Low Lung Compliance Research Articles

The effects of robot-assisted laparoscopic surgery with Trendelenburg position on short-term postoperative respiratory diaphragmatic function

ObjectiveTo study how Pneumoperitoneum under Trendelenburg position for robot-assisted laparoscopic surgery impact the perioperative respiratory parameters, diagrammatic function, etc.MethodsPatients undergoing robot-assisted laparoscopic surgery in the Trendelenburg position and patients undergoing general surgery in the supine position were selected. The subjects were divided into two groups according to the type of surgery: robot-assisted surgery group and general surgery group. ① Respiratory parameters such as lung compliance, oxygenation index, and airway pressure were recorded at 5 min after intubation, 1 and 2 h after pneumoperitoneum. ② Diaphragm excursion (DE) and diaphragm thickening fraction (DTF) were recorded before entering the operating room (T1), immediately after extubation (T2), 10 min after extubation (T3), and upon leaving the postanesthesia care unit (T4). ③ Peripheral venous blood (5 ml) was collected before surgery and 30 min after extubation and was analyzed by enzyme-linked immunosorbent assay to determine the serum concentration of Clara cell secretory protein 16 (CC16) and surfactant protein D (SP-D).Result① Compared with the general surgery group (N = 42), the robot-assisted surgery group (N = 46) presented a significantly higher airway pressure and lower lung compliance during the surgery(P < 0.001). ② In the robot-assisted surgery group, the DE significantly decreased after surgery (P < 0.001), which persisted until patients were discharged from the PACU (P < 0.001), whereas the DTF only showed a transient decrease postoperatively (P < 0.001) and returned to its preoperative levels at discharge (P = 0.115). In the general surgery group, the DE showed a transient decrease after surgery(P = 0.011) which recovered to the preoperative levels at discharge (P = 1). No significant difference in the DTF was observed among T1, T2, T3, and T4. ③ Both the general and robot-assisted surgery reduced the postoperative serum levels of SP-D (P < 0.05), while the robot-assisted surgery increased the postoperative levels of CC16 (P < 0.001).ConclusionRobot-assisted laparoscopic surgery significantly impairs postoperative diaphragm function, which does not recover to preoperative levels at PACU discharge. Elevated levels of serum CC16 after surgery suggest potential lung injury. The adverse effects may be attributed to the prolonged Trendelenburg position and pneumoperitoneum during laparoscopic surgery.

Intubation Time, Lung Mechanics and Outcome in COVID-19 Patients Suffering Acute Respiratory Distress Syndrome: A Single-Center Study.

We examined the effect of intubation time and the lung mechanics on clinical outcomes in coronavirus disease 2019 (COVID-19) patients. Based on the patient's hospital admission, intubation time was defined as early (≤ 2 days) or late (> 2 days). Patients were further divided into three groups; early (≤ 3 days), late (4 - 6 days), and very late (> 6 days) intubated. A total of 194 patients were included; 66.5% male, median age 65 years. Fifty-eight patients (29.9%) were intubated early and 136 (70.1%) late. Early intubated patients revealed lower mortality (44.8% vs. 72%, P < 0.001), were younger (60 vs. 67, P = 0.002), had lower sequential organ failure assessment (SOFA) scores (6 vs. 8, P = 0.002) and higher lung compliance on admission days 1, 6 and 12 (42 vs. 36, P = 0.006; 40 vs. 33, P < 0.001; and 37.5 vs. 32, P < 0.001, respectively). Older age (adjusted odds ratio (aOR) = 1.15, P < 0.001), intubation time (aOR = 1.15, P = 0.004), high SOFA scores (aOR = 1.81, P < 0.001), low partial pressure of oxygen (PaO2)/fractional inspired oxygen tension (FiO2) ratio (aOR = 0.96, P = 0.001), and low lung compliance on admission days 1 and 12 (aOR = 1.12, P = 0.012 and aOR = 1.14, P < 0.001, respectively) were associated with higher mortality. Very late and late intubated patients had higher mortality rates than patients intubated early (78.4% vs. 63.4% vs. 44.6%, respectively, P < 0.001). Among COVID-19 intubated patients, age, late intubation, high SOFA scores, low PaO2/FiO2 ratio, and low lung compliance are associated with higher intensive care unit (ICU) mortality.

Abstract 201: 3D-Printed Automated Pressure-Cycled Resuscitator Maintains Respiratory Homeostasis in Swine With Normal to Moderately Low Lung Compliance

Background: During resuscitation, manual ventilation is commonly used. However, the effectiveness of this approach heavily relies on the skills of the individuals performing, often leading to inconsistent tidal volumes and respiratory rates. Such variations in ventilation can disrupt the removal of CO 2 resulting in altered pH. To address this problem, we leveraged advancements in fluidics and 3D printing to develop a miniature, automated, pressure-cycled resuscitator (inVent) that operates without any moving parts or settings. Hypothesis: The inVent will be able to maintain a pH of 7.2 or higher in swine with a dynamic compliance (Cdyn) of 25-50 ml/cmH 2 O. Goals/Aims: To assess the inVent’s performance in an animal model with normal to severe lung injury. Methods: Hybrid Landrace swine were studied under a protocol approved by the Institutional Animal Care and Use Committee. All swine were anesthetized, and underwent oral intubation. Breath by breath measurements were obtained using the NM3 Monitor (Phillips). All 3 inVent (fluidIQ) resuscitators pressure modules were used pre and post lung injury to fully characterize how each of the modules would react in different lung conditions. Lung injury was induced through a repeated bronchoalveolar lavage. ABG analysis was performed using the epoc system (Siemens). pH values 7.2 or less were considered acidotic while those over 7.2 were considered acceptable. Results: 8 swine with an average weight of 36 (5.8) Kg were studied. 7 swine contributed to 39,770 breaths of pulmonary mechanics and 33 ABGs recorded. Mean Cdyn was lower than anticipated at 25.8 (14.7) mL/cmH 2 O and a pH 7.32 (0.16). Figure 1 demonstrates a linear relationship with compliance and pH. Conclusions: The inVent resuscitator was able to maintain a pH of at least 7.2 in moderate compliance ranges, however struggled to maintain pH of 7.2 or higher in the severely injured. Higher lung compliance ranges are needed to explore possible hyperventilation events.

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.

The Effect of Prone Positioning After Lung Transplantation

BackgroundProne positioning has become a standard therapy in acute respiratory distress syndrome to improve oxygenation and decrease mortality. However, little is known about prone positioning in lung transplant recipients. This large, singe-center analysis investigated whether prone positioning improves gas exchange after lung transplantation. MethodsClinical data of 583 patients were analyzed. Prone position was considered in case of impaired gas exchange Pao2/fraction of oxygen in inhaled air (<250), signs of edema after lung transplantation, and/or evidence of reperfusion injury. Patients with hemodynamic instability or active bleeding were not proned. Impact of prone positioning (n = 165) on gas exchange, early outcome and survival were determined and compared with patients in supine positioning (n = 418). ResultsPatients in prone position were younger, more likely to have interstitial lung disease, and had a higher lung allocation score. Patients were proned for a median of 19 hours (interquartile range,15-26) hours). They had significantly lower Pao2/fraction of oxygen in inhaled air (227 ± 96 vs 303 ± 127 mm Hg, P = .004), and lower lung compliance (24.8 ± 9.1 mL/mbar vs 29.8 ± 9.7 mL/mbar, P < .001) immediately after lung transplantation. Both values significantly improved after prone positioning for 24 hours (Pao2/fraction of oxygen ratio: 331 ± 91 mm Hg; lung compliance: 31.7 ± 20.2 mL/mbar). Survival at 90 days was similar between the 2 groups (93% vs 96%, P = .105). ConclusionsProne positioning led to a significant improvement in lung compliance and oxygenation after lung transplantation. Prospective studies are needed to confirm the benefit of prone positioning in lung transplantation.

Premature monochorionic monoamniotic twins have lower lung compliance at birth than matched dichorionic diamniotic twins.

Premature infants are born with immature lungs that demonstrate abnormal pulmonary function with differences in passive respiratory system compliance and resistance, and functional residual capacity. To our knowledge, no studies have evaluated differences in neonatal pulmonary function based on the type of twin gestation, or chorionicity. Given the effect of chorionicity on outcomes, we aimed to study the effect of twin type, monochorionic monoamniotic (MCMA) vs dichorionic diamniotic (DCDA), on neonatal early pulmonary function tests. In this prospective cohort study, 5 sets of DCDA twins were matched to 5 sets of MCMA twins on gestational age at delivery, latency from antenatal corticosteroid exposure, birthweight, race and gender. Mean values were compared for passive respiratory system compliance and resistance, functional residual capacity, and tidal volume. MCMA infants had a significantly lower compliance (0.64 vs 1.25 mL/cm H2O /kg; p = 0.0001) and significantly higher resistance (0.130 vs 0.087 cm H2O /mL/sec; p = 0.0003) than DCDA infants. Functional residual capacity was lower for MCMA than DCDA infants (17.5 vs 23.4 mL/kg; p = 0.17). Further, 80% of MCMA infants required intubation for surfactant administration compared to 20% of DCDA infants, indicating the clinical significance of these objective measures. Due to the matched case-control design, causality cannot be established. However, we speculate that these differences in lung function may derive from differential exposure to preterm labor and endogenous maternal corticosteroid exposure. Further study is necessary to establish the true causal relationship.

End-expiratory Occlusion Test and Mini-fluid Challenge Test for Predicting Fluid Responsiveness in Acute Circulatory Failure.

Predicting which patients with acute circulatory failure will respond to the fluid by an increase in cardiac output is a daily challenge. End-expiratory occlusion test (EEOT) and mini-fluid challenge (MFC) can be used for assessing fluid responsiveness in patients with spontaneous breathing activity, cardiac arrhythmias, low-tidal volume and/or low lung compliance. The objective of the study is to evaluate the value of EEOT and MFC-induced rise in left ventricular outflow tract (LVOT) velocity time integral (VTI) in predicting fluid responsiveness in acute circulatory failure in comparison to the passive leg-raising (PLR) test. Hundred critically ill ventilated and sedated patients with acute circulatory failure were studied. LVOT VTI was measured by transthoracic echocardiography before and after EEOT (interrupting the ventilator at end-expiration over 15 s), and before and after MFC (100 ml of Ringer lactate was infused over 1 min). The variation of LVOT VTI after EEOT and the MFC was calculated from the baseline. Sensitivity, specificity, and area under the receiver-operating characteristic (AUROC) curve of LVOT VTI after EEOT and MFC to predict fluid responsiveness were determined. After PLR, stroke volume (SV) increased by ≥12% in 49 patients, who were defined as responders and 34 patients in whom the increase in SV <12% were defined as nonresponders. A cutoff of 9.1% Change in VTI after MFC (ΔVTIMFC) predicted fluid responsiveness with an AUROC of 0.96 (P < 0.001) with sensitivity and specificity of 91.5% and 88.9%, respectively. Change in VTI after EEOT (ΔVTIEEOT) >4.3% predicted fluid responsiveness with sensitivity and specificity 89.4% and 88.9%, respectively, with an AUROC of 0.97 (P < 0.001), but in 17 patients, EEOT was not possible because triggering of the ventilator by the patient's inspiratory effort. In conclusion, in mechanically ventilated patients with acute circulatory failure Δ VTIMFC and Δ VTI EEOT accurately predicts fluid responsiveness.

Trajectories of hypoxemia and pulmonary mechanics of COVID-19 ARDS in the NorthCARDS dataset

BackgroundUnderstanding heterogeneity seen in patients with COVIDARDS and comparing to non-COVIDARDS may inform tailored treatments.MethodsA multidisciplinary team of frontline clinicians and data scientists worked to create the Northwell COVIDARDS dataset (NorthCARDS) leveraging over 11,542 COVID-19 hospital admissions. The data was then summarized to examine descriptive differences based on clinically meaningful categories of lung compliance, and to examine trends in oxygenation.FindingsOf the 1536 COVIDARDS patients in the NorthCARDS dataset, there were 531 (34.6%) who had very low lung compliance (< 20 ml/cmH2O), 970 (63.2%) with low-normal compliance (20–50 ml/cmH2O), and 35 (2.2%) with high lung compliance (> 50 ml/cmH2O). The very low compliance group had double the median time to intubation compared to the low-normal group (107.3 h (IQR 25.8, 239.2) vs. 39.5 h (IQR 5.4, 91.6)). Overall, 68.8% (n = 1057) of the patients died during hospitalization. In comparison to non-COVIDARDS reports, there were less patients in the high compliance category (2.2% vs. 12%, compliance ≥ 50 mL/cmH20), and more patients with P/F ≤ 150 (59.8% vs. 45.6%). There is a statistically significant correlation between compliance and P/F ratio. The Oxygenation Index is the highest in the very low compliance group (12.51, SD(6.15)), and lowest in high compliance group (8.78, SD(4.93)).ConclusionsThe respiratory system compliance distribution of COVIDARDS is similar to non-COVIDARDS. In some patients, there may be a relation between time to intubation and duration of high levels of supplemental oxygen treatment on trajectory of lung compliance.

IN-HOSPITAL MORTALITY IN MECHANICALLY VENTILATED PATIENTS WITH COVID-19 WITH DIFFERENT ARDS PHENOTYPES

TOPIC: Chest Infections TYPE: Original Investigations PURPOSE: The purpose of the study is to investigate the in-hospital mortality of mechanically ventilated, COVID-19 (i.e., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) patients with high lung compliance (i.e., atypical acute respiratory distress syndrome (ARDS)) compared to those with low lung compliance (i.e., classic ARDS). METHODS: It is a retrospective cohort study of patients older than 18 years diagnosed with COVID-19 infection that required mechanical ventilation (MV) for at least 24 hours between January 20, 2020, and April 30, 2020. Atypical ARDS was defined as driving pressure is less than 15 cm H2O throughout the period of MV, suggesting compliant lung based on the currently available evidence (Amato, Marcelo BP, et al., 2015). If it was impossible to maintain driving pressure less than 15 cm H2O for more than two days, the case was defined as classic ARDS with low compliance. Patients who required mechanical ventilation not more than 24 hours or expired within 24 hours since intubated and those transferred to another hospital were excluded. Patients who received remdesivir were also excluded because 95% of the patients did not receive it during their index hospitalization. The outcome was adjusted by age, sex, days of onset to ICU, the severity of illness estimated by APACHE score, and severity of ARDS based on PaO2/FiO2 ratio. RESULTS: A total of 60 patients that required mechanical ventilation for COVID-19 induced ARDS during the study period were reviewed per inclusion and exclusion criteria. In-hospital mortality of 30 patients of the atypical ARDS group was 50% during the index hospitalization whereas it was 53 % for 30 patients of the classic ARDS group (p=0.80) when both were treated with the same ARDS protocol, including low tidal volume and higher PEEP. The average duration of mechanical ventilation, length of ICU and hospital stay was 10.23, 12.33, and 12.93 days for the atypical ARDS group, respectively, compared to 16.57, 18.33, and 19.33 for the classic ARDS group (p=0.003, 0.011, and 0.004, respectively). The classic ARDS group required prone positioning (67% vs. 37%;p=0.02) and use of paralytics (73% vs. 43%;p=0.018) more frequently compared to the atypical ARDS group. CONCLUSIONS: In this retrospective cohort study of 60 patients that required mechanical ventilation for COVID-19 induced ARDS between January 20, 2020, and April 30, 2020, in-hospital mortality was not significantly different between the atypical ARDS group and the classic ARDS group. However, the duration of mechanical ventilation, length of ICU and hospital stay was significantly shorter in the atypical ARDS group compared to the classic ARDS group. CLINICAL IMPLICATIONS: The difference in the duration of mechanical ventilation between the two groups may suggest a different pathophysiologic process and a need for a different approach to COVID-induced ARDS depending on lung compliance. DISCLOSURES: No relevant relationships by Mariam Charkviani, source=Web Response No relevant relationships by Chul Won Chung, source=Web Response No relevant relationships by Harvey Friedman, source=Web Response No relevant relationships by Jooseob Lee, source=Web Response No relevant relationships by Guillermo Rodriguez-Nava, source=Web Response No relevant relationships by Daniela Trelles Garcia, source=Web Response No relevant relationships by Maria Yanez-Bello, source=Web Response

Mechanical ventilation in COVID‐19: A physiological perspective

New Findings What is the topic of this review? This review presents the fundamental concepts of respiratory physiology and pathophysiology, with particular reference to lung mechanics and the pulmonary phenotype associated with severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection and subsequent coronavirus disease 2019 (COVID‐19) pneumonia. What advances does it highlight? The review provides a critical summary of the main physiological aspects to be considered for safe and effective mechanical ventilation in patients with severe COVID‐19 in the intensive care unit. Severe respiratory failure from coronavirus disease 2019 (COVID‐19) pneumonia not responding to non‐invasive respiratory support requires mechanical ventilation. Although ventilation can be a life‐saving therapy, it can cause further lung injury if airway pressure and flow and their timing are not tailored to the respiratory system mechanics of the individual patient. The pathophysiology of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection can lead to a pattern of lung injury in patients with severe COVID‐19 pneumonia typically associated with two distinct phenotypes, along a temporal and pathophysiological continuum, characterized by different levels of elastance, ventilation‐to‐perfusion ratio, right‐to‐left shunt, lung weight and recruitability. Understanding the underlying pathophysiology, duration of symptoms, radiological characteristics and lung mechanics at the individual patient level is crucial for the appropriate choice of mechanical ventilation settings to optimize gas exchange and prevent further lung injury. By critical analysis of the literature, we propose fundamental physiological and mechanical criteria for the selection of ventilation settings for COVID‐19 patients in intensive care units. In particular, the choice of tidal volume should be based on obtaining a driving pressure < 14 cmH2O, ensuring the avoidance of hypoventilation in patients with preserved compliance and of excessive strain in patients with smaller lung volumes and lower lung compliance. The level of positive end‐expiratory pressure (PEEP) should be informed by the measurement of the potential for lung recruitability, where patients with greater recruitability potential may benefit from higher PEEP levels. Prone positioning is often beneficial and should be considered early. The rationale for the proposed mechanical ventilation settings criteria is presented and discussed.

Spontaneous pneumomediastinum and pneumothorax in COVID-19 patients: A tertiary care experience.

IntroductionCOVID‐19 can occasionally complicate into spontaneous pneumothorax (SP) and/or spontaneous pneumomediastinum (SM). This study aims at exploring the occurrence of SP and or SM, risk factors, and outcomes in COVID‐19 patients.Materials and MethodsAll patients with COVID‐19, which complicated into SP and/or SM at Hamad Medical Corporation (the principal public healthcare provider in Qatar) from March to September 2020, were retrospectively enrolled. The clinical diagnosis was confirmed by CXR and CT. Between‐group comparisons were performed by using Chi‐square and t‐test. Differences were considered statistically significant at P ≤ .05.ResultsA total of 1100 patients were admitted, and 43 patients developed SP, SP + SM, or SM. Most patients were males (42/97.9%), and the most common comorbidity was diabetes mellitus (13/30.2%). All patients had acute respiratory distress syndrome (ARDS), and most patients had low lung compliance at the time of developing SP or SM. Twenty‐two of the patients developed SP (51.2%), 11 patients had both SP and SM (25.6%), and 10 patients had SM only (23.3%). There was no significant difference in the development of SP or SM and patients' gender or blood group or whether patients were on invasive or noninvasive ventilation or even the mortality (P > .05). Lung compliance was significantly (P < .05) lower in patients complicated with SP and or SM. Patients with SP required significantly higher (P < .001) chest drain insertion.ConclusionPatients with severe COVID‐19 pneumonia can complicate into SP and SM. These complications are more common in male diabetic patients. Patients with ARDS and having low lung compliance are at a higher risk of developing SP, SP + SM, or SM.

Non-invasive method to detect high respiratory effort and transpulmonary driving pressures in COVID-19 patients during mechanical ventilation

BackgroundHigh respiratory drive in mechanically ventilated patients with spontaneous breathing effort may cause excessive lung stress and strain and muscle loading. Therefore, it is important to have a reliable estimate of respiratory effort to guarantee lung and diaphragm protective mechanical ventilation. Recently, a novel non-invasive method was found to detect excessive dynamic transpulmonary driving pressure (∆PL) and respiratory muscle pressure (Pmus) with reasonable accuracy. During the Coronavirus disease 2019 (COVID-19) pandemic, it was impossible to obtain the gold standard for respiratory effort, esophageal manometry, in every patient. Therefore, we investigated whether this novel non-invasive method could also be applied in COVID-19 patients.Methods∆PL and Pmus were derived from esophageal manometry in COVID-19 patients. In addition, ∆PL and Pmus were computed from the occlusion pressure (∆Pocc) obtained during an expiratory occlusion maneuver. Measured and computed ∆PL and Pmus were compared and discriminative performance for excessive ∆PL and Pmus was assessed. The relation between occlusion pressure and respiratory effort was also assessed.ResultsThirteen patients were included. Patients had a low dynamic lung compliance [24 (20–31) mL/cmH2O], high ∆PL (25 ± 6 cmH2O) and high Pmus (16 ± 7 cmH2O). Low agreement was found between measured and computed ∆PL and Pmus. Excessive ∆PL > 20 cmH2O and Pmus > 15 cmH2O were accurately detected (area under the receiver operating curve (AUROC) 1.00 [95% confidence interval (CI), 1.00–1.00], sensitivity 100% (95% CI, 72–100%) and specificity 100% (95% CI, 16–100%) and AUROC 0.98 (95% CI, 0.90–1.00), sensitivity 100% (95% CI, 54–100%) and specificity 86% (95% CI, 42–100%), respectively). Respiratory effort calculated per minute was highly correlated with ∆Pocc (for esophageal pressure time product per minute (PTPes/min) r2 = 0.73; P = 0.0002 and work of breathing (WOB) r2 = 0.85; P < 0.0001).Conclusions∆PL and Pmus can be computed from an expiratory occlusion maneuver and can predict excessive ∆PL and Pmus in patients with COVID-19 with high accuracy.

Extracorporeal Membrane Oxygenation for COVID-19 Respiratory Distress Syndrome: An Italian Society for Cardiac Surgery Report.

An increased need of extracorporeal membrane oxygenation (ECMO) support is going to become evident as treatment of SARS-CoV-2 respiratory distress syndrome. This is the first report of the Italian Society for Cardiac Surgery (SICCH) on preliminary experience with COVID-19 patients receiving ECMO support. Data from 12 Italian hospitals participating in SICCH were retrospectively analyzed. Between March 1 and September 15, 2020, a veno-venous (VV) ECMO system was installed in 67 patients (94%) and a veno-arterio-venous ECMO in four (6%). Five patients required VA ECMO after initial weaning from VV ECMO. Thirty (42.2%) patients were weaned from ECMO, while 39 (54.9%) died on ECMO, and six (8.5%) died after ECMO removal. Overall hospital survival was 36.6% (n = 26). Main causes of death were multiple organ failure (n = 14, 31.1%) and sepsis (n = 11, 24.4%). On multivariable analysis, predictors of death while on ECMO support were older age (p = 0.048), elevated pre-ECMO C-reactive protein level (p = 0.048), higher positive end-expiratory pressure on ventilator (p = 0.036) and lower lung compliance (p = 0.032). If the conservative treatment is not effective, ECMO support might be considered as life-saving rescue therapy for COVID-19 refractory respiratory failure. However warm caution and thoughtful approaches for timely detection and treatment should be taken for such a delicate patients population.

Restoration of surfactant activity by polymyxin B in lipopolysaccharide-potentiated injury of immature rabbit lungs

During postnatal adaptation pulmonary surfactant may be inactivated by lipopolysaccharide (LPS). We evaluated the effect of surfactant therapy in combination with antibiotic polymyxin B (PxB) in double-hit model of neonatal lung injury. Surfactant (poractant alfa, Curosurf) was exposed to smooth (S) LPS without/with PxB and tested in captive bubble surfactometer. Preterm rabbits received intratracheally saline (control) or S-LPS and were ventilated with 100% oxygen. After 30 min, LPS-treated animals received no treatment, or surfactant (200 mg/kg) without/with 3% PxB; controls received the same dose of surfactant. Animals were ventilated for further 2 h. In vitro, addition of 5% S-LPS to surfactant increased minimum surface tension (γmin) and addition of 1–3% PxB to surfactant/S-LPS mixture restored γmin to low values. Animals only given S-LPS had lower lung compliance and lung gas volume (LGV) compared to surfactant groups. Treatment with surfactant/PxB, but not with surfactant only, restored LGV. Addition of PxB to the surfactant increased the alveolar expansion. S-LPS interferes with surface activity of the pulmonary surfactant and PxB improves the resistance of surfactant to LPS-induced inactivation. In our neonatal model of respiratory distress syndrome surfactant gives positive response even in simultaneous exposure to S-LPS, when enriched with PxB.

COVID-19: A Review of Current Evidence on Phylogenetics and Etiopathogenesis

COVID-19 represents the latest pandemic caused by the SARS-CoV-2 coronavirus. Coronaviruses are RNA viruses that cause a largely viral mediated immune-related syndrome similar to the SARS epidemic. Following metagenomic sequencing, SARS-CoV-2 closely resembles SARS-CoV (79% similarity) and MERS-CoV virus (50% similarity). Despite this, clinical observations have found varying degrees of infectivity and pathogenesis amongst these viruses. Phylogenetic origins of SARS-CoV-2 have found connections to bats and pangolins as possible zoonotic reservoirs. It enters the host cells via the receptor binding site of the ACE-2 receptor. Upon entering the host cells, cytopathic effects and interruption of respiratory cilia occur with a resultant cascade of pro-inflammatory cytokines and chemokines. Common clinical features of COVID-19 include fever, cough and fatigue. COVID-19 infected patients also present with various gastrointestinal, gustatory, dermatologic, ocular, cardiovascular, neurologic and coagulopathic manifestations. Dyspnea, sore throat, nasal congestion, musculoskeletal pain, headaches and chills were also observed. Emerging data supports that COVID 19 has disproportionately affected specific ethnic groups, particularly racial minorities for various health and institutional reasons. It is estimated around 5% of all cases are severe, presenting with respiratory failure, shock, acute respiratory syndrome and arrhythmias. Co-infection with other pathogens was also seen with various other viruses such as rhinoviruses, respiratory syncytial virus and other coronaviruses. COVID-19 is able to spread asymptomatically and causes slightly different manifestations in pregnant ladies and the pediatric populations. ARDS in COVID-19 patients is suspected to be a unique clinical entity as lung function testing found high driving pressures with abnormally low lung compliance and low lung recruitability. This requires a unique approach to ventilating COVID-19 ARDS patients. In conclusion, new emerging data will require healthcare professionals to adapt and more studies are required to overcome this critical pandemic.

New indicators for optimal lung recruitment during high frequency oscillator ventilation.

A two-step animal distress model study was designed; in the first-step (ex vivo model), the animal's lungs were isolated to visually check lung recruitment and, in the second one (in vivo model), they were checked through arterial oxygen partial pressure improvement. Baseline measurements were performed, ventilation was set for 10 min and followed by bronchoalveolar lavage with isotonic saline to induce depletion of surfactant and thereby achieve a low compliance lung model. The high-frequency tidal volume and frequency remained constant and the MAP was increased by 2 cmH2 O (ex vivo) and 3 cmH2 O steps (in vivo) every 2 min. Changes in ΔPhf to achieve the fixed volume were recorded at the end of each interval to describe the maximum drop point as the recruitment point. Fourteen Wistar Han rats were included, seven on each sub-study described. After gradual MAP increments, a progressive decrease in ΔPhf related to recruited lung regions was visually demonstrated. In the in vivo model we detected a significant comparative decrease of ΔPhf, when measured against the previous value, after reaching a MAP of 11 cmH2 O up to 17 cmH2 O, correlating with a significant improvement in oxygenation. The changes in ∆Phf, linked to a progressive increase in MAP during HFOV-VG, might identify optimal lung recruitment and could potentially be used as an additional lung recruitment marker.

Are the "critical" inspiratory constraints actually decisive to limit exercise tolerance in COPD?

The concept of critical inspiratory constraints is key to the modern understanding of exercise pathophysiology in patients with moderate-to-severe COPD https://bit.ly/2A6bCxD

Using the Systems Engineering Initiative for Patient Safety (SEIPS) model to describe critical care nursing during the SARS-CoV-2 pandemic (2020).

Using the Systems Engineering Initiative for Patient Safety (SEIPS) model to describe critical care nursing during the SARS-CoV-2 pandemic (2020).

T-piece resuscitators: can they provide safe ventilation in a low compliant newborn lung?

BackgroundT-piece resuscitators (TPRs) are used for primary newborn resuscitation in birthing and emergency rooms worldwide. A recent study has shown spikes in peak inflation pressure (PIP) over set values with...

Establishment of functional residual capacity at birth: Observational study of 821 neonatal resuscitations

Aim of the studyEstablishing functional residual capacity (FRC) during positive pressure ventilation (PPV) of apnoeic neonates is critical for survival. This may be difficult due to liquid-filled airways contributing to low lung compliance. The objectives were to describe initial PPV, changes in lung compliance and establishment of FRC in near-term/term neonates ≥36 weeks gestation at birth. MethodsObservational study of all neonatal resuscitations between 01.07.13 and 30.06.18 in a Tanzanian referral hospital. Perinatal events and characteristics were observed and recorded by trained research assistants. PPV were performed using self-inflating bag-masks without positive end-expiratory pressure (PEEP). Ventilation signals (pressure/flow), expired CO2 (ECO2) and heart rate were recorded by resuscitation monitors. Results19,587 neonates were born, 1451 received PPV, of these 821 of median (p25, p75) birthweight 3180 (2844, 3500) grams and gestation 38 (37, 40) weeks had ≥20 ventilations and complete datasets. There was a significant increase in expired volume (from 3.3 to 6.0 ml/kg), ECO2 (0.3–2.4%), lung compliance (0.13–0.19 ml/kg/mbar) and heart rate (109–138 beats/min) over the first 20 PPVs. Inflation volume, time, and peak inflation pressure (PIP) were stable around 12–13 ml/kg, 0.45 s, and 36 mbar, respectively. ConclusionsThe combination of increasing expired volumes, ECO2, and heart rate with decreasing inflation/expired volume ratios and constant PIP, suggests establishment of FRC during the first 20 PPVs in near-term/term neonates using a self-inflating bag-mask without PEEP, the most common device worldwide for ventilating non-breathing neonates. Initial lung compliance is low, and with short inflation times, higher than recommended PIP seem necessary to deliver adequate tidal volumes.