Higher Mean Airway Pressure Research Articles

Factors that mediate change in creatinine and acute kidney injury after the Norwood operation: insights from high-fidelity haemodynamic monitoring data.

Acute kidney injury is a common postoperative complication of paediatric cardiac surgery associated with increased morbidity and mortality. The purpose of this study is to characterise associations between haemodynamic parameters, clinical parameters, and medical interventions, on acute kidney injury. Nine patients with univentricular physiology undergoing the Norwood procedure from a single-centre tertiary care paediatric cardiac ICU were included (September 2022 to March 2023). Patients were monitored with the T3 software. Data were analysed using a Fisher exact test, Mann-Whitney-U test, LASSO-based machine learning techniques, and receiver operator curve analyses. Over 27,000 datapoints were included. Acute kidney injury occurred in 2 patients (22%) during this period. Net fluid balance and renal oxygen extraction were independently associated with acute kidney injury, while commonly used metrics of pressure (systolic, diastolic, or mean arterial blood pressure) were not. The resulting acute kidney injury risk score was (4.1 × fluid balance) + (1.9 × renal oxygen extraction). The risk score was significantly higher in acute kidney injury with a score of 32.9 compared to 7.9 (p < 0.01). Optimal cut-offs for fluid balance (7 mL/hr) and renal oxygen extraction (29%) were identified. Higher serum creatinine:baseline creatinine ratio was associated with a higher mean airway pressure, higher renal oxygen extraction, higher mean arterial blood pressure, higher vasoactive inotropic score, and fluid balance. Among patients with univentricular physiology undergoing the Norwood procedure, renal oxygen extraction and a higher net fluid balance are independently associated with increased risk of acute kidney injury. Renal perfusion pressure is not significantly associated with acute kidney injury.

Apneustic anesthesia ventilation improves pulmonary function in anesthetized bottlenose dolphins (Tursiops truncatus).

Use of mechanical ventilation during general anesthesia is a necessary practice in the anesthetization of small cetaceans as spontaneous ventilation fails to provide adequate gas exchange. Currently available methods of ventilation do not account for the intermittent breathing strategy of representative species within this infraorder of fully aquatic mammals and may have a significant effect on cardiac and respiratory physiology. To understand the impact of mechanical ventilation on cardiopulmonary function in one small species of cetacean, the bottlenose dolphin (Tursiops truncatus), we compared controlled mechanical ventilation (CMV) to a novel ventilation method known as apneustic anesthesia ventilation (AAV). AAV simulates the normal inspiratory breath-hold pattern of dolphins. Ten anesthetic procedures (dental procedure, n = 9; bronchoscopy, n = 2) were performed on nine dolphins (age range: 10-42 years; mean = 32 years; median = 37 years; female = 3, 40%; male = 6, 60%). In a cross-over study design, dolphins were instrumented and randomly assigned to AAV or CMV as the initial mode of ventilation, then switched to the alternate mode. Baseline cardiopulmonary data were collected and again after 30 min on each mode of ventilation. Cardiac index, stroke volume index, systemic vascular resistance, alveolar dead space, alveolar-arterial oxygen tension gradient, arterial oxygen content, oxygen delivery index, and dynamic respiratory system compliance index were calculated at each of the four time points. During AAV, dolphins had higher arterial oxygen tension, higher mean airway pressure, reduced alveolar dead space ventilation and lower alveolar-arterial oxygen difference. Cardiovascular performance was not statistically different between the two modes. Our study suggests AAV, which more closely resembles the conscious intermittent respiratory pattern phenotype of dolphins, improves ventilation and pulmonary function in the anesthetized dolphin. Future studies should evaluate the cardiopulmonary effects of neutral buoyancy and cardiopulmonary sparing drug protocols to reduce the need for hemodynamic support of current protocols.

Ultrasound Differentiation of Twins with Discordant Congenital Diaphragmatic Hernia in the Delivery Room

AbstractMost infants with prenatally diagnosed congenital diaphragmatic hernia (CDH) are intubated rapidly after birth to optimize oxygenation and ventilation while avoiding abdominal distention and high mean airway pressures. A twin pregnancy complicated by one twin with a CDH diagnosis is a rare event and is associated with preterm delivery and low birth weight compared to singletons with CDH. In rare cases of discordant CDH in twin pregnancies with an absence of external distinguishing features (similar weights, fetal presentation, and sex), it may be difficult to quickly determine which twin has CDH in the delivery room (DR), raising ambiguity about the best management of both infants. This case describes the successful use of ultrasound (US) in the DR to rapidly diagnose the presence or absence of CDH in discordant twins. By developing a resuscitation algorithm and using in situ simulations prior to delivery, the twin with CDH was rapidly identified, intubated, and transported to the neonatal intensive care unit (NICU) for further management. The twin without CDH received routine care and was transferred to the well-baby nursery. Interprofessional planning and simulation may be used to design a safe resuscitation plan incorporating US diagnosis of diaphragmatic anomalies into the Neonatal Resuscitation Program (NRP) algorithm.

Diaphragm atrophy during invasive mechanical ventilation is related to extubation failure in preterm infants: An ultrasound study.

Diaphragm dysfunction is associated with poor outcomes in critically ill patients. Ventilator-induced diaphragmatic dysfunction (VIDD), including diaphragm atrophy (DA), is poorly studied in newborns. We aimed to assess VIDD and its associations in newborns. Single-center prospective study. Diaphragm thickness was measured at end-inspiration (TDI) and end-expiration (TDE) on the right midaxillary line. DA was defined as decrease in TDE ≥ 10%. Daily measurements were recorded in preterm newborns on invasive mechanical ventilation (IMV) for ≥2 days. Clinical characteristics of patients and extubation failure were recorded. Univariate analysis, logistic regression, and mixed models were performed to describe VIDD and associated factors. We studied 17 patients (median gestational age 270/7 weeks) and 22 IMV cycles (median duration 9 days). Median TDE decreased from 0.118 cm (interquartile range [IQR]0.094-0.165) on the first IMV day to 0.104 cm (IQR 0.083-0.120) on the last IMV day (p = .092). DA occurred in 11 IMV cycles (50%) from 10 infants early during IMV (median: second IMV day). Mean airway pressure (MAP) and lung ultrasound score (LUS) on the first IMV day were significantly higher in patients who developed DA. DA was more frequent in patients with extubation failure than in those with extubation success within 7 days (83.3 vs. 33.3%, p = .038). DA, significantly associated with extubation failure, occurred in 58.8% of the study infants on IMV. Higher MAP and LUS at IMV start were associated with DA. Our results suggest a potential role of diaphragm ultrasound to assess DA and predict extubation failure in clinical practice.

Impact on cerebral hemodynamics of the use of volume guarantee combined with high frequency oscillatory ventilation in a neonatal animal respiratory distress model.

No differences were observed at cerebral hemodynamic between respiratory assistance in HFOV with and without VG, being the latter ventilatory strategy equally safe. • Preterm have a situation of fragility of cerebral perfusion wich means that any mechanical ventilation strategy can have a significant influence. High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. Several studies have compared CMV and HFOV and their effects at hemodynamic level. It is known that the use of high mean airway pressure in HFOV can cause an increase in pulmonary vascular resistance with a decrease in thoracic venous return. • The possible impact of VAFO + VG on cerebral hemodynamics is unknown. Due the lack of studies and the existing controversy, we have carried out this research project in an experimental animal model with the aim of evaluating the cerebral hemodynamic repercussion of the use of VG in HFOV compared to the classic strategy without VG.

Plasma proteoglycan 4: a novel biomarker for acute lung injury after pediatric cardiac surgery.

Identification of biological molecules related to post cardiopulmonary bypass (CPB) lung injury could help diagnose, predict and potentially impact patient's clinical course after cardiac surgery. Proteoglycan 4 (PRG4) initially identified as potential biomarker for patients with prolonged mechanical ventilation following CPB in a prior study. To further validate these findings, we sought to understand the association of lower plasma PRG4 with prolonged mechanical ventilation and worse lung compliance in a larger cohort of pediatric patients post CPB. Retrospective chart review study. Pediatric Cardiac Intensive Care Unit, Tertiary Hospital. Infants <1 year old with tetralogy of Fallot, ventricular septal defect, or atrioventricular septal defect who underwent surgical repair 2012-2020 and had stored plasma samples in our biorepository were screened for inclusion. Patients with mechanical ventilation before surgery were excluded. Patients were divided into quartiles based on postoperative duration of mechanical ventilation (control <25th percentile, study >75th percentile). Preoperative and 48-hour postoperative samples for each cohort (20 patients each) were tested for PRG4 level using enzyme-linked immunosorbent assay (ELISA) technique. Study group had lower lung compliance, higher mean airway pressure and higher oxygen need postoperative when compared to control group. Plasma PRG4 levels before surgery and 48 hours postoperative were lower in study group compared to control group (P=0.0232 preoperative; P=0.0016 postoperative). Plasma PRG4 levels were compared preoperative to PRG4 levels postoperative in both group, there was no statistically significant difference (study group: P=0.0869; control group: P=0.6500). Lower levels of plasma PRG4 is associated with longer duration of mechanical ventilation, worse ventilator compliance and higher oxygen requirement after cardiac surgery in our patient population. Further validation of this finding in a larger and more diverse patient population is necessary prior to its application at the bedside.

Ultrasound-assessed lung aeration, oxygenation and respiratory care in neonatal bile acid pneumonia: a nested case-control study.

Neonatal bile acid pneumonia (NBAP) occurs in neonates following obstetric cholestasis. We aimed to study the lung aeration and respiratory support of NBAP. Nested, case/control study enrolling age-matched neonates with NBAP, respiratory distress syndrome (RDS) or transient tachypnoea (TTN). Lung aeration and oxygenation were assessed with lung ultrasound score, oxygenation index and SpO2 /FiO2 . Nineteen, 22 and 25 neonates with NBAP, RDS and TTN, respectively were studied (mean gestational age 33 (2.2) weeks, 30 (45.5%) males). Upon admission, RDS patients had worst lung ultrasound score (p=0.022) and oxygenation index (p=0.001), while NBAP and TTN neonates had similar values. At the worst time-point, NBAP and RDS patients showed similar oxygenation index (NBAP: 4.6 (2), RDS: 5.7 (3)) and SpO2 /FiO2 (NBAP: 3.1 (1.1), RDS: 2.7 (1)) which were worse than those of TTN patients (oxygenation index: p=0.015, SpO2 /FiO2 : p=0.001). RDS neonates needed the longest continuous positive airway pressure and highest mean airway pressure, but NBAP neonates needed invasive ventilation (26.3%, p=0.01) and surfactant (31.6%, p=0.003) more often than TTN patients who never needed these. NBAP was a mild disorder in the first hours of life but subsequently worsened and became similar to RDS.

Mechanical ventilation with ten versus twenty breaths per minute during cardio-pulmonary resuscitation for out-of-hospital cardiac arrest: A randomised controlled trial

Aim of the studyThis study sought to assess the effects of increasing the ventilatory rate from 10 min−1 to 20 min−1 using a mechanical ventilator during cardio-pulmonary resuscitation (CPR) for out-of-hospital cardiac arrest (OHCA) on ventilation, acid-base-status, and outcomes. MethodsThis was a randomised, controlled, single-centre trial in adult patients receiving CPR including advanced airway management and mechanical ventilation offered by staff of a prehospital physician response unit (PRU). Ventilation was conducted using a turbine-driven ventilator (volume-controlled ventilation, tidal volume 6 ml per kg of ideal body weight, positive end-expiratory pressure (PEEP) 0 mmHg, inspiratory oxygen fraction (FiO2) 100%), frequency was pre-set at either 10 or 20 breaths per minute according to week of randomisation. If possible, an arterial line was placed and blood gas analysis was performed. ResultsThe study was terminated early due to slow recruitment. 46 patients (23 per group) were included. Patients in the 20 min−1 group received higher expiratory minute volumes [8.8 (6.8–9.9) vs. 4.9 (4.2–5.7) litres, p < 0.001] without higher mean airway pressures [11.6 (9.8–13.6) vs. 9.8 (8.5–12.0) mmHg, p = 0.496] or peak airway pressures [42.5 (36.5–45.9) vs. 41.4 (32.2–51.7) mmHg, p = 0.895]. Rates of ROSC [12 of 23 (52%) vs. 11 of 23 (48%), p = 0.768], median pH [6.83 (6.65–7.05) vs. 6.89 (6.80–6.97), p = 0.913], and median pCO2 [78 (51–105) vs. 86 (73–107) mmHg, p > 0.999] did not differ between groups. Conclusion20 instead of 10 mechanical ventilations during CPR increase ventilation volumes per minute, but do not improve CO2 washout, acidaemia, oxygenation, or rate of ROSC.ClinicalTrials.gov Identifier: NCT04657393.

598: SINGLE-INSTITUTION EXPERIENCE WITH APRV

Introduction: High mean airway pressure (MAP) ventilation is used in pediatric ARDS to increase oxygenation. Nonconventional approaches include high-frequency oscillatory ventilation (HFOV) and airway pressure release ventilation (APRV). Pediatric HFOV has been relatively well described in literature; APRV has been only sporadically reported in the pediatric population. Our center has moved to APRV use before considering HFOV despite a paucity of data. The consequences of this shift are not well understood. This study describes our single-center experience with APRV and compare outcomes to published data. Methods: This is an early interim analysis of a convenience sample of 22 patients from a retrospective cohort study of 197 patients for whom APRV was used between January 2013 and December 2021. Demographics, pre-hospitalization characteristics, and admission variables were collected. We examined ventilator settings, blood gases, oxygenation index, P/F ratios before transition from conventional ventilation and in 12-hour time intervals after transition to APRV. Primary outcomes were mortality and 28-d ventilator free days (VFD). Results: Of the 22 patients, the mean age was 8.4 months and 54% were male. The most common comorbidity was congenital heart disease (40.9%) followed by chronic lung disease (13.6%). Eight-six percent of the patients were diagnosed with ARDS and 57.9% had bacterial pneumonia as the etiology of ARDS. Prior to switching to APRV, 64% of the patients were in pressure control mode of ventilation on a mean FiO2 of 74%. Half of the patients had neuromuscular blockade and 53% received nitric oxide prior to switch to APRV. The average mean airway pressure was 18 cm H2O in conventional ventilation and increased to 23 cm H2O with APRV. Median pHigh (IQR) was 28 (25-32) and median tHigh of 1.65 (1.5-2.7). There was an increase in recorded oxygen saturation (86% to 90%) at 4 hours. Only 32% of patients remained on APRV at 24 hours. Survival to discharge in this cohort was 36.4%. The 28-d VFD was 3.9, driven largely by high mortality. Conclusions: In patients receiving APRV, there was an increase in MAP and improvement in SaO2 after switching to APRV. There was a very high mortality rate in this small subset which requires further investigation.

Clinical outcome of high frequency ventilation in neonates in neonatal intensive care unit

Background: Pulmonary disease is a major cause of mortality and morbidity in neonates. Some of them may require mechanical ventilation with high mean airway pressures to maintain adequate gas exchange. More unconventional modalities such as inverse ratio ventilation, high frequency ventilation or extracorporeal membrane oxygenation (ECMO) may be needed. Objective: To study the clinical outcome of neonates managed with HFV for past 5 years in Neonatal Intensive Care Unit (NICU). Methods: A retrospective study conducted at NICU from January 2007 to June 2013. All neonates who were managed with HFV were included in the study. Result: There were 39 neonates who were ventilated with HFV during that period. The survival rate was 20.5% (8 out of 39 subjects). 18 developed pulmonary hypertension, 5 of whom survived. Six (15.4%) presented with primary pulmonary hypertension (PHN) and 12 (30.8%) developed secondary PHN. In the survived group, 12.5% developed chronic lung disease and periventricular leukomalacia and in the expired group, 25.8% developed pulmonary haemorrhage. Conclusions: When HFV is instituted in infants who fail to show improvement with conventional ventilation, statistically significant improvement in arterial oxygen tension may occur without any change in oxygenation index. A longer period of conventional ventilation prior to HFV could be one of the factors that could interfere with the successful management with HFV.

Preliminary evaluation of the effects of a 1:1 inspiratory-to-expiratory ratio in anesthetized and ventilated horses

ObjectiveTo describe some cardiorespiratory effects of an inspiratory-to-expiratory (IE) ratio of 1:1 compared with 1:3 in ventilated horses in dorsal recumbency. Study designRandomized crossover experimental study. AnimalsA total of eight anesthetized horses, with 444 (330–485) kg body weight [median (range)]. MethodsHorses were ventilated in dorsal recumbency with a tidal volume of 15 mL kg–1 and a respiratory rate of 8 breaths minute–1, and IE ratios of 1:1 (IE1:1) and 1:3 (IE1:3) in random order, each for 25 minutes after applying a recruitment maneuver. Spirometry, arterial blood gases and dobutamine requirements were recorded in all horses during each treatment. Electrical impedance tomography (EIT) data were recorded in four horses and used to generate functional EIT variables including regional ventilation delay index (RVD), a measure of speed of lung inflation, and end-expiratory lung impedance (EELI), an indicator of functional residual capacity (FRC). Results were assessed with linear and generalized linear mixed models. ResultsCompared with treatment IE1:3, horses ventilated with treatment IE1:1 had higher mean airway pressures and respiratory system compliance (p < 0.014), while peak, end-inspiratory and driving airway pressures were lower (p < 0.001). No differences in arterial oxygenation or dobutamine requirements were observed. PaCO2 was lower in treatment IE1:1 (p = 0.039). Treatment IE1:1 resulted in lower RVD (p < 0.002) and higher EELI (p = 0.023) than treatment IE1:3. Conclusions and clinical relevanceThese results suggest that IE1:1 improved respiratory system mechanics and alveolar ventilation compared with IE1:3, whereas oxygenation and dobutamine requirements were unchanged, although differences were small. In the four horses where EIT was evaluated, IE1:1 led to a faster inflation rate of the lung, possibly the result of increased FRC. The clinical relevance of these findings needs to be further investigated.

Haemodynamic predisposition to acute kidney injury: Shadow and light!

Acute kidney injury (AKI) could well be regarded as a sentinel complication given it is relatively common and associated with a substantial risk of subsequent morbidity and mortality. On the aegis of 'prevention is better than cure', there has been a wide interest in evaluating haemodynamic predisposition to AKI so as to provide a favourable renoprotective haemodynamic milieu to the subset of patients presenting a significant risk of developing AKI. In this context, the last decade has witnessed a series of evaluation of the hypotension value and duration cut-offs associated with risk of AKI across diverse non-operative and operative settings. Nevertheless, a holistic comprehension of the haemodynamic predisposition to AKI has been a laggard with only few reports highlighting the potential of elevated central venous pressure, intra-abdominal hypertension and high mean airway pressures in considerably attenuating the effective renal perfusion, particularly in scenarios where kidneys are highly sensitive to any untoward elevation in the afterload. Despite the inherent autoregulatory mechanisms, the effective renal perfusion pressure (RPP) can be modulated by a number of haemodynamic factors in addition to mean arterial pressure (MAP) as the escalation of renal interstitial pressure, in particular hampers kidney perfusion which in itself is a dynamic interplay of a number of innate pressures. The present article aims to review the subject of haemodynamic predisposition to AKI centralising the focus on effective RPP (over and above the conventional 'tunnel-vision' for MAP) and discuss the relevant literature accumulating in this area of ever-growing clinical interest.

Neonatal pneumothorax in congenital diaphragmatic hernia: Be wary of high ventilatory pressures

BackgroundPatients with congenital diaphragmatic hernia (CDH) require invasive respiratory support and higher ventilator pressures may be associated with barotrauma. We sought to evaluate the risk factors associated with pneumothorax in...

Pulmonary Complications in Premature Infants Using a Beractant or Poractant for Respiratory Distress Syndrome: A Retrospective Cohort Study.

Premature infants are at the risk of developing respiratory distress syndrome (RDS). Beractants and poractants are two commonly used natural surfactants. This retrospective cohort study aims to compare the incidence of pulmonary complications between beractant and poractant treatment groups. This study evaluated 29 patients treated with beractant and 49 patients treated with poractant. The primary outcome was the incidence of air leak syndrome (ALS) and pulmonary hemorrhage. Secondary outcomes included mortality and pulmonary outcomes, such as mechanical ventilation duration, oxygen dependence duration, fraction of inspired oxygen, and mean airway pressure (MAP) requirement. Logistic regression analyses were conducted to identify independent risk factors for significant primary outcomes. No significant difference was found in the demographics between the two groups. A significantly higher incidence of pulmonary hemorrhage was observed in the poractant group (14.3 vs. 0.0%, p = 0.038). The difference in the incidence of ALS between the groups was insignificant (p = 0.536). Logistic regression for the incidence of pulmonary hemorrhage identified coagulopathy as the only significant independent risk factor (odds ratio 39.855, 95% confidence interval [2.912-545.537]; p = 0.006). Secondary outcomes in both treatment groups were similar, except that patients in the poractant group had a higher MAP before surfactant therapy (9 vs. 8 cmH2O, p < 0.001). This study showed a significantly higher incidence of pulmonary hemorrhage in the poractant group. Coagulopathy was identified as an independent risk factor for pulmonary hemorrhage. Future long-term prospective studies are essential to establish the temporal and causal relationships between coagulopathy and pulmonary hemorrhage in premature infants receiving surfactant therapy for RDS; hence, there is the need for a screening protocol before surfactant administration. · A higher incidence of pulmonary hemorrhage was found in the poractant group.. · Coagulopathy was the only significant risk factor that was related to the incidence of pulmonary hemorrhage.. · A screening protocol might be useful to avoid pulmonary hemorrhage in infants receiving surfactant..

Factors associated with successful extubation following the first course of systemic dexamethasone in ventilator-dependent preterm infants with or at risk of developing bronchopulmonary dysplasia.

We aimed to identify factors present at the start of an initial course of systemic dexamethasone that would be associated with successful extubation in mechanically ventilated neonates <30 weeks gestational age (GA) with or at risk of developing bronchopulmonary dysplasia (BPD). We studied a retrospective cohort of neonates (23+0 -29+6 weeks GA), with or at risk of developing BPD, prescribed their first course of systemic dexamethasone to aid in extubation from mechanical ventilation. The data collected only pertained to the first course of dexamethasone. Neonates given dexamethasone for airway edema were not included. The primary outcome of interest was successful extubation (i.e., extubated within 14 days of starting dexamethasone and remaining extubated for at least 7 days). Binary logistic regression was employed. A total of 287 neonates were included. Each additional week of GA at birth led to a 1.53 increase in the odds of successful extubation (95% CI: 1.122-2.096, p < 0.01). Higher average fraction of inspired oxygen (FiO2 ) requirements in the preceding 24 h resulted in a 0.94 decrease in the odds of successful extubation (p < 0.05) and higher mean airway pressure (MAP) resulted in 0.76 decrease in odds of successful extubation (p < 0.01). Mechanically ventilated neonates with or at risk of developing BPD, born at <30 week GA and initiated on dexamethasone to facilitate extubation, had a lower likelihood of successful extubation by Day 14 if they had younger GA at birth, and at the time of commencing steroids had higher MAPs and had higher oxygen requirements.

Extremely low birth weight infant surviving left congenital diaphragmatic hernia: a case report

In this study, we present the case of a 900 g, male infant born at 27+5 weeks, who was placed on high frequency oscillatory ventilation (HFOV) until repair of a left congenital diaphragmatic hernia (CDH) at 39 days of life (DOL). To date, this is the smallest infant with repair of the left CDH reported in the literature. After birth, he passed the cardiopulmonary stabilization phase and successfully underwent delayed surgery; in the process, he received ventilator assistance through HFOV. He weighed 1,660 gm at the time of surgery. We performed the thoracoscopic primary closure of the diaphragmatic defect. He was extubated on post-operation day (POD) 7 and discharged from hospital on POD 36 with 0.1 L/min supplemental oxygen via nasal cannula. He is being followed for growth and development and there has been no recurrence at the surgical site at 24 months of corrected age. In this case, high mean airway pressure (MAP) was required based on the patient’s weight to achieve adequate recruitment of the left lung, and the patient was diagnosed with mental developmental delay on Bayley Scales of Infant Development-II. Thus, we suggest that the postnatal course and long-term outcomes for extremely low birth weight (ELBW) and preterm infants with left CDH is different from that for full-term babies. Therefore, future research should focus on preterm infants with left CDH.

Utilization of Airway Pressure Release Ventilation as a Rescue Strategy in COVID-19 Patients: A Retrospective Analysis.

Background:Airway Pressure Release Ventilation (APRV) is a pressure controlled intermittent mandatory mode of ventilation characterized by prolonged inspiratory time and high mean airway pressure. Several studies have demonstrated that APRV can improve oxygenation and lung recruitment in patients with Acute Respiratory Distress Syndrome (ARDS). Although most patients with COVID-19 meet the Berlin criteria for ARDS, hypoxic respiratory failure due to COVID-19 may differ from traditional ARDS as patients often present with severe, refractory hypoxemia and significant variation in respiratory system compliance. To date, no studies investigating APRV in this patient population have been published. The aim of this study was to evaluate the effectiveness of APRV as a rescue mode of ventilation in critically ill patients diagnosed with COVID-19 and refractory hypoxemia.Methods:We conducted a retrospective analysis of patients admitted with COVID-19 requiring invasive mechanical ventilation who were treated with a trial of APRV for refractory hypoxemia. PaO2/FIO2 (P/F ratio), ventilatory ratio and ventilation outputs before and during APRV were compared.Results:APRV significantly improved the P/F ratio and decreased FIO2 requirements. PaCO2 and ventilatory ratio were also improved. There was an increase in tidal volume per predicted body weight during APRV and a decrease in total minute ventilation. On multivariate analysis, higher inspiratory to expiratory ratio (I: E) and airway pressure were associated with greater improvement in P/F ratio.Conclusions:APRV may improve oxygenation, alveolar ventilation and CO2 clearance in patients with COVID-19 and refractory hypoxemia. These effects are more pronounced with higher airway pressure and inspiratory time.

The effect of preemptive airway pressure release ventilation on patients with high risk for acute respiratory distress syndrome: a randomized controlled trial

Background and objectivesThe objective of this study was to investigate the use of early APRV mode as a lung protective strategy compared to conventional methods with regard to ARDS development. MethodsThe study was designed as a randomized, non-blinded, single-center, superiority trial with two parallel groups and a primary endpoint of ARDS development. Patients under invasive mechanical ventilation who were not diagnosed with ARDS and had Lung Injury Prediction Score greater than 7 were included in the study. The patients were assigned to APRV and P-SIMV + PS mode groups. ResultsPatients were treated with P-SIMV+PS or APRV mode; 33 (50.8%) and 32 (49.2%), respectively. The P/F ratio values were higher in the APRV group on day 3 (p = 0.032). The fraction of inspired oxygen value was lower in the APRV group at day 7 (p = 0.011).While 5 of the 33 patients (15.2%) in the P-SIMV+PS group developed ARDS, one out of the 32 patients (3.1%) in the APRV group developed ARDS during follow-up (p = 0.197). The groups didn’t differ in terms of vasopressor/inotrope requirement, successful extubation rates, and/or mortality rates (p = 1.000, p = 0.911, p = 0.705, respectively). Duration of intensive care unit stay was 8 (2–11) days in the APRV group and 13 (8–81) days in the P-SIMV+PS group (p = 0.019). ConclusionsThe APRV mode can be used safely in selected groups of surgical and medical patients while preserving spontaneous respiration to a make benefit of its lung-protective effects. In comparison to the conventional mode, it is associated with improved oxygenation, higher mean airway pressures, and shorter intensive care unit stay. However, it does not reduce the sedation requirement, ARDS development, or mortality.

Five novel clinical phenotypes for critically ill patients with mechanical ventilation in intensive care units: a retrospective and multi database study

BackgroundAlthough protective mechanical ventilation (MV) has been used in a variety of applications, lung injury may occur in both patients with and without acute respiratory distress syndrome (ARDS). The purpose of this study is to use machine learning to identify clinical phenotypes for critically ill patients with MV in intensive care units (ICUs).MethodsA retrospective cohort study was conducted with 5013 patients who had undergone MV and treatment in the Department of Critical Care Medicine, Peking Union Medical College Hospital. Statistical and machine learning methods were used. All the data used in this study, including demographics, vital signs, circulation parameters and mechanical ventilator parameters, etc., were automatically extracted from the electronic health record (EHR) system. An external database, Medical Information Mart for Intensive Care III (MIMIC III), was used for validation.ResultsPhenotypes were derived from a total of 4009 patients who underwent MV using a latent profile analysis of 22 variables. The associations between the phenotypes and disease severity and clinical outcomes were assessed. Another 1004 patients in the database were enrolled for validation. Of the five derived phenotypes, phenotype I was the most common subgroup (n = 2174; 54.2%) and was mostly composed of the postoperative population. Phenotype II (n = 480; 12.0%) led to the most severe conditions. Phenotype III (n = 241; 6.01%) was associated with high positive end-expiratory pressure (PEEP) and low mean airway pressure. Phenotype IV (n = 368; 9.18%) was associated with high driving pressure, and younger patients comprised a large proportion of the phenotype V group (n = 746; 18.6%). In addition, we found that the mortality rate of Phenotype IV was significantly higher than that of the other phenotypes. In this subgroup, the number of patients in the sequential organ failure assessment (SOFA) score segment (9,22] was 198, the number of deaths was 88, and the mortality rate was higher than 44%. However, the cumulative 28-day mortality of Phenotypes IV and II, which were 101 of 368 (27.4%) and 87 of 480 (18.1%) unique patients, respectively, was significantly higher than those of the other phenotypes. There were consistent phenotype distributions and differences in biomarker patterns by phenotype in the validation cohort, and external verification with MIMIC III further generated supportive results.ConclusionsFive clinical phenotypes were correlated with different disease severities and clinical outcomes, which suggested that these phenotypes may help in understanding heterogeneity in MV treatment effects.

Third-Day Oxygenation Index is an Excellent Predictor of Survival in Children Mechanically Ventilated for Acute Respiratory Distress Syndrome.

PurposeThe aim of this study was to assess the association between oxygenation index (OI) and outcome in children with acute respiratory distress syndrome (ARDS).Patients and MethodsPatients (age, >30 days) in the pediatric intensive care unit from April 2011 to March 2016 with ARDS and who were mechanically ventilated were included. Patients were divided into two age groups: infants (<12month) and older children. Lowest PaO2/FiO2 and SpO2/FiO2 ratios and highest mean airway pressure (MAP) were recorded on the first day of ARDS and after 72 h. OI was calculated on the first and third days of mechanical ventilation (MV) and its association with OI (first and third days) and short-term mortality evaluated at 28 days.ResultsMV was initiated a mean of 2.3 days after admission (median, 1.0 day; maximum 14 days). The average MV duration for all patients was 11.8 (median, 7.0) days. Mean (95% confidence interval (CI)) OI values on the first day of MV were 14.17 (11.94–16.41), 12.72 (10.68–14.75), and 13.24 (11.73–14.74) for infants, older children, and all participants, respectively. In survivors (n=39) mean OI was 11.66 (9.64–13.68) compared with 15.22 (13.03–17.40) in non-survivors (n=31). Logistic regression analysis revealed that OI on day 3 had highly significant prognostic value for mortality (odds ratio, 256.5, 95% CI 27.1–2424, p<0.001), with an AUC of 0.919 (cut-off value, 17; positive predictive value, 0.905; negative predictive value, 0.964; p=0.0001). In contrast, OI on day 1 did not have significant prognostic value (AUC, 0.634; p=0.056) for short-term mortality. Different modes of MV were not significantly associated with outcome (p>0.05).ConclusionOI is a simple, highly accurate, and sensitive predictor of the survival (short-term mortality) of children mechanically ventilated for ARDS.