Acid–base abnormalities (arterial blood gas [ABG]) pose a threat to survival in intensive care unit (ICU) patients. We present a case series of 60 cases from hospital records highlighting the acid–base abnormalities among ICU patients. All standard protocols were followed in the study hospital to collect the arterial blood samples and standard procedures for measurement of ABGs. We found that 93.3% had acid–base abnormalities, 13.3% had nonanion gap metabolic acidosis, 20% had anion gap metabolic acidosis, 50% had metabolic alkalosis, 45% had respiratory acidosis, 21.7% had respiratory alkalosis, 41.7% had mixed disorders, 31.7% had double disorders, and 10% had triple disorder. We conclude that mixed disorder is common in ICU patients with alkalosis being slightly more common than acidosis. By doing ABG, we will be able to detect the underlying acid–base disorder promptly and initiate treatment immediately so that we can decrease the suffering and save the lives of the patients. Hence, a careful look at the ABG within 24 h of admission of a patient to ICU can help save lives.
Keywords: Acid–base abnormalities, arterial blood gas, diagnosis, metabolic alkalosis, mixed disorder
|How to cite this URL:|
Mallela VR, Alam KC, Pendurthi AK, Manjula B S. Acid–base abnormalities among patients admitted in the intensive care unit of a teaching hospital. APIK J Int Med [Epub ahead of print] [cited 2022 Sep 25]. Available from: https://www.ajim.in/preprintarticle.asp?id=353257
| Introduction|| |
There is a fine balance of acid and bases in the human blood. This balance is responsible for the smooth functioning of the body. Healthy cellular functioning is dependent on the acid–base balance. Acid–base disorders result due to disturbances in this acid–base balance. They may be associated with increased morbidity and mortality.,
The acid–base disorder can be diagnosed by measuring blood gases in the arteries and plasma electrolytes. They also help in the evaluation of the respiratory and metabolic functions (pCO2, pH, and pO2). Early diagnosis using the arterial blood gas (ABG) analysis acts as an indicator which helps in deciding the line of treatment in critically ill cases. It also helps in providing the clue about the seriousness of the cases.
The present study was carried out to describe the extent of acid–base abnormalities in patients admitted to the intensive care unit (ICU) of a teaching hospital
| Methods|| |
This was hospital-based case series on acid–base abnormalities among 60 patients admitted to the ICU from June 2021 to August 2021. The study was carried out in the ICU of General Medicine Department of Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad, India.
This was a hospital record-based study, and we did not use any identifying information of the patients, and hence, Institution Ethics Committee permission was not sought. All patients of age group of 18 years and older admitted to ICU during the study period of either gender were included in the study, and cases not consenting and where arterial blood sample was not available were excluded from the study.
Baseline demographic characteristics such as age, sex, residence, alcohol use, and clinical features were recorded in the predesigned semi-structured study questionnaire. Blood pressure, 12-lead electrocardiogram (ECG), and chest X-ray findings were noted down, and COVID-19 status was assessed (reverse transcription–polymerase chain reaction test or past report).
In the present study, the radial artery was the most preferred site for blood collection as it is accessible and comfortable for the patient than the other alternate sites. The radial artery is best palpated between the distal radius and the tendon of flexor carpi radialis when the wrist is extended. Following sterile precautions, one or two fingers are used to gently palpate the artery while holding the needle in the other hand. The artery is then punctured with the needle at 30°–45° angle relative to the skin. A preheparinized syringe was used, and around 1 ml of blood was taken. The needle was then removed while simultaneously applying pressure to the puncture site with sterile gauze until hemostasis is achieved. The collected blood was sent for the analysis.
Blood urea was measured using BeneSphera Urea UV system pack liquid stable reagent used with Mindray BS-360 analyzer. A sample volume of 3 μl of blood was used. It employs the principle of GLDH method. Serum creatinine was measured using modified Jaffe reaction. Blood glucose was measured by the glucose oxidase method peroxidase method. Serum electrolytes, sodium, potassium, chloride, and bicarbonate were measured by Sensa Core ST-200 Pro Electrolyte Analyzer. The principle is based on ion-selective electrodes. ABG analysis was done using ST-200 CC Blood Gas Analyzer. It employs the principle of ion-selective electrode, impedance, and amperometry. It requires a sample volume of 150 μl of blood taken from an artery.
| Results|| |
The majority of study participants were in the age group of 18–29 years (23.3%), followed by 50–59 years (20%). Males were more than females (53.3% vs. 46.7%), and 80% were from urban areas. About 13.3% used alcohol. The most common clinical feature was vomiting in 36.7% of the cases, followed by shortness of breath in 31.7% of cases [Table 1].
|Table 1: Distribution of study subjects as per demographic and clinical characteristics|
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Twenty-five percent had high blood pressure, and 33.3% had normal ECG. The most common ECG abnormality was tachycardia in 43.3% of cases. About 31.7% had abnormal chest X-ray findings and 4 were COVID-19 positive [Table 2].
Only 6.7% had normal ABG. The most common acid–base abnormality was metabolic alkalosis (50%), followed by respiratory alkalosis in 41.7% of cases. About 10% had triple disorder while 31.7% had double and 41.7% had mixed disorder. Twenty cases exhibited acidosis [Table 3].
| Discussion|| |
The 93.3% of the cases had acid–base abnormalities which is higher compared to one study which reported it as 62.8% as their study sample was 1144 compared to 60 in the present study and another reason for lower incidence may be due to their patients also included from emergency department, ICU, and general wards. The incidence in another study was also lower at 56% where they studied only 110 patients but in the general ward patients. However, it was found to be higher in another study at 71% which included patients with all complaints above the age of 18 years which is similar to the present study.
We found that 41.7% had mixed disorder which was slightly lower than reported in the previous study of 53.8%, and it was 55.4% from another study, but it was reported as only 6.5% from one study.
Respiratory alkalosis was seen in 45% of the cases in the present study which was comparable to 40.4% from one study. It was reported as only 10% in one study and 22.2% from one more study.
Sotirakopoulos et al. studied 210 cases with diabetes. The incidence of acid–base disorder was 83.8% and this high incidence may be attributed to the presence of diabetes. They compared it with renal function and concluded that in diabetics, the acid–base disorders were common irrespective of renal function.
Hodgkin et al. analyzed 13,430 samples and found that 51% of the cases had metabolic alkalemia, 29% had respiratory alkalemia, 27% had respiratory acidemia, and 12% had metabolic acidemia.
Schrauben SJ et al. reviewed records of 9799 patients, out of which 851 were selected for their study. About 64% had metabolic acidosis. Mortality was more in this group (45%) compared to patients without metabolic acidosis (25%). On subclassification, the mortality was highest in lactic acidosis group, i.e., 56%.
| Conclusion|| |
We conclude that mixed disorder is common in patients with alkalosis being slightly more common than acidosis. By doing ABG, we will be able to detect the underlying acid–base disorder promptly and initiate treatment immediately so that we can decrease the suffering and save the lives of the patients. Hence, a careful look at the ABG within 24 h of admission of a patient to ICU can help save lives.
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Conflicts of interest
There are no conflicts of interest.
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Amith Kumar Pendurthi,
Department of General Medicine, Malla Reddy Institute of Medical Sciences, Suraram, Hyderabad, Telangana
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3]