Changes in Speech Breathing Following Cochlear Implant in Postlingually Deafened Adults

Three postlingually deafened adults who received cochlear implants read passages before and after their prostheses were activated while their lung volumes were measured with an Inductive plethysmograph that transduced the cross-sectional areas of the speaker’s chest and abdomen. Lung volumes at the initiation and termination of the speakers’ expiratory limbs, their average air flow, and the volume of air they expended per syllable were derived from tracings of calibrated lung volume displayed by computer. The activation of the speakers’ cochlear prostheses was followed in every case by a significant change in average airflow, which rose for two subjects with initially low flow rates and fell for one subject who had a much higher average preimplant flow rate. These changes in average flow rate were accompanied by corresponding changes in volume of air expended per syllable, statistically reliable in two of the three cases. There were no significant changes in the levels at which speakers initiated their expiratory limbs, but one speaker, after his prosthesis was activated, reliably increased the level of air in his lungs at the end of expiratory limbs to an average value that no longer required him to draw on expiratory reserve volume.

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Maximal Expiratory Flow and Lung Volume Changes Associated with Exercise-Induced Asthma in Children and the Effect of Breathing a Low-Density Gas Mixture

Clinical Science ◽

10.1042/cs0460317 ◽

1974 ◽

Vol 46 (3) ◽

pp. 317-329 ◽

Cited By ~ 2

Author(s):

S. R. Benatar ◽

P. König

Keyword(s):

Flow Rate ◽

Vital Capacity ◽

Forced Expiratory Volume ◽

Cross Sectional Area ◽

Sectional Area ◽

Cross Sectional ◽

Lung Volumes ◽

Flow Rates ◽

Before And After ◽

Expiratory Flow

1. Lung volumes and maximum expiratory flow volume (MEFV) curves were measured before and after exercise and after a bronchodilator in eight asthmatic children. 2. Exercise produced significant changes in all volumes and flow rates measured, but the most sensitive measurement was of flow rate at an absolute volume in the terminal portion of the forced vital capacity. Of the more simply obtained measurements maximal flow at 50% of the exhaled vital capacity was the most sensitive, but reductions in forced expiratory volume at 1 s and peak flow rate were almost as marked. 3. The marked reductions in flow rates at low lung volumes after exercise were accompanied by large increases in residual volume and a reduction in the slope of the MEFV curve. These changes suggest functional closure of some lung units and an increase in the time-constant of emptying of other units. 4. The response of flow to breathing helium—oxygen (79:21, v/v) was assessed in the dilated state (before exercise or after bronchodilator) and the constricted state (after exercise) in five of the subjects. 5. An increase in density-dependence of flow rates at all lung volumes during constriction is evidence that, despite the reduction in flow rates, convective acceleration and turbulent flow constitute a greater proportion of the total upstream resistance after exercise than before exercise. The implication is that the cross-sectional area at equal pressure points (EPP) is smaller after exercise than before exercise. This could result from either bronchoconstriction with no change in the location of EPP, or from progression of the EPP further upstream to a region where loss of airways or reduction in their diameter has rendered the total cross-sectional area considerably smaller than under normal circumstances.

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Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽

10.1159/000514460 ◽

2021 ◽

pp. 1-5

Author(s):

Jingjing Liu ◽

Tengfang Chen ◽

Zhenggang Lv ◽

Dezhong Wu

Keyword(s):

Flow Rate ◽

Oxygen Therapy ◽

Preliminary Investigation ◽

Nasal Cannula ◽

Low Flow ◽

Antiplatelet Drugs ◽

Flow Rates ◽

The Past ◽

Oxygen Inhalation ◽

Significant Difference

Introduction: In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. Methods: We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. Results: No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ2 = 1.007, p > 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ2 = 2.082, p > 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate <5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ2 = 0.838, p > 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ2 = 18.428, p < 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ2 = 26.194, p < 0.001). Discussion/Conclusion: Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

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Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2016-0078 ◽

2019 ◽

Vol 36 (4) ◽

pp. 401-410 ◽

Cited By ~ 2

Author(s):

Xiao-Qi Jia ◽

Bao-Ling Cui ◽

Zu-Chao Zhu ◽

Yu-Liang Zhang

Keyword(s):

Centrifugal Pump ◽

Flow Rate ◽

Pressure Fluctuation ◽

Pressure Fluctuations ◽

High Flow ◽

Low Flow ◽

Centrifugal Pumps ◽

Flow Rates ◽

Pressure Distributions ◽

Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

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Malondialdehyde Levels in Preeclampsia before and after Delivery

Indonesian Journal of Obstetrics and Gynecology ◽

10.32771/inajog.v6i3.777 ◽

1970 ◽

pp. 143

Author(s):

Harold Rumopa ◽

Freddy W. Wagey ◽

Eddy Suparman

Keyword(s):

Oxidative Stress ◽

Plasma Levels ◽

Cross Sectional Study ◽

Hplc Method ◽

Wilcoxon Test ◽

Sectional Study ◽

Cross Sectional ◽

Average Value ◽

Significant Difference ◽

Before And After

Objective: Determine differences plasma levels MDA in preeclampsiabefore and 2 hours after delivery. Methods: This was an analytic cross-sectional study. Subjectconsists of 23 pregnancies with preeclampsia, where 23 bloodsamples taken before delivery and 23 were taken 2 hours afterdelivery. This study was conducted from August 2016 untilDecember 2016 at Department of Obstetrics and GynecologyFaculty of Medicine Universitas Sam Ratulangi / Prof. Dr. R. D.Kandou Hospital Manado and satellite hospital. Samples weretaken from plasma and analysed using HPLC method at Prodiaclinical laboratory. Results: In patients with severe preeclampsia before deliverywe found average value (1.4796  0.40819 nmol/ml), minimumvalue (1.03 nmol/ml) and maximal value (2.77 nmol/ml)and 2 hours after delivery with average value (1.2470 0.34324 nmol/ml), minimum value (0.91 nmol/ml), and maximumvalue (2.47 nmol/ml). by using Wilcoxon test, we foundthere were significant differences in plasma levels of MDA (p =0.000). Conclusion: This significant difference suggests that decreasedplasma levels of MDA 2 hours after delivery and gives the sense thatthere is a relationship between oxidative stress of cells with severepreeclampsia before and shortly after delivery, that MDA is an indicatorof oxidative stress. Keywords: malondialdehyde, oxidative stress, peroxidation lipid,preeclampsia

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Effects of short blades on performance and inner flow characteristics of a low-specific-speed centrifugal pump

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650917695672 ◽

2017 ◽

Vol 231 (4) ◽

pp. 290-302 ◽

Cited By ~ 4

Author(s):

Can Kang ◽

Ning Mao ◽

Chen Pan ◽

Yang Zhu ◽

Bing Li

Keyword(s):

Centrifugal Pump ◽

Flow Rate ◽

Pressure Fluctuations ◽

Flow Characteristics ◽

Low Flow ◽

Back Surface ◽

Flow Rates ◽

Pump Operation ◽

Low Specific Speed ◽

Specific Speed

A low-specific-speed centrifugal pump equipped with long and short blades is studied. Emphasis is placed on the pump performance and inner flow characteristics at low flow rates. Each short blade is intentionally shifted towards the back surface of the neighboring long blade, and the outlet parts of the short blades are uniformly shortened. Unsteady numerical simulation is conducted to disclose inner flow patterns associated with the modified design. Thereby, a comparison is enabled between the two schemes featured by different short blades. Both practical operation data and numerical results support that the deviation and cutting of the short blades can eliminate the positive slope of pump head curve at low flow rates. Therefore, the modification of short blades improves the pump operation stability. Due to the shortening of the outlet parts of the short blades, velocity distributions between impeller outlet and radial diffuser inlet exhibit explicitly altered circumferential flow periodicity. Pressure fluctuations in the radial diffuser are complex in terms of diversified periodicity and amplitudes. Flow rate influences pressure fluctuations in the radial diffuser considerably. As flow rate decreases, the regularity of the orbit of hydraulic loads exerted upon the impeller collapses while hydraulic loads exerted upon the short blades remain circumferentially periodic.

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Cerebral Hyperperfusion Syndrome by the Numbers: Transient Focal Neurological Deficit, Imaging-Proven Focal Hyperperfusion, and High Graft Flow Rate Following Superficial Temporal Artery-Middle Cerebral Artery bypass in a Patient With Symptomatic Carotid Occlusion—Case Report

Operative Neurosurgery ◽

10.1093/ons/opy010 ◽

2018 ◽

Vol 15 (6) ◽

pp. E94-E99 ◽

Cited By ~ 3

Author(s):

Ralph Rahme ◽

Tejaswi D Sudhakar ◽

Marjan Alimi ◽

Timothy G White ◽

Rafael A Ortiz ◽

...

Keyword(s):

Middle Cerebral Artery ◽

Flow Rate ◽

Perfusion Imaging ◽

Superficial Temporal Artery ◽

Temporal Artery ◽

Low Flow ◽

Flow Rates ◽

Cerebral Hyperperfusion Syndrome ◽

Cerebral Hyperperfusion ◽

Graft Flow

Abstract BACKGROUND AND IMPORTANCE Cerebral hyperperfusion syndrome (CHS) is a well-known complication of superficial temporal artery (STA) to middle cerebral artery (MCA) bypass for ischemic cerebrovascular disease. While this argues against “low flow” in the bypass construct, flow rates in the graft have not been previously quantified in the setting of CHS. CLINICAL PRESENTATION A 58-yr-old man presented with recurrent left hemispheric ischemic strokes and fluctuating right hemiparesis and aphasia. Vascular imaging revealed left cervical internal carotid artery occlusion and perfusion imaging confirmed left hemispheric hypoperfusion. After failing to respond to maximal medical therapy, the patient underwent single-barrel STA-MCA bypass. Postoperatively, his symptoms resolved and blood pressure (BP) was strictly controlled within normal range. However, 2 d later, he developed severe expressive aphasia. CTA demonstrated a patent bypass graft and SPECT showed focal hyperperfusion in Broca's speech area. Seizure activity was ruled out. A high graft flow rate of 52 mL/min was documented by quantitative magnetic resonance angiography (MRA). Thus, the diagnosis of CHS was made and managed with strict BP control. The patient exhibited complete recovery of speech over a period of days and was discharged home. Repeat SPECT at 4 mo showed resolution of hyperperfusion and quantitative MRA demonstrated reduction of graft flow rate to 34 mL/min. CONCLUSION This is the first case of perfusion imaging-proven CHS after STA-MCA bypass, where high graft flow rates are objectively documented. Our observations constitute irrefutable evidence challenging the classic belief that the STA-MCA bypass is a low-flow construct.

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Interaction between CO2 concentration and flow rate on peripheral airway resistance

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.6.2514 ◽

1991 ◽

Vol 70 (6) ◽

pp. 2514-2521 ◽

Cited By ~ 3

Author(s):

A. Kaise ◽

A. N. Freed ◽

W. Mitzner

Keyword(s):

Flow Rate ◽

Airway Resistance ◽

Co2 Concentration ◽

Low Flow ◽

Flow Rates ◽

Peripheral Airway ◽

Residual Capacity ◽

Local Ventilation ◽

End Tidal ◽

The Relationship

In the present study, we investigated the interaction between CO2 concentration and rate of delivered flow on peripheral airway resistance (Rp) in the intact canine lung. Dogs were anesthetized, intubated, paralyzed, and mechanically ventilated with room air to maintain end-tidal CO2 between 4.8 and 5.2%. Using a wedged bronchoscope technique, we measured Rp at functional residual capacity. The relationship between CO2 concentration and Rp was measured at flow rates of 100 and 400 ml/min with 5, 3, 2, 1, and 0% CO2 in air. Measurements were made at the end of a 3-min exposure to each gas. At low flow rates (100 ml/min) responses to hypocapnia were small, whereas at high flow rates (400 ml/min) responses were large. The PC50 (defined as the CO2 concentration required to produce a 50% increase in Rp above baseline Rp established on 5% CO2) at 400 ml/min (1.73%) was significantly larger than that at 100 ml/min (0.38%). We also directly measured the relationship between Rp and flow rate with 5% CO2 (normocapnia) or 1% CO2 (hypocapnia) delivered into the wedged segment. Increases in normocapnic flow caused small but significant decreases in Rp. In contrast, increases in hypocapnic flow from 100 to 400 ml/min caused a 108% increase in Rp. Thus the response to hypocapnia is augmented by increasing flow rate. This interaction can be explained by a simple model that considers the effect of local ventilation-perfusion ratio and gas mixing on the local CO2 concentration at the site of peripheral airway contraction.

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The Influence of Flow Rate on the Wake in a Centrifugal Impeller

Volume 1: Turbomachinery ◽

10.1115/82-gt-45 ◽

1982 ◽

Author(s):

M. W. Johnson ◽

J. Moore

Keyword(s):

Flow Rate ◽

Incidence Angle ◽

Three Dimensional ◽

Stagnation Pressure ◽

Centrifugal Impeller ◽

Suction Surface ◽

Cross Sectional ◽

Flow Rates ◽

Pressure Losses ◽

Compressor Impeller

Three-dimensional flows and their influence on the stagnation pressure losses in a centrifugal compressor impeller have been studied. All 3 mutally perpendicular components of relative velocity and stagnation pressure on 5 cross-sectional planes, between the inlet and outlet of a 1 m dia shrouded impeller running at 500 rpm were measured. Comparisons were made between results for a flow rate corresponding to nearly zero incidence angle and two other flows, with increased and reduced flow rates. These detailed measurements show how the position of separation of the shroud boundary layer moved downstream and the wake’s size decreased, as the flow rate was increased. The wake’s location, at the outlet of the impeller, was also observed to move from the suction surface at the lowest flow rate, to the shroud at higher flow rates.

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Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

Volume 1: Turbomachinery ◽

10.1115/91-gt-070 ◽

1991 ◽

Author(s):

Ronald D. Flack ◽

Steven M. Miner ◽

Ronald J. Beaudoin

Keyword(s):

Centrifugal Pump ◽

Reynolds Stress ◽

Flow Rate ◽

Cross Product ◽

Design Flow ◽

Low Flow ◽

Rate Variation ◽

Flow Rates ◽

The Individual ◽

Design Flow Rate

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two directional laser velocimeter. Data presented includes radial, tangential, and cross product Reynolds stresses. Blade to blade profiles were measured at four circumferential positions and four radii within and one radius outside the four bladed impeller. The pump was tested in two configurations; with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (ε/r2 = 0.016). Flow rates ranged from 40% to 106% of the design flow rate. Variation in profiles among the individual passages in the orbiting impeller were found. For several regions the turbulence was isotropic so that the cross product Reynolds stress was low. At low flow rates the highest cross product Reynolds stress was near the exit. At near design conditions the lowest cross product stress was near the exit, where uniform flow was also observed. Also, near the exit of the impeller the highest turbulence levels were seen near the tongue. For the design flow rate, inlet turbulence intensities were typically 9% and exit turbulence intensities were 6%. For 40% flow capacity the values increased to 18% and 19%, respectively. Large local turbulence intensities correlated with separated regions. The synchronous orbit did not increase the random turbulence, but did affect the turbulence in the individual channels in a systematic pattern.

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Suppression of Self-Excited Flow Instability in a Radial Diffuser Using Rough Surfaces

Volume 2: Fora ◽

10.1115/fedsm2006-98261 ◽

2006 ◽

Author(s):

Saad A. Ahemd ◽

Hayder Salem

Keyword(s):

Flow Rate ◽

Smooth Surface ◽

Flow Instability ◽

Rough Surfaces ◽

Flow Coefficient ◽

Flow Instabilities ◽

Low Flow ◽

Flow Rates ◽

Flow Limit ◽

Stable Operating

Flow instabilities in a compression system at low flow rates set the flow limit of the stable operating range. Experiments to investigate the feasibility of controlling the stall in the radial diffuser of a low speed centrifugal compressor were carried out. The technique was very simple and involved using rough surfaces (i.e., sand papers) attached to the diffuser shroud. The results showed that the flow instability in the diffuser (stall) was delayed to a lower flow coefficient (the mass flow rate could be reduced to 70% of its value with the smooth surface) when the rough surfaces were positioned on the diffuser shroud.

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