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S Nava

Publications and source records attributed to S Nava.

At least 37 records · Page 2Linked to original sources
PubMed2001

Salbutamol delivery during non-invasive mechanical ventilation in patients with chronic obstructive pulmonary disease: a randomized, controlled study.

OBJECTIVE: We investigated the clinical response to equivalent doses of salbutamol delivered, via metered dose inhaler (MDI) during non-invasive mechanical ventilation (NIMV-MDI), during spontaneous breathing using a spacer (MDI-Spacer), and also during intermittent positive pressure breathing (IPPB). SETTING: A respiratory intensive care unit. DESIGN: Prospective, randomized, and placebo-controlled study. PATIENTS: Eighteen stable patients with chronic obstructive pulmonary disease (mean FEV1=38.5+/-8.8% predicted). RESULTS: Overall salbutamol administration induced, compared to placebo, a significant improvement in FEV1, irrespective of the mode of administration (+7.9+/-7.1% or +108+/-91 ml for IPPB, +9.6+/-8.8% or 112+/-67 ml for MDI-NIMV (inspiratory pressure=14.3+/-1.8 cmH2O; expiratory pressure=none), and +10.8+/-11.4% or 119+/-114 ml for MDI-Spacer, respectively). DeltaFVC significantly increased from placebo only in MDI-NIMV (+214+/-182 ml P=0.02). A second set of experiments performed in eight patients to ascertain the possible effect of NIMV on pulmonary function tests, showed a significant improvement from baseline values in FVC both after the delivering of placebo or salbutamol via NIMV-MDI (+206+/-147 ml and 208+/-145, respectively). FEV1 significantly increased only after salbutamol. No changes in gas exchange were observed after bronchodilator delivery. CONCLUSIONS: We show that delivery of bronchodilators via MDI with a spacer chamber during NIMV is feasible and induces a significant bronchodilator effect compared to placebo, even though it may be slightly less effective than the classical delivery system (MDI-Spacer).

Administration, Inhalation↗
PubMed2001

Postoperative analgesia by combined continuous infusion and patient-controlled epidural analgesia (PCEA) following hip replacement: ropivacaine versus bupivacaine.

BACKGROUND: Ropivacaine is a new local anaesthetic, which compared to bupivacaine is less toxic and shows greater sensory and motor block dissociation. We hypothesised that treatment of postoperative pain with a combined regimen of continuous epidural infusion and Patient-Controlled Epidural Analgesia (PCEA) using ropivacaine could have given better results compared with those we had obtained using bupivacaine. METHODS: Patients undergoing total hip replacement were randomly assigned to two groups. They received epidural analgesia for postoperative pain treatment using ropivacaine, 2 mg x ml(-1) or bupivacaine 2 mg x ml(-1). Both drugs were administered as a constant infusion of 6 ml x h(-1) supplemented by PCEA bolus doses of 2 ml. Patients in both groups received morphine intravenously on demand from a patient-controlled analgesia (PCA) device. An independent observer recorded pain scores, intensity of motor block and morphine consumption at regular intervals during the first 24 h after surgery. RESULTS: Fifty-one patients were evaluated. Ropivacaine and bupivacaine, in similar amounts, provided similar results assessed as adequate to very good postoperative analgesia, whereas motor block was significantly more intense in patients treated with bupivacaine. CONCLUSIONS: Despite similar analgesic effects, epidural infusion of ropivacaine combined with PCEA provides higher patient satisfaction than equal doses of bupivacaine due to lack of motor block.

Aged↗
PubMed2001

Physiologic evaluation of 4 weeks of nocturnal nasal positive pressure ventilation in stable hypercapnic patients with chronic obstructive pulmonary disease.

BACKGROUND: The long-term daily use of noninvasive mechanical ventilation (NIMV) to treat chronic respiratory failure in chronic obstructive pulmonary disease (COPD) patients is not widely recommended, partly because of a lack of clear clinical results and partly because the physiological mechanisms by which the daily application of NIMV would be helpful in these patients have not yet been clarified. OBJECTIVES: We designed a physiological study in order to assess the effects of supervised long-term NIMV on gas exchange, respiratory muscle function, pulmonary mechanics and to ascertain the possible effect of the treatment in responders and nonresponders. METHODS: Fourteen consecutive inpatients with stable hypercapnic COPD (pH = 7.37 +/- 0.01; PaCO(2) = 56.73 +/- 6.48 mm Hg) underwent 4 weeks of nocturnal NIMV delivered with a bilevel ventilator 'physiologically' set to reduce tidal transdiaphragmatic pressure (Pdi) by at least 50% and the amount of dynamic intrinsic positive end-expiratory pressure by 70%. Various measurements were compared with those obtained in a control group of consecutive patients with comparable baseline characteristics who refused NIMV and underwent breathing exercises for the same period of time. RESULTS: By the end of the 4 weeks NIMV had induced a slight but significant (p < 0.01) reduction in resting PaCO(2) (53.78 +/- 5.64 mm Hg) associated with a decrease in the pressure time product of the diaphragm per minute (from 172 +/- 60 to 136 +/- 61 cm H(2)O/l/s; p < 0.05). This latter value was primarily due to a significant shortening of the inspiratory duty cycle, while Pdi and lung mechanics were not modified. Eight of the 13 NIMV-treated patients (1 dropped out for nonmedical reasons) had a clear reduction in PaCO(2) (>3 mm Hg or >5% from enrollment) and were classified as responders. The acute reduction in PaCO(2) during the first trial with NIMV resulted to be a strong index of the final response. The subgroup of responders had a significantly increased maximal Pdi (from 41 +/- 19 to 49 +/- 23 cm H(2)O, p < 0.05) and an enhanced ability of the ventilatory pump to clear CO(2) (9.7 +/- 3.4 vs. 7.2 +/- 2.9 cm H(2)O x s/min; p < 0.01). No significant changes were observed in the control group. CONCLUSIONS: These results suggest that in a remarkable and identifyable proportion of patients with stable hypercapnic COPD, nocturnal NIMV may decrease resting PaCO(2), reraising the role of chronically supporting the respiratory pump.

Aged↗
PubMed2001

Is it safe for patients with chronic hypercapnic respiratory failure undergoing home noninvasive ventilation to discontinue ventilation briefly?

STUDY OBJECTIVES: A brief discontinuation (< 1 week) of long-term ventilation may be necessary in patients who are not totally ventilator-dependent in cases of technical problems, intolerable nasal irritation, upper airway congestion, or travel. We examined the incidence, timing, and causes of possible clinical deterioration after a brief withdrawal of ventilation in patients with chronic respiratory failure (CRF) who were well-established on long-term noninvasive mechanical ventilation (NIMV). STUDY DESIGN: Prospective clinical study. PATIENTS: Eleven inpatients in clinically stable condition (COPD, 6 patients; and restrictive thoracic disease [RTD], 5 patients) who had severe CRF (PaCO(2), > 50 mm Hg) and had been receiving NIMV for (mean +/- SD) 19.3 +/- 5.3 months were enrolled. INTERVENTIONS AND MEASUREMENTS: Arterial blood gas (ABG) levels, maximal inspiratory pressure (PImax), breathing pattern, dyspnea rating, and life symptoms (measured by a questionnaire) were recorded daily after NIMV withdrawal for 6 days or until the patients showed clinical and/or ABG level deterioration. Pulmonary function tests were performed and neuromuscular drive was measured at the beginning and the end of the study. RESULTS: Five of the 11 patients (45.4%) [COPD, 3 patients; and RTD, 2 patients] were reconnected to a ventilator before the scheduled time because of ABG level deterioration. Despite these changes, none of the patients reported severe worsening of symptoms or other medical complications. The patients whose ABG levels worsened had statistically significant decreases in tidal volume and PImax, suggesting that the development of alveolar hypoventilation was related to respiratory muscle weakness. CONCLUSIONS: A brief discontinuation of NIMV in patients who were affected by chronic hypercapnic respiratory failure and were well-established on NIMV is associated with a relatively high incidence of ABG level worsening due to the development of alveolar hypoventilation. If NIMV must be briefly interrupted for clinical reasons, the patient should be monitored closely for abrupt worsening, and prompt technical intervention should be provided if a ventilator fails.

Adult↗
PubMed2001

Respiratory muscles in chronic obstructive pulmonary disease and asthma.

Chronic obstructive pulmonary disease (COPD) and asthma are characterized by airflow obstruction and significant increase of respiratory muscle workload, with concrete risk of ventilatory pump failure. Respiratory muscles, the main component of this pump, undergo structural and functional changes during the course of these diseases. Aim of the present paper is to analyze modifications of respiratory muscles in COPD and asthma. An analysis of the most important controlled clinical studies released during the past years was carried out. The patients suffered from chronic obstructive pulmonary disease and asthma. In COPD, respiratory muscles have to cope with an increased load, an intrinsic weakness and a mechanical disadvantage, especially in the diaphragmatic length-force relationship; in patients with acute asthma, the main features are a massive hyperinflation and a persistent inspiratory muscle activity during expiration. Modifications of respiratory muscles deserve great consideration not only for the complete comprehension of the underlying physiopathologic aspects of these diseases, but also for the optimal clinical management: a reduced pulmonary hyperinflation in COPD place the respiratory muscles in a better position of the force-length curve while great care must be payed to the metabolic and nutritional aspects. During asthmatic crisis respiratory muscles are subjected to a sort of intense training but anyway persistence of bronchospasm in most severe attacks can lead to exhaustion of the ventilatory pump and need of mechanical ventilatory support.

Asthma↗
PubMed2001

[Technical difficulties in epidural blocks and spinal bleeding complications].

The clinical cases of two patients with neurological complications following neuroaxial blocks are reported. The events took place in different institutions where thousands of central blocks were yearly performed. In both instances the blocking procedures presented technical difficulties needing repeated lumbar punctures. The first case concerns a patient receiving anticoagulant and fibrinolytic therapy for vascular pathology. This 89 year-old female experienced severe cord compression requiring surgical decompression and laminectomy. The second case regards a patient with previous minor surgical procedure requiring postoperative antiinflammatory treatment. This 74 year-old male experienced subarachnoid hemorrhage and spinal/epidural hematoma as shown by NMR. The symptoms regressed with steroid therapy. The authors emphasise the risks of mechanical trauma of epidural or spinal anesthesia both during positioning or removal of an epidural catheter. The problem related to the compatibility between central blocks and antithrombotic/anticoagulant prophylaxis/therapy is now of primary concern and has led to publications about guide lines on this topic. If central block is carried out in patients with bleeding diathesis it is mandatory to co-ordinate multidisciplinary assistance for early detection of significant symptoms of the above described complications and subsequent treatment.

Aged↗
PubMed2000

Physiologic evaluation of noninvasive mechanical ventilation delivered with three types of masks in patients with chronic hypercapnic respiratory failure.

OBJECTIVE: The efficacy of noninvasive mechanical ventilation (NIMV) in improving breathing pattern and arterial blood gases (ABG) in hypercapnic patients has been well documented; however, little attention has been given to the choice of the interface and the ventilatory mode. We evaluated the effects of three types of masks and two modes of ventilation on patients' ABG, breathing pattern, and tolerance to ventilation. DESIGN: Prospective randomized study. SETTING: Two respiratory weaning centers. PATIENTS: A total of 26 stable hypercapnic patients (pH, 7.38 +/- 0.04; PaCO2, 59.2. +/- 10.9 torr) had not received NIMV and were affected by restrictive thoracic disease or obstructive pulmonary disease. INTERVENTIONS: Three 30-min runs of NIMV, delivered using volume-assisted (n = 13) or pressure-assisted modes of partial mechanical support (n = 13), were performed in random order with a full-face mask, a nasal mask, and nasal plugs. MEASUREMENTS: ABG, breathing pattern, and patients' tolerance to ventilation. MAIN RESULTS: Compared with spontaneous breathing, the application of NIMV significantly improved ABG and minute ventilation, irrespective of the ventilatory mode, the underlying pathology or the type of mask. Overall, a nasal mask was better tolerated than the other two interfaces (p < .005 vs. nasal plugs and full-face mask). PaCO2 was significantly lower (p < .01) with a full-face mask or nasal plugs than with a nasal mask (49.5 +/- 9.4 torr, 49.7 +/- 8 torr, and 52.4 +/- 11 torr, respectively). Minute ventilation was significantly higher with a full-face mask than with a nasal mask because of an increase in tidal volume. No differences were observed in tolerance to ventilation, ABG, or breathing pattern, using assist control or pressure-assisted modes. CONCLUSIONS: In this physiologic study, we have shown that in patients with hypercapnic respiratory failure, irrespective of the underlying pathology, the type of interface affects the NIMV outcome more than the ventilatory mode.

Chronic Disease↗
PubMed2000

Incidence and causes of non-invasive mechanical ventilation failure after initial success.

BACKGROUND: The rate of failure of non-invasive mechanical ventilation (NIMV) in patients with chronic obstructive pulmonary disease (COPD) with acute respiratory insufficiency ranges from 5% to 40%. Most of the studies report an incidence of "late failure" (after >48 hours of NIMV) of about 10-20%. The recognition of this subset of patients is critical because prolonged application of NIMV may unduly delay the time of intubation. METHODS: In this multicentre study the primary aims were to assess the rate of "late NIMV failure" and possible associated predictive factors; secondary aims of the study were evaluation of the best ventilatory strategy in this subset of patients and their outcomes in and out of hospital. The study was performed in two respiratory intensive care units (ICUs) on patients with COPD admitted with an episode of hypercapnic respiratory failure (mean (SD) pH 7.23 (0.07), PaCO(2) 85.3 (15.8) mm Hg). RESULTS: One hundred and thirty seven patients initially responded to NIMV in terms of objective (arterial blood gas tensions) and subjective improvement. After 8.4 (2.8) days of NIMV 31 patients (23%; 95% confidence interval (CI) 18 to 33) experienced a new episode of acute respiratory failure while still ventilated. The occurrence of "late NIMV failure" was significantly associated with functional limitations (ADL scale) before admission to the respiratory ICU, the presence of medical complications (particularly hyperglycaemia), and a lower pH on admission. Depending on their willingness or not to be intubated, the patients received invasive ventilation (n=19) or "more aggressive" (more hours/day) NIMV (n=12). Eleven (92%) of those in this latter subgroup died while in the respiratory ICU compared with 10 (53%) of the patients receiving invasive ventilation. The overall 90 day mortality was 21% and, after discharge from hospital, was similar in the "late NIMV failure" group and in patients who did not experience a second episode of acute respiratory failure. CONCLUSIONS: The chance of COPD patients with acute respiratory failure having a second episode of acute respiratory failure after an initial (first 48 hours) successful response to NIMV is about 20%. This event is more likely to occur in patients with more severe functional and clinical disease who have more complications at the time of admission to the ICU. These patients have a very poor in-hospital prognosis, especially if NIMV is continued rather than prompt initiation of invasive ventilation.

Aged↗
PubMed2000

Controlled short-term trial of fluticasone propionate in ventilator-dependent patients with COPD.

BACKGROUND: There is no agreement about the efficacy of systemic corticosteroids in patients with COPD, but corticosteroids often are employed during exacerbations of the disease. The use of systemic or inhaled corticosteroids in patients in stable condition is even more controversial, even though the more severely affected patients seem to respond better. Unfortunately, in this subset of patients, the use of forced expiratory maneuvers frequently fails to detect significant functional response. STUDY OBJECTIVES: We evaluated the short-term effects of an inhaled corticosteroid, fluticasone propionate (FP), on FEV(1) and on the mechanical properties of patients in stable condition with severe COPD and chronic hypercapnic respiratory failure who were receiving long-term ventilatory support. This allowed us to measure respiratory mechanics (RM) passively, thereby avoiding any problems linked with voluntary maneuvers. DESIGN: Randomized, placebo-controlled, crossover study. SETTING: A respiratory ICU. PATIENTS: Twelve hypercapnic COPD patients (mean [+/- SD] PaCO(2), 60+/-11 mm Hg; mean FEV(1), 13+/-5% predicted; and mean FEV(1)/FVC, 31 +/- 7%) were enrolled. INTERVENTIONS: A daily dose of 2,000 microg FP or placebo was administered via metered-dose inhaler during mechanical ventilation for 5 consecutive days. A washout of 72 h was allowed between regimens. MEASUREMENTS: End-expiratory and end-inspiratory airway occlusions were performed to assess static intrinsic positive end-expiratory pressure (PEEPi,st), static compliance of the respiratory system (Cst,rs), maximal respiratory resistance (Rmax, rs), and minimal respiratory resistance (Rmin,rs). The bronchodilator response also was assessed by FEV(1) level. RESULTS: No significant changes were found in RM after administration of the placebo. By day 6, FP had induced the following significant decreases: PEEPi,st, 4.3+/-2.4 to 3.1+/-1.7 cm H(2)O (p<0.01); Rmax,rs, 19.0+/-6.5 to 14.6+/-6 cm H(2)O/L/s (p<0.001); and Rmin,rs, 14.8+/-4.2 to 10.5+/-3.4 cm H(2)O/L/s (p<0.001). The Cst,rs and the effective additional resistance of the respiratory system did not change significantly, the latter suggesting that the major effect of FP was on the airway caliber (Rmin,rs). FEV(1) changes significantly (p<0.01) underestimated the bronchodilator response, as compared with changes in Rmin,rs. CONCLUSIONS: We conclude that in patients in stable condition with severe COPD and chronic hypercapnic respiratory failure, a brief trial of FP may induce a bronchodilator response, mainly related to a reduction in airway resistances, that is not detected by the usual pulmonary function tests.

Administration, Inhalation↗
PubMed2000

The appropriate setting of noninvasive pressure support ventilation in stable COPD patients.

STUDY OBJECTIVE: To evaluate the short-term physiologic effects of two settings of nasal pressure-support ventilation (NPSV) in stable COPD patients with chronic hypercapnia. DESIGN: Randomized controlled physiologic study. SETTING: Lung function units and outpatient clinic of two affiliated pulmonary rehabilitation centers. PATIENTS: Twenty-three patients receiving domiciliary nocturnal NPSV for a mean (+/- SD) duration of 31 +/- 20 months. METHODS: Evaluation of arterial blood gases, breathing pattern, respiratory muscles, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) during both unassisted and assisted ventilation. Two settings of NPSV were randomly applied for 30 min each: (1) usual setting (U), the setting of NPSV actually used by the individual patient at home; and (2) physiologic setting (PHY), the level of inspiratory pressure support (IPS) and external positive end-expiratory pressure (PEEPe) tailored to patient according to invasive evaluation of respiratory muscular function and mechanics. RESULTS: All patients tolerated NPSV well throughout the procedure. Mean U was IPS, 16 +/- 3 cm H(2)O and PEEPe, 3.6 +/- 1.4 cm H(2)O; mean PHY was IPS, 15 +/- 3 cm H(2)O and PEEPe, 3.1 +/- 1.6 cm H(2)O. NPSV was able to significantly (p < 0.01) improve arterial blood gases independent of the setting applied. When compared with spontaneous breathing, both settings induced a significant increase in minute ventilation (p < 0.01). Both settings were able to reduce the diaphragmatic pressure-time product, but the reduction was significantly greater with PHY (by 64%; p < 0.01) than with U (56%; p < 0.05). Eleven of 23 patients (48%) with U and 7 of 23 patients (30%) with PHY showed ineffective efforts (IE); the prevalence of IE (20 +/- 39% vs 6 +/- 11% of their respiratory rate with U and PHY, respectively) was statistically different (p < 0.05). CONCLUSION: In COPD patients with chronic hypercapnia, NPSV is effective in improving arterial blood gases and in unloading inspiratory muscles independent of whether it is set on the basis of patient comfort and improvement in arterial blood gases or tailored to a patient's respiratory muscle effort and mechanics. However, setting of inspiratory assistance and PEEPe by the invasive evaluation of lung mechanics and respiratory muscle function may result in reduction in ineffective inspiratory efforts. These short-term results must be confirmed in the long-term clinical setting.

Aged↗