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Biomedical subjects

G Villella

Publications and source records attributed to G Villella.

6 recordsLinked to original sources
PubMed2001

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.

Acute Disease↗
PubMed2000

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.

Adult↗
PubMed1998

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.

Acute Disease↗
PubMed1997

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.

Acute Disease↗
PubMed1996

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.

Contraindications↗