Ciro Rampulla

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)

Breathing pattern, ventilatory drive and respiratory muscle strength in patients with chronic heart failure

The purpose of this study was to evaluate whether chronic heart failure (CHF) may induce changes in breathing pattern and ventilatory neural drive. We studied 45 male inpatients with CHF, (25 patients in NYHA class II, 20 in class III) and 22 sex-matched post myocardial infarction patients without left ventricular dysfunction who served as controls. CHF patients underwent right heart catheterization and assessment of cardiac output by thermodilution technique. Patients and controls underwent evaluation of left ventricular ejection fraction by 2D echocardiography, spirometry, diffusion capacity, blood gases, breathing pattern, mouth occlusion pressure and respiratory muscle strength determination. Results of CHF patients were compared to controls and evaluated for differences according to the degree in severity of functional impairment. CHF patients showed a slight reduction in lung volumes and in diffusion capacity. In CHF neural drive, as assessed by mouth occlusion pressure (P0.1), was significantly increased in comparison to controls (P0.1 = 1.86 (0.7) and 1.4 (0.6) cmH2O in CHF and controls respectively). Analysis of breathing pattern showed only a slight yet significant increase in respiratory frequency while respiratory muscle strength, as assessed by measurement of maximal inspiratory and expiratory pressures (MIP and MEP respectively) was slightly reduced (MIP = 79(27) and 104(28); MEP = 111(32) and 142(33) cmH2O respectively). Observed changes were more relevant in patients with advanced NYHA functional classes whereas no relationship among indices of cardiac and respiratory function was found. We conclude that chronic heart failure induces changes in neural ventilatory drive and respiratory muscle strength related to the severity of the disease.

Recruitment of some respiratory muscles during three maximal inspiratory manoeuvres.

BACKGROUND--A study was undertaken to determine the level of recruitment of the muscles used in the generation of respiratory muscle force, and to ascertain whether maximal diaphragmatic force and maximal inspiratory muscle force need to be measured by separate tests. The level of activity of three inspiratory muscles and one expiratory muscle during three maximal respiratory manoeuvres was studied: (1) maximal inspiration against a closed airway (Muller manoeuvre or maximal inspiratory pressure (MIP)); (2) maximal inspired manoeuvre followed by a maximal expiratory effort (combined manoeuvre); and (3) maximal inspiratory sniff through the nose (sniff manoeuvre). METHODS--All the manoeuvres were performed from functional residual capacity. The gastric (PGA) and oesophageal (POES) pressures and their difference, transdiaphragmatic pressure (PDI), and the integrated EMG activity of the diaphragm (EDI), the sternomastoid (ESTR), the intercostal parasternals (ERIC), and the rectus abdominis muscles (ERA) were recorded. RESULTS--Mean (SD) PDI values for the Muller, combined, and sniff manoeuvres were: 127.6 (19.4), 162.7 (22.2), and 136.6 (24.8) cm H2O, respectively. The pattern of rib cage muscle recruitment (POES/PDI) was similar for the Muller and sniff manoeuvres (88% and 80% respectively), and was 58% in the combined manoeuvre, confirming data previously reported in the literature. Peak EDI amplitude was greater during the sniff manoeuvre in all subjects (100%) than during the combined (88.1%) and Muller (61.1%) manoeuvres. ESTR and EIC were more active in the Muller and the sniff manoeuvres. The contribution of the expiratory muscle (ERA) to the three manoeuvres was 100% in the combined, 26.1% for the sniff, and 11.5% for the Muller manoeuvre. CONCLUSIONS--Each of these three manoeuvres results in different mechanisms of inspiratory and expiratory muscle activation and the intrathoracic and intra-abdominal pressures generated are a reflection of the interaction between the various muscle groups. The Muller and sniff manoeuvres reflect mainly the force of the inspiratory muscles and the combined manoeuvre that of the diaphragm.

Intermediate respiratory intensive care units in Europe: a European perspective

In the early 1950s an outbreak of poliomyelitis in Scandinavia highlighted for the first time the need for hospital units specialised in treating episodes of acute respiratory failure. The first intensive care units (ICUs), at that time utilising non-invasive techniques such as tank ventilators, were therefore built in Northern Europe. Later on positive pressure ventilation via an endotracheal tube or a tracheotomy became common and the modalities of non-invasive ventilation were progressively abandoned.1 Insertion of an endotracheal tube is usually performed after sedation and paralysis of the patient, and for this reason for many years mechanical ventilation was the exclusive field of anaesthetists so that in many European countries ICUs are still run mainly by anaesthetists rather than “organ specialists”. This clinical and management background has also conditioned respiratory medicine in Europe, and only a few European countries include specific training in emergency medicine and mechanical ventilation as part of the programme of the specialisation in respiratory medicine.2 This is not the case in North America where intensive care medicine has been closely linked to respiratory medicine for many years. In the middle of the 1960s, following the pioneering experience of Dr Petty,3 a growing number of specialised respiratory intensive care units (RICUs) started to spread all over the USA alongside, and not in competition with, “general” ICUs.4 The RICUs were designed to treat acute or acute-on-chronic respiratory failure due to any pulmonary disease with monitoring systems equal to those of the ICUs. These units necessitated a specialised environment and personnel, with increasing costs, so that in the 1980s a new class of “step down” or “intermediate” critical care units, the so-called non-invasive respiratory care units (NRCU) or high dependency units (HDU)5 were developed as a less costly option for patients receiving long term mechanical …

Haemodynamic effects of pressure support and PEEP ventilation by nasal route in patients with stable chronic obstructive pulmonary disease.

BACKGROUND--Intermittent positive pressure ventilation applied through a nasal mask has been shown to be useful in the treatment of chronic respiratory insufficiency. Pressure support ventilation is an assisted mode of ventilation which is being increasingly used. Invasive ventilation with intermittent positive pressure, with or without positive end expiratory pressure (PEEP), has been found to affect venous return and cardiac output. This study evaluated the acute haemodynamic support ventilation by nasal mask, with and without the application of PEEP, in patients with severe stable chronic obstructive pulmonary disease and hypercapnia. METHODS--Nine patients with severe stable chronic obstructive pulmonary disease performed sessions lasting 10 minutes each of pressure support ventilation by nasal mask while undergoing right heart catheterisation for clinical evaluation. In random order, four sessions of nasal pressure support ventilation were applied consisting of: (1) peak inspiratory pressure (PIP) 10 cm H2O, PEEP 0 cm H2O; (2) PIP 10 cm H2O, PEEP 5 cm H2O; (3) PIP 20 cm H2O, PEEP 0 cm H2O; (4) PIP 20 cm H2O, PEEP 5 cm H2O. RESULTS--Significant increases in arterial oxygen tension (Pao2) and saturation (Sao2) and significant reductions in arterial carbon dioxide tension (PaCO2) and changes in pH were observed with a PIP of 20 cm H2O. Statistical analysis showed that the addition of 5 cm H2O PEEP did not further improve arterial blood gas tensions. Comparison of baseline values with measurements performed after 10 minutes of each session of ventilation showed that all modes of ventilation except PIP 10 cm H2O without PEEP induced a small but significant increase in pulmonary capillary wedge pressure. In comparison with baseline values, a significant decrease in cardiac output and oxygen delivery was induced only by the addition of PEEP to both levels of PIP. CONCLUSIONS--In patients with severe stable chronic obstructive pulmonary disease and hypercapnia, pressure support ventilation with the addition of PEEP delivered by nasal mask may have short term acute haemodynamic effects in reducing oxygen delivery in spite of adequate levels of SaO2.

Obstructive sleep apnoea syndrome : is the half-night polysomnography an adequate method for evaluating sleep profile and respiratory events?

Recently, to reduce the costs of polysomnography, split-night studies have been introduced into routine practice: the first part of the night is used to make the diagnosis of obstructive sleep apnoea syndrome (OSAS) and the second part to achieve an appropriate level of continuous positive airway pressure. Since this split-night protocol has not yet been validated by the comparison of polysomnographic pictures obtained in the first and second parts of the night, the aim of this study was to evaluate sleep profile and respiratory disturbances in the first part (PSG1) and second (PSG2) portion of a standard full-night polysomnographic examination (PSGtot) in a group of OSAS patients. Twenty nine consecutive OSAS patients, aged 54+/-10 yrs; body mass index (BMI) 40+/-6 kg x m(-2) (mean+/-SD values), were studied by separate analyses of PSG1, PSG2 and PSGtot. PSG1 was found to have a low sensitivity value (66%). A significant difference was found between apnoea-hypopnoea indices (AHI) recorded in PSG1, PSG2 and PSGtot (mean+/-SD, AHI1 33+/-27, AHI2 45+/-28, AHItot 40+/-25 events x h(-1), respectively; p<0.01). A strong correlation was observed between AHItot and AHI1 (r=0.89) and between AHItot and AHI2 (r=0.92), but a weaker correlation between AHI1 and AHI2 (r=0.66). These correlations became weaker when patients were subdivided into two different classes on the basis of disease severity. PSG1 was representative of PSGtot and similar to PSG2 only in those patients with rapid eye movement (REM) phase sleep in the first part of the night. We conclude that split-night protocols are not appropriate for evaluating sleep-disordered breathing in obstructive sleep apnoea syndrome patients when rapid eye movement phase sleep does not occur in the first part of the night.

Epidemiological diagnosis of asthma: methodological considerations of prevalence evaluation.

Within an epidemiological survey on Chronic Obstructive Pulmonary Disease, before reporting data on the prevalence of bronchial asthma we checked the group of subjects defined as ≪ pathological ≫ by means of a suitable questionnaire and a group of ≪ normals ≫ as a control.We evaluated the sensitivity and specificity of the questionnaire, in comparison with a clinical evaluation made by two physicians and controlled the relationship among their results, non-specific bronchial hyperreactivity and skin tests. In particular the correspondence between diagnosis made by physicians from a clinical evaluation and that obtained by questionnaire was not satisfactory.We suggest the importance of employing physicians for an epidemiological approach to asthma, in absence of a valid objective criterion.