Telemonitoring in chronic ventilatory failure: a new model of survellaince, a pilot study.

BACKGROUND AND AIM: The 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. METHODS: A 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. RESULTS: The 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). CONCLUSION: This pilot study showed that the telemonitoring system employed was feasible and effective in more compliant patients who claimed a high rate of satisfaction.

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.

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)

Effect of assist negative pressure ventilation by microprocessor based iron lung on breathing effort.

BACKGROUND: The lack of patient triggering capability during negative pressure ventilation (NPV) may contribute to poor patient synchrony and induction of upper airway collapse. This study was undertaken to evaluate the performance of a microprocessor based iron lung capable of thermistor triggering. METHODS: The effects of NPV with thermistor triggering were studied in four normal subjects and six patients with an acute exacerbation of chronic obstructive pulmonary disease (COPD) by measuring: (1) the time delay (TDtr) between the onset of inspiratory airflow and the start of assisted breathing; (2) the pressure-time product of the diaphragm (PTPdi); and (3) non-triggering inspiratory efforts (NonTrEf). In patients the effects of negative extrathoracic end expiratory pressure (NEEP) added to NPV were also evaluated. RESULTS: With increasing trigger sensitivity the mean (SE) TDtr ranged from 0.29 (0.02) s to 0.21 (0.01) s (mean difference 0.08 s, 95% CI 0.05 to 0.12) in normal subjects and from 0.30 (0.02) s to 0.21 (0.01) s (mean difference 0.09 s, 95% CI 0.06 to 0.12) in patients with COPD; NonTrEf ranged from 8.2 (1.8)% to 1.2 (0.1)% of the total breaths in normal subjects and from 11.8 (2.2)% to 2.5 (0.4)% in patients with COPD. Compared with spontaneous breathing, PTPdi decreased significantly with NPV both in normal subjects and in patients with COPD. NEEP added to NPV resulted in a significant decrease in dynamic intrinsic PEEP, diaphragm effort exerted in the pre-trigger phase, and NonTrEf. CONCLUSIONS: Microprocessor based iron lung capable of thermistor triggering was able to perform assist NPV with acceptable TDtr, significant unloading of the diaphragm, and a low rate of NonTrEf. NEEP added to NPV improved the synchrony between the patient and the ventilator.

Physiologic effects of negative pressure ventilation in acute exacerbation of 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.

Iron lung versus conventional mechanical ventilation in acute exacerbation of COPD.

The aim of this randomised study was to compare the effects of iron lung ventilation (ILV) with invasive mechanical ventilation (IMV) in patients with acute respiratory failure (ARF) due to exacerbation of chronic obstructive pulmonary disease. Forty-four patients with ARF were assigned either to ILV (22 patients) or IMV (22 patients). Primary end-points were the improvement in gas exchange and complications related to mechanical ventilation. On admission ILV and IMV groups did not differ in age, simplified acute physiology score II, arterial oxygen tension (Pa,O2)/inspiratory oxygen fraction (FI,O2), arterial carbon dioxide tension (Pa,CO2) and pH. Compared with baseline, ILV and IMV induced a similar and significant improvement in Pa,O2/FI,O2, Pa,CO2 and pH after 1 h of treatment and at discontinuation of mechanical ventilation. Major complications tended to be more frequent in patients treated with IMV than in those treated with ILV (27.3% versus 4.5%), whereas mortality rate was similar (27.3% versus 18.2%). The ventilator-free days and the length of hospital stay were significantly lower in the ILV than in the IMV group. This study suggests that iron lung ventilation is as effective as invasive mechanical ventilation in improving gas exchange in chronic obstructive pulmonary disease patients with acute respiratory failure, and is associated with a tendency towards a lower rate of major complications.