Ventilation/perfusion distributions revisited

Baumgardner, James E.; Hedenstierna, Göran

doi:10.1097/aco.0000000000000269

Cited by 7 publications

(3 citation statements)

References 41 publications

(29 reference statements)

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“…The induction of general anesthesia itself leads to a decrease in functional residual capacity. If the lung volume drops too low, below the so-called closing capacity, the airways start to close, leading to lung tissue collapse and subsequent atelectasis that causes reduction of the ventilation/perfusion ratio (Va/Q) and intrapulmonary shunt increase (Qs/Qt) (17).…”

Section: Pathophysiology Of Hypoxemia During Olvmentioning

confidence: 99%

One-lung Ventilation for Thoracic Surgery: Current Perspectives

Bernasconi

Piccioni

2017

Tumori

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One-lung ventilation (OLV) is an anesthesiological technique that is increasingly being used beyond thoracic surgery. This requires specific skills and knowledge about airway management, maintenance of gas exchange and prevention of acute lung injury. Sometimes maintaining adequate gas exchange and minimizing acute lung injury may be opposing processes. Parameters validated for OLV titration still have not been found, but a multimodal approach based on low tidal volume, end-expiratory pressure application and alveolar recruitment maneuvers is considered the best way to ensure protective ventilation and reduce lung damage. The purpose of this review is to analyze all these factors using the latest scientific evidence and the opinions of the most influential authors.

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Section: Pathophysiology Of Hypoxemia During Olvmentioning

confidence: 99%

One-lung Ventilation for Thoracic Surgery: Current Perspectives

Bernasconi

Piccioni

2017

Tumori

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“…Other than ventilation in lateral decubitus position, factors that also cause an increase in A-a gradient are acute respiratory distress syndrome (ARDS), pulmonary embolism, right-left cardiac shunts, atelectases, obstructive lung disease, interstitial lung disease [2] and obesity [3].…”

Section: Introductionmentioning

confidence: 99%

Influence of different PEEP levels on electrical impedance tomography findings in patients under general anesthesia ventilated in the lateral decubitus position

Šribar

Merc

Peršec

et al. 2019

J Clin Monit Comput

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To determine the effect of various PEEP levels on electrical impedance tomography (EIT) measured differences in regional ventilation, hemodynamics, lung mechanics and parameters of alveolar gas exchange. Thirty three patients scheduled for elective urologic surgery in general anesthesia in lateral decubitus position were randomized into three groups-PEEP 0, 5 and 10 mbar. EIT recording, arterial blood gas analysis and hemodynamic parameters were captured at three timepointsbefore induction (T0), 5 min after lateral positioning (T1) and 90 min after positioning (T2). Dynamic compliance (Cdyn) was measured at T1 and T2. Offline EIT data analysis was performed to calculate EIT derived parameters of ventilation distribution. Patients ventilated with PEEP of 10 mbar had a significantly lower A-a (alveolo arterial) gradient over measurements and symmetrical distribution of ventilation measured by EIT. There was no significant difference in Cdyn, center of ventilation indices and inhomogeneity index between groups. There was no difference of mean arterial pressure, cardiac index and heart rate between groups. Patients with 5 mbar of PEEP had higher stroke volume index compared to 0 and 10 mbar at baseline and over measurements. Nondependent/dependent TV ratio as well as global inhomogeneity index were correlated with A-a gradient. Dynamic compliance showed no correlation to A-a gradient. In our study, a PEEP level of 10 mbar improved alveolar gas exchange without compromising hemodynamic stability in patients mechanically ventilated in the lateral decubitus position. EIT measured parameters may be used to determine optimal ventilation parameters in these patients with inhomogeneous lung mechanics. Further studies are needed in patients with various lung pathologies.

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“…PaO 2 determines arterial oxygenation, while PaCO 2 (arterial partial pressure of carbon dioxide) indicates carbon dioxide levels dissolved in the arteries (34-38 mmHg under standard conditions). Adequate gas exchange is measured by several factors, including control of ventilation (V), alveolar ventilation (V A ), alveolar-capillary diffusion, and pulmonary perfusion (Q) [4]. The deterioration of any of them or the incorrect coordination between them will determine respiratory failure situations with or without hypercapnia [5].…”

Section: Respiratory Physiologymentioning

confidence: 99%

Oxygen Therapy: Systems and Indications in the Pediatric and Adult Population

García-Muro¹,

Alatorre-Jiménez²,

Johal³

et al. 2020

Iberoam J Med

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Hypoxemia is defined as the decrease in arterial partial pressure of oxygen (PaO2) below 80 mmHg. One of the ways to alleviate this condition is through oxygen therapy, which consists of administering oxygen at a concentration higher than atmospheric. This therapy is indicated in various pathologies and is aimed to treat hypoxemia and reduce the patient's myocardial demand and respiratory effort. Classically, this treatment has been carried out using low-flow systems, in which the inspiratory fraction of oxygen (FiO2) cannot be regulated. However, an increase in the use of high-flow oxygen therapy (HFO) has been observed in recent years. These systems allow for greater patient comfort as well as more precise regulation of the FiO2. The purpose of this article is to review respiratory physiology to understand respiratory failure from a clinical and pathophysiological point of view. Likewise, the different oxygen therapy systems most widely used are discussed, as well as their indications for acute and chronic pathologies, both in the pediatric and adult populations.

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Ventilation/perfusion distributions revisited

Abstract: Methods are continuously developing to simplify measurement of VA/Q and also to relate VA/Q to inflammation. The recording of VA/Q has helped to explain important aspects of gas exchange in thoracic anesthesiology and in intensive care medicine.

Cited by 7 publications

References 41 publications

One-lung Ventilation for Thoracic Surgery: Current Perspectives

One-lung Ventilation for Thoracic Surgery: Current Perspectives

Influence of different PEEP levels on electrical impedance tomography findings in patients under general anesthesia ventilated in the lateral decubitus position

Oxygen Therapy: Systems and Indications in the Pediatric and Adult Population

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