PubMed Health⌕ Search

SEARCH · PubMed Health

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources
PubMed1994

Contraction and relaxation of upper airway muscles during expiratory application of negative pressure at the mouth.

Upper airway muscles (UAM) are activated during inspiration, but little is known about their activity during expiration. We studied six healthy volunteers in supine position. Negative pressure (-10 to -30 cm H2O) was applied cyclically at the mouth during expiration. Subjects actively breathed during inspiration and either contracted or relaxed their UAM during expiration. Supraglottic pressure (Psg) was measured with a catheter with the tip at the supraglottic level. During relaxation, but not during contraction, there was expiratory flow limitation (FL) accompanied by high frequency pressure and flow oscillations (70 +/- 5.7 Hz at -30 cm H2O). The average linear supraglottic resistance was higher during relaxation than during contraction at both -10 and -20 cm H2O (p < 0.05), but not at -30 cm H2O. Amplitude of expiratory genioglossus electromyogram was 3.6 +/- 2.5 mm during quiet breathing, 7.0 +/- 3.8 mm during contraction (p < 0.05) and 4.1 +/- 1.8 mm during relaxation. Average mouth pressure, which immediately preceded pressure (and flow) oscillations was -2.1 +/- 0.9 cm H2O. In one subject cineradiography of the neck during expiratory application of -30 cm H2O showed anterior flexion and high frequency oscillations of the soft palate during relaxation. During contraction, the soft palate was close to the posterior pharyngeal wall without oscillations. We conclude that cyclically applied negative pressure at the mouth during expiration produced expiratory flow limitation during relaxation but not during contraction, and that expiratory contraction of UAM stabilizes upper airways during negative pressure application at the mouth.

Adult↗
PubMedDate not supplied

Pulmonary mechanics generated by positive end-expiratory and continuous negative pressure.

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, CNP 0 cm H2O, inspiratory time 0.3 seconds, rate 20/min, and fraction of inspired oxygen of 0.3. Subsequently, equal amounts of PEEP and CNP were alternated for 15-minute ventilation periods. PIP was changed to approximate the TPP in each PEEP/CNP pair. There was a significant decrease in PCO2 and increase in pH, mechanical tidal volume, minute ventilation, functional residual capacity, and total dynamic compliance on CNP. These differences could not be explained by changes in TPP.

Animals↗
PubMed1993

[Home intermittent negative pressure ventilation in a case of chronic respiratory failure due to old tuberculous pleuritis].

A 64-year-old male with a history of tuberculous pleuritis at age 29 had received home oxygen therapy since age 58 because of chronic respiratory failure. He was admitted with symptoms of dyspnea at rest and myoclonus at age 62. Because CO2 narcosis occurred twice, we performed intermittent negative pressure ventilation (INPV) after short-term positive pressure ventilation with transnasal intubation. He has received INPV for 7 hours every day at his home for 20 months without acute exacerbation of respiratory failure, and his activity of daily life subsequently improved. In conclusion, INPV seems to be useful for patients with chronic hypercapnic respiratory failure due to lung disease.

Chronic Disease↗
PubMed1993

Intermittent negative pressure ventilation in patients with restrictive respiratory failure.

Thirty one patients in stable respiratory failure (arterial oxygen tension (PaO2) 67 +/- 20 mmHg (8.9 +/- 2.7 kPa) and arterial carbon dioxide tension (PaCO2) 59 +/- 10 mmHg 7.9 +/- 1.3 kPa)), secondary to non-obstructive ventilatory impairment, were treated by intermittent negative pressure ventilation (INPV), using a pneumowrap or poncho during the night. Daytime arterial blood gas measurements, taken before and after the ventilation, revealed a substantial improvement in PaO2, PaCO2 and maximal inspiratory pressure (Pimax). This improvement persisted during the six month follow-up of home nocturnal ventilation. The polysomnographic, recording during mechanical ventilation by poncho, in five patients, showed a general improvement in the quality and structure of sleep. All patients returned to normal arterial oxygen saturation (SaO2) values (> 90%), except for one. In three patients, the appearance of obstructive events was noted but the desaturation that they caused was, remarkably, lower than that caused by central events in baseline recording. We conclude that non-invasive treatment by INPV, in patients with neuromuscular and chest wall disease, is the method of choice as an alternative to intermittent positive pressure ventilation and to tracheostomy.

Adult↗
PubMed1988

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↗
PubMed1993

Phrenic nerve pacing--an alternative to positive pressure ventilation: the required nursing care.

Phrenic nerve pacing as a method of ventilation was first recognized in 1783. For years, this technique was not used because of the lack of practical technology. Interest in phrenic nerve pacing was renewed in the 1960s with the development of a radio frequency transmission system. Applicable to a limited patient population, phrenic nerve pacing has several benefits over positive-pressure ventilation. Benefits include greater patient mobility, verbal articulation, less mechanical noise, and breathing by natural negative-pressure. This article provides information for nurses who care for patients ventilated by phrenic nerve pacing.

Diaphragm↗
PubMed1992

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↗
PubMed1988

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↗
PubMed1993

Pulmonary edema following post-operative laryngospasm: a case report and review of the literature.

The pathophysiology of acute, negative-pressure pulmonary edema following post-anesthetic laryngospasm (PLPE) is unclear. We present a patient and review the literature to propose etiology and management. Nineteen reported patients (3 female, 16 male, aged 3 months to 60 years) with PLPE had undergone 10 otolaryngologic, three orthopedic, four skin/soft tissue, one intraabdominal, and one ophthalmologic procedures. Twelve patients (63%) had significant medical history. Initial intubation was performed without difficulty in 17 patients, there were no predisposing trends in anesthetic management, and post-anesthetic extubation was performed without difficulty in 18 patients. Thirteen patients developed laryngospasm in less than 2 minutes. Eight were ventilated with bag/mask, 15 required reintubation, and nine required paralysis. Onset of PLPE was less than 3 minutes in 12 patients; chest roentgenograms showed edema in 17 patients. Mechanical ventilation was required for less than 24 hours in all patients. PLPE cleared in less than 24 hours in most patients. Furosemide was administered in nine patients, digoxin in one, theophylline in two, and steroids in four patients. The precise pathophysiologic mechanism of PLPE is unclear despite numerous proposed mechanisms. PLPE resolves rapidly with short-term ventilatory support. Use of diuretics/airway dilators is variable, and their contribution to management is unclear.

Adolescent↗