EFFECT OF DURATION OF VENTILATION AND UNDERLYING ETIOLOGY ON THE OUTCOME OF PATIENTS RECEIVING VENTILATORY SUPPORT IN CORONARY CARE UNIT.
Objective: To determine the frequency of patients undergoing ventilatory support in coronary care unit of AFIC and NIHD, Rawalpindi and to assess the association between duration of stay and etiology with outcome of the patients.
Study Design: Comparative cross-sectional study.
Place and Duration of Study: Coronary Care unit (CCU-1) of Armed Forces Institute of Cardiology and National Institute of Heart Diseases Rawalpindi, from 1st Jan2016 till 31st Dec2016.
Material and Methods: All the patients who underwent ventilatory support in coronary care unit during our study period were included using consecutive sampling.Data collection tool comprising different demographic and clinical variables related toventilatory support was used.
Results: There were 118 patients who underwent ventilatory support in coronary care unit-1 during our study time period. The mean age of the patients was 61.2+-4.8 years. Male patients were more in number 73(61.9%).The most frequent etiology with which patients underwent ventilation was acute left ventricular failure (LVF) due to myocardial infarction 59(50.2%), followed by arrhythmias. 69(58.5%) patients were on ventilation for less than 3 days while 49(41.5%) patients had duration of ventilatory support more than 3 days. Patients with acute left ventricular failure 35(29.7%) had high mortality (p<0.01), followed by patients 12(10.2%) with arrhythmias (p=0.46) then DCM 11(9.3%). Association between ventilation time and outcome of the patients exhibited that patients who were on ventilation for less than 3 days had higher survival(36(30.5%) vs 33(28.0%) p=0.02)as compared to patients with ventilatory support for more than 3 days (34(28.8%) vs 15(12.7) p=0.02).
Conclusion: Our study results yielded that underlying etiologies, co-morbidities and duration of ventilation stay affect significantly on the outcome of the patients on ventilation in coronary care unit.
Keywords: Arrhythmias, Left ventricular failure, Myocardial infarction, Ventilatory support.
The role of the coronary care units (CCU) have evolved markedly from a purely an observational unit dedicated to the monitoring and prompt resuscitation of patients with myocardial infarction, to a unit treating an increasingly aging population with complex cardiac conditions and concomitant non-cardiac comorbidities1,2. Patients admitted to the coronary care units present with a variety of conditions, including complicated myocardial infarction, acute heart failure, arrhythmias, and complications of adult congenital heart disease3. Advances in early coronary intervention are reflected in decreasing rates of patients admitted with ST elevation myocardial infarction to the coronary care unit2. However, there is an increase in the prevalence of non-cardiac critical illness, such as respiratory failure, sepsis, and acute kidney injury4.
This new paradigm has led to an increase in the number of patients requiring ventilation and with a longer duration of this therapy during their CCU stays5. A deep understanding of respiratory physiology and the interactions between the cardiovascular and respiratory systems is essential for managing patients requiring ventilation in the coronary care unit1,6.Congestive cardiac failure, pulmonary edema and severe cardiogenic shock are common indications for ventilatory support in the coronary care unit3,7.The choice of ventilation modes should be tailored to the specific patient's condition, ensuring effective ventilation, reducing the work of breathing and minimizing adverse hemodynamic effects8.Discontinuation of mechanical ventilation should be considered as soon as the cardiac pathology that prompted the initiation of respiratory support, is stabilized6.
Table-I: Showing descriptive statistics of the patients.
< 40 years###26(22.0%)
Acute Left Ventricular Failure due to Myocardial Infarction###59 (50.0%)
Pulmonary Edema due to Mitral Stenosis/Mitral Regurgitation###15 (12.7%)
Respiratory (COPD + Pneumonia)
Arrhythmias (Recurrent VT/VF and fast AF)###8 (6.8%)
Dilated Cardiomyopathy with acute Decompensation###20 (16.9%)
Ventilation time in days
<3 days###69 (58.5%)
3 days###49 (41.5%)
LVEF(Left Ventricular Ejection Fraction)
Length of Hospital Stay
<7 days###50 (42.4%)
7 days###68 (57.6%)
CPR Done before putting on Ventilation###35 (29.7%)
Raised Serum Urea/Creatinine###26 (22.0%)
Increased TLC (Total Leukocyte Count)###15 (12.7%)
Table-II: Association between duration of ventilation and underlying etiology with outcome.
Acute Left Ventricular Failure due to###35(29.7%)###24(20.3%)###< 0.01
Pulmonary Edema due to Mitral###7(5.9%)###8(6.8%)###0.27
Arrhythmias (Recurrent VT/VF, Fast###12(10.2%)###8(6.8%)###0.46
Dilated Cardiomyopathy with acute###11(9.3%)###5(4.2%)###0.03
Ventilation time in days
< 3 days###33(28.0%)###36(30.5%)###0.02
Most patients undergoing mechanical ventilation in coronary care unit can be quickly removed provided the condition responsible for establishing the ventilation has been treatedor stabilized9. The unnecessary prolongation of this process can result in increased hospital costs and complications associated with it10. It is well established that 5% to 30% of patients undergoing ventilation are difficult to wean mainly because of underlying severe coronary artery disease complicated by myocardial infarction, previous pulmonary diseases, prolonged mechanical ventilation times, multiple organ dysfunctions and debilitating neurological diseases11. The effects of ventilation in patients with ischemic heart disease are complex and depend upon a number of variables especially the patient's volume status, the role of right and left ventricles, after loads, lung functional status and chest and abdominal compliance8.
These patients require special precautions for ventilatory, nutritional, haemodynamic and inotropic support. Many of these patients have ventricular dysfunction, pulmonary congestion, haemodynamic instability, myocardial ischemia or use of vasoactive drugs all of which can contribute to the weaning failure and prolonged dependence on ventilator12. The weaning process can significantly stress the cardiovascular system and cardiac failure is a common cause of failure to wean13. The identification of patients more likely for failure to wean and prompt preemptive intervention is crucial for successful weaning and avoiding complications related to prolonged mechanical ventilation1,14.
Outcome of the patients on ventilatory support is multi-factorial in origin. The outcome of cardiac patients receivingventilation in coronary care unit for particular indications has been studied, but the association of duration of ventilatory support and underlying etiology with outcome has not been studied very often.
MATERIAL AND METHODS
Acomparative cross-sectional study was conducted atCoronary Care Unit (CCU-1) of Armed Forces Institute of Cardiology and National Institute of Heart Diseases, Rawalpindi. Study was carried out from 1st January 2016 till 31st December 2016.All the patients who underwent ventilatory support in coronary care unit during our study period were included usingconsecutivesampling. Data collection tool having different demographic and clinical variables related with ventilatorysupport was used. Data was collected on daily basis in CCU-1 and was entered into the computer on the same day to maintain the quality. SPSS-22 was used to enter and analyze the data.
There were 118 patients who underwent ventilatory support in coronary care unit-1 during our study time period. The mean age of the patients was 61.2+-4.8 years. Greater number of patients were above 40 years of age 92(78.0%). Male patients were more in number i.e 73(61.9%) as compared to females i.e 45(38.1%). The most frequent etiology for ventilation was acute left ventricular failure (LVF) due to myocardial infarction 59 (50.2%), followed by arrhythmias which included recurrent ventricular tachycardia (VT)/ventricular fibrillations (VF) and fast atrial fibrillations 20 (16.9%)(table-I).
Out of all the patients, 69(58.5%) patients were on ventilation for less than 3 days while 49(41.5%) patients had duration of ventilatory support more than 3 days. Majority of patients had left ventricular ejection fraction (LVEF) less than 40%, 78(66.1%). Cardiopulmonary resuscitation (CPR) was performed on 35(29.7%) patients before putting them on ventilation. Co-morbid diseases of the patients (figure).
Chi-square test was applied to find out the association between ventilation time and underlying etiology with the outcome of the patients. Results showed that patients with acute left ventricular failure had highest mortality (35(29.7%) vs 24(20.3%) p96 hours) had higher mortality as compared to patients with shorter duration of ventilation. Our results were also in accordance with other previous studies6,12,15.
Our study results exhibited that underlying etiologies, co-morbidities and duration of ventilation stay affect significantly on the outcome of the patients on ventilation in coronary care unit. Particular attention towards adverse outcome predictors, reduction of coronary ischaemia, co-morbids, control of infection and use of standardized weaning protocol can improve the survival of the patients.
We acknowledge the cooperation of whole CCU-1 staff and specially Dr. Fiaza Noor resident Internal Medicine, without whom the project could not have been completed.
CONFLICT OF INTEREST
This study has no conflict of interest to declare by any author.
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|Publication:||Pakistan Armed Forces Medical Journal|
|Date:||Apr 30, 2017|
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