BACKGROUND AND AIMThe efficiency of tele-monitoring or tele-assistance in patients with severe chronic ventilatory failure in home mechanical ventilation (HMV) is still being investigated. Our aim was to test the feasibility of a model which consisted in: 1) once a week nocturnal telemonitoring, supervised by a doctor in charge in a Respiratory Intensive Care Unit, who also provided a telephone-counselling (24/7) on demand; 2) a scheduled visit every two months.METHODSA 2-year observational study was carried out on 16 patients ventilated for at least 1 year and for > or = 8 hours/day. Once a week patients underwent a nocturnal monitoring during HMV. The compliance was evaluated by regular transmission of data and regular follow-up, the level of satisfaction by a telephone-questionnaire.RESULTSThe adherence to the protocol study was good in 9/16 (56%) and poor in 7/16 (44%) patients. For each patient, the mean number of connections was 46.12 +/- 36.39 (70.7% of that expected), in those with good compliance it increased to 63.8 +/- 32.7 (114% of that expected). The median hours of connection was 343 (138-1019) and 89 (0-521) for patients with good and poor compliance respectively, p = 0.038. The mean scheduled visits for patient with good compliance was 6.9 +/- 4.14 (100% of that expected). Emergency visits were avoided in 62.5% of cases. The satisfaction score was higher in compliant versus non compliant patients (p = 0.019).CONCLUSIONThis pilot study showed that the telemonitoring system employed was feasible and effective in more compliant patients who claimed a high rate of satisfaction.

Objective. To investigate in clinical practice the role of non-invasive mechanical ventilation in the treatment of acute respiratory failure on chronic respiratory disorders. Design. An 18 months prospective cohort study. Setting. A specialised respiratory intensive care unit in a university-affiliated hospital. Patients. A total of 258 consecutive patients with acute respiratory failure on chronic respiratory disorders. Interventions. Criteria for starting non-invasive mechanical ventilation and for endotracheal intubation were predefined. Non-invasive mechanical ventilation was provided by positive pressure (NPPV) ventilators or iron lung (NPV). Results. The main characteristics of patients (70% with chronic obstructive pulmonary disease) on admission were (mean, SD or median, 25th-75th centiles): pH 7.29 (0.07), PaCO2 83 mm Hg (19), PaO2/FiO(2) 198 (77), APACHE II score 19 (15-24). Among the 258 patients, 200 (77%) were treated exclusively with non-invasive mechanical ventilation (40% with NPV, 23% with NPPV, and 14% with the sequential use of both), and 35 (14%) with invasive mechanical ventilation. In patients in whom NPV or NPPV failed, the sequential use of the alternative non-invasive ventilatory technique allowed a significant reduction in the failure of non-invasive mechanical ventilation (from 23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively). In patients as a whole, the hospital mortality (21%) was lower than that estimated by APACHE II score (28%). Conclusions. Using NPV and NPPV it was possible in clinical practice to avoid endotracheal intubation in the large majority of unselected patients with acute respiratory failure on chronic respiratory disorders needing ventilatory support. The sequential use of both modalities may increase further the effectiveness of non-invasive mechanical ventilation.

BACKGROUND:Cardiovascular complications are frequently observed in patients with chronic obstructive pulmonary disease (COPD) admitted to respiratory intensive care units and may affect the prognosis. The aims of this study were to evaluate a) the prevalence of cardiovascular complications in patients with COPD exacerbation admitted to respiratory intensive care units, b) which parameters detected at admission were predictive of cardiovascular complications, and c) the prognostic role of cardiovascular complications.METHODS:A series of 278 consecutive patients with COPD admitted to 11 Italian respiratory intensive care units between November 1997 and January 1998 has been retrospectively analyzed. All cardiovascular complications were recorded.RESULTS:One hundred and ten patients (39.6%) developed cardiovascular complications: congestive heart failure 49 (17.6%), arrhythmias 40 (14.4%), shock 13 (4.7%), and hypotension 11 (4%). Multivariate analysis showed that the APACHE II score, ECG abnormalities (supraventricular ectopic beats, right and/or left ventricular hypertrophy) and digoxin therapy were independent predictors of cardiovascular complications. The overall mortality was 9% being 4.7% in patients without and 15.5% in patients with cardiovascular complications (p = 0.0044). Multivariate analysis showed that the APACHE II score, respiratory rate, pneumonia and end-stage respiratory diseases were independent predictors of mortality.CONCLUSIONS:Cardiovascular complications occurred in many patients with COPD exacerbation admitted to respiratory intensive care units, and identify a subset of patients with higher mortality.

CONTENTSMethods . . . 1344Results 1345Geographical distribution and typeof units . . 1345Location . 1345Type of intervention according to differentlevels of care . . 1345Patient population and infectivecomplications. . 1346Discussion 1347Appendix: Items of the questionnaire. ........1348Name of institution . . 1348Hospital characteristics 1348Structural characteristics of the respiratoryintermediate care unit . 1348Technical equipment. . 1348Facilities . . . . . . 1349Staff . . 1349Characteristics of patients andintervention . . . . 1349Severe chronic obstructive pulmonary disease (COPD)patients, especially those with chronic respiratoryfailure, may frequently require periods of intensivetreatment, monitoring, nursing and, occasionally,ventilatory assistance in order to overcome acuteexacerbations. Ventilatory assistance is only rarelyprovided in the conventional ward [1], thereforeadmission to an intensive care unit (ICU) is oftenneeded [2]. ICU, however, are very precious and expen-sive resources where nursing costs represent a majorexpense [3]. Patients with acute on chronic respiratoryfailure may experience a prolonged stay in the ICUnot only because of the severity of their illness whichprecipitates the underlying acute respiratory failure(ARF) [2], but also because of ICU-related complica-tions [4]. For these reasons the treatment of acute onchronically ill patients in these areas creates ethical [5]and economic concerns [6, 7].It has been reported that y40% of the patientsadmitted to ICUs never received active intensive care,including mechanical ventilation [8–10]. Onlyy40% ofpatients with ARF due to pulmonary disease neededto be invasively ventilated [11, 12]. However, in somecountries, such as the UK, with a severe ICU bedshortage, the vast majority of ICU admissions requiremechanical ventilation.A recent Italian survey carried out on 99 ICUsshowed that COPD was the dominant underlyingchronic disease in patients admitted to the Italian ICU,and the need for cardiorespiratory monitoring was themost frequent indication for admission (31.2%) [13].These studies clearly indicate that in some centresthere is an overutilisation of ICU resources formonitoring purposes, and that acute on chronic res-piratory failure could be managed in many patientswithout invasive ventilation.Patients with chronic respiratory failure, especiallythose with underlying COPD, very often suffer from ahigh frequency of acute exacerbations, which, whenrequiring invasive mechanical ventilation, may beassociated with life-threatening complications [4].Furthermore, it has been reported that in COPDpatients with ARF the greater part of their ICU staywas devoted to weaning the patient from mechanicalventilation, and this weaning period accounted for59% of the total duration of mechanical ventilation [14].

In Europe there is an extreme variability among countries regarding the distribution and availability of resources. The percentage of health care costs dedicated to intensive care ranges from 2.5% in The Netherlands to 1% in the United Kingdom. The number of acute hospital beds allocated to intensive care ranges from 2.6% to 4.1% in the United Kingdom and Denmark, respectively. A strategy to deal with the high cost is to provide graded levels of care to critically ill patients. Respiratory intensive care units (RICUs) are specialized intermediate care units devoted to treating patients with acute or acute chronic respiratory failure. The distribution of RICUs in Europe is uneven; 68 units are present in seven countries, with the major distribution in Italy, Germany, and France. There are differently graded levels of care that are provided in these units: intensive care (12 units), intermediate care (42 units), and monitoring (14 units). The median number of beds is seven (range, 4 to 18) in the RICU, six (range, 2 to 11) in the intermediate care unit, and six (range, 2 to 23) in the monitoring units. Seventeen of the 68 units are independent wards, and 48 are inside other wards (83% in pneumology ward). The type of intervention varies according to the three levels of care. In the RICU, invasive mechanical ventilation is performed in most cases, whereas in the intermediate unit, invasive mechanical ventilation, noninvasive mechanical ventilation, and monitoring are performed in a similar percentage of cases. In the monitoring unit, most interventions are noninvasive mechanical ventilation and monitoring only.

Noninvasive mechanical ventilatory techniques include the use of negative and positive pressure ventilators. Negative pressure ventilators 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 equal to or greater than atmospheric pressure. In this article, a description of negative pressure ventilators and the physiologic effects of negative pressure ventilation (NPV) is given, and the application of this technique in the long-term treatment of chronic respiratory failure is summarized. Many studies, although uncontrolled, have shown that long-term treatment with NPV can improve respiratory muscle function, arterial blood gases, and survival in patients with neuromuscular and chest wall disorders. NPV devices, however, are more cumbersome and difficult to use than home positive pressure ventilators (PPVs) and tend to predispose to obstructive apnoeas during sleep. In the last several decades, NPV has been supplanted by mask PPV. In experienced hands, NPV remains a second viable option in patients with neuromuscular and chest wall disorders who, for technical or other reasons, cannot be offered mask PPV. There is no evidence, however, that long-term treatment with NPV can improve respiratory muscle function, exercise endurance, quality of life, and survival in patients with severe chronic obstructive pulmonary disease.

To assess the physiologic effects of continuous negative extrathoracic pressure (CNEP), negative pressure ventilation (NPV), and negative extrathoracic end-expiratory pressure (NEEP) added to NPV in patients with acute exacerbation of chronic obstructive pulmonary disease (COPD), we measured in seven patients ventilatory pattern, arterial blood gases, respiratory mechanics, and pressure- time product of the diaphragm (PTPdi) under four conditions: (1) spontaneous breathing (SB); (2) CNEP (-5 cm H(2)O); (3) NPV; (4) NPV plus NEEP. CNEP and NPV were provided by a microprocessor-based iron lung capable of thermistor-triggering. Compared with SB, CNEP improved slightly but significantly Pa(CO(2 ))and pH, and decreased PTPdi (388 +/- 59 versus 302 +/- 43 cm H(2)O. s, respectively, p < 0.05) and dynamic intrinsic positive end-expiratory pressure (PEEPi) (4.6 +/- 0.5 versus 2.1 +/- 0.3 cm H(2)O, respectively, p < 0.001). NPV increased minute ventilation (V E), improved arterial blood gases, and decreased PTPdi to 34% of value during SB (p < 0.001). NEEP added to NPV further slightly decreased PTPdi and improved patient-ventilator interaction by reducing dynamic PEEPi and nontriggering inspiratory efforts. We conclude that CNEP and NPV, provided by microprocessor-based iron lung, are able to improve ventilatory pattern and arterial blood gases, and to unload inspiratory muscles in patients with acute exacerbation of COPD.

Patients with traumatic transection of the lower segments of the cervical cord contract the clavicular portion of the pectoralis major during forced expiration and cough, and the rise in intrathoracic pressure resulting from this contraction produces dynamic airway compression in many patients. Because the abdominal muscles are paralyzed, however, there is paradoxical expansion of the abdomen, which may reduce the rise in intrathoracic pressure and the degree of airway collapse. To evaluate the magnitude of this effect, we measured expiratory flow rate (Vexp) and esophageal pressure (Pes) during a series of forced expiratory vital capacity maneuvers and constructed isovolume-pressure flow (IVPF) curves before and after abdominal strapping in eight C5-8 tetraplegic subjects. Strapping produced small and inconsistent changes in maximal Vexp and Pes and resulted in the development of small flow plateaus in only four patients. In tetraplegic subjects, abdominal strapping thus has small effects on forced expiration and is unlikely, therefore, to improve the efficiency of cough.

We studied the effects of head-to-foot acceleration (+Gz) on chest wall mechanics in five normal subjects seated in a human centrifuge. Results were compared with those previously obtained in the same subjects in microgravity during parabolic flights. In all subjects, end-expiratory abdominal pressure (Pga) and volume (Vab) increased with Gz. On average, end-expiratory Pga increased from 7.4 +/- 1.7 cmH2O at + 1 Gz to 14.9 +/- 2.8 cmH2O at + 3 Gz and end-expiratory Vab increased by 0.32 +/- 0.06 liter between + 1 and + 3 Gz. On the other hand, the abdominal contribution to tidal volume (Vab/VT) and abdominal compliance decreased from 34.7 +/- 5.9% and 52 +/- 6 ml/cmH2O at + 1 Gz to 29.3 +/- 5.1% and 26 +/- 4 ml/cmH2O at + 3 Gz, respectively. Changes in end-expiratory Pga were linear between 0 and + 3 Gz, but changes in end-expiratory Vab, Vab/VT, and abdominal compliance were greater in microgravity than in hypergravity. In contrast to weightlessness, which did not alter minute ventilation and tidal changes in Pga and transdiaphragmatic pressure, these variables increased with increasing Gz. These results indicate that, although changes in Gz have a linear effect on abdominal transmural pressure, hypergravity and weightlessness do not have symmetrical effects on chest wall mechanics.

Although all the well-recognized muscles of expiration are paralyzed after traumatic transection of the lower cervical cord, tetraplegic subjects can still empty their lungs actively by contracting the clavicular portion of the pectoralis major. It is not known, however, whether contraction of this muscle bundle may raise pleural pressure enough to cause dynamic compression of the intrathoracic airways, which is critical for the production of an effective cough. To investigate this question, we measured expiratory flow rate and esophageal pressure during a series of forced expiratory vital capacity (VC) maneuvers in twelve subjects with C5-8 traumatic tetraplegia and constructed isovolume-pressure flow (IVPF) curves. The curves were interpretable with certainty in nine patients. Three of them did not show any plateau of flow. On the other hand, six patients had clearcut plateaus of flow on all IVPF curves between 80-60 and 20% VC, suggesting they had dynamic airway compression. Videoendoscopic recordings in two patients confirmed trachea and main bronchi collapse during forced expiration and cough. We conclude, therefore, that contraction of the pectoralis major causes dynamic airway compression during expiratory efforts in a substantial proportion of tetraplegic subjects. Increasing the pressure-generating capacity of this muscle might thus improve the effectiveness of cough and reduce the prevalence of bronchopulmonary infections.

Bronchial mucosa inflammation is a hallmark of asthma. Epithelial damage due to inflammatory process may contribute to induce a pattern of rapid and shallow breathing (RSB). Probably due to its effects on inflammatory process, beclomethasone dipropionate (BDP) decreases bronchial hypersensitivity (BH), as assessed in terms of histamine concentration causing a 20 percent FEV1 decrease from saline solution (PC20FEV1); however, no data are available on the effect of BDP on RSB. We studied 32 asymptomatic asthmatic subjects with a severe to moderate levels of BH (PC20FEV1 0.01 to 1.7 mg/ml). After they were randomly assigned to one month of either BDP (2 mg daily, 17 patients) or placebo (15 patients), they inhaled progressively doubling concentrations of histamine phosphate by tidal breathing method. With histamine in seven BDP-treated and in five placebo-treated patients, decrease in FEV1 > or = 20 percent from saline solution was paralleled by a significant decrease in tidal volume (VT), inspiratory time (Ti), and expiratory time (Te), and increase in respiratory frequency (RF). In the remaining patients, histamine failed to change the breathing pattern. In the seven RSB patients, BDP resulted in a smaller VT decrease (p < 0.02) and a smaller RF increase (p < 0.02) with histamine. The five RSB placebo-treated patients were then given one month BDP (2 mg daily): inhaled BDP, but not placebo, resulted both in a significant increase in PC20FEV1 and modulation in histamine-induced changes in breathing pattern. We conclude that high doses of BDP seem to be able to modulate histamine-induced RSB, an effect that might be linked to reversal of airway inflammation.

Broxaterol, a new selective beta 2-agonist, has been shown to exert inotropic effects on both fresh and fatigued canine diaphragm. We evaluated the effect of broxaterol on the activation and force output of the respiratory muscles in patients with chronic obstructive pulmonary disease (COPD). We studied 9 patients with moderate to severe COPD. Each patient was infused with saline and Broxaterol (200 micrograms) in saline alternately. We measured lung volumes, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), breathing pattern, P0.1, respiratory muscle EMG (diaphragm, EMGd, and parasternal, EMGp) and P0.1/EMGd ratio. Measurements were made under control conditions and at 15, 30, 60, and 120 min after each infusion. Broxaterol, but not saline, resulted in a slight but significant increase in vital capacity (VC), forced expiratory volume in one second (FEV1) and MIP, and a decrease in functional residual capacity (FRC). Breathing pattern did not change, while EMG significantly decreased, and P0.1/EMGd significantly increased in 5 of the 9 patients after broxaterol. These data seem to indicate that by partially unloading the respiratory muscles, broxaterol results in decreased muscle activation (EMG). Increase in chest wall neuromuscular coupling (P0.1/EMGd) may also be observed.

We studied the effect of microgravity (0 Gz) on the anteroposterior diameters of the upper (URC-AP) and lower (LRC-AP) rib cage, the transverse diameter of the lower rib cage (LRC-TR), and the xiphipubic distance and on the electromyographic (EMG) activity of the scalene and parasternal intercostal muscles in five normal subjects breathing quietly in the seated posture. Gastric pressure was also recorded in four subjects. At 0 Gz, end-expiratory LRC-AP and xiphipubic distance increased but LRC-TR invariably decreased, as did end-expiratory gastric pressure. No consistent effect was observed on tidal LRC-TR and xiphipubic displacements, but tidal changes in URC-AP and LRC-AP were reduced. Although scalene and parasternal phasic inspiratory EMG activity tended to decrease at 0 Gz, both muscle groups demonstrated an increase in tonic activity. We conclude that during brief periods of weightlessness 1) the rib cage at end expiration is displaced in the cranial direction and adopts a more circular shape, 2) the tidal expansion of the ventral rib cage is reduced, particularly in its upper portion, and 3) the scalenes and parasternal intercostals generally show a decrease in phasic inspiratory EMG activity and an increase in tonic activity.

Subjects with traumatic tetraplegia use the pectoralis major to compress the upper rib cage and increase intrathoracic pressure during cough. It is not known, however, whether they also contact the diaphragm during the expiratory phase of cough, as normal subjects do. We have investigated the action of the diaphragm during single voluntary coughing efforts in subjects with complete transection of the lower cervical (n = 5) or midthoracic (n = 2) cord. All subjects showed at least one peak of transdiaphragmatic pressure during the expiratory phase of the effort, and simultaneous bursts of electrical activity were recorded from the diaphragm. Coughing also resulted in an outward (paradoxical) motion of the abdomen during the compressive phase. We conclude that antagonistic contraction of the diaphragm is present during the expiratory phase of cough in spinal cord-injured subjects with paralysis of the abdominal muscles; this contraction, therefore, does not occur in response to activation of these muscles. The present results also indicate that the cough-induced paradoxical expansion of the abdomen is due to contraction of the pectoralis major and not of the diaphragm.

To examine how anesthetized dogs compensate for the diaphragmatic shortening that occurs during head-up tilting, we measured the electroneurogram (ENG) of the C5 phrenic root and the electromyographic (EMG) activity of the parasternal intercostal and transversus abdominis muscles in eight spontaneously breathing animals during postural changes between supine (0°) and 80° head-up. Both steady state ENG and EMG activities and first breath responses to tilting from 80° head-up to supine were studied. These experiments have shown that: (1) anesthetized dogs respond to head-up tilting by increasing the neural drive to the costal diaphragm and parasternal intercostals; (2) this response, however, does not occur on the first breath and therefore cannot compensate for the immediate changes in diaphragmatic length; (3) the abdominal muscles, in contrast, show a first breath response to tilting and their activation is primarily responsible for the maintenance of tidal volume. Unlike in humans, increases in neural inspiratory drive in head-up anesthetized dogs are mediated by a chemoreceptive, rather than proprioceptive, feedback mechanism.