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1.
Am J Respir Crit Care Med ; 2022 May 24.
Article in English | MEDLINE | ID: covidwho-1857982

ABSTRACT

RATIONALE: Weaning from veno-venous extracorporeal membrane oxygenation (VV-ECMO) is based on oxygenation and not on carbon dioxide elimination. OBJECTIVE: To predict readiness to wean from VV-ECMO Methods: In this multicenter study of mechanically ventilated adults with severe acute respiratory distress syndrome (ARDS) receiving VV-ECMO, we investigated a variable based on CO2 elimination. The study included a prospective interventional study of a physiological cohort (n=26), and a retrospective clinical cohort (n=638). MEASUREMENTS AND MAIN RESULTS: Weaning failure in the clinical and physiological cohorts were respectively 37% and 42%. The main cause of failure in the physiological cohort was high inspiratory effort or respiratory rate. All patients exhaled similar amounts of CO2 but in patients who failed the weaning trial minute ventilation was higher to maintain the PaCO2 unchanged. The effort to eliminate one unit-volume of CO2, was double in failing patients [68·9 (42·4-123) vs. 39 (20·1-57) [cmH2O/(L/min)], p=0.007], owing to the higher physiological dead space [68 (58.73) % vs. 54 (41,.64) %; p=0.012]. PetCO2/PaCO2 ratio was a clinical variable strongly associated with weaning outcome at baseline was the, AUC: 0.87 (95%CI 0·71 - one). Similarly, the PetCO2/PaCO2 ratio was associated with weaning outcome in the "clinical cohort" both pre-weaning trial (OR 4·14; 95% CI 1·32 - 12·2; p=0·015), and at a sweep gas flow of zero (OR 13·1; 95% CI 4-44·4; p<0·001). CONCLUSION: The primary reason for weaning failure from VV-ECMO is high effort to eliminate CO2. A higher PetCO2/PaCO2 ratio was associated with greater likelihood of weaning from VV-ECMO.

2.
Crit Care Med ; 50(5): 873-875, 2022 05 01.
Article in English | MEDLINE | ID: covidwho-1672321
4.
Crit Care Explor ; 3(11): e0593, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1541580

ABSTRACT

We describe seven proned patients with coronavirus disease 2019-related acute respiratory distress syndrome in whom a paradoxical decrease in driving pressure reversibly occurred during passive, volume-controlled ventilation when compressing the lower back by a sustained "dorsal push." We offer a potential explanation for these unexpected observations and suggest the possible importance of eliciting this response for lung-protective ventilation of similar patients. DESIGN/SETTING: Case series at a single teaching hospital affiliated with the University of Minnesota. Measurements were recorded from continuously monitored airway pressure and flow data. PATIENTS: Nonconsecutive and nonrandomized sample of coronavirus disease 2019 acute respiratory distress syndrome patients who were already prone and paralyzed for optimized lung protective clinical management while inhaling pure oxygen. INTERVENTIONS: Sustained, firm manual pressure applied over the lower back in all patients, followed by abdominal binding in a subset of these. MEASUREMENTS AND MAIN RESULTS: Respiratory system driving pressure declined and respiratory system compliance improved in seven patients with the dorsal push maneuver. In a subset of four of these, abdominal binding sustained those improvements over >3 hours. CONCLUSIONS: Sustained compressive force applied to the dorsum of the passive and prone patient with severe respiratory failure due to coronavirus disease pneumonia may elicit a paradoxical response characterized by improved compliance and for a given tidal volume, lower plateau, and driving pressures. Such findings, which suggest end-tidal overinflation within the aerated part of the diseased lung despite the already compressed anterior chest wall of prone positioning, complement and extend those observations recently described for the supine position in coronavirus disease 2019 acute respiratory distress syndrome.

5.
Intensive Care Med ; 48(1): 56-66, 2022 01.
Article in English | MEDLINE | ID: covidwho-1536292

ABSTRACT

PURPOSE: This study aimed at investigating the mechanisms underlying the oxygenation response to proning and recruitment maneuvers in coronavirus disease 2019 (COVID-19) pneumonia. METHODS: Twenty-five patients with COVID-19 pneumonia, at variable times since admission (from 1 to 3 weeks), underwent computed tomography (CT) lung scans, gas-exchange and lung-mechanics measurement in supine and prone positions at 5 cmH2O and during recruiting maneuver (supine, 35 cmH2O). Within the non-aerated tissue, we differentiated the atelectatic and consolidated tissue (recruitable and non-recruitable at 35 cmH2O of airway pressure). Positive/negative response to proning/recruitment was defined as increase/decrease of PaO2/FiO2. Apparent perfusion ratio was computed as venous admixture/non aerated tissue fraction. RESULTS: The average values of venous admixture and PaO2/FiO2 ratio were similar in supine-5 and prone-5. However, the PaO2/FiO2 changes (increasing in 65% of the patients and decreasing in 35%, from supine to prone) correlated with the balance between resolution of dorsal atelectasis and formation of ventral atelectasis (p = 0.002). Dorsal consolidated tissue determined this balance, being inversely related with dorsal recruitment (p = 0.012). From supine-5 to supine-35, the apparent perfusion ratio increased from 1.38 ± 0.71 to 2.15 ± 1.15 (p = 0.004) while PaO2/FiO2 ratio increased in 52% and decreased in 48% of patients. Non-responders had consolidated tissue fraction of 0.27 ± 0.1 vs. 0.18 ± 0.1 in the responding cohort (p = 0.04). Consolidated tissue, PaCO2 and respiratory system elastance were higher in patients assessed late (all p < 0.05), suggesting, all together, "fibrotic-like" changes of the lung over time. CONCLUSION: The amount of consolidated tissue was higher in patients assessed during the third week and determined the oxygenation responses following pronation and recruitment maneuvers.


Subject(s)
COVID-19 , Respiratory Distress Syndrome , Humans , Lung/diagnostic imaging , Prone Position , Prospective Studies , Pulmonary Gas Exchange , SARS-CoV-2
6.
Eur Respir Rev ; 30(162)2021 Dec 31.
Article in English | MEDLINE | ID: covidwho-1477254

ABSTRACT

Coronavirus disease 2019 (COVID-19) pneumonia is an evolving disease. We will focus on the development of its pathophysiologic characteristics over time, and how these time-related changes determine modifications in treatment. In the emergency department: the peculiar characteristic is the coexistence, in a significant fraction of patients, of severe hypoxaemia, near-normal lung computed tomography imaging, lung gas volume and respiratory mechanics. Despite high respiratory drive, dyspnoea and respiratory rate are often normal. The underlying mechanism is primarily altered lung perfusion. The anatomical prerequisites for PEEP (positive end-expiratory pressure) to work (lung oedema, atelectasis, and therefore recruitability) are lacking. In the high-dependency unit: the disease starts to worsen either because of its natural evolution or additional patient self-inflicted lung injury (P-SILI). Oedema and atelectasis may develop, increasing recruitability. Noninvasive supports are indicated if they result in a reversal of hypoxaemia and a decreased inspiratory effort. Otherwise, mechanical ventilation should be considered to avert P-SILI. In the intensive care unit: the primary characteristic of the advance of unresolved COVID-19 disease is a progressive shift from oedema or atelectasis to less reversible structural lung alterations to lung fibrosis. These later characteristics are associated with notable impairment of respiratory mechanics, increased arterial carbon dioxide tension (P aCO2 ), decreased recruitability and lack of response to PEEP and prone positioning.


Subject(s)
COVID-19/physiopathology , COVID-19/therapy , Lung/physiopathology , Positive-Pressure Respiration/methods , Respiration, Artificial/methods , Humans , Pulmonary Atelectasis/prevention & control , Respiratory Mechanics , SARS-CoV-2
7.
Intensive Care Med ; 47(10): 1130-1139, 2021 10.
Article in English | MEDLINE | ID: covidwho-1412084

ABSTRACT

PURPOSE: We investigated if the stress applied to the lung during non-invasive respiratory support may contribute to the coronavirus disease 2019 (COVID-19) progression. METHODS: Single-center, prospective, cohort study of 140 consecutive COVID-19 pneumonia patients treated in high-dependency unit with continuous positive airway pressure (n = 131) or non-invasive ventilation (n = 9). We measured quantitative lung computed tomography, esophageal pressure swings and total lung stress. RESULTS: Patients were divided in five subgroups based on their baseline PaO2/FiO2 (day 1): non-CARDS (median PaO2/FiO2 361 mmHg, IQR [323-379]), mild (224 mmHg [211-249]), mild-moderate (173 mmHg [164-185]), moderate-severe (126 mmHg [114-138]) and severe (88 mmHg [86-99], p < 0.001). Each subgroup had similar median lung weight: 1215 g [1083-1294], 1153 [888-1321], 968 [858-1253], 1060 [869-1269], and 1127 [937-1193] (p = 0.37). They also had similar non-aerated tissue fraction: 10.4% [5.9-13.7], 9.6 [7.1-15.8], 9.4 [5.8-16.7], 8.4 [6.7-12.3] and 9.4 [5.9-13.8], respectively (p = 0.85). Treatment failure of CPAP/NIV occurred in 34 patients (24.3%). Only three variables, at day one, distinguished patients with negative outcome: PaO2/FiO2 ratio (OR 0.99 [0.98-0.99], p = 0.02), esophageal pressure swing (OR 1.13 [1.01-1.27], p = 0.032) and total stress (OR 1.17 [1.06-1.31], p = 0.004). When these three variables were evaluated together in a multivariate logistic regression analysis, only the total stress was independently associated with negative outcome (OR 1.16 [1.01-1.33], p = 0.032). CONCLUSIONS: In early COVID-19 pneumonia, hypoxemia is not linked to computed tomography (CT) pathoanatomy, differently from typical ARDS. High lung stress was independently associated with the failure of non-invasive respiratory support.


Subject(s)
COVID-19 , Cohort Studies , Humans , Lung/diagnostic imaging , Prospective Studies , SARS-CoV-2
8.
Crit Care ; 25(1): 264, 2021 07 28.
Article in English | MEDLINE | ID: covidwho-1331951

ABSTRACT

As exemplified by prone positioning, regional variations of lung and chest wall properties provide possibilities for modifying transpulmonary pressures and suggest that clinical interventions related to the judicious application of external pressure may yield benefit. Recent observations made in late-phase patients with severe ARDS caused by COVID-19 (C-ARDS) have revealed unexpected mechanical responses to local chest wall compressions over the sternum and abdomen in the supine position that challenge the clinician's assumptions and conventional bedside approaches to lung protection. These findings appear to open avenues for mechanism-defining research investigation with possible therapeutic implications for all forms and stages of ARDS.


Subject(s)
COVID-19/therapy , Lung Compliance , Prone Position , Humans , Patient Positioning , Pressure , Respiratory Distress Syndrome/virology , Respiratory Mechanics
9.
Crit Care ; 25(1): 250, 2021 07 16.
Article in English | MEDLINE | ID: covidwho-1312651

ABSTRACT

A personalized mechanical ventilation approach for patients with adult respiratory distress syndrome (ARDS) based on lung physiology and morphology, ARDS etiology, lung imaging, and biological phenotypes may improve ventilation practice and outcome. However, additional research is warranted before personalized mechanical ventilation strategies can be applied at the bedside. Ventilatory parameters should be titrated based on close monitoring of targeted physiologic variables and individualized goals. Although low tidal volume (VT) is a standard of care, further individualization of VT may necessitate the evaluation of lung volume reserve (e.g., inspiratory capacity). Low driving pressures provide a target for clinicians to adjust VT and possibly to optimize positive end-expiratory pressure (PEEP), while maintaining plateau pressures below safety thresholds. Esophageal pressure monitoring allows estimation of transpulmonary pressure, but its use requires technical skill and correct physiologic interpretation for clinical application at the bedside. Mechanical power considers ventilatory parameters as a whole in the optimization of ventilation setting, but further studies are necessary to assess its clinical relevance. The identification of recruitability in patients with ARDS is essential to titrate and individualize PEEP. To define gas-exchange targets for individual patients, clinicians should consider issues related to oxygen transport and dead space. In this review, we discuss the rationale for personalized approaches to mechanical ventilation for patients with ARDS, the role of lung imaging, phenotype identification, physiologically based individualized approaches to ventilation, and a future research agenda.


Subject(s)
Precision Medicine/methods , Respiration, Artificial/methods , Respiratory Distress Syndrome/therapy , Humans , Precision Medicine/trends , Respiration, Artificial/trends , Respiratory Distress Syndrome/diagnostic imaging , Respiratory Distress Syndrome/physiopathology , Respiratory Mechanics/physiology
13.
Ann Intensive Care ; 10(1): 88, 2020 Jul 08.
Article in English | MEDLINE | ID: covidwho-635751
14.
Minerva Anestesiol ; 87(3): 325-333, 2021 03.
Article in English | MEDLINE | ID: covidwho-1128285

ABSTRACT

BACKGROUND: In the early stages of COVID-19 pneumonia, hypoxemia has been described in absence of dyspnea ("silent" or "happy" hypoxemia). Our aim was to report its prevalence and outcome in a series of hypoxemic patients upon Emergency Department admission. METHODS: In this retrospective observational cohort study we enrolled a study population consisting of 213 COVID-19 patients with PaO2/FiO2 ratio <300 mmHg at hospital admission. Two groups (silent and dyspneic hypoxemia) were defined. Symptoms, blood gas analysis, chest X-ray (CXR) severity, need for intensive care and outcome were recorded. RESULTS: Silent hypoxemic patients (68-31.9%) compared to the dyspneic hypoxemic patients (145-68.1%) showed greater frequency of extra respiratory symptoms (myalgia, diarrhea and nausea) and lower plasmatic LDH. PaO2/FiO2 ratio was 225±68 mmHg and 192±78 mmHg in silent and dyspneic hypoxemia respectively (P=0.002). Eighteen percent of the patients with PaO2/FiO2 from 50 to 150 mmHg presented silent hypoxemia. Silent and dyspneic hypoxemic patients had similar PaCO2 (34.2±6.8 mmHg vs. 33.5±5.7 mmHg, P=0.47) but different respiratory rates (24.6±5.9 bpm vs. 28.6±11.3 bpm respectively, P=0.002). Even when CXR was severely abnormal, 25% of the population was silent hypoxemic. Twenty-six point five percent and 38.6% of silent and dyspneic patients were admitted to the ICU respectively (P=0.082). Mortality rate was 17.6% and 29.7% (log-rank P=0.083) in silent and dyspneic patients. CONCLUSIONS: Silent hypoxemia is remarkably present in COVID-19. The presence of dyspnea is associated with a more severe clinical condition.


Subject(s)
COVID-19/complications , Hypoxia/epidemiology , Hypoxia/etiology , Aged , Aged, 80 and over , COVID-19/mortality , Cohort Studies , Dyspnea/etiology , Female , Humans , Male , Middle Aged , Prevalence , Retrospective Studies
18.
Intensive Care Med ; 46(12): 2385-2396, 2020 12.
Article in English | MEDLINE | ID: covidwho-917110

ABSTRACT

In ARDS patients, the change from supine to prone position generates a more even distribution of the gas-tissue ratios along the dependent-nondependent axis and a more homogeneous distribution of lung stress and strain. The change to prone position is generally accompanied by a marked improvement in arterial blood gases, which is mainly due to a better overall ventilation/perfusion matching. Improvement in oxygenation and reduction in mortality are the main reasons to implement prone position in patients with ARDS. The main reason explaining a decreased mortality is less overdistension in non-dependent lung regions and less cyclical opening and closing in dependent lung regions. The only absolute contraindication for implementing prone position is an unstable spinal fracture. The maneuver to change from supine to prone and vice versa requires a skilled team of 4-5 caregivers. The most frequent adverse events are pressure sores and facial edema. Recently, the use of prone position has been extended to non-intubated spontaneously breathing patients affected with COVID-19 ARDS. The effects of this intervention on outcomes are still uncertain.


Subject(s)
Prone Position/physiology , Respiratory Distress Syndrome/physiopathology , Respiratory Mechanics/physiology , Humans , Lung Compliance/drug effects , Lung Compliance/physiology , Respiratory Distress Syndrome/complications
19.
Intensive Care Med ; 46(12): 2187-2196, 2020 12.
Article in English | MEDLINE | ID: covidwho-886981

ABSTRACT

PURPOSE: To investigate whether COVID-19-ARDS differs from all-cause ARDS. METHODS: Thirty-two consecutive, mechanically ventilated COVID-19-ARDS patients were compared to two historical ARDS sub-populations 1:1 matched for PaO2/FiO2 or for compliance of the respiratory system. Gas exchange, hemodynamics and respiratory mechanics were recorded at 5 and 15 cmH2O PEEP. CT scan variables were measured at 5 cmH2O PEEP. RESULTS: Anthropometric characteristics were similar in COVID-19-ARDS, PaO2/FiO2-matched-ARDS and Compliance-matched-ARDS. The PaO2/FiO2-matched-ARDS and COVID-19-ARDS populations (both with PaO2/FiO2 106 ± 59 mmHg) had different respiratory system compliances (Crs) (39 ± 11 vs 49.9 ± 15.4 ml/cmH2O, p = 0.03). The Compliance-matched-ARDS and COVID-19-ARDS had similar Crs (50.1 ± 15.7 and 49.9 ± 15.4 ml/cmH2O, respectively) but significantly lower PaO2/FiO2 for the same Crs (160 ± 62 vs 106.5 ± 59.6 mmHg, p < 0.001). The three populations had similar lung weights but COVID-19-ARDS had significantly higher lung gas volume (PaO2/FiO2-matched-ARDS 930 ± 644 ml, COVID-19-ARDS 1670 ± 791 ml and Compliance-matched-ARDS 1301 ± 627 ml, p < 0.05). The venous admixture was significantly related to the non-aerated tissue in PaO2/FiO2-matched-ARDS and Compliance-matched-ARDS (p < 0.001) but unrelated in COVID-19-ARDS (p = 0.75), suggesting that hypoxemia was not only due to the extent of non-aerated tissue. Increasing PEEP from 5 to 15 cmH2O improved oxygenation in all groups. However, while lung mechanics and dead space improved in PaO2/FiO2-matched-ARDS, suggesting recruitment as primary mechanism, they remained unmodified or worsened in COVID-19-ARDS and Compliance-matched-ARDS, suggesting lower recruitment potential and/or blood flow redistribution. CONCLUSIONS: COVID-19-ARDS is a subset of ARDS characterized overall by higher compliance and lung gas volume for a given PaO2/FiO2, at least when considered within the timeframe of our study.


Subject(s)
COVID-19/physiopathology , Respiratory Distress Syndrome/physiopathology , Adult , Aged , Blood Gas Analysis/methods , COVID-19/therapy , Cohort Studies , Female , Humans , Intensive Care Units/organization & administration , Intensive Care Units/statistics & numerical data , Italy , Length of Stay/statistics & numerical data , Lung Compliance/physiology , Male , Middle Aged , Prospective Studies , Pulmonary Gas Exchange/physiology , Respiratory Distress Syndrome/therapy , Simplified Acute Physiology Score , Tomography, X-Ray Computed/methods
20.
Ann Intensive Care ; 10(1): 134, 2020 Oct 12.
Article in English | MEDLINE | ID: covidwho-844004
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