Effect of time delay and storage temperature on blood gas and acid ...

Research in Veterinary Science 76 (2004) 121–127www.elsevier.com/locate/rvsc<strong>Effect</strong> <strong>of</strong> <strong>time</strong> <strong>delay</strong> <strong>and</strong> <strong>storage</strong> <strong>temperature</strong> on blood gas<strong>and</strong> acid–base values <strong>of</strong> bovine venous bloodGurbuz Gokce a, *, Mehmet Citil a , Vehbi Gunes a , Gultekin Atalan ba Department <strong>of</strong> Internal Medicine, Faculty <strong>of</strong> Veterinary Medicine, University <strong>of</strong> Kafkas, Kars 36100, Turkeyb Department <strong>of</strong> Surgery, Faculty <strong>of</strong> Veterinary Medicine, University <strong>of</strong> Kafkas, Kars 36100, TurkeyAccepted 12 August 2003AbstractThe aim <strong>of</strong> this study was to investigate possible changes in the gas composition <strong>and</strong> acid–base values <strong>of</strong> bovine venous bloodsamples stored at different <strong>temperature</strong>s (+4, 22 <strong>and</strong> 37 °C) for up to 48 h. Five healthy cattle were used in the study. A total <strong>of</strong> 15blood samples collected from the animals were allocated into three groups, which were, respectively, then stored in a refrigeratoradjusted to +4 °C (Group I, n ¼ 5), at a room <strong>temperature</strong> <strong>of</strong> about 22 °C (Group II, n ¼ 5) <strong>and</strong> in an incubator adjusted to 37 °C(Group III; n ¼ 5) for up to 48 h. Blood gas <strong>and</strong> acid–base values were analysed at 0 (baseline), 1, 2, 3, 4, 5, 6, 12, 24, 36 <strong>and</strong> 48 h <strong>of</strong><strong>storage</strong>. A significant decrease (p < 0:001) was found, in the pH <strong>of</strong> the refrigerated blood after 5 h <strong>and</strong> its maximum decrease wasrecorded at 48 h as 0.04 unit. There were also significant alterations (p < 0:001) in the blood pH <strong>of</strong> the samples stored at room<strong>temperature</strong> <strong>and</strong> in the incubator after 2 <strong>and</strong> 3 h, respectively. The maximum mean alteration in pCO 2 value for Group I was )0.72kPa during the assessment, while for groups II <strong>and</strong> III, maximum alterations in pCO 2 were detected as +2.68 <strong>and</strong> +4.16 kPa, respectively.Mean pO 2 values increased significantly (p < 0:001) for Group I after 24 h <strong>and</strong> for Group II after 6 h, while a significantdecrease was recorded for Group III after 24 h (p < 0:001). Base excess (BE) <strong>and</strong> bicarbonate (HCO 3 ) fractions decreased significantlyfor all the groups during the study, compared to their baseline values. In conclusion, acid–base values <strong>of</strong> the samplesstored at 22 <strong>and</strong> +4 °C were found to be within normal range <strong>and</strong> could be used for clinical purposes for up to 12 <strong>and</strong> 48 h,respectively, although there were small statistically significant alterations.Ó 2003 Elsevier Ltd. All rights reserved.Keywords: pO 2 ; pCO 2 ; Acid base parameters; Storage <strong>temperature</strong> <strong>time</strong>; Bovine1. IntroductionVarious metabolic <strong>and</strong> respiratory diseases effect venousblood gas composition <strong>and</strong> acid–base values <strong>of</strong>cattle (Radostits et al., 1994; Carlson, 1996). Therefore,accurate measurement <strong>of</strong> these blood values is <strong>of</strong> greatimportance for veterinary clinicians <strong>and</strong> research workers.Human (Paerregaard et al., 1987; Muller-Plathe <strong>and</strong>Heyduck, 1992; Beaulieu et al., 1999) <strong>and</strong> cattle (Poulsen<strong>and</strong> Surynek, 1977; Szenci <strong>and</strong> Besser, 1990; Szenci et al.,1991) blood gas composition <strong>and</strong> acid–base values maychange depending on the type <strong>of</strong> syringe used for sampling,<strong>delay</strong>s in measurement <strong>time</strong> <strong>and</strong> variations in* Corresponding author. Tel.: +90-474-242-6800; fax: +90-474-242-6853.E-mail address: gurbuzgokce90@hotmail.com (G. Gokce).<strong>storage</strong> <strong>temperature</strong>. Continuous anaerobic <strong>and</strong> aerobicmetabolism between the drawing <strong>of</strong> the blood sample <strong>and</strong>its analysis intervals may effect blood acid–base values inhumans (Boink et al., 1991; Liss <strong>and</strong> Payne, 1993), cattle(Jagos et al., 1977; Krokavec et al., 1987; Szenci <strong>and</strong>Besser, 1990) <strong>and</strong> dogs (Haskins, 1977). In vitro bloodmetabolism includes both aerobic metabolism with production<strong>of</strong> carbon dioxide <strong>and</strong> anaerobic glycolysis withproduction <strong>of</strong> non-gaseous acids such as lactic acid. Oxygenconsumption depends on the enzymatic activity <strong>of</strong>the citric acid <strong>and</strong> cytocrome systems in leucocytes<strong>and</strong> reticulocytes <strong>and</strong> will vary with the concentration <strong>of</strong>these cell types. Glycolysis is the predominant metabolicprocess in mature red blood cells. These processes arelargely responsible for the rising <strong>of</strong> pCO 2 in the storedblood <strong>of</strong> dogs (Haskins, 1977), <strong>and</strong> cattle (Poulsen <strong>and</strong>Surynek, 1977). These metabolic changes are <strong>temperature</strong>0034-5288/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.doi:10.1016/j.rvsc.2003.08.009

122 G. Gokce et al. / Research in Veterinary Science 76 (2004) 121–127dependent (Liss <strong>and</strong> Payne, 1993). Additionally, severeleucocytosis (Schimidt <strong>and</strong> Plathe, 1992; Liss <strong>and</strong> Payne,1993) <strong>and</strong> anaemia (Haskins, 1977) can lead to alterationsin acid–base values.Since it is difficult to measure the acid–base <strong>and</strong> gasvalues <strong>of</strong> blood under field conditions in a short period<strong>of</strong> <strong>time</strong> its necessary to store blood (Szenci <strong>and</strong> Besser,1990). Several authors have investigated the alterationsin acid–base variables during the <strong>storage</strong> <strong>of</strong> bloodsamples from humans (Paerregaard et al., 1987; Schimidt<strong>and</strong> Plathe, 1992; Beaulieu et al., 1999), cattle(Jagos et al., 1977; Poulsen <strong>and</strong> Surynek, 1977; Krokavecet al., 1987; Szenci <strong>and</strong> Besser, 1990; Szenci et al.,1991, 1994) <strong>and</strong> dogs (Haskins, 1977). It would be usefulto determine the extent to which changes in blood acid–base values <strong>and</strong> gas composition depend on the duration<strong>and</strong> <strong>temperature</strong> <strong>of</strong> <strong>storage</strong>. To our knowledge, there isno precise information available as to whether or notclinically significant changes occur when bovine venousblood is stored at 22 or at 37 °C for long periods.Therefore, this study was carried out to detect thechanges in gas composition <strong>and</strong> acid–base values inbovine venous blood samples stored at different <strong>temperature</strong>s(+4, 22 <strong>and</strong> 37 °C) for up to 48 h.2. Materials <strong>and</strong> methods2.1. Animals <strong>and</strong> samplingFive clinically healthy, 1–3 years old, crossbreedcattle were used in the study. Following rectal <strong>temperature</strong>measurement, three jugular venous blood sampleswere drawn from each animal into 10 ml plastic syringesthe dead space (0.08 ml) <strong>of</strong> which was filled with heparin(Liquemine Ò -Roche, Istanbul, Turkey). The needle tipswere closed with a rubber stopper after the removal <strong>of</strong>air bubbles from the samples. The samples were placedin a bed <strong>of</strong> crushed ice, taken immediately to the laboratory<strong>and</strong> analysed within 15 min. Following the first(0) hourÕs laboratory analysis, a total <strong>of</strong> 15 blood sampleswere collected from the animals, allocated into threegroups <strong>and</strong> then stored, respectively, in a refrigerator setto +4 °C (Group I, n ¼ 5), at a room <strong>temperature</strong> <strong>of</strong>about 22 °C (Group II, n ¼ 5) <strong>and</strong> in an incubator adjustedto 37 °C (Group III, n ¼ 5), for up to 48 h. Bloodgas <strong>and</strong> acid–base values were analysed at 0, 1, 2, 3, 4, 5,6, 12, 24, 36 <strong>and</strong> 48 h <strong>of</strong> <strong>storage</strong> for all the groups.2.2. Acid–base <strong>and</strong> blood gas analysesThe measurement <strong>of</strong> pH, pO 2 , pCO 2 <strong>and</strong> the calculation<strong>of</strong> st<strong>and</strong>ard Base excess (BEstd), actual base excess(BEact), st<strong>and</strong>ard bicarbonate (stHCO 3 ), actualbicarbonate (actHCO 3 ) concentrations, oxygen saturation(O 2 SAT) <strong>and</strong> oxygen content (O 2 CT) were automaticallyperformed on a blood gas analyser (Chirondiagnostics, Rapidlab 248, UK) prior to the study.Blood samples from the five cattle were analysed forblood gas <strong>and</strong> acid base values four <strong>time</strong>s each within 15min to determine the imprecision <strong>of</strong> parameters, whichemerged as follows: pH 0.01%; pCO 2 1.9%; pO 2 3.52%;ActHCO 3 1.74%; StdHCO 3 1.34%, BEact 1.98%, BEstd1.02%, O 2 SAT 0.39% <strong>and</strong> O 2 CT 1.8% on the basis <strong>of</strong>variation co efficiency. Control <strong>of</strong> accuracy was carriedout using a commercial accuracy control solution(Complete, Bayer, East Walpole, USA). Control valueswere within the normal range as described by the manufacturer.Calculated variables were automatically performedby blood gas analyser according to equations 1programed to device by manufacterer (Chiron diagnostics,Rapidlab 248, UK) The values <strong>of</strong> pH, pCO 2 <strong>and</strong>pO 2 were automatically adjusted to the animalÕs rectal<strong>temperature</strong>s.2.3. Haematological analysesFor the initial haematological examinations, peripheralblood samples were collected from jugular vein intoethylenediaminetetraaceticacid (EDTA) treated tubes.These blood samples were used to manually establishtotal white blood cells (WBCs), total red blood cells(RBCs) <strong>and</strong> haemoglobin concentration (Hb), as describedby Coles (1980).2.4. Statistical analysesThe effect <strong>of</strong> <strong>temperature</strong> on blood gas <strong>and</strong> acid basevalues was tested by analysis <strong>of</strong> variance using SPSS forWindows 6.0. The effects <strong>of</strong> <strong>time</strong> on the repeated measurementswithin each group were also examined usingtwo-way variance analysis (Kirkwood, 1988). The datais presented as mean SE.3. ResultsThe mean initial haematological values <strong>of</strong> the animalsused in the study were detected as 115 0.6 g/l for Hb,5.9 0.5 10 12 cell/l for RBC <strong>and</strong> 6.5 1.9 10 9 cell/lfor WBC. The mean rectal <strong>temperature</strong> <strong>of</strong> the animalswas 38.5 0.2 °C.1 ActHCO 3 ¼ pH þ logðpCO 2 0:0307Þ 6:105; StdHCO 3 ¼ 24:5þ0:9A þðA 2:9Þ 2 ð2:65 þ 0:31ctHbÞ=1000. A ¼ BEstd 0:2½ctHbŠ½100 O 2 SATŠ=100; BEact ¼ cHCO 3 24:8 þ 1:62ðpH 7:40Þ.BEstd ¼ð1 0:014 ctHbÞ½ðcHCO 3 24:8Þ þð1:43 ctHb þ 7:7ÞðpH 7:40Þ.N 4 15N 3 þ 2045N 2 þ 2000NO 2 SAT ¼N 4 15N 3 þ 2400N 2 31100N þ 2:4 10 100:6N ¼ pO 2 þ 10 ½0:48ðpH 7:4Þ 0:0013BEstdŠ <strong>and</strong> BEstd is calculated assuming100% O 2 SAT; O 2 CT ¼ O 2 SAT 1:39 ctHb þ 0:00314 pO 2 .

Table 1<strong>Effect</strong> <strong>of</strong> <strong>storage</strong> <strong>time</strong> on pCO 2 <strong>and</strong> pO 2 <strong>of</strong> bovine venous blood samples stored at +4 °C (Group I), 22 °C (Group II) <strong>and</strong> 37 °C (Group III) (n ¼ 5) (mean SE)Parameter Group Time (h)pCO 2(kPa)I 6.59 0.11abII 6.59 0.11fIII 6.59 0.11e0 1 2 3 4 5 6 12 24 36 48 P15.95 0.09e6.34 0.14f6.20 0.15e5.94 0.10B,e6.60 0.16A,f6.41 0.15A,e5.87 0.12B,e6.59 0.12A,f6.61 0.12A,e6.04 0.10B,de6.81 0.14A,e7.01 0.16A,d6.01 0.11C,e6.88 0.10B,e7.37 0.18A,c6.17 0.10C,cde7.34 0.12B,c9.01 0.26A,b5.86 0.11C,e7.07 0.13B,d8.88 0.29A,b6.34 0.12C,bcd8.06 0.16B,b10.75 -0.32 A,a6.40 0.12B,bc8.82 0.19A,a9.29 0.19A,b6.90 0.10B,a9.27 0.47A,a9.05 0.34A,bp < 0:001p < 0:001p < 0:001P2 p < 0:05 p < 0:01 p < 0:001 p < 0:001 p < 0:001 p < 0:001 p < 0:001 p < 0:001 p < 0:001pO 2 (kPa) I 4.26 0.10dII 4.26 0.10dIII 4.26 0.10a4.27 0.16d4.25 0.10d4.32 0.09a4.47 0.15d4.41 0.15d4.33 0.10a4.55 0.15cd4.64 0.11c4.38 0.12a4.54 0.16d4.57 0.10d4.32 0.11a4.67 0.17bcd4.56 0.11d4.31 0.12a4.77 0.16bcd4.70 0.11c4.31 0.15a4.77 0.18A,bcd4.91 0.11A,b4.08 0.15B,a5.24 0.24A,ab5.00 0.10A,a0.86 0.13B,c5.12 0.24A,abc4.98 0.12A,a1.43 0.41B,b5.42 0.24A,a5.06 0.07A,a0.69 0.04B,cP2 p < 0:01 p < 0:001 p < 0:001 p < 0:001P1, significant differences within group compared to baseline value (a,b,c,d,e,f), (p < 0:001); P2, in each column different letters (A, B, C) indicated significant between groups (p < 0:01),(p < 0:001); pCO 2 , partial pressure <strong>of</strong> carbondioxide (kPa); pO 2 , partial pressure <strong>of</strong> oxygen (kPa).Table 2<strong>Effect</strong> <strong>of</strong> <strong>storage</strong> <strong>time</strong> on O 2 SAT <strong>and</strong> O 2 ct <strong>of</strong> bovine venous blood samples stored at +4 °C (Group I), 22 °C (Group II) <strong>and</strong> 37 °C (Group III) (n ¼ 5) (mean SE)Parameter Group Time (h)0 1 2 3 4 5 6 12 24 36 48 P1O 2 SAT I 62.32 1.20 62.80 2.46 63.28 2.16 64.36 2.04 63.78 2.24 65.46 2.19 66.62 2.09 66.56 2.27 71.52 2.72 69.82 2.89 72.78 2.00 p < 0:05dcdcdbcd cdA,bcd A,abcd A,abcd A,ab A,abc A,aII 62.32 1.20 61.82 1.02 61.33 1.69 64.42 0.34 62.44 1.01 62.06 1.21A62.76 1.18A65.60 1.32A63.88 1.34B60.70 1.88B61.75 0.35Bp > 0:333III 62.32 1.20a61.10 1.42b60.16 1.55b59.30 1.70b57.48 1.82b55.58 2.00B,c51.82 2.30B,c45.54 2.71B,d32.22 0.41C,e8.17 3.38C,f1.85 0.05C,fP2 p < 0:01 p < 0:001 p < 0:001 p < 0:001 p < 0:001 p < 0:001O 2 CT(mmol/l)I 10.16 0.30c10.50 0.44c10.30 0.36c10.46 0.35c10.38 0.38c10.66 0.34A,cII 10.16 0.30 10.08 0.32 10.15 0.42 10.50 0.39 10.18 0.33 10.12 0.35ABIII 10.16 0.30 9.92 0.24 9.80 0.38 9.66 0.33 9.38 0.42 9.08 0.39aaaabB,b10.84 0.36A,c10.22 0.35A8.44 0.46B,c10.86 0.37A,c10.70 0.39A7.44 0.50B,c11.66 0.51A,b10.44 0.39B0.48 0.11C,d11.16 0.40A,c9.92 0.49A1.40 0.60B,d12.00 0.30A,a10.45 0.05B0.3 0.00C,dP2 p < 0:05 p < 0:01 p < 0:001 p < 0:001 p < 0:001 p < 0:001P1, significant differences within group compared to baseline value (a,b,c,d,e,f), (p < 0:05, p < 0:001); P2, in each column different letters (A, B, C) indicated significant between groups (p < 0:05,p < 0:01, p < 0:001); O 2 SAT, oxyhaemoglobin saturation (%); O 2 CT, oxygen content (mmol/l).p < 0:001p < 0:001p < 0:001p < 0:001p < 0:05p > 0:954p < 0:001G. Gokce et al. / Research in Veterinary Science 76 (2004) 121–127 123

Table 3<strong>Effect</strong> <strong>of</strong> <strong>storage</strong> <strong>time</strong> on ActHCO 3 <strong>and</strong> StdHCO 3 <strong>of</strong> bovine venous blood samples stored at +4 °C (Group I), 22 °C (Group II) <strong>and</strong> 37 °C (Group III) (n ¼ 5) (mean SE)Parameter Group Time (h)0 1 2 3 4 5 6 12 24 36 48 P1ActHCO 3 I 31.38 0.35 29.04 0.27 28.00 0.30 27.62 0.40 28.12 0.34 27.88 0.33 28.42 0.43 26.90 0.31 28.74 0.31 28.56 0.54 30.20 0.29 p < 0:001(mmol/l)aB,c B,cde B,de B,cd C,cde B,cd eB,cd B,cd A,bII 31.38 0.35 30.32 0.37A30.38 0.30A29.94 0.49A30.00 0.35A30.00 0.20A30.88 0.63A29.44 0.40 31.20 0.52A30.24 0.29A30.55 0.35Bp > 0:056III 31.38 0.35a28.94 0.26B,c28.88 0.32B,c28.48 0.39B,d29.02 0.37AB,c29.00 0.35B,c31.44 0.48A,a28.08 0.39e29.80 0.36B,b27.57 0.15B,e26.85 0.85B,eP2 p < 0:05 p < 0:001 p < 0:01 p < 0:01 p < 0:01 p < 0:01 p < 0:001 p < 0:01 p < 0:01StdHCO 3(mmol/l)I 29.24 0.29aII 29.24 0.29aIII 29.24 0.29a26.42 0.97cd28.28 0.27b27.46 0.31b26.40 0.26B,cd28.15 0.15A,b26.68 0.28B,c26.32 0.27B,cd27.80 0.40A,c26.18 0.28B,c26.88 0.20A,bc27.54 0.26A,c26.08 0.31B,c26.40 0.22B,cd27.46 0.15A,c26.36 0.44B,c26.80 0.36bcd27.88 0.52c26.58 0.27c25.58 0.20A,d27.74 0.38A,c23.24 0.28B,d27.00 0.24A,bc27.36 0.51A,c22.60 0.20B,e27.30 0.20A,bc25.70 0.38B,d21.67 0.23C,f27.78 0.29A,b25.55 0.75A,d21.05 0.75B,fP2 p < 0:01 p < 0:01 p < 0:01 p < 0:05 p < 0:001 p < 0:001 p < 0:001 p < 0:001P1, significant differences within group compared to baseline value (a,b,c,d,e,f), (p < 0:05, p < 0:01, p < 0:001); P2, in each column different letters (A, B, C) indicated significant between groups(p < 0:05, p < 0:01, p < 0:001); ActHCO 3 , actual bicarbonate concentrations (mmol/l); StdHCO 3 , st<strong>and</strong>ard bicarbonate concentrations (mmol/l).Table 4<strong>Effect</strong> <strong>of</strong> <strong>storage</strong> <strong>time</strong> on BEact <strong>and</strong> BEstd <strong>of</strong> bovine venous blood samples stored at +4 °C (Group I), 22 °C (Group II) <strong>and</strong> 37 °C (Group III) (n ¼ 5) (mean SE)Parameter Group Time (h)0 1 2 3 4 5 6 12 24 36 48 P1BEact I 7.04 0.39 4.74 0.32 3.58 0.35 3.2 00.42 3.64 0.36 3.32 0.35 3.86 0.49 2.24 0.31 4.06 0.31 3.76 0.57 5.24 0.34 p < 0:001(mmol/l)aB,bc B,cd B,de B,cd B,de cd A,eA,cd A,cd A,bII 7.04 0.39a5.90 0.36A,b5.83 0.22A,b5.30 0.52A,c5.14 0.35A,c5.04 0.23A,c5.70 0.70b4.16 0.45A,d5.34 0.61A,c3.58 0.46A,d3.65 0.75A,dp < 0:001III 7.04 0.39a4.44 0.22B,c4.14 0.31B,c3.46 0.43B,c3.68 0.36B,c3.30 0.33B,c4.94 0.44b0.88 0.39B,e1.64 0.39B,d)0.13 0.32B,f)0.85 0.85B,fp < 0:001p < 0:001n.sp < 0:001p < 0:001124 G. Gokce et al. / Research in Veterinary Science 76 (2004) 121–127P2 p < 0:05 p < 0:01 p < 0:05 p < 0:05 p < 0:01 p < 0:001 p < 0:001 p < 0:01 p < 0:001BEstd(mmol/l)I 6.12 0.34aII 6.12 0.34aIII 6.12 0.34a4.16 0.26B,bc5.10 0.31A,b3.86 0.16B,b3.24 0.25B,bcd4.95 0.14A,b3.42 0.30B,c2.84 0.34B,de4.50 0.45A,c2.78 0.36B,d3.16 0.31B,cd4.44 0.38A,c2.78 0.33B,d2.90 0.32B,de4.18 0.18A,c2.40 0.27B,d3.32 0.43bcd4.58 0.59c3.42 0.34c1.98 0.29B,e3.28 0.4A,d)0.30 0.30C,e3.46 0.27A,bcd4.00 0.56A,c)0.02 0.30B,e3.14 0.50A,cd2.14 0.44A,d)1.58 0.35B,f4.28 0.32A,b2.05 0.85B,d)1.95 0.85C,fp < 0:001p < 0:001p < 0:001P2 p < 0:05 p < 0:01 p < 0:05 p < 0:05 p < 0:01 p < 0:001 p < 0:001 p < 0:001 p < 0:001P1, significant differences within group compared to baseline value (a,b,c,d,e,f), (p < 0:001); P2, in each column different letters (A, B, C) indicated significant between groups (p < 0:01, p < 0:05,p < 0:001); BEact, extracelluler base excess (mmol/l); BEstd, blood base excess (mmol/l).

G. Gokce et al. / Research in Veterinary Science 76 (2004) 121–127 125Blood acid–base <strong>and</strong> blood gas values are summarisedin Tables 1–4 <strong>and</strong> Fig. 1. The pH values <strong>of</strong> the sampleskept at different <strong>temperature</strong>s tended to decrease significantlywith <strong>time</strong> in all groups (p < 0:001) (Fig. 1).Compared to initial values, pH values were found todecrease significantly after 5, 3 <strong>and</strong> 2 h (p < 0:001) for thesamples stored at +4, 22 <strong>and</strong> 37 °C, respectively.Alterations in pCO 2 <strong>and</strong> pO 2 values are summarisedin Table 1. The mean pCO 2 values <strong>of</strong> the samples storedat +4 °C decreased significantly between 1 <strong>and</strong> 24 h, butlater increased again to their initial levels. Moreover, thepCO 2 values <strong>of</strong> the samples kept at 22 <strong>and</strong> 37 °C increasedsignificantly (p < 0:001) after the fourth hour<strong>and</strong> continued to increase until the end <strong>of</strong> the study(Table 1). The maximum mean alteration in pCO 2 valuefor Group I was )0.72 kPa during the assessment, whilefor groups II <strong>and</strong> III maximum alterations for pCO 2were detected as +2.68 <strong>and</strong> +4.16 kPa, respectively. ThepO 2 values <strong>of</strong> the samples kept at +4 <strong>and</strong> 22 °C increasedwith <strong>time</strong> (p < 0:001). However, a significantdecrease was recorded after 24 h for the samples kept at37 °C(p < 0:001). Values <strong>of</strong> O 2 SAT in group I increased(p < 0:05) after 24 h <strong>storage</strong>, on the other h<strong>and</strong> it wassignificantly decreased in group III after 5 h (p < 0:001)<strong>and</strong> there were no changes in group II (p > 0:333) (Table2). The O 2 CT values were significantly increased(p < 0:05) after 24 h <strong>of</strong> <strong>storage</strong> at +4 °C, but significantlydecreased after 4 h <strong>of</strong> <strong>storage</strong> at 37 °C(p < 0:001)(Table 2). However, no significant alterations were observedin the O 2 CT values <strong>of</strong> the samples stored at22 °C. BE <strong>and</strong> HCO 3 concentrations decreased significantlyfor all three groups during the study compared totheir baseline values. The most prominent decrease inBE <strong>and</strong> HCO 3 concentrations was recorded for thesamples kept at 37 °C (Tables 3 <strong>and</strong> 4).4. DiscussionThe effects <strong>of</strong> <strong>storage</strong> <strong>time</strong> <strong>and</strong> <strong>temperature</strong> on bloodgases <strong>and</strong> acid–base values in humans (Mahoney et al.,1991; Liss <strong>and</strong> Payne, 1993; Beaulieu et al., 1999; Lenfant<strong>and</strong> Aucutt, 1965) <strong>and</strong> in cattle (Poulsen <strong>and</strong>Surynek, 1977; Szenci <strong>and</strong> Besser, 1990; Szenci et al.,1991) have been investigated intensively. Previousstudies have revealed that the blood gas <strong>and</strong> acid–basevalues <strong>of</strong> human blood samples usually stabilised between15 min <strong>and</strong> 2 h (Paerregaard et al., 1987; Mahoneyet al., 1991; Beaulieu et al., 1999). The effect <strong>of</strong><strong>storage</strong> <strong>temperature</strong> <strong>and</strong> <strong>storage</strong> <strong>time</strong> on blood gas <strong>and</strong>acid–base values in cattle are disputed (Poulsen <strong>and</strong>Surynek, 1977; Szenci <strong>and</strong> Besser, 1990; Szenci et al.,1991). Szenci <strong>and</strong> Besser (1990) reported that cattle venousblood acid–base values could be used for diagnosticpurposes up to 24 h. On the other h<strong>and</strong>, the pHvalues <strong>of</strong> blood samples taken from cattle <strong>and</strong> stored at+4 °C stabilised after for 5–6 h (Poulsen <strong>and</strong> Surynek,1977). In the present study, the pH values <strong>of</strong> the bloodsamples stored at +4 °C were found to be suitable forclinical usage up to 48 h (Fig. 1). Furthermore, <strong>storage</strong><strong>time</strong> <strong>and</strong> <strong>temperature</strong> were found to significantly alterthe blood pH <strong>and</strong> bicarbonate values <strong>of</strong> all groups.7,45pH7,47,357,37,257,27,15aaaaababababcbcGroup IGroup IIGroup IIIA,abA,bcB,cd**A,abcB,cdC,de***A,bcB,cdeC,e***A,bcB,deC,f***A,bcdB,eC,g***A,bcdB,fC,hA.cdB,gC,hA,dB,gC,h*********7,1*********7,050 1 2 3 4 5 6 12 24 36 48Fig. 1. <strong>Effect</strong>s <strong>of</strong> <strong>storage</strong> <strong>time</strong> on the pH <strong>of</strong> bovine venous blood samples stored at +4 °C (Group I), 22 °C (Group II) <strong>and</strong> 37 °C (group III) (n ¼ 5)(mean SE). a,b,c,d,e,f,g,h: significant differences within group compared to baseline (0 h), ***(p < 0:001). A,B,C: significant differences betweengroup **(p < 0:01), ***(p < 0:001).

126 G. Gokce et al. / Research in Veterinary Science 76 (2004) 121–127Particularly, rapid <strong>and</strong> significant decreases in blood pH(p < 0:001) were observed for those samples stored at37 °C, compared to the other groups (Groups I <strong>and</strong> II)(Fig. 1). Metabolism <strong>of</strong> in vitro blood samples continuesduring <strong>storage</strong>. Oxygen consumption occurs due to anaerobicmetabolism <strong>and</strong> CO 2 generation in the tricarboxylicacid cycles (TCA). Additionally, lactic acid isaccumulated via glycolysis depending on anaerobicmetabolism. These metabolic activities cause a decreasein blood pH (Andersen, 1961; Szenci <strong>and</strong> Besser, 1990;Boink et al., 1991; Liss <strong>and</strong> Payne, 1993). Since samplingerror was reduced to a minimal level in the present studythe decrease in blood pH <strong>and</strong> HCO 3 was attributed tothe formation <strong>of</strong> lactic acid due to glycolysis <strong>and</strong> to anincrease in the level <strong>of</strong> pCO 2 . Moreover, the muchgreater decrease in the pH <strong>of</strong> the blood samples stored at37 °C may be attributed to lactic acid generation due torapid anaerobic metabolism as a result <strong>of</strong> the high<strong>storage</strong> <strong>temperature</strong> (Liss <strong>and</strong> Payne, 1993).In the present study, increases in the pCO 2 values <strong>of</strong>the blood samples kept at 37 °C <strong>and</strong> at room <strong>temperature</strong><strong>and</strong> a decrease in those <strong>of</strong> the samples stored at+4 °C were recorded as compared to their baselinevalues. Researchers have reported that in vitro bloodpCO 2 value rises depending on aerobic <strong>and</strong> anaerobicmetabolism in blood cells (S<strong>and</strong>hagen et al., 1988;Szenci <strong>and</strong> Besser, 1990; Beaulieu et al., 1999). UnlikeO 2 ,CO 2 does not influx through plastic syringe walls(Mahoney et al., 1991), <strong>and</strong> therefore the significantrises <strong>of</strong> pCO 2 in groups II <strong>and</strong> III may be the result <strong>of</strong>high cell metabolic activities at +22 <strong>and</strong> 37 °C (Foster<strong>and</strong> Terry, 1967). Moreover the most prominent increasein pCO 2 was observed in the sample stored at37 °C. The significant decrease in the pCO 2 values <strong>of</strong>the samples stored at +4 °C may be due to the bloodbeing transferred to a lower than body <strong>temperature</strong>medium (Mahoney et al., 1991).In the case <strong>of</strong> blood samples stored over <strong>time</strong>, thetype <strong>of</strong> syringe used for sampling (Mahoney et al., 1991;Beaulieu et al., 1999) <strong>and</strong> the aerobic metabolism <strong>of</strong>leucocytes (Poulsen <strong>and</strong> Surynek, 1977; Haskins, 1977)in the blood have been determined to influence alterationsin the levels <strong>of</strong> pO 2 . It has been revealed that pO 2in plastic syringes increases by the diffusion <strong>of</strong> oxygenthrough the plastic wall <strong>of</strong> the syringe (Paerregaard etal., 1987; Beaulieu et al., 1999). Leucocytes are responsiblefor most <strong>of</strong> the aerobic metabolism in the blood(Liss <strong>and</strong> Payne, 1993) <strong>and</strong> cause O 2 consumption inblood samples stored under in vitro anaerobic conditions(S<strong>and</strong>hagen et al., 1988; Szenci <strong>and</strong> Besser, 1990).A decrease in pO 2 values has been found in bloodsamples with high leucocyte counts (Schimidt <strong>and</strong>Plathe, 1992) <strong>and</strong> in samples with anaemia (Haskins,1977). Since the initial mean leucocyte <strong>and</strong> erythrocytenumbers <strong>and</strong> haemoglobin concentrations <strong>of</strong> the bloodsamples were within normal range in the present study,the significant decrease (p < 0:001) in pO 2 level found inthe blood samples stored at 37 °C after 24 h may beattributed to an increase in aerobic metabolism <strong>and</strong> O 2consumption by leucocytes due to the high <strong>storage</strong><strong>temperature</strong> (Liss <strong>and</strong> Payne, 1993). A significant increasein the level <strong>of</strong> pO 2 was detected after 6 h in thesamples stored at room <strong>temperature</strong> <strong>and</strong> in the refrigeratedsamples. This may have been due to the release <strong>of</strong>O 2 from haemoglobin as a result <strong>of</strong> the reduction inblood pH (Szenci <strong>and</strong> Besser, 1990) <strong>and</strong> to the diffusion<strong>of</strong> O 2 through the plastic syringe wall (Beaulieu et al.,1999; Mahoney et al., 1991) although oxygen consumptionoccurs during aerobic cell metabolism.Moreover, this finding reflects the fact that aerobicmetabolism <strong>of</strong> leucocyte was lower at room <strong>temperature</strong><strong>and</strong> under +4 °C in vitro conditions than at 37 °C.The SAT O 2 value also decreased together with pH inthe blood samples kept at 37 °C. This can be explainedby the shifting <strong>of</strong> the haemoglobin–O 2 dissociationcurve to the right (Bohr effect) due to decrease in bloodpH (Szenci <strong>and</strong> Besser, 1990; Carlson, 1996). The O 2 CT<strong>and</strong> O 2 SAT value displayed the least alteration withinthe parameters for the blood samples kept at room<strong>temperature</strong> <strong>and</strong> at +4 °C, which is consisted the findings<strong>of</strong> Beaulieu et al. (1999) in a study carried out onhuman blood. Therefore, we suggest that the O 2 CT <strong>and</strong>O 2 SAT value should be taken into consideration forblood samples stored at room <strong>temperature</strong> when assessingblood O 2 .In conclusion, the acid–base values <strong>of</strong> the samplesstored at 22 <strong>and</strong> 37 °C changed significantly whencompared to the samples stored at +4 °C. However, theacid–base values <strong>of</strong> the samples stored at 22 <strong>and</strong> +4 °Cwere within normal range <strong>and</strong> could be used for clinicalpurposes for up to 12 <strong>and</strong> 48 h, respectively.ReferencesAndersen, O.S., 1961. 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