Comparison of the Berman Intubating Airway and the Williams Airway Intubator for fibreoptic orotracheal intubation in anaesthetised patients

Sixty patients with no clinical indicators of a difficult airway were selected to undergo a fibreoptic assessment after induction of general anaesthesia using both the Berman Intubating Airway and the Williams Airway Intubator. The bronchoscopic view and ease of railroading a tracheal tube during fibreoptic orotracheal intubation were studied. The bronchoscopic views obtained by the Berman Airway and the Williams Airway were significantly different (p < 0.008, test of symmetry). The estimated odds ratio of obtaining an obstructed path was 3.06 times higher for the Berman than the Williams Airway. However, if the glottis could be reached with the bronchoscope, there was no significant difference in the degree of ease of intubation between the two airways.

The effects of salbutamol, beclomethasone, and dexamethasone on fibronectin expression by cultured airway smooth muscle cells

Possible mechanisms of adverse drug effects in asthma include worsening of cellular hyperplasia and stimulation of extracellular matrix deposition. In this study, salbutamol, dexamethasone and beclomethasone were investigated to ascertain their ability to induce mitogenesis and stimulate fibronectin expression in cultured canine airway smooth muscle cells. In cells maintained in serum-free media for 72 h, salbutamol(1 nM-10 mu M) caused mitogenesis. The control cells had 2.57 +/- 0.34 x 10(5) cells per mi (mean +/- SEM, N = 13), while salbutamol (1 mu M) caused a maximal increase in cell number to 3.57 +/- 0.23 x 10(5) cells/ml (P < 0.01). In cells stimulated to replicate by addition of either fetal bovine serum or canine serum, no additional mitogenic effect of salbutamol was seen. Salbutamol did not have a detectable quantitative effect on fibronectin matrix expression. The glucocorticoids, beclomethasone and dexamethasone, significantly altered fibronectin expression by cultured airway smooth muscle cells. Beclomethasone increased fibronectin expression, while dexamethasone decreased expression.

Antagonism by NKP608 of substance P-induced plasma protein exudation in a novel preparation of perfused trachea in rats and guinea-pigs in vivo

Objective: To examine whether NKP608, a novel 1-benzoyl-2-benzyl-4-aminopiperidine NK1 receptor antagonist, inhibits substance P (SP)-induced airway plasma protein exudation in vivo. Material: Anaesthetised English shorthair guinea-pigs and Wistar rats. Treatment: Tachykinin peptides were applied topically onto the trachea and antagonists administered intravenously. Methods: Tracheal segments isolated in situ were perfused with saline and plasma-derived protein assayed in the perfusate. Results: SP (1 muM) caused plasma protein exudation, which was abolished by an NK1 antagonist (RP 67580, 1.75 mumol/kg) but unaffected by an NK2 antagonist (SR 48968, 1.75 mumol/kg) indicating the response is NK1-receptor-mediated. This was confirmed with a response to an NK1 agonist ([Sar(9), Met(O-2)(11)]-SP, 1 muM) but none to an NK2 agonist ([betaAla(8)]-neurokinin A(4-10), 1 muM). NKP608 inhibited SP responses with estimated ID50 values (mumol/kg) of 0.0044 (guinea-pigs) and 0.19 (rats). Conclusions: NKP608 is an antagonist in vivo of NK1 receptor-induced tracheal plasma protein exudation and is more potent in guinea-pigs than rats.

Electrolyte transport in the mouse trachea: No evidence for a contribution of luminal K+ conductance

Recent studies on frog skin acini have challenged the question whether Cl- secretion or Na+ absorption in the airways is driven by luminal K+ channels in series to a basolateral K+ conductance. We examined the possible role of luminal K+ channels in electrolyte transport in mouse trachea in Ussing-chamber experiments. Tracheas of both normal and CFTR (-/-) mice showed a dominant amiloride-sensitive Na+ absorption under both, control conditions and after cAMP-dependent stimulation. The lumen-negative transepithelial voltage was enhanced after application of IBMX and forskolin and Cl- secretion was activated. Electrolyte secretion induced by IBMX and forskolin was inhibited by luminal glibenclamide and the blocker of basolateral Na(+)2Cl(-)K(+) cotransporter azosemide. Similarly, the compound 29313, a blocker of basolateral KCNQ1/KCNE3 K+ channels effectively blocked Cl- secretion when applied to either the luminal or basolateral side of the epithelium. RT-PCR analysis suggested expression of additional K+ channels in tracheal epithelial cells such as Slo1 and Kir6.2. However, we did not detect any functional evidence for expression of luminal K+ channels in mouse airways, using luminal 29313, clotrimazole and Ba2+ or different K+ channel toxins such as charybdotoxin, apamin and alpha-dendrotoxin. Thus, the present study demonstrates Cl- secretion in mouse airways, which depends on basolateral Na(+)2Cl(-)K(+) cotransport and luminal CFTR and non-CFTR Cl- channels. Cl- secretion is maintained by the activity of basolateral K+ channels, while no clear evidence was found for the presence of a luminal K+ conductance.

Gene complementation of airway epithelium in the cystic fibrosis mouse is necessary and sufficient to correct the pathogen clearance and inflammatory abnormalities

Increasingly, cystic fibrosis (CF) is regarded as an inflammatory disorder where the response of the lung to Pseudomonas aeruginosa is exaggerated as a consequence of processes mediated by the product of the CF gene, CFTR. Of importance to any gene-replacement strategy for treatment of CF is the identification of the cell type(s) within the lung milieu that need to be corrected and an indication whether this is sufficient to restore a normal inflammatory response and bacterial clearance. We generated G551D CF mice transgenically expressing the human CFTR gene in two tissue compartments previously demonstrated to mediate a CFTR-dependent inflammatory response: lung epithelium and alveolar macrophages. Following chronic pulmonary infection with P. aeruginosa, CF mice with epithelial-expressed but not macrophage-specific CFTR showed an improvement in pathogen clearance and inflammatory markers compared with control CF animals. Additionally, these data indicate the general role for epithelial cell-mediated events in the response of the lung to bacterial pathogens and the importance of CFTR in mediating these processes.

Systematic review of the role of pre-oxygenation for tracheal suctioning in ventilated newborn infants

Pre-oxygenation for endotracheal suctioning for mechanically ventilated infants is routine practice in many neonatal intensive care units. In the present systematic review the evidence to support its use is discussed and the authors conclude that no confident recommendations can be made from the results of this review.

An evaluation of continuous positive airway pressure (CPAP) therapy in the treatment of hypernasality following traumatic brain injury - A report of 3 cases

Objective: To evaluate the effectiveness of continuous positive airway pressure (CPAP) therapy in the treatment of hypernasality following traumatic brain injury (17111). Design: An A-B-A experimental research design. Assessments were conducted prior to commencement of the program, midway, immediately posttreatment, and 1 month after completion of the CPAP therapy program. Participants: Three adults with dysarthria and moderate to severe hypernasality subsequent to TBI. Outcome Measures: Perceptual evaluation using the Frenchay Dysarthria Assessment, the Assessment of Intelligibility of Dysarthric Speech, and a speech sample analysis, and instrumental evaluation using the Nasometer. Results: Between assessment periods, varying degrees of improvement in hypernasality and sentence intelligibility were noted. At the 1-month post-CPAP assessment, all 3 participants demonstrated reduced nasalance values, and 2 exhibited increased sentence intelligibility. Conclusions: CPAP may be a valuable treatment of impaired velopharyngeal function in the TBI population.

Two new tools for assessing patients' knowledge and beliefs about obstructive sleep apnea and continuous positive airway pressure therapy

Background and purpose: Patients' knowledge and beliefs about their illnesses are known to influence a range of health related variables, including treatment compliance. It may, therefore, be important to quantify these variables to assess their impact on compliance, particularly in chronic illnesses such as Obstructive Sleep Apnea (OSA) that rely on self-administered treatments. The aim of this study was to develop two new tools, the Apnea Knowledge Test (AKT) and the Apnea Beliefs Scale (ABS), to assess illness knowledge and beliefs in OSA patients. Patients and methods: The systematic test construction process followed to develop the AKT and the ABS included consultation with sleep experts and OSA patients. The psychometric properties of the AKT and ABS were then investigated in a clinical sample of 81 OSA patients and 33 healthy, non-sleep disordered adults. Results: Results suggest both measures are easily understood by OSA patients, have adequate internal consistency, and are readily accepted by patients. A preliminary investigation of the validity of these tools, conducted by comparing patient data to that of the 33 healthy adults, revealed that apnea patients knew more about OSA, had more positive attitudes towards continuous positive airway pressure (CPAP) treatment, and attributed more importance to treating sleep disturbances than non-clinical groups. Conclusions: Overall, the results of psychometric analyses of these tests suggest these measures will be useful clinical tools with numerous beneficial applications, particularly in CPAP compliance studies and apnea education program evaluations. (C) 2004 Elsevier B.V. All rights reserved.

Pressure support ventilation with the ProSeal (R) laryngeal mask airway. A comparison of sevoflurane, isoflurane and propofol

Background and objective: There are no data about the influence of anaesthetics on cardiovascular variables during pressure support ventilation of the lungs through the laryngeal mask airway. We compared propofol, sevoflurane and isoflurane for maintenance of anaesthesia with the ProSeal (R) laryngeal mask airway during pressure support ventilation. Methods: Sixty healthy adults undergoing peripheral musculo-skeletal surgery were randomized for maintenance with sevoflurane end-tidal 29%, isoflurane end-tidal 1.1% or propofol 6 mg kg(-1) h(-1) in oxygen 33% and air. Pressure support ventilation comprised positive end-expiratory pressure set at 5 cmH(2)O, and pressure support set 5 cmH(2)O above positive end-expiratory pressure. Pressure support was initiated when inspiration produced a 2 cmH(2)O reduction in airway pressure. A blinded observer recorded cardiorespiratory variables (heart rate, mean blood pressure, oxygen saturation, air-way occlusion pressure, respiratory rate, expired tidal volume, expired minute volume and end-tidal CO2), adverse events and emergence times. Results: Respiratory rate and minute volume were 10-21% lower, and end-tidal CO2 6-11% higher with the propofol group compared with the sevoflurane or isoflurane groups, but otherwise cardiorespiratory variables were similar among groups. No adverse events occurred in any group. Emergence times were longer with the propofol group compared with the sevoflurane or isoflurane groups (10 vs. 7 vs. 7 min). Conclusion: Lung ventilation is less effective and emergence times are longer with propofol than sevoflurane or isoflurane for maintenance of anaesthesia during pressure support ventilation with the ProSeal (R) laryngeal mask airway. However, these differences are small and of doubtful clinical importance.