High-frequency Percussive Ventilation Research Articles

Benefits of intratracheal and extrathoracic high-frequency percussive ventilation in a model of capnoperitoneum.

Abdominal inflation with CO2 is used to facilitate laparoscopic surgeries, however, providing adequate mechanical ventilation in this scenario is of major importance during anesthesia management. We characterized high-frequency percussive ventilation (HFPV) in protecting from the gas exchange and respiratory mechanical impairments during capnoperitoneum. In addition, we aimed to assess the difference between conventional pressure-controlled mechanical ventilation (CMV) and HFPV modalities generating the high-frequency signal intratracheally (HFPVi) or extrathoracally (HFPVe). Anesthetized rabbits (n = 16) were mechanically ventilated by random sequences of CMV, HFPVi, and HFPVe. The ventilator superimposed the conventional waveform with two high-frequency signals (5 Hz and 10 Hz) during intratracheal HFPV (HFPVi) and HFPV with extrathoracic application of oscillatory signals through a sealed chest cuirass (HFPVe). Lung oxygenation index ([Formula: see text]/[Formula: see text]), arterial partial pressure of carbon dioxide ([Formula: see text]), intrapulmonary shunt (Qs/Qt), and respiratory mechanics were assessed before abdominal inflation, during capnoperitoneum, and after abdominal deflation. Compared with CMV, HFPVi with additional 5-Hz oscillations during capnoperitoneum resulted in higher [Formula: see text]/[Formula: see text], lower [Formula: see text], and decreased Qs/Qt. These improvements were smaller but remained significant during HFPVi with 10 Hz and HFPVe with either 5 or 10 Hz. The ventilation modes did not protect against capnoperitoneum-induced deteriorations in respiratory tissue mechanics. These findings suggest that high-frequency oscillations combined with conventional pressure-controlled ventilation improved lung oxygenation and CO2 removal in a model of capnoperitoneum. Compared with extrathoracic pressure oscillations, intratracheal generation of oscillatory pressure bursts appeared more effective. These findings may contribute to the optimization of mechanical ventilation during laparoscopic surgery.NEW & NOTEWORTHY The present study examines an alternative and innovative mechanical ventilation modality in improving oxygen delivery, CO2 clearance, and respiratory mechanical abnormalities in a clinically relevant experimental model of capnoperitoneum. Our data reveal that high-frequency oscillations combined with conventional ventilation improve gas exchange, with intratracheal oscillations being more effective than extrathoracic oscillations in this clinically relevant translational model.

Venovenous extracorporeal membrane oxygenation for respiratory failure refractory to high frequency percussive ventilation

BackgroundHigh frequency percussive ventilation (HFPV) has demonstrated improvements in gas exchange, but not in clinical outcomes. ObjectivesWe utilize HFPV in patients failing conventional ventilation (CV), with rescue venovenous extracorporeal membrane oxygenation (VV ECMO) reserved for failure of HFPV, and we describe our experience with such a strategy. MethodsAll adult patients (age >18 years) placed on HFPV for failure of CV at a single institution over a 10-year period were included. Those maintained on HFPV were compared to those that failed HFPV and required VV ECMO. Survival was compared to expected survival after upfront VV ECMO as estimated by VV ECMO risk prediction models. ResultsSixty-four patients were placed on HFPV for failure of CV over a 10-year period. After HFPV initiation, the P/F ratio rose from 76mmHg to 153.3mmHg in the 69 % of patients successfully maintained on HFPV. The P/F ratio only rose from 60.3mmHg to 67mmHg in the other 31 % of patients, and they underwent rescue ECMO with the P/F ratio rising to 261.6mmHg. The P/F ratio continued to improve in HFPV patients, while it declined in ECMO patients, such that at 24 h, the P/F ratio was greater in HFPV patients. The strongest independent predictor of failure of HFPV requiring rescue VV ECMO was a lower pO2 (p = .055). Overall in-hospital survival (59.4 %) was similar to that expected with upfront ECMO (RESP score: 57 %). ConclusionsHFPV demonstrated significant and sustained improvements in gas exchange and may obviate the need for ECMO and its associated complications.

Neonatal resuscitation with continuous chest compressions and high frequency percussive ventilation in preterm lambs.

Cerebral oxygen delivery (cDO2) is low during chest compressions (CC). We hypothesized that gas exchange and cDO2 are better with continuous CC with high frequency percussive ventilation (CCC + HFPV) compared to conventional 3:1 compressions-to-ventilation (C:V) resuscitation during neonatal resuscitation in preterm lambs with cardiac arrest induced by umbilical cord compression. Fourteen lambs in cardiac arrest were randomized to 3:1 C:V resuscitation (90CC + 30 breaths/min) per the Neonatal Resuscitation Program guidelines or CCC + HFPV (120CC + HFPV continuously). Intravenous epinephrine was given every 3 min until return of spontaneous circulation (ROSC). There was no difference in the incidence and time to ROSC between both groups. Median (IQR) PaCO2 was significantly lower with CCC + HFPV during CC, at ROSC and 15 min post-ROSC-[104 (99-112), 83 (77-99), and 43 (40-64)], respectively compared to 3:1 C:V-[149 (139-167), 153 (143-168), and 153 (138-178) mmHg. PaO2 and cDO2 were higher with CCC + HFPV during CC and at ROSC. PaO2 was similar 15 min post-ROSC with a lower FiO2 in the CCC + HFPV group 0.4 (0.4-0.5) vs. 1 (0.6-1). In preterm lambs with perinatal cardiac-arrest, continuous chest compressions with HFPV does not improve ROSC but enhances gas exchange and increases cerebral oxygen delivery compared to 3:1 C:V during neonatal resuscitation. Ventilation is the most important intervention in newborn resuscitation. Currently recommended 3:1 compression-to-ventilation ratio is associated with hypercarbia and poor oxygen delivery to the brain. Providing uninterrupted continuous chest compressions during high frequency percussive ventilation is feasible in a lamb model of perinatal cardiac arrest, and demonstrates improved gas exchange and oxygen delivery to the brain. This is the first study in premature lambs evaluating high frequency percussive ventilation with asynchronous chest compressions and lays the groundwork for future clinical studies to optimize gas exchange and hemodynamics during chest compressions in newborns.

60 A Retrospective Review of High-Frequency Percussive Ventilation in Inhalation Injury

Abstract Introduction Inhalation injury (II) is a major contributor to mortality in burn patients. These patients often require mechanical ventilation, but there is no clear consensus on optimal ventilatory strategy for this population. Previous studies in patients with acute respiratory distress syndrome (ARDS) demonstrated that high frequency percussive ventilation (HFPV) improved oxygenation and mobilization of airway secretions. However, HFPV in the context of II remains poorly studied. We hypothesized that for these patients, use of HFPV in addition to conventional mechanical ventilation (CMV) would reduce complications and decrease mortality compared to patients treated with CMV only. Methods We conducted a retrospective chart review of 200 patients admitted to a burn center from February 2008 - January 2019 with burns and/or II and ventilated either with CMV alone or with CMV + HFPV. Patients who were under the age of 18 or who received mechanical ventilation for less one day were excluded. Information including patient demographics and comorbidities, percent total body surface area burned, ventilation method, length of stay, complications, and outcomes were collected. Two-sample comparisons were performed by using score test for proportions and Wilcoxon rank sum test for continuous variables with significance defined as p< 0.05. Results Of 200 patients studied, 84 received CMV + HFPV and 116 received CMV alone. There was no difference in mortality between groups (CMV+HFPV 39.3% vs CMV 31.0%; p=0.23). There was also similar incidence of pneumonia (CMV+HFPV 53.6% vs CMV alone 63.8%; p=0.15), pneumothorax, ARDS, and sepsis. Patients on CMV + HFPV had a greater incidence of acute kidney injury (CMV+HFPV 60.7% versus CMV alone 43.1%; p=0.014) and reduced development of wound complications (CMV+HFPV 7.1% versus CMV alone 16.4%; p=0.05). In surviving patients (n=131), length of hospital stay was not significantly different between groups. Conclusions These single-center results do not support the use of CMV + HFPV rather than CMV alone in patients with II. Further research in this area, including larger multi-center studies, is warranted. Applicability of Research to Practice This is a hypothesis-generating study that adds to the currently limited understanding of best practice for managing patients with II.

Benefits of secretion clearance with high frequency percussive ventilation in tracheostomized critically ill patients: a pilot study

Clearance of secretions remains a challenge in ventilated patients. Despite high-frequency percussive ventilation (HFPV) showing benefits in patients with cystic fibrosis and neuromuscular disorders, very little is known about its effects on other patient categories. Therefore, we designed a physiological pilot study investigating the effects on lung aeration and gas exchange of short HFPV cycles in tracheostomized patients undergoing mechanical ventilation. Electrical impedance tomography (EIT) was recorded at baseline (T0) by a belt wrapped around the patient's chest, followed by the HFPV cycle lasting 10 min. EIT data was collected again after the HFPV cycle (T1) as well as after 1 h (T2) and 3 h (T3) from T0. Variation from baseline of end-expiratory lung impedance (∆EELI), tidal variation (TIV) and global inhomogeneity index (GI) were computed. Arterial blood was also taken for gas analysis. HFPV cycle significantly improved the ∆EELI at T1, T2 and T3 when compared to baseline (p < 0.05 for all comparisons). The ratio between arterial partial pressure and inspired fraction of oxygen (PaO2/FiO2) also increased after the treatment (p < 0.001 for all comparison) whereas TIV (p = 0.132) and GI (p = 0.114) remained unchanged. Short cycles of HFPV superimposed to mechanical ventilation promoted alveolar recruitment, as suggested by improved ∆EELI, and improved oxygenation in tracheostomized patients with high load of secretion.Trial Registration Prospectively registered on www.clinicaltrials.gov (NCT05200507; dated 6th January 2022).

Newer techniques of humidification and secretion clearance

This paper begins with a review of airway anatomy, physiology of airway secretions, alterations in disease, and the importance of the mucociliary escalator, especially in airway disease states (asthma, COPD, cystic fibrosis, bronchiectasis etc). Alternatives to treating mild to moderate hypoxemia with high flow nasal cannula oxygen (HFNCO) such as Vapotherm are mentioned. A relatively new technique called Intrapulmonary Percussive Ventilation (IPV®) seems very effective in secretion removal. A newer device called CoughAssist™ assists cough by mechanical insufflation-exsufflation and is very useful in neurological disease. The review then focuses on High Frequency Percussive Ventilation (HFPV), otherwise known as Volumetric Diffusive Ventilation (VDR®). Lastly, the use of biphasic cuirass ventilation for secretion removal has been described.

High frequency percussive ventilation: An asset to existing ventilation modi in intraoperative care?

High frequency percussive ventilation (HFPV) is a ventilation mode that combines positive pressure ventilation with some advantages of high frequency ventilation. During HFPV, a pulsatile flow is generated with high frequency and low volumes. HFPV has been used in the intensive care unit (ICU) for several decades, in case of insufficient conventional positive pressure ventilation. However, literature on its use in intraoperative care is scarce. We hypothesize that HFPV might be a better alternative to existing ventilation modi during selected operative procedures or in patients with severely compromised pulmonary and/or cardiac function. In this paper, we explain the HFPV system, we zoom in on the physiological effects of HFPV, and we describe its potential role in the intraoperative setting. Results of existing studies show that, compared to other conventional ventilation modes, HFPV improves oxygenation and ventilation without jeopardizing hemodynamics. However, because of the low quality evidence regarding physiological effects and clinical effectiveness, and due to the complicated design and set-up of the HFPV ventilator, the use of HFPV in intraoperative care is currently very limited. We conclude that HFPV could potentially be an interesting ventilation mode for procedures requiring minimal respiratory motion or low airway pressures, however larger (comparative) study trials are required to evaluate its usability in the operating room in patients with compromised pulmonary and/or cardiac function.

Expiratory high-frequency percussive ventilation: a novel concept for improving gas exchange

BackgroundAlthough high-frequency percussive ventilation (HFPV) improves gas exchange, concerns remain about tissue overdistension caused by the oscillations and consequent lung damage. We compared a modified percussive ventilation modality created by superimposing high-frequency oscillations to the conventional ventilation waveform during expiration only (eHFPV) with conventional mechanical ventilation (CMV) and standard HFPV.MethodsHypoxia and hypercapnia were induced by decreasing the frequency of CMV in New Zealand White rabbits (n = 10). Following steady-state CMV periods, percussive modalities with oscillations randomly introduced to the entire breathing cycle (HFPV) or to the expiratory phase alone (eHFPV) with varying amplitudes (2 or 4 cmH2O) and frequencies were used (5 or 10 Hz). The arterial partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were determined. Volumetric capnography was used to evaluate the ventilation dead space fraction, phase 2 slope, and minute elimination of CO2. Respiratory mechanics were characterized by forced oscillations.ResultsThe use of eHFPV with 5 Hz superimposed oscillation frequency and an amplitude of 4 cmH2O enhanced gas exchange similar to those observed after HFPV. These improvements in PaO2 (47.3 ± 5.5 vs. 58.6 ± 7.2 mmHg) and PaCO2 (54.7 ± 2.3 vs. 50.1 ± 2.9 mmHg) were associated with lower ventilation dead space and capnogram phase 2 slope, as well as enhanced minute CO2 elimination without altering respiratory mechanics.ConclusionsThese findings demonstrated improved gas exchange using eHFPV as a novel mechanical ventilation modality that combines the benefits of conventional and small-amplitude high-frequency oscillatory ventilation, owing to improved longitudinal gas transport rather than increased lung surface area available for gas exchange.

SHAKEN, NOT STIRRED: HIGH FREQUENCY PERCUSSIVE VENTILATION AS A SALVAGE THERAPY IN SEVERE ARDS DUE TO COVID-19

TOPIC: Critical Care TYPE: Original Investigations PURPOSE: The Covid-19 pandemic has necessitated alternative strategies to treat severe Acute Respiratory Distress Syndrome (ARDS) and refractory hypoxemia. High frequency percussive ventilation (HFPV) is delivered via a hybrid ventilatory mode merging low-frequency, time cycled and pressure-limited normal volume convective ventilation with high-frequency low-volume pulsatile ventilation. This hybrid mode of ventilation creates a countercurrent flow of air which mobilizes secretions and improves gas exchange. HFPV theoretically achieves alveolar recruitment at lower peak airway pressures compared to conventional ventilation (CV), thus reducing barotrauma and ventilator-induced lung injury. Benefit from HFPV has mainly been shown in burn patients, but it has also been used in ARDS as a rescue therapy. Here, we describe our experience with HFPV in our patients with COVID-19-related ARDS in a Northern California county hospital. METHODS: From January 2020 through March 2021, 18 patients with Covid-19-related ARDS were placed on HFPV at a public tertiary care center. Data regarding demographics, complications during HFPV, ventilation settings, P/F ratios prior to and on HFPV, and hospital outcomes was collected for these patients. RESULTS: 12 men and 6 women ranging from 31-73 years of age (mean age 57 years) with Covid-19-related ARDS utilized HFPV. All patients during their ventilatory course received inhaled nitric oxide. 78% of the patients (n=14) had P/F ratios < 100 prior to being transitioned from CV. Approximately 33% of these patients (n=6) were found to have pneumothorax or pneumo-mediastinum while on HFPV. The mean age of survivors was 51 years old, whereas the mean age of non-survivors was 62 years old. Mean duration on HFPV ventilator among survivors was 15.9 days, versus 11.5 days in non-survivors. Survival rate was 44% in our cohort (n=8), and 7 of these 8 surviving patients underwent tracheostomy. Mean length of total mechanical ventilation (CV plus HFPV) until tracheostomy or extubation in all survivors was 32.3 days. CONCLUSIONS: Our small cohort showed a survival rate of 44% when placing patients with COVID-19-related ARDS on HFPV. Despite the limitations of our study, including small sample size, lack of randomization, and the presence confounding factors effecting outcomes, our study reflects a potential role for HFPV as a therapy for refractory hypoxemia in COVID-19-related ARDS. Future studies are needed to investigate a possible role of HFPV in this population. CLINICAL IMPLICATIONS: Clinical implications of this experience and potential future studies may lead to usage of HFPV as a rescue mode of ventilation for COVID-19-related ARDS. DISCLOSURES: No relevant relationships by Umang Barvalia, source=Web Response No relevant relationships by Weichia Chen, source=Web Response No relevant relationships by Heng Duong, source=Web Response No relevant relationships by Amit Gohil, source=Web Response No relevant relationships by Eric Hsiao, source=Web Response No relevant relationships by Craig Ivie, source=Web Response No relevant relationships by Neharika Khurana, source=Web Response No relevant relationships by Vibha Mohindra, source=Web Response No relevant relationships by Halley Tsai, source=Web Response No relevant relationships by John Wehner, source=Web Response

USE OF HIGH FREQUENCY PERCUSSIVE VENTILATION FOR ARDS

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: High frequency percussive ventilation (HFPV) is a method of ventilation that delivers biphasic percussive microvolumes in a time-cycled, pressure limited fashion. The goal is to increase recruitment of alveoli burdened by secretions or atelectasis to improve gas exchange for those failing conventional ventilation. HFPV has been utilized in the acute inhalation injury population; however, its use has spread to the medical community as a rescue method in acute respiratory distress (ARDS) patients. CASE PRESENTATION: A 24-year-old male with a past medial history of type 2 diabetes, obstructive sleep apnea, and obesity presented to the Emergency Department for worsening epigastric pain, nausea, and vomiting. He was ill appearing with diffuse abdominal pain, guarding, and rebound. Pertinent labs included a lipase of 3,600 U/L and triglycerides of 1,700 mg/dL. Computed tomography (CT) of the abdomen and pelvis revealed severe pancreatic edema with a non-enhancing pancreatic tail concerning for necrosis. He was admitted to the Intensive Care Unit and started on crystalloid infusion and continuous insulin. He developed progressive tachypnea and ultimately required intubation for severe hypoxemia. He further decompensated with worsening fevers and hypotension, requiring initiation of broad-spectrum antibiotics and vasopressors. Despite the insulin infusion, the patient's triglycerides increased to 9,500 mg/dL and he was started on therapeutic plasma exchange. Echocardiogram did not reveal evidence of left ventricular dysfunction. Chest x-ray showed worsening bilateral pulmonary infiltrates suggestive of ARDS. Despite a lung-protective, volume-controlled method of ventilation, the patient continued to exhibit high plateau and driving pressures. Given his significantly distended abdomen and high bladder pressures, he was unable to tolerate prone positioning. PaO2/FiO2 ratio (P/F ratio) was as low as 91. Subsequently he underwent cannulation for veno-venous extracorporeal membrane oxygenation (VV-ECMO). His secretion burden remained high and CT chest revealed dense atelectasis. He was then switched to HFPV for better secretion management and improvement in oxygenation. After 48 hours of HFPV, he had significant improvement in his atelectasis on CT chest and P/F ratio. After eight days, he was decannulated from VV-ECMO and later extubated. DISCUSSION: Our patient experienced known severe complications from hypertriglyceride-induced pancreatitis. His ARDS improved robustly with HFPV with VV-ECMO support. In centers with experience with this type of ventilation, it can be a powerful tool for patients suffering from inhalation injury, high-secretion pneumonias, and ARDS. CONCLUSIONS: Though HFPV does not have a dense volume of data supporting its use in ARDS, in the appropriately selected patient it can provide a safe and efficient way of improving lung recruitment, gas exchange, and potentially outcomes. REFERENCE #1: Godet T, Jabaudon M, Blondonnet R, Tremblay A, Audard J, Rieu B, Pereira B, Garcier JM, Futier E, Constantin JM. High frequency percussive ventilation increases alveolar recruitment in early acute respiratory distress syndrome: an experimental, physiological and CT scan study. Crit Care. 2018 Jan 11;22(1):3. REFERENCE #2: Spapen H, Borremans M, Diltoer M. Van Gorp V, Nguyen D, Honore P. (2014). High-frequency percussive ventilation in severe acute respiratory distress syndrome: A single center experience. Journal of Anesthesiology Clinical Pharmacology. 30(1):65-70. DISCLOSURES: No relevant relationships by Alaynna Kears, source=Web Response No relevant relationships by Christopher Lenivy, source=Web Response No relevant relationships by Kaitlyn Musco, source=Web Response No relevant relationships by Roshun Sangani, source=Web Response No relevant relationships by Daniel Schwed Lustgarten, source=Web Response

A narrative review of advanced ventilator modes in the pediatric intensive care unit.

Respiratory failure is a common reason for pediatric intensive care unit admission. The vast majority of children requiring mechanical ventilation can be supported with conventional mechanical ventilation (CMV) but certain cases with refractory hypoxemia or hypercapnia may require more advanced modes of ventilation. This paper discusses what we have learned about the use of advanced ventilator modes [e.g., high-frequency oscillatory ventilation (HFOV), high-frequency percussive ventilation (HFPV), high-frequency jet ventilation (HFJV) airway pressure release ventilation (APRV), and neurally adjusted ventilatory assist (NAVA)] from clinical, animal, and bench studies. The evidence supporting advanced ventilator modes is weak and consists of largely of single center case series, although a few RCTs have been performed. Animal and bench models illustrate the complexities of different modes and the challenges of applying these clinically. Some modes are proprietary to certain ventilators, are expensive, or may only be available at well-resourced centers. Future efforts should include large, multicenter observational, interventional, or adaptive design trials of different rescue modes (e.g., PROSpect trial), evaluate their use during ECMO, and should incorporate assessments through volumetric capnography, electric impedance tomography, and transpulmonary pressure measurements, along with precise reporting of ventilator parameters and physiologic variables.

High-Frequency Percussive Ventilation in Cystic Fibrosis Patients With Acute Respiratory Failure: A Case Series.

Acute respiratory failure in cystic fibrosis carries a high risk of mortality. The optimal mode of mechanical ventilation (MV) in this population is not well established. In this case series, we identified patients with cystic fibrosis who were ventilated with high-frequency percussive ventilation (HFPV) at our institution and describe their characteristics and outcomes. The use of high-frequency percussive ventilation has been sparsely described in the literature. This case series could serve as hypothesis-generating for future research.

Enhanced Deep-Inspiration Breath Hold Superior to High-Frequency Percussive Ventilation for Respiratory Motion Mitigation: A Physiology-Driven, MRI-Guided Assessment Toward Optimized Lung Cancer Treatment With Proton Therapy

Background: To safely treat lung tumors using particle radiation therapy (PRT), motion-mitigation strategies are of critical importance to ensure precise irradiation. Therefore, we compared applicability, effectiveness, reproducibility, and subjects' acceptance of enhanced deep-inspiration breath hold (eDIBH) with high-frequency percussive ventilation (HFPV) by MRI assessment within 1 month.Methods: Twenty-one healthy subjects (12 males/9 females; age: 49.5 ± 5.8 years; BMI: 24.7 ± 3.3 kg/m−2) performed two 1.5 T MRI scans in four visits at weekly intervals under eDIBH and HFPV conditions, accompanied by daily, home-based breath-hold training and spirometric assessments over a 3-week period. eDIBH consisted of 8-min 100% O2 breathing (3 min resting ventilation, 5 min controlled hyperventilation) prior to breath hold. HFPV was set at 200–250 pulses min−1 and 0.8–1.2 bar. Subjects' acceptance and preference were evaluated by questionnaire. To quantify inter- and intrafractional changes, a lung distance metric representing lung topography was computed for 10 reference points: a motion-invariant spinal cord and nine lung structure contours (LSCs: apex, carina, diaphragm, and six vessels as tumor surrogates distributed equally across the lung). To parameterize individual LSC localizability, measures of their spatial variabilities were introduced and lung volumes calculated by automated MRI analysis.Results: eDIBH increased breath-hold duration by > 100% up to 173 ± 73 s at visit 1, and to 217 ± 67 s after 3 weeks of home-based training at visit 4 (p < 0.001). Measures of vital capacity and lung volume remained constant over the 3-week period. Two vessels in the lower lung segment and the diaphragm yielded a two- to threefold improved positional stability with eDIBH, whereby absolute distance variability was significantly smaller for five LSCs; ≥70% of subjects showed significantly better intrafractional lung motion mitigation under reproducible conditions with eDIBH compared with HFPV with smaller ranges most apparent in the anterior-posterior and cranial-caudal directions. Approximately 80% of subjects preferred eDIBH over HFPV, with “less discomfort” named as most frequent reason.Conclusions: Both, eDIBH, and HFPV were well-tolerated. eDIBH duration was long enough to allow for potential PRT. Variability in lung volume was smaller and position of lung structures more precise with eDIBH. Subjects preferred eDIBH over HFPV. Thus, eDIBH is a very promising tool for lung tumor therapy with PRT, and further investigation of its applicability in patients is warranted.

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.

High frequency percussive ventilation in pediatric acute respiratory failure.

High frequency percussive ventilation (HFPV) is used in acute respiratory failure, but is poorly described in pediatrics. We aimed to describe the clinical characteristics, ventilator settings, and outcomes of a large pediatric cohort, and to determine predictors of who would benefit from HFPV. Gas exchange 2 h after HFPV initiation predicts success. Single center retrospective cohort study testing association between gas exchange 2 h after HFPV initiation with success, defined a priori. Intubated children on HFPV for ≥2 h from 2012 to 2018. We described indications, ventilator settings, and gas exchange immediately before, 2 h after, and at termination of HFPV. Univariate and multivariate regression tested association of oxygenation and ventilation after HFPV initiation with success. Areas under the receiver operating characteristic (AUROC) curve and adjusted odds ratios (aORs) were computed. We performed 237 courses of HFPV in 193 children (22% non-survivors), of which 162 (68%) were successful. In univariate analysis, pH (AUROC, 0.65) and PCO2 (AUROC, 0.66) 2 h after HFPV predicted success. In multivariate analysis, pH (aOR: 1.67 per 1 SD; 95% confidence interval [CI]: 1.19-2.35), PCO2 (aOR: 0.49 per 1 SD; 95% CI: 0.31-0.79), and oxygenation index (aOR: 0.66 per 1 SD; 95% CI: 0.44-0.97) 2 h after HFPV initiation were associated with success. We describe the largest cohort of HFPV to date, with detailed description of indications and settings. Gas exchange after 2 h of HFPV was independently associated with success.

HIGH-FREQUENCY PERCUSSIVE VENTILATION IN PATIENTS WITH CYSTIC FIBROSIS WITH ACUTE RESPIRATORY FAILURE: A CASE SERIES

SESSION TITLE: Critical Care Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: To describe our experience with high-frequency percussive ventilation (HFPV) in adults with cystic fibrosis (CF) and acute respiratory failure that required invasive mechanical ventilation (IMV). Acute respiratory failure in CF carries a significant risk of morbidity and mortality. The optimal mode of mechanical ventilation (MV) in CF is unknown. HFPV has not been studied in CF patients, however there is well-known evidence about the benefits of chest physiotherapy especially intermittent percussive pressure. This suggests that the continuous percussions provided by HFPV could provide ongoing airway clearance and potentially facilitate liberation from mechanical ventilation. METHODS: This is a case series report of 10 CF patients at a tertiary care center intensive care unit who presented with acute respiratory failure requiring endotracheal intubation and were managed with HFPV. Electronic medical records were queried for respiratory failure and the use of HFPV. A total of 12 patient encounters met the criteria. One patient was excluded due to the presence of lung transplant and one patient had two separate encounters. RESULTS: There were 11 patient encounters (4 females) with CF and acute respiratory failure treated with HFPV, 6 (55%) of these survived to discharge and clinic follow-up. The median age was 30 (20–40) years. The median hospital length of stay (LOS) was 28 (15–37) days while the ICU median LOS was 9 (4–24) days. The median time spent on total MV was 4 (3–12) days and on HFPV 4 (2–11) days. The average baseline FEV1 prior to admission was 1.2 L, 31.4% of predicted. The 6 patients, who survived hospital discharge had a median age of 22 (22–34) years. Their hospital median LOS was 27.5 (14.25–37.5) days and median ICU LOS was 7 (3.75–19.25) days. They spent a median of 4 (3.75–11.25) days on total MV. Of those, a median of 2.5 (2–7.75) days were spent on HFPV. The average prior to admission baseline FEV1 was 1.3 L (35.3% of predicted) with an average follow-up FEV1 of 1.25 L (34.2% of predicted). All the patients in this cohort had documented improved airway clearance after implementing HFPV without documented complications. CONCLUSIONS: High-frequency percussive ventilation use in adult cystic fibrosis has not been reported in the literature. The hospital mortality rate of 45% is consistent with a recent nationwide cross-sectional study by Siuba, et al. In that study, 50% of the patients required IMV > 4 days. Our patients spent a median of 4 days on IMV with 64% spending ≤ 4 days (7 patients). The survivors' FEV1 improved close to baseline upon follow-up CLINICAL IMPLICATIONS: HFPV was well tolerated in our cohort with reported improvement in airway clearance without significant complications. whether HFPV leads to improved outcomes is yet to be decided. Further larger studies are needed before it can be universally recommended DISCLOSURES: No relevant relationships by Michael Crosser, source=Web Response No relevant relationships by Mohamad badr Jandali, source=Web Response No relevant relationships by Joel Mermis, source=Web Response

On some factors determining the pressure drop across tracheal tubes during high-frequency percussive ventilation: a flow-independent model.

To provide an in vitro estimation of the pressure drop across tracheal tubes (ΔPTT) in the face of given pulsatile frequencies and peak pressures (Pwork) delivered by a high-frequency percussive ventilator (HFPV) applied to a lung model. Tracheal tubes (TT) 6.5, 7.5 and 8.0 were connected to a test lung simulating the respiratory system resistive (R = 5, 20, 50 cmH2O/L/s) and elastic (C = 10, 20, and 50 mL/cmH2O) loads. The model was ventilated by HFPV with a pulse inspiratory peak pressure (work pressure Pwork) augmented in 5-cmH2O steps from 20 to 45 cmH2O, yielding 6 diverse airflows. The percussive frequency (f) was set to 300, 500 and 700 cycles/min, respectively. Pressure (Paw and Ptr) and flow (V’) measurements were performed for all 162 possible combinations of loads, frequencies, and work pressures for each TT size, thus yielding 486 determinations. For each respiratory cycle ΔPTT was calculated by subtracting each peak Ptr from its corresponding peak Paw. A non-linear model was constructed to assess the relationships between single parameters. Performance of the produced model was measured in terms of root mean square error (RMSE) and the coefficient of determination (r2). ΔPTT was predicted by Pwork (exponential Gaussian relationship), resistance (quadratic and linear terms), frequency (quadratic and linear terms) and tube diameter (linear term), but not by compliance. RMSE of the model on the testing dataset was 1.17 cmH2O, r2 was 0.79 and estimation error was lower than 1 cmH2O in 68% of cases. As a result, even without a flow value, the physician would be able to evaluate ΔPTT pressure. If the present results of our bench study could be clinically confirmed, the use of a nonconventional ventilatory strategy as HFPV, would be safer and easier.

Fluoroscopic Demonstration of Thoracic Tumor Immobilization with High Frequency Percussive Ventilation

Fluoroscopic Demonstration of Thoracic Tumor Immobilization with High Frequency Percussive Ventilation

High frequency percussive ventilation for respiratory immobilization in radiotherapy.

High frequency percussive ventilation (HFPV) employs high frequency low tidal volumes (100-400 bursts/min) to provide respiration in awake patients while simultaneously reducing respiratory motion. The purpose of this study is to evaluate HFPV as a technique for respiratory motion immobilization in radiotherapy. In this study fifteen healthy volunteers (age 30-75 y) underwent HFPV using three different oral interfaces. We evaluated each HFPV oral interface device for compliance, ease of use, comfort, geometric interference, minimal chest wall motion, duty cycle and prolonged percussive time. Their chest wall motion was monitored using an external respiratory motion laser system. The percussive ventilations were delivered via an air driven pneumatic system. All volunteers were monitored for PO2 and tc-CO2 with a pulse oximeter and CO2 Monitoring System. A total of N = 62 percussive sessions were analyzed from the external respiratory motion laser system. Chest-wall motion was well tolerated and drastically reduced using HFPV in each volunteer evaluated. As a result, we believe HFPV may provide thoracic immobilization during radiotherapy, particularly for SBRT and pencil beam scanning proton therapy.

High Frequency Percussive Ventilation for Chest Wall Motion Immobilization

High frequency percussive ventilation (HFPV) employs high frequency (100 to 400 bursts/min) low tidal volumes to provide respiration in awake patients while simultaneously eliminating respiratory motion. In this study, we evaluate each HFPV interface device for compliance, ease of use, comfort, geometric interference, minimal chest wall motion and prolonged percussive time. We recruited 15 healthy volunteers (age 30y-75y) and investigated three types of interfaces on an IRB approved study. The first interface was a soft plastic mouthpiece. The second interface was a silicon oral only mask with headgear straps for pressure adjustments. The third interface was a full-face mask that used gel pad with a silicon flap and CapStrap headgear for comfort. Rubber nose clips were utilized for all interfaces. The volunteers were evaluated supine on a flat treatment bed with their arms above their head. Their chest wall motion was monitored using an external respiratory motion laser system. The percussive ventilations were delivered via an air driven pneumatic system. All volunteers were monitored for PO2 and tc-CO2 with a pulse oximeter and CO2 system. After each interface device, the volunteers completed a questionnaire to provide their feedback on comfort, pain, dyspnea, anxiety etc. on a subjective rating scale ranging from one to five. The external respiratory motion signal was analyzed for length of percussive time, Duty Cycle (DC) (for 2mm and 5mm threshold band) and ripple magnitude (peak to peak) for both normal and percussive breathing. A total of N=62 percussive sessions were analyzed from the external respiratory motion laser system. Although all volunteers experienced a base-line drift in amplitude, the mean breath hold was 199.37sec (med: 115.50sec, range: 9.00sec to 16.83min). DC ranged from 14.00-100.00% (med: 52.09%, mean: 55.67%) for 2mm threshold band and 31.85-100.00% (med: 93.03%, mean: 87.24%) for 5mm. A temporal local chest wall ripple magnitude reduction was observed from mean 9.37mm (N=27, med: 9.71mm, range: 2.70-18.60mm) in normal breathing to mean 2.55mm (med: 2.29mm, range: 0.60- 6.51mm) in percussive. Most volunteers indicated that the third interface provided additional comfort and less dyspnea (mean subjective score: 4.03) compare to the other two interfaces (mean subjective score: 3.63 and 3.66 for first and second interface respectively); they were in percussive state longer with the second interface. Volunteers had an increase in percussive time by 66.61%, 63.16% and 5.65% from the total mean when using second interface vs. third and first respectively. During this study, we were able to conclude that the second interface can prolong the percussive sessions when compared to the other two. Chest-wall motion was well tolerated and drastically reduced using HFPV in each volunteer evaluated. As a result, we believe HFPV may provide thoracic immobilization during radiotherapy, particularly in the SBRT and scanning pencil beam Proton therapy setting.