Simulated ventilation of two patients with a single ventilator in a pandemic setting

Simultaneous ventilation of two patients may lead to hypoventilation in one patient and hyperinflation in the other patient. In a simulation of ventilation in two patients using artificial lungs, we voluntarily directed gas flow to one patient by using three-dimensional-printed Y-adapters and stenosis adapters during volume- and pressure-controlled ventilation in the first set up. We continuously modified the model using a special one-way valve on the flow-limited side and measured it in pressure-controlled ventilation with the flow sensor of the ventilator adjusted on both sides in a second and third setup. In the first setup, volume- or pressure-controlled ventilation resulted in comparable minute volumes in both lungs, even when one side was obstructed to 3 mm. In the second setup, with a 3-mm flow limitation, we had a minute ventilation of 9.4 ± 0.3 vs. 3.5 ± 0.1 L/min. In the third setup, ventilation with a 3-mm flow limitation resulted in minute ventilation of 7.2 ± 0.2 vs. 5.70 L/min at a compliance of 30 vs. 70 mL/mbar. It is possible to override the safety features of a modern intensive care ventilator and thus direct tidal volumes in different lung conditions to one lung using three-dimensional-printed flow limiters. While this ventilation setting was technically feasible in a bench model, it would be unstable, if not dangerous, in a clinical situation.

Nocturnal Pressure Controlled Ventilation Improves Sleep Efficiency in Patients Receiving Mechanical Ventilation

BACKGROUND

Patients receiving mechanical ventilation commonly experience sleep fragmentation. The present meta-analysis compared the effects of pressure controlled ventilation (PCV) and pressure support ventilation (PSV) on sleep quality.

METHODS

We conducted a search of the PubMed, Embase, and Cochrane Library databases for studies published before November 2023. In this meta-analysis, individual effect sizes were standardized, and the pooled effect size was determined by using random-effects models. The primary outcome was sleep efficiency. The secondary outcomes were wakefulness, percentages of REM (rapid eye movement) sleep and stages 3 and 4 non-REM sleep, the fragmentation index, and the incidence of apneic events.

RESULTS

This meta-analysis examined 4 trials that involved 67 subjects. Sleep efficiency was significantly higher in the PCV group than in the PSV group (mean difference 15.57%, 95% CI 8.54%-22.59%). Wakefulness was significantly lower in the PCV group than in the PSV group (mean difference -18.67%, 95% CI -30.29% to -7.04%). The percentage of REM sleep was significantly higher in the PCV group than in the PSV group (mean difference 2.32%, 95% CI 0.20%-4.45%). Among the subjects with a tendency to develop sleep apnea, the fragmentation index was significantly lower in those receiving PCV than PSV (mean difference -40.00%, 95% CI -51.12% to -28.88%). The incidence of apneic events was significantly lower in the PCV group than in the PSV group (risk ratio 0.06, 95% CI 0.01-0.45).

CONCLUSIONS

Compared with PSV, PCV may improve sleep quality in patients receiving nocturnal mechanical ventilation.

Position-Dependent Symptoms of Pneumothorax During Mechanical Ventilation: A Case Report

A 54-year-old male with severe hypoxia was transferred to our hospital after choking on a mochi. Chest computed tomography revealed negative pressure pulmonary edema without pneumothorax. Endotracheal intubation was performed, and pressure-controlled ventilation was initiated. Following admission to the intensive care unit, his respiratory condition was stable in both the supine and left decubitus positions. However, every time he was placed in the right decubitus position, the tidal volume decreased by half, and SpO₂ dropped rapidly to 80%, which recovered soon after returning to the supine position. Chest radiography was performed the following day, revealing grade II right pneumothorax, and a chest tube placement stabilized his respiratory status in the right decubitus position. Air leakage ceased within a few hours. Extubation was successful on the fifth hospital day, and the chest tube was removed on the eighth hospital day. To our knowledge, there are no previous reports on position-dependent symptoms of pneumothorax during mechanical ventilation. Clinicians should consider the possibility of pneumothorax on that same side when respiratory deterioration is observed only in one lateral decubitus position during mechanical ventilation.

Comparison of Effectiveness of CE Technique and Jaw Thrust Technique for Mask Ventilation on Apneic Anesthetized Adults: A Randomized Controlled Trial

Background

The two most common techniques for mask ventilation are CE and jaw thrust (JT) technique. However, few studies have validated their efficiency in terms of tidal volume (TV).

Aims

This study aimed to compare the effectiveness of the CE technique and JT technique during pressure-controlled ventilation (PCV) by the mean of returned TV on apneic anesthetized adults.

Design

This was a prospective, randomized cross over study.

Settings

This study was conducted in a tertiary care hospital.

Methods

Ethical Committee approval from our institution was taken (ss-1/EC 049/2017) and was registered in Clinical Trials Registry of India (CTRI/2018/04/012958). Sixty-five American Society of Anesthesiologists Physical Status classes I and II adult patients were enrolled in the study. After induction and muscle relaxation, mask ventilation was performed with CE and JT technique on PCV mode (Pinsp 15 cm H2O, respiratory rate 15) for 1 min each. The mean of returned TV of last 12 breaths, gastric insufflation, audible mask leak, and operator comfort in each technique were compared.

Statistical Analysis

Statistical software namely IBM SPSS 22.0 and R environment version 3.2.2 (IBM Corp. SPSS Statistics for Windows, Version 22.0. Armonk, NY, USA) were used for data analysis. Microsoft Excel was used to generate graphs and tables. Data were expressed as mean ± standard deviation for continuous variables and number (%) for categorical variables. Student's t-test (two tailed, independent) was used to find the significance of the study parameters on a continuous scale. Chi-square/Fisher's exact test was used to find the significance of the study parameters on a categorical scale between two or more groups.

Results

There was a significant increase in mean TV generated by JT technique over CE technique (591.46 ± 140.27 mL vs. 544.59 ± 159.08 mL; P < 0.001). Gastric insufflation (12.9% vs. 14.5%) and mask leak (11.3% vs. 38.7%) were more in CE technique. Operator comfort (79% vs. 19.4%) was more in JT technique.

Conclusion

A two-handed JT technique is more effective than a one-handed CE technique for mask ventilation in apneic anesthetized adults.

Comparison of Volume-Guaranteed or -Targeted, Pressure-Controlled Ventilation with Volume-Controlled Ventilation during Elective Surgery: A Systematic Review and Meta-Analysis

For perioperative mechanical ventilation under general anesthesia, modern respirators aim at combining the benefits of pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV) in modes typically named “volume-guaranteed” or “volume-targeted” pressure-controlled ventilation (PCV-VG). This systematic review and meta-analysis tested the hypothesis that PCV-VG modes of ventilation could be beneficial in terms of improved airway pressures (P_peak, P_plateau, P_mean), dynamic compliance (C_dyn), or arterial blood gases (P_aO₂, P_aCO₂) in adults undergoing elective surgery under general anesthesia. Three major medical electronic databases were searched with predefined search strategies and publications were systematically evaluated according to the Cochrane Review Methods. Continuous variables were tested for mean differences using the inverse variance method and 95% confidence intervals (CI) were calculated. Based on the assumption that intervention effects across studies were not identical, a random effects model was chosen. Assessment for heterogeneity was performed with the χ² test and the I² statistic. As primary endpoints, P_peak, P_plateau, P_mean, C_dyn, P_aO₂, and P_aCO₂ were evaluated. Of the 725 publications identified, 17 finally met eligibility criteria, with a total of 929 patients recruited. Under supine two-lung ventilation, PCV-VG resulted in significantly reduced P_peak (15 studies) and P_plateau (9 studies) as well as higher C_dyn (9 studies), compared with VCV [random effects models; P_peak: CI −3.26 to −1.47; p < 0.001; I² = 82%; P_plateau: −3.12 to −0.12; p = 0.03; I² = 90%; C_dyn: CI 3.42 to 8.65; p < 0.001; I² = 90%]. For one-lung ventilation (8 studies), PCV-VG allowed for significantly lower P_peak and higher P_aO₂ compared with VCV. In Trendelenburg position (5 studies), this effect was significant for P_peak only. This systematic review and meta-analysis demonstrates that volume-targeting, pressure-controlled ventilation modes may provide benefits with respect to the improved airway dynamics in two- and one-lung ventilation, and improved oxygenation in one-lung ventilation in adults undergoing elective surgery.

Respiratory Support of Infants With Congenital Diaphragmatic Hernia

Optimisation of respiratory support of infants with congenital diaphragmatic hernia (CDH) is critical. Infants with CDH often have severe lung hypoplasia and abnormal development of their pulmonary vasculature, leading to ventilation perfusion mismatch. It is vital that lung protective ventilation strategies are employed during both initial stabilisation and post-surgical repair to avoid ventilator induced lung damage and oxygen toxicity to prevent further impairment to an already diminished gas-exchanging environment. There is a lack of robust evidence for the routine use of surfactant therapy during initial resuscitation of infants with CDH and thus administration cannot be recommended outside clinical trials. Additionally, inhaled nitric oxide has been shown to have no benefit in reducing the mortality rates of infants with CDH. Other therapeutic agents which beneficially act on pulmonary hypertension are currently being assessed in infants with CDH in randomised multicentre trials. The role of novel ventilatory modalities such as closed loop automated oxygen control, liquid ventilation and heliox therapy may offer promise for infants with CDH, but the benefits need to be determined in appropriately designed clinical trials.

The effects of one-lung ventilation mode on lung function in elderly patients undergoing esophageal cancer surgery

The objective of the present study was to explore the effects of different one-lung ventilation (OLV) modes on lung function in elderly patients undergoing esophageal cancer surgery. A total of 180 consecutive elderly patients (ASA Grades I-II, with OLV indications) undergoing elective surgery were recruited in the study. Patients were randomly divided into 4 groups (n = 45). In Group A, patients received low tidal volume (VT < 8 mL/kg) + pressure controlled ventilation (PCV), low tidal volume (VT < 8 mL/kg) + volume-controlled ventilation (VCV) in Group B, high tidal volume (VT ≥ 8 mL/kg) + PCV in Group C and high tidal volume (VT ≥ 8 mL/kg) + VCV in Group D. Two-lung ventilation involved routine tidal volume (8-10 mL/kg) at a frequency of 12 to 18 times/min, and VCV mode. Clinical efficacy among 4 groups was compared. The partial pressure of end-tidal carbon dioxide (PetCO2) did not significantly differ among 4 groups (all P > .05), and the oxygenation index and SO2 in Group A were significantly higher than in the other groups (P < .05). The PetCO2, peak airway pressure (Ppeak), platform airway pressure (Pplat), and mean airway pressure (Pmean) in Group A were significantly lower than those in the other groups (all P < .05). However, airway resistance (Raw) among 4 groups did not significantly differ (all P > .05). The incidence of pulmonary infection, anastomotic fistula, ventilator-induced lung injury, lung dysfunction, difficulty weaning from mechanical ventilation, and multiple organ dysfunction in Groups A and B were lower than that in Groups C and D (all P < .05). The expression levels of IL-6, tumor necrosis factor-α, and C-reactive protein in lavage fluid in Group A were significantly lower than those in the other groups (all P < .05). OLV with low tidal volume (VT < 8 mL/kg) + PCV (5 cmH2O PEEP) improved lung function and mitigated inflammatory responses in elderly patients undergoing esophageal cancer surgery.

The Effect of Pressure-Controlled Ventilation and Volume-Controlled Ventilation in Prone Position on Pulmonary Mechanics and Inflammatory Markers

The aim of this present study is to compare the effect of pressure-controlled ventilation and volume-controlled ventilation on pulmonary mechanics and inflammatory markers in prone position. The study included 41 patients undergoing to vertebrae surgery. The patients were randomized into two groups: Group 1 received volume-controlled ventilation, while group 2 received pressure-controlled ventilation. The demographic data, pulmonary mechanics, the inflammatory marker levels just after the induction of anesthetics, at the 6th and 12th hours, and gas analysis from arterial blood samples taken at the beginning and the 30th minute were recorded. The inflammatory marker levels increased in both groups, without any significant difference among groups. Peak inspiratory pressure level was higher in the volume-controlled ventilation group. This study revealed that there is no difference regarding inflammatory marker levels between volume- and pressure-controlled ventilation.

Ventilation of Nonparalyzed Patients Under Anesthesia with Laryngeal Mask Airway, Comparison of Three Modes of Ventilation: Volume Controlled Ventilation, Pressure Controlled Ventilation, and Pressure Controlled Ventilation-volume Guarantee

BACKGROUND

Pressure controlled ventilation (PCV) is the preferable mode of ventilation of nonparalyzed patients undergoing anesthesia with laryngeal mask airway (LMA) as compared to volume controlled ventilation (VCV) and spontaneously breathing patient. In this study, we compared the PC-volume guarantee (PC-VG) mode of ventilation with VCV and PCV modes.

MATERIALS AND METHODS

A total of 30 patients, American Society of Anesthesiologists (ASA) physical status Classes I and II, scheduled for elective surgery under general anesthesia with a classic LMA were ventilated, subsequently, with the three modes of ventilation: VCV, PCV, and PC-VG for 10 min each mode. Tidal volume set for all patients was 8 ml/kg of ideal body weight. Parameters measured with modes of ventilation include peak inspiratory pressure (PIP), compliance, measured tidal volume, O₂ saturation, end-tidal CO₂, and presence of an oropharyngeal leak.

RESULTS

The PIP was significantly higher with the application of VCV mode of ventilation than PCV and PC-VG modes. The compliance was significantly lower when using the mode of ventilation VCV than PCV and PC-VG. The PIP and the compliance were not statistically different between the PCV and PC-VG modes of ventilation.

CONCLUSIONS

Ventilation of nonparalyzed patients with LMA under anesthesia with PC-VG is advantageous over VCV in reducing PIP and increasing lung compliance. No difference was noted between PCV and PC-VG in ASA Classes I or II under the adequate depth of anesthesia in patients with normal pulmonary function.

Comparison of volume controlled ventilation and pressure controlled ventilation in patients undergoing robot-assisted pelvic surgeries: An open-label trial

Background and Aims:

Although volume controlled ventilation (VCV) has been the traditional mode of ventilation in robotic surgery, recently pressure controlled ventilation (PCV) has been used more frequently. However, evidence on whether PCV is superior to VCV is still lacking. We intended to compare the effects of VCV and PCV on respiratory mechanics and haemodynamic in patients undergoing robotic surgeries in steep Trendelenburg position.

Methods:

This prospective, randomized trial was conducted on sixty patients between 20 and 70 years belonging to the American Society of Anesthesiologist Physical Status I–II. Patients were randomly assigned to VCV group (n = 30), where VCV mode was maintained through anaesthesia, or the PCV group (n = 30), where ventilation mode was changed to PCV after the establishment of 40° Trendelenburg position and pneumoperitoneum. Respiratory (peak and mean airway pressure [AP_peak, AP_mean], dynamic lung compliance [C_dyn] and arterial blood gas analysis) and haemodynamics variables (heart rate, mean blood pressure [MBP] central venous pressure) were measured at baseline (T₁), post-Trendelenburg position at 60 min (T₂), 120 min (T₃) and after resuming supine position (T₄).

Results:

Demographic profile, haemodynamic variables, oxygen saturation and minute ventilation (MV) were comparable between two groups. Despite similar values of AP_mean, AP_peak was significantly higher in VCV group at T2 and T3 as compared to PCV group (P < 0.001). C_dyn and PaCO₂ were also better in PCV group than in VCV group (P < 0.001 and 0.045, respectively).

Conclusion:

PCV should be preferred in robotic pelvic surgeries as it offers lower airway pressures, greater C_dyn and a better-preserved ventilation-perfusion matching for the same levels of MV.

[The effects of pressure controlled ventilation for tracheobronchial foreign body removal in children]

Objective:To evaluate the effects of pressure controlled ventilation for tracheobronchial foreign body removal in children.Method: Ninety ASAⅡor Ⅲ children,aged 10 months to 3 yr,weighing 8-16 kg undergoing removal of airway foreign body were randomly divided into 3 groups(n=30 each):groupⅠpressure controlled ventilation(P)，group Ⅱ high-frequency jet ventilation(H),and group Ⅲ, reserve spontaneously breathings.Arterial blood gas analysis of Pre-operation and the end of operation,the occurrence of hypoxia during operation,the duration of operation,anesthesia emergence time and perioperative side effects were recorded. Result:The arterial blood gas analysis(PaO₂,PaCO₂,SaO₂)and SPO₂of Pre-operation in group P and H had no significant difference. The PaO₂ of the end of operations was significantly higher,and PaCO₂ was lower in group H. The occurrence of hypoxia during operation, the duration of operation,anesthesia emergence time and perioperative side effects in two group had no significant difference.Conclusion:The effects of pressure controlled ventilation and high-frequency jet ventilation for tracheobronchial foreign body removal in children were nearly the same,and pressure controlled ventilation can be commonly used in clinic.

Comparison of three ventilatory modes during one-lung ventilation in elderly patients

OBJECTIVE

The purpose of this study was to explore the effects of three different ventilatory modes: volume controlled ventilation (VCV), pressure controlled ventilation (PCV) and pressure controlled ventilation-volume guaranteed (PCV-VG) on arterial oxygenation and airway pressure during one-lung ventilation (OLV) in elderly patients.

METHODS

We enrolled 66 patients who underwent thoracic surgery requiring at least 1 hour of OLV and aged above 65 years into the study. Patients were classified into VCV, PCV and PCV-VG groups according to a controlled, randomized design. Patients were ventilated to obtain a tidal volume (TV) of 8 mL/kg with three different ventilatory modes during OLV. The Hemodynamic and respiratory data had been recorded during intraoperation and arterial blood gases were obtained at baseline, 20, 40, 60 minutes after OLV, end of surgery.

RESULTS

Compared with VCV group, Ppeak was significantly lower in PCV and PCV-VG group (P<0.05), and the difference was not found between the PCV and PCV-VG group. PaO2 in PCV and PCV-VG group were higher than VCV group after the point of OLV+40 (P<0.05). Comparison of PCV group, PaO2 in PCV-VG group was higher, but did not show a significantly improved during OLV (P>0.05).

CONCLUSIONS

Compared with VCV, the use of PCV and PCV-VG have a significant advantage in intraoperative oxygenation and airway pressure for eldly patients undergoing OLV.