated with the presence of phasic inspiratory activation of TA muscle. Application of continuous positive airway pressure suppressed the TA muscle activation. 4. The results indicate that contraction of laryngeal adductors during inspiration narrows the larynx leading to development of inspiratory flow limitation accompanied by stridor in patients with MSA under general anaesthesia.

Aged↗

Tumor conference No. 9. Massive hemangioma with pharyngeal involvement.

When first seen in May, 1974, this 7-week-old child presented a rapidly enlarging hemangioma involving her face, scalp, oral mucous membranes and pharynx. Because of the development of stridor and complete closure of the eyelids of one eye by the hemangioma, the child was placed on systemic corticosteroid therapy. This was continued for a three-month period at which point it was discontinued. There was unquestionalbe shrinkage of the tumor during therapy. The stridor disappeared and the eyelids opened within a few days. Within six days of discontinuation of the corticosteroids, there was sudden enlargement of the lesion and reappearance of stridor which again subsided after a six-week course of systemic corticosteroids. Currently, the child is still under observation. It is anticipated that further spontaneous resolution will take place but that she will require plastic surgery for some of the residual deformities. The questions of ocular involvement, cardiac enlargement, occlusion of the pharyngeal airway, and arteriovenous anastamoses were raised in this child. Newer treatments including embolization treatments and cryotherapy were considered for this child but were not pursued since the growth of the hemangioma came to a virtual standstill and the child is otherwise thriving.

Adrenal Cortex Hormones↗

Early diagnosis and stage classification of vocal cord abductor paralysis in patients with multiple system atrophy.

OBJECTIVES: Vocal cord abductor paralysis (VCAP) is a life threatening complication which may cause nocturnal sudden death in patients with multiple system atrophy. However, the early diagnosis of VCAP is often difficult to make on routine laryngoscopy performed during wakefulness, as stridor, which is the sole symptom of VCAP in the early stage, develops only during sleep. The aim was to investigate laryngeal dysfunction in patients with multiple system atrophy while awake and asleep. METHODS: Seven patients with multiple system atrophy with nocturnal stridor and five control patients were studied. Vocal cord movement was analysed by laryngoscopy while the patients were awake and also during sleep induced by intravenous diazepam. RESULTS: When awake, for the seven patients with multiple system atrophy normal movement of the vocal cords occurred in three, mild abduction restriction in three, and paradoxical movement in one. When asleep, however, all showed obvious paradoxical movement with high pitched inspiratory stridor. In controls, there were no differences in the vocal cord movement between wakefulness and sleep. From these findings, VCAP could be divided into four stages: stage 0 (normal) with normal vocal cord movement during both wakefulness and sleep, stage 1 (mild VCAP) with normal movement during wakefulness and paradoxical movement during sleep, stage 2 (moderately severe VCAP) with abduction restriction during wakefulness and paradoxical movement during sleep, and stage 3 (severe VCAP) with an almost midline position for the vocal cords during both wakefulness and sleep. CONCLUSIONS: Laryngoscopy during sleep can disclose subclinical VCAP, making an early diagnosis of VCAP in patients with multiple system atrophy. Stage 2 of VCAP seems to be a suitable stage for tracheostomy in patients with multiple system atrophy.

Aged↗

Myasthenic inspiratory vocal cord dysfunction: efficacy of nasal continuous positive airway pressure treatment.

Myasthenic vocal cord dysfunction (VCD), presenting with severe inspiratory stridor, was successfully treated with nasal continuous positive airway pressure (nCPAP), thus giving the medical staff time to make the diagnosis and avoiding intubation or tracheostomy. An important sign leading to diagnosis was the very high MEF(50)/MIF(50) ratio calculated from the flow-volume loop. nCPAP treatment induced prompt remission of stridor and a sharp reduction in the MEF(50)/MIF(50) ratio from 9.90 to 1.36. A review of the literature has shown that VCD with inspiratory stridor is an unusual onset symptom of myasthenia gravis and that nCPAP treatment may avoid emergency oral/tracheal intubation and tracheostomy. After diagnosis, the patient underwent thymectomy, and today, 3 years later, he is well without any further therapy.

Adult↗

Comparison of airway resistance and total respiratory system resistance in infants.

Airway resistance (Raw) can be measured throughout the respiratory cycle by whole body plethysmography. Total resistance of the respiratory system (Rrs) can be measured from the relaxed expiration that follows end inspiratory occlusion. The purpose of this study was to compare the two methods in normal infants and in infants with airway obstruction of different types and severity. Fifteen infants with essentially normal lungs aged 24.6 +/- 18.0 (SD) wk, nine infants with congenital stridor aged 36.0 +/- 17.3 wk, and eleven wheezy infants aged 20.1 +/- 11.3 wk had simultaneous measurements of Raw and Rrs. Rrs was similar to Raw both during inspiration and expiration in the normal infants, to all expiratory Raw in those with congenital stridor, and to all inspiratory and early expiratory Raw in the wheezy infants. Raw was markedly and significantly higher than Rrs during mid and late inspiration in infants with congenital stridor and during late expiration in the wheezy infants. We conclude that Rrs is a good estimate of Raw in normal infants and of early expiratory Raw in all infants. In infants with airway obstruction, Rrs does not reveal the dynamic changes in Raw during tidal breathing, nor can it differentiate between infants with upper and lower airway obstruction.

Airway Resistance↗

Acoustic analysis of upper airway obstruction in the excised human larynx.

Upper airway obstruction is an emergency that requires quick and decisive intervention. Stridor is the sound created by airflow through a partially obstructed airway, and has been described to vary with the site and degree of obstruction. This study sought to determine the sound characteristics of stridor in the excised human larynx. Five fresh cadaver human larynges were harvested and subjected to obstructions at supraglottic, glottic, and subglottic subsites. Subglottic pressure, airflow, and audio signal were recorded. Data were analyzed on the basis of laryngeal obstruction subsite and the degree of laryngeal resistance. Visual inspection demonstrated certain trends in peak spectral energy depending on the site and, more significantly, the amount of obstruction. Statistical analysis of spectral waveforms showed better correlation with the amount of obstruction than with the site of obstruction. In summary, the frequency distribution of stridor produced in an excised human larynx was influenced by the amount of laryngeal resistance, but not by the site of airway obstruction.

Acoustics↗

Laser aryepiglottoplasty for the treatment of neurasthenic laryngomalacia in cerebral palsy.

Patients with cerebral palsy usually suffer from lack of coordination in the neuromuscular mechanism in their upper airway and digestive tract. Difficulty in swallowing and aspiration are common problems in these patients, and stridorous breathing sometimes develops as a secondary symptom. Laryngoscopic examination revealed that redundant tissue in the aryepiglottic fold area was the cause of stridor and upper airway obstruction in four patients with cerebral palsy. We report on these four patients in whom laser reduction of the redundant mucosa led to dramatic improvements in stridor. Secondary benefits to family members and others were equally impressive.

Adolescent↗

The endoscopically measured effects of airway maneuvers and the lateral position on airway patency in anesthetized children with adenotonsillar hypertrophy.

Obstruction of the upper airway is a major challenge for anesthesiologists administering general anesthesia in spontaneously breathing children with adenotonsillar hypertrophy. Lateral positioning is a simple treatment for obstructive sleep apnea. In this study, we examined the effects of body position shifting and common airway maneuvers such as chin lift and jaw thrust on airway patency (stridor score and upper airway dimensions by endoscopy) in anesthetized children scheduled for adenotonsillectomy. Eighteen children aged 1-11 yr were anesthetized with sevoflurane. During spontaneous breathing with 5% sevoflurane and 100% oxygen, upper airway dimensions and stridor score were recorded. After baseline recording, chin lift and jaw thrust were performed in both the supine and the lateral decubitus position. Chin lift, jaw thrust, and lateral position increased the airway dimensions and improved the stridor score. Moreover, lateral positioning enhanced the effects of these airway maneuvers on airway patency. We concluded that lateral positioning combined with airway maneuvers provided better airway patency for anesthetized children with adenotonsillar hypertrophy.

Adenoidectomy↗

Sound signature for identification of tracheal collapse and laryngeal paralysis in dogs.

The aims of this study were to investigate whether upper airway sounds of dogs with laryngeal paralysis and tracheal collapse have distinct sound characteristics, compared with unaffected dogs. The sounds of 5 dogs with laryngeal paralysis and 5 dogs with tracheal collapse were recorded. Honking sound appeared as predominant clinical signs in dogs with tracheal collapse. Laryngeal stridors appeared as predominant clinical signs in dogs with experimentally produced laryngeal paralysis by resection of laryngeal nerve, in which two types of stridor, I and II, were recorded. All these sounds were analyzed using sound spectrogam analysis. There were significant differences in duration (sec), intensity (dB), pitch (Hz), first formant (Hz), second formant (Hz), third formant (Hz), fourth formant (Hz) of sounds between the normal bark and two types of stridor or honking sound, indicating that the sound analysis might be a useful diagnostic modality for dogs with tracheal collapse and laryngeal paralysis.

Animals↗

Functional upper airway obstruction. Psychogenic pharyngeal constriction.

A 15-year-old boy, known to have asthma, developed acute inspiratory airway obstruction with marked stridor. Spirometry indicated extrathoracic airway obstruction and a bronchofiberoptic examination disclosed narrowing in the hypopharynx. After administration of sedatives, the stridor suddenly disappeared. Psychotherapy decreased the frequency of subsequent stridor attacks. It is suggested that psychogenic pharyngeal constriction may have caused the upper airway obstruction with respiratory distress.

Adolescent↗

Reintubation as an outcome predictor in trauma patients.

STUDY OBJECTIVE: Determine reintubation rate, identify its cause, and detail adverse outcomes from reintubation. DESIGN: Retrospective review of extubation failures in the trauma ICU. SETTING: University hospital and regional trauma center. PATIENTS: Four hundred five patients arriving intubated or requiring intubation during hospitalization after 2,516 traumatic injury admissions over 18 months. INTERVENTIONS: None. RESULTS: Reintubation incidence was 7% (27 times per 405 patients). Comparative mortality of the reintubated group (2/24 = 8%) is similar to overall trauma center mortality (224/2516 = 6.5%), but less than the cohort of patients admitted to the hospital intubated (63/405 = 16%). Reintubated patients had an increased frequency of stridor than reported previously (33%), and an increased tracheostomy rate (62% vs 30%). Stridor was not predictable from injury severity score, Glasgow coma score, age, sex, length of intubation, or place of intubation. Pulmonary complications (atelectasis, tracheobronchitis, pneumonia) developed in half of reintubated patients; stridorous patients did not have an increased rate of pulmonary complications. CONCLUSION: Reintubation in trauma ICU patients does not predict poor outcome.

Adolescent↗

Chronic aspiration without gastroesophageal reflux as a cause of chronic respiratory symptoms in neurologically normal infants.

OBJECTIVE: To describe 13 neurologically normal infants with chronic respiratory symptoms who had swallowing dysfunction with silent chronic aspiration without gastroesophageal reflux (GER) as the cause of their respiratory symptoms. BACKGROUND: Infants with neurologic disorders and infants with GER are known to have chronic respiratory symptoms. Isolated swallowing dysfunction and aspiration without GER in neurologically normal infants have not been widely reported. DESIGN: Retrospective chart review. SETTING: A tertiary pulmonary-care center at a children's hospital. PATIENTS: One hundred twelve otherwise healthy infants referred for respiratory symptoms who underwent esophageal pH studies and videofluoroscopic swallow studies (VSSs). METHODS: The records of infants referred between January 1997 and December 1999 to the Department of Pediatric Pulmonology who underwent 24-h esophageal pH monitoring and VSS as part of an evaluation for recurrent stridor and/or wheezing were reviewed. Significant GER was diagnosed if the percentage of time with esophageal pH < 4 was > 6%. Infants included in the study presented with recurrent respiratory symptoms, were born at term, were neurologically normal, had normal results of esophageal pH studies, but had abnormal results of VSSs (n = 13). RESULTS: All 13 infants presented with a variety of recurrent respiratory symptoms including wheezing and intermittent stridor. Ten of 13 infants had spitting and/or choking episodes with feeding. The mean (+/- SD) age at the onset of symptoms was 2.0 +/- 1.6 months, and the mean age at VSS was 5.9 +/- 3.4 months. All 13 infants had normal results of 24-h esophageal pH studies but had abnormal results for VSSs. All infants had evidence of swallowing dysfunction and direct silent aspiration of liquids with thin consistency. Six infants also were aspirating liquids with thick and/or semi-thick consistencies. None of the infants had evidence of structural anomalies on esophagograms. Nine infants were treated with thickened food, and in four infants oral feedings were stopped. Three of these infants required nasojejunal feeding, and one infant required gastrostomy tube feeding. VSSs were repeated every 3 months. In all infants, swallowing dysfunction resolved within 3 to 9 months. All infants tolerated the resumption of oral feeding. Videofluoroscopic documentation of the resolution of aspiration was followed by the resolution of respiratory symptoms in all infants. CONCLUSION: There is a subgroup of otherwise healthy infants, presenting with wheeze and/or stridor, who have isolated swallowing dysfunction and silent aspiration as the cause of their respiratory symptoms.

Chronic Disease↗

Trials of corticosteroids to prevent postextubation airway complications.

We identified three randomized controlled trials (RCTs) that addressed whether preextubation steroid administration reduces postextubation complications in children. The pooled analysis of primary extubation in children demonstrated significantly less stridor (relative risk [RR], 0.57; 95% confidence interval [CI], 0.40 to 0.81) and a trend toward less reintubation (RR, 0.50; 95% CI, 0.02 to 13.87) with corticosteroids. One non-RCT in children who had failed extubation the first time found a significant reduction in duration of prolonged reintubation (> or = 6 days) and in failed reextubations. The four RCTs in adults reported very low reintubation rates, and no conclusions can be drawn. Only one RCT assessed postextubation stridor and found little difference. Overall, we found that corticosteroids decreased the risk of postextubation stridor in children by about 40%. However, the effect of corticosteroids in children and adults to reduce postextubation complications such as reintubation is uncertain.

Adrenal Cortex Hormones↗

Post-pneumonectomy syndrome. Surgical correction using Silastic implants.

A post-right pneumonectomy syndrome is described which manifests symptoms of exertional dyspnea and inspiratory stridor on rapid inspiration. These symptoms were associated with marked rightward and posterior deviation of the trachea, over-distention of the left lung with its herniation into the right side of the chest and kinking of the left lower lobe bronchus. At the time of surgery, the tracheal deviation, lung herniation and the kink in the left lower lobe bronchus were immediately corrected by releasing the adhesions between the malpositioned structures and the right chest wall. To maintain the corrected positions, Silastic implants totalling a volume of 990 ml were placed into the space created in the right chest. Following surgery, exertional dyspnea was present with only extraordinary activity, and inspiratory stridor was eliminated. The patient remains asymptomatic three years following surgical correction, and is able to carry on a normal and productive life. We conclude that a syndrome associated with marked exertional dyspnea and inspiratory stridor might develop in situations of marked tracheal shift and overdistention of the remaining lung following right pneumonectomy.

Adult↗