Introduction
Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) describe clinical syndromes of acute respiratory failure with substantial morbidity and mortality. Even in patients who survive ALI, there is evidence that their long-term quality of life is adversely affected.1 Recent advances have been made in the understanding of the epidemiology, pathogenesis, and treatment of this disease. However, more progress is needed to further reduce mortality and morbidity from ALI and ARDS.2 Because this syndrome of acute respiratory failure is so common in the worldwide, it is fair to say that ALI=ARDS is an unmet medical need. In other words, novel therapies need to be developed to further improve clinical outcomes.3
Multiple risk factors for the development of ARDS have been identified. The sepsis syndrome appears to be the most common, but the overall risk increases with multiple factors. Blood transfusion is an independent risk factor. Advanced age and cigarette smoking are associated with an increased risk of developing ARDS, while alcohol consumption appears to have no influence.4 A review of the 1993 National Mortality Follow Back Study Database determined that the annual ARDS mortality is slowly declining, but that men and blacks have a higher mortality rate compared with women and other racial groups.5
In ARDS, the injured lung is believed to go through three phases: exudative, proliferative, and fibrotic, but the course of each phase and the overall disease progression is variable. In the exudative phase, damage to the alveolar epithelium and vascular endothelium produces leakage of water, protein, and inflammatory and red blood cells into the interstitium and alveolar lumen. These changes are induced by a complex interplay of proinflammatory and anti-inflammatory mediators.6 Type I alveolar cells are irreversibly damaged and the denuded space is replaced by the deposition of proteins, fibrin, and cellular debris, producing hyaline membranes, while injury to the surfactant-producing type II cells contributes to alveolar collapse. In the proliferative phase, type II cells proliferate with some epithelial cell regeneration, fibroblastic reaction, and remodeling. In some patients, this progresses to an irreversible fibrotic phase involving collagen deposition in alveolar, vascular, and interstitial beds with development of microcysts.7
Materials and Methods
This was a prospective, observational and cross-sectional study conducted in the medical ICU of Department of Pulmonology at tertiary care teaching hospital between May 2018 and April 2019. Patients with ALI/ARDS were identified through a prospective daily ICU surveillance, based on the American-European Consensus Conference criteria (AECC).
Inclusion criteria
Patients of either gender above 18 years of age.
Patients with a medical diagnosis leading to ALI/ARDs were included.
Exclusion criteria
Patients with burns, trauma, and postoperative status were excluded.
Patients having contraindication for Pulmonary function test, history of recent myocardial infarction and active hemoptysis were excluded from the study.
Patients with ALI/ARDS were identified based on history, physical examination, chest radiography, and arterial blood gas analysis. All patients had central venous pressure monitoring at admission and echocardiography was performed in all patients during their ICU stay to rule out cardiogenic causes of respiratory distress. Patients were assessed twice during their hospital stay—first, at time of admission and again at the time of discharge from ICU or at the time of death. Baseline characteristics, including comorbidities, history, biochemical and microbiological investigations, and acute physiological, age and chronic health evaluation II (APACHE II) scores, were documented in an Excel sheet. Also, duration of hospital stay, duration of mechanical ventilation, inotrope use, and ultimate hospital outcome were documented at the time of discharge or death.
Results
In our study, we had a total of 59 patient, out of which 43 survived. We had a mortally rate of 27.2%.
Table 1
Distribution of genderbetween alive patients and dead patients
|
Gender |
Alive patients in no. |
Dead patients in no. |
|
Male |
26 |
11 |
|
Female |
17 |
5 |
|
Total |
43 |
100 |
Table 2
Distribution of age groups between alive patients and dead patients
|
Age (in years) |
Alive patients in no. |
Dead patients in no. |
|
<25 |
13 |
2 |
|
25-60 |
23 |
13 |
|
>60 |
7 |
1 |
|
Total |
43 |
100 |
In our study, most of the patients were 25-60 years i.e., 23 out of 43, followed by <25 years, i.e., 23 out of 43 alive patients in number.
Table 3
Smoker and Alcoholic of ARDS/ALI (both survivors and non-survivors)
|
Parameter |
Alive patients in no. |
Dead patients in no. |
|
|
Smoker |
Yes |
4 |
3 |
|
|
No |
39 |
7 |
|
Alcoholic |
Yes |
9 |
7 |
|
|
No |
34 |
3 |
Table 4
Diagnosis of ARDS/ALI (both survivors and non-survivors)
|
Diagnosis |
Alive patients in no. |
Dead patients in no. |
|
Pneumonia |
17 |
9 |
|
Post-operative sepsis |
11 |
3 |
|
Poly trauma |
9 |
3 |
|
Neurological Disorder |
1 |
0 |
|
TB |
1 |
0 |
|
Poisoning |
1 |
0 |
|
Tropical diseases |
3 |
1 |
The risk factors for developing ALI/ARDS were pneumonia (26 patients), postoperative sepsis (14 patients), poly trauma (12 patients), tuberculosis (1 patients), poisoning (1 patients) and neurological disorder (patients).
Table 5
Sign and symptoms of patients with ARDS/ALI (both survivors and non-survivors)
Discussion
The ARDS is a disease with a high mortality and is a common cause of admission into intensive care units (ICUs) all over the world. The American-European Consensus Conference definition of ALI and ARDS was published in 1994. This definition is simple to apply in the clinical setting and also recognizes that the severity of clinical lung injury varies according to the severity of arterial hypoxemia.8
The risk factors for developing ALI/ARDS in our study were Pneumonia (44.06%), Tropical diseases (6.77%), Postoperative sepsis (26.4%), Poly trauma (20.33%), Tuberculosis (1.69%), Poisoning (1.69%) and Neurological disorder (1.69%). In the study by Amato MB et al., the common risk factors for ALI/ARDS were pneumonia (30%), recent surgery in abdomen (10%), septicemia with MOF (18%), and trauma (12%).9 Other significant causes were pancreatitis, thermal burns> 40% (6%), peritonitis, falciparum malaria and poisoning. Similar findings were also find in the studies by Guerin C et al., 10 When compared with the risk factor associated with the non-survivors in our study, it is observed that the most common risk factor is pneumonia and that the incidence of sepsis, poly trauma is quite similar in both the studies however the incidence of tropical diseases is much higher in our study.
The presence of co-morbid conditions also affects the outcome of ALI/ARDS patients. In our study 15% of the patients had respiratory diseases, 7.7% of the patients had hypertension, 6.2% of the patients had diabetes mellitus, 3% of the patients had HIV and 1.5% of the patients had ischemic heart disease. It was observed that 18.5% of the patients used to consume alcohol. However, none of the above factors affected the outcome of the patients significantly. In the study by Cavalcanti AB et al., it was observed that cirrhosis of the liver (20%), HIV infection (10%), active malignancy (24%) and organ transplantation (9%) were the common co-morbid conditions in the patients dying due to ALI/ARDS.11 In the study by Mekontso D et al., 20% of the patients had hypertension, 8% of the patients had diabetes mellitus and 3% of the patients had coronary artery disease.12 The low incidence of the co-morbid conditions like malignancy, HIV infection in our study could represent a lack of awareness and early detection of these conditions in the general population.
An attempt was made to analyze the presenting clinical features of the patient and the impact they had on the outcome. It was observed that most of the patients presented within 10 days of the onset of the symptoms. Dyspnea was present in almost all cases. Fever was seen in majority of patients with duration of 2 to 4 days. History of wading through water was present in 27(73%) cases, this can be attributed to the similar frequency of leptospirosis 22(59.5%) which is water borne infection. 11(29.7%) patients had history of hemoptysis. Duration of cough related with the outcome of disease. Prognosis was better in patients with duration of cough less than 10 days. Hence early detection of symptoms like cough could alter the outcome of the disease.
Systemic abnormalities were found in majority of cases in the form of hematological, renal and liver dysfunction. These finding in our study show similar pattern as in the study carried out by Slutsky AS et al.13 In a study by Caironi P et al., renal and Hematological dysfunction have been shown to be independent predictors of mortality.14 The organisms that were commonly isolated in cultures (blood and sputum) were pseudomonas and Klebsiella. A similar organism’s pattern was seen in patient’s studies by Goligher EC et al.15
A number of studies had found a direct association between poor oxygenation and mortality whereas other studies have failed to identify a correlation.16 When tested prospectively, increasing severity of lung injury (using LIS Score), measured at 24, 48, and 72 hours, wasn’t associated with increased mortality. 17 We also observed that a MODS of >4, LIs >2 and APACHE II >2 had higher association with mortality. The mean score in non-survivors were as follows: MODS 5.3, LIS 2.3 and APACHE II 17.6 these scoring systems were equally effective in predicting mortality in ALI/ARDS due to tropical diseases. The SOFA score was not found to be useful in predicting the outcome. It should be noted that we had used the scores only during assessment of the patients on the first day of admission in our ICU. The mean P/F ratio was 208 in survivors and 167 in non-survivors in our study. However, no significant difference has been found in the P/F ratio in survivors and non-survivors in other studies.18
In our study 60% of the patients required mechanical ventilation. The patients were ventilated using ACMV (Assist control mechanical ventilation) or control mode and a lung protective strategy with tidal volume of 8ml/kg was given with PEEP whenever required. Inverse ratio ventilation and prone pressure ventilation were also attempted in a few cases. The significant finding was that survivors spent lesser number of days (mean 2.74 days) on ventilator than non-survivors (mean 8.73 days). Also 50% of the deaths were within the first 24 hours. In the study by Constantin JM et al., duration of ventilation was less than 7 days in 80% of the patients (dead) while the same was 66% in non-survivors in our study and 71% in survivors.19 The use of steroids in our study did not reduce the mortality as in other studies.20 In the survivors, a PFT was done in 34% of the patients. It was seen that overall 43% has an obstructive and restrictive pattern 28.5% had an obstructive pattern and 28.5% had a normal PFT. It was also seen that none of these patients had preexisting respiratory disease. Mean pO2 on discharge was 81 mm of Hg so a long-term prospective trial is essential to look at the long-term effects of ALI/ARDS patients in the survivors of this condition.
Conclusions
Pneumonia and tropical diseases are the common risk factor for the ARDS/ALI. The presence of co-morbid conditions also affects the outcome of ALI/ARDS patients. MODS of >4, LIs >2 and APACHE II >2 had associated with higher mortality.
Abbreviation
APTT: Activated Partial Thromboplastic time; PT: prothrombin Time; DIC: disseminated intravascular coagulation; P/F: SOFA Score: Sequential Organ Dysfunction Assessment; MODS: Multiple Organ Dysfunction score; LIS: lung injury score; APACHE: Acute Physiology and Chronic Health Evaluation.
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