OBJECTIVE: To determine a relation between acute inner ear pressure changes and cochlear function as measured by low-level 2f(1)-f(2) distortion product otoacoustic emissions (DPOAEs). MATERIAL AND METHODS: During and after a change in inner ear pressure induced by injection or aspiration of perilymph, the 2f(1)-f(2) DPOAE at 4.5 kHz generated ...

BACKGROUND: The aim of the study was to compare sealing characteristics of the new Microcuff pediatric tracheal tube featuring a high volume-low pressure (HVLP) cuff with ultrathin membrane with three conventional pediatric cuffed tracheal tubes. METHODS: After obtaining approval of the local ethical committee, 80 children aged 2-4 years were ...

AIM: To investigate the diagnostic value of ultrasonography in mild and moderate idiopathic carpal tunnel syndrome (CTS). MATERIALS AND METHODS: Cross-sectional areas (CSA), flattening ratios at three different levels, swelling ratio, and palmar displacement were analysed in 26 patients (14 with bilateral and 12 with unilateral disease, 40 wrists in ...

Narghile (water-pipe) smoking requires the generation of significant negative intrapharyngeal pressure, which may be transmitted to the middle ear through the Eustachian tube. A total of 80 ears from regular narghile smokers were examined otoscopically and by tympanometry. Seventy ears from heavy cigarette smokers were similarly examined and served as ...

PURPOSE: We compare the Soft Seal and Unique single-use, plastic laryngeal mask airway devices with respect to intracuff pressure, directly measured mucosal pressure and in vitro elastance. METHODS: Ten fresh male cadavers were studied. Microchip pressure sensors were attached to the following locations: A) the anterior middle part of the ...

The study was designed to investigate the changes in pressure and volume of a tracheal tube-cuff inflated with air, mixture of N2O + O2, saline and 4% lidocaine during nitrous oxide anesthesia. This study was conducted in 80 patients (33 male & 47 female). The pressure and volume of a ...

BACKGROUND: The aim of this study was to investigate cuff compliance and cuff pressure during nitrous oxide exposure in the recently introduced Microcuff tracheal tube with a polyurethane cuff (Microcuff GmbH, Weinheim, Germany), and to compare it to conventional tracheal tubes with PVC cuffs. METHODS: In an in vitro set ...

Reported here is a technique for measuring forward and reverse middle-ear transmission that exploits distortion-product otoacoustic emissions (DPOAEs) to drive the middle ear "in reverse" without opening the inner ear. The technique allows measurement of DPOAEs, middle-ear input impedance, and forward and reverse middle-ear transfer functions in the same animal. ...

Excitatory amino acid (EAA) transmission in the rostral portion of the ventrolateral medulla (RVLM) appears to be required for reflex airway constriction. The purpose of the present study was to determine whether our prior observations of right sided dominance are also reflected at the level of the RVLM, particularly at ...

The electromyogram (EMG) and intramuscular pressure (IMP) increase linearly with force during voluntary static contractions, while the surface mechanomyogram (MMG) increases linearly only up to approximately 70% of the maximal voluntary contraction (MVC) and then levels off. The aim of this study was to investigate the possible influence of IMP ...

A facial nerve palsy, as a result of middle-ear high pressure, is a rare complication of sub-aqua diving. It may occur as a result of an acute pressure change in the middle ear during ascent in those patients who have experienced difficulty equalizing their middle-ear pressure during the prior descent. ...

HYPOTHESIS: Both a normal and a narrowed eustachian tube (ET) are capable of equilibrating pressures between the middle ear (ME) and the atmosphere almost instantaneously. OBJECTIVES: The objective of this study was to assess experimentally the effect of narrowing a simulated ET isthmus on air passage into the ME. METHODS: ...

We have examined the stability of double wall carbon nanotubes under hydrostatic pressures up to 10 GPa. The tangential optical phonon mode observed by inelastic light scattering is sensitive to the in-plane stress and splits into a contribution associated with the external and internal tube. While the pressure coefficient from ...

Cardiac looping is a vital morphogenetic process that transforms the initially straight heart tube into a curved tube normally directed toward the right side of the embryo. While recent work has brought major advances in our understanding of the genetic and molecular pathways involved in looping, the biophysical mechanisms that ...

STUDY OBJECTIVES: To study endotracheal tube (ETT) cuff pressures during nitrous oxide (N2O) anesthesia when the cuffs are inflated with air to achieve sealing pressure, and to evaluate the frequency of postoperative laryngotracheal complaints. DESIGN: Prospective, randomized, blind study. SETTING: Metropolitan teaching hospital. PATIENTS: 50 ASA physical status I and ...

Benign paroxysmal positional vertigo (BPPV) is a mechanical disorder of the vestibular system in which calcite particles called otoconia interfere with the mechanical functioning of the fluid-filled semicircular canals normally used to sense rotation. Using hydrodynamic models, we examine the two mechanisms proposed by the medical community for BPPV: cupulolithiasis, ...

OBJECTIVE: The cochlear aqueduct connects the scala tympani to the subarachnoid space and is the main pressure equalization canal for the inner ear. Increases in inner ear volume and pressure are thought to cause clinical symptoms such as vertigo, tinnitus and fluctuating hearing loss. In this study the flow resistance ...

BACKGROUND: Tracheal mucosal damage related to tracheal intubation has been widely described in pediatric and adult patients. High volume-low pressure cuffs (HVLPC) are being advertised as safe to avoid this particularly unpleasant complication. Compliances of these supposed pediatric and adult HVLPC are not mentioned by manufacturers and still remain unknown. ...

Infantile tracheomalacia is a potentially life-threatening disease requiring prolonged artificial respiratory support. Diagnosis and management of this disease may be further improved by establishing a suitable objective and quantitative assessment protocol for tracheal collapsibility. It is our hypothesis that tracheal collapsibility can be represented by the relationship between intraluminal pressure ...

OBJECTIVE: To describe the local hemodynamics and pressure losses of crural bypass anastomoses using instantaneous velocity fields acquired by particle image velocimetry (PIV). METHODS: Silastic models of a Taylor patch, a Miller cuff and a femoro-crural patch prosthesis (FCPP) were attached to a circuit driven by a Berlin Heart, providing ...

OBJECTIVE: The objective of this study was to investigate the effect on experimental endolymphatic hydrops in guinea pigs after hyperbaric therapy. BACKGROUND: The histopathologic character of Ménière's disease is the presence of endolymphatic hydrops. Endolymphatic hypertension could be one of the factors resulting from endolymphatic hydrops. Some treatments of Ménière's ...

The major symptoms of glomus tympanicum tumors are pulsatile tinnitus and spontaneous impedance changes (SICs) of the middle ear. On the other hand, SICs often occur even in the absence of pathological findings. The aim of this study was to analyze the occurrence of SICs in patients and healthy volunteers. ...

Central venous catheters are widely used as a hemoaccess method for dialysis therapy. In this study, the performance parameters (velocities, pressure drop, shear rates, access recirculation) of the Niagara catheter are analyzed using computational fluid dynamics. Side holes are left open, closed, or reduced in size to assess the influence ...

Continuous flow positive pressure devices bridge the gap between mechanical and unsupported ventilation in patients recovering from critical illness. At this point, patients are often fully awake, yet the inflated tracheostomy cuff prevents them from speaking or swallowing. The aim of this study was to investigate the effects of cuff ...

BACKGROUND AND OBJECTIVE: There are concerns over the intra-cuff pressure of the laryngeal mask and laryngopharyngeal morbidity. In a randomized study, the authors compared cuff-pressure changes in the LMA-Classic and the new disposable Soft Seal laryngeal mask during nitrous oxide anaesthesia. METHODS: Two-hundred adult patients were randomly assigned to a ...

BACKGROUND AND AIMS: The formation of a gastric tube is associated with partial devascularisation of the stomach and impaired tissue perfusion in the anastomotic region. The aim of the study was to gain data on the time interval of microcirculatory recovery of the normal gastric conduit. PATIENTS AND METHODS: Twenty-nine ...

The Laryngeal tube (VBM Medizintechnik, Sulz, Germany), a new supraglottic airway, consists of an airway tube, two cuffs, and two distal apertures between the two cuffs. One concern with the use of this device is ischemic change to the oropharyngeal mucosa. We studied the time-course change of the intracuff pressure ...

During and after microinjection of artificial endolymph into scala media of the guinea pig, the 2f1- f2 -DPOAE at 4.5 kHz generated by low-level primaries was recorded. Reproducible changes were measured when 1.1 microl of artificial endolymph was injected at a rate of 1.65 nl/s (1.53-1.83). This volume corresponds with ...

BACKGROUND AND OBJECTIVE: To compare the recently introduced Microcuff endotracheal tube with conventional tubes in respect of the cuff pressures required to prevent air leakage. METHODS: The following tubes (ID 7.0mm) were compared: Microcuff HVLP ICU, Mallinckrodt HiLo, Portex Profile Soft Seal, Rüsch Super Safety Clear and Sheridan CF. Fifty ...

PURPOSE: To evaluate, in a laboratory setting, the accuracy and the clinical use of focal tube constriction as a means to regulate intraocular pressure after glaucoma drainage implant surgery. MATERIALS AND METHODS: A silicone tube identical to the one used in the Baerveldt and other glaucoma drainage implants was connected ...

Changes in the inner ear due to increased intracranial pressure have not yet been clearly defined. We present a postmortem temporal bone study of child with hydrocephalus. The temporal bone was from a 2-year-old female with IVth ventricle ependymoblastoma. In the basal turn of the cochlea, degeneration of the organ ...

Cosmetic disfigurement is a common result of facial burn injuries. Next to judicious wound care and timely wound closure, the application of pressure to maturing facial scars is a key factor in minimizing disfigurement. This is not true for ear burns, where pressure is contraindicated at all phases of recovery, ...

OBJECTIVES: To compare the physical characteristics of ureteral access sheaths that affect their ability to resist buckling and kinking in the ureter. METHODS: Eight commercially available ureteral sheaths were tested. The buckling pressure was measured by adding sequential loads to a point 20 cm from the tip of the sheath ...

Although the endolymphatic sac (ES) is thought to be a primary site for endolymph volume regulation, we have limited knowledge of how it responds to volume and pressure changes. In a prior publication, we demonstrated changes of K(+), Na(+) and endolymphatic sac potential (ESP) resulting from volume injections into, and ...

OBJECTIVE: The total pressure in the middle ear depends on the air composition of this gas pocket, i.e. on gas exchanges occurring through either the Eustachian tube (ET) or mucosa. The aim of this study was to develop an experimental model to investigate the exclusive role of trans-mucosal gas exchanges ...

Barotrauma is pressure-induced injury. The application of direct pressure to the body may cause trauma, including positive pressure from artificial ventilation. Trauma may also be caused by the effects of pressure changes on gas-containing body spaces, not in communication with the environment. This can include the external ear, the middle ...

OBJECTIVE: This paper aims to highlight the physical principles of pressure and flow dynamics underlying endotracheal suctioning, to demonstrate these on a simple illustrative model and to discuss the clinical implications of these principles for paediatric practice. DESIGN: Prospective in vitro study. SETTING: Paediatric intensive care unit of a tertiary, ...

We demonstrate that when a single-walled carbon nanotube is under pressure it undergoes a series of shape transitions, first transforming from a circle to an oval and then from an oval to a peanut. Most remarkably, the ratio of the area of the tube cross sections at the second transition ...

BACKGROUND: We sought to determine the benefits of using alkalinized lidocaine 40 mg to fill the cuff of a tracheal tube (ETT) in combination with water-soluble gel lubrication to prevent post-intubation sore throat. METHODS: The work included an in vitro study of the diffusion of alkalinized lidocaine solution through the ...

Aeromedical transport of mechanically ventilated critically ill patients is now a frequent occurrence. However, the performance of the air filled tracheal tube cuff at altitude has not been studied in vivo. We measured the tracheal cuff pressures at ground level and at 3000 ft, in 10 intubated patients. With air ...

INTRODUCTION: The most common cause of barotitis is pressure changes induced during descent in aviation. The incidence after air flight has been reported to vary from 8% to 17%. OBJECTIVES: We conducted this study to estimate the incidence of barotitis after flight, to evaluate whether the incidence of barotitis can ...

BACKGROUND: The Ipas double-valve manual vacuum aspiration (MVA) syringe is an alternative to electrical vacuum aspiration. METHODS: This study determines which US cannulae (flexible, rigid-straight and rigid-curved) work with the Ipas MVA syringe. Cannulae from Ipas, MedGyn, Berkeley and Milex, in sizes 6-12 mm, were randomized and affixed to the ...

In order to determine whether adhesion of the subacromial bursa leads to impingement, we measured the subacromial contact pressures before and after release of adhesion of this bursa. 18 shoulders with cuff tears and adhesion of the subacromial bursa were evaluated in 8 male and 10 female patients, of mean ...

INTRODUCTION: Routine measurement of endotracheal tube (ETT) cuff pressure is a standard in respiratory care, and several devices are available for measuring ETT cuff pressure. Yet an informed choice in the buying process is hindered by the present paucity of unbiased, comparative data. METHODS: Four brands of cuff inflator were ...

BACKGROUND: Cuff pressure in endotracheal (ET) tubes should be in the range of 20-30 cm H2O. We tested the hypothesis that the tube cuff is inadequately inflated when manometers are not used. METHODS: With IRB approval, we studied 93 patients under general anesthesia with an ET tube in place in ...

The growth rate and albumin concentration of interstitial fluid cuffs were measured in isolated rabbit lungs inflated with albumin solution (3 g/dl) to constant airway (Paw) and vascular pressures for up to 10 h. Cuff size was measured from images of frozen lung sections, and cuff albumin concentration (Cc) was ...

OBJECTIVE: To investigate the motion of the normal and reconstructed ossicular chain during changes in static pressure. MATERIAL AND METHODS: Experiments were carried out using seven fresh human temporal bones Using digital photography, movements of the malleus were measured during incremental pressure changes between +500 and -500 daPa with the ...

Although circulatory impairment of the cochlea would be intuitively a possible cause of sudden sensorineural hearing loss (SSHL), definite proof is lacking. A 46-year-old man developed bilateral SSHL immediately after rapid reduction of the blood pressure in malignant hypertension. Vertigo and left-sided hearing impairment and tinnitus resolved spontaneously a few ...

BACKGROUND: The goal of this investigation was to evaluate adequacy of the design of readily available paediatric cuffed tracheal tubes (CPTT). METHODS: In 15 series of cuffed (11) and uncuffed (four) paediatric tracheal tubes (ID: 2.5-7.0 mm) from four different manufacturers the following dimensions were measured: outer diameter of the ...

Broadband noise absorption, including low frequencies, may be obtained by a hybrid passive-active two-layer system. A porous layer in front of an air layer provides passive absorption, at medium and high frequencies. Active control of the input impedance of the two-layer system yields absorption at low frequencies. The active control ...