scholarly journals Effects of Body Position and Hypovolemia on the Regional Distribution of Pulmonary Perfusion During One-Lung Ventilation in Endotoxemic Pigs

2021 ◽  
Vol 12 ◽  
Author(s):  
Jakob Wittenstein ◽  
Martin Scharffenberg ◽  
Xi Ran ◽  
Yingying Zhang ◽  
Diana Keller ◽  
...  
Keyword(s):  
Thoracic Surgery ◽  
Supine Position ◽  
Body Position ◽  
Regional Distribution ◽  
Lung Ventilation ◽  
Lateral Position ◽  
Pulmonary Perfusion ◽  
One Lung Ventilation ◽  
Impedance Tomography ◽  
Inflammatory Conditions

Background: The incidence of hypoxemia during one-lung ventilation (OLV) is as high as 10%. It is also partially determined by the distribution of perfusion. During thoracic surgery, different body positions are used, such as the supine, semilateral, lateral, and prone positions, with such positions potentially influencing the distribution of perfusion. Furthermore, hypovolemia can impair hypoxic vasoconstriction. However, the effects of body position and hypovolemia on the distribution of perfusion remain poorly defined. We hypothesized that, during OLV, the relative perfusion of the ventilated lung is higher in the lateral decubitus position and that hypovolemia impairs the redistribution of pulmonary blood flow.Methods: Sixteen juvenile pigs were anesthetized, mechanically ventilated, submitted to a right-sided thoracotomy, and randomly assigned to one of two groups: (1) intravascular normovolemia or (2) intravascular hypovolemia, as achieved by drawing ~25% of the estimated blood volume (n = 8/group). Furthermore, to mimic thoracic surgery inflammatory conditions, Escherichia coli lipopolysaccharide was continuously infused at 0.5 μg kg−1 h−1. Under left-sided OLV conditions, the animals were further randomized to one of the four sequences of supine, left semilateral, left lateral, and prone positioning. Measurements of pulmonary perfusion distribution with fluorescence-marked microspheres, ventilation distribution by electrical impedance tomography, and gas exchange were then performed during two-lung ventilation in a supine position and after 30 min in each position and intravascular volume status during OLV.Results: During one-lung ventilation, the relative perfusion of the ventilated lung was higher in the lateral than the supine position. The relative perfusion of the non-ventilated lung was lower in the lateral than the supine and prone positions and in semilateral compared with the prone position. During OLV, the highest arterial partial pressure of oxygen/inspiratory fraction of oxygen (PaO2/FIO2) was achieved in the lateral position as compared with all the other positions. The distribution of perfusion, ventilation, and oxygenation did not differ significantly between normovolemia and hypovolemia.Conclusions: During one-lung ventilation in endotoxemic pigs, the relative perfusion of the ventilated lung and oxygenation were higher in the lateral than in the supine position and not impaired by hypovolemia.

scholarly journals Effect of Open-Chest Surgery in the Lateral Position on Blood Propofol Concentration during Target-Controlled Infusion of Propofol

2008 ◽  
Vol 36 (6) ◽  
pp. 798-801
Author(s):  
L. H. Tan ◽  
C. J. Cokis ◽  
W. M. Weightman ◽  
A. R. Manopas ◽  
M. J. Paech ◽  
...  
Keyword(s):  
Thoracic Surgery ◽  
Blood Concentration ◽  
Repeated Measures ◽  
Lung Ventilation ◽  
Lateral Position ◽  
One Lung Ventilation ◽  
Open Chest ◽  
Target Controlled Infusion ◽  
Chest Surgery ◽  
Significant Difference

Our research hypothesis was that single lung ventilation during thoracic surgery in the lateral position increases the blood concentration of propofol during target-controlled infusion. Thirty adult patients in two tertiary referral hospitals undergoing open-chest surgery were studied. Anaesthesia was induced and maintained with propofol using a Diprifusor (Graseby 3500) computer-controlled pump set to deliver a blood concentration of 4 μg.ml-1. Blood samples were taken with the patient positioned in 1) the supine position 20 minutes after induction (supine); 2) the lateral position just prior to one-lung ventilation (lateral); 3) the lateral position five minutes after commencing one-lung ventilation (OLV5) and 4) the lateral position 20 minutes after commencing one-lung ventilation (OLV20). Propofol concentrations were determined by high performance liquid chromatography. The target-controlled infusion target level was maintained at 4 μg.ml-1 during the study period for all cases. The mean (SD) propofol blood concentration (μg.ml-1) at each stage was 5.5 (1.5) supine, 5.3 (1.1) lateral, 5.3 (1.2) OLV5 and 5.1 (1.2) OLV20. Repeated measures ANOVA showed an F value 1.9, lambda 5.5 and P value 0.15. Post hoc analysis did not identify a significant difference between the sample times. During target-controlled infusion of propofol, mean blood propofol concentrations did not change significantly from those obtained with the patient supine after up to 50 minutes in the lateral position during thoracic surgery, or 20 minutes after commencing one-lung ventilation.

scholarly journals Helping students to understand physiological aspects of regional distribution of ventilation in humans: a experience from the electrical impedance tomography

2018 ◽  
Vol 42 (4) ◽  
pp. 655-660
Author(s):  
Marcelo Alcantara Holanda ◽  
Nathalia Parente de Sousa ◽  
Luana Torres Melo ◽  
Liégina Silveira Marinho ◽  
Helder Veras Ribeiro-Filho ◽  
...  
Keyword(s):  
Medical Students ◽  
Electrical Impedance ◽  
Respiratory Mechanics ◽  
Pulmonary Ventilation ◽  
Regional Distribution ◽  
Lung Ventilation ◽  
Respiratory Physiology ◽  
Impedance Tomography ◽  
Lateral Decubitus ◽  
Basic Concepts

Undergraduate biomedical students often have difficulties in understanding basic concepts of respiratory physiology, particularly respiratory mechanics. In this study, we report the use of electrical impedance tomography (EIT) to improve and consolidate the knowledge about physiological aspects of normal regional distribution of ventilation in humans. Initially, we assessed the previous knowledge of a group of medical students ( n = 39) about regional differences in lung ventilation. Thereafter, we recorded the regional distribution of ventilation through surface electrodes on a healthy volunteer adopting four different decubitus positions: supine, prone, and right and left lateral. The recordings clearly showed greater pulmonary ventilation in the dependent lung, mainly in the lateral decubitus. Considering the differences in pulmonary ventilation between right and left lateral decubitus, only 33% of students were able to notice it correctly beforehand. This percentage increased to 84 and 100%, respectively ( P < 0.01), after the results of the ventilation measurements obtained with EIT were examined and discussed. A self-assessment questionnaire showed that students considered the practical activity as an important tool to assist in the understanding of the basic concepts of respiratory mechanics. Experimental demonstration of the physiological variations of regional lung ventilation in volunteers by using EIT is feasible, effective, and stimulating for undergraduate medical students. Therefore, this practical activity may help faculty and students to overcome the challenges in the field of respiratory physiology learning.

scholarly journals May awake video-assisted thoracoscopic surgery with thoracic epidural anesthesia use routinely for minimaly invasive thoracic surgery procedures in the future?

2018 ◽  
Vol 5 (5) ◽  
pp. 1602
Author(s):  
Gonul Sagiroglu ◽  
Fazli Yanik ◽  
Yekta A. Karamusfaoglu ◽  
Elif Copuroglu
Keyword(s):  
Thoracic Surgery ◽  
General Anesthesia ◽  
Epidural Anesthesia ◽  
Thoracoscopic Surgery ◽  
Lung Ventilation ◽  
Thoracic Epidural Anesthesia ◽  
One Lung Ventilation ◽  
Thoracic Epidural ◽  
Video Assisted ◽  
Video Assisted Thoracoscopic Surgery

Background: In the last years thoracic surgery developed in greater extent with equipments and techniques in one lung ventilation. Still general anesthesia in one lung ventilation approved as gold standard. In thoracic surgery most performed surgeries are plerural decortication and lung biopsy. Avoidance of intubation in Video Assisted Thoracoscopic Surgery (VATS) procedures gains us some advantages in postoperative period; a better respiratory parameters, survival and morbidity mortality rates, reduced hospitalization time and costs, reduced early stress hormone and immune response.  Methods: In this study, we reported our experience of 24 consecutive patients undergoing VATS with Thoracic Epidural Anesthesia (TEA) between December 2015 through July 2016 to evaluate the feasibility, safety and indication of this innovative technique whether it will be a gold standart in thoracic surgeries or not in the future.Results: Operation procedures included wedge resection in 11 (46%) patients (eight of them for pneumothorax, three of them for diagnosis), in 10 (42%) patients pleural biopsy (eight of them used talc pleurodesis), in two (8%) patients air leak control with fibrin glue and in one (4%) patient bilateral thoracal sympathectomy for hyperhidrosis.  We used T4-5 TEA space for 17 (72%) of patients, while we used T4-6 TEA space for 7 (28%) of patients. TEA block reached the desired level after the mean 26.4±4.3 minutes (range 21-34 min). There was no occurrence of hypotension and bradycardia during and after TEA. One (4%) patient required conversion to general anesthesia and tracheal intubation because of significant diaphragmatic contractions and hyperpne. Conversion to thoracotomy was not needed in any patient.Conclusions: We conclude that nVATS procedure with aid of TEA is feasibile and safety with minimal adverse events. The procedure can have such advantages as early mobilization, opening of early oral intake, early discharge, patient satisfaction, low pain level. Nevertheless, there is a need for randomized controlled trials involving wider case series on the subject.

The impact of body position and exercise on the measurement of liver Young’s modulus by real-time shear wave elastography

2021 ◽  
pp. 1-10
Author(s):  
Xia Jiang ◽  
Li Li ◽  
Hong-Yuan Xue
Keyword(s):  
Healthy Volunteers ◽  
Real Time ◽  
Young’S Modulus ◽  
Shear Wave ◽  
Supine Position ◽  
Young's Modulus ◽  
Body Position ◽  
Shear Wave Elastography ◽  
Lateral Position ◽  
Left Lateral Position

BACKGROUND: In the past ten years, liver biopsies have been used as a method to accurately diagnose the stage of fibrosis. OBJECTIVE: This study aimed to evaluate whether body position and exercise affect the measurement of liver Young’s modulus of healthy volunteers by real-time shear wave elastography (RT-SWE). Methods: RT-SWE was used to measure liver Young’s modulus in the supine and left lateral positions of 70 healthy volunteers at rest and measure the liver Young’s modulus in the lying position before exercise, and at zero, five, and ten minutes of rest after exercise. RESULTS: The liver Young’s modulus in the left lateral position was significantly higher than in the supine position (P< 0.05), and the measured value in the supine position was more stable than the left lateral position. The liver Young’s modulus measured at zero minutes after exercise was significantly higher than that measured before exercise (P< 0.05). The liver Young’s modulus measured at five minutes after exercise was significantly higher than that measured at zero minutes after exercise (P<0.05) and was not statistically different from the measured value before exercise (P> 0.05). The liver Young’s modulus measured at ten minutes after exercise was significantly higher from that measured at zero minutes after exercise (P< 0.05) and was not statistically different from the measured value at five minutes after exercise (P> 0.05). CONCLUSION: Body position and exercise have a significant impact on the measurement of liver Young’s modulus. It is recommended that the examinees take a supine position during the measurement, and measurement should be conducted at least ten minutes after exercise.

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