الفهرس 
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Abstract
Chronic obstructive pulmonary disease is a common, treatable, and preventable illness marked by persistent respiratory symptoms and airflow limitation as a result of abnormalities in the airways and/or alveoli. These abnormalities are typically brought on by prolonged exposure to harmful particles or gases and are impacted by host risk factors such as abnormal development of the lung. AECOPD is an episode characterized by increased dyspnea, coughing and expectoration that worsens in less than two weeks. It may also be associated with increased HR and/or RR and it is often linked with increased inflammation both locally and systemically caused by infection, pollutants, or another airway insult.
Hypercapnic respiratory failure is an increase in PaCO2 more than 45 mmHg with a pH less than 7.35 because of respiratory pump failure and/or increased CO2 production.
Acute hypercapnic respiratory failure is a common AECOPD complication, and is linked with an increased requirement of respiratory support and a high risk of mortality. NIV is recommended as the gold-standard in management of COPD patients complicated by AHRF . However, NIV may not be well tolerated, and about 25% of subjects have contraindications to NIV.
High Velocity Nasal Insufflation, a type of HFNC that uses a tiny bore NC to replace larger bore HFNC create greater gas delivery velocities. With flow rates of thirty-five liters per minute, it can completely clear extrathoracic dead space and in those suffering from acute type II respiratory failure, besides oxygenation support, it may also be able to provide ventilatory assistance.
Patients with respiratory distress owing to pulmonary causes, as dyspnea, hypoxia, CO2 retention, or extra-pulmonary causes of respiratory distress, can benefit from Hi-VNI that is a form of NIV without face mask. Hi-VNI has an advantage over HFNC in that, even at 40 l/min, the small-bore cannulas generate higher velocity, rapidly eliminating expiratory gas with a high CO2 content from dead space in the upper airways. So, a new gas reservoir is produced and reduce the WOB. ARF Patients with elevated RR and short intervals among breaths for gas exchange benefit from Hi-VNI.
Brochard et al., 1995 & Nishimura, 2016 found that the response of the individuals to HFNC varied: For some, RR declined, and for others, PaCO2 declined.
The current study aimed to assess the effect of Hi-VNI oxygen therapy in management of AHRF in AECOPD and to compare Hi-VNI to NIV in management of AHRF in AECOPD.
The present study was done at the respiratory ICU at Cardiothoracic Minia University Hospital on 74 AECOPD cases admitted by AHRF. The patients were divided into two groups based on the first line of ventilatory support used, including NIV group (40 case) and Hi-VNI group (34 case). Patients were subjected to the following: Clinical examination, routine laboratory tests, plain chest radiographs, computed tomography if needed, ABGs analysis on admission, one hour, two hours, six hours, twenty-four hours, and at discharge, ECG and echocardiography if needed.
In the Hi-VNI group, using Precision Flow Plus, Vapotherm, INC. U.S.A. device, the interface was a small-bore NC which resulted in high velocity out of the nasal prongs. The initial flow at 35 L/min; temperature 35: 37◦C, FiO2 1.0. The FiO2 was adjusted to obtain a SpO2 between 88 and 92%.
Non-invasive positive pressure ventilation, using AVEA ventilator USER INTERFACE MODULE or Maquet caro AB Servo-a BASE UNIT, with an oronasal mask and starting settings of 10:20 cm/H2O IPAP, 5:10 cm/H2O EPAP, and an FiO2 of 1.0. Vital signs and ABG were recorded before the initiation of therapy then after 1,2, 6, 24 and on discharge hours of therapy initiation.
This study reported that there was insignificant difference regarding demographics data among NIV group and Hi-VNI group, there were statistically insignificant differences regarding age, sex, BMI, marital status, residence and smoking (p value>0.05) and there were statistically insignificant variations regarding comorbidities, history of COPD in years, history of ICU admission, medication before exacerbation, presence of purulent sputum and pneumonia (p value>0.05).
By comparing baseline vital data among NIV group and Hi-VNI group, our findings revealed that there were non-statistically significant variations regarding HR, SBP, DBP, RR, O2 saturation and conscious level (p value>0.05).
The current study showed by comparing some laboratory data between NIV group and Hi-VNI group, there were non-statistically significant variations regarding CBC (hemoglobin, TLC, and platelet), CRP, renal function tests (urea and creatinine) and serum electrolyte (Na, K and ionized Ca) (p value>0.05).
The current study’s comparing of the RR, PH, PaCO2, PaO2, and HCO3 in the NIPPV group and in the Hi-VNI group at admission, as well as at 1 hour, 2hrs, 6hrs, 24hrs, and at discharge, revealed statistically insignificant variation (p value >0.05) among the two groups. While inside each group, there were statistically significant decrease in RR and PaCO2 at 1hr compared to baseline RR and PaCO2, also at 2hrs, 6hrs, 24hrs and on discharge compared to RR and PaCO2 on admission either in NIV group or in Hi-VNI group and there was statistically significant increase in the values of PH and PaO2 at 1hr compared to baseline PH and PaO2, also at 2hrs, 6hrs, 24hrs and on discharge compared to baseline either in NIV group or in Hi-VNI group. But there was non-statistically significant change in HCO3 at 1 hour, 2hrs, 6hrs, 24hrs and on discharge compared to HCO3 on admission either in NIV group or in HI-VNI group (P value >0.05).
We found that there were statistically significant variations among both groups regarding complication as Facial breakdown, Anxiety claustrophobia, Eye irritation, Inability to communicate more in NIV group but Nasal irritation occurred more in Hi-VNI (p value <0.05).
By comparing both groups as regards clinical outcomes, the present study showed that there were statistically significant variations among the two groups as regards shift to another device.
By comparing both groups as regards causes of treatment failure, our result found that there were statistically insignificant variations (p value >0.05) regarding deterioration of conscious level, aggravation CO2 retention, aggravation of hypoxia and treatment intolerance. While there was statistically significant variation regarding aggravation of respiratory distress (p value <0.05) which was more presented in the NIV group.
By comparing both succeeded and failed cases in NIV group, we found that there were statistically significant regarding HR, RR, temperature and conscious level (p value <0.05). While there were non-statistically significant variations among cases showed success in treatment and cases showed failure in treatment regarding age, sex, BMI, smoking, co-morbidities, history of COPD, ICU admission, purulent sputum, pneumonia, SBP, DBP, O2 saturation and all ABG parameter (p value >0.05).
By comparing both succeeded and failed cases in Hi-VNI group, our findings elucidated that there were statistically significant variations as regards pneumonia and RR (p value <0.05). While there were statistically insignificant variations between cases who succeed treatment and cases who failed treatment regarding age, sex, BMI, smoking, co-morbidities, history of COPD, ICU admission, purulent sputum, HR, SBP, DBP, temperature, O2 saturation and all ABG parameter (p value >0.05).
the results of binary logistic regression analysis for predictors of failure of treatment among NIV group, revealed after adjusting for other factors affecting failure, that two variables (RR on admission and Conscious level) retained the significance in the multivariable model. As regard Conscious level, patients who were confused had 8.6 times more risk of failure of treatment (OR=8) compared to cases who were fully conscious and DCL cases had more than 1000 times risk for failure of treatment compared to fully conscious cases with significant p value <0.05. For RR on admission, every increase in RR by one unit will be met by increase in rate of failure by 10%.
Our results of binary logistic regression analysis for predictors of failure of treatment among Hi-VNI group, revealed after adjusting for other factors affecting failure, that one variable (conscious level) retained the significance in the multivariable model as conscious level, patients who were confused had 3 times more risk of failure of treatment (OR=3.1) compared to cases who were fully conscious and DCL cases had more than 1000time risk for failure of treatment compared to fully conscious cases with significant p value <0.05.