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At least 37 records · Page 2Linked to original sources
PubMed1992

Hemodynamic differences between continual positive and two types of negative pressure ventilation.

In seven anesthetized dogs, ventilated with matching lung volumes, tidal volumes, and respiratory rates, we compared the effects on cardiac output (CO), arterial venous oxygen saturation difference (SaO2 - SVO2), and femoral and inferior vena cava pressure (1) intermittent positive pressure ventilation with positive end-expiratory pressure (CPPV); (2) iron-lung ventilation with negative end-expiratory pressure (ILV-NEEP); (3) grid and wrap ventilation with NEEP applied to the thorax and upper abdomen (G&W-NEEP). The values of CO and SaO2 - SVO2 with ILV-NEEP were similar to those with CPPV. However, with G&W-NEEP as compared with ILV-NEEP, mean CO was greater (2.9 versus 2.6 L/min, p = 0.02) and mean (SaO2 - SVO2) was lower (26.6% versus 28.3%, p = NS). Mean PFEM-IVC was higher with G&W-NEEP than with the other types of ventilation. We conclude that (1) ILV-NEEP is hemodynamically equivalent to CPPV and (2) G&W-NEEP has less adverse hemodynamic consequences. has less adverse hemodynamic consequences.

Animals↗
PubMed1992

Continuous negative extrathoracic pressure ventilation, lung water volume, and central blood volume. Studies in dogs with pulmonary edema induced by oleic acid.

The effect of continuous positive-pressure ventilation (CPPV) on extravascular lung water volume has been investigated, but there is only one report which studied the effect of continuous negative extrathoracic pressure ventilation (CNETPV). The effect of CNETPV on central blood volume (CBV) has not been studied. Changes in intrathoracic pressure by CNETPV may alter lung water volume and CBV. In this study the effects of CNETPV on lung water volume and CBV were compared with those of intermittent positive-pressure ventilation (IPPV) and CPPV in dogs with pulmonary edema induced by oleic acid. Nine mongrel dogs were anesthetized and given oleic acid at 0.06 ml/kg intravenously to induce pulmonary edema; CNETPV was applied with a cuirass and a negative thoracic pressure ventilator (Kimura OKT-100) for 1 h. Extravascular lung water volume (as extravascular thermal volume [EVTV]) and CBV were estimated with the double-indicator dilution method using thermal-sodium; PEEP and continuous negative extrathoracic pressure were matched to produce the same increments in FRC. The EVTV increased during CNETPV but did not change during CPPV. The CBV decreased during CPPV but did not change during CNETPV. An increase of transmural pulmonary microvascular pressure was thought to be one of the reasons for the increase in EVTV with CNETPV.

Animals↗
PubMed1992

An artifact induced by negative pressure ventilation.

This report draws attention to an artifact that influences the qualitative information gained from respiratory inductance plethysmography during negative pressure ventilation with a cuirass. This artifact may prevent identification of upper airway obstruction, a manageable complication of this mode of ventilation.

Artifacts↗
PubMed1992

Iron lung treatment of subjects with COPD in acute respiratory failure. Evaluation of short- and long-term prognosis.

We evaluated retrospectively the short-term and the long-term prognosis of 105 patients with COPD and prolonged respiratory insufficiency admitted to our respiratory intensive care unit from 1976 to 1980 for acute respiratory failure. All subjects underwent intermittent negative pressure ventilation by means of an iron lung to overcome the acute episode. Twelve patients died during hospitalization, six were lost after discharge, while 87 were successfully weaned and were included in a follow-up lasting five years. All relapses of ARF were treated by INPV. The survival rates after one and five years were 82 percent and 37 percent, respectively and were significantly influenced by factors such as age, chronic cor pulmonale, FEV1/VC, PaCO2 on admission. The survival rate observed in our patients was better than that reported previously by other authors in COPD patients with ARF submitted to mechanical ventilation after intubation. These results suggest that INPV can improve survival in this category of patients, but a controlled clinical trial will be needed to address this issue.

Acute Disease↗
PubMed1992

External stabilization of flail chest using continuous negative extrathoracic pressure.

On rare occasions after total sternectomy, patients develop persistent flail chest deformities requiring long-term mechanical respiratory assistance. We report the use of a temporary external chest shell to deliver constant negative extrathoracic pressure (CNEP) to a long-term ventilated patient with flail chest. The patient's anterior thoracic cage stabilized, and significant improvement in pulmonary function was observed. With these data in hand, an operation was done to permanently stabilize the anterior chest wall by bone grafting.

Aged↗
PubMed1992

Sleep-disordered breathing in patients with Duchenne muscular dystrophy using negative pressure ventilators.

We studied the occurrence of nocturnal disordered breathing events and O2 desaturations in 12 patients with late-stage Duchenne muscular dystrophy (DMD) using negative pressure ventilators. We also assessed the effects of O2 supplementation and nasal continuous positive airway pressure (CPAP) on disordered breathing events in selected patients and examined sleep quality in a small subgroup. Average age was 23 + 2 years and FVC was 293 + 33 ml. Eleven of the 12 patients had more than five disordered breathing events per hour during nocturnal monitoring, and the lowest O2 saturation was < 85 percent in nine patients. Nasal O2 (2 L/min) during negative pressure ventilation in four patients did not alter the frequency of disordered breathing events, prolonged the mean and maximum durations of events, and failed to eliminate severe O2 desaturations in two patients. Nasal CPAP was used in two patients during negative pressure ventilation and completely eliminated disordered breathing events in both. Overnight polysomnography during negative pressure ventilation in three patients demonstrated frequent awakenings that fell in frequency following elective tracheostomy in two patients and use of nasal CPAP in one. We conclude that negative pressure ventilation in patients with late-stage DMD is associated with frequent disordered breathing events and severe O2 desaturations in many patients. Concomitant use of O2 supplementation may prolong the events, but a switch to positive pressure ventilation or addition of nasal CPAP is effective therapy.

Adolescent↗
PubMed1991

Suppression of ventilatory muscle activity in healthy subjects and COPD patients with negative pressure ventilation.

We evaluated the ability of NPV to suppress EMGd and EMGint in seven patients with severe COPD and five normal subjects. Subjects were studied either without (A) or with mouthpiece and nose clip (B). Electromyographic suppression was assessed comparing EMG activity during NPV with the control activity without a mouthpiece and prior to the initiation of the NPV run. In normal subjects, in A, NPV resulted in a partial suppression of EMGd; in B, prior to NPV, EMGd rose compared with A prior to NPV. In patients, in A, NPV resulted in a suppression of both EMGd and EMGint. In B, prior to NPV, both EMGd and EMGint rose compared with A prior to NPV. Thus, it seems that NPV is able to produce a consistent reduction in inspiratory muscle EMG activity. This variable NPV ability would have to be assessed for better selection criteria for patient candidates in a rehabilitation program.

Adult↗
PubMed1992

[A case of primary alveolar hypoventilation syndrome with a good response to nocturnal low-flow oxygen inhalation and negative pressure ventilation].

A 34-year-old female was admitted on June 25, 1990, for the evaluation of alveolar hypoventilation which worsened after her second delivery. She showed impairment of both hypercapnic and hypoxic ventilatory responses, and marked desaturation due to hypopnea and apnea during sleep. Although administration of methylxanthine and medroxyprogesterone was not very effective, after treatment with low flow oxygen, there was a marked decrease in the frequency and duration of desaturation during sleep and improvement of arterial daytime blood gases, which suggested the existence of hypoxic ventilatory depression in the pathophysiology of her nocturnal desaturation. Furthermore, the use of a negative pressure ventilator for 3 hours in the daytime for 10 days resulted in marked improvement of symptoms, arterial blood gases, respiratory muscle strength, and the frequency and duration of sleep desaturation. These findings suggest that both low flow oxygen therapy during sleep, and daytime negative pressure ventilation may be beneficial in patients with primary alveolar hypoventilation and central sleep apnea syndrome.

Adult↗
PubMed1992

[Intermittent negative pressure ventilation in patients with chronic air flow limitation: criteria for selection of patients].

To determine clinical and functional predictive criteria for use of intermittent negative pressure ventilation we evaluated 9 patients with severe chronic air flow limitation. Arterial blood gases, lung volumes, maximal inspiratory pressures and transdiaphragmatic pressure during quiet breathing were measured. patients were then ventilated once or twice a week for 3 to 10 weeks and improvement was evaluated through changes in quality of life, dyspnea, PaO2, PaCO2 and maximal inspiratory mouth pressure (PRMAX). Result was considered good when 4 or more of these indices improved. 5 patients benefitted from intermittent negative pressure ventilation. Compared to non responders, patients who improved had significantly lower PRMAX (39.4 +/- 11.6 VS 73.5 +/- 13.8 CMh20, p < 0.025), and higher percentage of their maximal inspiratory pressure during quiet breathing (31.2 +/- 7 vs 12.2 +/- 5%, p < 0.025>). Other indices were not different between groups. We conclude that a severe impairment of inspiratory muscle function characterizes patients with chronic air flow limitation who may benefit from intermittent negative pressure ventilation.

Adult↗
PubMed1992

[Dyspnea and rib cage distortion in postural changes].

We studied the topographical ventilatory motion and electrical muscle activity (EMG) of intercostal muscle within the rib cage for the patients complaining dyspnea produced mostly by their postural changes. There were inappropriateness between the rib cage motion and EMG and this inappropriateness was closely related to a sensation of dyspnea. We could relieve partly dyspnea by applying the negative pressure ventilator, because of prevention of a distortion of rib cage. Based on these clinical observation, we concluded that one of mechanism to sense dyspnea was the inappropriateness between motion and electrical muscle activity within the rib cage.

Dyspnea↗
PubMed1992

[Short-term effects of respiration with external negative ventilation --shield-type respirator-- on the pulmonary function in COPD].

With the objective to test the effect of intermittent and short term rest in respiratory muscles in patients with COPD and maintained hypercapnia we have studied 34 patients in a stable condition: 23 were part of the study group (Group I) and 11 were the control group (Group II). After a complete functional basal study, patients in Group I were treated with intermittent rest of their respiratory muscles, through a negative pressure external respirator--shield type--during three consecutive days. We got, in this study group, a significative improvement in the maximum inspiratory pressure measured at residual volume (PI max RV), which went from 66.6 +/- 15.9 to 71.2 +/- 15.2 (p < 0.005), as well as a lowering, also significative, of partial pressure of CO2 in arterial blood (PaCO2) and in expired air (EFCO2), which went from 55.2 +/- 7.2 to 52.3 +/- 3 (p < 0.0002) and 3.3 +/- 0.5 to 3.1 +/- 0.5 (p < 0.01), respectively. Maximum inspiratory pressure measured to functional residual capacity (PI max FRC) experienced an increase in the limit of statistical signification. Rest of the parameters did not significantly change. These results back the hypothesis that in stabilized COPD with CO2 retention, a chronic fatigue of respiratory muscles could exist, and that intermittent rest of these muscles could mean an hypercapnia diminution, due to the improvement in the function of respiratory muscles.

Adult↗
PubMed1992

Reversal of negative pressure ventilation-induced lower esophageal sphincter dysfunction with metoclopramide.

We have previously demonstrated that lower esophageal sphincter (LES) dysfunction is induced in healthy volunteers placed in negative pressure body ventilators. This is important, because regurgitation of gastric contents and peptic esophagitis are frequent complications of the use of such ventilators. The present study was conducted to determine whether LES dysfunction during the use of these ventilators also occurs in patients with chronic respiratory failure, and whether this dysfunction can be pharmacologically reversed. Seven patients with documented chronic respiratory failure due to COPD were studied. After an overnight fast, esophageal, LES, and gastric pressures were simultaneously recorded in the unassisted state and during mechanically assisted ventilation, after which 10 mg iv metoclopramide were administered to each patient, and pressure recordings were continued for 1 h more. In all seven patients, baseline LES pressures were in the normal range. During the inspiratory cycle of mechanical ventilation, five of the seven patients demonstrated a significant reduction in LES pressure, whereas it was unchanged in the other two. Within 15 min of metoclopramide administration, there was an increase in LES pressure to baseline levels in the five patients in which a significant decrease in LES pressure had occurred. Metoclopramide did not have any effect on the LES pressure of the other two patients. Thus, we conclude that in patients with chronic respiratory failure, as in normals, there is a subset of individuals in whom negative pressure mechanical ventilatory assistance induces dysfunction of the LES, and that this dysfunction is reversible with metoclopramide.

Diaphragm↗
PubMed1991

[The effect of continuous peri-thoracic negative pressure on nocturnal desaturation of chronic obstructive bronchopneumopathies].

The fall of functional residual capacity (FRC) in the genesis of nocturnal desaturation in chronic airflow obstruction (COPD) continues to be discussed. This hypothesis is being tested by applying a negative continuous thoracic pressure using a cuirass/poncho attached to a pump for one night (night II) after a control night with a cuirass/poncho at atmospheric pressure (night 1). Seven subjects with a mean age of 61 +/- 9, with a mean weight of 108 +/- 21% of their ideal weight, who were suffering from severe airflow obstruction with a mean forced expired volume (FEV1: 39 +/- 20% th., FEV1/FVC: 35 +/- 9%, PaO2: 60 +/- 3 mmHg, PaCO2: 42 +/- 4 mmHg). These seven subjects had two polysomnographies on the two successive nights. During night II, the FRC was increased by 0.33 +/- 0.6 L by applying a continuous negative thoracic pressure of 10 +/- 1 cm of water. A significant decrease in the sleep time was noted (248 +/- 86 min vs 316 +/- 74 min, p less than 0.02) also the efficacy of sleep (54 +/- 9% vs 71 +/- 15% vm p less than 0.02). There was no difference between the two nights as regards the distribution of the sleep stages. In 2 subjects, the hypopnoea-apnoea index passed from 0 to 11 and from 4 to 22 respectively. The principal result was the absence of any significant difference in mean nocturnal oxygen saturation between the two nights.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1991

Nocturnal negative pressure ventilation.

In this study, 25 patients between the ages of 12 and 24 years who had neuromuscular diseases, a vital capacity less than 50 percent of predicted, and a history suggestive of nocturnal hypoventilation were observed with overnight monitoring of end-tidal CO2 (EtCO2) and O2 saturation (SaO2). Those patients with a strong clinical history and evidence of nocturnal hypoventilation (increased EtCO2 of 50 to 70 torr and decreased SaO2 [less than 90 percent]) (10 patients) were placed on nocturnal negative pressure ventilation (NNPV). Admission, treatment, and posttreatment arterial blood gases were analyzed by paired statistical "t" tests. Comparison of mean PaO2 values obtained on admission with those obtained during treatment revealed a greater than 97.5 percent confidence (p = 0.025; n = 7). Mean PaO2 values obtained after treatment (off negative pressure ventilation [NPV], awake during daytime) were 65.9 +/- 18.2 mmHg and 79.0 + 14.5 mmHg, respectively (p = 0.005; n = 6). Comparison of post-treatment PaO2 values as a percentage of admission (pretest) values showed a significant change at the 0.5 percent level with an applied Wilcoxan Signed-ranks Matched-pairs Test. The mean PaCO2 values obtained upon admission and those obtained during treatment were 53.7 +/- 15.1 mmHg and 48.1 +/- 14.2 mmHg, respectively (p = 0.05; n = 7), and comparison mean PaCO2 values obtained upon admission and after treatment were 57.9 +/- 16.0 mmHg and 51.2 +/- 7.0 mmHg, respectively (p = 0.1; n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Respiratory flow and chest wall motion during negative extrathoracic pressure ventilation in human volunteers].

Respiratory flow and chest wall motion during negative extrathoracic pressure ventilation (NETPV) were compared with those during spontaneous breathing in 8 healthy male volunteers. Chest wall motion was evaluated by separate measurement of the changes in the cross sectional area of rib cage and abdomen, using respiratory inductive plethysmograph. During NETPV, expiratory flow was characterized by a large peak and a rapid decline at the early expiratory phase. NETPV increased the relative contribution of rib cage motion to tidal ventilation, and induced the abdominal paradoxical movements at inspiration in two volunteers. These results indicate that NETPV augments rib cage motion rather than abdominal motion, and this altered mechanics of chest wall may change intrapulmonary distribution of inspired gas.

Adult↗
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↗