Predicting the severity of congenital high airway obstruction syndrome

Background

Congenital high airway obstruction syndrome (CHAOS) is caused by complete or near-complete obstruction of the fetal airway. Obstruction sets in motion a sequence of events that can ultimately lead to fetal demise. However, on rare occasions in utero airway decompression occurs, reversing syndromic findings and improving the prognosis. In our relatively large series of CHAOS patients, we have observed a spectrum of clinical severity. The aim of this study was to identify the prenatal characteristics of CHAOS predictive of a milder postnatal course.

Methods

The medical charts of all fetuses observed at our institution with the diagnosis of CHAOS were reviewed for radiologic findings, delivery information, perinatal course, autopsy or discharge report, and long-term follow-up.

Results

Between 1996 and 2008, 12 fetuses with CHAOS were identified. Four fetuses had no evidence of hydrops on initial imaging. Of the 8 fetuses displaying hydrops, 3 were terminated, 2 died in utero, and 1 with multiple anomalies died at birth. Six fetuses were delivered via the ex utero intrapartum therapy procedure for attempted salvage, and 5 of the 6 survived the neonatal period including all 4 fetuses without hydrops. Serial prenatal imaging demonstrated less severe signs of CHAOS in 3 fetuses, and in 2 of them, direct laryngoscopy revealed a tiny opening in the airway. All 3 fetuses that showed improvement on serial imaging survived the neonatal period and were discharged home by 2-10 weeks of age.

Conclusions

Although the natural history of CHAOS is variable, trends in prenatal ultrasound findings are highly predictive of postnatal outcome and are a valuable guide to prenatal counseling.     

Relation of measures of asthma severity and response to treatment to outcome in acute severe asthma.

BACKGROUND: It would be helpful if patients with asthma who require admission to hospital for an acute attack could be identified. METHODS: The relation between the severity of an attack of asthma as determined by admission assessment and the eventual outcome was studied in 52 asthmatic patients aged 14 to 44 years and admitted to an asthma emergency room. The patient's history, including medication and previous admissions to hospital, was recorded and a clinical assessment, including a full inspiratory and expiratory flow-volume loop, was performed on four occasions: on admission, at two hours and at 12-18 hours after the start of a standardised treatment, and two weeks later on an outpatient basis. Patients who were discharged and who had an uneventful follow up at the two week assessment were defined as good responders. Patients who had to be admitted to hospital after 12 to 18 hours or were readmitted during the two weeks, or both, were defined as poor responders. RESULTS: Thirty eight patients were good responders and 14 were poor responders (seven admitted at 12 to 18 hours, seven returned to hospital). All four patients with a raised arterial carbon dioxide tension (PaCO2) (> or = 6 kPa) and the three with cyanosis were in the poor responder group, and this group had lower peak expiratory flow (PEF) values (21% v 30% predicted) on admission. There was, however, considerable overlap in PEF between the two groups and no clinical measure was able to distinguish between the good and the poor responders reliably. Poor responders had a history of more chronic systemic steroid administration, regular use of inhaled beta agonists, and asthma related hospital admissions. Nearly all the subjects showing a good response to standardised treatment had a PEF > 75% predicted and an FEV1 > 65% predicted 12 to 18 hours after the start of treatment. CONCLUSION: Prediction of outcome at admission was not possible in individual patients. A history of poor long term control of asthma, a PEF < 30% of predicted, a PaCO2 > or = 6 kPa, the presence of cyanosis, and lack of early response to treatment indicated a group of asthmatic patients who are less likely to respond to conventional emergency treatment over a short period.     

Imaging sites of airway obstruction and measuring functional responses to bronchodilator treatment in asthma.

The sites of airway obstruction and dilatation after terbutaline administration were studied by inhalation imaging and pulmonary function tests in 12 stable asthmatic patients. Inhaled terbutaline as a therapeutic aerosol decreased airway resistance (Raw) and improved radioaerosol (Ae) images in nine, delta V max50 in three, and xenon (Xe) images in five of 12 subjects, suggesting that its predominant site of action was on major airways. Subcutaneously injected terbutaline improved Raw, delta V max50, and Ae images in 11 and Xe images in eight subjects indicating that it released bronchospasm in the major and minor airways. These findings in asthma suggest that aerosol and Xe imaging procedures are sensitive indicators of large and small airway obstruction respectively.     

Effect of betamethasone on airway obstruction and bronchial response to salbutamol in prednisolone resistant asthma.

Twelve patients with chronic severe asthma, having previously shown an FEV1 increase of less than 20% of the predicted value with prednisolone treatment (20-60 mg daily for 10 days), took part in a double blind crossover comparison of equipotent anti-inflammatory doses of betamethasone and prednisolone. Betamethasone (8 mg) and prednisolone (40 mg) were administered daily for 10 days with a washout period of 10 days between. In this first part of the study betamethasone was administered intramuscularly and prednisolone orally. Placebo injections and tablets were used. Mean FEV1 was not significantly different before each period. There was a significant increase in FEV1 while they were taking betamethasone but not prednisolone. Individual analysis of the data showed that FEV1 increased with betamethasone in nine patients and remained stable or decreased in three. During treatment with prednisolone baseline FEV1 increased moderately in three patients (FEV1 0.3, 0.5 and 0.6 l) and remained stable or decreased in nine. There was no significant difference between the bronchodilator responses to cumulative doses of inhaled salbutamol when they were measured immediately before, on the last day of treatment with each steroid, and between steroid treatment periods. The same protocol was followed four months later in five of the 12 patients but both drugs were administered orally on this occasion. Similar results were obtained. The greater effect of betamethasone on bronchial obstruction may be due to its longer biological half life or to some unidentified property of its metabolites. The bronchial response to inhaled beta 2 agonist appears not to be influenced by either steroid in these patients.     

Relation of the hypertonic saline responsiveness of the airways to exercise induced asthma symptom severity and to histamine or methacholine reactivity.

BACKGROUND: Conflicting views exist over whether responsiveness of the airways to hypertonic saline relates to non-specific bronchial hyperresponsiveness measured by histamine or methacholine challenge. The bronchoconstrictor responses to exercise and hypertonic saline are reported to be closely related, but the relationship between the symptoms of exercise induced asthma and airway responsiveness to hypertonic saline is not known. METHODS: In 29 asthmatic patients with a history of exercise induced asthma, the response to an ultrasonically nebulised hypertonic saline (3.6% sodium chloride) aerosol, measured as the volume of hypertonic saline laden air required to produce a fall in forced expiratory volume in one second (FEV1) of > or = 20% (PD20), was compared with the concentration of histamine (PC20; group 1) and methacholine (PC20; group 2) producing a 20% fall in baseline FEV1 and exercise induced asthma symptom severity score (groups 1 and 2). The hypertonic responsiveness was determined in a dose-response manner to a maximum dose of 310 1 and the exercise induced asthma symptom severity was scored on a scale of 0-5. RESULTS: Of the 29 patients, 23 (79%) were responsive to the hypertonic saline, with PD20 values ranging from 9 to 310 1. A significant correlation was found between the PD20 hypertonic saline and the exercise induced asthma symptom score. There was no significant correlation between the PD20 response to hypertonic saline and the histamine PC20 or methacholine PC20. The exclusion of those subjects who failed to respond to hypertonic saline improved the relationship between hypertonic saline and methacholine PC20. No significant correlation was found between the exercise induced asthma symptom score and histamine PC20 or methacholine PC20. CONCLUSION: These findings suggest that hypertonic saline responsiveness bears a closer relationship to the severity of exercise induced asthma symptoms than to the non-specific bronchial hyperresponsiveness measured by histamine or methacholine reactivity.     

Acute airway obstruction secondary to achalasia mega-oesophagus

Acute airway obstruction is a very rare presentation of achalasia. We report the case of a 78-year-old woman with previously undiagnosed achalasia who presented with acute respiratory distress and stridor due to tracheal compression by mega-oesophagus. Anaesthetists and physicians caring for patients with achalasia must be aware of the need for emergency oesophageal decompression in this rare and life-threatening condition.     

Relationship between the acid-induced cough response and airway responsiveness and obstruction in children with asthma.

BACKGROUND: In children with asthma little is known about the direct effect of the bronchoconstrictor and bronchodilator response on the cough threshold, or the relationship between bronchial responsiveness and the cough threshold. A study was undertaken to determine the effect of histamine-induced bronchoconstriction and salbutamol-induced bronchodilatation on the cough threshold in response to inhaled acetic acid, and to examine the relationship between the acetic acid cough threshold and bronchial hyperresponsiveness to histamine in children with asthma. METHODS: Nineteen children with asthma (16 boys) of mean (SE) age 10.6 (0.6) years were enrolled in the study. On day 1 each underwent a histamine inhalation challenge to determine the provocative concentration causing a fall in forced expiratory volume in one second (FEV1) of more than 20% (PC20) as an index of individual bronchial hyperresponsiveness. On day 2 the acetic acid cough threshold was determined before and just after the inhalation of the PC20 concentration of histamine, and then salbutamol (1 mg/m2) was inhaled to relieve the bronchoconstriction. Ten of the 19 patients (eight boys) of mean age 12.2 (0.7) years also tried acetic acid inhalation challenge just after salbutamol inhalation. RESULTS: There was no relationship between the bronchial responsiveness to histamine and acetic acid cough threshold in these patients. The acetic acid cough threshold after histamine inhalation was similar to that before histamine, although FEV1 decreased after histamine. In the 10 patients who also tried acetic acid inhalation challenge after salbutamol the cough threshold did not change. CONCLUSIONS: These findings suggest that acid-induced cough sensitivity and bronchomotor tone are independently regulated in children with asthma.     

Postoperative airway obstruction after airway tumor debulking

Postoperative airway obstruction is a relatively common complication after anesthesia, occurring most often after head and neck surgery. We present a case of postoperative airway obstruction in a patient who underwent airway tumor debulking. This case demonstrates that, in high-risk patients, despite the traditional methods of determining eligibility for extubation, postoperative airway obstruction can still occur, and alternative means of extubation should be considered.