Pulmonary Embolism and Gas Exchange

Fernandes, Caio; Assad, Ana Paula Luppino; Alves-Jr, Jose Leonidas; Jardim, Carlos; Souza, Rogério

doi:10.1159/000501342

Cited by 32 publications

(16 citation statements)

References 44 publications

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“…This is quite different from chronic exposure where acclimatization plays an important role and also from gradually occurring mild hypoxia. Sudden hypoxemia can also occur in illnesses as acute pulmonary embolism (Fernandes et al, 2019 ). Another situation is apneic hypoxia, which is associated with several specific responses (Schagatay, 2009 ) but differs from eupneic hypoxia as it implies the cessation of normal respiration.…”

Section: Introductionmentioning

confidence: 99%

Spleen Contraction During Sudden Eupneic Hypoxia Elevates Hemoglobin Concentration

Pernett

Schagatay²,

Vildevi³

et al. 2021

Front. Physiol.

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The spleen contracts progressively during moderate normobaric hypoxia exposure of 20 min, which elevates hemoglobin concentration (Hb). However, acute hypoxia exposure could be shorter and more severe when oxygen systems fail during, e.g., high-altitude sky diving, aircraft cabin pressure drop, balloon flights, extreme altitude climbing, and in some maladies. We aimed to evaluate the speed and magnitude of spleen contraction during short exposure to extreme eupneic hypoxia and its subsequent recovery on oxygen. Eight female and seven male volunteers were exposed to normobaric hypoxia (10% oxygen) for 10 min during sitting rest, followed by 10 min on 100% oxygen. Heart rate (HR), arterial oxygen saturation (SpO2), and mean arterial blood pressure (MAP) were measured continuously. The spleen was measured via ultrasonic imaging every minute for volume calculations, and venous blood samples were drawn before and after exposure for hemoglobin concentration (Hb). Mean (SD) spleen volume was 279 (115) mL before exposure, 219 (75) mL (21% reduction; P = 0.005) at 3 min of exposure, and 201 (93) mL after 10 min exposure to hypoxia (28% reduction; P < 0.001). Hb was 138.8 (7.6) g·L−1 before and 142.9 (8.1) g·L−1 after 10 min of exposure (2.9% increase; P < 0.001). SpO2 was 96.4 (1.7)% before exposure and 74.7 (8.4)% during the last minute of exposure (22.5% reduction; P < 0.001). HR increased from 80 (14) to 90 (17) bpm during exposure (12% increase, P < 0.05). MAP remained unchanged. After 10 min recovery on oxygen, values had been restored for spleen volume and Hb, while SpO2 was higher and HR lower compared with before hypoxia exposure. We concluded that acute normobaric hypoxia of only 10 min caused significant spleen volume contraction with Hb increase. This rapid spleen response, evident already after 3 min of exposure, could have a protective effect during sudden exposure to severe hypoxia.

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Section: Introductionmentioning

confidence: 99%

Spleen Contraction During Sudden Eupneic Hypoxia Elevates Hemoglobin Concentration

Pernett

Schagatay²,

Vildevi³

et al. 2021

Front. Physiol.

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show abstract

“…Furthermore, from a dose-response relationship between arterial oxygen levels and outcomes, severe hyperoxia was more consistently associated with poor outcomes (hospital and ICU mortality) than mild hyperoxia [9]. On the other side, the hypoxaemia could be induced by APE, which contributes to the increase in pulmonary artery pressure and in severe cases it aggravates the hemodynamic impairment [40]. Thus, optimal oxygen targets are required to minimize and balance the competing risks of hypoxaemia and hyperoxaemia in APE patients.…”

Section: Discussionmentioning

confidence: 99%

Admission Oxygen Saturation and Mortality in Acute Pulmonary Embolism Patients: Observational Data From Large ICU Databases

Peng

Shen

et al. 2021

Preprint

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Background The relationship between blood oxygenation and clinical outcomes of acute pulmonary embolism (APE) patients in intensive care unit (ICU) is unclear, which could be nonlinear. The study aimed to determine the association between admission pulse oximetry-derived oxygen saturation (SpO2) levels and mortality, and to determine the optimal range with real-world data. Methods Patients diagnosed with APE on admission and staying in ICU for at least 24 hours in the Medical Information Mart for Intensive Care III (MIMIC-III) database and the eICU Collaborative Research Database (eICU-CRD) were included. Logistic regression and restricted cubic spline (RCS) models were applied to determine the nonlinear relationship between mean SpO2 levels within the first 24 hours after ICU admission and in-hospital mortality, from which we derived an optimal range of SpO2. Subgroup analyses were based on demographics, treatment information, scoring system and comorbidities. Results We included 1109 patients who fulfilled inclusion criteria, among whom 129 (12%) died during hospitalization and 80 (7.2%) died in ICU. The RCS showed that the relationship between admission SpO2 levels and in-hospital mortality of APE patients was nonlinear and U-shaped. The optimal range of SpO2 with the lowest mortality was 95–98%. Multivariate stepwise logistic regression analysis with backward elimination confirmed that the admission SpO2 levels of 95%-98% was associated with decreased hospital mortality compared to the group with SpO2 < 95% (Odds ratio [OR] = 2.321; 95% confidence interval [CI]: 1.405–3.786; P < 0.001) and 100% (OR = 2.853; 95% CI: 1.294–5.936; P = 0.007), but there was no significant difference compared with 99% SpO2 (OR = 0.670, 95% CI: 0.326–1.287; P > 0.05). This association was consistent across subgroup analyses. Conclusions The relationship between admission SpO2 levels and in-hospital mortality followed a U-shaped curve among patients with APE. The optimal range of SpO2 for APE patients was 95–98%.

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“…Bronchial constriction out of pathological segments has been known from decades for pulmonary embolism [28,29,30]. In a pulmonary embolism, bronchoconstriction is mediated by hypocapnia induced by hyperpnea and tachypnea that can also be observed in SARS-CoV-2 pneumonia.…”

Section: Discussionmentioning

confidence: 99%

Microvascular Injury With Secondary Edema, Bronchoconstriction and Vasoconstriction of Non-involved Lung Parenchymal Segments May Contribute to Clinical Deterioration of Non-critically Ill Patients Hospitalized for SARS-CoV-2 Pneumonia Without Evidence of Pulmonary Embolism: A Preliminary Study.

Maincent

Perrin

Chironi

et al. 2021

Preprint

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Purpose: We aimed to better understand the pathophysiology of SARS-CoV-2 pneumonia in non-critically ill hospitalized patients secondarily presenting with clinical deterioration and increase in oxygen requirement.Methods: We consecutively enrolled patients without clinical or biological evidence for superinfection, without left ventricular (LV) dysfunction and for whom a pulmonary embolism was discarded by computed tomography pulmonary angiography. We investigated lung ventilation and perfusion (LVP) by LVP scintigraphy, and, 24 hours later, left and right ventricular function by 99mTc-labelled albumin gated-blood-pool scintigraphy with late (60 mn) tomographic albumin images on the lungs to evaluate lung albumin retention that could indicate microvascular injuries with secondary edema. Results: We included 13 patients with confirmed SARS-CoV-2 pneumonia. All had CT evidence of organizing pneumonia and normal LV ejection fraction.No patient demonstrated preserved ventilation with perfusion defect (mismatch), which may eliminate a distal lung thrombosis. Patterns of ventilation and perfusion were heterogeneous with sometimes healthy lung segments paradoxically hypoperfused and hypoventilated while both normal perfusion and ventilation were maintained in segments with organizing pneumonia (n=4). Lung albumin retention in area of organizing pneumonia was observed in 9 patients, indicating microvascular injuries, vessel permeability increase and secondary edema.Conclusion: In hospitalized non-critically ill patients without pulmonary embolism or LV dysfunction, various types of damage may contribute to clinical deterioration including microvascular injuries and secondary edema, broncho and vasoconstriction of area not involved by organizing pneumonia while no evidence was found for significant distal thrombosis detectable by LVP scintigraphy.

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Pulmonary Embolism and Gas Exchange

Cited by 32 publications

References 44 publications

Spleen Contraction During Sudden Eupneic Hypoxia Elevates Hemoglobin Concentration

Spleen Contraction During Sudden Eupneic Hypoxia Elevates Hemoglobin Concentration

Admission Oxygen Saturation and Mortality in Acute Pulmonary Embolism Patients: Observational Data From Large ICU Databases

Microvascular Injury With Secondary Edema, Bronchoconstriction and Vasoconstriction of Non-involved Lung Parenchymal Segments May Contribute to Clinical Deterioration of Non-critically Ill Patients Hospitalized for SARS-CoV-2 Pneumonia Without Evidence of Pulmonary Embolism: A Preliminary Study.

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