Performance characteristics of high-frequency percussive ventilation under hyperbaric conditions.

Introduction: Safe administration of critical care hyperbaric medicine requires specialized equipment and advanced training. Equipment must be tested in order to evaluate function in the hyperbaric environment. High-frequency percussive ventilation (HFPV) has been used in intensive care settings effectively, but it has never been tested in a hyperbaric chamber. Methods: Following a modified U.S. Navy testing protocol used to evaluate hyperbaric ventilators, we evaluated an HFPV transport ventilator in a multiplace hyperbaric chamber at 1.0, 1.9, and 2.8 atmospheres absolute (ATA). We used a test lung with analytical software for data collection. The ventilator uses simultaneous cyclic pressure-controlled ventilation at a pulsatile flow rate (PFR)/oscillatory continuous positive airway pressure (oCPAP) ratio of 30/10 with a high-frequency oscillation percussive rate of 500 beats per minute. Inspiratory and expiratory times were maintained at two seconds throughout each breathing cycle. Results: During manned studies, the PFR/oCPAP ratios were 26/6, 22/7, and 22.5/8 at an airway resistance of 20cm H2O/L/second and 18/9, 15.2/8.5, and 13.6/7 at an airway resistance of 50 cm/H2O/L/second at 1, 1.9, and 2.8 ATA. The resulting release volumes were 800, 547, and 513 mL at airway resistance of 20 cm H2O/L/sec and 400, 253, and 180 mL at airway resistance of 50 cm/H2O/L/sec at 1, 1.9, and 2.8 ATA. Unmanned testing showed similar changes. The mean airway pressure (MAP) remained stable throughout all test conditions; theoretically, supporting adequate lung recruitment and gas exchange. A case where HFPV was used to treat a patient for CO poisoning was presented to illustrate that HFPV worked well under HBO2 conditions and no complications occurred during HBO2 treatment. Conclusion: The HFPV transport ventilator performed adequately under hyperbaric conditions and should be considered a viable option for hyperbaric critical care. This ventilator has atypical terminology and produces unique pulmonary physiology, thus requiring specialized training prior to use.

A Randomized Trial of Laryngeal Mask Airway in Neonatal Resuscitation.

BACKGROUND: Face-mask ventilation is the most common resuscitation method for birth asphyxia. Ventilation with a cuffless laryngeal mask airway (LMA) has potential advantages over face-mask ventilation during neonatal resuscitation in low-income countries, but whether the use of an LMA reduces mortality and morbidity among neonates with asphyxia is unknown. METHODS: In this phase 3, open-label, superiority trial in Uganda, we randomly assigned neonates who required positive-pressure ventilation to be treated by a midwife with an LMA or with face-mask ventilation. All the neonates had an estimated gestational age of at least 34 weeks, an estimated birth weight of at least 2000 g, or both. The primary outcome was a composite of death within 7 days or admission to the neonatal intensive care unit (NICU) with moderate-to-severe hypoxic-ischemic encephalopathy at day 1 to 5 during hospitalization. RESULTS: Complete follow-up data were available for 99.2% of the neonates. A primary outcome event occurred in 154 of 563 neonates (27.4%) in the LMA group and 144 of 591 (24.4%) in the face-mask group (adjusted relative risk, 1.16; 95% confidence interval [CI], 0.90 to 1.51; P = 0.26). Death within 7 days occurred in 21.7% of the neonates in the LMA group and 18.4% of those in the face-mask group (adjusted relative risk, 1.21; 95% CI, 0.90 to 1.63), and admission to the NICU with moderate-to-severe hypoxic-ischemic encephalopathy at day 1 to 5 during hospitalization occurred in 11.2% and 10.1%, respectively (adjusted relative risk, 1.27; 95% CI, 0.84 to 1.93). Findings were materially unchanged in a sensitivity analysis in which neonates with missing data were counted as having had a primary outcome event in the LMA group and as not having had such an event in the face-mask group. The frequency of predefined intervention-related adverse events was similar in the two groups. CONCLUSIONS: In neonates with asphyxia, the LMA was safe in the hands of midwives but was not superior to face-mask ventilation with respect to early neonatal death and moderate-to-severe hypoxic-ischemic encephalopathy. (Funded by the Research Council of Norway and the Center for Intervention Science in Maternal and Child Health; NeoSupra ClinicalTrials.gov number, NCT03133572.).

Positive End-Expiratory Pressure in Newborn Resuscitation Around Term: A Randomized Controlled Trial.

BACKGROUND: International guidelines for resuscitation recommend using positive end-expiratory pressure (PEEP) during ventilation of preterm newborns. Reliable PEEP-valves for self-inflating bags have been lacking, and effects of PEEP during resuscitation of term newborns are insufficiently studied. The objective was to determine if adding a new PEEP valve to the bag-mask during resuscitation of term and near-term newborns could improve heart rate response. METHODS: This randomized controlled trial was performed at Haydom Lutheran Hospital in Tanzania (September 2016 to June 2018). Helping Babies Breathe-trained midwives performed newborn resuscitation using self-inflating bags with or without a new, integrated PEEP valve. All live-born newborns who received bag-mask ventilation at birth were eligible. Heart rate response measured by ECG was the primary outcome, and clinical outcome and ventilation data were recorded. RESULTS: Among 417 included newborns (median birth weight 3200 g), 206 were ventilated without and 211 with PEEP. We found no difference in heart rate response. Median (interquartile range) measured PEEP in the PEEP group was 4.7 (2.0-5.6) millibar. The PEEP group received lower tidal volumes (4.9 [1.9-8.2] vs 6.3 [3.9-10.5] mL/kg; P = .02) and had borderline lower expired CO2 (2.9 [1.5-4.3] vs 3.3 [1.9-5.0] %; P = .05). Twenty four-hour mortality was 9% in both groups. CONCLUSIONS: We found no evidence for improved heart rate response during bag-mask ventilation with PEEP compared with no PEEP. The PEEP valve delivered a median PEEP within the intended range. The findings do not support routine use of PEEP during resuscitation of newborns around term.

Titration of extra-PEEP against intrinsic-PEEP in severe asthma by electrical impedance tomography: A case report and literature review.

RATIONALE: The use of extra-positive end-expiratory pressure (PEEP) at a level of 80% intrinsic-PEEP (iPEEP) to improve ventilation in severe asthma patients with control ventilation remains controversial. Electrical impedance tomography (EIT) may provide regional information for determining the optimal extra-PEEP to overcome gas trapping and distribution. Moreover, the experience of using EIT to determine extra-PEEP in severe asthma patients with controlled ventilation is limited. PATIENTS CONCERNS: A severe asthma patient had 12-cmH2O iPEEP using the end-expiratory airway occlusion method at Zero positive end-expiratory pressures (ZEEP). How to titrate the extra-PEEP to against iPEEP at bedside? DIAGNOSES AND INTERVENTIONS: An incremental PEEP titration was performed in the severe asthma patient with mechanical ventilation. An occult pendelluft phenomenon of the ventral and dorsal regions was found during the early and late expiration periods when the extra-PEEP was set to <6 cmH2O. If the extra-PEEP was elevated from 4 to 6 cmH2O, a decrease in the end-expiratory lung impedance (EELI) and a disappearance of the pendelluft phenomenon were observed during the PEEP titration. Moreover, there was broad disagreement as to the "best" extra-PEEP settings according to the various EIT parameters. The regional ventilation delay had the lowest extra-PEEP value (10 cmH2O), whereas the value was 12 cmH2O for the lung collapse/overdistension index and 14 cmH2O for global inhomogeneity. OUTCOMES: The extra-PEEP was set at 6 cmH2O, and the severe whistling sound was improved. The patient's condition further became better under the integrated therapy. LESSONS: A broad literature review shows that this was the 3rd case of using EIT to titrate an extra-PEEP to against PEEPi. Importantly, the visualization of occult pendelluft and possible air release during incremental PEEP titration was documented for the first time during incremental PEEP titration in patients with severe asthma. Examining the presence of the occult pendelluft phenomenon and changes in the EELI by EIT might be an alternative means for determining an individual's extra-PEEP.

Improved oxygenation during standing performance of deep breathing exercises with positive expiratory pressure after cardiac surgery: A randomized controlled trial.

OBJECTIVE: Breathing exercises after cardiac surgery are often performed in a sitting position. It is unknown whether oxygenation would be better in the standing position. The aim of this study was to evaluate oxygenation and subjective breathing ability during sitting vs standing performance of deep breathing exercises on the second day after cardiac surgery. METHODS: Patients undergoing coronary artery bypass grafting (n = 189) were randomized to sitting (controls) or standing. Both groups performed 3 × 10 deep breaths with a positive expiratory pressure device. Peripheral oxygen saturation was measured before, directly after, and 15 min after the intervention. Subjective breathing ability, blood pressure, heart rate, and pain were assessed. RESULTS: Oxygenation improved significantly in the standing group compared with controls directly after the breathing exercises (p < 0.001) and after 15 min rest (p = 0.027). The standing group reported better deep breathing ability compared with controls (p = 0.004). A slightly increased heart rate was found in the standing group (p = 0.047). CONCLUSION: After cardiac surgery, breathing exercises with positive expiratory pressure, performed in a standing position, significantly improved oxygenation and subjective breathing ability compared with sitting performance. Performance of breathing exercises in the standing position is feasible and could be a valuable treatment for patients with postoperative hypoxaemia.

Efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation in patients undergoing off-pump coronary artery bypass grafting.

BACKGROUND: Postoperative complications after cardiac surgery increase mortality. This study aimed to evaluate the efficacy of cardiopulmonary rehabilitation with adaptive servo-ventilation (ASV) in patients undergoing off-pump coronary artery bypass grafting (OPCAB). METHODS AND RESULTS: A total of 66 patients undergoing OPCAB were enrolled and divided into 2 groups according to the use of ASV (ASV group, 30 patients; non-ASV group, 36 patients). During the perioperative period, all patients undertook cardiopulmonary rehabilitation. ASV was used from postoperative day (POD) 1 to POD5. Hemodynamics showed a different pattern in the 2 groups. Blood pressure (BP) on POD6 in the ASV group was significantly lower than that in the non-ASV group (systolic BP, 112.9±12.6 vs. 126.2±15.8 mmHg, P=0.0006; diastolic BP, 62.3±9.1 vs. 67.6±9.3 mmHg, P=0.0277). The incidence of postoperative atrial fibrillation (POAF) was lower in the ASV group than in the non-ASV group (10% vs. 33%, P=0.0377). The duration of oxygen inhalation in the ASV group was significantly shorter than that in the non-ASV group (5.1±2.2 vs. 7.6±6.0 days, P=0.0238). The duration of postoperative hospitalization was significantly shorter in the ASV group than in the non-ASV group (23.5±6.6 vs. 29.0±13.1 days, P=0.0392). CONCLUSIONS: Cardiopulmonary rehabilitation with ASV after OPCAB reduces both POAF occurrence and the duration of hospitalization.

Assessing self-efficacy of frontline providers to perform newborn resuscitation in a low-resource setting.

OBJECTIVES: Newborn deaths comprise an alarming proportion of under-five mortality globally. In this retrospective cohort study, we investigated the effectiveness of focused newborn resuscitation training and delivery of a positive-pressure device in a rural midwife population in a low-resource setting. The present research attempts to better understand the extent to which knowledge and self-efficacy contribute to resuscitation attempts by birth attendants in practice. METHODS: A one-year retrospective cohort analysis was undertaken in Aceh, Indonesia of two groups of community-based midwives, one having received formal training and a positive-pressure resuscitative device and the other receiving usual educational resources and management. A path analysis was undertaken to evaluate relative determinants of actual resuscitation attempts. RESULTS: 348 community-based midwives participated in the evaluation and had attended 3116 births during the preceding year. Path analysis indicated that formal training in resuscitation and delivery of a positive-pressure device were significantly related to both increased knowledge (ß=0.55, p=0.001) and increased self-efficacy (ß=0.52, p=0.001) in performing neonatal resuscitations with a positive-pressure device. However, training impacted actual resuscitation attempts only indirectly through a relationship with self-efficacy and with knowledge. Combined across groups, self-efficacy was significantly associated with positive pressure ventilation attempts (ß=0.26, p<0.01) whereas knowledge was not (ß=-0.05, p=0.39). CONCLUSION: Although, to date, evaluations of newborn resuscitation programs have primarily focused on training and has reported process indicators, these results indicate that in order to improve intrapartum-related hypoxic events ("birth asphyxia"), increased emphasis should be placed on participant self-efficacy and mastery of newborn resuscitation.

A review of EPAP nasal device therapy for obstructive sleep apnea syndrome.

BACKGROUND: Expiratory positive airway pressure (EPAP) nasal devices provide a new therapeutic option for obstructive sleep apnea (OSA). METHODS: Here, we review the literature about treatment of OSA with EPAP, which has been shown to reduce the apnea/hypopnea index (AHI) and daytime sleepiness. RESULTS: Patients generally prefer EPAP to continuous positive airway pressure (CPAP), and there are no serious adverse effects from its use. Although CPAP more effectively improves sleep apnea, a recent study showed similar outcomes in symptom improvement using EPAP. Patients with mild to moderate OSA who do not tolerate CPAP are appropriate candidates for EPAP. However, there are few well-designed clinical trials that evaluate efficacy. CONCLUSIONS: More studies are needed to assess the efficacy of and compliance with EPAP nasal devices, to define which patients will benefit from EPAP therapy, and to compare EPAP to other alternative OSA therapies.

Analysis of acoustic frequency and wave amplitude generated by the Oscillatory Thoracic Thixotropic Device (Diottix(r)) in human chest / Análisis de la frecuencia acústica y amplitud de las ondas sonoras generadas por el Dispositivo Oscilatorio Torácico Tixotrópico (Diottix(r)) en el tórax humano / Análise da frequência acústica e amplitude das ondas sonoras geradas pelo Dispositivo Oscilatório Torácico Tixotrópico (Diottix(r)) no tórax humano

Diottix(r) was calibrated at 25 Hz to achieve the frequency indicated in literature as being effective to mobilize the airways secretions. However, the amplitude and frequency of the waves generated by the equipment in different regions of the chest still need to be investigated. The objective of this study was to analyze the frequency and amplitude of waves generated by Diottix(r) in chests of healthy subjects. Diottix(r) was used in the anterior and posterior regions of the chest. The mechanical waves were captured using stethoscopes connected to electret microphones, which were connected to a digital oscilloscope. Frequency and amplitude data were recorded by the stethoscope, positioned in six points in the anterior region and six in the posterior region of the chest, following the positions commonly used in pulmonary auscultation. Signals were recorded and transferred to a computer with software for their analysis. The frequency of waves did not present a significant change (from 24.9 to 26.4 Hz). The wave amplitude in the anterior versus the posterior region in each area of the lung, the upper, middle and lower, had differences. Diottix(r) produces frequencies in the chest according to the calibrated; thus, it can be a complementary resource to bronchial hygiene maneuvers. The amplitudes of waves seem to be affected by other structures like bone parts and heart.

Diottix(r) fue calibrado en 25 Hz para alcanzar la frecuencia indicada en la literatura como eficaz para movilizar secreciones de las vías aéreas. La amplitud y frecuencia de ondas generadas por el equipamiento en las diferentes regiones del tórax aun necesitan de más investigaciones. El objetivo de eso estudio fue analizar la frecuencia y amplitud de ondas generadas por el Diottix(r) en el tórax de sujetos saludables. La aplicación del Diottix(r) fue realizada en las regiones anterior y posterior del tórax. Las ondas mecánicas fueron captadas utilizándose estetoscopios ligados a micrófonos de electret, los cuales estaban ligados a uno osciloscopio digital. Los datos de frecuencia y amplitud fueron captados por lo estetoscopio posicionado en seis puntos en la región anterior y seis en la posterior del tórax, siguiendo las posiciones comúnmente utilizadas en la ausculta pulmonar. Los sígnales fueron registrados y transferidos para una computadora a través de un programa para su análisis de datos. La frecuencia de ondas no presentó variación significativa (del 24,9 al 26,4 Hz). La amplitud de onda en la región anterior versus posterior en cada segmento del pulmón, tercio superior, medio e inferior, presentó diferencia. Lo Diottix(r) produce frecuencias en el tórax según el calibrado. Por lo tanto, puede ser uno recurso complementar a las manobras de higiene de los bronquios. Las amplitudes de ondas parecen ser afectadas por otras estructuras, las cuales incluyen partes óseas y el corazón.

O Diottix(r) foi calibrado a 25 Hz para atingir a frequência indicada na literatura como eficaz a fim de mobilizar secreções de vias aéreas. A amplitude e a frequência das ondas geradas pelo equipamento nas diferentes regiões do tórax ainda precisam ser investigadas. O objetivo de estudo foi analisar a frequência e a amplitude das ondas geradas pelo Diottix(r) no tórax de indivíduos saudáveis. A aplicação do Diottix(r) foi realizada nas regiões anterior e posterior do tórax. As ondas mecânicas foram captadas utilizando estetoscópios conectados a microfones de eletreto, os quais estavam ligados a um osciloscópio digital. Os dados de frequência e amplitude foram captados pelo estetoscópio, posicionado em seis pontos na região anterior e seis na posterior do tórax, seguindo as posições comumente utilizadas na ausculta pulmonar. Os sinais foram registrados e transferidos para um computador por meio de um software para análise deles. A frequência das ondas não apresentou variação significativa (24,9 a 26,4 Hz). A amplitude de onda na região anterior versus posterior em cada segmento do pulmão, terço superior, médio e inferior, apresentou diferença. O Diottix(r) produz frequências no tórax de acordo com o calibrado; desta forma, pode ser um recurso complementar às manobras de higiene brônquica. As amplitudes de ondas parecem ser afetadas por outras estruturas, que incluem as partes ósseas e o coração.

Pilot study of nasal expiratory positive airway pressure devices for the treatment of childhood obstructive sleep apnea syndrome.

STUDY OBJECTIVES: Alternative therapies for childhood obstructive sleep apnea syndrome (OSAS) are needed as OSAS may persist despite adenotonsillectomy, and continuous positive airway pressure (CPAP) adherence is low. Nasal expiratory positive airway pressure (NEPAP) devices have not been studied in children. We hypothesized that NEPAP would result in polysomnographic improvement. Further, we aimed to determine NEPAP adherence, effects on sleepiness, behavior, and quality of life. METHODS: A randomized, double-blind, placebo-controlled, crossover pilot study was performed. CPAP candidates, 8-16 years old, underwent NEPAP and placebo polysomnograms. Subjects with ≥ 50% reduction in the apnea hypopnea index (AHI) from placebo to NEPAP night or AHI < 5/h on NEPAP night wore NEPAP at home for 30 days. Adherence was assessed by daily phone calls/emails and collecting used devices. RESULTS: Fourteen subjects (age 13.4 ± 1.9 years, BMI z-scores 2.2 ± 1 [mean ± SD]) were studied. There was significant improvement in the obstructive apnea index with NEPAP vs. placebo: 0.6 (0-21.1)/h vs. 4.2 (0-41.9)/h (median [range], p = 0.010) and trends for improvement in other polysomnographic parameters. However, responses were variable, with 3 subjects not improving and 2 worsening. Older children and those with less hypercapnia had a better response. Eight subjects were sent home with devices; one was lost to follow-up, and adherence in the remainder was 83% of nights; these subjects had a significant improvement in sleepiness and quality of life. CONCLUSIONS: NEPAP devices are a potential alternative therapy for OSAS in a small subset of children. Due to variability in individual responses, efficacy of NEPAP should be evaluated with polysomnography. CLINICAL TRIAL REGISTRATION: www.clinicaltrials.gov, identifier: NCT01768065.

Essentials of airway management, oxygenation, and ventilation: part 1: basic equipment and devices.

Offices and outpatient dental facilities must be properly equipped with devices for airway management, oxygenation, and ventilation. Optimizing patient safety using crisis resource management (CRM) involves the entire dental office team being familiar with airway rescue equipment. Basic equipment for oxygenation, ventilation, and airway management is mandated in the majority of US dental offices per state regulations. The immediate availability of this equipment is especially important during the administration of sedation and anesthesia as well as the treatment of medical urgencies/emergencies. This article reviews basic equipment and devices essential in any dental practice whether providing local anesthesia alone or in combination with procedural sedation. Part 2 of this series will address advanced airway devices, including supraglottic airways and armamentarium for tracheal intubation and invasive airway procedures.

MRI under hyperbaric air and oxygen: effects on local magnetic field and relaxation times.

PURPOSE: Hyperbaric oxygen therapy has shown efficacies in the treatment of a number of diseases. The goal of this study was to develop a rodent hyperbaric chamber for MRI studies and to investigate the effects of hyperbaric air and hyperbaric oxygen on local magnetic field (B0 ) and MRI relaxation parameters in the rat brain. METHODS: A hyperbaric chamber, constructed to fit inside an animal MRI scanner, was pressurized with air to four atmospheres, while oxygen was delivered locally via nose cone. B0 , T2 , T2 *, and T1 maps in the rat brain were evaluated under normobaric air, hyperbaric air, and hyperbaric oxygen at 7T. RESULTS: Under hyperbaric oxygen, images exhibited artifacts and temporal instability, attributable to fluctuating oxygen concentration from air and oxygen mixing near the imaging region. Physically shielding the imaging region from fluctuating oxygen concentration resolved the problems. With increasing oxygen at hyperbaric pressure, B0 was shifted downfield with increased inhomogeneity near the ear canals and nose. Brain T2 and T2 * were lengthened, and T1 was shortened. CONCLUSION: This study establishes the means to perform MRI on rodents under hyperbaric conditions. Hyperbaric air and hyperbaric oxygen have significant effects on B0 and tissue relaxation parameters compared with normobaric air.

Deep breathing exercises with positive expiratory pressure at a higher rate improve oxygenation in the early period after cardiac surgery--a randomised controlled trial.

OBJECTIVE: In addition to early mobilisation, a variety of breathing exercises are used to prevent postoperative pulmonary complications after cardiac surgery. The optimal duration of the treatment is not well evaluated. The aim of this study was to determine the effect of 30 versus 10 deep breaths hourly, while awake, with positive expiratory pressure on oxygenation and pulmonary function the first days after cardiac surgery. METHODS: A total of 181 patients, undergoing cardiac surgery, were randomised into a treatment group, performing 30 deep breaths hourly the first postoperative days, or into a control group performing 10 deep breaths hourly. The main outcome measurement arterial blood gases and the secondary outcome pulmonary function, evaluated with spirometry, were determined on the second postoperative day. RESULTS: Preoperatively, both study groups were similar in terms of age, SpO(2), forced expiratory volume in 1s and New York Heart Association classification. On the second postoperative day, arterial oxygen tension (PaO(2)) was 8.9 ± 1.7 kPa in the treatment group and 8.1 ± 1.4 kPa in the control group (p = 0.004). Arterial oxygen saturation (SaO(2)) was 92.7 ± 3.7% in the treatment group and 91.1 ± 3.8% in the control group (p = 0.016). There were no differences in measured lung function between the groups or in compliance to the breathing exercises. Compliance was 65% of possible breathing sessions. CONCLUSIONS: A significantly increased oxygenation was found in patients performing 30 deep breaths the first two postoperative days compared with control patients performing 10 deep breaths hourly. These results support the implementation of a higher rate of deep breathing exercises in the initial phase after cardiac surgery.

A comparison of the Acapella and a threshold inspiratory muscle trainer for sputum clearance in bronchiectasis-A pilot study.

BACKGROUND: Inspiratory muscle training is used to specifically strengthen the respiratory muscles. Controversy exists regarding the use of inspiratory muscle training as a method of facilitating airways clearance. Acapella is already known to be effective in airway clearance. OBJECTIVE: The objective of the study was to compare the effects of the Acapella and a threshold inspiratory muscle trainer as a method of airway clearance in subjects with bronchiectasis and to determine patient preference between the two techniques. METHODS: Thirty patients (10 males, 20 females) mean age of 50.67+/-6.37 (mean+/-SD) with a history of expectoration of more than 30 ml sputum per day were recruited. The sequence of therapy was allocated by block randomization. Assessment and familiarization session was performed on day 1. Treatments employing the Acapella and inspiratory muscle trainer were done on days 2 and 3. Treatment order and allocation was determined by block randomization. Sputum volume was measured during and 2 hours after the treatment and patient treatment preference was recorded. RESULTS: A statistically significant difference was found in the sputum volume expectorated after treatment with the Acapella (7.16+/-1.12 ml) compared with the threshold inspiratory muscle trainer (6.46+/-1.08 ml). Patients preferred Acapella in terms of usefulness of clearing secretions. CONCLUSION: The present study demonstrated increased sputum clearance following the use of the Acapella when compared to the threshold inspiratory muscle trainer. In addition, the Acapella was preferred by patients who judged that it was more useful in clearing secretions.

Continuous positive airway pressure therapy: new generations.

Continuous positive airway pressure (CPAP) is the treatment of choice for obstructive sleep apnoea syndrome (OSAS). However, CPAP is not tolerated by all patients with OSAS and alternative modes of pressure delivery have been developed to overcome pressure intolerance, thereby improving patient comfort and adherence. Auto-adjustable positive airway pressure (APAP) devices may be utilised for the long-term management of OSAS and may also assist in the initial diagnosis of OSAS and titration of conventional CPAP therapy. Newer modalities such as C-Flex and A-Flex also show promise as treatment options in the future. However, the evidence supporting the use of these alternative modalities remains scant, in particular with regard to long-term cardiovascular outcomes. In addition, not all APAP devices use the same technological algorithms and data supporting individual APAP devices cannot be extrapolated to support all. Further studies are required to validate the roles of APAP, C-Flex and A-Flex. In the interim, standard CPAP therapy should continue as the mainstay of OSAS management.

The self-inflating resuscitation bag delivers high oxygen concentrations when used without a reservoir: implications for neonatal resuscitation.

OBJECTIVE: To measure the delivered fractional oxygen concentration (F(DO(2))) from preterm-size Laerdal silicone resuscitators (PLSR) without a reservoir. BACKGROUND: The North American Neonatal Resuscitation Program manual states that self-inflating bags without a reservoir deliver approximately 40% oxygen, differing from the PLSR manufacturer's specifications. METHODS: A neonatal test lung was manually ventilated using PLSRs without a reservoir. A 50 psi 100% oxygen source and an oxygen flow meter were used to provide desired oxygen inlet flows. F(DO(2)) was measured using 3 different PLSRs after 4 min of manual ventilation of a neonatal test lung, at differing inspired tidal volumes (5 mL or 20 mL), respiratory rates (40 breaths/min or 60 breaths/min), and oxygen inlet flows (1 to 4, 5, and 10 L/min). RESULTS: In all tests using 5 or 10 L/min, exceeded 0.95. The lowest F(DO(2)) was 0.59, at 1 L/min. CONCLUSIONS: The F(DO(2)) measured during this study did not differ from PLSR specifications. The F(DO(2)) did, however, differ from information contained in the North American Neonatal Resuscitation Program manual regarding use of a self-inflating bag without a reservoir. Care should be taken when selecting a self-inflating resuscitation device to provide blended air and oxygen, as high concentrations of oxygen may be delivered by these devices even when the reservoir is removed. American and Canadian recommendations for the provision of supplemental oxygen with self-inflating bags require reevaluation.

Adaptation of the Threshold IMT with double spring load allows higher inspiratory pressure for muscle training.

PURPOSE: We aimed to evaluate the functionality of an adapted inspiratory muscle training device designed to allow pressures higher than 41 cmH(2)O that can be precisely controlled. The adaptation was made in a commercially available Threshold IMT device, and the opening pressures and linearity of load were evaluated in an experimental setting. METHODS: The original IMT Threshold device was modified by inserting a second spring load juxtaposed to the original spring and then the modified device was coupled to a system designed to assess the range of opening pressures. Linear regression was used to test the correlation between the visual pressure scale of the original device and the opening pressure load obtained from the adapted device. RESULTS: For the modified device, we found a range of load from 13.9 +/- 0.7 to 85.6 +/- 0.7 cmH(2)O. Linear regression analysis of our data found an excellent relation between the modified device's opening pressure and the preset opening pressure marked on the visual scale in the original device, y = -1.275 + 2.08x, r(2) = 0.99 and P = 0.0001. CONCLUSION: The Threshold IMT adaptation proposed here is simple, affordable, precise, safe and allows for a high degree of reproducibility. It also achieves pressures higher than 41 cmH(2)O that can be used when training inspiratory muscles.

Generador de flujo con presión binivelada (BiPAP) a través de traqueostomía / Flow generator with double level pressure (BiPAP) through tracheostomy

Background: The Chilean Program of Noninvasive Home Ventilation started using flow generating equipment with differential pressure at 2 levels (BiPAP) through tracheostomies for prolonged mechanical ventilation (PMV). Objective: Describe the experience of this ventilatory support, reporting selection criteria, procedure and technological requirements. Method: Descriptive-transversal study that includes 20 patients treated at Hospital Josefina Martinez, other pediatric hospitals and at home, for 12 months since June 2006. The clinical features, ventilation support, technical characteristics, follow-up and complications were reported. Results: The mean age was 3.5 years-old (range 3 months - 17 years). The duration of PMV ranged between 1 month to 5 years. Six patients (30 percent) are at home and 14 (70 percent) are hospitalized. In 14 patients (70 percent), the need of PMV was due to neuromuscular diseases. There was no mortality related to the use of Bipap through tracheostomy; only 4 patients had minor complications. Conclusions: This report suggests that the use of BiPAP through tracheostomy in patients with selection criteria is an applicable PVM method. However, comparative systematic trials are necessary to define costs, benefits and risks of this type of ventilation.

Introducción: El Programa Chileno de Ventilación No Invasiva en domicilio (AVNI) extendió su cobertura utilizando generadores de flujo con presión bi-nivelada (BiPAP) en niños con ventilación mecánica prolongada (VMP) y traqueostomía (TQT). Objetivo: Reportar la experiencia de esta estrategia describiendo criterios de selección, modalidades de uso y tecnologías complementarias. Pacientes y Métodos: Estudio descriptivo, transversal y prospectivo durante un año desde Junio 2006, en 20 pacientes manejados en el Hospital Josefina Martínez, otros centros de la red asistencial del Ministerio de Salud y en domicilio. Se registraron las características clínicas, modos ventilatorios, evolución y complicaciones. Resultados: La mediana de edad fue de 3,5 años (rango 3 meses a 17 a±os). La duración de la VMP fue lm a 5a, 6 pacientes (30 por ciento) se encuentran en domicilio y 14 (70 por ciento) hospitalizados. La principal causa para VMP fue enfermedad neuromuscular (14, 70 por ciento). No hubo mortalidad y 4 pacientes tuvieron complicaciones menores. Conclusión: El BiPAP a través de TQT, usado con criterios estrictos de selección, es un método de VMP que puede ser factible. Se requieren estudios comparativos para definir costos, beneficios y riesgos de estos equipos comparándolos con ventiladores licenciados para soporte vital.

Assessing the effectiveness of two round neonatal resuscitation masks: study 1.

BACKGROUND: Positive pressure ventilation (PPV) via a face mask is an important skill taught using manikins. There have been few attempts to assess the effectiveness of different face mask designs. AIM: To determine whether leak at the face mask during simulated neonatal resuscitation differed between a new round mask design and the current most widely used model. METHOD: 50 participants gave PPV to a modified manikin designed to measure leak at the face mask. Leak was calculated from the difference between the inspired and expired tidal volumes. RESULTS: Mask leak varied widely with no significant difference between devices; mean (SD) percentage leak for the Laerdal round mask was 55% (31) and with the Fisher & Paykel mask it was 57% (25). CONCLUSION: We compared a new neonatal face mask with an established design and found no difference in leak. On average the mask leak was >50% irrespective of operator experience or technique.

Improved techniques reduce face mask leak during simulated neonatal resuscitation: study 2.

BACKGROUND: Techniques of positioning and holding neonatal face masks vary. Studies have shown that leak at the face mask is common and often substantial irrespective of operator experience. AIMS: (1) To identify a technique for face mask placement and hold which will minimise mask leak. (2) To investigate the effect of written instruction and demonstration of the identified technique on mask leak for two round face masks. METHOD: Three experienced neonatologists compared methods of placing and holding face masks to minimise the leak for Fisher & Paykel 60 mm and Laerdal size 0/1 masks. 50 clinical staff gave positive pressure ventilation to a modified manikin designed to measure leak at the face mask. They were provided with written instructions on how to position and hold each mask and then received a demonstration. Face mask leak was measured after each teaching intervention. RESULTS: A technique of positioning and holding the face masks was identified which minimised leak. The mean (SD) mask leaks before instruction, after instruction and after demonstration were 55% (31), 49% (30), 33% (26) for the Laerdal mask and 57% (25), 47% (28), 32% (30) for the Fisher & Paykel mask. There was no significant difference in mask leak between the two masks. Written instruction alone reduced leak by 8.8% (CI 1.4% to 16.2%) for either mask; when combined with a demonstration mask leak was reduced by 24.1% (CI 16.4% to 31.8%). CONCLUSION: Written instruction and demonstration of the identified optimal technique resulted in significantly reduced face mask leak.