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Ventilation-perfusion mismatch

Blandine Truffault, Philippe Robin, Cecile Tromeur, Alexandra Le Duc Pennec, Ronan Abgral, David Bourhis, Francis Couturaud, Gregoire Le Gal, Pierre-Yves Salaun, Pierre-Yves Le Roux
OBJECTIVE: Following the implementation of single-photon emission computed tomography ventilation/perfusion (SPECT V/Q) in our department, we previously carried out an observational study over the period 2011-2013 that showed the safety of SPECT V/Q to rule out pulmonary embolism (PE). However, PE prevalence (28%) was high compared with some studies. Our hypothesis was that the use of SPECT V/Q may be responsible for an overdiagnosis of PE, especially at the implementation phase of the test...
February 7, 2019: Nuclear Medicine Communications
Gurumurthy Hiremath, Athar M Qureshi, Lourdes R Prieto, Lakshmi Nagaraju, Phillip Moore, Lisa Bergersen, Nathaniel W Taggart, Jeffery Meadows
OBJECTIVES: This study sought to determine whether pulmonary artery intervention in patients with unilateral proximal pulmonary artery stenosis (PAS) improves exercise capacity, abnormal ventilatory response to exercise, and symptoms. BACKGROUND: Stenosis of the branch pulmonary arteries results in pulmonary blood flow maldistribution (PBFM). The resulting ventilation-perfusion mismatch is associated with an increased ventilatory response to exercise and decreased exercise capacity...
February 11, 2019: JACC. Cardiovascular Interventions
Antonia Koutsoukou, Matteo Pecchiari
Expiratory flow limitation (EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. Recent evidence suggests that the presence of EFL is associated with an increase in mortality, at least in acute respiratory distress syndrome (ARDS) patients, and in pulmonary complications in patients undergoing surgery. EFL is a major cause of intrinsic positive end-expiratory pressure (PEEPi), which in ARDS patients is heterogeneously distributed, with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation...
January 23, 2019: World Journal of Critical Care Medicine
Eilon Ram, Leonid Sternik, Robert Klempfner, Michael Eldar, Ilan Goldenberg, Yael Peled, Ehud Raanani, Alexander Kogan
OBJECTIVES: The phosphodiesterase-5 inhibitor sildenafil was developed for the treatment of pulmonary hypertension. The authors investigated the efficacy and safety of sildenafil in the early postoperative period after mitral valve surgery in patients with pulmonary hypertension. DESIGN: A double-blind, placebo-controlled randomized trial was performed. SETTING: The trial was performed in a single tertiary referral center. PARTICIPANTS: Fifty consecutive patients who experienced pulmonary hypertension and underwent mitral valve surgery...
December 25, 2018: Journal of Cardiothoracic and Vascular Anesthesia
Marika Bajc, Ari Lindqvist
Ventilation/perfusion single-photon emission computed tomography (V/P SPECT) is the scintigraphic technique recommended primarily for the diagnosis of acute pulmonary embolism (PE) and is golden standard for the diagnosis of chronic PE. Furthermore, interpreting ventilation and corresponding perfusion images enables pattern recognition of many other cardiopulmonary disorders that affect lung function and also allows quantification of their extent. Using Technegas for the ventilation imaging, grading of small airway disease in COPD is possible and the method is recommended for PE diagnosis in patients with severe COPD that is not possible with radiolabelled liquid aerosols...
January 2019: Seminars in Nuclear Medicine
Alejandro Sanchez-Crespo
Single photon emission computed tomography (SPECT) provides high contrast three dimensional images of the regional distribution of a radiotracer. SPECT is a widely used technique in pulmonary investigations of the ventilation (V) and perfusion (Q) in the adult patient, mainly in the diagnosis of pulmonary embolism. However, safety concerns among practitioners due to radiation exposure and the use of macroaggregate albumin for the perfusion scan have historically precluded the use of SPECT in pediatric patients with nonembolic pulmonary disorders...
January 2019: Seminars in Nuclear Medicine
Ben Korman, Ranjan K Dash, Philip J Peyton
The second gas effect (SGE) occurs when nitrous oxide enhances the uptake of volatile anesthetics administered simultaneously. Recent work shows that the SGE is greater in blood than in the gas phase, that this is due to ventilation-perfusion mismatch, that as mismatch increases, the SGE increases in blood but is diminished in the gas phase, and that these effects persist well into the period of nitrous oxide maintenance anesthesia. These modifications of the SGE are most pronounced with the low soluble agents in current use...
December 6, 2018: Journal of Applied Physiology
Nobuaki Hamazaki, Takashi Masuda, Kentaro Kamiya, Ryota Matsuzawa, Kohei Nozaki, Emi Maekawa, Chiharu Noda, Minako Yamaoka-Tojo, Junya Ako
BACKGROUND AND OBJECTIVE: Respiratory muscle weakness causes fatigue in these muscles during exercise and thereby increases dead-space ventilation ratio with decreased tidal volume. However, it remains unclear whether respiratory muscle weakness aggravates ventilation-perfusion mismatch through the increased dead-space ventilation ratio. In ventilation-perfusion mismatch during exercise, minute ventilation versus carbon dioxide production (VE/VCO2 ) slope > 34 is an indicator of poor prognosis in patients with chronic heart failure (CHF)...
February 2019: Respirology: Official Journal of the Asian Pacific Society of Respirology
Nathan Marzlin, Sara Dunbar, Michael Cinquegrani
INTRODUCTION: Platypnea-orthodeoxia syndrome is a rare clinical syndrome defined by worsening deoxygenation and dyspnea when changing to an upright sitting or standing position. It is seen in 3 different clinical scenarios: intracardiac shunts, pulmonary arteriovenous shunts, and ventilation/perfusion mismatch in the lungs. CASE: An 82-year-old woman with a history of nonischemic cardiomyopathy with reduced ejection fraction was admitted with dyspnea and hypoxemia...
October 2018: WMJ: Official Publication of the State Medical Society of Wisconsin
Andrew W Bowman, Brittany K Albers, Manoj K Jain
Despite the increasing use of computed tomography pulmonary angiography to evaluate for pulmonary embolism (PE), ventilation/perfusion (V/Q) scintigraphy is still a fairly common examination. A rare finding on V/Q scintigraphy is whole-lung mismatched perfusion defect. Although this finding can occur with PE, it has an important, limited differential diagnosis. In this pictorial essay, we describe different causes of acquired whole-lung mismatched perfusion defect.
October 2018: Indian Journal of Nuclear Medicine: IJNM: the Official Journal of the Society of Nuclear Medicine, India
Julien Dupont, Didier Serteyn, Charlotte Sandersen
Horses are susceptible to developing large areas of pulmonary atelectasis during recumbency and anesthesia. The subsequent pulmonary shunt is responsible for significant impairment of oxygenation. Since ventilation perfusion mismatch persists into the post-operative period, hypoxemia remains an important concern in the recovery stall. This case report describes the diagnosis and supportive therapy of persistent hypoxemia in a 914 kg draft horse after isoflurane anesthesia. It highlights how challenging it can be to deal with hypoxemia after disconnection from the anesthesia machine and how life-threatening it can become if refractory to treatment...
2018: Frontiers in Veterinary Science
Morgan Hepburn-Brown, Jai Darvall, Gary Hammerschlag
An acute pulmonary embolism (aPE) is characterised by occlusion of one or more pulmonary arteries. Physiological disturbance may be minimal, but often cardiac output decreases as the right ventricle attempts to overcome increased afterload. Additionally, ventilation-perfusion mismatches can develop in affected vascular beds, reducing systemic oxygenation. Incidence is reported at 50-75 per 100 000 in Australia and New Zealand, with 30-day mortality rates ranging from 0.5% to over 20%. Incidence is likely to increase with the ageing population, increased survival of patients with comorbidities that are considered risk factors and improving sensitivity of imaging techniques...
January 2019: Internal Medicine Journal
Vijay Kumar Mishra, Souvik Chaudhuri, Rajesh Kumar Singh, Ajay Kumar Singh
Unilateral pulmonary artery agenesis (UPAA) is a rare condition where the patient may remain asymptomatic for a long period till adulthood. Presentation may be in the form of dyspnea, cough, hemoptysis, decreased exercise tolerance, and recurrent respiratory tract infections. Ventilation-perfusion mismatch and excessive blood flow to the normal lung may eventually lead to unilateral acute respiratory distress syndrome (ARDS). We present a case of a 40-year-old gentleman with nonresolving pneumonia who was diagnosed to have unilateral ARDS due to UPAA...
July 2018: Anesthesia, Essays and Researches
Robert Ruemmler, Alexander Ziebart, Christian Moellmann, Andreas Garcia-Bardon, Jens Kamuf, Frances Kuropka, Bastian Duenges, Erik Kristoffer Hartmann
BACKGROUND: The effects of different ventilation strategies during CPR on patient outcomes and lung physiology are still poorly understood. This study compares positive pressure ventilation (IPPV) to passive oxygenation (CPAP) and a novel ultra-low tidal volume ventilation (ULTVV) regimen in an experimental ventricular fibrillation animal model. STUDY DESIGN: Prospective randomized controlled trial. ANIMALS: 30 male German landrace pigs (16-20 weeks)...
November 2018: Resuscitation
Sethuraman Swaminathan, Arpit Agarwal, Juan C Infante, Eliot Rosenkranz
Tetralogy of Fallot with absent pulmonary valve syndrome is a rare form of congenital heart disease. Among the different variations with this rare anomaly is nonconfluent pulmonary artery branches with anomalous origin of the left pulmonary artery from the ductus arteriosus. The authors present one such case which was diagnosed prenatally to have tetralogy of Fallot with absent pulmonary valve and identified postnatally to have nonconfluent pulmonary artery branches in addition. We discuss the conundrum of respiratory management in this patient pre- and postoperatively due to a unique ventilation perfusion mismatch problem, which varies between the two lungs...
August 27, 2018: World Journal for Pediatric & Congenital Heart Surgery
Henrik Reinius, Joao Batista Borges, Joakim Engström, Oskar Ahlgren, Fredrik Lennmyr, Anders Larsson, Filip Fredén
BACKGROUND: One-lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions. METHODS: Right-sided OLV with capnothorax (16 cm H2 O) on the left side was initiated in eight anesthetized, muscle-relaxed piglets. A recruitment maneuver and a decremental PEEP titration from PEEP 20 cm H2 O to zero end-expiratory pressure (ZEEP) was performed...
August 21, 2018: Acta Anaesthesiologica Scandinavica
Sam Orde, Michel Slama, Nicola Stanley, Stephen Huang, Anthony Mclean
BACKGROUND: Transthoracic 3D cardiac analysis is enticing in its potential simplicity and wealth of data available. It has been suggested to be accurate vs magnetic resonance imaging in relatively stable patients, but feasibility and agreement with conventional echocardiographic assessment of stroke volume (SV) have not been thoroughly assessed in critically ill patients, who are traditionally harder to image. The objectives of this study were to compare 3D transthoracic volumetric analysis vs Doppler assessment of SV (which is suggested to be accurate in the critically ill) and Simpson's biplane assessment in a cohort typical of the intensive care unit (ICU), where accurate assessment is important: mechanically ventilated patients with a significant ventilation/perfusion (V/Q) mismatch...
August 19, 2018: Critical Care: the Official Journal of the Critical Care Forum
Alastair J E Moore, Jason Wachsmann, Murthy R Chamarthy, Lloyd Panjikaran, Yuki Tanabe, Prabhakar Rajiah
Imaging plays an important role in the evaluation and management of acute pulmonary embolism (PE). Computed tomography (CT) pulmonary angiography (CTPA) is the current standard of care and provides accurate diagnosis with rapid turnaround time. CT also provides information on other potential causes of acute chest pain. With dual-energy CT, lung perfusion abnormalities can also be detected and quantified. Chest radiograph has limited utility, occasionally showing findings of PE or infarction, but is useful in evaluating other potential causes of chest pain...
June 2018: Cardiovascular Diagnosis and Therapy
Ebru Biricik, Feride Karacaer, Yasemin Güneş, Nebile Dağlıoğlu, Pınar Efeoğlu, Murat Ilgınel, Alper Avcı, Dilek Özcengiz
OBJECTIVE: To determine the blood sevoflurane and desflurane concentrations during one-lung ventilation (OLV). DESIGN: Randomized, single-blind study. SETTING: Single university hospital. PARTICIPANTS: The study comprised 24 patients, 35 to 70 years old who were scheduled for either a major abdominal surgery or thoracotomy. INTERVENTIONS: The patients were divided into the following 4 groups: sevoflurane two-lung ventilation (TLV), sevoflurane OLV, desflurane TLV, and desflurane OLV...
June 1, 2018: Journal of Cardiothoracic and Vascular Anesthesia
D Chemla, E Berthelot, P Assayag, P Attal, P Hervé
The right ventricle (RV) plays a key role in the maintenance of an adequate cardiac output whatever the demand, and thus contributes to the optimization of the ventilation/perfusion ratio. The RV has a thin wall and it buffers the physiological increases in systemic venous return without causing a deleterious rise in right atrial pressure (RAP). The RV is coupled to the pulmonary circulation which is a low pressure, low resistance, high compliance system. In the healthy subject at rest, the contribution of the RV to right heart systolic function is surpassed by the contribution of both left ventricular contraction and the respiratory pump...
December 2018: Revue des Maladies Respiratoires
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