Nabil Abou-Shala

Noninvasive mechanical ventilation via face mask in patients with acute respiratory failure who refused endotracheal intubation

Objective: To evaluate the response to noninvasive ventilation in a group of terminally ill patients with acute respiratory failure who refused endotracheal intubation. Design: Case series. Setting: Medical intensive care units (ICUs) in a university health science center. Patients: Eleven patients, nine with hypercapnic and two with hypoxemic acute respiratory failure. Mean age of patients was 64 yrs. Intervention: Mechanical ventilation was delivered via a face mask. The initial ventilatory setting was continuous positive airway pressure mode, with pressure‐support ventilation of 10 to 20 cm H2O, titrated to achieve a respiratory rate of <25 breaths/min and a tidal volume of 5 to 7 mL/kg. Ventilatory settings were adjusted based on results of arterial blood gases. Mean duration of mechanical ventilation was 44 hrs. Measurements and Main Results: Mechanical ventilation via face mask was effective in correcting gas exchange abnormalities in seven of 11 patients, all of whom survived and were discharged from the ICU. Four patients with hypercapnic acute respiratory failure died. Mechanical ventilation via face mask was effective in improving respiratory acidosis in three patients and had no effect in one patient. Two of the four patients could not be weaned from mechanical ventilation and opted for discontinuation of this method. Removal of the ventilator while retaining the mask for oxygen supplementation was a nontraumatic experience to the patient and family. Even when respiratory failure did not resolve, mechanical ventilation via face mask was effective in lessening dyspnea and allowed the patient to maintain autonomy and continuous verbal communication. Conclusions: We conclude that mechanical ventilation via face mask offers an effective, comfortable, and dignified method of supporting patients with end‐stage disease and acute respiratory failure. (Crit Care Med 1994; 22:1584–1590)

Noninvasive mechanical ventilation in patients with acute respiratory failure.

OBJECTIVES a) To describe the introduction of noninvasive means to provide positive-pressure ventilation in acute respiratory failure; b) to describe the physiologic response to noninvasive ventilation; c) to review the current published literature on using noninvasive ventilation in patients with acute hypercapnic and/or hypoxemic respiratory failure; d) to describe the technique of applying mask ventilation and current recommendations for using noninvasive ventilation and current recommendations for using noninvasive ventilation in patients with acute respiratory failure; and e) to discuss the advantages and disadvantages of noninvasive ventilation. DATA SOURCES All relevant articles published in the English medical literature from 1988 through August 1994 were retrieved through a MEDLINE search, as well as from the authors experience. STUDY SELECTION Studies were selected based on the use of positive-pressure mechanical ventilation delivered, using facial or nasal masks in various acute settings of respiratory failure. DATA EXTRACTION The authors extracted all applicable data. DATA SYNTHESIS Studies were analyzed according to the type of respiratory failure (hypercapnic vs. hypoxemic) and underlying conditions where noninvasive ventilation seemed to be a better alternative. The results were evaluated based on types of masks used and modes of ventilation. Outcome measures were compared based on studies that randomized patients with acute respiratory failure to receive noninvasive vs. conventional therapy. Complications of noninvasive ventilation, mainly local, were compared with those complications seen endotracheal intubation in acute respiratory failure patients. CONCLUSIONS Noninvasive ventilation is a safe and effective means of ventilatory support for many patients with acute respiratory failure. Noninvasive ventilation is well tolerated, principally because it allows the patient to be in control and to continue verbal communication, and should be strongly considered in managing terminally ill patients with potentially reversible causes of respiratory failure. The duration of mechanical ventilation and its associated complications are significantly decreased in hypercapnic respiratory failure with noninvasive ventilation.

Reassessing the Therapeutic Range for Theophylline on Laboratory Report Forms: The Importance of 5–15 μg/ml

The therapeutic status of theophylline has changed dramatically over the last decade. As part of this change, a different view of the most appropriate therapeutic range for serum theophylline concentration (STC) has emerged. The National Institutes of Health Expert Panel Report, “Guidelines for the Diagnosis and Management of Asthma,” suggests a conservative approach of aiming for STC of 5–15 μg/ml. This truly landmark document along with several studies in the literature, recently prompted us to change our hospitals laboratory report form for the medical record to read that the therapeutic rage for STC is 5–15 μg/ml. We encourage hospital laboratories or other clinical laboratories who have not already made this change to do so.

Is Theophylline Use Justified in Acute Exacerbations of Asthma

Despite widespread use of theophylline in the hospital management of asthma, supportive data justifying its use are sparse. Clinical research in the 1980s has forced a serious new examination of the drugs role in acute exacerbations of asthma. Because of the morbidity, mortality, questionable value, and overall cost of theophylline therapy, this reevaluation is of particular importance. Enhanced knowledge of the value of treatment with intensive inhaled ß agonists, systemic glucocorticoids, and inhaled ipratropium should prompt elimination of the routine, initial use of theophylline in emergency room care of most asthmatics. Further research is necessary to justify the routine, initial use of the drug in hospitalized asthmatics.

Two- and four-day rifampin chemoprophylaxis regimens induce oxidative metabolism.

The effects of two short-term chemoprophylaxis regimens of rifampin (2 or 4 days) on oxidative metabolism were investigated in 14 healthy subjects. Seven subjects received 600 mg of rifampin twice daily on study days 6 and 7 (group A), and seven subjects received 600 mg of rifampin once daily on days 4, 5, 6, and 7 (group B). Antipyrine (18 mg/kg of body weight) was administered orally on days 1, 8, and 15. Short-term rifampin regimens increased oral clearance of antipyrine in both groups compared with the baseline value (P less than 0.05), and group B displayed a larger percent increase over the baseline value than group A did (70.5 +/- 14.3 versus 33.1 +/- 18.1; P less than 0.05). The partial metabolic clearance (CLM) of antipyrine to 3-hydroxymethylantipyrine (HMA) on day 8 increased 71 and 108% for regimens A and B, respectively (P less than 0.05 for both). The corresponding increases in CLM to norantipyrine (NORA) were 57 and 98% (P less than 0.05 for both). CLM to 4-hydroxyantipyrine (OHA) on day 8 increased 64% for regimen A (P = 0.08) and 97% for regimen B (P less than 0.05) compared with the baseline. Although CLM to HMA and OHA on day 15 remained greater than 50% over the baseline with both regimens, CLM to NORA on day 15 was less than 25% over the baseline with both regimens. Thus, both short-term rifampin chemoprophylaxis regimens increased antipyrine clearance for at least 1 week. The increase tended to be higher with the 4-day regimen. The pattern observed for the CLMS suggests that more than one P-450 enzyme is affected.