The use of arterial blood gases in patient management at the Kenyatta national hospital - intensive care unit

Abstract

The role of laboratory tests in patient management in the ICU includes the diagnosisof patients' conditions and their minute to minute management. The varioustests done in the lCU are extensive and expensive, only a few of which are carried out in the lCU support laboratory. Their usefulness depends on their proper selection and subsequent timely adjustments as necessary in the treatment of the patient. lCU care consumes 20% of total hospital charges 37.The high cost of care in the lCU is partly due to the numerous tests ordered by the medical staff. This study which was carried out at the KNH-ICU looked into whether one of these tests, arterial blood gas analysis, was effectively and appropriately being used in the KNH-ICU and what changes can be made in order to optimize it's usefulness while reducing the cost of patient care. A total of one hundred and ninety two ABGs from eighty four patients were analysedover a period of two months. Of these 121 were on ventilatory support. Most samples were obtained from patients who had undergone open-heart surgery (31%). This was also the group that had indwelling arterial cannulae. The indicationsfor ABGswere most commonly to correct abberant ABGs(51%) and to titre oxygen (19%). In the later case, 51% had pulse oximeters in concurrent use. ABG requests were considered inappropriate in 68 (35%) of the cases. The contribution to inappropriately ordered ABGs by requests for electrolyte check could not be quantified although they were noted to have an input. Improperuse of pulse oximetry was evidently a cause for increased number of ABG requests.However, their use would only be safe and useful for patients with SP02 of equal to or more than 95% in whom oxygen was being titred. In conclusion,it is noted that ABGs are being overutilised in KNH-ICU. The ABG requests are often inappropriate, with physician response sometimes being inappropriate.The laboratory, though prompt, was noted to be erratic with regardsto temperature adjustment aspect of ABG measurements. The need for written guidelines is recommended in guiding and standardizing physicians in the request and subsequent followup of ABG reports. Further education of the clinicopathological practitioners in the KNH-ICU laboratory is necessaryin proper use and significance of ABGs. A further longer long-term observational study should then be carried out to ensure that there is an improvementin the use of ABGsat the KNH-ICU.