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Results 801 - 850 of 1429
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Meijburg H W - - 1994
During mechanical ventilation with high levels of positive end-expiratory pressure (PEEP) several hemodynamic changes occur, the mechanism of which has been the subject of various previous studies. The effects of increasing levels of PEEP during mechanical ventilation were measured on left atrial and left ventricular filling dynamics, as assessed by ...
Ryan P T - - 1994
This study compared the physiologic responses to forward and retrograde simulated stair stepping on the StairMaster 4000 PT. Twenty male subjects (mean age 23.65 +/- 1.63 years) volunteered for this study. Subjects completed a practice trial of 6 minutes of both forward and retrograde stepping at Level 5. Each experimental ...
Huemer G - - 1994
The advent of modern Doppler two-dimensional ultrasound technology has overcome the need of invasive measurements of several important cardiac parameters. It allows estimation of preload, contractility, and afterload. Positive end-expiratory pressure (PEEP) is associated with a reduction in cardiac output. The responsible mechanisms are controversial. To evaluate the cardiovascular responses ...
Konyukov Y - - 1994
Work of breathing necessary to trigger a ventilator (WOBtr) was calculated during pressure support ventilation (PSV), and the effect of bias flow on WOBtr was evaluated. A spring-loaded bellows type lung model with two bellows placed in series was used to simulate spontaneous breathing. A Venturi mechanism of jet flow ...
Schuster D P - - 1994
PURPOSE: To determine whether positive end-expiratory pressure (PEEP) would change the altered regional pulmonary perfusion pattern caused by oleic acid (OA)-induced acute lung injury was the aim of this study. Our hypothesis was that fixed intravascular obstruction would not be affected by PEEP, leaving the perfusion pattern unchanged if this ...
Mancebo J - - 1994
Volume-controlled ventilation with positive end-expiratory pressure (PEEP) (CPPV) is the conventional ventilatory approach in adult respiratory distress syndrome (ARDS) patients, but some reports suggest that pressure-controlled ventilation with an inverse inspiratory to expiratory ratio (PCIRV) may improve gas exchange in these patients. We analysed the acute effects on gas exchange, ...
Fletcher R - - 1994
Increased end-expiratory pressure (EEP) is usually associated with expiratory obstruction. By pressing the "expiratory pause hold" button on the Servo ventilator 900C, EEP was measured at four stages during coronary bypass surgery: before sternotomy (I), after sternotomy with the sternal edges fully retracted (II), after completed extracorporeal circulation, sternal edges ...
Hernandez P - - 1994
Dynamic measurements of intrinsic positive end-expiratory pressure (PEEPi,dyn) considerably underestimate values obtained under static conditions (PEEPi,stat) in patients with severe airway obstruction. This may be related to regional differences in respiratory system mechanical properties and/or viscoelastic behavior. To evaluate this concept, PEEPi,stat and PEEPi,dyn were compared in six anesthetized paralyzed ...
Fedullo A J - - 1994
It has been stated that positive pressure ventilation (PPV) may cause false positive impedance plethysmography (IPG) results because PPV can decrease venous outflow. We studied 36 patients who were being weaned from mechanical ventilation to determine the effect of PPV on IPG. Patients had IPGs performed during spontaneous ventilation and ...
Poggi R - - 1994
Application of positive and expiratory pressure (PEEP) is widely used in mechanically ventilated patients with acute respiratory failure (ARF) due to adult respiratory distress syndrome. Recent studies have suggested that application of PEEP can be useful in patients with chronic obstructive pulmonary disease (COPD) to reduce the mechanical inspiratory load ...
Matsumoto S - - 1994
To define the difference between the responses of slowly adapting pulmonary stretch receptors (SARs) to reduced dynamic lung compliance (Cdyn) and to administered histamine, experiments were performed in open-chest, artificially ventilated, bilaterally vagotomized rabbits with positive end-expiratory pressure (PEEP). Both stimuli caused an increase in tracheal pressure and produced augmentation ...
Lessard M R - - 1994
BACKGROUND: Pressure-controlled (PCV) and pressure-controlled inverse ratio ventilation (PCIRV) have been proposed instead of volume-controlled conventional ratio ventilation (VC) with positive end-expiratory pressure (PEEP) for patients with adult respiratory distress syndrome (ARDS). The advantages advocated with the use of PCIRV are to decrease airway pressures and to improve gas exchange. ...
Berglund J E - - 1994
OBJECTIVE: This study was designed to see if humorally mediated negative inotropism contributes to the cardiac output (CO) depression seen during positive end-expiratory pressure (PEEP) ventilation. DESIGN: 8 pairs of piglets were used and a combined blood circulation was established between the two animals in each pair. One animal was ...
Bartholomew K M - - 1994
It is well recognised that reducing positive end expiratory pressure (PEEP) leads to an increase in the tidal volume and minute volume in ventilated neonates. The magnitude of this effect is perhaps not commonly appreciated, however. Effectively, PEEP is four times as potent as peak inflation pressure (PIP) in bringing ...
Shanholtz C - - 1994
IRV-induced increases in MAP are clearly associated with shunt reduction, but we find no studies that show shunt reduction without increased end-expiratory alveolar pressure. On the other hand, various studies in humans with ARDS and hyaline membrane disease and animal models of acute lung injury indicate that shunt reduction does ...
Appendini L - - 1994
To assess physiologic effects of continuous positive airway pressure (CPAP) and positive end-expiratory pressure (PEEP) during noninvasive pressure support ventilation (PSV) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), we measured in seven patients the breathing pattern, lung mechanics, diaphragmatic effort (PTPdi), and arterial blood gases under ...
Rossi A - - 1994
Recent work in patients with acute respiratory failure (ARF) due to exacerbation of chronic airflow obstruction (CAO) suggests that application of low degrees of positive end-expiratory pressure (PEEP) can improve rather than impair respiratory mechanics, because PEEP replaces intrinsic PEEP (PEEPi). However, the impact of PEEP on pulmonary gas exchange ...
Muscedere J G - - 1994
Intermittent positive pressure ventilation with large tidal volumes and high peak airway pressures can result in pulmonary barotrauma. In the present study, we examined the hypothesis that ventilation at very low lung volumes can also worsen lung injury by repeated opening and closing of airway and alveolar duct units as ...
King L G - - 1994
Intermittent positive-pressure ventilation (PPV) is an invasive means of respiratory support that is indicated in animals with central and peripheral neuromuscular disease, as well as in those with primary disorders of the lung parenchyma. We reviewed the medical records of 34 dogs and 7 cats treated with PPV. The animals ...
Hedenstierna G - - 1994
BACKGROUND: Atelectasis formation during anesthesia may be due to loss of respiratory muscle tone, in particular that of the diaphragm. This was tested by tensing the diaphragm by phrenic nerve stimulation (PNS) and observing the effect on atelectasis. METHODS: Twelve patients (mean age 48 yr) without preexisting lung disease were ...
Terndrup T E - - 1994
STUDY OBJECTIVE: Impaired cardiac and respiratory responses during active tonic-clonic convulsions (ictal periods) may contribute to complications during seizures. This study characterized physiologic parameters in two pentylenetetrazol (PTZ)-induced seizure models. PARTICIPANTS: Twelve spontaneously breathing piglets. INTERVENTIONS: Under ketamine anesthesia, a tracheostomy was performed, and an arterial catheter and epidural electrodes ...
Ducharme N G - - 1994
Repeatability of measurements of peak and mean tracheal and pharyngeal pressures in exercising horses was determined. Five athletically fit horses were subjected to repeated (n = 5) standardized exercise trials. Static pressures in the trachea, nasopharynx, and mask were determined. At least 96% of all mean pressure measurements were within ...
Easa D - - 1994
Recent reports have suggested that substituting continuous negative extrathoracic pressure (CNEP) for positive end-expiratory pressure (PEEP) may result in clinical benefits to infants with pulmonary disease. Other studies have suggested potential hemodynamic advantages. We compared the effects of CNEP and PEEP in 13 mechanically ventilated newborn piglets after acute lung ...
Cohendy R - - 1994
The respiratory resistive properties of the normal human respiratory system are volume-dependent. The overall flow resistance (Rmax,rs) can be partitioned into airway resistance (Raw) and the additional resistance (delta Rrs) which may result from the viscoelastic properties of the respiratory system, from inequality of time constants (pendelluft), or from both. ...
Veddeng O J - - 1994
Differential ventilation with selective positive end-expiratory pressure (PEEP) has been shown to reduce cardiac output less than general PEEP. In previous studies we have demonstrated that during selective PEEP left ventricular preload is better maintained than during general PEEP. The present study was designed to determine whether the different haemodynamic ...
Dechman G - - 1994
We studied the changes in dynamic elastance and resistance of the respiratory system in 6 supine, anaesthetized, paralysed, tracheostomised and open chested dogs. Tracheal pressure (Ptr), tracheal flow (V) and 3 alveolar pressures (Palv by alveolar capsule) were measured continuously for 20 min at 5 levels of positive end expiratory ...
Burchardi H - - 1994
In acute respiratory failure interstitial oedema, alveolar collapse, and multiple atelectasis are the main mechanisms which lead to increased venous admixture and impaired oxygenation. Thus the lung volume available for pulmonary gas exchange is considerably reduced. Since there is strong evidence that alveolar overdistension causes lung damage ('barotrauma/volutrauma') large tidal ...
Ranieri V M - - 1994
The effects of positive end-expiratory pressure (PEEP) on static ("rapid airway occlusion" technique) and dynamic ("constant flow" technique) volume-pressure (V-P) curves were studied in 19 patients with adult respiratory distress syndrome (ARDS). To describe the shape of both curves, the nonlinear coefficient of a second-order polynomial equation fitted to the ...
Giffin F - - 1994
The effect of positive end expiratory pressure (PEEP) and mean airway pressure (MAP) on respiratory compliance and gas exchange was assessed in children with liver disease. In the first study of 12 patients, PEEP was decreased either by 3 cmH2O below the baseline level (the child's original level) or to ...
Pelosi P - - 1994
We obtained chest computed tomography (CT) sections in 12 normal subjects (controls) and 17 patients with the adult respiratory distress syndrome (ARDS) to investigate regional lung inflation. A basal CT section (just above the diaphragm) was obtained in the supine position at zero cm H2O end-expiratory pressure. In each CT ...
Lillevang S T - - 1994
RATIONALE AND OBJECTIVES: Earlier studies have demonstrated an adverse effect of radiographic contrast media (CM) on granulocyte phagocytosis. Most studies in the past have depended on granulocyte separative procedures that may themselves affect granulocyte functions. This study was performed to evaluate the effect of CM on phagocytosis using a flow ...
Berglund J E - - 1994
OBJECTIVE: Does positive end-expiratory pressure ventilation (PEEP) deteriorate cardiac contractility? DESIGN: By means of echocardiography nine piglets were studies during ventilation with 0, 15 and 25 cmH2O (PEEP). Recordings were made before and after 500 ml of 6% dextran 70. MEASUREMENT AND RESULTS: Right and left ventricular end-diastolic diameters were ...
Jacob L - - 1994
Esophageal replacement after esophagogastric injury caused by ingestion of lye may require the interposition of a retrosternal ileocolic graft. In this new anatomic situation, the mesenteric circulation supplying the graft is subjected to the intrathoracic pressure surrounding the graft. Thus, mesenteric blood flow supplying the graft may be impaired when ...
Romand J A - - 1994
Dynamic hyperinflation, also called intrinsic PEEP (PEEPi,) occurs particularly when high tidal volumes or high respiratory rates are used during mechanical ventilation, although the phenomenon does occur at normal tidal volumes. It is not identified using existing monitoring such as the airway pressure but can be identified by occlusion of ...
Fernandez A - - 1994
OBJECTIVE: To compare the bronchodilating effect of a single drug, ipratropium bromide (IBr), with that of its combination with fenoterol (IBr+F). DESIGN: The study was triple blind and randomized. SETTING: Medical-surgical intensive care unit. PATIENTS: 12 patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) requiring mechanical ventilation for ...
Berglund J E - - 1994
OBJECTIVE: Does ventilation with positive end-expiratory pressure (PEEP) depress myocardial contractility? DESIGN: Ten piglets were anaesthetized and prepared for the measurement of cardiac output (SV) and right (MRAPtm) and left (MLAPtm) mean transmural atrial pressure, the latter serving as indices of preload. 500 ml of autologous blood was re-transfused during ...
Shardonofsky F R - - 1993
The effects of positive end-expiratory pressure (PEEP) on lung tissue resistance (Rti) and dynamic elastance (Edyn,L) were examined separately during histamine-induced lung constriction and after saline lung lavage in anesthetized paralyzed New Zealand White rabbits. During mechanical ventilation in the open-chest state, Rti and Edyn,L were estimated by fitting the ...
Fessler H E - - 1993
Positive end-expiratory pressure (PEEP) commonly decreases cardiac output. The major cause of this is believed to be decreased venous return due to increased right atrial pressure. We hypothesized that when the lungs were hyperinflated they could also restrict venous return by directly compressing the thoracic vena cavae. We measured the ...
Fujita Y - - 1993
This study was undertaken to examine the effect of sevoflurane on right ventricular function, the safety of sevoflurane for one-lung ventilation and the effects of PEEP (positive end-expiratory pressure) to the dependent lung in this model using 12 open-chest sheep. Haemodynamic variables, including cardiac output, mean arterial blood pressure, right ...
Rothen H U - - 1993
Formation of atelectasis is one mechanism of impaired gas exchange during general anaesthesia. We have studied manoeuvres to re-expand such atelectasis in 16 consecutive, anaesthetized adults with healthy lungs. In group 1 (10 patients), the lungs were inflated stepwise to an airway pressure (Paw) of 10, 20, 30 and 40 ...
Rossaint R R Clinic of Anesthesiology and Operative Intensive Medicine, Universitätsklinikum Rudolf Virchow, Free University of Berlin, - - 1993
This study compared the hemodynamic, renal, and hormonal effects of an experimentally induced increase in inferior vena caval pressure (IVCP) [to the same extent as during controlled mechanical ventilation (CMV) with positive end-expiratory pressure (PEEP)] with those of CMV with PEEP. Six volume-expanded conscious chronically tracheotomized dogs were studied under ...
Dreyfuss D - - 1993
Mechanical ventilation with high peak inspiratory pressure and large tidal volume (VT) produces permeability pulmonary edema. Whether it is mean or peak inspiratory pressure (i.e., mean or end-inspiratory volume) that is the major determinant of ventilation-induced lung injury is unsettled. Rats were ventilated with increasing tidal volumes starting from different ...
Cujec B - - 1993
OBJECTIVE: To determine the effect of the presence of a patent foramen ovale on the right-to-left shunt in patients with respiratory failure who receive positive end-expiratory pressure (PEEP). DESIGN: Convenience sample with randomized application of PEEP. SETTING: General intensive care unit of a university teaching hospital. PATIENTS: A total of ...
Fiz J A - - 1993
We studied whether experienced trumpet players can develop higher pressures with their inspiratory and expiratory muscles than untrained subjects. Twelve male trumpet players (mean age, 22.4 +/- 3.3 years) participated in the study. All of them had played the trumpet for at least 4 years and were nonsmokers. Twelve healthy ...
Ninane V - - 1993
Many patients with severe chronic obstructive pulmonary disease (COPD) contract the transversus abdominis (TA) muscle during expiration. The mechanical correlates of this contraction, however, are uncertain. In the present study, we have measured airflow, esophageal (Pes), and gastric (Pga) pressures, the anteroposterior (AP) diameter of the abdomen, and the electromyogram ...
Brüssel T - - 1993
Ten patients with acute respiratory failure (ARF) after coronary artery bypass grafting were studied during conventional mechanical ventilation in the supine and in the prone position. Impaired gas exchange was defined as an inspired oxygen fraction (FIO2) greater than 0.5 to maintain an arterial oxygen tension (PaO2) > or = ...
Moffa S M - - 1993
Laparoscopy is frequently used for diagnosis and treatment of critically ill trauma patients. Its effects on cardiopulmonary performance in the intensive care unit patient population, however, are not well-defined. This study evaluated the effects of positive end-expiratory pressure (PEEP) and carbon dioxide (CO2) pneumoperitoneum on hemodynamic function during mechanical ventilation. ...
Shoptaugh M - - 1993
Pulmonary function measurements were studied on equivalent levels of positive end-expiratory pressure (PEEP) and continuous negative pressure (CNP) while controlling for transpulmonary pressure (TPP). Four adult rabbits were anesthetized, instrumented, and ventilated with intermittent mandatory ventilation by using peak inspiratory pressure (PIP) of 16 cm H2O, PEEP 0 cm H2O, ...
Gentilello L M - - 1993
Conventional management of adult respiratory distress syndrome (ARDS) with high minute ventilation, positive end-expiratory pressure (PEEP), and increased fractional inspired oxygen (FIO2) concentrations may worsen pulmonary injury. The intravascular oxygenator (IVOX) is a device made up of several hundred gas permeable hollow fibers that are inserted into the vena cava ...
Putensen C - - 1993
Knowledge of the pressure/volume (P/V) relationship of the lung may allow selection of tidal volume and positive end-expiratory pressure (PEEP) to optimize gas exchange without adversely affecting lung function or hemodynamics. Ten patients with acute lung injury were stabilized on controlled mechanical ventilation, based on conventional practice, using criteria from ...
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