Peak Inspiratory Pressure Research Articles

Innovative Use of High-Fidelity Lung Simulators to Test a Ventilator Splitter Device.

The coronavirus disease 2019 (COVID-19) pandemic has rapidly exposed health care system inadequacies. Hospital ventilator shortages in Italy compelled US physicians to consider creative solutions, such as using Y-pieces or T-pieces, to preclude the need to make decisions of life or death based on medical equipment availability. We add to current knowledge and testing capacity for ventilator splitters by reporting the ability to examine the functionality of ventilator splitters by using 2 high-fidelity lung simulators. Data obtained by the high-fidelity lung simulators included: tidal volume, respiratory rate, minute ventilation, peak inspiratory pressure, peak plateau pressure, and positive end-expiratory pressure.

Accuracy of volume and pressure delivery by mechanical ventilators in use in neonatal intensive care units: A quality control study.

Despite technical specifications of neonatal mechanical ventilators (MVs) guarantee clinically irrelevant discrepancies between the set and the delivered values of ventilation parameters, previous studies reported large deviations. Most studies characterized performances of a given model/brand by studying a single device, disregarding possible intramodel differences, and leaving the accuracy of the ventilation parameters effectively delivered in clinical settings unknown. The aim of this study was to evaluate the real-life accuracy of pressure and volume parameters delivered by neonatal ventilators ready to be used on patients in neonatal intensive care units (NICUs). In vitro study. Neonatal ventilators (n = 33 of 8 different models) available in four European NICUs. The MVs were connected to a test lung (resistance = 50 cmH2 O*s/L, compliance = 0.35 mL/cmH2 O) provided with pressure and flow sensors. MVs were tested over two different ventilation modes randomly: (a) pressure controlled (PC) with a peak inspiratory pressure (PIP) of 22 cmH2 O, and (b) PC with volume targeted ventilation (VTV) with a tidal volume (VT ) of 6 mL. In all tests, positive end-expiratory pressure (PEEP) was set to 6 cmH2 O, respiratory rate to 45 breaths/min, inspiratory time to 0.33 seconds, and oxygen fraction to 0.3. During PC the median (min-max) values delivered were: PEEP = 5.84(4.95-6.48) cmH2 O, PIP = 21.63(20.04-22.62) cmH2 O. During VTV, VT was 5.94(4.63-8.01) mL. VT was considerably variable, ranging from -22% to +33% of the set and displayed values. Differences in accuracy among devices of the same model were comparable to those found among different models. Our findings suggest that loss of accuracy in ventilation variables is likely related to daily use of the devices rather than weakness in the design or manufacturing process, urging the improvement of maintenance and quality control procedures to preserve the performances of neonatal MVs during their entire lifespan.

Changes in Electrical Activity of the Diaphragm in Response to Painful Procedures in Neonates

Background: Premature neonates are exposed to numerous painful procedures. Physiologic fluctuations in heart rate (HR), respiratory rate, and oxygen saturation are typically used to determine the response to pain. Neurally assisted ventilatory assist (NAVA) delivers inspiratory pressure in proportion to the electrical activity of the diaphragm (Edi). Since NAVA allows self-regulation of peak inspiratory pressures (PIP), there is apprehension that painful stimulus may increase respiratory drive and result in ex- cessive PIP. This study evaluated changes in respiratory drive, measured by Edi, in response to a painful procedure (heel stick) to determine if there was excessive PIP delivered from the ventilator. Methods: Prospective, single-center study; subjects <32 weeks on NAVA/NIV NAVA requiring routine blood work via heel sticks. Vital signs were measured every 10 seconds for the first 2 minutes. PIP, Edi peak, and min were collected for the first ten breaths and then averaged at 1 and 2 minutes. Statistics were repeated measures ANOVA. Results: Fourteen subjects with gestational age 26.9+2 weeks and birth weight 994+318 grams. At study, the average age was 4.6+5 days, and weight was 948+305 grams. Following the heel stick, the first breath showed an increase in PIP and Edi peak but returned to baseline by the second breath. PIP increased again by the10th breath and at 1 and 2 minutes. HR increased after heel stick and remained elevated through the remainder of the study. There were no changes in tonic Edi, Edi min or other vital signs. Conclusion: Although the increase in PIP and Edi peak in response to heel stick pain was brief and limited, it is important always to set the PIP alarm limit appropriately to protect the lung from excessive pressures that may be generated during painful procedures.

Tracheobronchial Slough, a Potential Pathology in Endotracheal Tube Obstruction in Patients With Coronavirus Disease 2019 (COVID-19) in the Intensive Care Setting.

Background:A novel coronavirus (COVID-19) erupted in the latter part of 2019. The virus, SARS-CoV-2 can cause a range of symptoms ranging from mild through fulminant respiratory failure. Approximately 25% of hospitalized patients require admission to the intensive care unit, with the majority of those requiring mechanical ventilation. High density consolidations in the bronchial tree and in the pulmonary parenchyma have been described in the advanced phase of the disease. We noted a subset of patients who had a sudden, significant increase in peak airway, plateau and peak inspiratory pressures. Partial or complete ETT occlusion was noted to be the culprit in the majority of these patients.Methods:With institutional IRB approval, we examined a subset of our mechanically ventilated COVID-19 patients. All of the patients were admitted to one of our COVID-19 ICUs. Each was staffed by a board certified intensivist. During multidisciplinary rounds, all arterial blood gas (ABG) results, ventilator settings and ventilator measurements are discussed and addressed. ARDSNet Protocols are employed. In patients with confirmed acute occlusion of the endotracheal tube (ETT), acute elevation in peak airway and peak inspiratory pressures are noted in conjunction with desaturation. Data was collected retrospectively and demographics, ventilatory settings and ABG results were recorded.Results:Our team has observed impeded ventilation in intubated patients who are several days into the critical course. Pathologic evaluation of the removed endotracheal tube contents from one of our patients demonstrated a specimen consistent with sloughed tracheobronchial tissues and inflammatory cells in a background of dense mucin. Of 110 patients admitted to our adult COVID-19 ICUs, 28 patients required urgent exchange of their ETT.Conclusion:Caregivers need to be aware of this pathological finding, recognize, and to treat this aspect of the COVID-19 critical illness course, which is becoming more prevalent.

Anesthesia in Morgagni hernia with high PIP: A case report

Morgagni hernia, a congenital diaphragmatic hernia, is usually asymptomatic. Surgery should be planned as soon as possible after diagnosis. The observation of variable degrees of pulmonary dysplasia and increased vascular resistance, and the presence of heart or other organ disorders make anesthesia management important. We describe the anesthetic management of a 2.5-month-old patient operated due to Morgagni hernia. Following intubation, peak inspiratory pressure was high, but rapidly returned to normal levels after the abdomen was opened. No complications were observed during this process in terms of anesthesia management.

Factors Affecting Survival in Congenital Diaphragmatic Hernia: A Prospective Study at a Tertiary Center

Background: The outcome of congenital diaphragmatic hernia depends on associated anomalies, degree of pulmonary hypoplasia, and hypertension. We evaluated the postnatal prognostic factors which can be used to predict the outcome.Methods: This study was conducted at a tertiary center (Vali-e-Asr Hospital, Imam Khomeini Complex, Tehran, Iran) during 2013-2019. The predictors of survival were evaluated.Results: A total of 49 infants with congenital diaphragmatic hernia were born during 2013-2019. The patients’ mean gestational age and weight at birth were 37.51±1.75 weeks and 2871±562 g, respectively. The mortality rate in patients with surgery (n = 41) was 31.3% and eight patients died before surgery. Mortality had significant relationships with five-minute Apgar score, peak inspiratory pressure before and after surgery, partial pressure of arterial oxygen (PaO2), and pH during first 24 hours after birth (p= 0.01, 0.001, and 0.01, respectively). The predicted and true survival rates in the patients were 66% and 52%, respectively (p= 0.001).Conclusion: Predicting survival rate after birth is remarkable but controversial. This estimate should not affect patient care and should only help parents in the process of decision-making.

Shared Ventilation in the Era of COVID-19: A Theoretical Consideration of the Dangers and Potential Solutions.

The use of shared ventilation, or the simultaneous support of multiple patients connected in parallel to a single mechanical ventilator, is receiving considerable interest for addressing the severe shortage of mechanical ventilators available during the novel coronavirus pandemic (COVID-19). In this paper we highlight the potentially disastrous consequences of naïve shared ventilation, in which patients are simply connected in parallel to a ventilator without any regard to their individual ventilatory requirements. We then examine possible approaches for individualization of mechanical ventilation, using modifications to the breathing circuit that may enable tuning of individual tidal volumes and driving pressures during either volume-controlled ventilation (VCV) or pressure-controlled ventilation (PCV). Breathing circuit modifications included a PEEP valve on each expiratory limb for both VCV and PCV, an adjustable constriction and one-way valve on the inspiratory limb for VCV, and a pressure-relief valve for peak inspiratory pressure reduction on the inspiratory limb for PCV. The ability to regulate individual tidal volumes using these breathing circuit modifications was tested both theoretically in computer simulations as well as experimentally in mechanical test lungs. In both the simulations and experimental measurements, naïve shared ventilation resulted in large imbalances across individual tidal volume delivery, dependent on imbalances across patient mechanical properties. The proposed breathing circuit modifications for shared VCV and shared PCV enabled optimization of tidal volume distributions. Individual tidal volume for one patient during shared VCV was sensitive to changes in the mechanical properties of other patients. By contrast, shared PCV enabled independent control of individual patient-received ventilation. Of the shared ventilation strategies considered, shared PCV, with the inclusion of in-line pressure-relief valves in the individual inspiratory and expiratory limbs, offers the greatest degree of safety and lowest risk of catastrophic mechanical interactions between multiple patients connected to a single ventilator.

Parameter updating of a patient-specific lung mechanics model for optimising mechanical ventilation

Mechanical ventilation (MV) is the primary way to treat patients with acute respiratory distress syndrome (ARDS) in the intensive care unit (ICU). Positive-end-expiratory-pressure (PEEP) is often applied in MV to maximise gas exchange and prevent further lung damage. However, optimal MV with patient-specific PEEP level is subjective, based on clinician experience, thus increasing the risk variability, and cost of care. In this study, a single compartment lung mechanics model is employed to predict pressure outcomes at higher PEEP levels using data from lower PEEP levels. Particularly, a hysteresis loop analysis (HLA) algorithm is applied to both the dynostatic curve and pressure-volume (PV) loop to identify the lung elastance at lower PEEP levels. Pulmonary resistance can then be calculated with measured airway pressure and identified elastance. Finally, the elastance and resistance at higher PEEP levels are predicted based on model fitting techniques to obtain the pressure with changes of PEEP. The result of pressure fitting and prediction show 95% of the airway pressure curve errors are within 3% across all the 8 data sets, while peak-inspiratory-pressure (PIP) prediction errors are within 1% for all data sets. The overall approach is readily automated, thus providing an initial critical information in determining optimal MV and PEEP settings. Such a model could also be used to validate the prediction accuracy of other more complex models and improve the confidence of their clinical application. Most importantly, the ability to predict PIP and overall pressure trajectories provide a means to safely titrate PEEP to optimal levels without the necessary to build an accurate enough mathematical model which could cost plenty of time and effort.

Daily Practice of Mechanical Ventilation and Weaning in Turkish PICUs: A Multicenter Prospective Survey.

To investigate conventional mechanical ventilation weaning characteristics of patients requiring conventional mechanical ventilation support for greater than 48 hours within the PICU. The prospective observational multicenter cohort study was conducted at 15 hospitals. Data were being collected from November 2013 to June 2014, with two designated researchers from each center responsible for follow-up and data entry. Fifteen tertiary PICUs in Turkey. Patients between 1 month and 18 years old requiring conventional mechanical ventilation for greater than 48 hours were included. A single-center was not permitted to surpass 20% of the total sample size. Patients with no plans for conventional mechanical ventilation weaning were excluded. Conventional mechanical ventilation MEASUREMENTS AND MAIN RESULTS:: Pertinent variables included PICU and patient demographics, including clinical data, chronic diseases, comorbid conditions, and reasons for intubation. Conventional mechanical ventilation mode and weaning data were characterized by daily ventilator parameters and blood gases. Patients were monitored until hospital discharge. Of the 410 recruited patients, 320 were included for analyses. A diagnosis of sepsis requiring intubation and high initial peak inspiratory pressures correlated with a longer weaning period (mean, 3.65 vs 1.05-2.17 d; p < 0.001). Conversely, age, admission Pediatric Risk of Mortality III scores, days of conventional mechanical ventilation before weaning, ventilator mode, and chronic disease were not related to weaning duration. Pediatric patients requiring conventional mechanical ventilation with a diagnosis of sepsis and high initial peak inspiratory pressures may require longer conventional mechanical ventilation weaning prior to extubation. Causative factors and optimal weaning for this cohort needs further consideration.

Effects of Peak Inspiratory Pressure-Guided Setting of Intracuff Pressure for Laryngeal Mask Airway Supreme™ Use during Laparoscopic Cholecystectomy: A Randomized Controlled Trial

Purpose To determine the effects of peak inspiratory pressure (PIP)-guided intracuff pressure (ICP) modulation of laryngeal mask airway (LMA) Supreme™ during laparoscopic cholecystectomy. Methods Totally 120 patients were randomly divided using computer-generated numbers into a control group (n = 60; ICP, 60 cmH2O) and a PIP group (n = 60), in which ICP was increased with 5 cmH2O each time from PIP level until no air leaks from the oropharynx. PIP, ICP, cuff volume (CV), oropharyngeal leak pressure (OLP) and leak fraction (LF) were recorded before and after pneumoperitoneum establishment. Postoperative pharyngolaryngeal complications (sore throat, dysphagia, pharyngeal hematoma, and dysphonia) were also recorded. Results Demographic data were similar in the two groups. The CV and ICP before and after pneumoperitoneum were significantly lower in the PIP group (CV: 15.6 ± 2.3 mL and 21.0 ± 2.6 mL; ICP: 14.3 ± 2.9 cmH2O and 20.5 ± 3.4 cmH2O) than in the control group (CV: 33.0 ± 2.8 mL and 32.8 ± 1.9 mL; ICP: 60.0 ± 0.1 cmH2O and 60.0 ± 0.1 cmH2O) (P < 0.05). Although OLP was lower in the PIP group (P < 0.05), the LF was similar in the two groups (P > 0.05). There were fewer postoperative pharyngolaryngeal complications in the PIP group (P < 0.05). Conclusions Compared with a fixed ICP of 60 cmH2O, PIP-guided ICP modulation during LMA Supreme™ use provided effective airway sealing at a lower CV and ICP, and produced fewer postoperative pharyngolaryngeal complications in patients undergoing laparoscopic cholecystectomy.

Clinical performance of Ambu AuraGainTM versus i-gelTM in anesthetized children: a prospective, randomized controlled trial.

BackgroundAmbu AuraGain and i-gel have different characteristics in design each other. However, few reports evaluate which device has more benefits for ventilation in children undergoing paralyzed general anesthesia. This prospective, randomized controlled trial compared the clinical performance AuraGain and i-gel in anesthetized children.MethodsChildren aged between 1 month and 7 years undergoing elective surgery were randomly assigned to the AuraGain and i-gel groups. The primary outcome was initial oropharyngeal leak pressure (OLP). Secondary outcomes were OLP at 10 min post-insertion, first-attempt and total insertion success rates, number of attempts and ease of gastric suction catheter placement, peak inspiratory pressure, fiberoptic bronchoscopic view score, ventilation quality, requirement of additional manipulation post-insertion, and complications.ResultsData of 93 patients were analyzed. The initial OLPs of the AuraGain and i-gel were 27.5 ± 7.7 and 25.0 ± 8.0 cmH2O, respectively (P = 0.130). The OLP was significantly increased 10 min post-insertion in both groups. The initial success rates of the AuraGain and i-gel insertion were comparable. Suction catheter placement via the gastric port was easier (P = 0.018) and fiberoptic bronchoscopic view was better with the AuraGain (P < 0.001). The i-gel required additional manipulations post-insertion (P = 0.038). The incidence of complications during the emergence period was 10.8% for the i-gelTM and 2.2% for the AuraGain (P = 0.1)ConclusionsOLP is comparable between AuraGain and i-gel. The AuraGain would be more favorable than the i-gelTM for use in pediatric patients under general anesthesia considering other outcomes.

Predicting use of high-flow nasal cannula therapy following extubation in paediatrics.

High-flow nasal cannula (HFNC) therapy is widely used for respiratory support within paediatrics, most commonly used as a supportive measure in acute respiratory failure, aiming to avoid invasive mechanical ventilation (IMV). It is increasingly being used following extubation of critically ill children potentially at a higher risk of requiring re-intubation. Less data indicate the use for post-extubation HFNC therapy or possible clinical outcomes of this therapy. To identify reasons for, and variables to predict, the use of HFNC therapy post-extubation. This was a retrospective case-control study. All children admitted to a nine-bedded regional paediatric intensive care unit requiring IMV between 18 December 2017 and 28 November 2018 were identified. The demographic data and bedside clinical and laboratory variables of the patients requiring HFNC therapy were compared with those who did not require HFNC. There was no statistical difference in the median age and weight of children receiving HFNC therapy post-extubation compared with children not receiving it. In a logistic regression model, the highest ventilation (peak inspiratory pressure) and oxygen requirements in the first 24 hours of admission, along with the presence of comorbidity and use of HFNC therapy prior to intubation, predicted the use of HFNC following extubation, (r2 0.42, area under the receiver operating curve 0.843, P < .0001). The direct correlation between high initial ventilatory requirements and pre-existing comorbidity was significant for the use of post-extubation HFNC therapy. This may be useful to stratify children in the use of HFNC therapy post-extubation in the critically ill population. This study provides evidence that it may be possible to predict the use of HFNC therapy post-extubation. Avoiding unnecessary use of this therapy improves patient care while providing a positive economic impact.

Ventilator-associated Events in Children: Controversies and Research Needs.

Ventilator-associated Events in Children: Controversies and Research Needs.

Predictors of Bronchopulmonary Dysplasia in Saudi Preterm Infants

Background: Bronchopulmonary dysplasia (BPD) is a major cause of morbidity and mortality among preterm infants. Objective: To determine BPD prevalence and to identify factors that predict the development of BPD. Patients and Methods: We performed a retrospective cohort study of all neonates admitted to the neonatal intensive care unit (NICU) between 2009 and 2019 with gestational age (GA) less than 32 weeks and birth weight (BW) less than 1500 g. Results: A total of 637 preterm infants included in the study, of whom 194 (30.5%) infants developed BPD. Of the 194 preterm infants who developed BPD 89 (45.9 %) had mild, 59 (30.4%) had moderate and 46 (23.7%) had severe BPD. Multivariate analysis revealed that low GA (odds ratio [OR]: 0.62; 95% confidence interval [CI]: 0.43-0.98), low BW (OR: 20.6; 95% CI: 17.1-29.3), use of mechanical ventilation (OR: 1.07; 95% CI: 0.87-1.54), higher peak inspiratory pressure (PIP) (OR: 1.48; 95% CI: 1.44-1.91), higher fraction of inspired oxygen (FiO2) use (OR: 0.11; 95% CI: 0.05-0.19), duration of mechanical ventilation (OR: 3.56; 95% CI: 4.28-3.75) and frequent blood transfusion (OR: 0.65; 95% CI: 0.53-0.87) were identified as the principal risk factors for BPD. Conclusions: The prevalence of BPD among Saudi preterm infants was 30.5%. The most relevant predictors of BPD were GA, BW, mechanical ventilation, higher PIP, higher FiO2 use, duration of mechanical ventilation and frequent blood transfusion.

Airway Pressure Release Ventilation as a Rescue Therapy in Pediatric Acute Respiratory Distress Syndrome.

ObjectivesTo describe experience with airway pressure release ventilation (APRV) in children with severe acute respiratory distress syndrome (ARDS) refractory to conventional low tidal volume ventilation.MethodsThis retrospective observational study was performed in an 11-bed, level 3 pediatric intensive care unit. Evaluation was made of 30 pediatric patients receiving airway pressure release ventilation as rescue therapy for severe ARDS.ResultsPatients were switched to APRV on an average 3.2 ± 2.6 d following intubation. When changed from conventional mechanical ventilation (CMV) to APRV, there was an expected increase in the SpO2/FiO2 ratio (165.1 ± 13.6 vs. 131.7 ± 10.2; p = 0.035). Mean peak inspiratory pressure was significantly lower during APRV (25.4 ± 1.26 vs. 29.8 ± 0.60, p < 0.001) compared to CMV prior to APRV but mean airway pressure (Paw) was significantly higher during APRV (19.1 ± 0.9 vs. 15.3 ± 1.3, p < 0.001). Hospital mortality in this study group was 16.6%.ConclusionsThe results of this study support the hypothesis that APRV may offer potential clinical advantages for ventilatory management and may be considered as an alternative rescue mechanical ventilation mode in pediatric ARDS patients refractory to conventional ventilation.

Club Cell Protein, CC10, Attenuates Acute Respiratory Distress Syndrome Induced by Smoke Inhalation.

To evaluate the dose effects of Recombinant human Club cell 10-kDa protein (rhCC10) on lung function in a well-characterized ovine model of acute respiratory distress syndrome (ARDS) induced by smoke inhalation injury (SII); specifically, the potential of rhCC10 protein to control the inflammatory response and protect pulmonary tissue and function following SII. Randomized, controlled, prospective, and large animal translational studies. University large animal intensive care unit. Thirty-six adult female sheep were surgically prepared and allocated into five groups (Sham (no SII), n = 6; 1 mg/kg/d CC10, n = 8; 3 mg/kg/d CC10, n = 7; 10 mg/kg/d CC10, n = 8; Control SII, n = 7). All groups except the sham group were subjected to SII with cooled cotton smoke. Then, the animals were placed on a ventilator, treated with 1, 3, and 10 mg/kg/d of intravenous rhCC10 or vehicle, divided evenly into two administrations per day every 12 h, fluid resuscitated, and monitored for 48 h in a conscious state. The group treated with 10 mg/kg/d rhCC10 attenuated changes in the following variables: PaO2/FiO2 ratio, oxygenation index, and peak inspiratory pressure; neutrophil content in the airway and myeloperoxidase levels; obstruction of the large and small airways; systemic leakage of fluid and proteins, and pulmonary edema. In this study, high-dose rhCC10 significantly attenuated ARDS progression and lung dysfunction and significantly reduced systemic extravasation of fluid and proteins, normalizing fluid balance. Based on these results, rhCC10 may be considered a novel therapeutic option for the treatment of SII-induced ARDS.

Deep neuromuscular blockade during spinal surgery reduces intra-operative blood loss: A randomised clinical trial.

Spinal surgery is usually performed in the prone position using a posterior approach. However, the prone position may cause venous engorgement in the back and thus increase surgical bleeding with interruption of surgery. The prone position also affects cardiac output since large vessels are compressed decreasing venous return to the heart. We hypothesised that deep neuromuscular blockade would be associated with less surgical bleeding during spinal surgery in the prone position. Randomised, single blinded trial. University teaching hospital. Eighty-eight patients in two groups. Patients were randomly assigned to moderate neuromuscular blockade or deep neuromuscular blockade. In the moderate neuromuscular blockade group, administration of rocuronium was adjusted such that the train-of-four count was one to two. In the deep neuromuscular blockade group, rocuronium administration was adjusted such that the train-of-four count was zero with a posttetanic count 2 or less. The primary outcome was the volume of intra-operative surgical bleeding. The surgeon's satisfaction with operating conditions, haemodynamic and respiratory status, and postoperative pain scores were evaluated. The median [IQR] volume of intra-operative surgical bleeding was significantly less in the deep neuromuscular blockade group than in the moderate neuromuscular blockade group; 300 ml [200 to 494] vs. 415 ml [240 to 601]; difference: 117 ml (95% CI, 9 to 244; P = 0.044). The mean ± SD surgeon's satisfaction with the intra-operative surgical conditions was greater in the deep neuromuscular blockade group than in the moderate neuromuscular blockade group; 3.5 ± 1.0 vs. 2.9 ± 0.9 (P = 0.004). In intergroup comparisons of respiratory variables, peak inspiratory pressure was lower in the deep neuromuscular blockade group overall (P < 0.001). The median [IQR] postoperative pain score was lower in the deep neuromuscular blockade group than the moderate neuromuscular blockade group; 50 [36 to 60] vs. 60 [50 to 70], (P = 0.023). Deep neuromuscular blockade reduced intra-operative surgical bleeding in patients undergoing spinal surgery. This may be related to greater relaxation in the back muscles and lower intra-operative peak inspiratory pressure when compared with moderate neuromuscular blockade. KCT0001264 (http://cris.nih.go.kr).

Effect of Pressure-Controlled Ventilation-Volume Guaranteed on One-Lung Ventilation in Elderly Patients Undergoing Thoracotomy

BackgroundVolume-controlled ventilation (VCV) in one-lung ventilation (OLV) is most commonly used in thoracotomy, but pressure-controlled ventilation-volume guaranteed (PCV-VG) is used in elderly patients to improve arterial oxygenation, reduce inflammatory factors, and decrease acute lung injury (ALI). The purpose of this study was to investigate the effects of these 2 different ventilation modes – VCV versus PCV-VG – during OLV in elderly patients undergoing thoracoscopic lobectomy.Material/MethodsSixty patients undergoing thoracoscopic lobectomy from September 2018 to February 2019 at Cangzhou Central Hospital, Hebei, China were randomly assigned to a VCV group or a PCV-VG group. Pulmonary dynamic compliance (Cdyn), peak inspiratory pressure (PIP), arterial blood gas, and inflammatory factors were monitored to assess lung function. The Clinical Trial Registration Identifier number is ChiCTR1800017835.ResultsCompared with the VCV group, PIP in the PCV-VG group was significantly lower (P=0.01) and Cdyn was significantly higher at 30 min after one-lung ventilation (P=0.01). MAP of the PCV-VG group was higher than in the VCV group (P=0.01). MAP of the PCV-VG group was also higher than in the VCV group at 30 min after one-lung ventilation (P=0.01). The concentration of neutrophil elastase (NE) in the PCV-VG group was significantly lower than in the VCV group (P=0.01).ConclusionsCompared with VCV, PCV-VG mode reduced airway pressure in patients undergoing thoracotomy and also decreased the release of NE and reduced inflammatory response and lung injury. We conclude that PCV-VG mode can protect the lung function of elderly patients undergoing thoracotomy.

Pulmonary stretch receptor activity during partial liquid ventilation with different pressure waveforms

BackgroundThe aim of the present study was to investigate pulmonary stretch receptor activity (PSR) under different peak inspiratory pressures (PIPs) and inspiratory pressure waveforms during partial liquid (PLV) and gas ventilation (GV). MethodsPSR instantaneous impulse frequency (PSRfimp) was recorded from single fibers in the vagal nerve during PLV and GV in young cats. PIPs were set at 1.2/1.8/2.2/2.7 kPa, and square and sinusoidal pressure waveforms were applied. ResultsPSRfimp at the start of inspiration increased with increasing PIPs, and was steeper and higher with square than with sinusoidal waveforms (p < 0.05). Total number of impulses, peak and mean PSRfimp were lower during PLV than GV at the lowest and highest PIPs (p < 0.025). Time to peak PSRfimp was shorter with square than with sinusoidal waveforms at all pressures and ventilations (p < 0.005). Irrespective of waveform, lower PIPs yielded lower ventilation during PLV. ConclusionAs assessed by PSRfimp, increased PIPs do not expose the lungs to more stretching during PLV than during GV, with only minor differences between square and sinusoidal waveforms.

The use of pressure-controlled mechanical ventilation in a swine model of intraoperative pediatric cardiac arrest.

Current pediatric resuscitation guidelines suggest that resuscitators using an advanced airway deliver 8-10 breaths per minute while carefully avoiding excessive ventilation. In the intraoperative setting, having a dedicated ventilation rescuer may be difficult because of limited personnel. Continuing pressure-controlled mechanical ventilation during resuscitation for intraoperative cardiac arrest reduces personnel needed and the risk of hyperventilation but might risk hypoventilation during chest compression delivery. To determine whether the use of pressure-controlled mechanical ventilation at prearrest settings provides normoxia and normocarbia during resuscitation from cardiac arrest. We retrospectively analyzed combined data from preclinical randomized controlled trials. Two-week-old swine (3-4kg) underwent asphyxia-induced cardiac arrest. Animals were resuscitated with periods of basic and advanced life support. During resuscitation, pressure-controlled mechanical ventilation was delivered at the prearrest respiratory rate, peak inspiratory pressure, and positive end-expiratory pressure. Arterial blood gases were measured prearrest, at 11minutes of asphyxia, and at 8 and 20minutes of cardiopulmonary resuscitation. Piglets (n=154) received pressure-controlled mechanical ventilation before and during cardiopulmonary resuscitation with a peak inspiratory pressure of 14-15cm H2 O, positive end-expiratory pressure of 4cm H2 O, 20 breaths/minute, and an inspiratory:expiratory ratio of 1:2. During asphyxia, the arterial blood gas showed the expected severe hypercarbia and hypoxia. Continuing pressure-controlled mechanical ventilation using prearrest parameters and increasing the FiO2 to 1.0 returned the PaCO2 to prearrest levels and slightly increased the partial pressure of arterial oxygen at 8 and 20minutes of cardiopulmonary resuscitation. In this piglet model of resuscitation from asphyxial arrest, pressure-controlled mechanical ventilation during cardiopulmonary resuscitation at the prearrest ventilator settings with an FiO2 of 1.0 provides adequate oxygenation and restores normocarbia. Clinical investigation is warranted to determine the benefits of continuing pressure-controlled mechanical ventilation at prearrest parameters during pediatric cardiopulmonary resuscitation.