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PubMed1989

[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↗
PubMed1989

[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↗
PubMed1994

[General introduction to the clinical application of non-invasive respiratory aids].

Intermittent positive pressure ventilation via tracheostomy has been the most common method of providing ventilatory support for patients with respiratory failure since the late 1950s. It is the standard procedure for individuals who suffer from acute respiratory failure, impaired consciousness, and severe restrictive lung disease. However, numerous adverse complications from these invasive techniques have been reported in those who are long-term ventilator users. This paper describes the evolution and current application of non-invasive respiratory aids in both acute and long-term settings. The respiratory function can be aided by applying forces to the body or intermittent pressure to the air ways. The devices are negative pressure body ventilators which act on the body by creating negative pressure around the thorax and abdomen such devices effectively maintain the ventilation of individuals with respiratory failure, but have the shortcomings of bulkiness, high expense, and limitation on the users' activities. The non-invasive positive pressure ventilator applies intermittent pressure directly to the airway by a non-invasive interface; namely mouthpiece, nasal, or face masks. In this way, it can prevent patients from requiring either tracheostomy or endotracheal tube, but is not effective enough to ventilate patients with markedly decreased lung compliance because the high airway resistance provides air leakage from the non-invasive interface. Non-invasive respiratory aids should be the first choice to maintain ventilation for patients with respiratory failure secondary to neuromuscular disorder, because of their benefits of easy application, satisfactory results, fewer complications and early active rehabilitation. Increased understanding of non-invasive respiratory aids should assist in the management of patients with chronic respiratory failure.

Humans↗
PubMed1994

External negative pressure ventilation techniques.

External ventilation was introduced at the beginning of the century to treat acute and chronic respiratory failure. Long-term negative pressure ventilation (NPV) has proved useful in patients with respiratory failure, secondary to a restrictive impairment of neuromusculoskeletal origin. Although NPV may be successfully used in acute-on-chronic respiratory failure in patients with chronic airflow obstruction (CAO), its use in the long-term management of this type of patient seems much less promising. The various types of ventilators, iron lung, pneumo-wrap and cuirass are discussed. All these prostheses, except for the pneumo-wrap, are connected to a pump able to generate negative and positive pressure. NPV must be a controlled ventilation, because an effective trigger is not yet available. The most important feature of the ventilator must be the ability to vary the ventilatory pattern to adapt the machine drive to the patient drive. The goal of NPV is not only to normalize gas exchange, but also to restore an effective spontaneous ventilation. This kind of ventilation has no negative effects on haemodynamics, because it does not vary physiological gradients of transthoracic pressure. However, due to lack of coordination between the respirator and the pharyngeal muscles of the patient, obstructive apnoeas may occur during NPV in sleeping patients.

Humans↗
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↗
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↗
PubMed1970

Negative pressure artificial respiration: use in treatment of respiratory failure of the newborn.

Ninety-one infants with respiratory failure secondary to primary pulmonary disease and with a birth weight of 1000 g. or over have been managed in a negative-pressure respirator (Air-Shields) over a three-year period. Of these the failure in 87 was due to respiratory distress syndrome (RDS) and in four it resulted from massive meconium aspiration. Respiratory failure was indicated initially by arterial blood gas tensions (while breathing 100% O(2)) of Po(2) <40 mm. Hg, pH <7.10 and Pco(2) >75 mm. Hg in the initial 47 cases; these levels were subsequently raised to Po(2) < 50 mm. Hg, pH <7.20 and Pco(2) >70 mm. Hg for the remainder. Fifty-four (59.3%) of the infants survived the use of the respirator and 47 of these (51.6%) were subsequently discharged alive and well. Mean time in hours to normalization of blood gas values while on the respirator were as follows: for Po(2), 10.5; for pH, 11.6; and for Pco(2), 22.6. These values indicate that the respirator is more efficient in promoting oxygenation (raising Po(2)) than ventilation (lowering Pco(2)). They also suggest that the observed acidosis is in large part secondary to the hypoxia rather than the result of co(2) retention. For the survivors the average time of total respirator dependency before commencement of weaning was 53.7 hours. All the infants were managed without the use of endotracheal tubes although the use of the respirator and/or administration of 100% oxygen were either continuous or intermittent for periods of up to two weeks. There have been no instances of so-called respirator lung disease in the survivors or in those who died, which suggests that the use of high oxygen concentration by itself is not the major factor in the pathogenesis of this complication.

Age Factors↗
PubMed1992

[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↗