The Intermittent Abdominal Pressure Ventilator as an Alternative Modality of Noninvasive Ventilatory Support: A Narrative Review.

ABSTRACT: Noninvasive ventilation has become the initial treatment for symptomatic ventilatory pump failure but, when used at ventilatory support settings, can be an alternative to tracheostomy mechanical ventilation. The intermittent abdominal pressure ventilator, a corset with an internal air sack inflated by a ventilator, allows to increase tidal volumes through the raising of the diaphragm and its consequent passive descent. It has been used for daytime support for more than 70 yrs, but its knowledge among clinicians is scarce. A narrative review was performed by searching PubMed, Medline, and the Cochrane Database of Systematic Reviews using the terms "IAPV" or "pneumobelt." One hundred forty patients were cited using the intermittent abdominal pressure ventilator from 1946 until it went off the market in the 1970s, although many continued to use it. There was only one publication on its use from 2003 to 2017, but three publications from 2017 through 2021. It has been used for full diurnal ventilatory support by some patients for more than 50 yrs and has even been used throughout the labor of a mother with no ventilator-free breathing ability. The intermittent abdominal pressure ventilator is a ventilatory support alternative for patients with ventilatory pump failure. It can be effective and well tolerated and maintain quality of life without facial interfaces. More widespread application is warranted.

Flow-synchronized NIPPV with double-inspiratory loop cannula: An in vitro study.

BACKGROUND: Although short binasal prongs (SBP) are the most common interface for noninvasive ventilation, the "double-inspiratory loop cannulas" (DILC) have recently been introduced into many neonatal intensive care units. DILC show advantages over SBP, including reduced nasal trauma and increased comfort. However, their higher intrinsic resistance may compromise ventilation. Our aim was to test a new, low resistance DILC interface. METHODS: A test lung was programmed to simulate preterm neonates (500-2000 g BW) with moderate-to-severe respiratory distress syndrome. The artificial nose was designed to keep prongs-to-nares leaks to around 30%. Giulia® ventilator (GINEVRI srl) was used to provide nasal continuous positive airway pressure (NCPAP) and flow synchronized nasal intermittent positive pressure ventilation (NIPPV). NCPAP was set at 4-10 cmH2 O and synchronized-NIPPV (SNIPPV) at peak inspiratory pressure, 15-20-25 cmH2 O; inspiratory time, 0.3-0.5 s; and positive end-expiratory pressure, 5-8 cmH2 O. Four sizes of Sync-flow Cannula® (GINEVRI srl) were tested. The Sync-flow Cannula® was compared with Neotech RAM® cannula and Ginevri SBP®. The outcome measures were the flow/pressure relationship through the four Sync-flow Cannula® sizes, the difference in resistance, the drop in ventilator-alveoli pressure measured by the test lung and the system response time during flow-SNIPPV. RESULTS: The smaller DILC sizes had the lowest flow-pressure ratio. The resistance of the RAM® cannula was significantly higher compared to the other interfaces (p < .001). With 30% leaks, there was a 4-38% ventilator-alveoli drop in pressure, depending on interface size. The system response time was excellent (~65-70 ms). CONCLUSIONS: With about 30% leaks, the Sync-flow Cannula® interfaces result in good pressure transmission and give optimal performance for flow-SNIPPV. Clinical studies are needed to confirm the clinical relevance of these data.

ResUHUrge: A Low Cost and Fully Functional Ventilator Indicated for Application in COVID-19 Patients.

Although the cure for the SARS-CoV-2 virus (COVID-19) will come in the form of pharmaceutical solutions and/or a vaccine, one of the only ways to face it at present is to guarantee the best quality of health for patients, so that they can overcome the disease on their own. Therefore, and considering that COVID-19 generally causes damage to the respiratory system (in the form of lung infection), it is essential to ensure the best pulmonary ventilation for the patient. However, depending on the severity of the disease and the health condition of the patient, the situation can become critical when the patient has respiratory distress or becomes unable to breathe on his/her own. In that case, the ventilator becomes the lifeline of the patient. This device must keep patients stable until, on their own or with the help of medications, they manage to overcome the lung infection. However, with thousands or hundreds of thousands of infected patients, no country has enough ventilators. If this situation has become critical in the Global North, it has turned disastrous in developing countries, where ventilators are even more scarce. This article shows the race against time of a multidisciplinary research team at the University of Huelva, UHU, southwest of Spain, to develop an inexpensive, multifunctional, and easy-to-manufacture ventilator, which has been named ResUHUrge. The device meets all medical requirements and is developed with open-source hardware and software.

Effect of pressure rise time on ventilator parameters and gas exchange during neonatal ventilation.

BACKGROUND: Pressure rise time (PRT), also known as slope time to the peak inflating pressure can be set on some modern neonatal ventilators. On other ventilators, PRT is determined by the set circuit flow. Changing slope time can affect mean airway pressure (MAP), oxygenation, and carbon dioxide elimination. Our aim was to investigate the effect of PRT on ventilator parameters and gas exchange during volume-guaranteed ventilation. METHODS: In a crossover study, 12 infants weighing greater than 2 kg were ventilated using a Dräger Babylog VN500 ventilator with synchronized intermittent positive pressure ventilation with volume guarantee (SIPPV-VG) and pressure support ventilation with volume guarantee (PSV-VG). During both modes PRTs between 0.08 and 0.40 seconds were used in 15-minute epochs. Data from the ventilator and patient monitors were downloaded with 1- and 100-Hz sampling rate and analyzed using the Python computer language. RESULTS: During PSV-VG, longer PRTs were associated with longer inspiratory time (P < .0001) and with lower peak inflating pressure (PIP; P = .003), but the MAP was similar. During SIPPV-VG the PIP was not significantly different; however, MAP was lower with longer PRT (P = .001). With a short PRT (0.08 seconds), the PIP was higher during PSV-VG than during SIPPV-VG (19.8 vs 16.5 mbar; P = .042). There were no significant differences in tidal volume delivery, respiratory rate, minute volume, oxygen saturations, or end-tidal CO2 with different PRTs in either mode. CONCLUSIONS: During SIPPV-VG or PSV-VG, using short or long PRTs affects some ventilation parameters but does not significantly change oxygenation or carbon dioxide elimination.

Effect of sustained inflations and intermittent positive pressure ventilation on bronchopulmonary dysplasia or death among neonatal: A protocol for systematic review.

BACKGROUND: Sustained Inflations (SI) and Intermittent Positive Pressure Ventilation (IPPV) are two interventions to prevent Bronchopulmonary dysplasia (BPD). The aim of this study is to assess the effect of these two interventions. METHODS: The databases of PubMed, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) will be comprehensively searched from inception to September 2019. All RCTs and quasi-RCTs which compare the efficacy of SI vs IPPV among preterm infants are eligible. We will assess the methodological quality using the Cochrane Handbook version 5.1.0. A meta-analysis will be performed using RevMan 5.3 software and the results will be presented using risk ratios (RRs) and 95% confidence intervals (CIs). CONCLUSIONS: This study will provide strong evidence for assessing the effect of SI and IPPV on BPD or death among preterm infants. PROSPERO REGISTRATION NUMBER: CRD42019135816.

Randomized trial of mask or prongs for nasal intermittent mandatory ventilation in term infants with transient tachypnea of the newborn.

BACKGROUND: The aim of this study was to compare nasal masks (NM) with binasal prongs (NP) for applying nasal intermittent mandatory ventilation (NIMV) by assessing the duration of respiratory distress, rate of intubation, and nasal trauma in term infants with transient tachypnea of the newborn (TTN). METHODS: Infants with a gestational age ≥37 weeks and birthweight ≥2,000 g who had NIMV administered for TTN were enrolled. We randomly allocated 80 neonates to the NM (n = 40) or NP (n = 40) group. Duration of respiratory distress was the primary outcome of this study. RESULTS: There were no statistically significant differences between the groups for the duration of tachypnea and NIMV (P = 0.94 and P = 0.13, respectively). No significant differences were observed between the two groups in terms of duration of oxygen supplementation and length of hospitalization (P = 0.72 and P = 0.70, respectively). The incidence of any grade of trauma and moderate trauma (grade II) was significantly higher in the NP group than in the NM group (P = 0.004 and P = 0.04, respectively). The rate of NIMV failure and other complications, including pneumothorax, pneumonia and feeding intolerance, was not significantly different in the groups. CONCLUSIONS: In term infants with TTN, delivering NIMV using NP in comparison to using NM appears to be similar with regard to the duration of respiratory distress and preventing intubation. However, the use of NP involves a greater risk of trauma than that of NM.

Noninvasive Ventilation in the Delivery Room for the Preterm Infant.

A decade ago, preterm infants were prophylactically intubated and mechanically ventilated starting in the delivery room; however, now the shift is toward maintaining even the smallest of neonates on noninvasive respiratory support. The resuscitation of very low gestational age neonates continues to push the boundaries of neonatal care, as the events that transpire during the golden minutes right after birth prove ever more important for determining long-term neurodevelopmental outcomes. Continuous positive airway pressure (CPAP) remains the most important mode of noninvasive respiratory support for the preterm infant to establish and maintain functional residual capacity and decrease ventilation/perfusion mismatch. However, the majority of extremely low gestational age infants require face mask positive pressure ventilation during initial stabilization before receiving CPAP. Effectiveness of face mask positive pressure ventilation depends on the ability to detect and overcome mask leak and airway obstruction. In this review, the current evidence on devices and techniques of noninvasive ventilation in the delivery room are discussed.

A Mechanical Intermittent Abdominal Pressure Ventilator.

Pneumatically driven intermittent abdominal pressure ventilators were a popular means of daytime ventilatory support until the late 1960s paradigm shift to invasive (tracheostomy) mechanical ventilation. However, although many patients still use intermittent abdominal pressure ventilators, currently available turbine-driven portable home care ventilators are not powerful enough to always successfully operate them. We describe a new mechanically driven intermittent abdominal pressure ventilator operated by a 1-pound motor that provided a depth of abdominal compression of almost 2 in in 1.05 to 1.13 secs to normalize alveolar ventilation for a 72-yr-old postpolio survivor. It increased her autonomous 200- to 320-ml tidal volumes by greater than 300 ml to normalize her respiratory rate, relieve her dyspnea, and maintain normal oxyhemoglobin saturation levels throughout daytime hours for a 9-mo period of continuous ventilatory support.

A Randomized Controlled Trial of a Barrier Dressing to Reduce Nasal Injury in Preterm Infants Receiving Binasal Noninvasive Respiratory Support.

OBJECTIVE: To determine whether the use of a hydrocolloid nasal barrier dressing during binasal continuous positive airway pressure (CPAP) therapy, compared with no barrier dressing, reduces the rate of nasal injury in very preterm and/or very low birth weight infants. STUDY DESIGN: A single-center randomized controlled trial conducted in the neonatal intensive care unit at The Royal Women's Hospital, Melbourne. Eligible infants were born <30 weeks of gestation and/or with birth weight <1250 g, and had received ≥4 hours, but <48 hours, of CPAP. Infants were randomly allocated to receive either a hydrocolloid nasal barrier dressing during CPAP (barrier group), or no barrier dressing (no barrier group). The primary outcome was the incidence of any nasal injury during CPAP support, until the infant was both >30 weeks of postmenstrual age and >1250 g, unless CPAP therapy was stopped earlier. Nasal injury was regularly assessed by bedside nurses using a standardized form. RESULTS: A total of 108 preterm infants were enrolled: 53 infants in the barrier group and 55 infants in the no barrier group. Infants in the barrier group had a significantly lower rate of nasal injury compared with the no barrier group: 18 of 53 (34%) vs 31 of 55 (56%), respectively (P = .02), number needed to treat; 5 infants. No significant differences were detected in any secondary respiratory outcomes, or in the rate of common neonatal morbidities. CONCLUSIONS: Prophylactic use of a nasal barrier dressing within 48 hours of commencing treatment with binasal CPAP in very preterm or very low birth weight infants reduces nasal injury. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Register ACTRN12616000438459.

Leak Compensation During Volume Guarantee With the Dräger Babylog VN500 Neonatal Ventilator.

OBJECTIVES: To investigate how compensating for endotracheal tube leaks by targeting the leak-compensated tidal volume affects measured physiologic and ventilator variables during neonatal mechanical ventilation. DESIGN: Retrospective observational study. SETTING: A level III Neonatal ICU. PATIENTS: We enrolled 30 neonates who were ventilated using synchronized intermittent positive pressure mode with volume guarantee and had at least 12 hours of continuous detailed recording of ventilation variables. INTERVENTIONS: Infants were treated using the Dräger VN500 ventilator (Dräger, Lübeck, Germany), which uses a proprietary algorithm to measure and compensate for endotracheal tube leaks. Eleven were ventilated without leak compensation and 19 with leak compensation. MEASUREMENTS AND MAIN RESULTS: Detailed ventilation data were collected and analyzed at 1 Hz, with intermittent blood gas values. The percentage of leak was less than 20% in 73% of leak-compensated inflations, and the volume of the leak compensation was less than 1 mL/kg in 97.3% of inflations. Between the two groups, ventilation variables were comparable, except the percentage of leak that was significantly (p = 0.005) higher in the recordings with leak compensation. Without leak compensation, the mean expired tidal volume was maintained very close to the set level up to 50% leak, but with leaks greater than 50%, it declined progressively. With leak compensation, the mean leak-compensated expired tidal volume was well maintained even with leak greater than 90% although with large variability. Without leak compensation, the difference between the maximum allowed inflating pressure and the peak inflating pressure decreased progressively as the leak increased. This did not occur with leak compensation. The median PCO2 was slightly higher with leak compensation. CONCLUSIONS: During volume guarantee ventilation with a Dräger VN500 ventilator, without leak compensation the expired tidal volume declined after 50% leak. With leak compensation, the tidal volume was maintained even with a large leak. With leak compensation, there was a more stable peak inflating pressure, although the PCO2 was slightly higher.

A Comparison of the Adjustable Ranges of Inspiratory Pressurization During Pressure Controlled Continuous Mandatory Ventilation of 5 ICU Ventilators.

BACKGROUND: Faster inspiratory pressurization can improve patient-ventilator synchrony and reduce the patient's work of breathing during pressure controlled continuous mandatory (PC-CMV) ventilation. The characteristics of the pressurization ramp settings are not standardized across ventilators from different manufacturers. We performed a bench test of 5 models of ICU ventilators to examine the effects of pressurization ramp settings on the actual pressurization. METHODS: A twin-bellows lung model was used, in which one bellow simulates inspiratory muscle activity and the other simulates an adult normal lung model. We made the inspiratory effort by changing the tidal volume of the inspiratory muscle bellow. The effect of pressurization ramp settings on the performance of each ventilator was examined at 3 inspiratory effort levels (ie, none, ordinary, and strong). The pressurization ramp was set at 4 or 5 evenly divided steps from the minimum to maximum for each ventilator. The following parameters were measured: tidal volume, mean airway pressure, maximal inspiratory flow, time to maximal flow, and pressure-time products at 0.3 s (PTP0.3) and 0.5 s (PTP0.5) from the beginning of inspiration. PTP0.3 and PTP0.5 indicated levels of inspiratory pressurization. RESULTS: A proportional increase in PTP0.3 and PTP0.5 was observed with an increase in the pressurization ramp settings of the recent models of ventilators. PTP0.3 and PTP0.5 at ordinary and strong effort levels were similar in the recent models of ventilators. The actual adjustable ranges of PTP0.3 and PTP0.5 associated with change in the pressurization ramp settings differed between the 5 ventilators. CONCLUSIONS: The adjustable ranges of the pressurization were largely different among the different types of ventilators. The actual absolute inspiratory pressurization during PC-CMV varied between the different ventilators even at similar pressurization ramp settings. Users should be mindful of the differences in the pressurization ramp settings.

CPAP and EPAP elicit similar lung deflation in a non-equivalent mode in GOLD 3-4 COPD patients.

INTRODUCTION: Lung hyperinflation is associated with inspiratory muscle strength reduction, nocturnal desaturation, dyspnea, altered cardiac function and poor exercise capacity in advanced COPD. OBJECTIVES: We investigated the responses of inspiratory capacity (IC) and inspiratory muscle strength (PImax), comparing continuous positive airway pressure (CPAP) and expiratory positive airway pressure (EPAP) with the main hypothesis that there would be similar effects on lung deflation. METHODS: Eligible patients were submitted to 10 cmH2 O CPAP and EPAP on different days, under careful ECG (HR) and peripheral oxygen saturation (SpO2 ) monitoring. RESULTS: Twenty-one eligible COPD patients were studied (13 male/8 female, FEV1 % predicted of 36.5 ± 9.8). Both CPAP and EPAP demonstrated significant post-pre (Δ) changes for IC and PImax, with mean ΔIC for CPAP and EPAP of 200 ± 100 mL and 170 ± 105 mL (P = .001 for both) in 13 and 12 patients (responders) respectively. There were similar changes in % predicted IC and PImax (∼7%, P = .001 for both) for responders and poor responder/non-responder agreement depending on CPAP/EPAP mode (Kappa = .113, P = .604). There were no differences in CPAP and EPAP regarding intensity of lung deflation (P =.254) and no difference was measured regarding HR (P = .235) or SpO2 (P = .111). CONCLUSIONS: Both CPAP and EPAP presented a similar effect on lung deflation, without guaranteeing that the response to one modality would be predictive of the response to the other.

[Research advances in neonatal nasal intermittent positive pressure ventilation].

Nasal intermittent positive pressure ventilation (NIPPV) can augment nasal continuous positive airway pressure (nCPAP) by delivering intermittent positive pressure ventilation in a noninvasive way and can provide a new option for neonatal noninvasive respiratory support. NIPPV has an advantage over nCPAP in primary and post-extubation respiratory support. Moreover, it can reduce severe apnea of prematurity. Synchronized NIPPV has promising application prospects. This review article summarizes the advances in the application of NIPPV in neonatal respiratory support to promote the understanding and standardization of this technique.

High-Flow Nasal Cannula Therapy Versus Intermittent Noninvasive Ventilation in Obese Subjects After Cardiothoracic Surgery.

BACKGROUND: Obese patients are considered at risk of respiratory failure after cardiothoracic surgery. High-flow nasal cannula has demonstrated its non-inferiority after cardiothoracic surgery compared to noninvasive ventilation (NIV), which is the recommended treatment in obese patients. We hypothesized that NIV was superior to high-flow nasal cannula for preventing or resolving acute respiratory failure after cardiothoracic surgery in this population. METHODS: We performed a post hoc analysis of a randomized, controlled trial. Obese subjects were randomly assigned to receive NIV for at least 4 h/d (inspiratory pressure, 8 cm H2O; expiratory pressure, 4 cm H2O; FIO2 , 0.5) or high-flow nasal cannula delivered continuously (flow, 50 L/min, FIO2 0.5). RESULTS: Treatment failure (defined as re-intubation, switch to the other treatment, or premature discontinuation) occurred in 21 of 136 (15.4%, 95% CI 9.8-22.6%) subjects with NIV compared to 18 of 135 (13.3%, 95% CI 8.1-20.3%) subjects with high-flow nasal cannula (P = .62). No significant differences were found for dyspnea and comfort scores. Skin breakdown was significantly more common with NIV after 24 h (9.2%, 95% CI 5.0-16.0 vs 1.6%, 95% CI 1.0-6.0; P = .01). No significant differences were found for ICU mortality (5.9% for subjects with NIV vs 2.2% for subjects with high-flow nasal cannula, P = .22) or for any of the other secondary outcomes. CONCLUSIONS: Among obese cardiothoracic surgery subjects with or without respiratory failure, the use of continuous high-flow nasal cannula compared to intermittent NIV (8/4 cm H2O) did not result in a worse rate of treatment failure. Because high-flow nasal cannula presents some advantages, it may be used instead of NIV in obese patients after cardiothoracic surgery.

NeoSeal to Prevent Nasal Injury in Preterm Infants Receiving Oxygen Therapy.

PURPOSE: To determine if a foam septum protector prevents nasal injury in preterm infants receiving nasal heated humidified oxygen. DESIGN: A retrospective before and after comparative design was used. SAMPLE: Medical records of 101 preterm infants receiving either nasal continuous positive airway pressure (NCPAP) or nasal intermittent positive pressure ventilation (NIPPV) were reviewed; 50 were in the control group and 51 were in the intervention group that had the NeoSeal septum protector applied. The groups were not different in terms of gender, birth weight, gestational age, days intubated, or on days on NCPAP/NIPPV. Skin condition of nares was scored daily using the Neonatal Skin Risk Assessment Scale (NSRAS). RESULTS: Infants who had the NeoSeal applied had significantly less nasal injuries, OR = 4.08; 95% confidence interval (CI), 1.22-9.59; p = .01. The best predictors of nasal injury were gestational age and whether the NeoSeal was applied or not.

Synchronized Nasal Intermittent Positive Pressure Ventilation of the Newborn: Technical Issues and Clinical Results.

Although mechanical ventilation via an endotracheal tube has undoubtedly led to improvement in neonatal survival in the last 40 years, the prolonged use of this technique may predispose the infant to development of many possible complications including bronchopulmonary dysplasia. Avoiding mechanical ventilation is thought to be a critical goal, and different modes of noninvasive respiratory support beyond nasal continuous positive airway pressure, such as nasal intermittent positive pressure ventilation and synchronized nasal intermittent positive pressure ventilation, are also available and may reduce intubation rate. Several trials have demonstrated that the newer modes of noninvasive ventilation are more effective than nasal continuous positive airway pressure in reducing extubation failure and may also be more helpful as modes of primary support to treat respiratory distress syndrome after surfactant and for treatment of apnea of prematurity. With synchronized noninvasive ventilation, these benefits are more consistent, and different modes of synchronization have been reported. Although flow-triggering is the most common mode of synchronization, this technique is not reliable for noninvasive ventilation in neonates because it is affected by variable leaks at the mouth and nose. This review discusses the mechanisms of action, benefits and limitations of noninvasive ventilation, describes the different modes of synchronization and analyzes the technical characteristics, properties and clinical results of a flow-sensor expressly developed for synchronized noninvasive ventilation.

Nasal intermittent positive pressure ventilation in preterm infants: Equipment, evidence, and synchronization.

The use of nasal intermittent positive pressure ventilation (NIPPV) as respiratory support for preterm infants is well established. Evidence from randomized trials indicates that NIPPV is advantageous over continuous positive airway pressure (CPAP) as post-extubation support, albeit with varied outcomes between NIPPV techniques. Randomized data comparing NIPPV with CPAP as primary support, and for the treatment of apnea, are conflicting. Intrepretation of outcomes is limited by the multiple techniques and devices used to generate and deliver NIPPV. This review discusses the potential mechanisms of action of NIPPV in preterm infants, the evidence from clinical trials, and summarizes recommendations for practice.

The Use of a Fully Automated Automatic Adaptive Servoventilation Algorithm in the Acute and Long-term Treatment of Central Sleep Apnea.

BACKGROUND: Central sleep apnea (CSA), in association with obstructive disordered breathing, occurs in patients using opioids long-term and those with congestive heart failure. In these patients, treatment with CPAP frequently fails. The current adaptive servoventilation (ASV) devices are promising for the treatment of complex sleep-disordered breathing. These devices use algorithms to automatically titrate expiratory and inspiratory pressures. We hypothesized that an ASV device operating automatically would significantly reduce the frequency of breathing events in patients with mixed sleep apnea during polysomnography and with 3 months of treatment. METHODS: This was a prospective, multicenter, observational trial. Patients completed 3 nights of attended polysomnography, scored at an independent center. Twenty-seven patients with an apnea-hypopnea index (AHI) ≥ 15 and a central apnea index (CAI) ≥ 5/h underwent automated ASV titration without technician intervention. Twenty-six patients (96%) used ASV at home for 3 months. RESULTS: Patients had an AHI of 55 ± 24 (mean ± SD) and CAI of 23 ± 18 at baseline. Overnight, ASV titration improved AHI, CAI, obstructive apnea, and arousal index significantly. Patients reported better sleep quality on ASV than CPAP. Over 3 months, ASV remained effective (median AHI 11 vs four during polysomnography). Mean adherence was 4.2 h per night. Epworth Sleepiness Scale decreased from 12.8 to 7.8 (P = .001). CONCLUSIONS: The ASV device treated complex breathing disorders using automated algorithms. Compared with CPAP, patients reported improved sleep quality. Home use of ASV remained effective with acceptable adherence and improvements in daytime sleepiness. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01199042; URL: www.clinicaltrials.gov.

Effects of synchronisation during SiPAP-generated nasal intermittent positive pressure ventilation (NIPPV) in preterm infants.

OBJECTIVE: The SiPAP flow driver (Care Fusion, Dublin, Ohio, USA) offers synchronised nasal intermittent positive pressure ventilation (sNIPPV) using an abdominal capsule. This study aims to describe the accuracy and effects of synchronised NIPPV using SiPAP in preterm infants. DESIGN: Ten infants, born <28 weeks' gestation, receiving synchronised SiPAP-generated NIPPV, in 'biphasic trigger' mode, were observed. Abdominal capsule signals, delivered pressures, respiratory pattern and oxygen saturations were recorded. Tidal volume (VT), apnoeas, proportion of breaths supported by SiPAP and time between inspiration onset and SiPAP pressure rise were analysed. RESULTS: Infants were of median 26(+0) weeks' gestational age and birth weight 776 g. Mean (SD) respiratory rate (RR) was 53 (14)/min. 82% (17) of spontaneous breaths triggered a SiPAP pressure peak. Mean time between inspiration and SiPAP pressure rise was 28 (20) ms. There was no difference in VT when breaths triggered a SiPAP pressure peak compared with breaths without a pressure peak. No VT was generated by pressure peaks delivered during apnoea. Capsule signals were not recognised following >10% of breaths, resulting in asynchronous NIPPV delivery. Movements resulted in irregular SiPAP pressures and desaturation. When the RR was faster, >55/min, breaths irregularly triggered a SiPAP pressure peak (p=0.003). Compared with times when every breath resulted in a pressure peak, lower mean pressures were achieved, 7.9 vs 8.4 cm H2O (p=0.02). CONCLUSIONS: The SiPAP synchronisation system triggered rapidly with most spontaneous breaths, but did not result in larger tidal volumes. When the RR was >55/min, the SiPAP delivered fewer pressure peaks at lower pressures.

A chin-lift mask produces a patent airway more effectively than an oropharyngeal airway using the EC-clamp technique in obese patients.

OBJECTIVE: To evaluate the efficiency of ventilation using a novel chin-lift mask compared with an oropharyngeal airway (OPA) with EC-clamp technique in obese patients. METHODS: Obese patients scheduled for cholecystectomy under general anaesthesia were divided into two groups: the OPA group, in which a standard mask and OPA with the EC-clamp technique were used; the CL group, in which the chin-lift mask was used. Respiratory data were compared. RESULTS: One hundred patients were recruited and assigned to the OPA (n = 50) and CL (n = 50) groups. Compared with the OPA group, expired tidal volume, peripheral oxygen saturation (SpO2), tidal volume/peak inspiratory pressure ratio and end-tidal carbon dioxide were higher, and the peak and mean inspiratory pressures were lower, in the CL group. In the CL group, no patient had an SpO2 ≤ 95% and the lowest SpO2 was 99%, whereas in the OPA group, 23 patients had an SpO2 ≤ 95% and the lowest SpO2 was 92%. Difficult mask ventilation occurred in eight patients in the OPA group but in none in the CL group. CONCLUSION: The chin-lift mask provided a patent airway and better quality mask ventilation than an OPA with EC-clamp technique in obese patients.