Adaptive Support Ventilation Group Research Articles

Adaptive Support Ventilation and Lung-Protective Ventilation in ARDS.

Adaptive support ventilation (ASV) is a partially closed-loop ventilation mode that adjusts tidal volume (VT) and breathing frequency (f) to minimize mechanical work and driving pressure. ASV is routinely used but has not been widely studied in ARDS. The study was a crossover study with randomization to intervention comparing a pressure-regulated, volume-targeted ventilation mode (adaptive pressure ventilation [APV], standard of care at Beth Israel Deaconess Medical Center) set to VT 6 mL/kg in comparison with ASV mode where VT adjustment is automated. Subjects received standard of care (APV) or ASV and then crossed over to the alternate mode, maintaining consistent minute ventilation with 1-2 h in each mode. The primary outcome was VT corrected for ideal body weight (IBW) before and after crossover. Secondary outcomes included driving pressure, mechanics, gas exchange, mechanical power, and other parameters measured after crossover and longitudinally. Twenty subjects with ARDS were consented, with 17 randomized and completing the study (median PaO2 /FIO2 146.6 [128.3-204.8] mm Hg) and were mostly passive without spontaneous breathing. ASV mode produced marginally larger VT corrected for IBW (6.3 [5.9-7.0] mL/kg IBW vs 6.04 [6.0-6.1] mL/kg IBW, P = .035). Frequency was lower with patients in ASV mode (25 [22-26] breaths/min vs 27 [22-30)] breaths/min, P = .01). In ASV, lower respiratory-system compliance correlated with smaller delivered VT/IBW (R2 = 0.4936, P = .002). Plateau (24.7 [22.6-27.6] cm H2O vs 25.3 [23.5-26.8] cm H2O, P = .14) and driving pressures (12.8 [9.0-15.8] cm H2O vs 11.7 [10.7-15.1] cm H2O, P = .29) were comparable between conventional ventilation and ASV. No adverse events were noted in either ASV or conventional group related to mode of ventilation. ASV targeted similar settings as standard of care consistent with lung-protective ventilation strategies in mostly passive subjects with ARDS. ASV delivered VT based upon respiratory mechanics, with lower VT and mechanical power in subjects with stiffer lungs.

Comparison of adaptive support ventilation and synchronized intermittent mandatory ventilation in patients with acute respiratory distress syndrome: A randomized clinical trial

Background:Suitable mechanical ventilation strategies can reduce the incidence and severity of ventilator-associated lung injury in patients with acute respiratory distress syndrome (ARDS). In this study, the effects of adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) on respiratory parameters and arterial blood gases (ABGs) parameters were compared in ARDS patients.Materials and Methods:Twenty-four patients were randomly divided into two groups of ASV and SIMV. Patients were followed up for 3 days, and respiratory parameters including rapid shallow breathing index (RSBI), spontaneous breathing rate (SBR), minute volume, and peak inspiratory pressure (PIP) as the primary outcomes and ABG parameters including PaO2, FiO2, PaCO2, HCO3, and PaO2/FiO2 ratio as the secondary outcomes were measured.Results:PIP in patients in the SIMV group on the 1st day (P = 0.013), 2nd day (P = 0.001), and 3rd day (P = 0.004) was statistically significantly more compared to those in patients in the ASV group. RSBI, SBR, and minute volume between the ASV and SIMV groups during the 3 days were not statistically significantly different (P > 0.05). The mean arterial blood pressure, heart rate, PaO2, and PH between both groups were similar (P > 0.05). At the end of the 2nd and 3rd days, the level of FiO2 and PaCO2 in ASV was significantly lower than those in ASV group. HCO3 in each of the 3 days in the ASV group was statistically significantly lower than that in the SIMV group (P < 0.050). PaO2/FiO2 ratio in patients in the ASV group in the 3 days was statistically significantly higher than that in the SIMV group (P < 0.050).Conclusion:By reducing PIP and improving oxygenation and ABG parameters, ASV mode may be a safe and feasible mode during mechanical ventilation in patients with ARDS.

Automated mechanical ventilation using Adaptive Support Ventilation versus conventional ventilation including ventilator length of stay, mortality, and professional social aspects of adoption of new technology.

Background Automation of mechanical ventilation allows for reduction of variation in patient management and has the potential to provide increased patient safety by strict adherence to computer driven ventilator protocols. Methods: A retrospective, observational study compared a group of 196 of general ICU patients managed exclusively on automated mechanical ventilation, adaptive support ventilation (ASV), to another group of 684 managed by usual, non-automated mechanical ventilation (No ASV). The data was collected in a unique access database designed to collect data for assessment of mechanical ventilation outcomes in a small medical center ICU. Results: The length of ventilator stay was non-significant between both groups, (81.7 ± 35.2 hours) in the ASV group; vs. (94.1 ± 35.1 hours) in the No ASV. Percent mortality was significantly less in the ASV group, 8.6% compared to 27.3% in the No ASV. Conclusion: Automated ventilation appears to be a safe ventilator strategy; however, cause effect relationships cannot be determined without further, more sophisticated studies. Keywords: Closed loop ventilation, ASV, Ventilator length of stay, Percent minute ventilation

Adaptive support ventilation attenuates postpneumonectomy acute lung injury in a porcine model.

An optimal ventilation strategy that causes as little mechanical stress and inflammation as possible is critical for patients undergoing pneumonectomy. The aim of this study was to determine whether adaptive support ventilation (ASV) can provide protective ventilation to the remaining lung after pneumonectomy with minimal mechanical stress and less inflammation than volume-control ventilation (VCV). In this study, 15 pigs were randomly allocated to 3 groups (n = 5 for each group): the control group, the VCV group and the ASV group. After left pneumonectomy, the VCV group was treated with the volume-control set to 20 ml/kg, and the ASV group with the mode set to achieve 60% of the minute ventilation of 2 lungs. The ASV group had lower alveolar strain than the VCV group. The ASV group exhibited less lung injury and greater alveolar fluid clearance than the VCV group (13.3% vs -17.8%; P ≤ 0.018). Ventilator-induced lung injury was associated with changes in the cytokine levels in the exhaled breath condensate, differential changes in plasma and changes in the cytokines in the bronchoalveolar lavage fluid. Expression of 3 microRNAs (miR449b-3p, P ≤ 0.001; miR451-5p, P = 0.027; and miR144-5p, P = 0.008) was increased in the VCV group compared with the ASV group. The ASV mode was capable of supporting rapid, shallow breathing patterns to exert lung-protective effects in a porcine postpneumonectomy model. Further investigation of microRNAs as biomarkers of ventilator-induced lung injury is warranted.

Adaptive Support Ventilation Attenuates Ventilator Induced Lung Injury: Human and Animal Study.

Adaptive support ventilation (ASV) is a closed-loop ventilation, which can make automatic adjustments in tidal volume (VT) and respiratory rate based on the minimal work of breathing. The purpose of this research was to study whether ASV can provide a protective ventilation pattern to decrease the risk of ventilator-induced lung injury in patients of acute respiratory distress syndrome (ARDS). In the clinical study, 15 ARDS patients were randomly allocated to an ASV group or a pressure-control ventilation (PCV) group. There was no significant difference in the mortality rate and respiratory parameters between these two groups, suggesting the feasible use of ASV in ARDS. In animal experiments of 18 piglets, the ASV group had a lower alveolar strain compared with the volume-control ventilation (VCV) group. The ASV group exhibited less lung injury and greater alveolar fluid clearance compared with the VCV group. Tissue analysis showed lower expression of matrix metalloproteinase 9 and higher expression of claudin-4 and occludin in the ASV group than in the VCV group. In conclusion, the ASV mode is capable of providing ventilation pattern fitting into the lung-protecting strategy; this study suggests that ASV mode may effectively reduce the risk or severity of ventilator-associated lung injury in animal models.

Weaning of chronic obstructive pulmonary disease patients after coronary artery bypass graft surgery

Background Cardiac surgery has become more common in chronic obstructive pulmonary disease (COPD) patients, but this category is still at a high risk of postoperative prolonged ventilation. Finding of the appropriate mode for faster weaning is important to improve a patient’s outcome. Objective This study aimed to evaluate the effect of adaptive support ventilation (ASV) as a weaning mode in comparison with the pressure support mode in COPD patients in the postoperative period after a coronary artery bypass grafting (CABG) surgery. Patients and methods A randomized-controlled trial was conducted on 90 COPD (stage I and II) patients between 40 and 65 years old in the postoperative cardiothoracic ICU after CABG surgeries. Patients were initially ventilated with synchronized intermittent mandatory ventilation and were then allocated randomly to two equal groups to wean either by ASV group or pressure support ventilation group. The primary outcome was the number of patients weaned successfully from the first trial. The secondary outcomes were duration of mechanical ventilation, duration of weaning, number of arterial blood gas samples before extubation, length of ICU stay, cardiac and respiratory parameters at extubation, and mortality. Result In the ASV group, significantly higher numbers of patients were weaned from first trial, there was a shorter duration of weaning and mechanical ventilation and ICU stay, with fewer times of manual ventilator adjustments and arterial blood gas samples drawing during weaning. At extubation, this group showed a significantly lower respiratory rate, higher tidal volume, and lower peak airway pressure, with less tachycardia and lower systolic blood pressure compared with the pressure support ventilation group. Conclusion The ASV mode improves the quality of weaning and shortens ICU stay in COPD patients after CABG surgery.

Adaptive support ventilation versus synchronized intermittent mandatory ventilation in patients with chronic obstructive pulmonary disease

Adaptive support ventilation (ASV) is a fully automated closed-loop ventilation mode that can act as pressure support (PS) and pressure-controlled ventilation. The aim of this study was to evaluate the benefits of using ASV in the initiation, maintenance, and weaning phases of the mechanical ventilation in comparison with synchronized intermittent mandatory ventilation (SIMV)+PS mode in patients with chronic obstructive pulmonary disease (COPD). Sixty patients with COPD requiring mechanical ventilation were recruited in this study. Among them, 37 patients were treated by SIMV+PS, whereas 23 patients were assigned for ASV. After resolution of the cause of acute respiratory failure, assessment of readiness for weaning was done. Patients were followed after 30, 60 min, and 24 h. Ventilator and hospital outcomes were recorded. Compared with SIMV+PS, ASV provided shorter weaning time (27.3 ± 12.3 vs. 62 ± 14.1 h). Moreover, there was a shorter hospital stay of 14.83 ± 6.14 for ASV group compared with 22.14 ± 17.39 days for SIMV+PS, with similar weaning failure rates, death rate, and intubation period in both groups. This study proved that ASV mode was successful as a mode of initiation, maintenance, and weaning in acute exacerbation of patients with COPD requiring mechanical ventilation with a shorter weaning time and shorter hospital stay compared with SIMV+PS mode.

Comparing the effects of adaptive support ventilation and synchronized intermittent mandatory ventilation on intubation duration and hospital stay after coronary artery bypass graft surgery.

Background:Different modes of mechanical ventilation are used for respiratory support after coronary artery bypass graft (CABG). This study aimed to compare the effect(s) of using adaptive support ventilation (ASV) and synchronized intermittent mandatory ventilation (SIMV) on the length of mechanical ventilation (intubation duration) and hospital stay after coronary artery bypass graft surgery.Materials and Methods:In a randomized control trial, 64 patients were ventilated with ASV as the experiment group or with SIMV as the control group after CABG surgery in Chamran Hospital of Isfahan University of Medical Sciences. The time of tracheal intubation and the length of hospital stay were compared between the two groups. Data were analyzed and described using statistical analysis (independent t-test).Results:The mean time of intubation duration was significantly lower in ASV group compared with SIMV group. (4.83 h vs 6.71 h, P < 0.001). The lengths of hospital stay in the ASV and the SIMV groups were 140.6 h and 145.1 h, respectively. This difference was significant between the two groups (P = 0.006).Conclusions:According to the results of this study, using ASV mode for mechanical ventilation after CABG led to a decrease in intubation duration and also hospital stay in comparison with the SIMV group. It is recommended to use ASV mode on ventilators for respiratory support of patients undergoing coronary artery bypass graft surgery.

A Randomized Controlled Trial Comparing the Ventilation Duration Between Adaptive Support Ventilation and Pressure Assist/Control Ventilation in Medical Patients in the ICU

Adaptive support ventilation (ASV) is a closed loop mode of mechanical ventilation (MV) that provides a target minute ventilation by automatically adapting inspiratory pressure and respiratory rate with the minimum work of breathing on the part of the patient. The aim of this study was to determine the effect of ASV on total MV duration when compared with pressure assist/control ventilation. Adult medical patients intubated and mechanically ventilated for > 24 h in a medical ICU were randomized to either ASV or pressure assist/control ventilation. Sedation and medical treatment were standardized for each group. Primary outcome was the total MV duration. Secondary outcomes were the weaning duration, number of manual settings of the ventilator, and weaning success rates. Two hundred twenty-nine patients were included. Median MV duration until weaning, weaning duration, and total MV duration were significantly shorter in the ASV group (67 [43-94] h vs 92 [61-165] h, P = .003; 2 [2-2] h vs 2 [2-80] h, P = .001; and 4 [2-6] days vs 4 [3-9] days, P = .016, respectively). Patients in the ASV group required fewer total number of manual settings on the ventilator to reach the desired pH and Paco2 levels (2 [1-2] vs 3 [2-5], P < .001). The number of patients extubated successfully on the first attempt was significantly higher in the ASV group (P = .001). Weaning success and mortality at day 28 were comparable between the two groups. In medical patients in the ICU, ASV may shorten the duration of weaning and total MV duration with a fewer number of manual ventilator settings. ClinicalTrials.gov; No.: NCT01472302; URL: www.clinicaltrials.gov.

A randomized controlled trial of adaptive support ventilation mode to wean patients after fast-track cardiac valvular surgery.

Adaptive support ventilation can speed weaning after coronary artery surgery compared with protocolized weaning using other modes. There are no data to support this mode of weaning after cardiac valvular surgery. Furthermore, control group weaning times have been long, suggesting that the results may reflect control group protocols that delay weaning rather than a real advantage of adaptive support ventilation. Randomized (computer-generated sequence and sealed opaque envelopes), parallel-arm, unblinded trial of adaptive support ventilation versus physician-directed weaning after adult fast-track cardiac valvular surgery. The primary outcome was duration of mechanical ventilation. Patients aged 18 to 80 yr without significant renal, liver, or lung disease or severe impairment of left ventricular function undergoing uncomplicated elective valve surgery were eligible. Care was standardized, except postoperative ventilation. In the adaptive support ventilation group, target minute ventilation and inspired oxygen concentration were adjusted according to blood gases. A spontaneous breathing trial was carried out when the total inspiratory pressure of 15 cm H2O or less with positive end-expiratory pressure of 5 cm H2O. In the control group, the duty physician made all ventilatory decisions. Median duration of ventilation was statistically significantly shorter (P = 0.013) in the adaptive support ventilation group (205 [141 to 295] min, n = 30) than that in controls (342 [214 to 491] min, n = 31). Manual ventilator changes and alarms were less common in the adaptive support ventilation group, and arterial blood gas estimations were more common. Adaptive support ventilation reduces ventilation time by more than 2 h in patients who have undergone fast-track cardiac valvular surgery while reducing the number of manual ventilator changes and alarms.

Adaptive support ventilation versus biphasic positive airway pressure in patients with acute exacerbation of chronic obstructive pulmonary disease

Introduction The goal of mechanical ventilation in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is to maintain both adequate oxygenation and ventilation, reduce the work of breathing, and improve the comfort of the patient until the condition has been reversed or alleviated. Unlike conventional pressure-controlled ventilatory modes, biphasic modes [biphasic positive airway pressure (BIPAP)] allow for unrestricted spontaneous breathing. Adaptive support ventilation (ASV) is a new ventilatory mode that uses a closed-loop controlled mode between breaths. It can be used safely during initiation, maintenance, or weaning phases of the mechanical ventilation. Objective The aim of this work was to compare between BIPAP and ASV in the management of patients with AECOPD in terms of ventilatory parameters, lung mechanics, patient ventilator dys-synchrony, days of mechanical ventilation, and mortality. Patients and methods This double-blind randomized trial was conducted on 72 AECOPD adult patients admitted to the units of Critical Care Medicine Department in Alexandria Main University Hospital indicated for invasive mechanical ventilation. Patients were excluded for reasons such as pregnancy, hemodynamic instability, and severe neurological disease. They were categorized randomly as follows: group I included 36 patients who were ventilated using the BIPAP mode and group II included 36 patients who were ventilated using the ASV mode. Informed consent was obtained from patients' first of kin after approval from the Ethical Committee of Alexandria Faculty of Medicine. Ventilatory parameters (respiratory rate, tidal volume, peak airway pressure, and rapid shallow breathing index) and lung mechanics (static compliance and inspiratory resistance) were recorded. Patient ventilator dys-synchrony and asynchrony index were recorded daily. Days of mechanical ventilation, ICU stay, and mortality were calculated. Results In the ASV group, the respiratory rate was significantly lower, tidal volume was higher, and rapid shallow breathing index was lower. Significantly higher compliance and lower resistance were encountered in the ASV group, with better patient-ventilator synchronization. A significant reduction in days of mechanical ventilation in the ASV group was found with less ICU length of stay. Conclusion ASV may be safer in AECOPD patients and may have a better prognosis.

Adaptive Support Ventilation Versus Synchronized Intermittent Mandatory Ventilation With Pressure Support in Weaning Patients After Orthotopic Liver Transplantation

BackgroundThe extubation phase is an extremely critical moment in patients who have undergone orthotopic liver transplantation, who do not always have the advantage of long-lasting positive-pressure ventilation and positive expiratory end pressure; these factors can lead to splanchnic venous congestion, and this is why a rapid extubation can represent a great benefit for the graft. MethodsThe aim of this study was to compare the adaptive support ventilation (ASV) mode with the standard mode of weaning in our intensive care unit, synchronized intermittent mandatory ventilation with pressure support (P-SIMV), in patients who received orthotopic liver transplantation. ASV is a positive-pressure mode, in which pressure level and respiratory rate are automatically adjusted according to measured lung dynamics at each breath. Eligible patients were assigned to either ASV or P-SIMV group. The weaning protocol was based on the individual respiratory activity and structured in 4 different phases. ResultsThe average length of intubation was significantly shorter in the ASV group than in the P-SIMV group (90 ± 13 vs 153 ± 22 minutes, P = .05). The total modifications to the ventilator settings were significantly larger in the P-SIMV group (1.5 ± 1 vs 6 ± 2; P = .003). ConclusionsOur results suggest that although both procedures are safe and easy to apply, ASV is superior in terms of weaning times, and it simplifies respiratory management. The better patient-machine interaction in ASV has been highlighted by other authors for different clusters of patients.

Effects of Implementing Adaptive Support Ventilation in a Medical Intensive Care Unit

Adaptive support ventilation (ASV) facilitates ventilator liberation in postoperative patients in surgical intensive care units (ICU). Whether ASV has similar benefits in patients with acute respiratory failure is unclear. We conducted a pilot study in a medical ICU that manages approximately 600 mechanically ventilated patients a year. The ICU has one respiratory therapist who manages ventilators twice during the day shift (8:00 am to 5:00 pm). No on-site respiratory therapist was present at night. We prospectively enrolled 79 patients mechanically ventilated for ≥ 24 hours on pressure support of ≥ 15 cm H(2)O, with or without synchronized intermittent mandatory ventilation, F(IO(2)) ≤ 50%, and PEEP ≤ 8 cm H(2)O. We switched the ventilation mode to ASV starting at a "%MinVol" setting of 80-100%. We defined spontaneous breathing trial (SBT) readiness as a frequency/tidal-volume ratio of < 105 (breaths/min)/L on pressure support of ≤ 8 cm H(2)O and PEEP of ≤ 5 cm H(2)O for at least 2 h, and all spontaneous breaths. The T-piece SBT was considered successful if the frequency/tidal-volume ratio remained below 105 (breaths/min)/L for 30 min, and we extubated after successful SBT. The control group consisted of 70 patients managed with conventional ventilation modes and a ventilator protocol during a 6-month period immediately before the ASV study period. Extubation was attempted in 73% of the patients in the ASV group, and 80% of the patients in the non-ASV group. The re-intubation rates in the ASV and non-ASV groups were 5% and 7%, respectively. In the ASV group, 20% of the patients achieved extubation readiness within 1 day, compared to 4% in the non-ASV group (P = <.001). The median time from the enrollment to extubation readiness was 1 day for the ASV group and 3 days for the non-ASV group (P = .055). Patients switched to ASV were more likely to be liberated from mechanical ventilation at 3 weeks (P = .04). Multiple logistic regression analysis showed that, of the independent factors in the model, only ASV was associated with shorter time to extubation readiness (P = .048 via likelihood ratio test). Extubation readiness may not be recognized in a timely manner in at least 15% of patients recovering from respiratory failure. ASV helps to identify these patients and may improve their weaning outcomes.

Adaptive Support Ventilation Prevents Ventilator-induced Diaphragmatic Dysfunction in Piglet

Contrary to adaptive support ventilation (ASV), prolonged totally controlled mechanical ventilation (CMV) results in the absence of diaphragm activity and causes ventilator-induced diaphragmatic dysfunction. Because maintaining respiratory muscles at rest is likely a major cause of ventilator-induced diaphragmatic dysfunction, ASV may prevent its occurrence in comparison with CMV. The aim of our study was to compare the effects of ASV with those of CMV on both in vivo and in vitro diaphragmatic properties. Two groups of six anesthetized piglets were ventilated during a 72-h period. Piglets in the CMV group (n = 6) were ventilated without spontaneous ventilation, and piglets in the ASV group (n = 6) were ventilated with spontaneous breaths. Transdiaphragmatic pressure was measured after bilateral, supramaximal transjugular stimulation of the two phrenic nerves. A pressure-frequency curve was drawn after stimulation from 20 to 120 Hz of the phrenic nerves. Diaphragm fiber proportions and mean sectional area were evaluated. After 72 h of ventilation, transdiaphragmatic pressure decreased by 30% of its baseline value in the CMV group, whereas it did not decrease in the ASV group. Although CMV was associated with an atrophy of the diaphragm (evaluated by mean cross-sectional area of both the slow and fast myosin chains), atrophy was not detected in the ASV group. Maintaining diaphragmatic contractile activity by using the ASV mode may protect the diaphragm against the deleterious effect of prolonged CMV, as demonstrated both in vitro and in vivo, in healthy piglets.

Weaning Automation with Adaptive Support Ventilation: A Randomized Controlled Trial in Cardiothoracic Surgery Patients

Adaptive support ventilation (ASV) is a microprocessor-controlled mode of mechanical ventilation that switches automatically from controlled ventilation to assisted ventilation and selects ventilatory settings according to measured lung mechanics. In a randomized controlled trial, non-fast-track coronary artery bypass grafting patients' lungs were ventilated with ASV or pressure-controlled/pressure-support ventilation (control) to compare time until tracheal extubation, duration of controlled ventilation versus assisted ventilation, and ventilation characteristics. One hundred twenty-eight consecutive patients were randomized. ASV patients had their tracheas extubated after median 16.4 and interquartile range 12.5-20.8 hr, and control patients after 16.3 (13.7-19.3) hr, respectively (P = 0.97). The percentage of time patients were on assisted ventilation (expressed as the median percentage of total duration of ventilation) was 43% (28%-67%) in the ASV group and 52% (33%-75%) in the control group (P < 0.05). However, the number of switches from controlled to assisted ventilation was higher in the ASV group (43.0 [14.0-74.0]) than in the control group (4.0 [2.0-9.0]) (P < 0.001). In ASV patients, mean tidal volumes were significantly larger during controlled ventilation than in control patients (8.6 +/- 0.8 mL/kg predicted body weight vs 7.1 +/- 1.4 mL/kg predicted body weight; P = 0.05), and no differences in tidal volumes were found during assisted ventilation. Weaning automation with ASV is feasible and safe in non-fast-track coronary artery bypass grafting patients. Time until tracheal extubation with ASV equals time until tracheal extubation with standard weaning and allows for frequent (automatic) switches between controlled and assisted ventilation.