الفهرس 
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Abstract
Patients with respiratory failure may require mechanical ventilation for weeks or longer and this prolonged time increases the risk of serious patients complications, These complications include ventilator-associated pneumonia, airway injury, laryngeal injuries, barotrauma, gastrointestinal bleeding, thromboembolism, bed sores, muscle atrophy and some of those complications increase with the duration of intubation and may increase mortality. So, it is required to wean patients from the ventilator as soon as spontaneous breathing is possible. Weaning success is typically defined as extubation and the absence of ventilatory support 48 hours following the extubation. Whereas weaning failure is defined as one of the following: Failed spontaneous breathing trials, reintubation and/or resumption of ventilatory support following successful extubation, or death within 48 hours following extubation. There are innumerable factors responsible for the failure of weaning from mechanical ventilation as clinical factors contributing to respiratory muscles dysfunction, clinical factors contributing to cardiac dysfunction, clinical factors contributing to neurological dysfunction, clinical factors contributing to endocrine, metabolic dysfunction and other factors as severity of illness, presence of bedsores in addition to weaning trial readiness and tolerance. Hence, this study was conducted to identify factors contributing to weaning failure among mechanically ventilated patients with acute respiratory failure.
The aim of this study:
A descriptive research design was used to identify clinical factors contributing to weaning failure among mechanically ventilated patients with acute respiratory failure.
Materials and method:
This study was carried out at the following ICUs at Alexandria Main University Hospital; unit I (14 beds), unit II (8 beds), and unit III (15 beds) and El-Moassat hospital general ICU that includes (14 beds). The general ICUs receive patients who have a variety of disorders in acute stage of illness admitted directly from the emergency room or transferred from other departments.
A convenience sample of 60 adult mechanically ventilated patients with acute respiratory failure from the first day of mechanical ventilation. Patients who have neurological disorders as cerebrovascular stroke, brain tumors or malignant lung tumors, kidney tumors and with prolonged mechanical ventilation (>21 days) will be excluded from the study.
To accomplish the aim of the current study; one tool was used for data collection. Tool one: Clinical factors contributing to weaning failure assessment. This tool was developed by the researcher after reviewing the relevant literature to assess clinical factors contributing to weaning failure among mechanically ventilated patients with acute respiratory failure. It consists of two parts: Part I: Demographic and clinical data record.
This part was used to assess demographic and clinical data .Demographic data such as age, sex. Clinical data such as past history data as history of smoking, co-morbidities, admission related data as admission medical diagnosis, reasons of ventilation, APACHE II score, current medications such as sedatives, antibiotics, corticosteroids and vasopressors. Invasive devices data as presence of feeding tube, type and size of tracheal tube duration of tracheal tube and duration of mechanical ventilation (days). These parameters were recorded by the researcher in an assessment sheet.Part II: clinical factors contributing to weaning failure.
This part includes: clinical factors contributing to respiratory muscles dysfunction as oxygenation parameters, presence of anemia; lab investigation (hemoglobin, hematocrit), ventilation parameters, and incidence of aspiration. Clinical factors contributing to cardiac dysfunction as hemodynamic parameters; heart rate (b/min), mean arterial pressure (mmHg) and CVP (CmH2O). Clinical factors contributing to neurological dysfunction as level of consciousness by using four score, pain level by using CPOT, level sedation by using RASS, presence of delirium by using CAM-ICU. Clinical factors contributing to endocrine and metabolic dysfunction as blood glucose level; using random blood sugar, electrolyte imbalance; sodium, potassium, calcium levels and gastric residual volumes. Other factors as severity of illness, presence of bedsore; assessment of the skin using Braden scale and weaning readiness and tolerance.
The study design was accomplished as follow:
An official letter from the Faculty of Nursing was sent to the appropriate authorities in the Main University Hospital (MUH). Permission to conduct the study with explanation of the aim of the study was obtained.
The study tool was developed by the researcher after reviewing the related literature. And this study tool was submitted to a jury of 5 experts in critical care nursing, critical care medicine to assess the content of the tool and all necessary modifications were made.
A pilot study was carried out on six patients who represent 10% of sample size in order to test the feasibility and applicability of the tool and all the necessary modifications were made accordingly and these patients weren’t included in the study as add size of tracheal tube. The pilot sample was excluded from the study subjects.
Reliability was not tested because the tool is not a Likert scale and was developed by the researcher with its value measured based on the answer of yes or no.
Data were collected by the researcher during approximately (four months) starting from the beginning of January 2019 till the end of April. Results of the current study were as follow:
Most of the studied patients in this study were males; aged more than fifty six years old. Furthermore, most of the patients were admitted to ICU with respiratory disorders without history of smoking. Also, regarding admission related data; most of the patients were admitted with hypoventilation as the reasons of ventilation and most of them were with a high APACHE II score.
Regarding frequency distribution of studied patients according to clinical factors and weaning status. There was statistically significant association between the occurrence of weaning failure for the studied patients and respiratory muscles dysfunction as (oxygenation parameters, ventilation parameters) of the studied patients, this finding was evidenced by the statistically significant association for high FiO2 (P=0.001), low PaO2 (P=0.001), presence of anemia (P=0.038). Also PH alkalemia (P=0.007), Spontaneous inspiratory effort (P=0.037).
There was statistically significant association between the occurrence of weaning failure and cardiac dysfunction for the studied patients as hemodynamic parameters, this finding was evidenced by the statistically significant association for increase heart rate (P=0.002) and high CVP (P=0.010).
There was statistically significant association between the occurrence of weaning failure and neurological dysfunction for the studied patients as decrease level of consciousness (P=0.001), use of sedation (P=0.002) and presence of delirium (P=0.003).
There was statistically significant association between the occurrence of weaning failure and severity of illness for the studied patients. It was found the higher severity of illness (P=0.018).
There was statistically significant association between the occurrence of weaning failure and weaning trial readiness for the studied patients (P=0.001).
There was statistically significant association between the occurrence of weaning failure and weaning trial tolerance for the studied patients (P=0.001).
As regard the relation between to past history data and weaning status. There was statistically significant association between occurrence of weaning failure and Co-morbidities for studied patients that was found respiratory disorder (p= 0.004).
According to multivariate regression analysis for factors affecting the weaning status hours showed that clinical factors contributing to neurological dysfunction as delirium is the most significant factor affecting weaning trial (p=0.011), followed by increase severity of illness by SOFA Score (p= 0.020), then clinical factors contributing to respiratory muscles dysfunction as oxygenation parameters high FiO2 (p=0.030), low PaO2 (p= 0.033) and presence of anemia (p=0.042) and finally, clinical factors contributing to neurological dysfunction as use of sedation (p=0.049).
Conclusion
Based on the findings of the current study, it can be concluded that:
The majority of the studied mechanically ventilated patients with acute respiratory failure have developed weaning failure. There were multiple clinical factors that could contribute to weaning failure among mechanically ventilated patients. Based on the results of this study, it can be concluded that the clinical factors contributing to neurological dysfunction (presence of delirium, use of sedation), increase severity of illness, clinical factors contributing to respiratory muscles dysfunction (high FiO2 and low PaO2, presence of anemia) were the most significant risk factors to weaning failure according to binary logistic regression analysis.
Recommendations
Assess the patients’ indicators for weaning from mechanical ventilation.
Identify the updated weaning protocols which used to reduce the duration of mechanical ventilation.
Observe mechanically ventilated patients tolerance to the weaning trials to identify the weaning failure and to decide consequent actions collaboratively with the physician.
Develop educational programs to raise critical care nurses awareness regarding assessment of clinical factors which can effect ventilator weaning process to prevent weaning failure.
Formulate evidence-based guidelines and standards for assessing mechanical ventilated patients who are risky to weaning failure. Further studies are needed to identify nursing practices associated with the weaning failure.
Replication of the current study on large sample size, longer duration of data collection and different setting for generalization of the results.