[Continuous positive and negative pressure ventilation in normal subjects].
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Adult↗
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Results for “Ventilators, Negative-Pressure”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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[Can the respiratory muscles rest during intermittent negative pressure ventilation (INPV) in COPD?].
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Humans↗
[The effect of pressure support ventilation on breathing patterns and the work of breathing].
We assessed breathing patterns during pressure support ventilation (PSV) and its relationship with the work of breathing in 10 postoperative patients. With increasing levels of pressure support, minute ventilation and tidal volume increased with a decrease in respiratory frequency. Increased minute ventilation was achieved by increased mean inspiratory flow. Duty cycle, however, decreased with PSV. This decrease might allow the diaphragm a longer rest period between contractions, which might decrease the risk of diaphragmatic fatigue. Furthermore, PSV reduced the inspiratory work added by a ventilator to near zero. Oxygen consumption was also decreased with PSV. We conclude that PSV improved the breathing patterns and minimized the work of breathing spontaneously via a ventilator.
Adult↗
Negative pressure devices in pediatric practice.
Pediatric nurses are seeing a renewed interest in the use of negative pressure ventilators in the hospital and home setting. Although body ventilators are a novelty to many nurses, they also present several challenges for safe and supportive care.
Child↗
[Nocturnal hypoxia and treatment in the patients with Duchenne muscular dystrophy].
Overnight monitoring using pulse oximeter was performed on 10 patients with Duchenne muscular dystrophy (mean age, 22; mean %FVC, 26.6%; mean PaCO2, 54.1 Torr; mean PaO2 76.6 Torr). At the same time, spinal deformity and obesity were examined. In 4 patients, the measurement of the chest and abdominal wall movements were performed by using a respisomnograph. In 5 patients, nocturnal desaturation below 95% occurred despite normal daylight blood gas tension. In the other 5 patients with hypercapnea of over 50 Torr, nocturnal desaturation below 85% occurred, and 3 patients required oxygen supplementation treatment using a low concentration of oxygen. In 4 patients with hypercapnea over 50 Torr, cuirass-assisted respirators were used and they prevented mild nocturnal desaturation, but did not have much effect on severe nocturnal desaturation. Nocturnal desaturation was associated not only with hypopnea and hypoventilation, but with normal chest and abdominal wall movement using cuirass-assisted respirators. It seemed that desaturation with normal respiratory pattern can be attributed to ventilation-perfusion mismatching. The severity of the desaturation did not always correlate to the spinal deformity and the obesity.
Adolescent↗
Short term effect of intermittent negative pressure ventilation in COPD patients with respiratory failure.
Ten patients with stable chronic obstructive pulmonary disease (COPD) and hypercapnic respiratory failure were randomly submitted to intermittent negative pressure ventilation (INPV) 6 h per day for 5 consecutive days by either a cuirass or pneumo wrap ventilator. The effects were assessed by measurements of spirometry, blood gases, maximal inspiratory (MIP) and expiratory (MEP) pressures, 12 minutes walking distance test (12 mwd), sensation of dyspnoea by a visual analogue scale (VAS) and diaphragmatic electromyographic activity (Edi). Edi was recorded during INPV sessions in only 7 patients. The same measurements apart from Edi were also performed in 8 matched control patients randomly submitted to conventional physiotherapy. During INPV, Edi activity was reduced, at least temporarily down to 50% of baseline values. Comparison of baseline with post INPV values showed no changes in thoracic gas volume (TGV), forced expiratory volume in one second (FEV1), FEV1/forced vital capacity (FVC), arterial oxygen partial pressure (Pao2) and MEP; significant improvements were seen in MIP, vital capacity (VC), VAS, and 12 mwd only in patients submitted to INPV. A significant improvement in PaCO2 was observed in both groups of patients. We conclude that INPV may be effective in improving the functional reserve of the inspiratory muscles in selected COPD patients with hypercapnic respiratory failure and signs of inspiratory muscle dysfunction.
Breathing Exercises↗
Respiratory muscle insufficiency in acute respiratory failure of subjects with severe COPD: treatment with intermittent negative pressure ventilation.
Nine subjects with severe chronic obstructive pulmonary disease (COPD) in acute respiratory failure (ARF) and with marked weakness of the respiratory muscles (Group A) underwent intermittent negative pressure ventilation by means of an iron lung (8 h daily for 7 days). Seven subjects with COPD in stabilized chronic respiratory failure (Group B) were studied as controls and submitted to the same medical therapy without ventilator treatment. Functional respiratory tests were performed before and after 7 days of treatment. After ventilatory treatment, Group A showed an increase of maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), vital capacity (VC), arterial oxygen tension (PaO2), pH and a decrease of residual volume (RV), total lung capacity of (TLC) and arterial carbon dioxide tension (PaCO2) (all statistically significant). No improvement was ascertained in the functional parameters of Group B. The expiratory muscles seem to play a determining role in ARF. We conclude that the iron lung is a useful therapeutic defence in removing muscular fatigue and in restoring a good level of respiratory compensation of ARF in severe COPD.
Female↗
[Hemodynamic study of negative pressure ventilation using diaphragm pacing].
A negative pressure ventilation (NPV) by unilateral or bilateral diaphragm pacing (DP) was prepared for canine experiments. A shift from positive pressure ventilation (PPV) to NPV resulted in elevation of mean aortic pressure, increase in stroke volume and depression of mean pulmonary arterial pressure. Examination of the interaction between respiratory cycle and cardiac function during PPV, disclosed a reduction of right ventricular stroke volume and elevation of mean aortic and right ventricular end-diastolic pressure at end inspiration, compared to those at end expiration. During NPV with DP, left ventricular stroke volume, heart rate and mean aortic pressure were increased immediately after DP (immediately after inspiration) compared to those at end expiration. The experimental model of DP, in which respiratory condition could be easily altered, was considered to be useful to evaluate the effect of NPV on cardiac function.
Animals↗
[Right ventricle support after lung resection].
It is very important to establish a method of determining the influence of lung resection on right ventricular function and to devise some therapeutic methods of supporting the right ventricle. However, there has been no systematic research on these issues. We found that echocardiographic demonstrated abnormal motion of the ventricular septum after right pneumonectomy and of the left ventricular wall after left pneumonectomy. We developed a triggered cuirass respirator and showed that it could support the right heart after a lung resection. We also found that the injection of SF6 Gas into the postpneumonectomy pleural space might be useful in supporting the right heart after a pneumonectomy.
Adult↗
[The effect of body respirator on the desaturation during the night in Duchenne muscular dystrophy].
Recently body respirator (BR) has been used to control respiratory failure in patients with late stage Duchenne muscular dystrophy (DMD). We examined the effect of BR using a pulse oximeter. Arterial oxygen saturation (SaO2) for the night (21:00-7:00) was monitored in 15 DMD patients (5 cases without BR, 3 cases with BR partially for the night and 6 cases with BR all night long) and the desaturation (SaO2 less than 90%) time was followed three times (Jan. '87, Nov. '87, Apr. '88) in each patient. Desaturation time did not increase in 4 cases without BR. But in one case without BR it increased so much that we decided to put the patient on BR. In 3 cases with BR partially for the night, desaturation was well controlled when they used BR. No marked increase of desaturation was found in 4 cases with BR all night long. 2 of these cases were changed from cuirass type BR to jacket type BR and were getting on satisfactorily. Thoracic cage expansion of jacket type was larger than that of cuirass type, and it was found that jacket type was valuable. Also, we investigated the cause of desaturation by recording SaO2, nasal flow, thoracic cage motion and abdominal motion at the same time by making use of a polygraphy. The result showed that the main cause of desaturation was the resistance of thoracic cage motion against BR. And we think research and development is needed.
Adolescent↗
Home mechanical ventilation.
Recently, interest in the use of mechanical ventilation outside the hospital setting has been increasing. Patients with various types of chronic respiratory failure may benefit from this approach. Evaluation for long-term mechanical ventilation necessitates assessment of the underlying disease process, the goals of the medical team, and the needs of the patient and family. Externally applied negative-pressure devices can provide adequate ventilation for many patients, particularly those with neuromuscular diseases. Positive-pressure ventilation by means of a tracheostomy provides greater control of the airway, allows adjustment of tidal volume and minute ventilation, and may be delivered by portable equipment. Ongoing care and support services in the home must be provided. A variety of mechanical devices and new techniques of ventilator support have made home mechanical ventilation a realistic option for long-term care.
Adult↗
Historical perspectives on the development and use of mechanical ventilation.
Contemporary advancements in cardiothoracic and abdominal surgical procedures have been historically dependent on the development and adoption of controlled airway management, specifically endotracheal intubation, controlled positive-pressure ventilation, and the use of automatic positive-pressure mechanical ventilators. More than 400 years elapsed before the 16th Century theories of Paracelsus and the demonstrations of Vesalius were routinely adopted to solve the "pneumothorax problem" that prevented complicated or prolonged surgical procedures within the pleural cavity. Acceptance and implementation of controlled positive-pressure ventilation was impeded for decades by the inability to maintain and protect the airway. Consequently, emphasis on the development of mechanical ventilation was directed toward machinery that provided safer negative-pressure respiratory support. The introduction of curare into European anesthesia practice and the adoption of protective airway practices during the poliomyelitis epidemics led to routine use of controlled positive-pressure ventilation and construction of dependable machinery. Laboratory investigations, exploring complications from cardiothoracic surgery, brought about American acceptance and established controlled positive-pressure mechanical ventilation as an indispensable part of conventional intraoperative management.
Europe↗
Ventilatory responses to increased blood flow and decreased lung volume in awake dogs.
The effect of decreased lung volume on ventilatory responses to arteriovenous fistula-induced increased cardiac output was studied in four chronic awake dogs. Lung volume decreases were imposed by application of continuous negative-pressure breathing of -10 cmH2O to the trachea. The animals were surgically prepared with chronic tracheostomy, indwelling carotid artery catheter, and bilateral arteriovenous femoral shunts. Control arteriovenous blood flow was 0.5 l/min, and test flow level was 2.0 l/min. Arterial blood CO2 tension (PaCO2) was continuously monitored using an indwelling Teflon membrane mass spectrometer catheter, and inhaled CO2 was given to maintain isocapnia throughout. Increased fistula flow alone led to a mean 52% increase in cardiac output (CO), whereas mean systemic arterial blood pressure (Psa) fell 4% (P less than 0.01). Negative-pressure breathing alone raised Psa by 3% (P less than 0.005) without a significant change in CO. Expired minute ventilation (VE) increased by 27% (P less than 0.005) from control in both of these conditions separately. Combined increased flow and negative pressure led to a 50% increase in CO and 56% increase in VE (P less than 0.0025) without any significant change in Psa. Effects of decreased lung volume and increased CO appeared to be additive with respect to ventilation and to occur under conditions of constant PaCO2 and Psa. Because both decreased lung volume and increased CO occur during normal exercise, these results suggest that mechanisms other than chemical regulation may play an important role in the control of breathing and contribute new insights into the isocapnic exercise hyperpnea phenomenon.
Animals↗
The negative-pressure respirator: an improved design.
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Body Weight↗
[Hypoventilation due to disconnection of the vaporizer and negative-pressure leak test to find disconnection].
Most of Ohmeda anesthesia machines have a outlet check valve located in the low-pressure circuit, and this influences the type of leak test greatly. We report a case of hypoventilation due to a gas leakage from the junction of two vaporizers, Fluotec 3 and Enfluratec of Ohio 30/70. This gas leakage was not discovered preoperatively by performing traditional leak test of squeezing the bag filled with oxygen. Following intubation of the trachea the patient was paralyzed and mechanically ventilated. Her vital signs were stable and operation was started. Soon thereafter, she became hypertensive in spite of increases in concentration of enflurane and supplemental doses of fentanyl and diltiazem. ETCO2 showed 7.4% and spontaneous respiration started. We checked anesthesia machine and found a gas leakage at the junction of two vaporizers. Anesthesia machine was exchanged. The remainder of the procedure was uneventful and the patient showed a normal recovery. The outlet check valve closes when back-pressure is exerted on it, and a vulnerable area including flow tubes and vaporizers is not tested by the traditional positive-pressure leak test squeezing bag. Ohmeda recommends the use of a negative pressure leak test with suction bulb device. We propose manufacturers to place a cation on anesthesia machine such as -- "Negative-pressure leak test is inevitable because of presence of outlet check valve."
Anesthesiology↗
Reflex effects and receptor responses to upper airway pressure and flow stimuli in developing puppies.
We studied the changes in breathing pattern due to pressure and airflow stimuli applied to isolated upper airway in nine 1- to 14-day-old and six 29- to 35-day-old anesthetized puppies breathing through a tracheostomy. Negative-pressure and flow, both inspiratory and expiratory, altered the breathing pattern only in the 1- to 14-day-old puppies, whereas positive pressure was ineffective in both age groups. Negative pressure caused apnea in 12% of the trials, expiratory flow in 18%, and inspiratory flow in 21%. When apnea did not occur there was a significant prolongation of inspiratory and expiratory time and a decrease of tidal volume of the first breath following the application of negative pressures. Section of the superior laryngeal nerves abolished the responses to pressure and flow. In nine 1- to 14-day-old and four 29- to 35-day-old puppies we recorded the activity of single units of the superior laryngeal nerves. We identified specialized receptors responding to pressure (68.5%), flow (2.7%), and contraction of upper airway muscles (drive, 28.8%). All types of receptors had a prevalent inspiratory-related activity. In the younger age group the discharge rate of pressure receptors at comparable negative pressures was lower than in older puppies. The strong inhibitory influences originating from the upper airway in the early stages of development presumably reflect different integrative properties of the central nervous system.
Animals↗
Atrial receptors and renal function.
The hypothesis that receptors in the heart or pulmonary vasculature initiate a reflex that influences urine flow was derived from experiments designed to evaluate the effect of mechanical ventilation on renal function. These experiments indicated that urine flow usually decreases during positive-pressure breathing and usually increases during negative-pressure breathing. It was surmised that impulses from certain cardiopulmonary receptors affect the secretion of ADH, which in turn influences urine flow. A subsequent investigation appeared to localize the pertinent receptors to the left atrium, but the results of this particular investigation were influenced by several complication factors that have not been widely appreciated. The apparent localization of volume-regulating recpetors to the left atrium and the accumulating evidence that atrial receptors do respond to changes in atrial pressure or atrial volume triggered a myriad of further studies on the function of left receptors. Nearly all these studies employed indirect techniques that produced changes in systemic and pulmonary hemodynamics in addition to changes in left atrial pressure. Nevertheless, it often was assumed that if changes in left pressure were produced, any concomitant changes in circulating ADH or in urine flow were attributable to a reflex elicited from atrial receptors. Mush of the data obtained were interpreted as being compatible with the elft atrial volume-receptor hypothesis, but very liggle of the data pertained to left atrial receptors specifically.
Animals↗
Maximal static pressures and lung volumes in a child with Guillain-Barré syndrome ventilated by a cuirass respirator.
Serial maximal static pressure and lung volume measurements were made in a child with Guillain-Barré syndrome and respiratory failure. The patient received successfully ventilatory support for seven weeks with the use of a cycled negative-pressure cuirass-type respirator obviating prolonged intubation and tracheostomy. The fall in VC preceded the loss of respiratory muscle strength (RMS) and lagged behind RMS in the return towards normal values. There was a disproportionate loss of lung volume (lowest VC, 220 to 250 ml, 11 to 12 percent of normal) as compared to maximal static pressures (lowest PImax, 60 cm H2O, lowest PEmax, 47 cm H2O). The disproportion was greater than that previously reported in adults. The greater loss in lung volume may be due to greater chest wall compliance in the child, resulting in less outward recoil of the chest wall and subsequently more microatelectasis with denervation of the chest wall musculature. Loss of lung volume resulted in a smaller surface area over which the respiratory muscles exerted their force. Thus, pressure being equal to force divided by surface area, could be relatively maintained and not reflect the extent of the loss of muscle force.
Child↗