Hourly Analysis of Mechanical Ventilation Parameters in Critically Ill Adult Covid-19 Patients: Association with Mortality

Abstract Objective: there exists controversy about the pathophysiology and lung mechanics of COVID-19 associated ARDS, because some report severe hypoxemia with preserved respiratory system mechanics, contrasting with “classic” ARDS. We performed a detailed hourly analysis of the characteristics and time course of lung mechanics and biochemical analysis of patients requiring invasive mechanical ventilation for COVID-19-associated ARDS, comparing survivors and non-survivors.Methods and measurements: retrospective analysis of the data stored in the ICU information system of patients admitted in our hospital ICU that required invasive mechanical ventilation due to confirmed SARS-CoV-2 pneumonia between March 5th and April 30th, 2020. We compare respiratory system mechanics and gas exchange during the first ten days of IMV, discriminating volume and pressure controlled modes, between ICU survivors and non-survivors.Results: 140 patients were analyzed, analyzing 11,138 respiratory mechanics recordings. Global mortality was 38.6%. Multivariate analysis showed that age (OR 1,092, 95% (CI 1,014-1,176)), previous use of ACEI/ARBs (OR 4,612, (95% CI 1,19-17,84)) and need of renal replacement therapies (OR 10,15, (95% CI 1,58-65,11)) were associated with higher mortality. Respiratory variables start to diverge significantly between survivors and non-survivors after the 96 to 120 hours from mechanical ventilation initiation, particularly respiratory system compliance. In non survivors, mechanical power at 24 and 96 hs was higher regardless ventilatory mode. Conclusions: in patients admitted for SARS-CoV-2 pneumonia and requiring mechanical ventilation, non survivors have different respiratory system mechanics than survivors in the first 10 days of ICU admission. We propose a checkpoint at 96-120 hs to assess patients` improvement or worsening in order to consider escalating to extracorporeal therapies.“TAKE HOME MESSAGE”: assessing respiratory mechanics in the first 96-120 hs from ICU admission could predict the outcome of Covid-19 patients under mechanical ventilation.

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Mechanical ventilation parameters in critically ill COVID-19 patients: a scoping review

Critical Care ◽

10.1186/s13054-021-03536-2 ◽

2021 ◽

Vol 25 (1) ◽

Author(s):

Giacomo Grasselli ◽

Emanuele Cattaneo ◽

Gaetano Florio ◽

Mariachiara Ippolito ◽

Alberto Zanella ◽

...

Keyword(s):

Mechanical Ventilation ◽

Critically Ill ◽

Respiratory System ◽

Scoping Review ◽

Respiratory Mechanics ◽

Neuromuscular Blocking ◽

Arterial Oxygen ◽

Icu Admission ◽

Number Of Patients ◽

Optimal Setting

Abstract Background The mortality of critically ill patients with COVID-19 is high, particularly among those receiving mechanical ventilation (MV). Despite the high number of patients treated worldwide, data on respiratory mechanics are currently scarce and the optimal setting of MV remains to be defined. This scoping review aims to provide an overview of available data about respiratory mechanics, gas exchange and MV settings in patients admitted to intensive care units (ICUs) for COVID-19-associated acute respiratory failure, and to identify knowledge gaps. Main text PubMed, EMBASE, and MEDLINE databases were searched from inception to October 30, 2020 for studies providing at least one ventilatory parameter collected within 24 h from the ICU admission. The quality of the studies was independently assessed using the Newcastle–Ottawa Quality Assessment Form for Cohort Studies. A total of 26 studies were included for a total of 14,075 patients. At ICU admission, positive end expiratory pressure (PEEP) values ranged from 9 to 16.5 cm of water (cmH2O), suggesting that high levels of PEEP were commonly used for setting MV for these patients. Patients with COVID-19 are severely hypoxemic at ICU admission and show a median ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (PaO2/FiO2) ranging from 102 to 198 mmHg. Static respiratory system compliance (Crs) values at ICU admission were highly heterogenous, ranging between 24 and 49 ml/cmH2O. Prone positioning and neuromuscular blocking agents were widely used, ranging from 17 to 81 and 22 to 88%, respectively; both rates were higher than previously reported in patients with “classical” acute respiratory distress syndrome (ARDS). Conclusions Available data show that, in mechanically ventilated patients with COVID-19, respiratory mechanics and MV settings within 24 h from ICU admission are heterogeneous but similar to those reported for “classical” ARDS. However, to date, complete data regarding mechanical properties of respiratory system, optimal setting of MV and the role of rescue treatments for refractory hypoxemia are still lacking in the medical literature.

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Lung Mechanics in Type L CoVID-19 Pneumonia: A Pseudo-Normal ARDS.

10.21203/rs.3.rs-37028/v1 ◽

2020 ◽

Author(s):

Lorenzo Viola ◽

Emanuele Russo ◽

Marco Benni ◽

Emiliano Gamberini ◽

Alessandro Circelli ◽

...

Keyword(s):

Mechanical Ventilation ◽

Acute Respiratory Distress Syndrome ◽

Respiratory Distress Syndrome ◽

Respiratory Distress ◽

Respiratory System ◽

Respiratory Insufficiency ◽

Distress Syndrome ◽

Lung Mechanics ◽

Prone Positioning ◽

Respiratory System Mechanics

Abstract Since its outbreak, in January, 2020, it has been clear that CoVID-19 pneumonia is atypical. Despite a full concordance to Berlin criteria for Acute Respiratory Distress Syndrome (ARDS), respiratory system mechanics is preserved [1]. Mechanical ventilation and muscular paralysis are recommended in worsening respiratory insufficiency [2]; in a substantial number of cases, prone positioning significantly improves oxygenation.

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Improvement in upright and supine lung mechanics with bariatric surgery affects bronchodilator responsiveness and sleep quality

Journal of Applied Physiology ◽

10.1152/japplphysiol.00694.2017 ◽

2018 ◽

Vol 125 (4) ◽

pp. 1305-1314 ◽

Cited By ~ 3

Author(s):

Ubong Peters ◽

Gail Dechman ◽

Paul Hernandez ◽

Swati Bhatawadekar ◽

James Ellsmere ◽

...

Keyword(s):

Weight Loss ◽

Sleep Quality ◽

Respiratory System ◽

Severe Obesity ◽

Respiratory Mechanics ◽

Lung Mechanics ◽

Poor Sleep ◽

Poor Sleep Quality ◽

Respiratory System Mechanics ◽

Bronchodilator Responsiveness

Obesity and weight loss have complex effects on respiratory physiology, but these have been insufficiently studied, particularly at early time points following weight loss surgery and in the supine position. We evaluated 15 female participants with severe obesity before and 5 wk and 6 mo after bariatric surgery using the Pittsburgh Sleep Quality Index (PSQI), spirometry, plethysmography, and oscillometry to measure respiratory system mechanics. Oscillometry and spirometry were conducted in the upright and supine position and before and after bronchodilation with 200 µg of salbutamol. At 5 wk postsurgery, weight loss was 11.9 kg (SD 2.7) with no effect on spirometric outcomes and a slight effect on oscillometric outcomes. However, at 6 mo weight loss was 21.4 kg (SD 7.1) with a 14.1% (SD 6.1) and 17.8 (5.4)% reduction in upright and supine respiratory system resistance (Rrs),6, respectively. Respiratory system elastance also decreased by 25.7% (SD 9.4) and 20.2 (SD 7.2)% in the upright and supine positions. No changes were observed in spirometry, but sleep quality improved from PSQI of 8.4 (SD 3.5) to 4.1 (SD 2.9). Bronchodilator responsiveness was low at baseline but increased significantly after surgery, and this response was comparable to the improvement in Rrs produced by weight loss. Modeling the impedance spectra with a two-compartment model demonstrated that improvements in lung mechanics with weight loss begin in the upper or central compartment of the lungs and progress to include the peripheral compartment. Respiratory mechanics are impaired in individuals with severe obesity and is associated with poor sleep quality, but these improved substantially with weight loss. Our data provide new evidence that individuals with severe obesity may have poor sleep quality because of abnormal respiratory mechanics that weight loss improves. NEW & NOTEWORTHY This is the first study to quantify the degree of weight loss-induced improvements in respiratory system mechanics in both upright and supine positions, and its association with bronchodilator responsiveness and sleep quality at multiple time points. Weight loss induced large improvements in upright and supine respiratory system mechanics with corresponding improvements in bronchodilator responsiveness and sleep quality. Using mathematical modeling, we demonstrate that these improvements begin in the central airways and progress to include the lung periphery.

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Respiratory mechanics and gas exchanges in the early course of COVID-19 ARDS: a hypothesis-generating study

Annals of Intensive Care ◽

10.1186/s13613-020-00716-1 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 8

Author(s):

J.-L. Diehl ◽

N. Peron ◽

R. Chocron ◽

B. Debuc ◽

E. Guerot ◽

...

Keyword(s):

Mechanical Ventilation ◽

Dead Space ◽

Respiratory Mechanics ◽

Invasive Mechanical Ventilation ◽

Endothelial Damage ◽

Circulating Endothelial Cells ◽

Pulmonary Mechanics ◽

High Peep ◽

Gas Exchanges ◽

Physiological Dead Space

Abstract Rationale COVID-19 ARDS could differ from typical forms of the syndrome. Objective Pulmonary microvascular injury and thrombosis are increasingly reported as constitutive features of COVID-19 respiratory failure. Our aim was to study pulmonary mechanics and gas exchanges in COVID-2019 ARDS patients studied early after initiating protective invasive mechanical ventilation, seeking after corresponding pathophysiological and biological characteristics. Methods Between March 22 and March 30, 2020 respiratory mechanics, gas exchanges, circulating endothelial cells (CEC) as markers of endothelial damage, and D-dimers were studied in 22 moderate-to-severe COVID-19 ARDS patients, 1 [1–4] day after intubation (median [IQR]). Measurements and main results Thirteen moderate and 9 severe COVID-19 ARDS patients were studied after initiation of high PEEP protective mechanical ventilation. We observed moderately decreased respiratory system compliance: 39.5 [33.1–44.7] mL/cmH2O and end-expiratory lung volume: 2100 [1721–2434] mL. Gas exchanges were characterized by hypercapnia 55 [44–62] mmHg, high physiological dead-space (VD/VT): 75 [69–85.5] % and ventilatory ratio (VR): 2.9 [2.2–3.4]. VD/VT and VR were significantly correlated: r2 = 0.24, p = 0.014. No pulmonary embolism was suspected at the time of measurements. CECs and D-dimers were elevated as compared to normal values: 24 [12–46] cells per mL and 1483 [999–2217] ng/mL, respectively. Conclusions We observed early in the course of COVID-19 ARDS high VD/VT in association with biological markers of endothelial damage and thrombosis. High VD/VT can be explained by high PEEP settings and added instrumental dead space, with a possible associated role of COVID-19-triggered pulmonary microvascular endothelial damage and microthrombotic process.

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Effect of pressure-controlled ventilation-volume guaranteed mode combined with individualized positive end-expiratory pressure on respiratory mechanics, oxygenation and lung injury in patients undergoing laparoscopic surgery in Trendelenburg position

Journal of Clinical Monitoring and Computing ◽

10.1007/s10877-021-00750-9 ◽

2021 ◽

Author(s):

Jianli Li ◽

Saixian Ma ◽

Xiujie Chang ◽

Songxu Ju ◽

Meng Zhang ◽

...

Keyword(s):

Laparoscopic Surgery ◽

Lung Injury ◽

Respiratory Mechanics ◽

Lung Mechanics ◽

Trial Registry ◽

Positive End Expiratory Pressure ◽

Clinical Trial Registry ◽

Trendelenburg Position ◽

Pressure Controlled Ventilation ◽

Pressure Controlled

AbstractThe study aimed to investigate the efficacy of PCV-VG combined with individual PEEP during laparoscopic surgery in the Trendelenburg position. 120 patients were randomly divided into four groups: VF group (VCV plus 5cmH2O PEEP), PF group (PCV-VG plus 5cmH2O PEEP), VI group (VCV plus individual PEEP), and PI group (PCV-VG plus individual PEEP). Pmean, Ppeak, Cdyn, PaO2/FiO2, VD/VT, A-aDO2 and Qs/Qt were recorded at T1 (15 min after the induction of anesthesia), T2 (60 min after pneumoperitoneum), and T3 (5 min at the end of anesthesia). The CC16 and IL-6 were measured at T1 and T3. Our results showed that the Pmean was increased in VI and PI group, and the Ppeak was lower in PI group at T2. At T2 and T3, the Cdyn of PI group was higher than that in other groups, and PaO2/FiO2 was increased in PI group compared with VF and VI group. At T2 and T3, A-aDO2 of PI and PF group was reduced than that in other groups. The Qs/Qt was decreased in PI group compared with VF and VI group at T2 and T3. At T2, VD/VT in PI group was decreased than other groups. At T3, the concentration of CC16 in PI group was lower compared with other groups, and IL-6 level of PI group was decreased than that in VF and VI group. In conclusion, the patients who underwent laparoscopic surgery, PCV-VG combined with individual PEEP produced favorable lung mechanics and oxygenation, and thus reducing inflammatory response and lung injury.Clinical Trial registry: chictr.org. identifier: ChiCTR-2100044928

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Lung Mechanics in Type L CoVID-19 Pneumonia: A Pseudo-Normal ARDS.

10.21203/rs.3.rs-78234/v1 ◽

2020 ◽

Author(s):

Lorenzo Viola ◽

Emanuele Russo ◽

Marco Benni ◽

Emiliano Gamberini ◽

Alessandro Circelli ◽

...

Keyword(s):

Mechanical Properties ◽

Respiratory System ◽

Respiratory Mechanics ◽

Blood Gases ◽

Lung Mechanics ◽

Prone Positioning ◽

Arterial Blood Gases ◽

Arterial Blood ◽

Esophageal Balloon ◽

Early Phases

Abstract Background. This study was conceived to provide systematic data about lung mechanics during early phases of CoVID-19 pneumonia, as long as to explore its variations during prone positioning. Methods. We enrolled four patients hospitalized in the Intensive Care Unit of “M. Bufalini” hospital, Cesena (Italy); after the positioning of an esophageal balloon, we measured mechanical power, respiratory system and transpulmonary parameters and arterial blood gases every 6 hours, just before decubitus change and 1 hour after prono-supination. Results. Both respiratory system and transpulmonary compliance and driving pressure confirmed the pseudo-normal respiratory mechanics of early CoVID-19 pneumonia (respectively, CRS 40.8 ml/cmH2O and DPRS 9.7 cmH2O; CL 53.1 ml/cmH2O and DPL 7.9 cmH2O). Interestingly, prone positioning involved a worsening in respiratory mechanical properties (CRS,SUP 56.3 ml/cmH2O and CRS,PR 41.5 ml/cmH2O – P 0.37; CL,SUP 80.8 ml/cmH2O and CL,PR 53.2 ml/cmH2O – P 0.23). Conclusions. Despite the severe ARDS pattern, respiratory system and lung mechanical properties during CoVID-19 pneumonia are pseudo-normal and tend to worsen during pronation. Trial registration. Restrospectively registered.

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Inflammatory cellular response to mechanical ventilation in elastase-induced experimental emphysema: role of pre-existing alveolar macrophages infiltration

10.1101/205989 ◽

2017 ◽

Author(s):

Anahita Rouze ◽

Guillaume Voiriot ◽

Elise Guivarch ◽

Françoise Roux ◽

Jeanne Tran Van Nhieu ◽

...

Keyword(s):

Mechanical Ventilation ◽

Alveolar Macrophages ◽

Pulmonary Emphysema ◽

Lung Inflammation ◽

Cellular Response ◽

Invasive Mechanical Ventilation ◽

Inflammatory Cells ◽

Chord Length ◽

Lung Mechanics ◽

Chronic Obstructive

ABSTRACTBackgroundAn excessive pulmonary inflammatory response could explain the poor prognosis of chronic obstructive pulmonary disease (COPD) patients submitted to invasive mechanical ventilation. The aim of this study was to evaluate the response to normal tidal volume (Vt) mechanical ventilation in a murine model of pulmonary emphysema, which represents the alveolar component of COPD. In this model, two time points associated with different levels of lung inflammation but similar lung destruction, were analyzed.MethodsC57BL/6 mice received a tracheal instillation of 5 IU of porcine pancreatic elastase (Elastase mice) or the same volume of saline (Saline mice). Fourteen (D14) and 21 (D21) days after instillation, mice were anesthetized, intubated, and either mechanically ventilated (MV) with a normal Vt (8 mL/kg) or maintained on spontaneous ventilation (SV) during two hours. We analyzed respiratory mechanics, emphysema degree (mean chord length by lung histological analysis), and lung inflammation (bronchoalveolar lavage (BAL) cellularity, proportion and activation of total lung inflammatory cells by flow cytometry).ResultsAs compared with Saline mice, Elastase mice showed a similarly increased mean chord length and pulmonary compliance at D14 and D21, while BAL cellularity was comparable between groups. Lung mechanics was similarly altered during mechanical ventilation in Elastase and Saline mice. Activated alveolar macrophages CD11bmid were present in lung parenchyma in both Elastase SV mice and Elastase MV mice at D14 but were absent at D21 and in Saline mice, indicating an inflammatory state with elastase at D14 only. At D14, Elastase MV mice showed a significant increase in percentage of neutrophils concomitant with a decrease in percentage of alveolar macrophages in total lung, as compared with Elastase SV mice. Furthermore, alveolar macrophages of Elastase MV mice at D14 overexpressed Gr1, and monocytes showed a trend to overexpression of CD62L, compared with Elastase SV mice.ConclusionsIn an elastase-induced model of pulmonary emphysema, normal Vt mechanical ventilation produced an increase in the proportion of pulmonary neutrophils, and an activation of alveolar macrophages and pulmonary monocytes. This response was observed only when the emphysema model showed an underlying inflammation (D14), reflected by the presence of activated alveolar macrophages CD11bmid.

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Airway Closure during Surgical Pneumoperitoneum in Obese Patients

Anesthesiology ◽

10.1097/aln.0000000000002662 ◽

2019 ◽

Vol 131 (1) ◽

pp. 58-73 ◽

Cited By ~ 22

Author(s):

Domenico Luca Grieco ◽

Gian Marco Anzellotti ◽

Andrea Russo ◽

Filippo Bongiovanni ◽

Barbara Costantini ◽

...

Keyword(s):

Lung Volume ◽

Respiratory Mechanics ◽

Lung Mechanics ◽

Control Group ◽

Obese Patients ◽

Airway Closure ◽

Alveolar Pressure ◽

Opening Pressure ◽

Airway Opening ◽

Pressure Controlled

AbstractEditor’s PerspectiveWhat We Already Know about This TopicWhat This Article Tells Us That Is NewBackgroundAirway closure causes lack of communication between proximal airways and alveoli, making tidal inflation start only after a critical airway opening pressure is overcome. The authors conducted a matched cohort study to report the existence of this phenomenon among obese patients undergoing general anesthesia.MethodsWithin the procedures of a clinical trial during gynecological surgery, obese patients underwent respiratory/lung mechanics and lung volume assessment both before and after pneumoperitoneum, in the supine and Trendelenburg positions, respectively. Among patients included in this study, those exhibiting airway closure were compared to a control group of subjects enrolled in the same trial and matched in 1:1 ratio according to body mass index.ResultsEleven of 50 patients (22%) showed airway closure after intubation, with a median (interquartile range) airway opening pressure of 9 cm H2O (6 to 12). With pneumoperitoneum, airway opening pressure increased up to 21 cm H2O (19 to 28) and end-expiratory lung volume remained unchanged (1,294 ml [1,154 to 1,363] vs. 1,160 ml [1,118 to 1,256], P = 0.155), because end-expiratory alveolar pressure increased consistently with airway opening pressure and counterbalanced pneumoperitoneum-induced increases in end-expiratory esophageal pressure (16 cm H2O [15 to 19] vs. 27 cm H2O [23 to 30], P = 0.005). Conversely, matched control subjects experienced a statistically significant greater reduction in end-expiratory lung volume due to pneumoperitoneum (1,113 ml [1,040 to 1,577] vs. 1,000 ml [821 to 1,061], P = 0.006). With airway closure, static/dynamic mechanics failed to measure actual lung/respiratory mechanics. When patients with airway closure underwent pressure-controlled ventilation, no tidal volume was inflated until inspiratory pressure overcame airway opening pressure.ConclusionsIn obese patients, complete airway closure is frequent during anesthesia and is worsened by Trendelenburg pneumoperitoneum, which increases airway opening pressure and alveolar pressure: besides preventing alveolar derecruitment, this yields misinterpretation of respiratory mechanics and generates a pressure threshold to inflate the lung that can reach high values, spreading concerns on the safety of pressure-controlled modes in this setting.

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Respiratory Mechanics

10.1093/med/9780190670085.003.0001 ◽

2017 ◽

Author(s):

John W. Kreit

Keyword(s):

Mechanical Ventilation ◽

Respiratory System ◽

Respiratory Mechanics ◽

Pressure Change ◽

Equation Of Motion ◽

Positive End Expiratory Pressure ◽

Elastic Recoil ◽

Viscous Forces ◽

Equilibrium Volume ◽

Complex Process

Ventilation can occur only when the respiratory system expands above and then returns to its resting or equilibrium volume. This is just another way of saying that ventilation depends on our ability to breathe. Although breathing requires very little effort and even less thought, it’s nevertheless a fairly complex process. Respiratory Mechanics reviews the interaction between applied and opposing forces during spontaneous and mechanical ventilation. It discusses elastic recoil, viscous forces, compliance, resistance, and the equation of motion and the time constant of the respiratory system. It also describes how and why pleural, alveolar, lung transmural, intra-abdominal, and airway pressure change during spontaneous and mechanical ventilation, and the effect of applied positive end-expiratory pressure (PEEP).

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Techniques for measuring respiratory mechanics: an analytic approach with a viscoelastic model

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.5.2373 ◽

1993 ◽

Vol 74 (5) ◽

pp. 2373-2379 ◽

Cited By ~ 7

Author(s):

A. M. Lorino ◽

A. Harf

Keyword(s):

Mechanical Ventilation ◽

Mechanical Behavior ◽

Respiratory System ◽

Respiratory Mechanics ◽

Homogeneous Model ◽

Viscoelastic Model ◽

Normal Subjects ◽

Inspiratory Time ◽

Airway Occlusion ◽

Analytic Expressions

A homogeneous model with stress relaxation that is described by a pure viscoelastic component was recently proposed to describe the mechanical behavior of the respiratory system during mechanical ventilation (Bates et al. J. Appl. Physiol. 67: 2276–2285, 1989). With the use of this model, analytic expressions of the pressure in response to typical volume inputs are developed, and the recently published studies relating to the influence of the ventilatory pattern on respiratory mechanics are reviewed and analyzed. The analytic expression of pressure responses to rapid airway occlusion following constant-flow inflation and to sinusoidal volume oscillations allows prediction of most of the reported results. The theoretical analysis suggests that in normal subjects the observed flow and volume dependencies of respiratory mechanics are, in fact, illustrations of the dependence of the viscoelastic resistance on inspiratory time and respiratory frequency. Thus the homogeneous viscoelastic model appears suitable to describe respiratory system mechanical behavior under mechanical ventilation.

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