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Peep titration based on the open lung approach during one lung ventilation in thoracic surgery: a physiological study.

ABSTRACT: BACKGROUND:During thoracic surgery in lateral decubitus, one lung ventilation (OLV) may impair respiratory mechanics and gas exchange. We tested a strategy based on an open lung approach (OLA) consisting in lung recruitment immediately followed by a decremental positive-end expiratory pressure (PEEP) titration to the best respiratory system compliance (CRS) and separately quantified the elastic properties of the lung and the chest wall. Our hypothesis was that this approach would improve gas exchange. Further, we were interested in documenting the impact of the OLA on partitioned respiratory system mechanics. METHODS:In thirteen patients undergoing upper left lobectomy we studied lung and chest wall mechanics, transpulmonary pressure (PL), respiratory system and transpulmonary driving pressure (?PRS and ?PL), gas exchange and hemodynamics at two time-points (a) during OLV at zero end-expiratory pressure (OLVpre-OLA) and (b) after the application of the open-lung strategy (OLVpost-OLA). RESULTS:The external PEEP selected through the OLA was 6?±?0.8 cmH2O. As compared to OLVpre-OLA, the PaO2/FiO2 ratio went from 205?±?73 to 313?±?86 (p?=?.05) and CL increased from 56?±?18 ml/cmH2O to 71?±?12 ml/cmH2O (p?=?.0013), without changes in CCW. Both ?PRS and ?PL decreased from 9.2?±?0.4 cmH2O to 6.8?±?0.6 cmH2O and from 8.1?±?0.5 cmH2O to 5.7?±?0.5 cmH2O, (p?=?.001 and p?=?.015 vs OLVpre-OLA), respectively. Hemodynamic parameters remained stable throughout the study period. CONCLUSIONS:In our patients, the OLA strategy performed during OLV improved oxygenation and increased CL and had no clinically significant hemodynamic effects. Although our study was not specifically designed to study ?PRS and ?PL, we observed a parallel reduction of both after the OLA. TRIAL REGISTRATION:TRN: ClinicalTrials.gov , NCT03435523 , retrospectively registered, Feb 14 2018.

SUBMITTER: Rauseo M

PROVIDER: S-EPMC6211445 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Peep titration based on the open lung approach during one lung ventilation in thoracic surgery: a physiological study.

Rauseo Michela M Mirabella Lucia L Grasso Salvatore S Cotoia Antonella A Spadaro Savino S D'Antini Davide D Valentino Franca F Tullo Livio L Loizzi Domenico D Sollitto Francesco F Cinnella Gilda G

BMC anesthesiology 20181031 1

<h4>Background</h4>During thoracic surgery in lateral decubitus, one lung ventilation (OLV) may impair respiratory mechanics and gas exchange. We tested a strategy based on an open lung approach (OLA) consisting in lung recruitment immediately followed by a decremental positive-end expiratory pressure (PEEP) titration to the best respiratory system compliance (C<sub>RS</sub>) and separately quantified the elastic properties of the lung and the chest wall. Our hypothesis was that this approach wo ...[more]

PMID: 30382819

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Project description:BackgroundIn the Protective Ventilation in Cardiac Surgery (PROVECS) randomized, controlled trial, an open-lung ventilation strategy did not improve postoperative respiratory outcomes after on-pump cardiac surgery. In this prespecified subanalysis, the authors aimed to assess the regional distribution of ventilation and plasma biomarkers of lung epithelial and endothelial injury produced by that strategy.MethodsPerioperative open-lung ventilation consisted of recruitment maneuvers, positive end-expiratory pressure (PEEP) = 8 cm H2O, and low-tidal volume ventilation including during cardiopulmonary bypass. Control ventilation strategy was a low-PEEP (2 cm H2O) low-tidal volume approach. Electrical impedance tomography was used serially throughout the perioperative period (n = 56) to compute the dorsal fraction of ventilation (defined as the ratio of dorsal tidal impedance variation to global tidal impedance variation). Lung injury was assessed serially using biomarkers of epithelial (soluble form of the receptor for advanced glycation end-products, sRAGE) and endothelial (angiopoietin-2) lung injury (n = 30).ResultsEighty-six patients (age = 64 ± 12 yr; EuroSCORE II = 1.65 ± 1.57%) undergoing elective on-pump cardiac surgery were studied. Induction of general anesthesia was associated with ventral redistribution of tidal volumes and higher dorsal fraction of ventilation in the open-lung than the control strategy (0.38 ± 0.07 vs. 0.30 ± 0.10; P = 0.004). No effect of the open-lung strategy on the dorsal fraction of ventilation was noted at the end of surgery after median sternotomy closure (open-lung = 0.37 ± 0.09 vs. control = 0.34 ± 0.11; P = 0.743) or in extubated patients at postoperative day 2 (open-lung = 0.63 ± 0.18 vs. control = 0.59 ± 0.11; P > 0.999). Open-lung ventilation was associated with increased intraoperative plasma sRAGE (7,677 ± 3,097 pg/ml vs. 6,125 ± 1,400 pg/ml; P = 0.037) and had no effect on angiopoietin-2 (P > 0.999).ConclusionsIn cardiac surgery patients, open-lung ventilation provided larger dorsal lung ventilation early during surgery without a maintained benefit as compared with controls at the end of surgery and postoperative day 2 and was associated with higher intraoperative plasma concentration of sRAGE suggesting lung overdistension.Editor’s perspective

Project description:STUDY OBJECTIVE:To evaluate the effects of dexmedetomidine on hypoxic pulmonary vasoconstriction (HPV) and oxygenation during one-lung ventilation (OLV) in adults undergoing thoracic surgery. DESIGN:Prospective, randomized, double-blinded trial. SETTING:Tertiary care, University-based hospital. PATIENTS:Nineteen adult patients undergoing thoracic surgery requiring OLV. INTERVENTIONS:During inhalational anesthesia with desflurane, patients were randomized to receive either dexmedetomidine (bolus dose of 0.3 ?g/kg followed by an infusion of 0.3 ?g/kg/hr) or saline placebo. MEASUREMENTS:Three arterial blood gas samples (ABG) were obtained to evaluate the effects of dexmedetomidine on oxygenation. Secondary outcomes included differences in hemodynamic parameters (heart rate and mean arterial pressure), end-tidal desflurane concentration required to maintain the bispectral index (BIS) at 40-60, supplemental fentanyl to maintain hemodynamic stability, and phenylephrine to keep the mean arterial pressure (MAP) within 10% of baseline values. MAIN RESULTS:Oxygenation during OLV did not change following the administration of dexmedetomidine (PaO2/FiO2 ratio of 188 ± 115 in dexmedetomidine patients versus 135 ± 70 mmHg in placebo patients). There were no differences in hemodynamic variables or depth of anaesthesia between the two groups. With the administration of dexmedetomidine, there was a decrease in the expired concentration of desflurane required to maintain the BIS at 40-60 when compared with the control group (4.5 ± 0.8% versus 5.1 ± 0.8%). In patients receiving dexmedetomidine, fentanyl requirements were decreased when compared to placebo (2.7 ?g/kg/patient versus 3.1 ?g/kg/patient). However, more patients receiving dexmedetomidine required phenylephrine to maintain hemodynamic stability (6 of 9 patients versus 3 of 10 patients) and the total dose of phenylephrine was greater in patients receiving dexmedetomidine when compared with placebo 10.3 ?g/kg/patient versus 1.1 ?g/kg/patient). CONCLUSION:Dexmedetomidine does not adversely affect oxygenation during OLV in adults undergoing thoracic surgical procedures. The improvement in oxygenation in the dexmedetomidine patients may be related to a decrease in the requirements for inhalational anaesthetic agents thereby limiting its effects on HPV.

Project description:BackgroundPositive end-expiratory pressure (PEEP) at minimum respiratory elastance during mechanical ventilation (MV) in patients with acute respiratory distress syndrome (ARDS) may improve patient care and outcome. The Clinical utilisation of respiratory elastance (CURE) trial is a two-arm, randomised controlled trial (RCT) investigating the performance of PEEP selected at an objective, model-based minimal respiratory system elastance in patients with ARDS.Methods and designThe CURE RCT compares two groups of patients requiring invasive MV with a partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio ≤ 200; one criterion of the Berlin consensus definition of moderate (≤ 200) or severe (≤ 100) ARDS. All patients are ventilated using pressure controlled (bi-level) ventilation with tidal volume = 6-8 ml/kg. Patients randomised to the control group will have PEEP selected per standard practice (SPV). Patients randomised to the intervention will have PEEP selected based on a minimal elastance using a model-based computerised method. The CURE RCT is a single-centre trial in the intensive care unit (ICU) of Christchurch hospital, New Zealand, with a target sample size of 320 patients over a maximum of 3 years. The primary outcome is the area under the curve (AUC) ratio of arterial blood oxygenation to the fraction of inspired oxygen over time. Secondary outcomes include length of time of MV, ventilator-free days (VFD) up to 28 days, ICU and hospital length of stay, AUC of oxygen saturation (SpO2)/FiO2 during MV, number of desaturation events (SpO2 < 88%), changes in respiratory mechanics and chest x-ray index scores, rescue therapies (prone positioning, nitric oxide use, extracorporeal membrane oxygenation) and hospital and 90-day mortality.DiscussionThe CURE RCT is the first trial comparing significant clinical outcomes in patients with ARDS in whom PEEP is selected at minimum elastance using an objective model-based method able to quantify and consider both inter-patient and intra-patient variability. CURE aims to demonstrate the hypothesized benefit of patient-specific PEEP and attest to the significance of real-time monitoring and decision-support for MV in the critical care environment.Trial registrationAustralian New Zealand Clinical Trial Registry, ACTRN12614001069640. Registered on 22 September 2014. (https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=366838&isReview=true) The CURE RCT clinical protocol and data usage has been granted by the New Zealand South Regional Ethics Committee (Reference number: 14/STH/132).

Project description:BackgroundPostoperative pulmonary complications (PPC) may result in longer duration of in-hospital stay and even mortality. Both thoracic surgery and intraoperative mechanical ventilation settings add considerably to the risk of PPC. It is unclear if one-lung ventilation (OLV) for thoracic surgery with a strategy of intraoperative high positive end-expiratory pressure (PEEP) and recruitment maneuvers (RM) reduces PPC, compared to low PEEP without RM.MethodsPROTHOR is an international, multicenter, randomized, controlled, assessor-blinded, two-arm trial initiated by investigators of the PROtective VEntilation NETwork. In total, 2378 patients will be randomly assigned to one of two different intraoperative mechanical ventilation strategies. Investigators screen patients aged 18 years or older, scheduled for open thoracic or video-assisted thoracoscopic surgery under general anesthesia requiring OLV, with a maximal body mass index of 35 kg/m2, and a planned duration of surgery of more than 60 min. Further, the expected duration of OLV shall be longer than two-lung ventilation, and lung separation is planned with a double lumen tube. Patients will be randomly assigned to PEEP of 10 cmH2O with lung RM, or PEEP of 5 cmH2O without RM. During two-lung ventilation tidal volume is set at 7 mL/kg predicted body weight and, during OLV, it will be decreased to 5 mL/kg. The occurrence of PPC will be recorded as a collapsed composite of single adverse pulmonary events and represents the primary endpoint.DiscussionPROTHOR is the first randomized controlled trial in patients undergoing thoracic surgery with OLV that is adequately powered to compare the effects of intraoperative high PEEP with RM versus low PEEP without RM on PPC. The results of the PROTHOR trial will support anesthesiologists in their decision to set intraoperative PEEP during protective ventilation for OLV in thoracic surgery.Trial registrationThe trial was registered in clinicaltrials.gov ( NCT02963025 ) on 15 November 2016.

Project description:We evaluated the effectiveness of pressure-controlled ventilation-volume guaranteed (PCV-VG) mode combined with open-lung approach (OLA) in patients during one-lung ventilation (OLV). First, 176 patients undergoing thoracoscopic surgery were allocated randomly to four groups: PCV+OLA (45 cases, PCV-VG mode plus OLA involving application of individualized positive end-expiratory pressure (PEEP) after a recruitment maneuver), PCV (44 cases, PCV-VG mode plus standard lung-protective ventilation with fixed PEEP of 5?cmH2O), VCV+OLA (45 cases, volume-controlled ventilation (VCV) plus OLA), and VCV (42 cases, VCV plus standard lung-protective ventilation). Mean airway pressure (P mean), dynamic compliance (Cdyn), PaO2/FiO2 ratio, intrapulmonary shunt ratio (Qs/Qt), dead space fraction (V D/V T), and plasma concentration of neutrophil elastase were obtained to assess the effects of four lung-protective ventilation strategies. At 45?min after OLV, the median (interquartile range (IQR)) P mean was higher in the PCV+OLA group (13.00 (12.00, 13.00) cmH2O) and the VCV+OLA group (12.00 (12.00, 14.00) cmH2O) than in the PCV group (11.00 (10.00, 12.00) cmH2O) and the VCV group (11.00 (10.00, 12.00) cmH2O) (P < 0.05); the median (IQR) Cdyn was higher in the PCV+OLA group (27.00 (24.00, 32.00) mL/cmH2O) and the VCV+OLA group (27.00 (22.00, 30.00) mL/cmH2O) than in the PCV group (23.00 (21.00, 25.00) mL/cmH2O) and the VCV group (20.00 (18.75, 21.00) mL/cmH2O) (P < 0.05); the median (IQR) Qs/Qt in the PCV+OLA group (0.17 (0.16, 0.19)) was significantly lower than that in the PCV group (0.19 (0.18, 0.20)) and the VCV group (0.19 (0.17, 0.20)) (P < 0.05); V D/V T was lower in the PCV+OLA group (0.18 ± 0.05) and the VCV+OLA group (0.19 ± 0.07) than in the PCV group (0.21 ± 0.07) and the VCV group (0.22 ± 0.06) (P < 0.05). The concentration of neutrophil elastase was lower in the PCV+OLA group than in the PCV, VCV+OLA, and VCV groups at total-lung ventilation 10?min after OLV (162.47 ± 25.71, 198.58 ± 41.99, 200.84 ± 22.17, and 286.95 ± 21.10?ng/mL, resp.) (P < 0.05). In conclusion, PCV-VG mode combined with an OLA strategy leads to favorable effects upon lung mechanics, oxygenation parameters, and the inflammatory response during OLV.

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Peep titration based on the open lung approach during one lung ventilation in thoracic surgery: a physiological study.

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Peep titration based on the open lung approach during one lung ventilation in thoracic surgery: a physiological study.

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