Magnetic induction pneumography: a planar coil system for continuous monitoring of lung function via contactless measurements

Abstract Continuous monitoring of lung function is of particular interest to the mechanically ventilated patients during critical care. Recent studies have shown that magnetic induction measurements with single coils provide signals which are correlated with the lung dynamics and this idea is extended here by using a 5 by 5 planar coil matrix for data acquisition in order to image the regional thoracic conductivity changes. The coil matrix can easily be mounted onto the patient bed, and thus, the problems faced in methods that use contacting sensors can readily be eliminated and the patient comfort can be improved. In the proposed technique, the data are acquired by successively exciting each coil in order to induce an eddy-current density within the dorsal tissues and measuring the corresponding response magnetic field strength by the remaining coils. The recorded set of data is then used to reconstruct the internal conductivity distribution by means of algorithms that minimize the residual norm between the estimated and measured data. To investigate the feasibility of the technique, the sensitivity maps and the point spread functions at different locations and depths were studied. To simulate a realistic scenario, a chest model was generated by segmenting the tissue boundaries from NMR images. The reconstructions of the ventilation distribution and the development of an edematous lung injury were presented. The imaging artifacts caused by either the incorrect positioning of the patient or the expansion of the chest wall due to breathing were illustrated by simulations.

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Immediate Effects on Lung Function of Instilled Human Surfactant in Mechanically Ventilated Newborn Infants with IRDS

Acta Paediatrica ◽

10.1111/j.1651-2227.1990.tb11550.x ◽

1990 ◽

Vol 79 (8-9) ◽

pp. 750-755 ◽

Cited By ~ 39

Author(s):

K. E. EDBERG ◽

B. EKSTRÖM-JODAL ◽

M. HALLMAN ◽

O. HJALMARSON ◽

K. SANDBERG ◽

...

Keyword(s):

Lung Function ◽

Newborn Infants ◽

Mechanically Ventilated

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Interfacility Ventilator Management

Acute Care Casebook ◽

10.1093/med/9780190865412.003.0015 ◽

2018 ◽

pp. 67-71

Author(s):

Christopher Galton

Keyword(s):

Health Care ◽

Differential Diagnosis ◽

Neuromuscular Blockade ◽

Patient Comfort ◽

Critically Ill Patient ◽

Mechanically Ventilated ◽

Iatrogenic Complications ◽

Ventilator Management ◽

Adequate Sedation ◽

Ventilator Synchrony

Treating persistent hypoxia while attempting to transport a patient from one health care setting to a destination facility can be one of the most stressful situations emergency medical services providers face. In some cases, the primarily pathology may not be well defined. This case reviews the approach to managing a critically ill patient who is mechanically ventilated and is being transferred to a quaternary center for continued management. The case works through a differential diagnosis of hypoxemia in a mechanically ventilated patient. It also includes dynamic adjustments of the ventilator to maximize success and reduce any potential iatrogenic complications. Finally, adequate sedation is pivotal to promote ventilator synchrony and patient comfort. This case illustrates the nuances of sedation and when neuromuscular blockade should be considered.

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Effects of Intrathoracic Pressure Regulation on Lung Function and Mechanics in Hypovolemic Mechanically Ventilated Pigs - An Explorative Trial

10.1164/ajrccm-conference.2020.201.1_meetingabstracts.a5257 ◽

2020 ◽

Author(s):

M. Scharffenberg ◽

J.J.M. Wittenstein ◽

X. Ran ◽

S. Tauer ◽

R. Theilen ◽

...

Keyword(s):

Lung Function ◽

Intrathoracic Pressure ◽

Pressure Regulation ◽

Mechanically Ventilated ◽

Intrathoracic Pressure Regulation

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Prolonged methacholine-induced bronchoconstriction in dogs

Journal of Applied Physiology ◽

10.1152/jappl.1979.47.2.418 ◽

1979 ◽

Vol 47 (2) ◽

pp. 418-424 ◽

Cited By ~ 5

Author(s):

J. W. Ramsdell ◽

P. F. Georghiou

Keyword(s):

Lung Function ◽

Gas Exchange ◽

Lung Compliance ◽

Cholinergic Stimulation ◽

Partial Pressure Of Oxygen ◽

Pulmonary Resistance ◽

Mechanically Ventilated ◽

Arterial Partial Pressure ◽

Dynamic Lung Compliance ◽

And Control

We studied the effect of prolonged airways obstruction induced by extended cholinergic stimulation in five anesthetized, mechanically ventilated dogs. A continuous intravenous metacholine infusion was utilized to maintain pulmonary resistance (RL) at 200--1500% preinfusion levels for 13--23 h. At maximum RL (18.86 +/- 7.74 vs. 2.09 +/- 0.18 (mean +/- SD) cmH2O/ (L/S) PREINfusion; P less than 0.01), dynamic lung compliance (Cdyn) fell from 67.5 +/- 14.6 to 32.7 +/- 11.6 ml/cmH2O (P less than 0.005) and arterial partial pressure of oxygen (PaO2) fell modestly from 95.8 +/- 6.1 Torr preinfusion to 83.2 +/- 12.7 Torr (P less than 0.05). Tachyphylaxis to methacholine developed, requiring increases in infusion rates to maintain elevated RL. Abnormalities in lung function resolved promptly upon termination of the infusion. Two similarly instrumented control animals ventilated for 19 and 25 h without metacholine infusion had no change in RL, Cdyn, or PaO2. Histological examination of the lungs revealed no differences between infused and control animals. In spite of marked increases in RL, prolonged cholinergic stimulation produced only mild changes in gas exchange and no sustained changes in lung function or structure.

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Management of sedation in the critically ill

10.1093/med/9780199600830.003.0359 ◽

2016 ◽

Author(s):

Bhakti K. Patel ◽

John P. Kress

Keyword(s):

Intensive Care Unit ◽

Patient Comfort ◽

Moving Target ◽

Ventilator Associated Pneumonia ◽

Mechanically Ventilated ◽

Mechanically Ventilated Patients ◽

Icu Length Of Stay ◽

Prolonged Sedation ◽

Frequent Assessment ◽

Ventilated Patients

Once adequate analgesia is confirmed, the need for sedation should be considered. Sedation of mechanically-ventilated patients is a common challenge in the intensive care unit (ICU). Metabolism of sedatives in critical illness can be unpredictable and achieving optimal sedation without coma is a moving target. Once adequate analgesia is achieved, the choice, depth, and duration of sedation can have major implications for the presence of delirium, the duration of mechanical ventilation, ventilator-associated pneumonia, and ICU length of stay. Therefore, goal-directed titration of sedative and frequent assessment of the depth of sedation is important to strike the delicate balance of patient comfort, while avoiding excessive prolonged sedation.

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Pre- versus post-ventilatory surfactant treatment in surfactant-deficient preterm lambs

Reproduction Fertility and Development ◽

10.1071/rd9951333 ◽

1995 ◽

Vol 7 (5) ◽

pp. 1333 ◽

Cited By ~ 10

Author(s):

JJ Cummings ◽

BA Holm ◽

PA Nickerson ◽

WH Ferguson ◽

EA Egan

Keyword(s):

Lung Function ◽

Lung Surfactant ◽

Efficiency Index ◽

Mechanically Ventilated ◽

Hyaline Membrane ◽

Surfactant Administration ◽

Lung Liquid ◽

To Receive ◽

Uniform Deposition ◽

Over Time

Twenty lambs at 127 days' gestation (term is 145 days) were randomly assigned to receive Infasurf (Calf Lung Surfactant Extract, ONY Inc., Amherst, NY) as an intratracheal bolus (3 mliter kg-1) either into a fluid-filled lung before ventilation (n = 10), or after ventilation for 5 min (n = 10). All lambs were surfactant-deficient by analysis of lung liquid obtained before surfactant administration. Lambs were then mechanically ventilated for 4 h. Oxygenation for the lambs given surfactant before ventilation did not change during the experiment; a/A pO2 was 0.50 +/- 0.13 at 1 h and 0.52 +/- 0.17 at 4 h. For the lambs given surfactant after initial ventilation, oxygenation decreased over time; a/A pO2 decreased from 0.48 +/- 0.23 at 1 h to 0.37 +/- 0.22 at 4 h (P < 0.05). Compliance, as calculated from the Ventilator Efficiency Index (VEI), improved over time in both groups, but was always significantly higher for lambs given surfactant before ventilation (P = 0.03). Histologic examination of the lungs revealed no differences between the groups; no evidence of epithelial denudation or hyaline membrane formation was seen in either group. Thus, ventilation of surfactant-deficient newborn lambs for 5 min before surfactant administration results in significantly decreased lung function when compared with surfactant administration before ventilation. These differences in lung function are not dependent on a histopathologic injury to the lung. It is possible that unevenness of deposition of the surfactant in an air-filled lung, compared to more uniform deposition in a fluid-filled unventilated lung, produces these differences.

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