Volume-controlled Ventilation Mode Research Articles

Evaluation of Volume Controlled Ventilation Mode and Volume Guaranteed Pressure Controlled Ventilation Modes in Lateral Decubitus Position; Randomized Controlled Study

Evaluation of Volume Controlled Ventilation Mode and Volume Guaranteed Pressure Controlled Ventilation Modes in Lateral Decubitus Position; Randomized Controlled Study

The Ventilatory Changes of Pediatric Peroral Endoscopic Myotomy Patients.

Peroral endoscopic myotomy (POEM) has proven to be a successful treatment method for achalasia in both adult and pediatric patients. Yet, there is a lack of evidence for anaesthetic management of pediatric patients who underwent POEM procedure. In this study, we aim to present perioperative and postoperative management strategies for pediatric patients with achalasia from in anaesthesia aspect. Medical records were reviewed for 16 pediatric patients at a single center who underwent POEM procedure for achalasia between 2017 and 2020. Patients' data regarding demographics, preoperative diet, body mass index, perioperative monitoring and vitals, airway management, anaesthesia maintenance, mechanical ventilation settings duration of recovery, length of stay, pain management and adverse events were evaluated. The study cohort included 7 female and 9 male patients with a mean age of 5.5 years. Anaesthesia maintenance was provided with 0.8-1.2 minimum alveolar concentration sevoflurane in a 40-60% O2-air mixture, Remifentanil infusion and bolus doses of Rocuronium. The median age was 3 years for patients ventilated in pressure controlled ventilation mode and 10 years in volume controlled ventilation mode. Respiration rate and minute ventilation were adjusted to maintain end tidal carbon dioxide (ETCO2) below 45 mmHg. Needle decompression was applied for 14 patients (87.5%) for treatment of capnoperitoneum. The mean procedure duration and recovery room duration were 66 (±22.9) minutes and 62 (±21) minutes, respectively. Postoperative pain management is provided with paracetamol and tramadol in total 8 patients (50%). There was no adverse event during postoperative period and all patients discharged in a mean time of 3 days. POEM has demonstrated encouraging outcomes in terms of safety and effectiveness in pediatric patients. Due to challenging nature of the pediatric patients, it is important to acknowledge that the procedure requires specialized anaesthesia management. Management of perioperative complications of increased ETCO2 requires understanding the physiologic results of pneumo-mediastinum and pneumo-peritoneum. Beside the known anaesthetic management strategies, a tailored approach should be adopted for each patient. Further investigations should be conducted to develop standardized management.

Comparison of Volume-Controlled Ventilation (VCV) Mode and Pressure-Controlled Ventilation (PCV) Mode in Patients Undergoing Lumbar Spine Surgery in the Prone Position

Abstract Background The prone position is commonly required to enable surgical access during lumbar spine surgery. When a patient moves into the prone position, inferior vena cava obstruction causes reduced venous return and increase thoracic pressure results in reduced left ventricular compliance, leading to a decreased cardiac index (CI). Aim of the Work The aim of this study, we will compare the effects of the VCV and PCV on peak airway pressure (P peak), ETCO2 as a primary outcome ABG, SPO2, and hemodynamics as MAP, HR and as a secondary outcome in the prone position. Patients and Methods This prospective, single blinded study included 60 patients who assigned randomly into two equal groups: group A: patients on volume-controlled ventilation mode VCV and group B: patients on pressure-controlled ventilation mode PCV. Results Baseline characteristics (age, sex, BMI, ASA physical status, duration of anesthesia and surgery) were insignificantly different between both groups. Heart rate and MAP at supine and prone positions at all time measurements were insignificantly different between both groups. P peak and SpO2 at supine and prone positions at all time measurements were insignificantly different between both groups. Respiratory rate and ETCO2 at supine and prone positions at all time measurements were insignificantly different between both groups. Conclusion No significant difference between two modes of ventilation VCV and PCV in patients undergoing lumbar spine surgery in the prone position as regard P peak, ETCO2, SPO2, and hemodynamics.

Pressure-controlled versus Volumecontrolled Ventilation during One Lung Ventilation for Empyema Thoracis: A Randomised Control Trial

Pressure-controlled versus Volumecontrolled Ventilation during One Lung Ventilation for Empyema Thoracis: A Randomised Control Trial

Comparison of the effect of pressure control and volume control ventilation on endotracheal tube cuff pressure in patients undergoing general anesthesia and mechanical ventilation: a parallel randomized clinical trial

BackgroundEndotracheal intubation and mechanical ventilation are prevalent interventions in the operating room and intensive care unit. Recently, the complications of endotracheal tube cuff pressure have been a topic of interest. Therefore, this study compared the effect of pressure control and volume control ventilation modes on the endotracheal cuff pressure rate in patients undergoing general anesthesia and mechanical ventilation.MethodsIn this triple-blinded randomized clinical trial, 50 patients undergoing open limb surgery and inguinal hernia were allocated to two groups of 25 based on inclusion criteria. After intubation, one group underwent ventilation on the pressure control ventilation mode, and the other underwent ventilation on the volume control ventilation mode. In both groups, using a manometer, the cuff’s pressure was first adjusted in the range of 25–30 cm of water. Then, the cuff pressure was measured at 10, 20, and 30 min intervals. The data were statistically analyzed using independent t-test, and two-way repeated measures ANOVA.ResultsThe present study’s findings showed that cuff pressure has significantly decreased over time in both study groups (F = 117.7, P < 0.001). However, a repeated measures ANOVA with a Greenhouse-Geisser correction showed no interaction between time and groups (F = 0.019, P = 0.98). The two groups had no significant difference in cuff pressure (F = 0.56, P = 0.458).ConclusionSince the cuff pressure has been significantly reduced in both groups over time, continuous monitoring of endotracheal tube cuff pressure in patients undergoing mechanical ventilation is essential. Therefore, it is suggested to keep the cuff pressure within the recommended range to prevent complications resulting from cuff pressure reduction, such as aspiration and ventilation decrease.Trial registrationThe study was registered in the Iranian Registry of Clinical Trial on 23/02/2019 (trial registration number: IRCT20181018041376N1).

Features of Mechanical Lung Ventilation During Robot-Assisted Radical Prostatectomy in Patients with Different Body Mass Index

The aim of the study. To evaluate effects of carboxyperitoneum and steep Trendenburg position on respiratory biomechanics and gas exchange indicators in patients with different body mass index (BMI) during robotic-assisted radical prostatectomy (RRP). To develop an algorithm for choosing the optimal mechanical lung ventilation (MLV) regimen. Materials and methods. The study included 141 patients with verified prostate cancer who were candidates for RPR. Participants were divided into 2 groups based on BMI: group I included 88 patients with BMI30 kg/m2, group II — 53 patients with BMI30 kg/m2. Indicators of respiratory biomechanics and gas exchange during ventilation in various modes (Volume Controlled Ventilation (VCV), Pressure Controlled Ventilation (PCV), Pressure Controlled– Inverse Ratio Ventilation (PC-IRV) were analyzed in each group at 5 consecutive stages of the procedure.Results. The key parameters evidencing the effectiveness and safety of MLV during RRP procedure did not vary significantly under various ventilation regimens in the group of patients with a BMI30 kg/m2. Whilst in obese patients the use of VCV mode resulted in a significant increase of airway peak pressure (Ppeak) already at the stage of placing them into a steep Trendelenburg position (35°), thus endangering with the development of ventilator-induced lung injury. Increased Ppeak was also accompanied by the drop in oxygen saturation and significantly lower SpO₂ values, starting from the stage of applying carboxyperitoneum and until the end of surgical intervention.Conclusion. In non-obese patients, there’s no particular ventilator regimen that is crucial for achieving the safety and effectiveness of RRP anesthesia management, all regimens can be used. In patients with BMI30 kg/m2 PCV regimen and PC-IRV with inhalation/exhalation ratio of 1.5:1 can be considered as the optimal strategy for MLV during anesthesia for RRP surgery.

Capnometry after an inspiratory breath hold, PLAT CO2 , as a surrogate for in mild to moderate pediatric acute respiratory distress syndrome: A feasibility study.

Accurate and reliable noninvasive methods to estimate gas exchange are necessary to guide clinical decisions to avoid frequent blood samples in children with pediatric acute respiratory distress syndrome (PARDS). We aimed to investigate the correlation and agreement between end-tidal measured immediately after a 3-s inspiratory-hold (PLAT CO2 ) by capnometry and measured by arterial blood gases (ABG) in PARDS. Prospective cohort study. Seven-bed Pediatric Intensive Care Unit, Hospital El Carmen de Maipú, Chile. Thirteen mechanically ventilated patients aged ≤15 years old undergoing neuromuscular blockade as part of management for PARDS. None. All patients were in volume-controlled ventilation mode. The regular end-tidal (without the inspiratory hold) was registered immediately after the ABG sample. An inspiratory-hold of 3 s was performed for lung mechanics measurements, recording in the breath following the inspiratory-hold. (PLAT CO2 ). End-tidal alveolar dead space fraction (AVDSf) was calculated as and its surrogate (S)AVDSf as . Measurements of were considered the gold standard. We performed concordance correlation coefficient (ρc), Spearman's correlation (rho), and Bland-Altmann's analysis (mean difference ± SD [limits of agreement, LoA]). Eleven patients were included, with a median (interquartile range) age of 5 (2-11) months. Tidal volume was 5.8 (5.7-6.3) mL/kg, PEEP 8 (6-8), driving pressure 10 (8-11), and plateau pressure 17 (17-19) cm H2 O. Forty-one paired measurements were analyzed. was higher than (52 mmHg [48-54] vs. 42 mmHg [38-45], p < 0.01), and there were no significant differences with PLAT CO2 (50 mmHg [46-55], p > 0.99). The concordance correlation coefficient and Spearman's correlation between and PLAT CO2 were robust (ρc = 0.80 [95% confidence interval [CI]: 0.67-0.90]; and rho = 0.80, p < 0.001.), and for were weak and strong (ρc = 0.27 [95% CI: 0.15-0.38]; and rho = 0.63, p < 0.01). The bias between PLAT CO2 and was -0.4 ± 3.5 mmHg (LoA -7.2 to 6.4), and between and was -8.5 ± 4.1 mmHg (LoA -16.6 to -0.5). The correlation between AVDSf and (S)AVDSf was moderate (rho = 0.55, p < 0.01), and the mean difference was -0.5 ± 5.6% (LoA -11.5 to 10.5). This pilot study showed the feasibility of measuring end-tidal CO2 after a 3-s end-inspiratory breath hole in pediatric patients undergoing controlled ventilation for ARDS. Encouraging preliminary results warrant further study of this technique.

Plateau Pressure and Driving Pressure in Volume- and Pressure-Controlled Ventilation: Comparison of Frictional and Viscoelastic Resistive Components in Pediatric Acute Respiratory Distress Syndrome.

To examine frictional, viscoelastic, and elastic resistive components, as well threshold pressures, during volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) in pediatric patients with acute respiratory distress syndrome (ARDS). Prospective cohort study. Seven-bed PICU, Hospital El Carmen de Maipú, Chile. Eighteen mechanically ventilated patients less than or equal to 15 years old undergoing neuromuscular blockade as part of management for ARDS. None. All patients were in VCV mode during measurement of pulmonary mechanics, including: the first pressure drop (P1) upon reaching zero flow during the inspiratory hold, peak inspiratory pressure (PIP), plateau pressure (P PLAT ), and total positive end-expiratory pressure (tPEEP). We calculated the components of the working pressure, as defined by the following: frictional resistive = PIP-P1; viscoelastic resistive = P1-P PLAT ; purely elastic = driving pressure (ΔP) = P PLAT -tPEEP; and threshold = intrinsic PEEP. The procedures and calculations were repeated on PCV, keeping the same tidal volume and inspiratory time. Measurements in VCV were considered the gold standard. We performed Spearman correlation and Bland-Altman analysis. The median (interquartile range [IQR]) for patient age was 5 months (2-17 mo). Tidal volume was 5.7 mL/kg (5.3-6.1 mL/kg), PIP cm H 2 O 26 (23-27 cm H 2 O), P1 23 cm H 2 O (21-26 cm H 2 O), P PLAT 19 cm H 2 O (17-22 cm H 2 O), tPEEP 9 cm H 2 O (8-9 cm H 2 O), and ΔP 11 cm H 2 O (9-13 cm H 2 O) in VCV mode at baseline. There was a robust correlation (rho > 0.8) and agreement between frictional resistive, elastic, and threshold components of working pressure in both modes but not for the viscoelastic resistive component. The purely frictional resistive component was negligible. Median peak inspiratory flow with decelerating-flow was 21 (IQR, 15-26) and squared-shaped flow was 7 L/min (IQR, 6-10 L/min) ( p < 0.001). P PLAT , ΔP, and tPEEP can guide clinical decisions independent of the ventilatory mode. The modest purely frictional resistive component emphasizes the relevance of maintaining the same safety limits, regardless of the selected ventilatory mode. Therefore, peak inspiratory flow should be studied as a mechanism of ventilator-induced lung injury in pediatric ARDS.

Surgical bleeding in patients undergoing posterior lumbar inter-body fusion surgery: a randomized clinical trial evaluating the effect of two mechanical ventilation mode types

BackgroundThe purpose of the study was to compare the effect of using volume-controlled ventilation (VCV) versus pressure-controlled ventilation (PCV) on blood loss in patients undergoing posterior lumbar inter-body fusion (PLIF) surgery.MethodsIn a randomized, single-blinded, parallel design, 78 patients, candidates for PLIF surgery, were randomly allocated into two groups of 39 to be mechanically ventilated using VCV or PCV mode. All the patients were operated in prone position by one surgeon. Amount of intraoperative surgical bleeding, transfusion requirement, surgeon satisfaction, hemodynamic parameters, heart rate, and blood pressure were measured as outcomes.ResultsPCV group showed slightly better outcomes than VCV group in terms of mean blood loss (431 cc vs. 465 cc), transfusion requirement (0.40 vs. 0.43 unit), and surgeon satisfaction (82.1% vs. 74.4%); however, the differences were not statistically significant. Diastolic blood pressure 90 and 105 min after induction were significantly lower in PCV group (P = 0.043–0.019, respectively); however, blood pressure at other times, hemoglobin levels, and mean heart rate were similar in two groups.ConclusionsIn patients undergoing posterior lumbar inter-body fusion surgery, mode of ventilation cannot make significant difference in terms of blood loss; however, some minor benefits in outcomes may lead to the selection of PCV rather than VCV. More studies with larger sample size, and investigating more factors may be needed.

Mechanical power in AVM-2 versus conventional ventilation modes in various ARDS lung models. Bench study

Introduction Mechanical power has been linked to ventilator induced lung injury and mortality in acute respiratory distress syndrome (ARDS). Adaptive Ventilator Mode-2 is a closed-loop pressure-controlled mode with an optimal targeting scheme based on the inspiratory power equation that adjusts the respiratory rate and tidal volume to achieve a target minute ventilation. Conceptually, this mode should reduce the mechanical power delivered to the patients and thus reduce the incidence of ventilator induced lung injury. Methods A bench study using a lung simulator was conducted. We constructed three passive single compartment ARDS models (Mild, Moderate, Severe) with compliance of 40, 30, 20 ml/cmH2O respectively, and resistance of 10 cmH2O/L/s, with IBW 70 kg. We compared three different ventilator modes: AVM-2, Pressure Regulated Volume Control (PRVC), and Volume Controlled Ventilation (VCV) in six different scenarios: 3 levels of minute ventilation 7, 10.5, and 14 Lit/min (Experiment 1, 2, and 3 respectively), each with 3 different PEEP levels 10, 15, and 20 cmH2O (Experiment A, B, and C respectively) termed 1A, 1B, 1C, 2A, 2B, 2C, 3A, 3B, 3C respectively for a total of 81 experiments. The AVM-2 mode automatically selects the optimal tidal volume and respiratory rate per the dialed percent minute ventilation with an I:E ratio of 1:1. In the PRVC and VCV (constant flow) we selected target tidal volume 6ml/kg/IBW (420 ml) and respiratory rate adjusted to match the minute ventilation for the AVM-2 mode. I:E ratio was kept 1:2. The mechanical power delivered by the ventilator for each mode was computed and compared between the three modes in each experiment. Statistical analysis was done using Kruskal-Wallis test to analyze the difference between the three modes, post HOC Tukey test was used to analyze the difference between each mode where P &lt; 0.05 was considered statistically significant. The Power Compliance Index was calculated and compared in each experiment. Multiple regression analysis was performed in each mode to test the correlation of the variables of mechanical power to the total calculated power. Results There were statistically significant differences (P &lt; 0.001) between all the three modes regarding the ventilator delivered mechanical power. AVM-2 mode delivered significantly less mechanical power than VCV which in turn was less than PRVC. The Power Compliance index was also significantly lower (P &lt; 0.01) in the AVM-2 mode compared to the other conventional modes. Multiple regression analysis indicated that in AVM-2 mode, the driving pressure (P = 0.004), tidal volume (P &lt; 0.001), respiratory rate (P = 0.011) and PEEP (P &lt; 0.001) were significant predictors in the model. In the VCV mode, the respiratory rate (P 0&lt; 0.001) and PEEP (P &lt; 0.001) were significant predictors, but the driving pressure was a non-significant predictor (P = 0.08). In PRVC mode, the respiratory rate (P &lt; 0.001), PEEP (P &lt; 0.001) and driving pressure (P &lt; 0.001) were significant predictors. Conclusion AVM2 mode delivered less mechanical power compared to two conventional modes using low tidal volume in an ARDS lung model with different severities. This might translate to the reduction of the incidence of ventilator induced lung injury. Results need to be validated in clinical studies.

Mechanical Power Differs Between Pressure-Controlled Ventilation and Different Volume-Controlled Ventilation Modes

OBJECTIVES:Mechanical power (MP) is a way of estimating the energy delivered by the ventilator to the patient. For both volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) methods have been described to calculate the MP. The pressure-volume (PV) loop, from which the MP is calculated, is different for VCV compared with PCV. We aimed to compare the MP of VCV with zero pause time (VCV-0), VCV with 10% pause time (VCV-10), and PCV within patients in different patient categories based on severity of lung injury.DESIGN:In a proof-of-concept study, we enrolled 46 mechanically ventilated patients without spontaneous breathing efforts. Baseline measurements were done in pressure-controlled mode. Subsequently, measurements were done in VCV-0 and VCV-10. Tidal volume and all other settings were kept the same.SETTING:ICU, single university medical center.PATIENTS:Fifty-eight cases in 46 patients on controlled ventilation modes.INTERVENTIONS:Comparison between the MP of PCV, VCV-0, and VCV-10.MEASUREMENT AND MAIN RESULTS:The mean MP of VCV-0, VCV-10, and PCV was 19.30, 21.80, and 20.87 J/min, respectively (p < 0.05 for all comparisons). The transpulmonary MP of VCV-0, VCV-10, and PCV was 6.75, 8.60, and 7.99 J/min, respectively (p < 0.05 for all comparisons).CONCLUSIONS:In patients ventilated in a controlled mode, VCV without pause time had the lowest MP followed by PCV. VCV with 10% pause time had the highest MP.

Application of Different Ventilation Modes Combined with AutoFlow Technology in Thoracic Surgery.

To investigate the effect of AutoFlow on airway pressure and hemodynamics in mechanical ventilation constant volume-control ventilation mode, 100 patients receiving mechanical ventilation were randomly divided into observation group (SIMV-PSV-PEEP + AutoFlow) and control group (SIMV-PSV-PEEP). The results showed that the peak airway pressure and average airway pressure decreased with different flow rate settings and automatic flow conversion (P < 0.05). The peak airway pressure and mean airway pressure decreased with different resistance settings (P < 0.05). With different compliance settings, the peak airway pressure and average airway pressure decreased after being assisted with an automatic converter (P < 0.05). Adding AutoFlow on the basis of SIMV-PSV mode can significantly reduce peak inspiratory pressure (PIP), mean airway pressure (Pmean), and airway resistance (R). There was no significant difference in hemodynamic monitoring results between the observation group and the control group. It is proved that the SIMV constant volume-controlled ventilation mode combined with AutoFlow can not only ensure tidal volume but also avoid excessive airway pressure, which has little effect on hemodynamics.

Intraoperative Protective Mechanical Ventilation in Dogs: A Randomized Clinical Trial.

ObjectiveTo evaluate gas exchange, respiratory mechanics, and hemodynamic impact of mechanical ventilation with low tidal volume (VT) in dogs with the use of positive end-expiratory pressure (PEEP) or preceded by alveolar recruitment maneuver (ARM).Study DesignProspective randomized clinical trial.AnimalsTwenty-one healthy client-owned mesocephalic healthy dogs, 1–7 years old, weighing 10–20 kg, and body condition scores 4–6/9 admitted for periodontal treatment.MethodsIsoflurane-anesthetized dogs in dorsal recumbency were ventilated until 1 h with a volume-controlled ventilation mode using 8 mL kg−1 of VT. The dogs were distributed in 2 groups: in the ARM group, PEEP starts in 0 cmH2O, increasing gradually 5 cmH2O every 3 min, until reach 15 cmH2O and decreasing in the same steps until 5 cmH2O, maintaining this value until the end; and PEEP group, in which the pressure 5 cmH2O was instituted from the beginning of anesthesia and maintained the same level up to the end of the anesthesia. Cardiopulmonary, metabolic, oxygenation parameters, and respiratory mechanics were recorded after the anesthesia induction (baseline—BL), 15, 45, and 75 min after BL and during the recovery.ResultsThe ARM increased the static compliance (Cst) (15 min after baseline) when compared with baseline moment (24.9 ± 5.8 mL cmH20−1 vs. 20.7 ± 5.4 mL cmH20−1–p = 0.0364), oxygenation index (PaO2/FIO2) (505.6 ± 59.2 mmHg vs. 461.2 ± 41.0 mmHg—p = 0.0453) and reduced the shunt fraction (3.4 ± 2.4% vs. 5.5 ± 1.6%—p = 0.062). In the PEEP group, no statistical differences were observed concerning the variables evaluated. At the beginning of the evaluation, the driving pressure (DP) before ARM was significantly greater than all other evaluation time points (6.9 ± 1.8 cmH20).Conclusions and Clinical RelevanceThe use of 8 mL kg−1 of VT and 5 cmH20 PEEP without ARM maintain adequate oxygenation and mechanical ventilation in dental surgeries for up to 1 h. The use of ARM slightly improved compliance and oxygenation during the maneuver.

Abstract No.: ABS3339: Effects of volume controlled and pressure controlled volume guaranteed modes of ventilation on respiratory dynamics during laparoscopic surgery in children: A prospective observational study

Background & Aims:The aim of the study was to compare the effects of Volume controlled ventilation (VCV) and Pressure controlled volume guaranteed ventilation (PCV-VG), which delivers the target tidal volume at the lowest possible pressure, on respiratory dynamics during paediatric laparoscopic surgery.Methods:In this prospective observational study, 52 patients of 0-15 years were included; (n= 26) each for VCV and PCV-VG.fraction of inspired oxygen(FiO2)50%, tidal volume 6-10 ml/kg, age appropriate respiratory rate (RR) to maintain end-tidal carbon dioxide (EtCO2) between 35-40 mm Hg, PEEP 4 cm and P-limit 10 cm above the initial peak pressure were set. Peak inspiratory pressure (PIP), Plateau pressure (PlatP), expiredtidal volume (VTe)/kg, compliance (Compl), airway resistance (R), ETCO2 and saturation of O2 (SaO2)were noted after intubation, creation of pneumoperitoneum, changing position, desufflation and change of position to supine.Results:Demographic criteria, haemodynamic parameters, set and measured respiratory parameters at all time points were similar inboth groups. Trendelenburg position was required in 11 children in VCV and 13 in PCV-VG group. Following this, there was similar increase in PIP, PlatP, R and decrease in CompL in both groups. However, significant increase in RR was required inVCV group (percentage change in RR- —VCV: 3.5±5.01, PCV-VG : 0±00, p=0.039) to maintain normal ETCO2.Conclusion:Either VCV or PCV-VG mode of ventilation, can be used during paediatric laparoscopic surgery in supine position.However, with Trendelenburg position, PCV-VG provides a marginal advantage over VCV mode of ventilation.

Comparison of the effects of volume-controlled ventilation and pressure-controlled ventilation modes on hemodynamics, respiratory mechanics and blood gas parameters in patients undergoing laparoscopic cholecystectomy

Background: This study aimed to compare the changes induced by VCV and PCV modes in hemodynamics, respiration (airway pressures, gas exchange parameters) and metabolism (acid-base balance) in patients undergoing laparoscopic cholecystectomy.Methods: Patients were divided into two randomised groups as volume-controlled ventilation (VCV) group (VC) and pressure-controlled ventilation (PCV) group (PC). The following parameters were recorded at 3 different time points: T1: in supine position 10 minutes after induction of anaesthesia, T2: 15 minutes after CO2 insufflation in inverted Trendelenburg position (head 30 degrees up), T3: 10 minutes after CO2 desufflation. HR, SpO2, SAP (systolic arterial pressure), DAP (diastolic arterial pressure), MAP (mean arterial pressure), PetCO2 (end-tidal carbon dioxide pressure), Ppeak, Pplateau, Pmean, Vt (tidal volume) and compliance with the available data, the cases in both groups Vd, Vd/Vt ratios and P(A-a)O2 were calculated. Arterial blood gas parameters (pH, PaO2, PaCO2, SaO2, P(a-et)CO2) values were recorded.Results: It was found that Ppeak and Pplateau values were significantly higher in the VC group (p&lt;0.05). It was found that compliance was significantly higher in the PC group (p&lt;0.05) (p&lt;0.01). In the postoperative period, it was found that PaO2 values were significantly higher in the PC group compared to the VC group (p&lt;0.05). It was found that the P(A-a)O2 values of the PC group were significantly higher than those of the VC group during the desufflation phase (p&lt;0.05).Conclusions: We think that PCV mode can be a good alternative for the prevention and correction of physiopathological changes due to laparoscopic surgery.

Assessment of respiratory system compliance under pressure control ventilation without an inspiratory pause maneuver

Objective. The measurement of the static compliance of the respiratory system (C stat) during mechanical ventilation requires zero end-inspiratory flow. An inspiratory pause maneuver is needed if the zero end-inspiratory flow condition cannot be satisfied under normal ventilation. Approach. We propose a method to measure the quasi-static respiratory compliance (C qstat) under pressure control ventilation mode without the inspiratory pause maneuver. First, a screening strategy was applied to filter out breaths affected strongly by spontaneous breathing efforts or artifacts. Then, we performed a virtual extrapolation of the flow-time waveform when the end-inspiratory flow was not zero, to allow for the calculation of C qstat for each kept cycle. Finally, the output C qstat was obtained as the average of the smallest 40 C qstat measurements. The proposed method was validated against the gold standard C stat measured from real clinical settings and compared with two reported algorithms. The gold standard C stat was obtained by applying an end-inspiratory pause maneuver in the volume-control ventilation mode. Main results. Sixty-nine measurements from 36 patients were analyzed. The Bland–Altman analysis showed that the bias of agreement for C qstat versus the gold standard measurement was –0.267 ml/cmH2O (95% limits of agreement was –4.279 to 4.844 ml/cmH2O). The linear regression analysis indicated a strong correlation (R 2 = 0.90) between the C qstat and gold standard. Significance. The results showed that the C qstat can be accurately estimated from continuous ventilator waveforms, including spontaneous breathing without an inspiratory pause maneuver. This method promises to provide continuous measurements compliant with mechanical ventilation.

Flow-controlled expiration (FLEX) homogenizes pressure distribution in a four compartment physical model of the respiratory system with chest wall compliance

Objective. Flow-controlled expiration (FLEX) has been shown to attenuate ventilator-induced lung injury in animal models. It has also shown to homogenize compartmental pressure distribution in a physical model of the inhomogeneous respiratory system having independent compartments. We hypothesized that the homogenizing effects of FLEX are also effective in this regard when the independence of compartments is suspended by simulated chest wall compliance. Approach. A four compartment physical model of the respiratory system having chest wall compliance (137 ml/cmH2O) was developed. Two of the four compartments had high compliance (18 ml/cmH2O) and two had low compliance (10 ml/cmH2O). These compartments were each combined with either high (6.8 cmH2O·s/l) or low resistance (3.5 cmH2O·s/l). The model was ventilated in the volume-controlled ventilation mode with either passive expiration or with FLEX. The maximal pressure differences (ΔP max) and the maximal differences of mean pressure (ΔP mean) between the compartments during expiration were determined. Main results. With passive expiration ΔP max reached up to 3.4 ± 0.03 cmH2O but only 0.9 ± 0.01 cmH2O with FLEX (p < 0.001). Maximal differences of ΔP mean were significantly lower with FLEX as compared to passive expiration (extending up to 0.4 ± 0.04 cmH2O versus 2.0 ± 0.15 cmH2O, p < 0.001). Significance. The homogenizing effects of FLEX on compartmental pressure distribution could be reproduced in a more complex physical model of the inhomogeneous respiratory system having chest wall compliance and might be a mechanism underlying the lung protective effects of ventilation with FLEX.

Spontaneous breathing for managing analgesia during balanced anesthesia with remifentanil and desflurane: a prospective, single center randomized controlled trial.

The main goal of anesthesiology is to achieve the best level of analgesia and a fast recovery of consciousness following anesthesia. The preservation of spontaneous breathing during general anesthesia with anesthetic gases is practiced by many anesthetists. However, very few studies have dealt with these positive properties of volatile anesthetics such as sevoflurane or desflurane. Remifentanil is a very short half-life opiate that combines sufficient intra-operative analgesia with a fast post-operative recovery time. We tested the hypothesis that spontaneous breathing can reduce overdosing with remifentanil during desflurane anesthesia. In this prospective, single center, multiple anesthetist study, 30 patients were randomized into two groups (volume-controlled ventilation mode and spontaneous breathing). The spontaneous breathing group showed a significantly lower post-operative pain level than the volume-controlled ventilation mode group. Furthermore, less remifentanil as well as less piritramide was needed in the spontaneous breathing group compared with volume-controlled ventilation mode. It was possible to achieve spontaneous breathing in all patients with 0.6 minimum alveolar concentration desflurane, in order to control the remifentanil rate and prevent an overdose. All spontaneous breathing patients had low intra- and post-operative pain levels and the need for analgesics was equal to or lower than that in the volume-controlled ventilation mode group. By reducing the intra-operative amount of opiates, both the post-operative pain and the amount of post-operative analgesia required can be reduced. A balanced anesthesia with spontaneous intra-operative breathing is needed to determine the required amount of opiates. This study was approved by the Ethic Committee of the Ruhr-University of Bochum (approval No. 2435) in September, 2004.

Pressure Controlled Ventilation versus Volume-Controlled Ventilation Regarding Hemodynamics and Stress Response for Posterior Lumbar Spine Surgeries in The Prone Position

Background: Prone positioning may induce alterations of airway pressures and hemodynamic that may affect intraoperative blood loss. Ventilation mode may modify these alterations. Objective: Our study aimed to differences between pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in their effects on hemodynamic changes during posterior lumbar surgeries performed in the prone position. Patients and Methods: This is a prospective randomized controlled study, which was performed in the Department of Anaesthesiology and Surgical ICU, Aswan university, Egypt at the duration from 1-6-2017 to 13-12-2018 for 60 patients who had posterior lumbar spine surgery in prone position who were eligible to inclusion/exclusion criteria divided into two groups; Group (I) were received VCV mode (n = 30) and Group (II) were received PCV mode (n = 30) then study parameters were recorded intraoperatively and postoperatively in the two groups of ventilation modes. Results: As regarding heart rate, mean arterial blood pressure, serum glucose level, and serum cortisol level, they were statistically significantly lower in PCV group than VCV group both intraoperative and postoperative which reflects that stress response is lower with PCV more than VCV and that may have also a rule in decreasing intraoperative blood loss and improving the surgical field in these surgeries. Conclusions: for lumbar spine surgeries in the prone position, PCV was associated with decreased HR, blood pressure, cortisol, glucose levels compared with VCV. The stress response is lesser with PCV which is better for this type of patients.

Pressure Controlled Ventilation versus Volume-Controlled Ventilation Regarding Hemodynamics and Stress Response for Posterior Lumbar Spine Surgeries in The Prone Position

Background: Prone positioning may induce alterations of airway pressures and hemodynamic that may affect intraoperative blood loss. Ventilation mode may modify these alterations. Objective: Our study aimed to differences between pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in their effects on hemodynamic changes during posterior lumbar surgeries performed in the prone position. Patients and Methods: This is a prospective randomized controlled study, which was performed in the Department of Anaesthesiology and Surgical ICU, Aswan university, Egypt at the duration from 1-6-2017 to 13-12-2018 for 60 patients who had posterior lumbar spine surgery in prone position who were eligible to inclusion/exclusion criteria divided into two groups; Group (I) were received VCV mode (n = 30) and Group (II) were received PCV mode (n = 30) then study parameters were recorded intraoperatively and postoperatively in the two groups of ventilation modes. Results: As regarding heart rate, mean arterial blood pressure, serum glucose level, and serum cortisol level, they were statistically significantly lower in PCV group than VCV group both intraoperative and postoperative which reflects that stress response is lower with PCV more than VCV and that may have also a rule in decreasing intraoperative blood loss and improving the surgical field in these surgeries. Conclusions: for lumbar spine surgeries in the prone position, PCV was associated with decreased HR, blood pressure, cortisol, glucose levels compared with VCV. The stress response is lesser with PCV which is better for this type of patients.