Individualized flow-controlled ventilation compared to best clinical practice pressure-controlled ventilation: a prospective randomized porcine study

Sex related differences in applied tidal volume with flow-controlled ventilation: a subgroup analysis

BACKGROUND

Flow-controlled ventilation (FCV) ensures a constant gas flow whereby precise determination of dynamic compliance is feasible. Accordingly, ventilator pressure settings can be adjusted to achieve the highest compliance. This setting will automatically adapt tidal volume to the functionally available lung volume as a personalized approach. This is in contrast to current ventilation settings, where fixed tidal volumes according to predicted body weight (PBW) are recommended. Aim of this subgroup-analysis was to determine whether applied tidal volume differs in male and female patients after compliance guided individualization of ventilation parameters.

METHODS

A sub-group analysis of 24 patients randomized to receive flow-controlled ventilation in cardiac surgery was performed. Linear mixed-effects model was used in order to investigate sex related differences in respiratory parameters.

RESULTS

Compliance guided pressure titration led to comparable pressure settings in male (N.=18) and female (N.=6) patients. In contrast, the applied tidal volume was significantly lower in female patients (8.6 vs. 9.9, 95% CI: -2.3 to -0.2 mL/kg PBW; P=0.029) compared to male individuals, due to a significantly lower compliance (49.3 vs. 70.3, 95% CI: -33.1 to -8.8 mL/cmH2O; P=0.003). Gas exchange parameters were comparable in either sex.

CONCLUSIONS

Female patients were found to receive lower tidal volumes after compliance guided individualization compared to men during cardiac surgery. This finding may indicate that the functionally available lung volume in women is lower and thus using PBW may not adequately comply with sex related differences, which supports the use of a personalized ventilation strategy.

Individualised flow-controlled ventilation reduces applied mechanical power and improves ventilation efficiency in a porcine intra-abdominal hypertension model

BACKGROUND

Aim of this study was to evaluate feasibility and effects of individualised flow-controlled ventilation (FCV), based on compliance guided pressure settings, compared to standard of pressure-controlled ventilation (PCV) in a porcine intra-abdominal hypertension (IAH) model. The primary aim of this study was to investigate oxygenation. Secondary aims were to assess respiratory and metabolic variables and lung tissue aeration.

METHODS

Pigs were randomly assigned to FCV (n = 9) and PCV (n = 9). IAH was induced by insufflation of air into the abdomen to induce IAH grades ranging from 0 to 3. At each IAH grade FCV was undertaken using compliance guided pressure settings, or PCV (n = 9) was undertaken with the positive end-expiratory pressure titrated for maximum compliance and the peak pressure set to achieve a tidal volume of 7 ml/kg. Gas exchange, ventilator settings and derived formulas were recorded at two timepoints for each grade of IAH. Lung aeration was assessed by a computed tomography scan at IAH grade 3.

RESULTS

All 18 pigs (median weight 54 kg [IQR 51-67]) completed the observation period of 4 h. Oxygenation was comparable at each IAH grade, but a significantly lower minute volume was required to secure normocapnia in FCV at all IAH grades (7.6 vs. 14.4, MD - 6.8 (95% CI - 8.5 to - 5.2) l/min; p < 0.001). There was also a significant reduction of applied mechanical power being most evident at IAH grade 3 (25.9 vs. 57.6, MD - 31.7 (95% CI - 39.7 to - 23.7) J/min; p < 0.001). Analysis of Hounsfield unit distribution of the computed tomography scans revealed a significant reduction in non- (5 vs. 8, MD - 3 (95% CI - 6 to 0) %; p = 0.032) and poorly-aerated lung tissue (7 vs. 15, MD - 6 (95% CI - 13 to - 3) %, p = 0.002) for FCV. Concomitantly, normally-aerated lung tissue was significantly increased (84 vs. 76, MD 8 (95% CI 2 to 15) %; p = 0.011).

CONCLUSIONS

Individualised FCV showed similar oxygenation but required a significantly lower minute volume for CO2-removal, which led to a remarkable reduction of applied mechanical power. Additionally, there was a shift from non- and poorly-aerated lung tissue to normally-aerated lung tissue in FCV compared to PCV.

Flow-controlled versus pressure-controlled ventilation in cardiac surgery with cardiopulmonary bypass - A single-center, prospective, randomized, controlled trial

STUDY OBJECTIVE

Multifactorial comparison of flow-controlled ventilation (FCV) to standard of pressure-controlled ventilation (PCV) in terms of oxygenation in cardiac surgery patients after chest closure.

DESIGN

Prospective, non-blinded, randomized, controlled trial.

SETTING

Operating theatre at an university hospital, Austria.

PATIENTS

Patients scheduled for elective, open, on-pump, cardiac surgery.

INTERVENTIONS

Participants were randomized to either individualized FCV (compliance guided end-expiratory and peak pressure setting) or control of PCV (compliance guided end-expiratory pressure setting and tidal volume of 6-8 ml/kg) for the duration of surgery.

MEASUREMENTS

The primary outcome measure was oxygenation (PaO2/FiO2) 15 min after intraoperative chest closure. Secondary endpoints included CO2-removal assessed as required minute volume to achieve normocapnia and lung tissue aeration assessed by Hounsfield unit distribution in postoperative computed tomography scans.

MAIN RESULTS

Between April 2020 and April 2021 56 patients were enrolled and 50 included in the primary analysis (mean age 70 years, 38 (76%) men). Oxygenation, assessed by PaO2/FiO2, was significantly higher in the FCV group (n = 24) compared to the control group (PCV, n = 26) (356 vs. 309, median difference (MD) 46 (95% CI 3 to 90) mmHg; p = 0.038). Additionally, the minute volume required to obtain normocapnia was significantly lower in the FCV group (4.0 vs. 6.1, MD -2.0 (95% CI -2.5 to -1.5) l/min; p < 0.001) and correlated with a significantly lower exposure to mechanical power (5.1 vs. 9.8, MD -5.1 (95% CI -6.2 to -4.0) J/min; p < 0.001). Evaluation of lung tissue aeration revealed a significantly reduced amount of non-aerated lung tissue in FCV compared to PCV (5 vs. 7, MD -3 (95% CI -4 to -1) %; p < 0.001).

CONCLUSIONS

In patients undergoing on-pump, cardiac surgery individualized FCV significantly improved oxygenation and lung tissue aeration compared to PCV. In addition, carbon dioxide removal was accomplished at a lower minute volume leading to reduced applied mechanical power.

Understanding the mechanisms of ventilator-induced lung injury using animal models

Mechanical ventilation is a life-saving therapy in several clinical situations, promoting gas exchange and providing rest to the respiratory muscles. However, mechanical ventilation may cause hemodynamic instability and pulmonary structural damage, which is known as ventilator-induced lung injury (VILI). The four main injury mechanisms associated with VILI are as follows: barotrauma/volutrauma caused by overstretching the lung tissues; atelectrauma, caused by repeated opening and closing of the alveoli resulting in shear stress; and biotrauma, the resulting biological response to tissue damage, which leads to lung and multi-organ failure. This narrative review elucidates the mechanisms underlying the pathogenesis, progression, and resolution of VILI and discusses the strategies that can mitigate VILI. Different static variables (peak, plateau, and driving pressures, positive end-expiratory pressure, and tidal volume) and dynamic variables (respiratory rate, airflow amplitude, and inspiratory time fraction) can contribute to VILI. Moreover, the potential for lung injury depends on tissue vulnerability, mechanical power (energy applied per unit of time), and the duration of that exposure. According to the current evidence based on models of acute respiratory distress syndrome and VILI, the following strategies are proposed to provide lung protection: keep the lungs partially collapsed (SaO2 > 88%), avoid opening and closing of collapsed alveoli, and gently ventilate aerated regions while keeping collapsed and consolidated areas at rest. Additional mechanisms, such as subject-ventilator asynchrony, cumulative power, and intensity, as well as the damaging threshold (stress-strain level at which tidal damage is initiated), are under experimental investigation and may enhance the understanding of VILI.

Perioperative lung function following flow controlled ventilation for robot-assisted prostatectomies in steep trendelenburg position: an observational study

BACKGROUND

Steep Trendelenburg position combined with capnoperitoneum can lead to pulmonary complications and prolonged affection of postoperative lung function. Changes in pulmonary function occur independent of different modes of ventilation and levels of positive end-expiratory pressure (PEEP). The effect of flow-controlled ventilation (FCV) has not been evaluated yet. We perioperatively measured spirometric lung function parameters in patients undergoing robot-assisted prostatectomy under FCV. Our primary hypothesis was that there is no significant difference in the ratio of the maximal mid expiratory and inspiratory flow (MEF50/MIF50) after surgery.

METHODS

In 20 patients, spirometric measurements were obtained preoperatively, 40, 120, and 240 min and 1 and 5 days postoperatively. We measured MEF50/MIF50, vital capacity (VC), forced expiratory volume in 1 s (FEV1), and intraoperative ventilation parameters.

RESULTS

MEF50/MIF50 ratio increased from 0.92 (CI 0.73-1.11) to 1.38 (CI 1.01-1.75, p < 0.0001) and returned to baseline within 24 h, while VC and FEV1 decreased postoperatively with a second nadir at 24 h and only normalized by the fifth day (p < 0.0001). Compared to patients with PCV, postoperative lung function changes similarly.

CONCLUSION

Flow-controlled ventilation led to changes in lung function similar to those observed with pressure-controlled ventilation. While the ratio of MEF50/MIF50 normalized within 24 h, VC and FEV1 recovered within 5 days after surgery.

Individualised flow-controlled versus pressure-controlled ventilation in a porcine oleic acid-induced acute respiratory distress syndrome model

BACKGROUND

A continuous gas flow provided by flow-controlled ventilation (FCV) facilitates accurate dynamic compliance measurement and allows the clinician to individually optimise positive end-expiratory and peak pressure settings accordingly.

OBJECTIVE

The aim of this study was to compare the efficiency of gas exchange and impact on haemodynamics between individualised FCV and pressure-controlled ventilation (PCV) in a porcine model of oleic acid-induced acute respiratory distress syndrome (ARDS).

DESIGN

Randomised controlled interventional trial conducted on 16 pigs.

SETTING

Animal operating facility at the Medical University Innsbruck.

INTERVENTIONS

ARDS was induced in lung healthy pigs by intravenous infusion of oleic acid until moderate-to-severe ARDS at a stable Horowitz quotient (PaO 2 FiO 2-1 ) of 80 to 120 over a period of 30 min was obtained. Ventilation was then either performed with individualised FCV ( n  = 8) established by compliance-guided pressure titration or PCV ( n  = 8) with compliance-guided titration of the positive end-expiratory pressure and peak pressure set to achieve a tidal volume of 6 ml kg -1 over a period of 2 h.

MAIN OUTCOME MEASURES

Gas exchange parameters were assessed by the PaO 2 FiO 2-1 quotient and CO 2 removal by the PaCO 2 value in relation to required respiratory minute volume. Required catecholamine support for haemodynamic stabilisation was measured.

RESULTS

The FCV group showed significantly improved oxygenation [149.2 vs. 110.4, median difference (MD) 38.7 (8.0 to 69.5) PaO 2 FiO 2-1 ; P  = 0.027] and CO 2 removal [PaCO 2 7.25 vs. 9.05, MD -1.8 (-2.87 to -0.72) kPa; P  = 0.006] at a significantly lower respiratory minute volume [8.4 vs. 11.9, MD -3.6 (-5.6 to -1.5) l min -1 ; P  = 0.005] compared with PCV. In addition, in FCV-pigs, haemodynamic stabilisation occurred with a significant reduction of required catecholamine support [norepinephrine 0.26 vs. 0.86, MD -0.61 (-1.12 to -0.09) μg kg -1  min -1 ; P  = 0.037] during 2 ventilation hours.

CONCLUSION

In this oleic acid-induced porcine ARDS model, individualised FCV significantly improved gas exchange and haemodynamic stability compared with PCV.

TRIAL REGISTRATION

Protocol no.: BMBWF-66.011/0105-V/3b/2019).

Individualized flow-controlled versus conventional pressure-controlled ventilation in on-pump heart surgery (FLOWVENTIN HEARTSURG): study protocol for a randomized controlled trial

BACKGROUND

In on-pump cardiac surgery, lungs are at high risk of periprocedural organ impairment because of atelectasis formation, ventilator-induced lung injury, and hyperinflammation due to the cardiopulmonary bypass which results in postoperative pulmonary complications in half of this patient population. The new ventilation mode flow-controlled ventilation (FCV) uniquely allows full control of ins- and expiratory airway flows. This approach reduces the mechanical power of invasive ventilation as a possible cause of ventilator-induced lung injury. The scope of FLOWVENTIN HEARTSURG is to compare perioperative individualized FCV with best clinical practice pressure-controlled ventilation (PVC) modes in patients with elective on-pump cardiac surgery procedures. We hypothesize that the postoperative inflammatory response can be reduced by the perioperative application of FCV compared to PCV.

METHODS

FLOWVENTIN HEARTSURG is a single-center, randomized, parallel-group trial with two intervention arms: perioperative PCV modes (n = 70, PCV group) with an individualized positive end-expiratory pressure (PEEP) and a tidal volume of 6-8 ml/kg predicted bodyweight compared to perioperative FCV (n = 70, FCV group) with an individualized PEEP and driving pressure, resulting in a liberal tidal volume. As the primary study endpoint interleukin 8 plasma level is assessed 6 h after cardiopulmonary bypass as a surrogate biomarker of systemic and pulmonary inflammation. As secondary aims clinically relevant patient outcomes are analyzed, e.g., perioperative lung function regarding oxygenation indices, postoperative pulmonary and extra-pulmonary complications, SIRS-free days as well as ICU and total inpatient stays. As additional sub-studies with an exploratory approach perioperative right ventricular function parameters are assessed by echocardiography and perioperative lung aeration by electrical impedance tomography.

DISCUSSION

Current paradigms regarding protective low tidal volume ventilation are consciously left in the FCV intervention group in order to reduce mechanical power as a determinant of ventilator-induced lung injury in this high-risk patient population and procedures. This approach will be compared in a randomized controlled trial with current best clinical practice PCV in FLOWVENTIN HEARTSURG.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00018956 . Registered on 12 June 2020 (Version 1), last update on 22 August 2022 (Version 4).

Benefit of Flow-Controlled Over Pressure-Regulated Volume Control Mode During One-Lung Ventilation: A Randomized Experimental Crossover Study

BACKGROUND

Application of a ventilation modality that ensures adequate gas exchange during one-lung ventilation (OLV) without inducing lung injury is of paramount importance. Due to its beneficial effects on respiratory mechanics and gas exchange, flow-controlled ventilation (FCV) may be considered as a protective alternative mode of traditional pressure- or volume-controlled ventilation during OLV. We investigated whether this new modality provides benefits compared with conventional ventilation modality for OLV.

METHODS

Ten pigs were anaesthetized and randomly assigned in a crossover design to be ventilated with FCV or pressure-regulated volume control (PRVC) ventilation. Arterial partial pressure of oxygen (Pa o2 ), carbon dioxide (Pa co2 ), ventilation and hemodynamical parameters, and lung aeration measured by electrical impedance tomography were assessed at baseline and 1 hour after the application of each modality during OLV using an endobronchial blocker.

RESULTS

Compared to PRVC, FCV resulted in increased Pa o2 (153.7 ± 12.7 vs 169.9 ± 15.0 mm Hg; P = .002) and decreased Pa co2 (53.0 ± 11.0 vs 43.2 ± 6.0 mm Hg; P < .001) during OLV, with lower respiratory elastance (103.7 ± 9.5 vs 77.2 ± 10.5 cm H 2 O/L; P < .001) and peak inspiratory pressure values (27.4 ± 1.9 vs 22.0 ± 2.3 cm H 2 O; P < .001). No differences in lung aeration or hemodynamics could be detected between the 2 ventilation modalities.

CONCLUSIONS

The application of FCV in OLV led to improvement in gas exchange and respiratory elastance with lower ventilatory pressures. Our findings suggest that FCV may offer an optimal, protective ventilation modality for OLV.

Determining respiratory rate using measured expiratory time constant: A prospective observational study

PURPOSE

Potential negative implications associated with high respiratory rate (RR) are intrinsic positive end-expiratory pressure (PEEPi) generation, cardiovascular depression and possibly ventilator induced lung injury. Despite these negative consequences, optimal RR remains largely unknown. We hypothesized that without consideration of dynamics of lung emptying (i.e., the expiratory time constant [RC_EXP]) clinician settings of RR may exceed the frequency needed for optimal lung emptying.

MATERIALS AND METHODS

This prospective multicenter observational study measured RC_EXP in 56 intensive care patients receiving pressure-controlled ventilation. We compared set RR to the one predicted with RC_EXP (RR_P). Also, the subgroup of patients with prolonged RC_EXP was analyzed.

RESULTS

Overall, the absolute mean difference between the set RR and RR_P was 2.8 bpm (95% CI: 2.3-3.2). Twenty-nine (52%) patients had prolonged RC_EXP (>0.8 s), mean difference between set RR and RR_P of 3.1 bpm (95% CI: 2.3-3.8; p < 0.0001) and significantly higher PEEPi compared to those with RC_EXP ≤ 0.8 s: 4.4 (95% CI: 3.6-5.2) versus 1.5 (95% CI: 0.9-2.0) cmH₂O respectively, p < 0.0001.

CONCLUSIONS

Use of RR_P based on measured RC_EXP revealed that the clinician-set RR exceeded that predicted by RC_EXP in the majority of patients. Measuring RC_EXP appears to be a useful variable for adjusting the RR during mandatory mechanical ventilation.

Individualised flow-controlled ventilation versus pressure-controlled ventilation in a porcine model of thoracic surgery requiring one-lung ventilation: A laboratory study

BACKGROUND

Flow-controlled ventilation (FCV) enables precise determination of dynamic compliance due to a continuous flow coupled with direct tracheal pressure measurement. Thus, pressure settings can be adjusted accordingly in an individualised approach.

OBJECTIVE

The aim of this study was to compare gas exchange of individualised FCV to pressure-controlled ventilation (PCV) in a porcine model of simulated thoracic surgery requiring one-lung ventilation (OLV).

DESIGN

Controlled interventional trial conducted on 16 domestic pigs.

SETTING

Animal operating facility at the Medical University of Innsbruck.

INTERVENTIONS

Thoracic surgery was simulated with left-sided thoracotomy and subsequent collapse of the lung over a period of three hours. When using FCV, ventilation was performed with compliance-guided pressure settings. When using PCV, end-expiratory pressure was adapted to achieve best compliance with peak pressure adjusted to achieve a tidal volume of 6 ml kg -1 during OLV.

MAIN OUTCOME MEASURES

Gas exchange was assessed by the Horowitz index (= P aO 2 /FIO 2 ) and CO 2 removal by the P aCO 2 value in relation to required respiratory minute volume.

RESULTS

In the FCV group ( n  = 8) normocapnia could be maintained throughout the OLV trial despite a significantly lower respiratory minute volume compared to the PCV group ( n  = 8) (8.0 vs. 11.6, 95% confidence interval, CI -4.5 to -2.7 l min -1 ; P  < 0.001), whereas permissive hypercapnia had to be accepted in PCV ( P aCO 2 5.68 vs. 6.89, 95% CI -1.7 to -0.7 kPa; P  < 0.001). The Horowitz index was comparable in both groups but calculated mechanical power was significantly lower in FCV (7.5 vs. 22.0, 95% CI -17.2 to -11.8 J min -1 ; P  < 0.001).

CONCLUSIONS

In this porcine study FCV maintained normocapnia during OLV, whereas permissive hypercapnia had to be accepted in PCV despite a substantially higher minute volume. Reducing exposure of the lungs to mechanical power applied by the ventilator in FCV offers a possible advantage for this mode of ventilation in terms of lung protection.

A new perspective during laryngo-tracheal surgery: the use of an ultra-thin endotracheal tube (Tritube®) and flow-controlled ventilation—a retrospective case series and a review of the literature

Background

Upper airway surgery often poses a challenge to both anesthesiologists and surgeons, as airway access, mechanical ventilation, and surgical difficulties may occur in a tricky combination. To fulfill the need for a tubeless surgery, techniques such as apneic oxygenation or jet ventilation may be used, which carry the risk of several complications. The ultrathin cuffed endotracheal tube Tritube can be used with flow-controlled ventilation (FCV) to provide adequate surgical field and ventilation. To assess the feasibility, safety, and effectiveness of this technique, we describe a series of 21 patients, with various lung conditions, undergoing laryngo-tracheal surgery with FCV delivered via Tritube. Moreover, we perform a narrative systematic review to summarize clinical data on the use of Tritube during upper airway surgery.

Results

All patients were successfully intubated in one attempt with Tritube. The median (interquartile range [IQR]) tidal volume was 6.7 (6.2–7.1) mL/kg of ideal body weight, the median end-expiratory pressure was 5.3 (5.0–6.4) cmH2O, and the median peak tracheal pressure was 16 (15–18) cmH2O. The median minute volume was 5.3 (5.0–6.4) L/min. Median global alveolar driving pressure was 8 (7–9) cmH2O. The median maximum level of end-tidal CO2 was 39 (35–41) mmHg. During procedures involving laser, the maximum fraction of inspired oxygen was 0.3, with the median lowest peripheral oxygen saturation of 96% (94–96%). No complications associated with intubation or extubation occurred. In one patient, the ventilator needed to be rebooted for a software issue. In two (10%) patients, Tritube needed to be flushed with saline to remove secretions. In all patients, optimal visualization and accessibility of the surgical site were obtained, according to the surgeon in charge. Thirteen studies (seven case reports, two case series, three prospective observational studies, and one randomized controlled trial) were included in the narrative systematic review and described.

Conclusions

Tritube in combination with FCV provided adequate surgical exposure and ventilation in patients undergoing laryngo-tracheal surgery. While training and experience with this new method is needed, FCV delivered with Tritube may represent an ideal approach that benefits surgeons, anesthesiologists, and patients with difficult airways and compromised lung mechanics.

Flow-controlled ventilation maintains gas exchange and lung aeration in a pediatric model of healthy and injured lungs: A randomized cross-over experimental study

Flow-controlled ventilation (FCV) is characterized by a constant flow to generate active inspiration and expiration. While the benefit of FCV on gas exchange has been demonstrated in preclinical and clinical studies with adults, the value of this modality for a pediatric population remains unknown. Thus, we aimed at observing the effects of FCV as compared to pressure-regulated volume control (PRVC) ventilation on lung mechanics, gas exchange and lung aeration before and after surfactant depletion in a pediatric model. Ten anesthetized piglets (10.4 ± 0.2 kg) were randomly assigned to start 1-h ventilation with FCV or PRVC before switching the ventilation modes for another hour. This sequence was repeated after inducing lung injury by bronchoalveolar lavage and injurious ventilation. The primary outcome was respiratory tissue elastance. Secondary outcomes included oxygenation index (PaO₂/FiO₂), PaCO₂, intrapulmonary shunt (Qs/Qt), airway resistance, respiratory tissue damping, end-expiratory lung volume, lung clearance index and lung aeration by chest electrical impedance tomography. Measurements were performed at the end of each protocol stage. Ventilation modality had no effect on any respiratory mechanical parameter. Adequate gas exchange was provided by FCV, similar to PRVC, with sufficient CO₂ elimination both in healthy and surfactant-depleted lungs (39.46 ± 7.2 mmHg and 46.2 ± 11.4 mmHg for FCV; 36.0 ± 4.1 and 39.5 ± 4.9 mmHg, for PRVC, respectively). Somewhat lower PaO₂/FiO₂ and higher Qs/Qt were observed in healthy and surfactant depleted lungs during FCV compared to PRVC (p < 0.05, for all). Compared to PRVC, lung aeration was significantly elevated, particularly in the ventral dependent zones during FCV (p < 0.05), but this difference was not evidenced in injured lungs. Somewhat lower oxygenation and higher shunt ratio was observed during FCV, nevertheless lung aeration improved and adequate gas exchange was ensured. Therefore, in the absence of major differences in respiratory mechanics and lung volumes, FCV may be considered as an alternative in ventilation therapy of pediatric patients with healthy and injured lungs.

A case report of individualized ventilation in a COVID-19 patient - new possibilities and caveats to consider with flow-controlled ventilation

BACKGROUND

Flow-controlled ventilation (FCV) is a novel ventilation method increasingly being used clinically, particularly during the current COVID-19 pandemic. However, the continuous flow pattern in FCV during inspiration and expiration has a significant impact on respiratory parameters and ventilatory settings compared to conventional ventilation modes. In addition, the constant flow combined with direct intratracheal pressure measurement allows determination of dynamic compliance and ventilation settings can be adjusted accordingly, reflecting a personalized ventilation approach.

CASE PRESENTATION

A 50-year old women with confirmed SARS-CoV-2 infection suffering from acute respiratory distress syndrome (ARDS) was admitted to a tertiary medical center. Initial ventilation occurred with best standard of care pressure-controlled ventilation (PCV) and was then switched to FCV, by adopting PCV ventilator settings. This led to an increase in oxygenation by 30 %. Subsequently, to reduce invasiveness of mechanical ventilation, FCV was individualized by dynamic compliance guided adjustment of both, positive end-expiratory pressure and peak pressure; this intervention reduced driving pressure from 18 to 12 cm H2O. However, after several hours, compliance further deteriorated which resulted in a tidal volume of only 4.7 ml/kg.

CONCLUSIONS

An individualized FCV approach increased oxygenation parameters in a patient suffering from severe COVID-19 related ARDS. Direct intratracheal pressure measurements allow for determination of dynamic compliance and thus optimization of ventilator settings, thereby reducing applied and dissipated energy. However, although desirable, this personalized ventilation strategy may reach its limits when lung function is so severely impaired that patient's oxygenation has to be ensured at the expense of lung protective ventilation concepts.