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Biomedical subjects

A G Duarte

Publications and source records attributed to A G Duarte.

11 recordsLinked to original sources
PubMed2001

Inhalation therapy during mechanical ventilation.

An increasing number of pharmacologic agents, including bronchodilators, prostaglandin, proteins, surfactant, mucolytics, and antibiotics are administered to mechanically ventilated patients by the inhalation route. To achieve a therapeutic effect, adequate amounts of an inhaled agent must be delivered to the desired site of action. The delivery of inhaled drugs to the lower respiratory tract of mechanically ventilated patients is complicated by deposition of the aerosol particles in the ventilator circuit and endotracheal tube, and the factors governing pulmonary deposition in mechanically ventilated patients are different from those in ambulatory patients. Meticulous adherence to several steps in the technique of aerosol administration is necessary for successful aerosol therapy in mechanically ventilated patients. With a proper technique of administration, an increasing number of inhaled drugs may be administered safely, conveniently, and effectively to mechanically ventilated patients.

Aerosols↗
PubMed2001

Pregnancy and primary pulmonary hypertension : successful outcome with epoprostenol therapy.

Primary pulmonary hypertension (PPH) associated with pregnancy carries a high maternal mortality rate. Short-term epoprostenol infusion has been demonstrated to improve the hemodynamic profile in patients with PPH. We report a successful maternal-fetal outcome with epoprostenol therapy during pregnancy, cesarean section, and postpartum in a patient with PPH. Epoprostenol therapy did not produce any physical or developmental abnormalities in the fetus. A favorable maternal-fetal outcome may occur with a multidisciplinary approach.

Adult↗
PubMed2000

Pathogenesis and management of respiratory insufficiency following pulmonary resection.

The underlying principle of the surgical treatment of non-small-cell lung cancer (NSCLC) is complete removal of the local/regional disease within the thorax. Pulmonary resection should be as conservative as possible without compromising the adequacy of tumor removal. A multitude of factors influence the incidence and severity of complications following pulmonary resection including the pre-operative physical and psychological status of the patient, the pathologic process requiring resection, the physiologic impact of the procedure, and the addition of pre-operative or postoperative adjuvant therapy. The insidious onset of interstitial changes on chest X-ray (CXR) 1 to 2 days after pulmonary resection forewarns of respiratory distress; however, the pathophysiology of adult respiratory distress syndrome (ARDS) with progression to respiratory failure requiring mechanical ventilation and advanced critical care often unfolds. Management of patients with severe respiratory failure remains primarily supportive. "Good critical care" is the mainstay of therapy: this includes gentle mechanical ventilation to avoid ventilator-induced barotrauma and over-extension of remaining functional alveoli, diuresis, infection identification and management, and nutritional support. New therapeutic strategies that may impact on outcomes in the adult population include pressure-limited ventilation (permissive hypercapnia), inverse ratio ventilation, high-frequency jet ventilation, high-frequency oscillatory ventilation, intratracheal pulmonary ventilation, and prone position ventilation. In addition, alternative therapies such as partial liquid ventilation, inhaled nitric oxide, and extracorporeal techniques including extracorporeal membrane oxygenation (ECMO), extracorporeal carbon dioxide removal (ECCO(2)R), intravascular oxygenation (IVOX), and arteriovenous carbon dioxide removal (AVCO(2)R), provide additional modalities. A component of some or all of these strategies is finding a role in clinical practice.

Carcinoma, Non-Small-Cell Lung↗
PubMed2000

Bronchodilator therapy with metered-dose inhaler and spacer versus nebulizer in mechanically ventilated patients: comparison of magnitude and duration of response.

OBJECTIVE: Four-hour comparison of the bronchodilator response of albuterol administered via metered-dose inhaler (MDI) with spacer versus small-volume nebulizer (SVN) to mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). DESIGN: Prospective randomized clinical trial. SETTING: Medical intensive care unit in a university hospital. PATIENTS: Thirteen mechanically ventilated COPD patients. INTERVENTION: Albuterol administration of 4 puffs (0.4 mg) or 10 puffs (1.0 mg) via MDI with spacer or 2.5 mg via SVN to mechanically ventilated patients in order to assess the bronchodilator response over 4 hours. MEASUREMENTS AND RESULTS: Mechanically ventilated patients were enrolled in a randomized crossover study wherein one group received 4 puffs (0.4 mg) or 2.5 mg of albuterol and another group received 10 puffs (1.0 mg) or 2.5 mg of albuterol on separate days. Respiratory mechanics measurements were obtained over 4 hours. Total airway resistance declined by 14.4 +/- 3.8% after 4 MDI puffs, 18.3 +/- 1.8% after 10 MDI puffs, or 13.7 +/- 2.6% after 2.5 mg via SVN, compared to baseline (p < 0.01). After albuterol delivery, airway resistance remained improved for 90-120 minutes (p < 0.05) and returned to baseline by 4 hours with all treatments. CONCLUSION: The airway response to albuterol administration via MDI and SVN to mechanically ventilated patients was similar in magnitude and duration, returning to baseline by 240 minutes. In stable, mechanically ventilated COPD patients, albuterol may be administered via MDI with spacer or via SVN every 4 hours.

Administration, Inhalation↗
PubMed1996

Aerosol delivery from a metered-dose inhaler during mechanical ventilation. An in vitro model.

Successful bronchodilator therapy with a metered-dose inhaler (MDI) in intubated, mechanically ventilated patients requires adequate delivery of aerosol to the lower respiratory tract. We determined the effect of ventilator mode, inspiratory flow pattern, humidity, and spontaneous respiratory effort on albuterol delivery in a model of the trachea and bronchi. The model was ventilated through an endotracheal tube during controlled mechanical ventilation (CMV), assist control (AC), pressure support (PS), and continuous positive airway pressure (CPAP), separately with a dry and humidified ventilator circuit. Delivery of albuterol administered by a MDI and spacer on filter placed at the ends of the bronchi was measured by spectrophotometry (246 nm). Under dry conditions and with a frequency of 10 breaths/min, albuterol delivery with CMV (VT, 800 ml; 30.3 +/- 3.4%), AC (VT, 800 ml; 31.9 +/- 1.3%), PS 10 cm H2O (VT, 700 ml; 28.8 +/- 4.5%), or PS 20 cm H2O (VT, 800 ml; 30.9 +/- 1.8%) was lower than that observed with simulated spontaneous breaths with CPAP (VT, 800 ml; 39.2 +/- 1.4%) (p < 0.01 for all modes). Delivery was greater under dry (28.8 to 39%) than under humidified conditions (15.9 to 20.2%) (p < 0.005 in all modes). Albuterol delivery showed a linear correlation with both inspiratory time and duty cycle (r > 0.91). Lower respiratory tract delivery of aerosol from a MDI varied from 4.9 to 39.2%. We conclude that in addition to other known factors such as dose, type of spacer, and its position the technique of administering MDIs in mechanically ventilated patients markedly influences lower respiratory tract aerosol delivery.

Aerosols↗
PubMed1996

Dose-response to bronchodilator delivered by metered-dose inhaler in ventilator-supported patients.

In nonintubated patients, metered-dose inhalers (MDIs) are accepted as the most convenient, efficient, and cost effective method of administering inhaled bronchodilators. Recent studies have demonstrated the efficacy of MDIs in ventilator-supported patients; however, the optimal dose of a bronchodilator from a MDI is unknown. We determined the response to increasing doses of albuterol administered by a MDI and cylindrical spacer to 12 mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). Four, eight, and 16 puffs of albuterol were given at 15-min intervals. Rapid airway occlusion were performed before and at 5-min intervals after albuterol for 80 min. Respiratory mechanics were also measured for 60 min in another group of seven patients with COPD who received four puffs of albuterol. Significant decrease in airways resistance occurred after administration of albuterol (p < 0.001). The decrease in airway resistance with four puffs of albuterol was comparable to that observed with cumulative doses of 12 puffs (p = 0.12) and 28 puffs (p = 0.25). Heart rate increased significantly (p < 0.01) after a cumulative dose of 28 puffs. The decrease in airway resistance was sustained for 60 min in the group that received only four puffs of albuterol (p < 0.003). In conclusion, four puffs of albuterol given by a MDI and spacer provided the best combination of bronchodilator effect and safety in stable mechanically ventilated patients with COPD.

Administration, Inhalation↗
PubMed1996

Serum albuterol levels in mechanically ventilated patients and healthy subjects after metered-dose inhaler administration.

In mechanically ventilated patients, systemic blood levels of inhaled drugs reflect absorption from the lower respiratory tract alone since, unlike nonintubated patients, oropharyngeal and gastrointestinal absorption cannot occur. To determine the efficiency of aerosol administration by a metered-dose inhaler (MDI), we measured serum albuterol levels after administration by a MDI and spacer to nine mechanically ventilated patients (10 puffs) and to 10 healthy subjects (six puffs). Serum albuterol levels (+/- SEM) quantitated by high-performance liquid chromatography and electrochemical detection were: 0.09 +/- 0.04 mg/ml/puff at baseline, 0.66 +/- 0.10 at 5 min, 0.98 +/- 0.10 at 10 min, 0.56 +/- 0.08 at 15 min, and 0.37 +/- 0.03 at 30 min in mechanically ventilated patients versus zero at baseline, 0.89 +/- 0.12 at 5 min, 1.27 +/- 0.13 at 10 min, 0.84 +/- 0.09 at 15 min, and 0.53 +/- 0.07 at 30 min in control subjects (p > or = 0.07 at 5, 10, and 30 min; p < or = 0.05 at baseline and at 15 min). Area under the curve (AUC0-30) in the mechanically ventilated patients was 16.8 +/- 1.4 versus 23.4 +/- 1.9 ng/ml/puff x min in control subjects (p = 0.014). In summary, administration of albuterol with a MDI achieved a profile of serum levels in mechanically ventilated patients similar to that in healthy control subjects, but the peak serum level and systemic bioavailability (AUC0-30) were lower in the patients. In conclusion, serum levels reliably assess lower respiratory tract deposition of albuterol, and show that MDIs are more efficient for aerosol delivery in mechanically ventilated patients than was previously reported in studies using radiolabeled aerosols.

Aged↗
PubMed1982

Probiotics: nonantigenic tissue fractions in cancer control.

The effects of probiotics, nonantigenic fractions of normal and malignant cells on tumors, and of similar fractions of normal cells on bacteria and viruses are discussed. The effects are considered in relation to tumor growth and development. In a control group of mice given subcutaneous inoculations only of viable dbrB tumor cells in DBA/1 mice, 100% developed tumors. In a group receiving subcutaneous and intravenous injections of tumor cells and given the tumor fractions, 20% developed lung tumors and 53% developed subcutaneous tumors. In an experiment in which mice received only intravenous injections of viable tumor cells and the tumor fractions, 100% of the controls died with no deaths occurring in the treated group. It is concluded that nonantigenic cellular fractions (probiotics) effective in inducing resistance to some bacterial and viral diseases are effective in inducing resistance to tumors in an inbred strain of mice.

Animals↗