Waqar Azim, Saadat Parveen, Mahmud Akhtar.
Role of Arterial Blood Gas Analysis in ventilator setting.
Biomedica Jan ;18:34-7.

Arterial blood gas analysis is a very important life saving investigation. It is required in patients on ventilators. It includes pH, pC02 and pO2 as measured value, and bicarbonate as a calculated value. A study was carried out in CMH Multan to assess the role of arterial blood gas analysis (ABG`S) in monitoring the treatment of patients on ventilator. One hundred patients who were put on mechanical ventilation through ventilators in intensive care units were included in the study. Arterial blood was drawn in heparinized syringe, needle was twisted and capped. Lab was informed about gas analyzer calibration and sample was sent for analysis. Two point calibration of blood gas analyzer was done with pH 6.8 & 7.3 calibrators, slope and cal gas calibrators. Quality controls were run before running the test sample. After discarding a few drops of blood test sample was introduced and print outs of the results were obtained. Results were conveyed immediately to treating physician and anaesthetist for ventilator setting and necessary adjustments were made accordingly. Patients suffering from left ventricular failure were 13, bronchial asthma 4, Guillian Barrie syndrome 8, Cerebrovascular accidents 6, Hemiplegia / coma 8, chronic renal failure 5, head/multiple injury 12, pneumonia 7, COPD 8, Septicaemia 4, electric shock 3, diabetes 13, IHD 8 and tetanus 1. Results revealed metabolic acidosis in 13, respiratory acidosis in 11, mixed metabolic and respiratory acidosis in 5, metabolic acidosis and resp. alkalosis in 3, compensated respiratory acidosis in 11, slightly low P02 in 7, metabolic alkalosis in 4, normal ABG`s in 19 and misc results in 22 patients. Patients on ventilator were put on muscle relaxant and his respiratory rate, tidal volume, and oxygen concentration were set on ventilator. It was concluded that as the patient on ventilator is not under control of respiratory centre, ventilator acts as artificial respiratory centre and it needs constant adjustment of parameters like tidal volume, oxygen percentage and peak flow rate according to patients ABG`s status.

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