,, * ** ** = Ab s t r ac t = Compa r a t i v e An a l y s i s o f a r t e r i a l Ga s e s a nd Ac i d - b a s e s t a t u s i n Pa t i e n t s wi t h Cong e n i t a l a nd Ac qu i r e d He a r t Di s e a s e a t Pr e o pe r a t i v e Pe r i o d, Dur i ng Ex t r a c o r p o r e a l Ci r c u l a t i on, a nd Po s t op e r a t i v e Pe r i o d Dong Seok Lee, M. D. *, Bong Keun Lee, M. D. **, Song Myung Ki m, M. D. ** Background: Patients with cardiac diseases who have structural defects in their heart bring about metabolic insult such as preoperative acid-base imbalance. Cardiac operation requires many nonphysiologic procedures such as extracorporeal circulation, hypothermia, and hemodilution. We studied the acid-base status of surgical heart diseases pre-operatively, during extracorporeal circulation, and post-operatively and researched the treatment indications of acid-base disturbances. Material and M ethod: From January 1997 to May 1999, fifty two cases of open heart surgery were carried out under extracorporeal circulation, which divided into a set of pediatric and adult groups, congenital and acquired groups, non-cyanotic and cyanotic groups, The -stat arterial blood gas analysis was done in each group during the preoperative period, during the operation with extracorporeal circulation, and during the postoperative period. Result: Before surgery, all patients present metabolic acidosis, PaO2 was low in adult group and acquired group and compensatory respiratory alkalosis was noted in cyanotic group. During extracorporeal circulation, adult group revealed alkalosis and normal in acquired group. Pediatric group presents low PaCO2, metabolic acidosis and respiratory alkalosis. Congenital group and non-cyanotic group showed non-compensatory alkalosis trend and non-compensatory respiratory acidosis were observed in cyanotic group during extracorporeal circulation. Postoperative acid-base status of adult group was recovered to normal and the standard bicarbonate was increased in the acquired group. All of the pediatric, congenital non-cyanotic, and cyanotic groups revealed the lack of buffer base. Conclusion: In Preoperative period, correction of metabolic acidosis was required in pediatric, congenital and non-cyanotic groups, while treatment of metabolic acidosis and low PaCO2 were required in adult and acquired groups. In the cyanotic group, metabolic acidosis * Department of Internal Medicine, Saint Mary Hospital, Busan ** Department of Thoracic and Cardiovascular Surgery, Kosin University, Gospel hospital, Busan : 2001 6 29 : 2001 9 19 : (602-702) 34,. (Tel) 051-990-6466, (Fax) 051-248-9407 E-mail: csksmmd @kosinmed.or.kr. 831
,, 2001:34:831-42 and respiratory alkalosis needed to be corrected preoperatively. Using the extracorporeal circulation, minimal correction was required except acquired group which showed normal acid-base balance. In postoperative period, restriction of bicarbonate was required for acquired group while increase of buffer base was required for pediatric, congenital, non-cyanotic, and cyanotic groups. (Korean Thorac Cardiovasc Surg 2001;34:831-42) Ke y wo rds : 1. Heart diseases 2. Blood gas analysis 3. Acid-base balance,, 1 5).,,.. shear 6)..,. 1997 Hatherill 2).,,,. Ta ble 1. Patie nt profile Number of cases 35 17 Acyanotic 27 Cyanotic 8 Gender Male : Female 3 : 4 10 : 7 Age(Years) Mean 16.8 18.3 43.7 10.0 Range 4/ 12~32 23~61 Children<15yrs Adult>15yrs Number of cases 21 31 Acyanotic 13 31 Cyanotic 8 0 Gender Male : Female 11 : 10 14 : 17 Age(Years) Mean 2.6 3.2 40.8 10.4 Range 4/ 12~32 23~61 1997 1 1999 5 52. 35, 17. 35 27 8. 3 : 4, 10 : 7. 16.8 18.3 152 43.7 10.0 23 61 (Table 1,2). 15. 21 13 8, 31 832
2001;34:831-42,, Ta ble 2. Diagnosis of congenita l heart disease. Acyanotic 27 Diagnosis (No of cases) < 15-Y-0 > 15-Y-0 ASD 3 6 VSD 8 3 VSD, COA 1 ASD, VSD 2 AVSD 1 1 VSD, MR 1 Cor triatriatum, MSR 1 Ta ble 3. Diagnosis and surgical procedures of acquired heart diseases. Diagnosis of acquired heat diseases Valvular heart diseases operation procedure Valve replacement and/or Valvuloplasty No. of cases coronary heart diseases CABG.* Myxoma Excision 1 Total 18 *CABG, Coronary artery bypass graft. 16 DORV, PS 3 Cyanotic 8 TOF 2 TGA 2 Single Ventricle 1 Total 22 13 *ASD, atrial septal defect; VSD, Ventricular septal defect; COA, coarctation of aorta; AVSD, atrioventricular septal defect; MR, mitral regurgitation; MSR, mitral stenoregurgitation; PS, Pulmonic stenosis; DORV, Double outlet right ventricle; TOF, Tetralogy of Fallot; TGA, Transposition of great arteries; Fig. 1. Changes of PaO2 in children a nd adult heart disease at pre- op, ECC and post operative periods. 11 : 10 7 : 8 (Table 1). 2.6 3.2 413, 40.8 10.4 23 61. 14 3, 8, 2 1. 8 2 1. 13 6, 3, 1,, 1. (Table 2). 18 16 1 1 (Table 3). (Fig. 1) Allen's test heparinized syringe. data. 1 2 ml. 833
,, 2001:34:831-42 Ta ble 4. Extracorporeal circulation techniques Pump : Sarn's roller pump. model 3,000 Oxygenator : Hemodilution : 30% Flow rate : 2.4 L/min/m 2 Hypothermia : Bypass time(minutes) : ACC time(minutes) : COBE's membrane oxygenator Congenital Acquired Congenital Acquired Congenital Acquired acyanotic cyanotic Ta ble 5. Composition of pe rfusate Whole blood : Hartmann's solution : Mannitol(15%) : Calcium chloride : Sodium bicarbonate : Albumin (20%) : acyanotic cyanotic acyanotic cyanotic 200ml(children) 600 800ml(adult) 6ml/kg 28 25 25 103.1 56.92 95 39.04 159 76.18 191.9 97.60 53.5 35.72 53.9 32.66 88 44.09 106.5 43.48 10ml in W.B 1 pint+bw 1.2 15ml(under 10 kg) 30ml(10-20 kg) Heparin : 30mg/ 1pint W.B Dexamethasone : Epsilon aminocaproic acid : 1mg/kg Hemofilter(Asai,Japan) in children. Table 4,5.,. 1 4 L/min.. (Blood gas analyzer, CIBA- CORNING 845, USA CHIRON DIAGNOSTICS 348, USA) -stat 7,8) (PaO2), (PaCO2) ph actual bicarbonate ( HCO3 ) base excess. CO2 content CO2 capacity monogram buffer base standard bicarbonate Siggaard- Andersen monogram. data. SPSS version 9.0 unpaired Student-t ANOVA P 0.05. 1), 73mmHg 500.6mmHg 263mmHg. (p=0.013) 63.8mmHg(p=0.003) (Fig. 1). (Fig. 2). (Fig. 3). 2) 73 23.37 mmhg, ph 7.39 0.04, 35.5 5.29 mmhg, actual bicarbonate 21.3 834
2001;34:831-42,, Fig. 2. Changes of PaO2 in congenital and acquired hea rt disease at pre- op, ECC a nd post operative periods F ig. 3. Changes of PaO2 in acyanotic and cya notic heart diseases at pre- op, ECC a nd post operative periods 2.49 meq/l base excess -2.72 1.92 meq/l. CO2 content 22.4 2.6 meq/l, CO2 capacity 23.1 1.73mEq/L, buffer base 50 10.76mEq/L, bicarbonate 21.9 1.48 meq/l. 508.6 130.98 mmhg., ph 7.44 0.07, 34.8 6.87 mmhg actual bicarbonate 22.59 3.61mEq/L, base excess 0.71 3.2mEq/L. content 23.57 3.65mEq/L CO2 capacity 24.7 2.75mEq/L,. buffer base 45.37 14.69 meq/l bicarbonate 23.41 2.66mEq/L. 263 96.85 mmhg ph 7.41 0.04, 38.9 4.63mmHg, base excess 0.34 2.55 meq/l, actual bicarbonate 23.97 2.54 meq/l. CO2 content CO2 capacity 25.14 2.64 meq/l 25.3 2.23 meq/lbuffer base 37.49 12.79 meq/l bicarbonate 23.48 2.40 meq/l buffer base (Table 6). 3) 88.2 15.53 mmhg., ph 7.42 0.02, 34.9 5.21mmHg actual bicarbonate 22.19 3.26mEq/L, base excess 1.50 3.24 meq/l. CO2 content CO2 capacity 23.24 3.41mEq/L 24.13 2.33mEq/L CO2 Ta ble 6. Acid- base status betwee n conge nital and acquired heart diseases PH PaCO2 [HCO3] B.E. CaCO2 CO2 Capaity B.B. S.B Pre-op 7.40 0.03 35.86 4.45 21.99 2.30-1.96 2.03 23.1 2.40 23.7 1.74 48.5 12.95 22.3 1.36 CHD Bypass 7.45 0.06 33.83 6.53 23.02 3.25-0.03 2.92 24.0 3.33 25.3 2.48 46.9 12.63 23.9 3.03 Post-op 7.41 0.05 39.20 5.37 24.49 3.54-0.10 2.92 25.7 3.63 25.7 2.82 41.3 15.06 23.6 3.03 Pre-op 7.42 0.03 33.76 6.40 21.5 4.10-2.1 4.09 22.5 4.28 23.7 2.87 45.9 12.83 22.3 3.30 AHD Bypass 7.45 0.08 37.34 7.25 25.0 2.22 1.8 2.24 26.2 2.34 26.6 2.05 47.7 11.33 25.7 2.13 Post-op 7.42 0.05 41.33 4.50 26.31 2.54 1.96 3.05 27.6 2.58 27.2 2.49 44.6 16.03 27.2 4.62 B.E., Base Excess; B.B., Buffer Base; S.B., Standard Bicarbonate 835
,, 2001:34:831-42 content buffer base 46.03 14.01mEq/L bicarbonate 22.57 2.50 meq/l. alveolar hyperventilation. 544.7 79.97mmHg., PH 7.46 0.07, 35.1 7.04 mmhg actual bicarbonate base excess 24.4 2.48 meq/l -1.4 2.21mEq/L. CO2 content CO2 capacity25.47 2.63mEq/L 26.43 1.9 meq/lbuffer base 48.47 10.08 meq/l. bicarbonate 25.19 2.03mEq/L. 199.2 51.28mmHg. ph 7.41 0.06, 40.6 5.45 mmhg actual bicarbonate 25.84 3.62 meq/l, base excess 1.19 3.31mEq/L. CO2 content CO2 capacity27.06 3.69 meq/l 26.76 3.06mEq/L, bicarbonate 25.61 4.59 meq/l buffer base 45.14 16.15 meq/l (Table 6). 4) (p=0.013). (p=0.003).,. ph.,, (Table 7). 5) ph 7.40 0.03, 35.86 4.45mmHg, actual bicarbonate 21.99 2.30mEq/L, base excess -1.96 2.03mEq/L. CO2 content CO2 capacity 23.1 2.40mEq/L 23.7 1.74mEq/L. buffer base bicarbonate 48.5 12.95mEq/L 22.3 1.36mEq/L. ph 7.45 0.06 33.83 6.53mmHg. actual bicarbonate base excess 23.02 3.25 meq/l -0.03 2.92 meq/l. CO2 meq/l, CO2 content 24.0 3.33 capacity 25.3 2.48mEq/L, buffer base 46.9 12.63mEq/L bicarbonate 23.9 3.03 meq/l. Ta ble 7. Comparison of acid- base status between children and adult heart diseases. Groups Status of PO2 and PCO2 Acid-base status Children heart diseases < 15yrs Pre-op Hypoxemia,mild ECC Hyperoxemia, excessive Hypocarbia, mild Uncompensated respiratory alkalosis metabolic acidosis Post-op Hyperoxemia, high Deficient buffer base Adult heart diseases > 15yrs Pre-op Normoxemia Hypocarbia, mild ECC Hyperoxemia, excessive Alkalosis Post-op Hyperoxemia, high Normal status 836
2001;34:831-42,, Ta ble 8. Acid- base status betwee n conge nital and acquired heart diseases ph PaCO2 (mmhg) [HCO3] B.E. CaCO2 meq/l CO2 Capacity B.B. S.B. Pre-op 7.40(0.03) 35.86(4.45) 21.99(2.30) -1.96(2.03) 23.1(2.40) 23.7(1.74) 48.5(12.95) 22.3(1.36) CHD 35 Bypass 7.45(0.06) 33.83(6.53) 23.02(3.25)* -0.03(2.92)** 24.0(3.33)*** 25.3(2.48) 46.9(12.63) 23.9(3.03) Post-op 7.41(0.05) 39.20(5.37) 24.49(3.54) -0.10(2.92)@ 25.7(3.63) 25.7(2.82) 41.3(15.06) 23.6(3.03) Pre-op 7.42(0.03) 33.76(6.40) 21.5(4.10) -2.1(4.09) 22.5(4.28) 23.7(2.87) 45.9(12.83) 22.3(3.30) AHD 17 Bypass 7.45(0.08) 37.34(7.25) 25.0(2.22)* 1.8(2.24)** 26.2(2.34)*** 26.6(2.05) 47.7(11.33) 25.7(2.13) Post-op 7.42(0.05) 41.33(4.50) 26.31(2.54) 1.96(3.05)@ 27.6(2.58) 27.2(2.49) 44.6(16.03) 27.2(4.62) B.E., Base Excess; B.B., Buffer Base; S.B., Standard Bicarbonate; *, P=0.025; **, P= 0.027; ***, P=0.02; #, P= 0.013;, P= 0.022;, P=0.001 Repeat ANOVA s underline parameters P < 0.05. ph 7.41 0.05, 39.2 5.37 meq/l, actual bicarbonate 24.49 3.54 meq/l base excess 0.1 2.92 meq/l. CO2 content CO2 capacity 25.7 3.63mEq/L 25.7 2.82 meq/l. buffer base 41.3 15.06 bicarbonate 23.6 3.03mEq/L. buffer base (Table 8). 6) ph 7.42 0.03, 33.76 6.40 mmhg, actual bicarbonate 21.5 4.10 meq/l, base excess -2.1 4.09 meq/l. CO2 content CO2 capacity 22.5 4.28mEq/L 23.7 2.87 meq/l. Buffer base 47.7 11.33mEq/L, bicarbonate 25.7 2.13mEq/L... ph 7.42 0.05, 41.33 4.50 mmhg, actual bicarbonate 26.31 2.54 meq/l base excess 1.96 3.05 meq/l. CO2 content CP2 capacity 27.6 2.58mEq/L 27.2 2.49 meq/l. buffer base 44.6 16.3mEq/L bicarbonate 27.2 4.62 meq/l. (Table 8). 7)... buffer base bicarbonate (p=0.001) (Table 9). 8) ph 7.40 0.03, 36.19 4.14 meq/l, actual bicarbonate 22.23 2.04 meq/l base excess 7.8 1.87 meq/l. CO2 content CO2 capacity 23.3 2.14 meq/l 23.9 1.50 meq/l. Buffer base 48.4 14.54 meq/l bicarbonate 22.4 1.19 meq/l.. 837
,, 2001:34:831-42 Ta ble 9. Comparative acid- base status between congenital a nd acquired heart diseases Groups Status of O2 and CO2 Acid-base status CHD AHD Pre-op Normoxia Compensated metabolic acidosis Bypass Hyperoxemia, excessive Uncompensated Hypocarbia, mild respiratory alkalotic tendency Post-op Hyperoxemia, high. Pre-op Bypass Normoxia. Hypocarbia, mild Deficient buffer base. Compensated metabolic acidosis Hyperoxemia, excessivenormal status. Post-op Hyperoxemia, high Excess standard bicarbonate ph 7.47 0.06 33.96 6.47 mmhg, actual bicarbonate 23.79 2.85 meq/l, base excess 0.79 2.60 meq/l. CO2 content, CO2 capacity, buffer basebicarbonate. buffer base 43.5 15.65 meq/l. buffer base (Table 10). 9) ph 7.4 0.04, 34.73 5.53 mmhg, actual bicarbonate 21.17 3.02 meq/l base excess 2.58 2.54 meq/l base CO2 content CO2 capacity 22.22 3.15 meq/l 23.2 2.42 meq/l. buffer basebicarbonate 48.6 5.42 meq/l 22.1 1.93mEq/L.. ph 7.41 0.06. 33.41 7.17 mmhg, actual bicarbonate 20.4 3.33mEq/L, base excess -2.79 2.25 meq/l, CO2 content CO2 capacity 21.4 3.52 meq/l 22.7 2.25 meq/l, buffer basebicarbonate 42.9 15.49 meq/l 21.7 1.78mEq/L.. ph 7.43 0.03, 36.49 3.64 mmhg, actual bicarbonate 23.28 3.15 mmhg, base excess 0.81 3.09 meq/l, CO2 content CO2 capacity 24.38 3.25 meq/l 25.0 2.73mEq/L. buffer base 34.1 10.67 meq/l, bicarbonate 23.2 2.46mEq/L. (Table 10). 10) Ta ble 10. Acid- base status between acyanotic and cyanotic heart diseases PH PaCO2 [HCO3] B.E. CCO2 CO2 capacity B.B. S.B. Acyanotic Pre-op Bypass Post-op 7.4 0.03 36.19 4.14 22.23 2.04-1.78 1.87 7.47 0.06 33.96 6.47 23.79 2.85* 0.79 2.60** 7.40 0.06 40.01 5.58 24.85 3.62 0.11 2.90 23.3 2.14 24.77 2.91*** 26.05 3.70 23.9 1.50 48.4 14.54 22.4 1.19 26.1 1.99 48.2 11.72 24.6 2.16 25.9 2.93 43.5 15.65 23.7 3.22 Cyanotic Pre-op Bypass Post-op 7.40 0.04 7.41 0.06 34.73 5.53 33.41 7.17 21.17 3.02 20.40 3.33* 7.43 0.03 36.49 3.64 23.28 3.15-2.58 2.54-2.79 2.25** -0.81 3.09 22.22 3.15 21.40 3.52*** 24.38 3.25 23.2 2.42 48.6 5.42 22.1 1.93 22.7 2.25 42.9 15.49 21.7 1.78 25.0 2.73 34.1 10.67 23.2 2.46 B.E.,Base Excess; B.B., Buffer Base; S.B., Standard Bicarbonate; *, P= 0.025; **, P= 0.016; ***, P= 0.028; #, P= 0.005; ##, P= 0.014;, P= 0.022;, P= 0.012 Repeat ANOVA s underline parameters P < 0.05 838
2001;34:831-42,, Ta ble 11. Comparative acid- base status between acya notic and cyanotic heart diseases Groups Status of PO2 and PCO2 Acid-base status Acyanotic heart diseases Pre-op Bypass Hyperoxemia, excessive Uncompensated respiratory alkalosis Post-op Hyperoxemia, high Deficient buffer base Pre-op Hypoxemia, moderate Hypocarbia respiratory alkalosis Cyanotic heart diseases Bypass Hyperoxemia, excessive Hypocarbia respiratory alkalosis Post-op Hyperoxemia, high Deficient buffer base. Ta ble 12. Comparative acid- base status of all groups. Groups Pre-op. Bypass Post-op. Children heart diseases Hypocarbia Comp. resp. alk. Comp. meta. acidosis Adult heart diseases Hypocarbia Alkalosis. Congenital heart diseases Uncompensated respiratory alkalotic tendency Deficient buffer base. Normal status Deficient buffer base Acquired heart diseases Hypocarbia Normal status Excess standard bicarbonate Acyanotic heart diseases Uncompensated respiratory alkalosis Deficient buffer base Cyanotic heart diseases Compensated respiratory alkalosis Compensated resp. acidosis meta. alkalosis Deficient buffer base.. buffer base (Table 11). 1960., 7).,.,,.,,.,,, 8,9). 839
,, 2001:34:831-42, 10) 3)., 8),. Hatherill 2). polarographic electrode, Modern Severinghaus electrodes ph Sanz electode. nomogram. actual bicarbonate base excess. CO2 content CO2 capacity Van Slyke Cullen 11).. CO2 content = actual bicarbonate+(pco2 0.03). CO2 capacity ph CO2 content nomogram. actual bicarbonate buffer basebicarbonate Siggaard-Andersen nomogram. CO2 content, CO2 capacity, buffer basebicarbonate. 1980, 37. 25 30. ph stat 12) -stat 13) 2, -stat. ph-stat 1986 Henriksen 14). -stat ph alkalosis O2-Hb, 14).,, -,. (A-a) DO2..,,., buffer,, 3 5 PCO2, 1 2 15). buffer, bicarbonate, 3 15). buffer,, 15). 500 mmhg 30% Pearl 18),,. Pearl ph stat.,,,,,. bicarbonate 840
2001;34:831-42,, bicarbonate..,..,., bicarbonate,,, buffer base. 1. Murkin JM, Farrar JK, Tweed A, Mckenzie FN, Guiraudon G. Cerebral autoregulation and f low/ metabolism coupling during cardiopulmonary bypass : The inf luence of PaCO2. Anesth Analg 1987;66:825-32. 2. Hatherill M, Tibby SM, Durward A, Rajah V, Murdoch IA. Continuous intra-arterial blood-gas monitoring in inf ants and children with cyanotic heart disease. Br J Anaesthesia 1997;79:665-7. 3. Andersen NN, Mendelow M, Olsson GW. Relationship of resp iratory alkalosis to metabolic acidosis during extracoporeal circulation. Surgery 1963;53:730-8. 4. Davies LK. Hypothermia Physiology and clinical use. In: Graclee GP, Davies RF, Utley JR. Cardiopulmonary Bypass Principles and Practice. Baltimore: Williams & Wilkins, 1993;140-9. 5. Jonas RA, Bellinger DC, Rappaport LA, et al. Relation of ph strategy and developmental outcome af ter hypothermic circulation arrest. J Thorac Cardiovasc Surg 1993;106: 362-8. 6. Kirklin JK, Kirklin JW, Pacifico AD. Cardiopulmonary bypass. In: Arciniegas E. ed. Pediatric cardiac surgery. Chicago: Year book medical publishers. 1985;423-31. 7.,,,,,.. 1977;10:250-67. 8. Guilbeau EJ, Moore LK, Viole AJ, et al. Eff ect of intermittent inf usions of glucose-containing crystalloid cardioplegic solution on myocardial tissue lactic acid and recovery of contractility. J Thorac Cardiovasc Surg 1984;87:920-9. 9. Khuri SF, Marston WA, Josa M, Braunwald NS, Cavanaugh AC, Hunt H, Barsamian EM. Observation on 100 patients with continous intraoperative monitoring of intramyocardial ph-the adverse eff ects of ventricular f ibrillation and reperf usion. J Thorac Cardiovasc Surg 1985;89:170-2. 10. Gaensler EA. Resp iratory acidosis as seen f ollowing surgery. Am J Surg 1962;103:289-94. 11. Van Slyke DD, Cullen GE. Studies on acidosis. J Biol Chem 1917;30:289-94. 12. Kurth CD, O'Rourke MM, O'Hara IB. Comparison of ph-stat and alpha-stat cardiopulmonary bypass on cerebral oxygenation and blood f low in relation to hypothermic circulatory arrest in p iglets. Anesthesiology 1998;89:110-8. 13. Hindman BJ. Choice of -stat and ph-stat management and neurologic outcomes af ter cardiac surgery. Anesthesiology 1998;89:5-7. 14. Henriksen J. Brain luxury perf usion during cardiopulmonary bypass in humans. A study of the cerebral blood f low response to changes in CO2, O2 and blood pressure. J Cereb Blood Flow Metab 1986;6:366-71. 15. Reed CC, Stafford TB. Cardiopulmonary bypass. Houston: Texas Medical Press, Inc. 1985;200-8. 16. Casthely PA, Bregman D. Cardiopulmonary bypass : Physiology, Related complications and Pharmacology. New York: Futura Publishing Co. Inc.. Mount Kisco. 1991; 788-97. 17. Tarhan S. Cardiovascular anesthesia and postoperative care. Chicago: Year Book Medical Publishers, Inc.. 1982; 311-9. 18. Pearl JM, Thomas DW, Grist G, Duffy JY, Manning PB. Hyperoxia f or managemnet of acid-base status during deep hypothemia with circulatory arrest. Ann Thorac Surg 2000;70(3):751-5. 841
,, 2001:34:831-42 == :, 5,6,14,16,17).. shear 7).,,. : 1997 1 1999 5 52,,,,, -stat,. :.,....., bicarbonate.,, buffer base. :..,. bicarbonate,,, buffer base. : 1. 2. 3., 842