Mean Airway Research Articles

Comparison of airway pressure release ventilation (APRV) versus biphasic positive airway pressure (BIPAP) ventilation in COVID-19 associated ARDS using transpulmonary pressure monitoring

BackgroundAPRV has been used for ARDS in the past. Little is known about the risk of ventilator- induced lung- injury (VILI) in APRV vs. BIPAP in the management of in COVID19-associated ARDS (CARDS). This study aimed to compare transpulmonary pressures (TPP) in APRV vs. BIPAP in CARDS in regard to lung protective ventilator settings.MethodsThis retrospective, monocentric cohort study (ethical approval: 21-1553) assessed all adult ICU- patients with CARDS who were ventilated with BIPAP vs. APRV and monitored with TPP from 03/2020 to 10/2021. Ventilator-settings / -pressures, TPP, hemodynamic and arterial blood gas parameters were compared in both modes.Results20 non- spontaneously breathing patients could be included in the study: Median TPPendexpiratory was lower / negative in APRV (-1.20mbar; IQR − 4.88 / +4.53) vs. positive in BIPAP (+ 3.4mbar; IQR + 1.95 / +8.57; p < .01). Median TPPendinspiratory did not differ. In APRV, mean tidal- volume per body- weight (7.05 ± 1.28 vs. 5.03 ± 0.77 ml; p < .01) and mean airway- pressure (27.08 ± 1.67 vs. 22.68 ± 2.62mbar; p < .01) were higher. There was no difference in PEEP, peak-, plateau- or driving- pressure, compliance, oxygenation and CO2- removal between both modes.ConclusionDespite higher tidal- volumes / airway-pressures in APRV vs. BIPAP, TPPendinspiratory was not increased. However, in APRV median TPPendexpiratory was negative indicating an elevated risk of occult atelectasis in APRV- mode in CARDS. Therefore, TPP- monitoring could be a useful tool for monitoring a safe application of APRV- mode in CARDS.

Determination of optimal positive end-expiratory pressure using electrical impedance tomography in infants under general anesthesia: Comparison between supine and prone positions.

This study determined the optimal positive end-expiratory pressure levels in infants in supine and prone positions under general anesthesia using electrical impedance tomography (EIT). This prospective observational single-centre study included infants scheduled for surgery in the prone position. An electrical impedance tomography sensor was applied after inducing general anesthesia. The optimal positive end-expiratory pressure in the supine position was determined in a decremental trial based on EIT and compliance. Subsequently, the patient's position was changed to prone. Electrical impedance tomography parameters, including global inhomogeneity index, regional ventilation delay, opening pressure, the centre of ventilation, and pendelluft volume, were continuously obtained up to 1 h after prone positioning. The optimal positive end-expiratory pressure in the prone position was similarly determined. Data from 30 infants were analyzed. The mean value of electrical impedance tomography-based optimal positive end-expiratory pressure in the prone position was significantly higher than that in the supine position [10.9 (1.6) cmH2O and 6.1 (0.9) cmH2O, respectively (p < .001)]. Significant differences were observed between electrical impedance tomography- and compliance-based optimal positive end-expiratory pressure. Peak and mean airway, plateau, and driving pressures increased 1 h after prone positioning compared with those in the supine position. In addition, the centre of ventilation for balance in ventilation between the ventral and dorsal regions improved. The prone position required higher positive end-expiratory pressure than the supine position in mechanically ventilated infants under general anesthesia. EIT is a promising tool to find the optimal positive end-expiratory pressure, which needs to be individualized.

Morphological Changes of the Epipharynx as a Result of Rapid Maxillary Expansion in Children

Rapid maxillary expansion（RME）is a technique used to treat dental malalignment. Consensus has yet to be reached changes in the epipharyngeal region associated with RME. The objective of this study was to ascertain the morphological changes that occur in the epipharyngeal region as a result of RME. In the present study, a comparative investigation of the pharyngeal tonsils and the epipharyngeal airway on lateral cephalograms scanned before and after RME was therefore performed. Fourteen patients who underwent orthodontic treatment for dental malalignment by RME were included. The mean length of pharyngeal tonsil（A）was 114.65 pixels before RME and 108.64 pixels after RME. The mean value of epipharyngeal space（N）was 210.72 pixels before RME and 233.95 pixels after RME. The mean A/N ratio was 0.547 before RME and 0.466 after RME. The mean pharyngeal tonsil（Pt）area was 16181.14 pixels before RME and 16407.71 pixels after RME. The mean airway（Air）area was 12488.96 pixels before RME and 16040.64 pixels after RME. The mean Pt / Ep（Ep = Pt + Air）area was 0.570 before RME and 0.502 after RME. In this study showed that the A/N and Pt/Ep ratios decreased significantly after RME. The N and Air area values also increased significantly, but there were no significant changes in the A and Pt area values. It was concluded that the decrease in the A/N and Pt/Ep ratios were due to the changes in the N and Air area values.

Evaluation and quantification of airway changes in Class II division 1 patients undergoing myofunctional therapy using twin block appliance

BackgroundThe purpose of the present study was to determine the airway changes in skeletal class II division 1 malocclusion patients with mandibular retrognathism, treated with Twin-Block (TB) appliance. MethodsAirway assessment was carried for twelve patients (mean age 11.7 ± 1.1 years) who underwent myofunctional therapy using TB appliance for correction of skeletal class II division 1 malocclusion with mandibular retrognathism. Acoustic pharyngometry (AP) was used to assess and quantify the comparative changes in the upper airway, pretreatment and posttreatment. ResultsData acquired was subjected to appropriate statistical analysis. The paired ‘t’ test was used to compare pre-treatment (T0) and after the positive pterygoid response (T1). TB appliance increased mean minimum airway area by 0.28 ± 0.25 cm2 and mean airway by 0.47 ± 0.44 cm2 with 95% CI. Posttreatment minimum airway and mean area changes were found to be statistically significant (P-value<0.01). ConclusionTB appliance therapy has a positive effect on upper airway and is beneficial for the treatment of sleep-related disorders associated with Class II division 1 malocclusion for achieving positive functional changes, esthetics, and healthier quality of life.

Abstract 200: Argon Reduces the Vasoconstrictive Effects of Phenylephrine in a Rat Isolated Lung Model

Introduction: Even with cardiopulmonary resuscitation (CPR), most patients having an out-of-hospital cardiac arrest (CA) either die or endure severe neurological damage. Ventilation with the noble gas Argon (Ar) during CPR improved hemodynamics in a porcine CA model. Hypothesis: Ventilation with Ar attenuates vasoconstriction by phenylephrine, an α 1 agonist, in a rat isolated lung model. Methods: All procedures were approved by our Institutional Animal Care and Use Committee and performed according to the guidelines of the National Research Council’s Guide for the Humane Care and Use of Laboratory Animals. The lungs of adult male Sprague Dawley rats (250-350 g) were isolated and positive-pressure ventilated with a tidal volume of 10 mL/kg body weight (BW) and a respiration rate of 30 breaths/minute. Both the pulmonary artery and left atrium were cannulated for in- and outflow and the lungs perfused at a constant flow of 40 mL/kg BW with a 4% albumin physiological saline solution (NaCl 119 mM, NaHCO 3 24 mM, Glucose 5.5 mM, CaCl 2 1.6 mM, KCl 4.7 mM, MgSO 4 1.17 mM, NaPO 4 1.18 mM) . The mean arterial pressure (MAP) and airway pressure were recorded continuously. The control (C) group (n=6) was ventilated with 65% N 2 , 5% CO 2 , 30% O 2 , the Ar group (n=7) with 65% Ar, 5% CO 2 , 30% O 2 . Baseline (bl) readings for 10 minutes were followed by increasing phenylephrine concentrations from 10 -7 M to 10 -3 M every 5 minutes. Statistics: Student’s t-Test with *p&lt; 0.05. Results: When ventilating with Ar, we observed lower MAPs. For the phenylephrine concentrations 10 -5 M C: 1.31 ± 0.02 vs Ar: 1.21 ± 0.03 and 10 -4 C: 1.48 ± 0.02 vs Ar: 1.32 ± 0.05 the differences were significant. Conclusion: Ventilation with 65% Ar significantly dilated preconstricted pulmonary vessels in an ex-vivo rat lung model. Pulmonary vasodilation might aid to increased cardiac output during CPR.

Ambient Noise Production by High-Frequency Neonatal Ventilators

To assess sound levels of 4 high-frequency neonatal ventilators to determine whether there is a safety benefit in using modern high-frequency ventilators compared with older models. We performed a bench study comparing noise production of the Sensormedics 3100A Oscillator, Bunnell Life Pulse Jet Ventilators Model 203 and Model 204, and Dräger VN500 in high-frequency mode. A wide range of ventilation settings was examined. All measurements were performed in triplicate using a high-fidelity sound meter, with data analyzed using ANOVA and regression analyses. The Dräger ventilator was quietest overall, with average sound levels of 49.8 ± 0.49 dB across all settings. The average noise from the Sensormedics was 53.6 ± 2.01 dB, for Bunnell Model 203 was 54.1 ± 1.09 dB, and for Bunnell Model 204 was 53.7 ± 1.45 dB. Adjustments made to frequency/rate and mean airway pressure/positive end-expiratory pressure had minimal effect on noise, and increasing amplitude/peak inspiratory pressure resulted in significantly more noise by all ventilators. At all settings, the Sensormedics and Bunnell ventilators were louder than the Dräger, and the difference became greater as amplitude/peak inspiratory pressure was increased. The Dräger VN500 in high-frequency mode produces significantly less noise that both the Sensormedics and Bunnell ventilators. These data suggest that using the Dräger VN500 as a high-frequency ventilator may reduce the potential for adverse outcomes created by ventilator noise.

Efficacy of bronchial blocker outside endotracheal tube for one-lung ventilation in pediatric patients

Objective To evaluate the efficacy of bronchial blocker outside the endotracheal tube for one-lung ventilation (OLV) in pediatric patients. Methods Thirty-eight American Society of Anesthesiologists physical status ⅠorⅡ patients of both sexes, aged 4-8 yr, weighing 14.0-28.6 kg, scheduled for elective thoracic surgery under general anesthesia, were enrolled in this study.The size of tracheal tube was selected according to the endotracheal diameter at the level of clavicle and sternum on chest X-ray.After anesthesia induction, the distal end of the bronchial blocker was bent toward the target bronchus with a videolaryngoscope and then inserted until resistance was felt, and the preselected tracheal tube was inserted with a videolaryngoscope at a depth of (age/2+ 12) cm.The position of the bronchial blocker was adjusted using a bronchofiberscope so that the upper edge of the blue cuff was 0.5-1.0 cm below the carina.The heart rate, mean arterial pressure, SpO2 and airway pressure were recorded, arterial blood gas analysis was performed, and PaCO2 and PaO2 were recorded immediately before OLV (T1), at 30 min after OLV (T2) and at the end of OLV (T3). The intubation time, success rate of intubation at first attempt, displacement of bronchial blocker and occurrence of postoperative laryngeal pain and hoarseness were recorded.The pulmonary collapse was evaluated according to the standard described by Campos. Results Compared with the baseline at T1, PaO2 was significantly decreased and airway pressure was increased at T2, 3 (P 0.05). The average intubation time was(185±38)s.The success rate of intubation at first attempt, rate of bronchial blocker displacement, excellent and good rates of pulmonary collapse and incidence of laryngeal pain and hoarseness were 95%, 16%, 100% and 11%, respectively. Conclusion Bronchial blocker outside the endotracheal tube can be effectively used for OLV in pediatric patients. Key words: Intubation, intratracheal; Respiration, artificial; Child

Value of the oxygenation index during 1-lung ventilation for predicting respiratory complications after thoracic surgery

PurposeThoracic surgery requiring 1-lung ventilation (OLV) is associated with significant postoperative pulmonary complications (PPCs) due to patient- and surgery-specific risk factors. The aim of this study is to determine whether the oxygenation index (OI) (fraction of inspired oxygen × mean airway pressure/partial pressure of oxygen) during OLV predicts the development of PPC. Materials and methodsThe Society of Thoracic Surgeons General Thoracic Surgery Database at the University of Virginia was used to identify all thoracic cases in 2012 to 2014. All subjects requiring OLV and in whom a blood gas was available for analysis were included. Univariate and multivariate analyses were performed to determine whether the OI predicted the development of PPC. ResultsA total of 296 subjects had OLV with a calculable OI during the study period. Composite PPC were identified in 97 (33%) of subjects. In the PPC group, mortality at 30 days was 7.2%, whereas no deaths were identified in the non-PPC group. In both univariate and multivariate analyses, OI was not predictive of PPC analysis (odds ratio [OR], 1.0; 95% confidence interval [CI], 0.9-1.1; P = .8). The only predictors of mortality were forced expiratory volume (OR, 0.98; 95% CI, 0.96-0.99; P = .03) and diffusion capacity of carbon monoxide (OR, 0.98; 95% CI, 0.96-0.99; P = .03). ConclusionThe calculated OI during OLV is not predictive of PPC in our sample. Additional studies in a larger cohort of patients are needed to identify intraoperative ventilation parameters during OLV that can predict the risk of PPC.

Comparison of pressure-controlled ventilation with volume-controlled ventilation during one-lung ventilation: a systematic review and meta-analysis.

BackgroundNot only arterial hypoxemia but acute lung injury also has become the major concerns of one-lung ventilation (OLV). The use of pressure-controlled ventilation (PCV) for OLV offers the potential advantages of lower airway pressure and intrapulmonary shunt, which result in a reduced risk of barotrauma and improved oxygenation, respectively.MethodsWe searched Medline, Embase, the Cochrane central register of controlled trials and KoreaMedto find publications comparing the effects of PCV with those of volume-controlled ventilation (VCV) during intraoperative OLV in adults. A meta-analysis of randomized controlled trials was performed using the Cochrane Review Methods.ResultsSix studies (259 participants) were included. The PaO2/FiO2 ratio in PCV was higher than in VCV [weighted mean difference (WMD) = 11.04 mmHg, 95 % confidence interval (CI) = 0.30 to 21.77, P = 0.04, I2 = 3 %] and peak inspiratory pressure was significantly lower in PCV (WMD = −4.91 cm H2O, 95 % CI = −7.30 to –2.53, P < 0.0001, I 2 = 91 %). No differences in PaCO2, tidal volume, heart rate and blood pressure were observed. There were also no differences incompliance, plateau and mean airway pressure.ConclusionsOur meta-analysis provided the evidence of improved oxygenation in PCV. However, it is difficult to draw any definitive conclusions due to the fact that the duration of ventilation in the studies reviewed was insufficient to reveal clinically relevant benefits or disadvantages of PCV. Significantly lower peak inspiratory pressure is the advantage of PCV.Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-016-0238-6) contains supplementary material, which is available to authorized users.

High-frequency oscillatory ventilation versus conventional ventilation: hemodynamic effects on lung and heart.

High‐frequency oscillatory ventilation (HFOV) may improve gas exchange in patients who are inadequately ventilated by conventional mechanical ventilation (CV); however, the hemodynamic consequences of switching to HFOV remain unclear. We compared the effects of CV and HFOV on pulmonary vascular conductance and left ventricular (LV) preload and performance at different airway and filling pressures. In anesthetized dogs, we measured LV dimensions, aortic and pulmonary artery (PA) flow, and mean airway (AW) and pericardial pressures. Catheter‐tip pressure manometers measured aortic, LV, left atrial, and PA pressures. The pericardium and chest were closed. At LV end‐diastolic pressure (PLVED) = 5 mmHg and 12 mmHg, PEEP was varied (6 cm H2O, 12 cm H2O, and 18 cm H2O) during CV. Then, at airway pressures equal to those during CV, HFOV was applied at 4 Hz, 10 Hz, and 15 Hz. Increased AW decreased pulmonary vascular conductance. As cardiac output increased, conductance increased. At PLVED = 12 mmHg, conductance was greatest during HFOV at 4 Hz. LV preload (i.e., ALV, our index of end‐diastolic volume) was similar during HFOV and CV for all conditions. At PLVED = 12 mmHg, SWLV was similar during CV and HFOV, but, at PLVED = 5 mmHg and AW 10 cm H2O, SWLV was lower during HFOV than CV. Compared to pulmonary vascular conductance at higher frequencies, at PLVED = 12 mmHg, conductance was greater at HFOV of 4 Hz. Effects of CV and HFOV on LV preload and performance were similar except for decreased SWLV at PLVED = 5 mmHg. These observations suggest the need for further studies to assess their potential clinical relevance.

Anteroposterior Airway Diameter during Sedation for Brain MRI in Children with and without Developmental Disabilities

Objective: Our study objective was to compare the anteroposterior (AP) oropharyngeal airway diameter measured using static MRI images in children with and without developmental disabilities during sedation. Methods: We performed a secondary analysis on a prospective, observational age-matched, 1:2 case-control study of children aged 3 - 10 years who were sedated for brain MRI. AP airway diameters were determined at the level of soft palate (airway_SP) and tongue (airway_T) from midline sagittal images by a single blinded radiologist. Results: Airway diameter was evaluated in 134 controls (C) and 68 cases (D). There was no difference in the overall adverse events (D: 30% C: 32.9%; p = 0.7) as well as hypoxia (D: 10%; C: 9.3%, p = 0.9). There was no significant difference in mean airway_T (D: 10.62 ± 3.48 vs. C: 10.38 ± 3.47; p = 0.64) and airway_SP diameter (D: 4.59 ± 2.36 vs. C: 5.17 ± 3.9; p = 0.14) between the two groups. There was no significant difference in airway_T and airway_SP diameters amongst those who experienced and those who did not experience hypoxia in cases. Amongst controls however, the airway_SP was smaller in those who experienced hypoxia compared to those who did not experience hypoxia. Conclusions: There was no difference in the AP airway_T and airway_SP diameter during sedation using static MRI images in children with and without developmental disabilities. Changes in airway_SP was associated with hypoxia amongst controls in our study cohort.

High-frequency nasal ventilation for 21 d maintains gas exchange with lower respiratory pressures and promotes alveolarization in preterm lambs.

BackgroundShort-term high-frequency nasal ventilation (HFNV) of preterm neonates provides acceptable gas exchange compared to endotracheal intubation and intermittent mandatory ventilation (IMV). Whether long-term HFNV will provide acceptable gas exchange is unknown. We hypothesized that HFNV for up to 21d would lead to acceptable gas exchange at lower inspired oxygen (O2) levels and airway pressures compared to intubation and IMV.MethodsPreterm lambs were exposed to antenatal steroids, and treated with perinatal surfactant and postnatal caffeine. Lambs were intubated and resuscitated by IMV. At ~3h of age, half of the lambs were switched to non-invasive HFNV. Support was for 3d or 21d. By design, PaO2 and PaCO2 were not different between groups.ResultsAt 3d (n=5) and 21d (n=4) of HFNV, fractional inspired O2 (FiO2), peak inspiratory pressure, mean airway, intra-tracheal, and positive end-expiratory pressures, oxygenation index, and Alveolar-arterial gradient were significantly lower than matched periods of intubation and IMV. PaO2/FiO2 ratio was significantly higher at 3d and 21d of HFNV compared to matched intubation and IMV. HFNV led to better alveolarization at 3d and 21d.ConclusionLong-term HFNV provides acceptable gas exchange at lower inspired O2 levels and respiratory pressures compared to intubation and IMV.

Changes in the airway lumen and surrounding parenchyma in chronic obstructive pulmonary disease

BackgroundThe purpose of this study was to examine changes in the airway lumen and parenchyma in relation to lung function in patients with chronic obstructive pulmonary disease (COPD) compared with controls.MethodsWe studied 70 patients with COPD and 15 normal subjects. Using reconstructed computed tomography (CT) images, we traced the bronchial trees and reconstructed 3 cm circle images around the airways exactly perpendicular to the airway axis at the peripheral, middle, and central zones of the bronchi. We measured the number of airways and vessels, the airway inner diameter, and the area of emphysema in the circles, and analyzed the relationship of these image parameters to lung function.ResultsReduced airway numbers and increased upper lobe emphysema were observed even in early spirometric stages in patients with COPD compared with controls. Other findings included decreased airway inner diameter in advanced spirometric stages. The numbers of peripheral zone bronchi, the extent of the middle zone emphysematous area, and the mean airway inner diameter of the airways were the best predictors of spirometric parameters. A portion of the airways in patients with COPD showed a loss of airway patency at middle or central zone bronchi predominantly in the late spirometric stages. Lumen-obliterated bronchial trees could be traced into emphysematous areas showing air trapping.ConclusionCompared with controls, our CT observations in patients with COPD showed that airway lumen and lung parenchyma changes along airways differed by spirometric stage, and these changes were associated with decreased lung function. A portion of CT-identified emphysema in patients with COPD appeared to be due to lumen-obliterated airways in the bronchial tree.

Contributors of the Severity of Airflow Limitation in COPD Patients

of the severity of airflow limitation. Results: Multiple linear regression analysis showed that CT measurements of mean lung density ratio (standardized coefficient β=−0.46; p<0.001), emphysema severity (volume fraction of the lung less than −950 HU at full inspiration; β=−0.24; p<0.001), and airway wall thickness (mean wall area %; β=−0.19, p=0.001), as well as current smoking status (β=−0.14; p=0.009) were independent contributors to FEV1. Conclusion: Mean lung density ratio, emphysema severity, and airway wall thickness evaluated by volumetric CT and smoking status could independently contribute to the severity of airflow limitation in patients with COPD.

High-frequency oscillatory ventilation after cardiac surgery: a treatment for all ages

In a recent issue of Critical Care, Bojan and colleagues [1] reported their experience with early initiation of highfrequency oscillatory ventilation (HFOV) in pediatric cardiac surgery that demonstrated shorter mechanical ventilation times and intensive care stays. Acute lung injury is common in adult patients undergoing surgery, yet there is scant reporting of the intraoperative utility of HFOV [2]. We initiated HFOV in a 49-year-old morbidly obese (body mass index of 69 kg/m 2 ) man who had aortic stenosis, pulmonary hypertension, and decompensated congestive heart failure and who was undergoing aortic valve replacement. Separation from cardiopulmonary bypass (CPB) with inverse-ratio pressure-control ventilation – fraction of inspired oxygen (FiO 2 ) of 1.0 and positive end-expiratory pressure (PEEP) of 18 cm H 2 O – failed because of hypoxia, defi ned as an arterial partial pressure of oxygen (PaO 2 ) of 64 mm Hg. HFOV was initiated (mean pressure airway of 33 cm H 2 O and FiO 2 of 1.0), yielding a PaO 2 of 74 mm Hg and allowing CPB separation. Th e patient was transitioned to conventional ventilation on postoperative day 3 and was extubated on postoperative day 5. Th is adult patient benefi ted from HFOV, as did the pediatric population of Bojan and colleagues. Continuous positive intrathoracic pressure is a concern as it may impede venous return and thereby limit cardiac output (CO) [3]. However, the transition from ventilation with PEEP to HFOV usually results in signifi cant changes in oxygenation/ventilation but not in CO [4]. In patients with pulmonary hypertension, HFOV has been demonstrated to increase CO and decrease pulmonary vascular resistance [5]. For our patient, HFOV allowed improved oxygenation without aff ecting hemodynamics. HFOV may be a safe and eff ective therapy to improve oxygenation/ventilation in patients undergoing cardiac surgery and possibly is underused because of unfounded hemodynamic concerns. HFOV needs exploration as a rescue tool after CPB for patients with hypoxia.

High-frequency oscillation combined with arteriovenous extracorporeal lung assist reduces lung injury

ABSTRACTIn order to optimize the lung-protective potential of high-frequency oscillatory ventilation (HFOV), it is currently recommended to maximize oscillatory frequencies. However, very high frequencies may lead to insufficient CO2 elimination with severe respiratory acidosis. Arteriovenous extracorporeal lung assist (av-ECLA) allows near total CO2 removal, thereby allowing for maximization of the lung-protective potential of HFOV. The aim of this study was to determine the impact of HFOV and av-ECLA on lung inflammation and function compared to conventional lung-protective ventilation. In a porcine surfactant depletion model of lung injury, the authors randomly assigned 16 female pigs to conventional lung-protective ventilation and HFOV/ECLA. Both strategies were combined with an “open-lung” approach. Gas exchange and hemodynamic parameters were measured at intervals during the 24-hour study period. Postmortem, lung tissue was analyzed to determine histological damage and lung inflammation. The authors found that the combination of HFOV and av-ECLA (1) allows significant reductions in mean and peak airway pressures; and (2) reduces histological signs of lung inflammation in the basal regions of the lung. HFOV/av-ECLA reduces histological signs of lung inflammation compared to conventional lung-protective ventilation strategies. Thus, combination of HFOV and av-ECLA might be a further lung-protective tool if conventional ventilation strategies are failing.

Humidification during high-frequency oscillation ventilation is affected by ventilator circuit and ventilatory setting

High-frequency oscillation ventilation (HFOV) is an accepted ventilatory mode for acute respiratory failure in neonates. As conventional mechanical ventilation, inspiratory gas humidification is essential. However, humidification during HFOV has not been clarified. In this bench study, we evaluated humidification during HFOV in the open circumstance of ICU. Our hypothesis is that humidification during HFOV is affected by circuit design and ventilatory settings. We connected a ventilator with HFOV mode to a neonatal lung model that was placed in an infant incubator set at 37 degrees C. We set a heated humidifier (Fisher & Paykel) to obtain 37 degrees C at the chamber outlet and 40 degrees C at the distal temperature probe. We measured absolute humidity and temperature at the Y-piece using a rapid-response hygrometer. We evaluated two types of ventilator circuit: a circuit with inner heating wire and another with embedded heating element. In addition, we evaluated three lengths of the inspiratory limb, three stroke volumes, three frequencies, and three mean airway pressures. The circuit with embedded heating element provided significantly higher absolute humidity and temperature than one with inner heating wire. As an extended tube lacking a heating wire was shorter, absolute humidity and temperature became higher. In the circuit with inner heating wire, absolute humidity and temperature increased as stroke volume increased. Humidification during HFOV is affected by circuit design and ventilatory settings.

Effect of an intra-oral nasal dilation appliance on 3-D nasal airway morphology in adults

To determine the effects of a nasal dilation appliance on 3-D nasopharyngeal airway patency. The sample comprised 187 adults (98 males, 89 females) with a history of sleep-disordered breathing. Acoustic rhinometry readings were taken from all patients before and after the intra-oral placement of a nasal dilation appliance (OASYS). The mean left and right nasopharyngeal airways were reconstructed in 3-D, and the data from the right and left nostrils were subjected to principal components analysis (PCA) and finite-element scaling analysis (FESA). Comparing the pre- and post-treatment 3-D mean, left nasopharyngeal airways using PCA, the first two eigenvalues accounted for 96% of the total shape change, and statistical differences were found (p < 0.01). Similarly, for the right side, significant differences were detected between the mean pre- and post-treatment 3-D nasopharyngeal airways (p < 0.01) using PCA. Using FESA to quantify and localize changes after the placement of the nasal dilation appliance, the 3-D mean, normalized, left nasopharyngeal airway was found to be 14% wider in the anterior nasal valve region and 28% wider in the distal regions, while the 3-D mean, normalized, right nasopharyngeal airway was 13% wider in the anterior nasal valve region and 27% wider further distally. The use of an intra-oral nasal dilation appliance may be useful in the management of nasopharyngeal conditions, such as snoring, upper airway resistance syndrome, sleep-disordered breathing, and obstructive sleep apnea, especially in cases where nasal obstruction is demonstrable.

Der klinische Einsatz eines Schlafapnoescreeners in der Praxis

About 2-4% of adults suffer from obstructive sleep apnea (OSA), which is the most common sleep-related breathing disorder (SRBD). Repetitive obstructions of the upper airway mean that it is associated with hypertension and an elevated cardio- and cerebrovascular morbidity, which can be lowered by means of effective therapy. These patients cannot be treated correctly unless they are identified early in the course of the condition. Therefore, this study evaluated the use of the microMESAM screening device (known up to December 2005 as the "ApneaLink") in 61 patients in whom SRBD was suspected. The device proved reliable and practical in application.

High frequency oscillatory ventilation in burn patients with the acute respiratory distress syndrome

Background: High frequency oscillatory ventilation (HFOV) improves gas exchange while providing lung protective effects during the ventilation of patients with the acute respiratory distress syndrome (ARDS). The purpose of this study was to review our experience with HFOV in adult burn patients with oxygenation failure secondary to ARDS. Methods: Retrospective cohort review of all burn patients treated with HFOV at a regional adult burn center. Results: All values are reported as the mean± standard deviation (S.D.). HFOV was used on 28 occasions in 25 patients (age 44±16 years, %TBSA burns 40±15, and a 28% incidence of inhalation injury) who had severe oxygenation failure from ARDS (PaO 2/FiO 2 ratio 98±26, and oxygenation index (OI) (FiO 2×100×mean airway pressure/PaO 2) 27±10) following 4.8±4.4 days of conventional mechanical ventilation (CMV). After switching from CMV to HFOV, there were significant improvements in the PaO 2/FiO 2 ratio within 1 h and in the oxygenation index within 24 h. The duration of HFOV was 6.1±5.8 days. HFOV was continued during 26 surgeries for 14 patients where a mean of 18±9% TBSA burns were excised and closed. The only complications related to HFOV were three episodes of severe hypercapnia. In-hospital mortality was 32%. Conclusions: HFOV was safe, and was highly effective in correcting oxygenation failure associated with ARDS in burn patients, and can be successfully used as an intra-operative ventilation modality for burn patients.