Comparative evaluation of three interfaces for non-invasive ventilation: a randomized cross-over design physiologic study on healthy volunteers.

INTRODUCTION: Interface choice is crucial for non-invasive ventilation (NIV) success. We compared a new interface, the helmet next (HN), with the facial mask (FM) and the standard helmet (HS) in twelve healthy volunteers. METHODS: In this study, five NIV trials were randomly applied, preceded and followed by a trial of unassisted spontaneous breathing (SB). Baseline settings, for example, 5 cmH2O of both inspiratory pressure support (PS) and positive end-expiratory pressure (PEEP), were applied through FM, HS and HN, while increased settings (PS and PEEP of 8 cmH2O) were only applied through HS and HN. We measured flow, airway, esophageal and gastric pressures, and calculated inspiratory effort indexes and trigger delays. Comfort was assessed with a visual-analog-scale. RESULTS: We found that FM, HS and HN at baseline settings were not significantly different with respect to inspiratory effort indexes and comfort. Inspiratory trigger delay and time of synchrony (TI,synchrony) were significantly improved by FM compared to both helmets, whereas expiratory trigger delay was shorter with FM, as opposed to HS only. HN at increased settings performed better than FM in decreasing inspiratory effort measured by pressure-time product of transdiaphragmatic pressure (PTPdi)/breath (10.7 ± 9.9 versus 17.0 ± 11.0 cmH2Os), and PTPdi/min (128 ± 96 versus 204 ± 81 cmH2Os/min), and PTPdi/L (12.6 ± 9.9 versus 30.2 ± 16.8 cmH2Os/L). TI, synchrony was inferior between HN and HS at increased settings and FM. CONCLUSIONS: HN might hold some advantages with respect to interaction and synchrony between subject and ventilator, but studies on patients are needed to confirm these findings. TRIAL REGISTRATION: ClinicalTrials.gov NCT01610960.

[Chronic respiratory failure: the role of home mechanical ventilation]. / Chronische respiratorische Insuffizienz: Rolle der ausserklinischen Beatmung.

While negative pressure ventilation using cuirass respirators or iron-lung machines was prevailing in the first part of the 20th century, the polio epidemic in Copenhagen 1952 marks the turning point at which positive pressure ventilation following tracheotomy was started. Furthermore, following the introduction of facial masks and starting 1985 in Germany non-invasive positive pressure ventilation has meanwhile been developed as a routine procedure for the long-term treatment of patients with chronic ventilatory failure today. The current article provides an overview of these developments and also outlines the role of two particular national societies: "Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin (DGP) e. V." (German Medical Association of Pneumology and Ventilatory Support) and "Deutsche Interdisziplinäre Gesellschaft für außerklinische Beatmung (DIGAB) e. V." (German Interdisciplinary Society for Home Mechanical Ventilation).

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.

Non-invasive high-frequency oscillatory ventilation in preterm infants: a randomised controlled cross-over trial.

OBJECTIVE: Non-invasive high-frequency oscillatory ventilation (nHFOV) has recently been described as a novel mode of respiratory support for premature infants. This study was designed to determine whether nHFOV decreases CO2 partial pressure (pCO2) in premature infants more effectively than non-invasive continuous positive airway pressure (nCPAP). DESIGN: Non-blinded prospective randomised controlled cross-over study. SETTING: University Medical Center tertiary neonatal intensive care unit. PATIENTS: 26 premature infants of 27±2 weeks of gestational age after extubation or non-invasive surfactant treatment. INTERVENTIONS: Infants were treated with 4 hours of nHFOV and 4 hours of nCPAP in a cross-over design. The sequence of the ventilation mode was randomly allocated. MAIN OUTCOME MEASURES: The primary outcome measure was pCO2 of arterial or arterialised blood 4 hours after commencing the respective mode of respiratory support. Secondary outcome criteria included events of apnoea and bradycardia, respiratory rate, heart rate, pain and/or discomfort, mean airway pressure, fraction of inspired oxygen and failure of non-invasive respiratory support. RESULTS: pCO2 after 4 hours of nHFOV was similar compared with 4 hours of nCPAP (p=0.33). pCO2 was 54.8 (14.6) vs 52.7 (9.3) mm Hg mean (SD) for the nHFOV-nCPAP period (n=13) and 49.0 (8.1) vs 47.7 (9.5) mm Hg for the nCPAP-nHFOV period (n=13). There was no difference in any of the secondary outcome measures. nHFOV was terminated prematurely in five cases for predefined failure criteria (p=0.051). CONCLUSIONS: We could not demonstrate an increased carbon dioxide clearance applying nHFOV compared with nCPAP in this cohort of preterm infants. TRIAL REGISTRATION NUMBER: DRKS00007171, results.

Demand and continuous flow intermittent mandatory ventilation systems.

A mechanical lung was used to evaluate the pressure and flow characteristics of four demand and two continuous flow intermittent mandatory ventilation (IMV) systems. The amount of negative pressure required to initiate inspiratory flow and peak expiratory resistance were measured. The inspiratory pressure required to initiate flow in the demand mode was also compared to pressures generated in the assist mode. In addition, the peak expiratory resistance was measured with four commercially available exhalation valves. Results showed that the ventilator manometer measuring internal machine pressures significantly underestimated the amount of negative pressure required to open the demand valve (p less than 0.01). There are major differences in the flow and pressure characteristics among demand and continuous flow IMV systems. Systems that impose high inspiratory elastic threshold loads and expiratory flow resistive loads may have a deleterious effect on the mechanics of breathing, and thereby limit weaning success and eventually impair the recovery of certain patients in respiratory failure. The basic methodology, especially the simple technique of inserting an aneroid manometer in line next to a patient's ET tube, for measuring proximal negative inspiratory force (NIF test) can be easily applied to any and all ventilators at any practitioner's individual institution.

High frequency jet ventilation in experimental pulmonary emphysema.

The effects of high frequency jet ventilation (HFJV, f = 2 Hz and 8 Hz, I:E = 0.43, FiO2 = 0.4) were studied and compared with intermittent positive pressure ventilation (IPPV, f = 10-14 breaths/min, VT = 15 ml/kg, I:E = 0.5, FiO2 = 0.4) in 8 dogs before and after induction of panlobular emphysema (PLE). PLE increased alveolar-arterial PO2 difference (PA-aO2) during all modes of ventilation, whereas PaCO2 did not change significantly. In both periods of the study, HFJV8 Hz was less effective in terms of CO2-elimination and oxygenation. In the control-period, functional residual capacity (FRC) was 937 +/- 212 ml. The increase during HFJV (HFJV2 Hz: 1156 +/- 508 ml, HFJV8 Hz: 1153 +/- 433 ml) did not reach significance (P = 0.09). Closing volume (CV) increased from 1.5 +/- 4.3% of vital capacity (%VC) (IPPV) to 6.3 +/- 7.1%VC (HFJV2 Hz) and 10.8 +/- 9.8% VC (HFJV8 Hz), respectively. In the PLE-period, FRC and CV increased significantly to 1107 +/- 207 ml and 14.1 +/- 7.0% VC respectively during IPPV (P less than 0.05). Application of HFJV neither increased FRC (HFJV2 Hz: 1153 +/- 433 ml, HFJV8 Hz: 1005 +/- 344 nor CV 14.8 +/- 6.0% VC and 13.9 +/- 8.1% VC, respectively). It is concluded that HFJV induces no alveolar overdistension in dogs with emphysematous lungs.

Influence of SIMV plus inspiratory pressure support on VA/Q distributions during postoperative weaning.

Since the introduction of synchronized intermittent mandatory ventilation (SIMV) several advantages have been attributed to this ventilatory mode, one of them being a more homogeneous distribution of ventilation and perfusion than during controlled mechanical ventilation (CMV). Up to now no data are available to confirm whether this is true when SIMV is used in combination with inspiratory pressure support (IPS). Therefore, we compared the influence of CMV and SIMV + IPS on the distributions of ventilation and perfusion in 9 patients undergoing weaning from postoperative mechanical ventilation. Continuous distributions of ventilation and perfusion were assessed using the multiple inert gas elimination technique (MIGET). SIMV + IPS did not induce any change in the hemodynamic or oxygenation parameters, in particular CI and PaO2 remained constant. Physiological dead space (VD/VT) increased, but PaCO2 remained unchanged due to increased minute ventilation (from 9.5 +/- 0.9 l.min-1 to 11.3 #/- 1.2 l.min-1). The perfusion distributions remained unaltered; there was no change in QS/QT nor in the perfusion of the low VA/Q lung regions. This result was underscored by the unchanged dispersion of the perfusion distribution (log SDQ). The increased VD/VT was caused by increased inert gas dead space (from 22.0 +/- 9.6 to 26.8 +/- 8.7%) which was accompanied by increased ventilation of lung regions with high VA/Q ratios (10 less than VA/Q less than 100) in 3 patients. These results show that in our group of patients partial removal of CMV together with pressure support assistance of spontaneous ventilation did not induce a clinically significant loss of the efficiency of the breathing pattern.(ABSTRACT TRUNCATED AT 250 WORDS)

An experimental randomized study of six different ventilatory modes in a piglet model with normal lungs.

A randomized study of 6 ventilatory modes was made in 7 piglets with normal lungs. Using a Servo HFV 970 (prototype system) and a Servo ventilator 900 C the ventilatory modes examined were as follows: SV-20V, i.e. volume-controlled intermittent positive-pressure ventilation (IPPV); SV-20VIosc, i.e. volume-controlled ventilation (IPPV) with superimposed inspiratory oscillations; and SV-20VEf, i.e. volume-controlled ventilation (IPPV) with expiratory flush of fresh gas; HFV-60 denotes low-compressive high-frequency positive-pressure ventilation (HFPPV) and HVF-20 denotes low-compressive volume-controlled intermittent positive-pressure ventilation; and SV-20P denotes pressure-controlled intermittent positive-pressure ventilation. With all modes of ventilation a PEEP of 7.5 cm H2O was used. In the abbreviations used, the number denotes the ventilatory frequency in breaths per minute (bpm). HFV indicates that all gas was delivered via the HFV 970 unit. The ventilatory modes described above were applied randomly for at least 30 min, aiming for a normoventilatory steady state. The HFV-60 and the HFV-20 modes gave lower peak airway pressures, 12-13 cm H2O compared to approximately 17 cm H2O for the other ventilatory modes. Also the mean airway pressures were lower with the HFV modes 8-9 cm H2O compared to 11-14 cm H2O for the other modes. The gas distribution was evaluated by N2 wash-out and a modified lung clearance index. All modes showed N2 wash-out according to a two-compartment model. The SV-20P mode had the fastest wash-out, but the HFV-60 and HFV-20 ventilatory modes also showed a faster N2 wash-out than the others.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous positive airway pressure (CPAP) vs. intermittent mandatory pressure release ventilation (IMPRV) in patients with acute respiratory failure.

Intermittent Mandatory Pressure Release Ventilation (IMPRV) is a positive pressure spontaneous breathing ventilatory mode in which airway pressure is released intermittently and synchronously with patient's spontaneous expiration in order to provide ventilatory assistance. Eight critically ill patients free of any factor known to alter chest wall mechanics (group 1) and 8 critically ill patients whose spontaneous respiratory activity was markedly altered by a flail chest, or by a C5 quadraplegia and/or by the administration of opioids (group 2) were studied prospectively. CPAP and IMPRV were administered to each patient in a random order during a 1 h period using a CESAR ventilator. Gas flow, tidal volume, tracheal pressure, esophageal pressure, end-expiratory lung volume and hemodynamic parameters were measured. In group 1 patients, the ventilatory assistance provided by IMPRV was associated with a significant decrease in spontaneous tidal volume whereas all other respiratory parameters remained unchanged. In group 2 patients, IMPRV increased minute ventilation from 8.0 +/- 2.61/min to 12.2 +/- 1.81/min (p less than 0.05), decreased PaCO2 from 46 +/- 7.3 mmHg to 38 +/- 6.8 mmHg (p less than 0.05) and reduced respiratory frequency from 21 +/- 10 bpm to 14 +/- 5.7 bpm (p less than 0.07). These results show that IMPRV provides significant ventilatory assistance to patients with mild acute respiratory failure either by decreasing patient's contribution to minute ventilation or by increasing alveolar ventilation in presence of respiratory depression of central or peripheral origin.

An experimental randomized study of five different ventilatory modes in a piglet model of severe respiratory distress.

OBJECTIVES: To characterize different modes of pressure- or volume-controlled mechanical ventilation with respect to their short-term effects on oxygen delivery (DO2). Furthermore to investigate whether such differences are caused by differences in pulmonary gas exchange or by airway-pressure-mediated effects on the central hemodynamics. DESIGN: After inducing severe respiratory distress in piglets by removing surfactant, 5 ventilatory modes were randomly and sequentially applied to each animal. SETTING: Experimental laboratory of a university department of Anesthesiology and Intensive Care. ANIMALS: 15 piglets after repeated bronchoalveolar lavage. INTERVENTIONS: Volume-controlled intermittent positive-pressure ventilation (IPPV) with either 8 or 15 cmH2O PEEP; pressure-controlled inverse ratio ventilation (IRV); pressure-controlled high-frequency positive-pressure ventilation (HFPPV) and pressure-controlled high frequency ventilation with inspiratory pulses superimposed (combined high frequency ventilation, CHFV). The prefix (L) indicates that lavage has been performed. MEASUREMENTS AND RESULTS: Measurements of gas exchange, airway pressures, hemodynamics, functional residual capacity (using the SF6 method), intrathoracic fluid volumes (using a double-indicator dilution technique) and metabolism were performed during ventilatory and hemodynamic steady state. The peak inspiratory pressures (PIP) were significantly higher in the volume-controlled low frequency modes (43 cmH2O for L-IPPV-8 and L-IPPV-15) than in the pressure-controlled modes (39 cmH2O for L-IRV, 35 cmH2O for L-HFPPV and 33 cmH2O for L-CHFV, with PIP in the high-frequency modes being significantly lower than in inverse ratio ventilation). The mean airway pressure (MPAW) after lavage was highest with L-IRV (26 cmH2O). In the ventilatory modes with a PEEP > 8 cmH2O PaO2 did not differ significantly and beyond this "opening threshold" MPAW did not further improve PaO2. Central hemodynamics were depressed by increasing airway pressures. This is especially true for L-IRV in which we found the highest MPAW and at the same time the lowest stroke index (74% of IPPV). CONCLUSIONS: In this model, as far as oxygenation is concerned, it does not matter in which specific way the airway pressures are produced. As far as oxygen transport is concerned, i.e. aiming at increasing DO2, we conclude that optimizing the circulatory status must take into account the circulatory influence of different modes of positive pressure ventilation.

Treatment of type I spinal muscular atrophy with noninvasive ventilation and gastrostomy feeding.

Type I spinal muscular atrophy (SMA) is a rapidly progressive, degenerative neuromuscular disease of infancy. In severe SMA, weakness, hypotonia, and bulbar involvement lead to progressive respiratory insufficiency and swallowing dysfunction, which are frequently complicated by aspirations. There are few studies reported in the literature that address the respiratory management of type I SMA. This article reports the results of treating four patients with infantile SMA with noninvasive positive pressure ventilation and gastrostomy feeding. All patients had gastroesophageal reflux disease, which was managed medically. Despite these therapies, survival was only 1 to 3.5 months after presenting with severe aspirations. The treatment strategy, which can be effective in less rapidly progressive neuromuscular diseases, did not alter the very poor prognosis of type I SMA. The treatment options are reviewed, and a strategy designed to optimize quality of life for infants with this fatal disease is presented.

A consideration of neonatal resuscitation.

There are currently two major areas of resuscitation of the newborn which have come into question: the use of intermittent positive pressure ventilation and the use of oxygen. There is evolving evidence that volutrauma associated with IPPV, especially in the premature infant, may induce changes in the lung which can lead to chronic lung disease. There is reason to believe that the use of continuous positive airway pressure in premature infants who are making respiratory efforts may be less harmful than the use of IPPV. With regard to the use of oxygen, it is clear that most infants can be successfully resuscitated with room air. Although we can identify markers for oxidative stress in newborns when resuscitated with 100% oxygen, the clinical importance of these markers remain an open issue. If the presence of these markers after resuscitation is shown to relate to clinical problems, then the use of oxygen may need to be considered.

[Intermittent mandatory ventilation]. / Ventilación mandatoria intermitente.

Intermittent mandatory ventilation (IMV) is a mode of ventilation that allows the patient to make spontaneous breaths during the expiratory phase of mandatory ventilator breaths. There are two types of IMV according to whether respirator breaths are synchronized with the patient's respiratory efforts: Non-synchronized IMV and synchronized IMV (SIMV), and according to whether SIMV is volume- or pressure programmed. The main advantage of SIMV is that the respirator delivers the preset ventilator pressure and rate while allowing the patient to breath spontaneously, thus facilitating progressive weaning from mechanical ventilation. It diminishes the risk of barotrauma, produces less hemodynamic com-promise than control ventilation, reduces atrophy of respiratory muscles and the need for sedation and muscle relaxation and can be associated with pressure support ventilation.

[Artificial respiration at home seen in a 5-year perspective. Established treatment, but remarkable differences among the counties]. / Hemrespiratorbehandling i ett femårsperspektiv. Etablerad behandling, men anmärkningsvärda skillnader mellan landstingen.

The Swedish prevalence of home mechanical ventilation is 8.2 per 100.000 with 10% annual increase. There is a large span (20 vs 2 per 100.000) between "top level" and "low level" counties, in spite of Sweden's homogeneous publicly financed system for provision of health care. The largest prevalence difference was found in patients with obstructive sleep apnoea syndrome (Pickwickian type), but their blood gas and lung function data were identical in top-level vs low-level counties. These data refute the hypothesis of overprescription in top-level counties. We conclude that the most probable explanation is under-recognition of patients in low-level counties.

[Long-term outcome of patients treated by home mechanical ventilation].

To investigate the long-term survival of 95 patients treated by home mechanical ventilation, we prospectively analyzed the outcomes of their cases (treatments: 34, tracheostomy; 61, non-invasive methods) using the database of the local registration system in Aichi Prefecture. The annual actuarial probability of continuing home mechanical ventilation for the tracheostomized patients was 97.0% in the first year, 79.0% in the second year, 79.0% in the third year, and 69.2% in the fourth year, and those for the patients treated by non-invasive ventilation were 85.6%, 67.9%, 56.8%, and 46.4%, respectively. In comparison with patients with neuromuscular disease, patients with respiratory disease (both tracheostomized and non-tracheostomized) tended to show a lower continuation ratio, but the difference was not statistically significant. These data were comparable to those of previous reports, suggesting that home respiratory care in Aichi Prefecture satisfied the normal standards of quality.

Portable volume ventilators.

We evaluated 5 portable volume ventilators from 4 manufacturers. Ventilation requirements in general patient care areas in the hospital differ from those for home care; therefore, we considered use of the units for these applications separately. None of the units are ideal for either application because of the limitations and risks of each ventilator. All units are rated Conditionally Acceptable, but are ranked for hospital use only. The primary conditions for acceptable hospital use are that exhaled-volume monitoring be performed for all patients and that O2 monitoring be performed both when setting FIO2 and continuously when FIO2 levels are critical. For home care, users should carefully weigh the advantages and disadvantages of each unit and base their choice of a unit primarily on individual patient needs, ease of use, and safety factors.

Neonatal non-invasive respiratory support: synchronised NIPPV, non-synchronised NIPPV or bi-level CPAP: what is the evidence in 2013?

Nasal continuous positive airway pressure (NCPAP) has proven to be an effective mode of non-invasive respiratory support in preterm infants; however, many infants still require endotracheal ventilation, placing them at an increased risk of morbidities such as bronchopulmonary dysplasia. Several other modes of non-invasive respiratory support beyond NCPAP, including synchronised and non-synchronised nasal intermittent positive pressure ventilation (SNIPPV and nsNIPPV) and bi-level positive airway pressure (BiPAP) are now also available. These techniques require different approaches, and the exact mechanisms by which they act remain unclear. SNIPPV has been shown to reduce the rate of reintubation in comparison to NCPAP when used as post-extubation support, but the evidence for nsNIPPV and BiPAP in this context is less convincing. There is some evidence that NIPPV (whether synchronised or non-synchronised) used as primary respiratory support is beneficial, but the variation in study methodology makes this hard to translate confidently into clinical practice. There is currently no evidence to suggest a reduction in mortality or important morbidities such as bronchopulmonary dysplasia, with NIPPV or BiPAP in comparison to NCPAP, and there is a lack of appropriately designed studies in this area. This review discusses the different approaches and proposed mechanisms of action of SNIPPV, nsNIPPV and BiPAP, the challenges of applying the available evidence for these distinct modalities of non-invasive respiratory support to clinical practice, and possible areas of future research.

Practices of use of nasal intermittent positive pressure ventilation (NIPPV) in neonatology in northeastern Brazil.

OBJECTIVES: To investigate the use of nasal intermittent positive pressure ventilation (NIPPV) in level three neonatal intensive care units (NICU) in northeastern Brazil. METHODS: This observational cross-sectional survey was conducted from March 2009 to January 2010 in all level three NICUs in northeastern Brazil that are registered in the Brazilian Registry of Health Establishments (Cadastro Nacional de Estabelecimentos de Saúde, CNES) of the Ministry of Health. Questionnaires about the use of NIPPV were sent to the NICU directors in each institution. Statistical analysis was conducted using the software Epi-Info 6.04 and double data entry. A chi-square test was used to compare variables, and the level of statistical significance was set at p ≤ 0.05. RESULTS: This study identified 93 level three NICUs in northeastern Brazil registered in CNES, and 87% answered the study questionnaire. Most classified themselves as private institutions (30.7%); 98.7% used NIPPV; 92.8% adapted mechanical ventilators for NIPPV and used short binasal prongs as the interface (94.2%). Only 17.3% of the units had a protocol for the use of NIPPV. Mean positive inspiratory pressure and positive end-expiratory pressure were 20.0 cmH2O (standard deviation [SD]: 4.47) and 5.0 cmH2O (SD: 0.84). CONCLUSION: NICUs in northeastern Brazil use nasal intermittent positive pressure ventilation, but indications and ventilation settings are not the same in the different institutions.

The proper tidal volume target using volume guarantee ventilation in the course of neonatal respiratory distress syndrome: a crucial endpoint.

Volume guarantee ventilation (VGV) is an optional ventilation mode which has become the most widely and extensively studied in the last 10 years in premature infants. Nonetheless, theoretical expected endpoints are intriguing and even though VGV has not yet become 'the' standard ventilation mode, a great deal of information has been acquired and stored. In our experience, VGV during the course of respiratory distress syndrome is useful and can be considered a standard ventilation mode. Weaning occurs in real time as described earlier, and synchronized intermittent positive pressure ventilation and pressure support ventilation (PSV) seem to be the preferred combined modes. Management during the acute phase requires more care since several sudden changes take place in both the lung mechanics and clinical behavior. The software is designed to protect the lung, and subsequently, sudden changes in lung compliance following iatrogenic procedures such as surfactant administration are powerfully counteracted. VGV has been extensively studied and the proposed algorithm has been found to function as planned. Although the 'superiority' of one method over another cannot be demonstrated, the use of new technologies require 'a staff learning curve' and homogeneity of treatment, while at the same time other factors, such as patient heterogeneity or illness phase, should be taken into due account.