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PubMed1991

Acute effects of external negative pressure ventilation in chronic obstructive pulmonary disease compared with normal subjects.

This study compares the acute physiological effects of external negative pressure ventilation (ENPV) in normal subjects and patients with chronic obstructive pulmonary disease (COPD). The equipment consisted of an airtight jacket (Pneumosuit) and vacuum pump. Minute ventilation (Ve) was recorded using a light-emitting turbine transducer. Oxygen uptake (VO2) and carbon dioxide output (VCO2) were calculated every 30 s. Measurements were made at rest and during ENPV with pressures of -20 cmH2O and -40 cmH2O. The ventilator rate was fixed at 16.min-1. In 10 normal subjects, Ve increased from 8.6 to 22.9 l.min-1 (p less than 0.01) accompanied by an increase in VCO2 from 0.25 to 0.39 l.min-1 (p less than 0.01). In 10 normocapnic COPD patients (arterial carbon dioxide tension (PaCO2) less than 6.0 kPa) Ve increased from 11.5 to 17.1 l.min-1 (p less than 0.01) whilst in 10 hypercapnic patients (PaCO2 greater than 6.0 kPa) Ve increased from 9.7 to 12.4 l.min-1 (p less than 0.01). A change in VCO2 was not detected in the COPD patients, and VO2 did not change in any group. Arterial blood samples were obtained in eight hypercapnic patients. Baseline mean physiological deadspace ventilation (VD) was calculated to be 4.9 l.min-1 (56% of Ve) whilst Ve was 8.8 l.min-1 in this subgroup. During ENPV, arterial oxygen tension (PaO2) increased from 6.8 to 8.2 kPa (p less than 0.01) whilst PaCO2 decreased from 6.8 to 5.8 kPa (p less than 0.01) suggesting that despite the large physiological deadspace, a significant increase in alveolar ventilation had occurred. In advanced COPD, thoracic compliance falls and limits the ventilatory response to ENPV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Effects of continuous negative extrathoracic pressure ventilation (CNETPV) on gas exchange and hemodynamics in dogs with oleic-acid-induced pulmonary edema].

To investigate usefulness of continuous negative extrathoracic pressure ventilation (CNETPV) as a method of respiratory care for pulmonary edema, we compared effects of CNETPV on gas exchange and hemodynamics with those of CPPV in dogs with oleic-acid-induced pulmonary edema. End-expiratory negative extrathoracic pressure was adjusted to obtain the same increase in functional residual capacity as that obtained with PEEP of 10 cmH2O. Transmural pressure was calculated by subtracting intrapleural pressure from intravascular pressure. Both CNETPV and CPPV improved gas exchange, and changes in PaO2 and venous admixture were similar with two ventilatory modes. During CNETPV, PvO2 and oxygen delivery were significantly greater than those in CPPV. CPPV did not alter transmural filling pressures but decreased cardiac output, whereas CNETPV increased transmural filling pressure and preserved cardiac output. These results indicate that CNETPV can offer comparable improvement in gas exchange with CPPV, when two ventilatory modes are matched for lung volume. In addition, these results suggest that CNETPV may be superior to CPPV because of less depression of cardiac output and greater oxygen delivery to organs.

Animals↗
PubMed1991

[Respiratory failure and its care in Duchenne muscular dystrophy].

Respiratory failure is the major cause of death in patients with Duchenne muscular dystrophy (DMD). In this report we retrospectively examined the clinical courses, pulmonary function, progression of scoliosis and the time of assisted ventilation. Forty nine patients, aged 2 to 27 years were studied and thirty eight patients of them were examined twice in some intervals. The subjects of examinations included pulmonary function studies consisting of spirometry, measurement of the thoracic scoliosis measured according to the method of Cobb and room air arterial blood gas values. The results were the following; 1) The decline in percentage values of vital capacity (%VC) began at age 8 or 9 and decreased consistently with age. Finally %VC reached under 10 percent at mean age of 21.53 with respiratory failure. 2) Thoracic scoliosis measured according to the method of Cobb increased further with advancing age. The greater the angle of curvature, the more likely the development of respiratory failure. 3) Sixteen patients received negative pressure ventilator (chest respirator: CR) between 16.5 and 25.1 years of age. Twelve patients used part-time (mainly night-time) ventilator and four patients used it in full-time. The average PaCO2 and PaO2 before administration of ventilator were 67.49 mmHg and 71.46 mmHg, respectively. The levels after ventilation were 58.01 mmHg (PaCO2) and 82.09 mmHg (PaO2).

Adolescent↗
PubMed1990

[Tuberculosis sequelae: pathophysiological aspect (ventilation)].

The percentage of the patients with PaCO2 more than 60 Torr and PaO2 more than 50 Torr were 13% in the patients with tuberculosis sequela (N = 502) and 4% in the patients with chronic obstructive lung disease (COLD, N = 727), who were treated with home oxygen therapy in the western region of Japan. Patients with chronic respiratory failure caused by tuberculosis sequela have higher PaCO2 than patients with COLD. Although the prognosis of patients with hypercapnia and moderate hypoxemia is not necessarily poor, some patients may need treatment for severe hypoventilation to prevent respiratory muscle fatigue and abnormal breathing during sleep. In this study, nine patients with hypercapnic chronic respiratory failure caused by tuberculosis sequela were ventilated by Chest Negative Pressure Ventilation (CNPV). The patients were monitored as in polysomnography by transcutaneous PCO2 (PtcCO2) electrode and Respiratory Inductance Plethysmography (RIP). Tidal volume induced by CNPV was larger during mouth breathing (504 +/- 128 ml, mean +/- s.d.) than during nose breathing (438 +/- 109 ml) calculated from RIP in awake state (N = 7). Oxygen saturation measured by ear oximeter and PtcCO2 were 94.4 +/- 2.9% and 57.8 +/- 12.2 Torr in awake state. Following CNPV SaO2 and PtcCO2 were 95.7 +/- 3.0%, 42.7 +/- 12.1 Torr in awake state (N = 9) and 93.0 +/- 4.4%, 57.0 +/- 15.7 Torr in Non-REM sleep (N = 5), respectively. CNPV is effective in these patients in awake state. During Non-REM sleep, CNPV maintains the PtcCO2 level only in awake state.

Aged↗
PubMed1990

[Intermittent negative pressure aspiration in the treatment of chronic pneumothorax with report of 35 cases].

The authors reported 35 cases of chronic pneumothorax who failed to the treatment with bed rest, gas aspiration from cavity and simple closed drainage. In order to re-expand the collapsed lung, intermittent negative pressure aspiration and periodic injection of drugs into pleural cavity was performed with good results. During and after the negative pressure aspiration. There was no severe side effect such as hypotension, shock.

Adolescent↗
PubMed1990

[The tidal volume, arterial blood gas and functional residual capacity changes during negative extra-thoracic pressure ventilation and positive airway pressure ventilation].

Eight patients, of ASA physical status I or II soon after total knee replacement under general anesthesia, were studied to compare negative extra-thoracic pressure ventilation (NETPV) with positive airway pressure ventilation (PAPV). The measured parameters during the two ventilatory modes were tidal volume, arterial blood gas and functional residual capacity change (delta FRC). Tidal volume obtained during NETPV was 60 to 80% of that during PAPV at the same absolute values of peak pressure. delta FRC obtained during NETPV was 30 to 40% of that during PAPV at the same absolute values of end-expiratory pressure. A decrease in the esophageal pressure was 4 to 11cmH2O at an end-expiratory negative extra-thoracic pressure of -10 to -20 cmH2O. When the patients were ventilated with the same values of minute ventilation on NETPV and PAPV, there was no significant difference in blood gas values. These findings suggest that efficiency of NETPV is less than that of PAPV at the same absolute working pressure but pulmonary gas exchange of NETPV is almost equal to that of PAPV at the same minute ventilation in the normal lung.

Aged↗
PubMed1990

Effect of positive and negative pressure breathing on sodium and water excretion.

Positive and negative pressure breathing purportedly alter renal sodium and water excretion by modifying hemodynamics and/or hormonal regulators of sodium and water homeostasis. To test this hypothesis we monitored hemodynamic and hormonal responses in seven normal men to (1) continuous positive pressure breathing (19 +/- 1 mm Hg for 30 minutes) after water loading (urine volume = 15 +/- 1 ml/min); and (2) continuous negative pressure breathing (11 +/- 1 mm Hg for 30 minutes) after maintenance water ingestion (urine volume = 4 +/- 1 ml/min), in random order. Each study was repeated on a control day without pressure breathing. Results were as follows (mean +/- SE, p less than 0.05): (1) continuous positive pressure breathing decreased urinary sodium from 0.28 +/- 0.07 to 0.17 +/- 0.04 mEq/min, increased atrial natriuretic peptide from 34.2 +/- 4.9 to 48.5 +/- 6.9 pg/ml, and had no effect on osmolar and free water clearances, cardiac output, plasma renin activity, or plasma aldosterone and plasma arginine vasopressin levels; and (2) continuous negative pressure breathing increased free water clearance from 0.6 +/- 0.7 to 4.5 +/- 1.2 ml/min, urine volume from 4.0 +/- 0.8 to 8.9 +/- 1.3 ml/min, and cardiac output from 5.1 +/- 0.4 to 7.0 +/- 0.6 L/min in a proportional manner (r = 0.40, p less than 0.01) and had no effect on osmolar clearance, urinary volumes of sodium and potassium, plasma renin activity, plasma aldosterone, atrial natriuretic peptide, and arginine vasopressin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Effects of negative extra-thoracic pressure ventilation on respiratory system and hemodynamics in normal dogs].

The effects of negative extra-thoracic pressure ventilation (NETPV) on respiratory system and hemodynamics were examined in ten normal dogs. Changes of the parameters obtained during intermittent NETPV (INETPV), and NETPV with negative end-expiratory pressure (CNETPV) were compared with those during IPPV and CPPV. Animals' chests and upper abdomens were confined in an acryl box. In INETPV and CNETPV, the dogs were ventilated with the negative extra-thoracic pressure ventilator (Kimura, OKT-100). Positive and negative pressure ventilation was carefully matched for tidal volume and the increase in FRC obtained with PEEP and the end-expiratory negative extra-thoracic pressure (EENETP). EENETP of -11.6 cmH2O produced the same FRC change as PEEP of 10.6 cmH2O did. Gas exchanges did not differ in any modes. INETPV did not change any hemodynamic parameters without PAP. In CNETPV, heart rate increased, and CVP, cardiac index (CI) and stroke volume (SV) decreased significantly (P less than 0.05), but tmCVP and tmPCWP did not change. The decreases of CI and SV (100----89.1, 88.8%) in CNETPV were significantly smaller when compared with CPPV (100----78.8, 74.5%). In CPPV, meanBP, CVP, tmCVP, tmPCWP, CI, SV changed significantly. The mechanisms of the decrease of CI and SV by CNETPV seemed to be different from those by CPPV.

Animals↗
PubMed1990

[Effects of negative extra-thoracic pressure ventilation on extravascular lung water volume and central blood volume in normal dogs].

In negative extra-thoracic pressure ventilation (NETPV), lung water volume and central blood volume (CBV) could increase because of increased venous return and intensified negative interstitial pressure. The effects of NETPV on the extravascular lung water and CBV were examined in ten normal dogs by the double-indicator method using Na and cold water. The lung water volume measured by the method (EVTV) was compared with the lung water volume measured by the gravimetric method (EVLW) in 17 dogs. EVTV did not show any significant change in any ventilation modes compared with IPPV. CBV decreased from 21.9 ml.kg-1 to 19.2 ml.kg-1 in CPPV compared with IPPV (P less than 0.05). EVTV correlated well (r = 0.91, P less than 0.001) with EVLW. In normal dogs, NETPV did not change the lung water volume and CBV. NETPV dogs do not seem to have any disadvantage in respect of lung water volume compared with conventional positive pressure ventilations.

Animals↗
PubMed1990

[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↗
PubMedDate not supplied

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↗
PubMed1990

[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↗
PubMed1990

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↗
PubMed1990

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↗
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↗