Ventilatory and respiratory muscle responses to hypercapnia in patients with paraplegia.

To evaluate ventilatory and respiratory muscle responses to hypercapnia in patients with paraplegia with paralysis of abdominal muscles, we studied seven patients with complete transection of the midthoracic cord (Th6-Th7) and six normal subjects. Minute ventilation (V E) and mean inspiratory flow responses to hypercapnia were similar in normal subjects and patients with paraplegia, but in the latter, at any given level of end-tidal CO(2) partial pressure (PET(CO(2))), tidal volume (VT) was reduced and frequency was increased. In normal subjects during hypercapnia, end-expiratory transpulmonary pressure (PL) and abdominal volume at end expiration decreased markedly, whereas end-expiratory volume of the rib cage (Vrc,E) remained constant, suggesting progressive recruitment of abdominal muscles. In patients with paraplegia compared to normal subjects the decrease in end-expiratory PL was reduced, and it was associated with a decrease in Vrc,E, suggesting recruitment of rib cage expiratory muscles. For a PET(CO(2)) of 70 mm Hg the estimated expiratory muscle contribution to VT was 10.3 and 28.4% (p < 0.02) in patients with paraplegia and normal subjects, respectively. We conclude that the V E-CO(2) relationship is preserved in patients with paraplegia with the development of a rapid and shallow pattern of breathing. This suggests that expiratory muscle paralysis elicits adaptation of the ventilatory control system similar to that observed in patients with generalized respiratory muscle weakness.

Negative pressure ventilation versus conventional mechanical ventilation in the treatment of acute respiratory failure in COPD patients.

This case-control study was aimed to evaluate the effectiveness of negative pressure ventilation (NPV) versus conventional mechanical ventilation (CMV) for the treatment of acute respiratory failure (ARF) in patients with chronic obstructive pulmonary disease (COPD) admitted to a respiratory intermediate intensive care unit (RIICU) and four general intensive care units (ICU). Twenty-six COPD patients in ARF admitted in 1994-95 to RIICU and treated with NPV (cases) were matched according to age (+/-5 yrs), sex, causes triggering ARF, Acute Physiology and Chronic Health Evaluation (APACHE) II score (+/- 5 points), pH (+/-0.05) and arterial carbon dioxide tension (Pa,CO2) on admission with 26 patients admitted to ICU and treated with CMV (controls). The primary end points of the study were inhospital death for both groups and the need for endotracheal intubation for cases. The secondary endpoints were length and complications of mechanical ventilation and length of hospital stay. The effectiveness of matching was 91%. Mortality rate was 23% for cases and 27% for controls (NS), five cases needed endotracheal intubation, four of whom subsequently died. The duration of ventilation in survivors was significantly lower in cases than in controls, with a median of 16 h (range 2-111) versus 96 h (range 12-336) (P<0.02), whereas the length of hospital stay was similar in the two groups, with a median of 12 days (range 2-47) for cases vs 12 days (range 3-43) (NS) for controls. No complications were observed in cases, whereas three controls developed infective complications. These results suggest that negative pressure ventilation is as efficacious as conventional mechanical ventilation for the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease and that it is associated with a shorter duration of ventilation and a similar length of hospital stay compared with conventional mechanical ventilation.

Negative pressure ventilation in COPD patients with acute on chronic respiratory failure.

Negative pressure ventilators act by exposing the surface of the chest wall to subatmospheric pressure during inspiration. During negative pressure ventilation (NPV), tidal volume is related to the peak of the inspiratory negative pressure and the pressure waveform generated by the ventilator pump; for the same peak of negative pressure a square wave produces a greater tidal volume than a half sine wave. Several uncontrolled studies suggest that NPV may have a potential therapeutic role in the treatment of acute on chronic respiratory failure in patients with chronic obstructive pulmonary disease (COPD), reducing the need for endotracheal intubation. Recently, NPV has been used with a good outcome as a first-line treatment in COPD patients with severe acute respiratory failure and hypoxic hypercapnic coma. The positive results of these reports need to be confirmed by further controlled studies before recommending the generalized use of NPV in COPD patients with acute respiratory failure as standard care.

Intermittent negative pressure ventilation in the treatment of hypoxic hypercapnic coma in chronic respiratory insufficiency.

BACKGROUND: In recent years non-invasive ventilatory techniques have been used successfully in the treatment of acute on chronic respiratory failure (ACRF), but careful selection of patients is essential and a comatose state may represent an exclusion criterion. The aim of this retrospective and uncontrolled study was to evaluate whether a non-invasive ventilatory technique such as the iron lung could also be used successfully in patients with hypoxic hypercapnic coma, thus widening the range for application of non-invasive ventilatory techniques. METHODS: A series of 150 consecutive patients with ACRF and hypoxic hypercapnic coma admitted to our respiratory intensive care unit were evaluated retrospectively. The most common underlying condition was chronic obstructive pulmonary disease (79%). On admission a severe hypoxaemia (Pao2 5.81 (3.01) kPa) and hypercapnia (Paco2 14.88 (2.78) kPa) associated with a decompensated acidosis (pH 7.13 (0.13)) were present, the Glasgow coma score ranged from 3 to 8, and the mean APACHE II score was 31.6 (5.3). All patients underwent intermittent negative pressure ventilation with the iron lung. The study end point was based on a dichotomous classification of treatment failure (defined as death or need for endotracheal intubation) versus therapeutic success. RESULTS: There were 45 treatment failures (30%) and 36 deaths (24%). Nine patients (6%) required intubation because of lack of airway control. The median total duration of ventilation was 27 hours per patient (range 2-274). The 105 successfully treated cases recovered consciousness after a median of four hours (range 1-90) of continuous ventilatory treatment and were discharged after 12.1 (9.0) days. CONCLUSIONS: These results show that, in patients with acute on chronic respiratory failure and hypoxic hypercapnic coma, the iron lung resulted in a high rate of success. As this study has the typical limitations of all retrospective and uncontrolled studies, the results need to be formally confirmed by controlled prospective studies. Confirmation of these results could widen the range of application of non-invasive ventilatory techniques.

Negative pressure ventilation in the treatment of acute respiratory failure: an old noninvasive technique reconsidered.

Noninvasive mechanical ventilatory techniques include the use of negative and positive pressure ventilators. Negative pressure ventilators, such as the "iron lung", support ventilation by exposing the surface of the chest wall to subatmospheric pressure during inspiration; whereas, expiration occurs when the pressure around the chest wall increases and becomes atmospheric or greater than atmospheric. In this review, after a description of the more advanced models of tank ventilators and the physiological effects of negative pressure ventilation (NPV), we summarize the recent application of this old technique in the treatment of acute respiratory failure (ARF). Several uncontrolled studies suggest that NPV may have a potential therapeutic role in the treatment of acute on chronic respiratory failure in patients with chronic obstructive pulmonary disease and restrictive thoracic disorders, reducing the need for endotracheal intubation. In the paediatric field, after substantial technical improvement, NPV has been successfully reintroduced for the treatment of ARF due to neonatal distress syndrome and bronchopulmonary dysplasia, and for the weaning from positive pressure ventilation in intubated patients. The positive results of these reports need to be formally confirmed by further prospective and controlled studies before recommending the generalized use of negative pressure ventilation in acute respiratory failure as a standard of care.

Breathing pattern and carbon dioxide retention in severe chronic obstructive pulmonary disease.

BACKGROUND: The factors leading to chronic hypercapnia and rapid shallow breathing in patients with severe chronic obstructive pulmonary disease (COPD) are not completely understood. In this study the interrelations between chronic carbon dioxide retention, breathing pattern, dyspnoea, and the pressure required for breathing relative to inspiratory muscle strength in stable COPD patients with severe airflow obstruction were studied. METHODS: Thirty patients with COPD in a clinically stable condition with forced expiratory volume in one second (FEV1) of < 1 litre were studied. In each patient the following parameters were assessed: (1) dyspnoea scale rating, (2) inspiratory muscle strength by measuring minimal pleural pressure (PPLmin), and (3) tidal volume (VT), flow, pleural pressure swing (PPLsw), total lung resistance (RL), dynamic lung elastance (ELdyn), and positive end expiratory alveolar pressure (PEEPi) during resting breathing. RESULTS: Arterial carbon dioxide tension (PaCO2) related directly to RL/PPLmin, and ELdyn/PPLmin, and inversely to VT and PPLmin. There was no relationship between PaCO2 and functional residual capacity (FRC), total lung capacity (TLC), or minute ventilation. PEEPi was similar in eucapnic and hypercapnic patients. Expressing PaCO2 as a combined function of VT and PPLmin (stepwise multiple regression analysis) explained 71% of the variance in PaCO2. Tidal volume was directly related to inspiratory time (TI), and TI was inversely related to the pressure required for breathing relative to inspiratory muscle strength (PPLsw, %PPLmin). There was an association between the severity of dyspnoea and both the increase in PPLsw (%PPLmin) and the shortening in TI. CONCLUSIONS: The results indicate that, in stable patients with COPD with severe airflow obstruction, hypercapnia is associated with shallow breathing and inspiratory muscle weakness, and rapid and shallow breathing appears to be linked to both a marked increase in the pressure required for breathing relative to inspiratory muscle strength and to the severity of the breathlessness.

Results of a questionnaire about nurse students' smoking habits and knowledges in an Italian teaching school of nursing.

Six-hundred and sixty-two nurse students (aged 25.2 +/- 4.11 years; 153 were males) answered a self-administered, anonymous questionnaire about smoking habits and knowledges in a large urban Teaching School of Nursing. The overall response rate was 88%. Current smokers were 336 (51%), former smokers 80 (12%). Nurse students claimed to know the dangers of tobacco and nurse training seemed to modify the preferential source of information about tobacco smoking towards medical fonts; however, only a quarter of nurse students considered medical smoking cessation approaches as useful for quitting and advised patients with tobacco-related diseases against smoking.

[Medico-legal aspects of chronic respiratory insufficiency under long-term oxygen inhalation therapy]. / Aspetti medico-legali dell'insufficienza respiratoria cronica con ossigeno terapia a lungo termine.

Ninety-one subjects affected by severe pulmonary insufficiency necessitating continuous treatment with oxygen were studied. The social and professional realities and their status within the national health service were determined. The results of the research, obtained through the use of the questionnaires, showed that the lives of these subjects are very much influenced by their pathology. Among the factors considered were necessity for home assistance, scarce or absence of autonomy and contact with the outside world and extremely reduced work capacity. Elevated public spending for assistance was analyzed in reference to public health insurance as regards each single subject and the type of lung dysfunction from which the subject suffered.

Iron lung treatment of acute on chronic respiratory failure: 16 yrs of experience.

Noninvasive ventilatory supports are gaining a prominent position among ventilatory techniques aimed to improve ventilation in patients with acute-on-chronic respiratory failure (ACRF). It has not yet been established whether these techniques can be considered as a preventive measure to avoid the need for endotracheal intubation, or are really another means to provide full ventilatory support. At our respiratory intensive care unit (RICU), the ventilatory treatment of ACRF has, for many years, been based on a conservative method, which relies on the use of a body ventilator (iron lung) providing intermittent negative pressure ventilation (INPV). From 1975 to 1991, we treated ACRF in 2,116 patients with chronic obstructive pulmonary disease (COPD) and 604 patients with restrictive thoracopulmonary disease (RTD). Two thousand and eleven patients (95%) underwent INPV. The mortality rate during hospitalization was 9.9% for the patients as a whole (10% and 8.9% for COPD and RTD patients, respectively). The mean length of stay in the RICU was 10.5 +/- 9.5 days. Furthermore, we report the results of our previous studies which investigated how the iron lung works, and how it affected the short- and long-term prognosis of COPD patients in ACRF. Finally, in 180 patients, we report the effects of INPV provided by iron lung on the treatment of ACRF with hypoxic hypercapnic coma (HHC). INPV resulted in a significant improvement of arterial blood gas values and pH, associated with a progressive recovery of the level of consciousness. Only 13 patients needed intubation and 41 (23%) died during hospitalization.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of intermittent negative pressure ventilation and long-term oxygen therapy for patients with COPD. A 4-year study.

We evaluated retrospectively the effect of long-term oxygen therapy (LTOT) on the prognosis of 35 patients with chronic obstructive pulmonary disease (COPD) and chronic respiratory insufficiency (group A) who were admitted to our respiratory intensive care unit from 1984 to 1986 for acute respiratory failure (ARF). All subjects were given intermittent negative pressure ventilation (INPV) by means of an iron lung to overcome the acute episode and were treated with LTOT after discharge. Forty-four patients with COPD who were treated with the same ventilatory method to overcome an acute disease exacerbation and who were not given LTOT were used as controls (group B). Both groups were followed up for at least 48 months. All relapses of ARF were treated by iron lung in both groups A and B. The overall survival was significantly better in group A than in group B (p = 0.05 by F test) indicating that LTOT improves survival in patients with COPD after a bout of ARF treated with mechanical ventilation. Therefore, combining INPV with LTOT for overcoming acute episodes and relapses of ARF appears to improve the prognosis of patients with COPD.

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.

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.

Respiratory function tests after mantle irradiation in patients with Hodgkin's disease.

Pulmonary function tests were performed in 43 patients with Hodgkin's disease before mantle irradiation and at 3, 6, 9, 12 and 15 or more months thereafter. Treatment was given with a telecobalt unit to a total dose of 36 to 42 Gy, the higher dose being reserved for cases with considerable mediastinal involvement. The functional parameters explored included static and dynamic lung volumes, gas exchanges, ventilatory efficiency, and airway resistance. Measured parameters were expressed as a percentage of the pre-treatment value (PTV) in the individual patient. In the whole group, only small variations in the functional indices were observed at 3 to 6 months after mantle irradiation. In patients with normal PTVs a greater variation in static and dynamic volumes was observed at 3 to 6 months after mantle irradiation, with complete recovery thereafter. The gas exchange parameters also showed a similar variation at 3 to 6 months but no recovery was demonstrated in the subsequent examinations. No changes in ventilatory efficiency and airway resistance were observed. In patients with abnormal PTVs, usually presenting large mediastinal adenopathy, all parameters improved after mantle irradiation, and the favourable effect of tumour regression was probably more important than the radiation damage on the pulmonary parenchyma.