BACKGROUND: There is a high incidence of pulmonary atelectasis during paediatric laparoscopic surgeries. The authors hypothesised that utilising a recruitment manoeuvre or using continuous positive airway pressure may prevent atelectasis compared to conventional ventilation.
OBJECTIVE: The primary objective was to compare the degree of lung atelectasis diagnosed by lung ultrasound (LUS) using three different ventilation techniques in children undergoing laparoscopic surgeries.
METHODS: Randomised, prospective three-arm trial.
METHODS: Single institute, tertiary care, teaching hospital.
METHODS: Children of ASA PS 1 and 2 up to the age of 10 years undergoing laparoscopic surgery with pneumoperitoneum lasting for more than 30 min.
METHODS: Random allocation to one of the three study groups: CG group: Inspiratory pressure adjusted to achieve a TV of 5-8 ml/kg, PEEP of 5 cm H2O, respiratory rate adjusted to maintain end-tidal carbon dioxide (ETCO2) between 30-40 mm Hg with manual ventilation and no PEEP at induction. RM group: A recruitment manoeuvre of providing a constant pressure of 30 cm H2O for ten seconds following intubation was applied. A PEEP of 10 cm H2O was maintained intraoperatively. CPAP group: Intraoperative maintenance with PEEP 10 cm H2O with CPAP of 10 cm H2O at induction using mechanical ventilation was done.
METHODS: Lung atelectasis score at closure assessed by LUS.
RESULTS: Post induction, LUS was comparable in all three groups. At the time of closure, the LUS for the RM group (8.6 ± 4.9) and the CPAP group (8.8 ± 6.8) were significantly lower (p < 0.05) than the CG group (13.3 ± 3.8). In CG and CPAP groups, the score at closure was significantly higher than post-induction. The PaO2/FiO2 ratio was significantly higher (p < 0.05) for the RM group (437.1 ± 44.9) and CPAP group (421.6 ± 57.5) than the CG group (361.3 ± 59.4) at the time of pneumoperitoneum.
CONCLUSIONS: Application of a recruitment manoeuvre post-intubation or CPAP during induction and maintenance with a high PEEP leads to less atelectasis than conventional ventilation during laparoscopic surgery in paediatric patients.
BACKGROUND: CTRI/2019/08/02058.

Many RCTs have evaluated the influence of intraoperative tidal volume (tV), PEEP, and driving pressure on the occurrence of postoperative pulmonary complications, cardiovascular complications, and mortality in adult patients. Our meta-analysis aimed to investigate the association between tV, PEEP, and driving pressure and the above-mentioned outcomes.
We conducted a systematic review and meta-analysis of RCTs from inception to May 19, 2022. The primary outcome was the incidence of postoperative pulmonary complications; the secondary outcomes were intraoperative cardiovascular complications and 30-day mortality. Primary and secondary outcomes were evaluated stratifying patients in the following groups: (1) low tV (LV, tV 6-8 ml kg-1 and PEEP ≥5 cm H2O) vs high tV (HV, tV >8 ml kg-1 and PEEP=0 cm H2O); (2) higher PEEP (HP, ≥6 cm H2O) vs lower PEEP (LP, <6 cm H2O); and (3) driving pressure-guided PEEP (DP) vs fixed PEEP (FP).
We included 16 RCTs with a total sample size of 4993. The incidence of postoperative pulmonary complications was lower in patients treated with LV than with HV (OR=0.402, CI 0.280-0.577, P<0.001) and lower in DP than in FP group (OR=0.358, CI 0.187-0.684, P=0.002). Postoperative pulmonary complications did not differ between HP and LP groups; the incidence of intraoperative cardiovascular complications was higher in HP group (OR=1.385, CI 1.027-1.867, P=0.002). The 30-day mortality was not influenced by the ventilation strategy.
Optimal intraoperative mechanical ventilation is unclear; however, our meta-analysis showed that low tidal volume and driving pressure-guided PEEP strategies were associated with a reduction in postoperative pulmonary complications.

Evidence suggests that ventilation during ex vivo lung perfusion (EVLP) with a \'one-size-fits-all\' strategy has the potential to cause lung injury which may only become clinically relevant in marginal lung allografts. EVLP induced- or accelerated lung injury is a dynamic and cumulative process reflecting the interplay of a number of factors. Stress and strain in lung tissue caused by positive pressure ventilation may be exacerbated by the altered properties of lung tissue in an EVLP setting. Any pre-existing injury may alter the ability of lung allografts to accommodate set ventilation and perfusion techniques on EVLP leading to further injury. This review will examine the effects of ventilation on donor lungs in the setting of EVLP. A framework for developing a protective ventilation technique will be proposed.

Under the global landscape of the prolonged COVID-19 pandemic, the number of individuals who need to be tested for COVID-19 through screening centers is increasing. However, the risk of viral infection during the screening process remains significant. To limit cross-infection in screening centers, a non-contact mobile screening center (NCMSC) that uses negative pressure booths to improve ventilation and enable safe, fast, and convenient COVID-19 testing is developed. This study investigates aerosol transmission and ventilation control for eliminating cross-infection and for rapid virus removal from the indoor space using numerical analysis and experimental measurements. Computational fluid dynamics (CFD) simulations were used to evaluate the ventilation rate, pressure differential between spaces, and virus particle removal efficiency in NCMSC. We also characterized the airflow dynamics of NCMSC that is currently being piloted using particle image velocimetry (PIV). Moreover, design optimization was performed based on the air change rates and the ratio of supply air (SA) to exhaust air (EA). Three ventilation strategies for preventing viral transmission were tested. Based on the results of this study, standards for the installation and operation of a screening center for infectious diseases are proposed.

Controversy surrounds regional cerebral oximetry (rSO2) because extracranial contamination and unmeasured changes in cerebral arterial:venous ratio confound readings. Correlation of rSO2 with brain tissue oxygen (PbrO2), a \"gold standard\" for cerebral oxygenation, could help resolve this controversy but PbrO2 measurement is highly invasive. This was a prospective cohort study. The primary aim was to evaluate correlation between PbrO2 and rSO2 and the secondary aim was to investigate the relationship between changing ventilation regimens and measurement of PbrO2 and rSO2. Patients scheduled for elective removal of cerebral metastases were anesthetized with propofol and remifentanil, targeted to a BIS range 40-60. rSO2 was measured using the INVOS 5100B monitor and PbrO2 using the Licox brain monitoring system. The Licox probe was placed into an area of normal brain within the tumor excision corridor. FiO2 and minute ventilation were sequentially adjusted to achieve two set points: (1) FiO2 0.3 and paCO2 30 mmHg, (2) FiO2 1.0 and paCO2 40 mmHg. PbrO2 and rSO2 were recorded at each. Nine participants were included in the final analysis, which showed a positive Spearman\'s correlation (r = 0.50, p = 0.036) between PbrO2 and rSO2. From set point 1 to set point 2, PbrO2 increased from median 6.0, IQR 4.0-11.3 to median 22.5, IQR 9.8-43.6, p = 0.015; rSO2 increased from median 68.0, IQR 62.5-80.5 to median 83.0, IQR 74.0-90.0, p = 0.047. Correlation between PbrO2 and rSO2 is evident. Increasing FiO2 and PaCO2 results in significant increases in cerebral oxygenation measured by both monitors.

If noninvasive ventilation (NIV or high-flow CPAP) fails in severe cases of COVID-19, escalation of treatment with orotracheal intubation and intermitted prone positioning is provided as standard care. The present case reports show two COVID-19 patients with severe refractory hypoxemia despite NIV treatment during the first wave (first half year 2020) and the resulting influence on the treatment regimen during the second wave (since October 2020) of the pandemic. Both patients (aged 63 years and 77 years) voluntarily positioned themselves on the side or in a prone position without prior sedation and oral intubation. Positional treatment promptly improved the arterial oxygenation level. The oxygenation index improved in the following days with continued NIV and intermittent prone and side position. The recovered patients were transferred from the intensive care unit at days 5 and 14, respectively after admission. The case reports, along with other reports, show that prone or lateral positioning may be important in the treatment of SARS-CoV‑2 pneumonia in awake and not yet intubated patients.
UNASSIGNED: Schwere Verläufe von COVID-19 führen bei Versagen einer unterstützenden nichtinvasiven Beatmung („high flow“, CPAP bzw. NIV) zur Eskalation der Therapie mit orotrachealer Intubation und anschließender Bauchlagerung. In dem vorliegenden Fallbericht werden zwei COVID-19-Patienten mit schwerer refraktärer Hypoxämie unter eskalierter nichtinvasiver Beatmungstherapie aus der ersten Pandemiewelle (erstes Halbjahr 2020) sowie das dadurch beeinflusste Vorgehen in der zweiten Pandemiewelle (seit 10/2020) vorgestellt. Beide Patienten (Alter: 63 und 77 Jahre) lagerten sich bereits vor Indikationsstellung einer Intubation selbstständig auf die Seite bzw. auf dem Bauch, was zu einer prompten Verbesserung der Oxygenierung führte. Die Oxygenierungsstörung verbesserte sich unter regelmäßiger Lagerungstherapie und NIV in den folgenden Tagen, sodass die Patienten nach 5 bzw. 14 Tagen von der Intensivstation verlegt werden konnten. Der Fallbericht zeigt zusammen mit anderen Berichten, dass eine Bauch- oder Seitenlagerung bei wachen, noch nicht intubierten Patienten einen wichtigen Stellenwert bei der Behandlung einer SARS-CoV-2-Pneumonie haben könnte.

Prefabricated inpatient wards have been proven to be an efficient alternative to quickly extend the caring capacity for patients. In this study, three typical ventilation strategies were studied using computational fluid dynamics in a prefabricated Coronavirus disease 2019 double-patient ward. Pollutants are the respiratory droplets and aerosols injected from two manikins. They are modelled as particles with different diameters (3 μm, 6 μm, 12 μm, 20 μm, 45 μm and 175 μm) by the Eulerian-Lagrangian model. Three ventilation strategies with an identical air change rate of 12.3 h-1 but different layouts of inlets and outlets are implemented. The flow field, flow structures and particle trajectories have been analysed and compared among the three ventilation strategies. The fate of particles is analysed and compared quantitatively. It is found that small particles (<20 μm) can move along with the main flow streams. Most of them are removed by ventilation to the outlet(s). Large particles (>45 μm) cannot move with the flow streams over a long path. Most of them deposit on solid surfaces in different regions of the ward in each ventilation strategy. Health workers should pay close attention to these polluted areas. Targeted cleaning of the polluted areas is necessary in a prefabricated inpatient ward. To promote the removal of some large particles (e.g., 45 μm) by the outlet(s), the outlet(s) should be installed inside the landing area of large particles and close to the polluted source(s).

Postoperative pulmonary complications are common after cardiac surgery and have been related to lung collapse during cardiopulmonary bypass (CPB). No consensus exists regarding the effects of maintaining mechanical ventilation during CPB to decrease these complications.
To determine whether maintaining low-tidal ventilation (3 mL/kg 5 times/min, with positive end expiratory pressure of 5 cm H2O) during CPB (ventilation strategy) was superior to a resting-lung strategy with no ventilation (no ventilation strategy) regarding postoperative pulmonary complications, including mortality.
In a randomized controlled trial, patients undergoing cardiac surgery at a single center from May 2017 through August 2019 were randomized to the ventilation or no ventilation strategy during CPB (1:1 ratio). Apart from the CPB phase, perioperative ventilation procedures were standardized.
The study included 1,501 patients (mean age, 68.8 ± 10.3 years; 1,152 (76.7%) men; mean EuroSCORE II, 2.3 ± 2.7). Seven hundred fifty-six patients were in the ventilation strategy group, and no differences existed in baseline characteristics and types of procedures between the two groups. An intention-to-treat analysis yielded no significant difference between the ventilation and no ventilation groups regarding incidence of the primary composite outcome combining death, early respiratory failure, ventilation support beyond day 2, and reintubation, with 112 of 756 patients (14.8%) in the ventilation group vs 133 of 745 patients (17.9%) in the no ventilation group (OR, 0.80; 95% CI, 0.61-1.05; P = .11). Strict per-protocol analyses of 1,338 patients (89.1%) with equally distributed preoperative characteristics yielded similar results (OR, 0.81; 95% CI, 0.60-1.09; P = .16). Post hoc analysis of the subgroup who underwent isolated coronary artery bypass graft procedures (n = 725) showed that the ventilation strategy was superior to the no ventilation strategy regarding the primary outcome (OR, 0.56; 95% CI, 0.37-0.84; P = .005).
Among patients undergoing cardiac surgery with CPB, continuation of low tidal volume ventilation was not superior to no ventilation during CPB with respect to postoperative complications, including death, early respiratory failure, ventilation support beyond day 2, and reintubation.
ClinicalTrials.gov; No.: NCT03098524; URL: www.clinicaltrials.gov.

As per current guidelines, whenever an advanced airway is in place during cardiopulmonary resuscitation, positive pressure ventilation should be provided without pausing for chest compression. Positive pressure ventilation can be provided through bag-valve resuscitator (BV) or mechanical ventilator (MV), which was found to be equally efficacious. In a busy emergency department, with less trained personnel use of MV is advantageous over BV in terms of reducing human errors and relieving the airway manager to focus on other resuscitation tasks. Currently, there are no guidelines specific to MV settings in cardiac arrest. We present a concept of \"six-dial ventilator strategy during CPR\" that encompasses the evidence-based settings appropriate during chest compression. We suggest use of volume control ventilation with the following settings: (1) positive end-expiratory pressure of 0 cm of water (to allow venous return), (2) tidal volume of 8 mL/kg with fraction of inspired oxygen at 100% (for adequate oxygenation), (3) respiratory rate of 10 per minute (for adequate ventilation), (4) maximum peak inspiratory pressure or P max alarm of 60 cm of water (to allow tidal volume delivery during chest compression), (5) switching OFF trigger (to avoid trigger by chest recoil), and (6) inspiratory to expiratory time ratio of 1:5 (to provide adequate inspiratory time of 1 second). How to cite this article: Sahu AK, Timilsina G, Mathew R, Jamshed N, Aggarwal P. \"Six-dial Strategy\"-Mechanical Ventilation during Cardiopulmonary Resuscitation. Indian J Crit Care Med 2020;24(6):487-489.

This paper investigated the transmission of respiratory droplets between two seated occupants equipped with one type of personalized ventilation (PV) device using round movable panel (RMP) in an office room. The office was ventilated by three different total volume (TV) ventilation strategies, i.e. mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD) system respectively as background ventilation methods. Concentrations of particles with aerodynamic diameters of 0.8 μm, 5 μm, and 16 μm as well as tracer gas were numerically studied in the Eulerian frame. Two indexes, i.e. intake fraction (IF) and concentration uniformity index R C were introduced to evaluate the performance of ventilation systems. It was found that without PV, DV performed best concern protecting the exposed manikin from the pollutants exhaled by the polluting manikin. In MV when the exposed manikin opened RMP the inhaled air quality could always be improved. In DV and UFAD application of RMP might sometimes, depending on the personalized airflow rate, increase the exposure of the others to the exhaled droplets of tracer gas, 0.8 μm particles, and 5 μm particles from the infected occupants. Application of PV could reduce R C for all the three TV systems of 0.8 μm and 5 μm particles. PV enhanced mixing degree of particles under DV and UFAD based conditions much stronger than under MV based ones. PV could increase the average concentration in the occupied zone of the exposed manikin as well as provide clean personalized airflow. Whether inhaled air quality could be improved depended on the balance of pros and cons of PV.