الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The incidence and severity of asthma have increased in recent years, and the number of asthma patients who developed acute respiratory failure (ARF) and were admitted to intensive care unit (ICU) has also increased. ARF in asthma is called status asthmaticus (SA) and did not respond to conventional medical therapy within 24 hours and refers to a severe deterioration in gas exchange that may require mechanical ventilation (MV) for life support.
Patients with SA presented a significant increase in both inspiratory and expiratory indexes of airway obstruction and high levels of dynamic hyperinflation. The inspiratory muscles maintain their contraction throughout the entire respiratory cycle, but overdistension of the chest shortens these muscles and reduces their efficiency. Finally, respiratory muscle fatigue and increased physiological dead space lead to respiratory acidosis and ventilatory failure.
Endotracheal intubation (ETI) and MV are required in patients with asthma and hypercapnia who develop exhaustion of the ventilatory muscles or life-threatening complications such as hypotension, arrhythmias and decreased level of consciousness. Nevertheless, ETI and invasive MV are associated with substantial morbidity and mortality rates. As a result, less harmful methods of providing ventilatory support need to be found.
Several studies suggest that non-invasive mechanical ventilation (NIMV) added to the standard pharmacological therapy might be involved in various forms of hypercapnic acute respiratory failure. NIMV mainly works by improving alveolar ventilation and ameliorating muscle fatigue, relieving dyspnea and avoiding the unnecessary risks and discomfort associated with the endotracheal tube. The term NIMV encompasses a range of techniques for augmenting alveolar ventilation without an artificial airway. Continuous positive airway pressure (CPAP) and non-invasive intermittent positive pressure ventilation (NPPV) via a facemask are the most common methods.
The aim of this present study was to evaluate the efficacy of noninvasive continuous positive airway pressure (CPAP) facemask in the treatment of status asthmaticus.
The present study was conducted on 20 patients presented with status asthmaticus who failed to respond to conventional medical therapy. At the time of presentation, each patient was subjected to history taking, full clinical assessment, arterial blood gases evaluation (ABG) and electrocardiographic evaluation just before beginning mask ventilation. Then the patients started to receive the specific routine medical treatment.
CPAP mask ventilation was initiated within minutes as an alternative to invasive mechanical ventilation. The procedure was explained to the patient and the mask was applied by hand for few minutes until the patient could tolerate it, then the mask was fitted by head and chinstraps to prevent significant air leak.
Arterial blood pressure, pulse rate, respiratory rate and ABG evaluation were assessed immediately before CPAP mask application then after 30, 60, and 90 minutes.
During the first 30 minutes, the decision to continue the mask or to shift to invasive mechanical ventilation and endotracheal intubation (ETI) was done according to the clinical and gasometric data.
The age of the studied patients ranged between 40 and 70 years. Fourteen patients were males (70 %) and six patients were females (30 %).
The following results were obtained:
Pulse rate decreased significantly in the majority of patients throughout the study compared to the time of presentation.
Respiratory rate showed highly statistically significant decrease in the majority of patients throughout the study compared to the time of presentation.
Blood pressure changes were not significant changes in all patients throughout the study.
There was a significant increase in arterial oxygen tension (PaO2) in the majority of patients throughout the study. This increase may be due to recruitment of the underventilated alveoli.
There was a significant increase in arterial oxygen saturation (SaO2) in the majority of patients throughout the study. This increase may be also due to recruitment of the underventilated alveoli.
Arterial CO2 tension (PaCO2) decreased significantly in the majority of cases throughout the study.
pH increased in all patients but it was significant only after 60 and 90 minutes compared to the time of presentation. The improvement in the respiratory acidosis was probably due to actual improvement in alveolar ventilation due to the decrease in dead space with improvement of dyspnea and shallow breathing.
HCO3 changes were not significant in all patients throughout the study.
There were no significant ECG changes in all patients throughout the study.
17 patients showed complete recovery with CPAP mask application and did not need ETI. 3 patients failed and need ETI within the first 30 min. judged on clinical and gasometric bases as the use of the mask failed to improve their hypoxemia and hypercabnia. All failed patients showed complete recovery after ETI & MV.
The ICU stay time (days) and total hospital stay time (days) in succeeded patients was shorter than that of failed cases.
There were no significant complications from CPAP mask ventilation throughout the study.