Michele Vitacca

Non-invasive mechanical ventilation in acute respiratory failure due to chronic obstructive pulmonary disease: correlates for success.

BACKGROUND--Non-invasive mechanical ventilation is increasingly used in the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to identify simple parameters to predict the success of this technique. METHODS--Fifty nine episodes of acute respiratory failure in 47 patients with COPD treated with non-invasive mechanical ventilation were analysed, considering each one as successful (78%) or unsuccessful (22%) according to survival and to the need for endotracheal intubation. RESULTS--Pneumonia was the cause of acute respiratory failure in 38% of the unsuccessful episodes but only in 9% of the successful ones. Success with non-invasive mechanical ventilation was associated with less severely abnormal baseline clinical and functional parameters, and with less severe levels of acidosis assessed during an initial trial of non-invasive mechanical ventilation. CONCLUSIONS--The severity of the episode of acute respiratory failure as assessed by clinical and functional compromise, and the level of acidosis and hypercapnia during an initial trial of non-invasive mechanical ventilation, have an influence on the likelihood for success with non-invasive mechanical ventilation and may prove to be useful in deciding whether to continue with this treatment.

Non-invasive modalities of positive pressure ventilation improve the outcome of acute exacerbations in COLD patients.

Objective1) To compare the clinical usefulness of both non-invasive pressure support ventilation (NPSV) and non-invasive intermittent positive pressure ventilation in assist-control (A/C) mode (NIPPV) in chronic obstructive lung disease (COLD) patients with acute hypercapnic respiratory failure: 2) to compare retrospectively the usefulness of non-invasive mechanical ventilation (NMV) with standard medical therapy alone.DesignProspective randomized retrospective study.Setting2 Respiratory intermediate intensive units.Patients29 COLD patients (age: 62±8 years) with chronic respiratory failure were hospitalized in a department for rehabilitation during acute relapses of their disease. They were transferred to our intermediate intensive care unit (IICU) and submitted randomly to either NPSV (16 patients) or NIPPV (13 patients).Measurements and resultsBlood gas analysis, dynamic flows, clinical variables, success rate, time of ventilation, side effects and subjective score of compliance to therapy. Therapy was considered successful when endotracheal intubation was avoided and patients were returned to their condition prior to exacerbation. No statistically significant difference was found between NPSV and NIPPV in success rate (NPSV 87.5%; NIPPV 57%) or in time of ventilation (NPSV: 69±49; NIPPV: 57±49 h). A better compliance to non-invasive mechanical ventilation (NMV) was found in NPSV patients than in NIPPV patients; side effects were observed less frequently in the NPSV group. Comparison of the success rate of NMV was retrospectively performed with 35 control COLD patients with chronic respiratory insufficiency who had undergone an acute relapse of their disease in the 2 years preceding the institution of the IICU and had been treated with oxygen and medical therapy alone. Patients submitted to NMV showed a greater success rate than control (82 versus 54%) after a period of ventilation ranging from 4–216 h.ConclusionNon-invasive mechanical ventilation performed either by NPSV or NIPPV may improve the outcome of acute exacerbations of COLD, as compared to medical therapy alone. NPSV seems to be more acceptable to patients in comparison with NIPPV.

Tele-assistance in Chronic Respiratory Failure Patients: a Randomised Clinical Trial

Chronic respiratory patients requiring oxygen or home mechanical ventilation experience frequent exacerbations and hospitalisations with related costs. Strict monitoring and care have been recommended. The aim of the present study was to primarily evaluate reduction in hospitalisations and, secondly, exacerbations, general practitioner (GP) calls and related cost-effectiveness of tele-assistance (TA) for these patients. A total of 240 patients (101 with chronic obstructive pulmonary disease (COPD)) were randomised to two groups: an intervention group entered a 1-yr TA programme while controls received traditional care. No anthropometric and clinical differences were found between groups both in baseline and in mortality (18% for TA, 23% for controls). Compared with controls, the TA group experienced significantly fewer hospitalisations (-36%), urgent GP calls (-65%) and acute exacerbations (-71%). Only COPD patients, as a separate group, had fewer hospitalisations, emergency room admissions, urgent GP calls or exacerbations. Each patient referred to staff a mean±sd 36±25 times. After deduction of TA costs, the average overall cost for each patient was 33% less than that for usual care. In chronic respiratory failure patients on oxygen or home mechanical ventilation, a nurse-centred tele-assistance prevents hospitalisations while it is cost-effective. The chronic obstructive pulmonary disease group seems to have a greater advantage from tele-assistance.

Survival and prediction of successful ventilator weaning in COPD patients requiring mechanical ventilation for more than 21 days

We studied survival and failure or success of weaning from mechanical ventilation (MV) in 42 consecutive chronic obstructive pulmonary disease (COPD) patients requiring prolonged MV (more than 21 days) after an episode of acute respiratory failure requiring admission to our Intermediate Intensive Care Unit (IICU). Parameters including arterial blood gases, pulmonary function tests, respiratory muscle force, neuromuscular drive, and nutritional status were recorded during a phase of clinical stability, in order to identify the features related to survival and weaning. All the patients were submitted to a comprehensive rehabilitation programme. Successful weaning from MV was defined as complete respiratory autonomy for at least 48 h. Twenty three patients were successfully weaned from MV after an average period of 44 days (Group A), requiring no further MV during their stay in hospital, whilst the remaining 19 patients were not able to be disconnected from the ventilator (Group B). The discriminant analysis showed that weaning from MV was significantly associated with arterial carbon dioxide tension (PaCO2), neuromuscular drive (P0.1), maximal inspiratory pressure (MIP), arterial oxygen tension (PaO2), the ratio of respiratory frequency to tidal volume (f/VT) and the serum protein level. Other pulmonary function tests (forced expiratory volume in one second (FEV1), FEV1/forced vital capacity (FVC), anthropometric data, nutritional status, number of pulmonary exacerbations during MV and evidence of cor pulmonale, were similar in the two groups. The discriminant equation considering PaCO2 and MIP could separate the two groups with an accuracy of 84%. The overall survival at 2 yrs was 40%; in Group B it was significantly lower than in Group A (22 vs 68%). Most of the deaths occurred within the first 120 days after intubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive mechanical ventilation in severe chronic obstructive lung disease and acute respiratory failure: short-and long-term prognosis

ObjectiveTo evaluate the short-and long-term prognosis of patients with chronic obstructive lung disease (COLD) who had noninvasive mechanical ventilation (NMV) for acute respiratory failure (ARF).DesignRetrospective study.SettingTwo respiratory intermediate intensive care units.PatientsTwo groups of patients suffering from COLD and an ARF episode requiring mechanical ventilation. Group 1 (30 patients) was given NMV using face masks (aged 64±9 years; pH=7.28±0.05; PaCO2=83±18 mmHg; PaO2/FIO2=141±61). Group 2 (27 patients) was composed of control patients (aged=65±8 years; pH=7.26±0.05; PaCO2=75±17 mmHg; PaO2/FIO2=167±41) given MV using endotracheal intubation (EI) when clinical and functional conditions had further deteriorated because the medical therapy failed and NMV was not available at the time. Causes of ARF were in group 1 and 2 respectively: pneumonia in 8(27%) and 11(41%), acute exacerbation of COLD in 19 (63%) and 14 (52%) and pulmonary embolism in 3 (10%) and 2 (7%) patients.Measurements and resultsSuccess rate, mortality during stay in ICU (at 3 months and at 1 year), and the need for rehospitalization during the year following ARF were measured in this study. Group 1 showed a success rate of 74%, only 8/30 patients needing EI and conventional MV. In group 2, the weaning success was 74% (20/27 patients). The mortality for group 1 was 20% in IICU, 23% at 3 months and 30% at 1 year; and 26% for group 2 in ICU, 48% at 3 months and 63% at 1 year. Within each group 1-year mortality was greater (p<0.01) in patients with pneumonia. The number of new ICU admissions during the follow-up at 1 year was 0.12 versus 0.30 in groups 1 and 2 respectivelyp<0.05).ConclusionFor patients suffering from COLD who have undergone ARF, avoiding EI by early treatment with NMV is associated with better survival in comparison to patients bound to invasive MV. Pneumonia as a cause of ARF may worsen the prognosis in both groups of patients.

Effects of proportional assist ventilation on exercise tolerance in COPD patients with chronic hypercapnia

This study investigates the impact of proportional assist ventilation (PAV), a new mode of partial ventilatory support, on exercise tolerance and breathlessness in severe hypercapnic chronic obstructive pulmonary disease (COPD) patients. We also examined the effects of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV). On two consecutive days, 15 stable hypercapnic COPD patients underwent four endurance tests on a cycle ergometer at 80% of their maximal workrate, receiving, via a nasal mask in random order, either: 1) sham ventilation (CPAP: 1 cmH2O); 2) CPAP (6 cmH2O); 3) PSV (inspiratory pressure support: 12-16 cmH2O; expiratory positive airway pressure (EPAP): 1 cmH2O); or 4) PAV (8.6+/-3.6 cmH2O x L(-1) and 3+/-1.3 cmH2O x L(-1)x s(-1) of volume and flow assistance, respectively plus EPAP: 1 cmH2O). Oxygen supply was standardized to maintain an arterial oxygen saturation (Sa,O2) of 92-93%. Breathing pattern and minute ventilation (by respiratory inductive plethysmography), pulse oximetry, end tidal partial pressure of CO2, cardiac frequency and sensations of dyspnoea and leg discomfort (by Borg scale) were monitored. In comparison to sham ventilation, PAV, PSV and CPAP were able to increase the endurance time (from 7.2+/-4.4 to 12+/-5.6, 10+/-5.2 and 9.6+/-4.6 min, respectively) and to reduce dyspnoea and oxygen flow to the nasal mask. However, the greatest improvement was observed with PAV. We conclude that PAV delivered by nasal mask can im-prove exercise tolerance and dyspnoea in stable hypercapnic COPD patients and hence this mode of ventilatory support may be useful in respiratory rehabilitation programmes.

RESPIRATORY MUSCLE FUNCTION AND EXERCISE CAPACITY IN MULTIPLE SCLEROSIS

Patients with multiple sclerosis (MS) show a poor exercise tolerance. A reduction in respiratory muscle strength has also been reported. The purpose of this study was to evaluate whether reduction in exercise tolerance was related to respiratory muscle dysfunction. Twenty four multiple sclerosis patients (mean +/- SD age: 48 +/- 9 yrs, duration of illness 12.2 +/- 6 yrs, severity of illness as assessed by Expanded Disability Scale Score (EDSS) 5.3 +/- 2), underwent detailed evaluation of lung function tests, arterial blood gas analysis, respiratory muscle strength and endurance, and exercise test on an arm ergometer. Sixteen of the 24 patients were able to perform the exercise test (Group I), whilst the other eight were not (group II). Arterial blood gases and lung function tests were normal for both groups. Respiratory muscle strength as assessed both by maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) was significantly reduced (MIP 18-76 cmH2O; MEP 16-82 cmH2O) compared to predicted values. Inspiratory muscle endurance time was significantly reduced in Group II in comparison to Group I (247 +/- 148 vs 397 +/- 154 s, respectively). Both MIP and MEP were significantly related to inspiratory muscle endurance time. Endurance time, MIP and MEP were inversely significantly related to duration of illness, whilst only endurance time was significantly related to Expanded Disability Scale Score.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic effects of early administered mask proportional assist ventilation in patients with chronic obstructive pulmonary disease and acute respiratory failure.

Objective To evaluate the physiologic short-term effects of noninvasive proportional assist ventilation (PAV) in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD). Design Prospective, physiologic study. Setting Respiratory intermediate intensive care unit. Patients Seven patients with acute respiratory failure requiring noninvasive mechanical ventilation because of exacerbation of COPD. Interventions PAV was administered by nasal mask as first ventilatory intervention. The setting of PAV involved a procedure to adjust volume assist and flow assist to levels corresponding to patient comfort. Volume assist was also set by means of the “run-away” procedure. Continuous positive airway pressure (CPAP) amounting to 2 cm H2O was always set by the ventilator. This setting of assistance (PAV) was applied for 45 mins. Thereafter, CPAP was increased to 5 cm H2O (PAV + CPAP-5) without any change in the PAV setting and was administered for 20 mins. Oxygen was delivered through a port of the mask in the attempt to maintain a target Sao2 >90%. Measurements and Main Results Arterial blood gases, breathing pattern, and inspiratory effort were measured during unsupported breathing and at the end of PAV, and breathing pattern and inspiratory effort were measured after 20 mins of PAV + CPAP-5. PAV determined a significant increase in tidal volume and minute ventilation (+64% and +25% on average, respectively) with unchanged breathing frequency and a significant improvement in arterial blood gases (Pao2 with the same oxygen supply, from 65 ± 15 torr to 97 ± 36 torr; Paco2, from 80 ± 11 torr to 76 ± 13 torr; pH, from 7.30 ± 0.02 to 7.32 ± 0.03). The pressure-time product calculated over a period of 1 min (from 318 ± 87 to 205 ± 145 cm H2O·sec·min−1) was significantly reduced. PAV + CPAP-5 resulted in a further although not significant decrease in the pressure-time product calculated over a period of 1 min (to 183 ± 110 cm H2O·sec·min−1), without additional changes in the breathing pattern. Conclusions Noninvasive PAV is able to improve arterial blood gases while unloading inspiratory muscles in patients with acute exacerbation of COPD.

Effects of oxygen on autonomic nervous system dysfunction in patients with chronic obstructive pulmonary disease

Chronic hypoxaemia can play a pathological role in abnormalities of the autonomic nervous system (ANS). In patients with chronic obstructive pulmonary disease (COPD), chronic hypoxaemia is associated with increased mortality and only long-term oxygen therapy is able to improve their survival. Normoxaemic COPD patients have been shown to suffer from abnormalities in ANS function. The aims of this study were to evaluate ANS function in COPD patients with chronic hypercapnic respiratory insufficiency and to test whether oxygen supplementation could reverse any ANS dysfunction. Eleven stable COPD patients with chronic hypercapnic respiratory insufficiency underwent evaluation of ANS by analysis of variability in cardiac frequency at rest and during both vagal (controlled breathing) and sympathetic (tilting) stimuli breathing with and without oxygen supplementation. Thirteen male, healthy, nonsmoking volunteers served as controls. Evaluation of ANS in COPD patients during hypoxic conditions showed alterations both at rest and in response to vagal and sympathetic stimuli. Oxygen supply reversed hypoxaemia without significant changes in arterial carbon dioxide tension and, therefore, ANS alterations were corrected during sympathetic stimulus only. Breathing room air and oxygen, the resting low-frequency (LF) powers were 45+/-15 and 148+/-55 ms2 x Hz(-1), respectively, and controlled breathing LF were 107+/-41 and 141+/-113 ms2 x Hz(-1), respectively. In stable patients with chronic obstructive pulmonary disease with chronic respiratory insufficiency, hypoxaemia is associated with derangements in the autonomic nervous system which may be partially reversed by oxygen administration.

Long-term home care programmes may reduce hospital admissions in COPD with chronic hypercapnia

Long-term oxygen therapy (LTOT) has been shown to improve survival in chronic obstructive pulmonary disease (COPD) patients. The clinical effectiveness of long-term home mechanical ventilation (HMV) is still discussed, nevertheless both LTOT and HMV are often included in the home care programmes of these patients. To evaluate the effectiveness of home care programmes including either HMV or LTOT, 34 COPD patients were studied. They were admitted to either HMV (Group A: 12 males and 5 females, aged 62 +/- 5 yrs), or LTOT (Group B: 9 males and 8 females, aged 62 +/- 8 yrs). They were compared to a historical group (Group C: 19 males and 10 females, aged 67 +/- 16 yrs) performing only their usual standard LTOT during the same period. Spirometry, maximal inspiratory pressure and arterial blood gas values were assessed at baseline and at 6, 12 and 18 months of follow-up. Mortality rate and number of hospital and intensive care unit (ICU) admissions and days of hospitalization were also assessed. Four out of 17 (23%) patients in Group A, 3 out of 17 (18%) in Group B, and 5 out of 29 (17%) in Group C died within 18 months. Of the lung function tests, only maximal inspiratory pressure in Group A showed a significant increase in the 18th month (50 +/- 4 to 56 +/- 7 cmH2O; p<0.01). In comparison to 18 months prior to the study, hospital admissions (from 2.2 +/- 0.6 to 1.3 +/- 1.1 and from 2.0 +/- 0.7 to 1.0 +/- 0.9 for Group A and B, respectively; p<0.005 for both), and days of hospitalization (from 60 +/- 34 to 34 +/- 40 and from 55 +/- 23 to 18 +/- 20 days in Group A and B, respectively; p<0.005 for both) significantly decreased only in the two groups submitted to the home care programme. We conclude that home care programmes may be effective in the long-term treatment of chronically hypercapnic chronic obstructive pulmonary disease patients in reducing hospital admissions.