Pustaka Ilmiah Universitas Padjadjaran

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Pendekatan Stewart Dalam pH Darah Yang Mendasari Asidosis Metabolik (The Stewart’s Approach in Blood pH Underlying Metabolic Acidosis)

Asidosis metabolik merupakan gangguan keseimbangan asam-basa yang paling sering ditemukan di penderita di Intensive Care Unit. Pendekatan yang konvensional berdasarkan hasil ukuran pH, [HC03-], dan base deficit (BD) alat analisis gas darah (AGD) sering tidak sesuai dengan keadaan klinis dan tidak cukup dalam menjelaskan mekanisme yang mendasari asidosis metabolik. Dalam pendekatan Stewart dikemukakan bahwa pH ditentukan oleh strong ion difference (SID), tekanan sebagian karbondioksida (pCO2), kadar asam lemah non-volatil total. Pendekatan ini memberikan pemahaman yang lebih balk tentang mekanisme yang mendasari asidosis metabolik. TUjuan penelitian ini adalah untuk mengetahui kenasaban pH darah hasil ukuran alat AGD dengan perhitungan yang berdasarkan pendekatan Stewart dan mengenali mekanisme yang mendasari asidosis metabolik. Cara yang digunakan adalah penelitian observasional analitik, rancangan potong lintang di 71 penderita asidosis metabolik yang dirawat di ICU pada bulan Juli sampai Agustus 2007. Subjek penelitian diperiksa: pH darah, pCO2, [HCO3 1, BD, ion natrium, kalium, kalsium, magnesium, klorida, laktat, albumin, dan fosfat inorganik. Hasilnya dilaporkan dalam bentuk rerata dan simpangan baku. Data dianalisis menggunakan kenasaban Pearson dan regresi linier ganda. Kemaknaan statistik ditentukan jika nilai p <0,05. Rerata pH hasil ukuran alat AGD dan perhitungan berdasarkan pendekatan Stewart adalah 7,33 (0,11) dan 7,49 (0,11) (r=0,681; p <0,001). Mekanisme yang mendasari asidosis metabolik di subjek penelitian adalah hiperlaktatemia (61,8%) dan hiperkloremia (58,2%). Didasari telitian ini dapat disimpulkan terdapat kenasaban yang kuat dan sangat bermakna antara pH darah hasil ukuran alat AGD dan hasil hitungan berdasarkan pendekatan Stewart. Mekanisme yang mendasari asidosis metabolik penderita yang dirawat di ICU adalah hiperlaktatemia dan hiperkloremia. Metabolic acidosis is the most frequent acid-base disorder in patients of the Intensive Care Unit. By conventional approach based on pH value, [HC03-], and base deficit (BD) from blood gas analyzer (BGA) measurement are often inappropriate with the clinical state and inadequate in explaining the mechanism of the metabolic acidosis. The Stewart approach states that the blood pH is determined by a strong ion difference (SID), the carbon dioxide tension (pCO2), the total concentration of non-volatile weak acid. The Stewart approach may give a better understanding of the mechanisms that underlie the metabolic acidosis. The purpose of this study is to know the correlation of blood pH value measurement from BGA and calculation based on Stewart approach and identifying the mechanisms that underlie a metabolic acidosis. In this study an analytic observational cross-sectional method was used. The examined subjects consisted of 71 patients who were admitted with a metabolic acidosis at the ICU from July up to August 2007 All patients were measured for their blood pH, pCO2, (HCO3 j, BD, sodium, potassium, calcium, magnesium, chloride, lactate, albumin, and phosphate. The result was reported as the mean and standard deviation. The data were analyzed by Pearson's correlation test and linier multiple regression. Statistical significance was determined at p < 0.05. The mean values of blood pH measurement from BGA and blood pH calculation based on the Stewart approach were 733 (0.11) and 749 (0.11) (r = 0.681; p < 0.001). Most patients had two underlying mechanisms of metabolic acidosis. Hyperlactatemia was present in 61.8%, hyperchloremia was present in 58.2% of patients. Based on this study so far, by using the Stewart approach there is an excellent and significant correlation between the blood pH measurement from BGA and blood pH calculation. Hyperlactatemia and hyperchloremia are the main causes of the metabolic acidosis in patients of the ICU ward.