INTELLiVENT®-ASV®: un assistente al posto letto

BACKGROUND

Closed-loop modes automatically adjust ventilation settings, delivering individualized ventilation over short periods of time. The objective of this randomized controlled trial was to compare safety, efficacy and workload for the health care team between IntelliVent®-ASV and conventional modes over a 48-hour period.

METHODS

ICU patients admitted with an expected duration of mechanical ventilation of more than 48 hours were randomized to IntelliVent®-ASV or conventional ventilation modes. All ventilation parameters were recorded breath-by-breath. The number of manual adjustments assesses workload for the healthcare team. Safety and efficacy were assessed by calculating the time spent within previously defined ranges of non-optimal and optimal ventilation, respectively.

RESULTS

Eighty patients were analyzed. The median values of ventilation parameters over 48 hours were similar in both groups except for PEEP (7[4] cmH2O versus 6[3] cmH2O with IntelliVent®-ASV and conventional ventilation, respectively, P=0.028) and PETCO2 (36±7 mmHg with IntelliVent®-ASV versus 40±8 mmHg with conventional ventilation, P=0.041). Safety was similar between IntelliVent®-ASV and conventional ventilation for all parameters except for PMAX, which was more often non-optimal with IntelliVent®-ASV (P=0.001). Efficacy was comparable between the 2 ventilation strategies, except for SpO2 and VT, which were more often optimal with IntelliVent®-ASV (P=0.005, P=0.016, respectively). IntelliVent®-ASV required less manual adjustments than conventional ventilation (P<0.001) for a higher total number of adjustments (P<0.001). The coefficient of variation over 48 hours was larger with IntelliVent®-ASV in regard of maximum pressure, inspiratory pressure (PINSP), and PEEP as compared to conventional ventilation.

CONCLUSIONS

IntelliVent®-ASV required less manual intervention and delivered more variable PEEP and PINSP, while delivering ventilation safe and effective ventilation in terms of VT, RR, SpO2 and PETCO2.

BACKGROUND

The discontinuation of mechanical ventilation after coronary surgery may prolong and significantly increase the load on intensive care unit personnel. We hypothesized that automated mode using INTELLiVENT-ASV can decrease duration of postoperative mechanical ventilation, reduce workload on medical staff, and provide safe ventilation after off-pump coronary artery bypass grafting (OPCAB). The primary endpoint of our study was to assess the duration of postoperative mechanical ventilation during different modes of weaning from respiratory support (RS) after OPCAB. The secondary endpoint was to assess safety of the automated weaning mode and the number of manual interventions to the ventilator settings during the weaning process in comparison with the protocolized weaning mode.

MATERIALS AND METHODS

Forty adult patients undergoing elective OPCAB were enrolled into a prospective single-center study. Patients were randomized into two groups: automated weaning (n = 20) using INTELLiVENT-ASV mode with quick-wean option; and protocolized weaning (n = 20), using conventional synchronized intermittent mandatory ventilation (SIMV) + pressure support (PS) mode. We assessed the duration of postoperative ventilation, incidence and duration of unacceptable RS, and the load on medical staff. We also performed the retrospective analysis of 102 patients (standard weaning) who were weaned from ventilator with SIMV + PS mode based on physician's experience without prearranged algorithm.

RESULTS AND DISCUSSION

Realization of the automated weaning protocol required change in respiratory settings in 2 patients vs. 7 (5-9) adjustments per patient in the protocolized weaning group. Both incidence and duration of unacceptable RS were reduced significantly by means of the automated weaning approach. The FiO2 during spontaneous breathing trials was significantly lower in the automated weaning group: 30 (30-35) vs. 40 (40-45) % in the protocolized weaning group (p < 0.01). The average time until tracheal extubation did not differ in the automated weaning and the protocolized weaning groups: 193 (115-309) and 197 (158-253) min, respectively, but increased to 290 (210-411) min in the standard weaning group.

CONCLUSION

The automated weaning system after off-pump coronary surgery might provide postoperative ventilation in a more protective way, reduces the workload on medical staff, and does not prolong the duration of weaning from ventilator. The use of automated or protocolized weaning can reduce the duration of postoperative mechanical ventilation in comparison with non-protocolized weaning based on the physician's decision.

BACKGROUND

Driving pressure (ΔP) and mechanical power (MP) are predictors of the risk of ventilation- induced lung injuries (VILI) in mechanically ventilated patients. INTELLiVENT-ASV® is a closed-loop ventilation mode that automatically adjusts respiratory rate and tidal volume, according to the patient's respiratory mechanics.

OBJECTIVES

This prospective observational study investigated ΔP and MP (and also transpulmonary ΔP (ΔPL) and MP (MPL) for a subgroup of patients) delivered by INTELLiVENT-ASV.

METHODS

Adult patients admitted to the ICU were included if they were sedated and met the criteria for a single lung condition (normal lungs, COPD, or ARDS). INTELLiVENT-ASV was used with default target settings. If PEEP was above 16 cmH2O, the recruitment strategy used transpulmonary pressure as a reference, and ΔPL and MPL were computed. Measurements were made once for each patient.

RESULTS

Of the 255 patients included, 98 patients were classified as normal-lungs, 28 as COPD, and 129 as ARDS patients. The median ΔP was 8 (7 - 10), 10 (8 - 12), and 9 (8 - 11) cmH2O for normal-lungs, COPD, and ARDS patients, respectively. The median MP was 9.1 (4.9 - 13.5), 11.8 (8.6 - 16.5), and 8.8 (5.6 - 13.8) J/min for normal-lungs, COPD, and ARDS patients, respectively. For the 19 patients managed with transpulmonary pressure ΔPL was 6 (4 - 7) cmH2O and MPL was 3.6 (3.1 - 4.4) J/min.

CONCLUSIONS

In this short term observation study, INTELLiVENT-ASV selected ΔP and MP considered in safe ranges for lung protection. In a subgroup of ARDS patients, the combination of a recruitment strategy and INTELLiVENT-ASV resulted in an apparently safe ΔPL and MPL.

BACKGROUND

Lung-protective ventilation is key in bridging patients suffering from COVID-19 acute respiratory distress syndrome (ARDS) to recovery. However, resource and personnel limitations during pandemics complicate the implementation of lung-protective protocols. Automated ventilation modes may prove decisive in these settings enabling higher degrees of lung-protective ventilation than conventional modes.

METHOD

Prospective study at a Swiss university hospital. Critically ill, mechanically ventilated COVID-19 ARDS patients were allocated, by study-blinded coordinating staff, to either closed-loop or conventional mechanical ventilation, based on mechanical ventilator availability. Primary outcome was the overall achieved percentage of lung-protective ventilation in closed-loop versus conventional mechanical ventilation, assessed minute-by-minute, during the initial 7 days and overall mechanical ventilation time. Lung-protective ventilation was defined as the combined target of tidal volume <8 ml per kg of ideal body weight, dynamic driving pressure <15 cmH2O, peak pressure <30 cmH2O, peripheral oxygen saturation ≥88% and dynamic mechanical power <17 J/min.

RESULTS

Forty COVID-19 ARDS patients, accounting for 1,048,630 minutes (728 days) of cumulative mechanical ventilation, allocated to either closed-loop (n = 23) or conventional ventilation (n = 17), presenting with a median paO2/ FiO2 ratio of 92 [72-147] mmHg and a static compliance of 18 [11-25] ml/cmH2O, were mechanically ventilated for 11 [4-25] days and had a 28-day mortality rate of 20%. During the initial 7 days of mechanical ventilation, patients in the closed-loop group were ventilated lung-protectively for 65% of the time versus 38% in the conventional group (Odds Ratio, 1.79; 95% CI, 1.76-1.82; P < 0.001) and for 45% versus 33% of overall mechanical ventilation time (Odds Ratio, 1.22; 95% CI, 1.21-1.23; P < 0.001).

CONCLUSION

Among critically ill, mechanically ventilated COVID-19 ARDS patients during an early highpoint of the pandemic, mechanical ventilation using a closed-loop mode was associated with a higher degree of lung-protective ventilation than was conventional mechanical ventilation.

PURPOSE

Our aim was to compare adaptive support ventilation with and without closed loop control by end tidal CO2 (ASVCO2, ASV) with pressure (PC) and volume control ventilation (VC) during simulated clinical scenarios [normal lungs (N), COPD, ARDS, brain injury (BI)].

METHODS

A lung model was used to simulate representative compliance (mL/cmH2O): resistance (cmH2O/L/s) combinations, 45:5 for N and BI, 60:7.7 for COPD, 15:7.7 and 35:7.7 for ARDS. Two levels of PEEP (cmH2O) were used for each scenario, 12/16 for ARDS, and 5/10 for others. The CO2 productions of 2, 3, 4 and 5 mL/kg predicted body weight/min were simulated. Tidal volume was set to 6 mL/kg during VC and PC. Outcomes of interest were end tidal CO2 (etCO2) and plateau pressure (P Plat).

RESULTS

EtCO2 levels in N and BI and COPD were similar for all modes. In ARDS, etCO2 was higher in ASVCO2 than in other modes (p < 0.001). Under all mechanical conditions ASVCO2 revealed a narrower range of etCO2. P Plat was similar for all modes in all scenarios but ARDS where P Plat in ASV and ASVCO2 were lower than in VC (p = 0.001). When P Plat was ≥ 28 cmH2O, P plat in ASV and ASVCO2 were lower than in VC and PC (p = 0.024).

CONCLUSION

All modes performed similarly in most cases. Minor differences observed were in favor of the closed loop modes. Overall, ASVCO2 maintained tighter CO2 control. The ASVCO2 had the greatest impact during ARDS allowing etCO2 to increase and protecting against hypocapnia evident with other modes while ensuring lower P plat and tidal volumes.

PURPOSE

Discrepancies between the demand and availability of clinicians to care for mechanically ventilated patients can be anticipated due to an aging population and to increasing severity of illness. The use of closed-loop ventilation provides a potential solution. The aim of the study was to evaluate the safety of a fully automated ventilator.

METHODS

We conducted a randomized controlled trial comparing automated ventilation (AV) and protocolized ventilation (PV) in 60 ICU patients after cardiac surgery. In the PV group, tidal volume, respiratory rate, FiO(2) and positive end-expiratory pressure (PEEP) were set according to the local hospital protocol based on currently available guidelines. In the AV group, only sex, patient height and a maximum PEEP level of 10 cmH(2)O were set. The primary endpoint was the duration of ventilation within a "not acceptable" range of tidal volume. Zones of optimal, acceptable and not acceptable ventilation were based on several respiratory parameters and defined a priori.

RESULTS

The patients were assigned equally to each group, 30 to PV and 30 to AV. The percentage of time within the predefined zones of optimal, acceptable and not acceptable ventilation were 12 %, 81 %, and 7 % respectively with PV, and 89.5 %, 10 % and 0.5 % with AV (P < 0.001). There were 148 interventions required during PV compared to only 5 interventions with AV (P < 0.001).

CONCLUSION

Fully AV was safe in hemodynamically stable patients immediately following cardiac surgery. In addition to a reduction in the number of interventions, the AV system maintained patients within a predefined target range of optimal ventilation.