pH-Stat Versus α-Stat Acid–Base Management Strategy During Hypothermic Circulatory Arrest Combined With Embolic Brain Injury

Dahlbacka, Sebastian; Heikkinen, Jouni; Kaakinen, Timo; Laurila, Päivi; Vainionpää, Vilho; Kiviluoma, Kai; Salomäki, Timo; Tuominen, Hannu; Ohtonen, Pasi; Biancari, Fausto; Lepola, Pasi; Juvonen, Tatu

doi:10.1016/j.athoracsur.2004.09.022

Cited by 18 publications

(8 citation statements)

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“…In contrast, several studies in pig and piglet models of deep hypothermic arrest found improved cerebral physiologic recovery with pH-stat management. [16][17][18][19][20] It is not clear if the outcome of these studies performed in hypothermic pigs in circulatory arrest can be translated to the clinical condition of mild hypothermia in asphyxiated term neonates. Li et al 26 suggested that in mild hypothermia, brain tissue oxygen saturation in ␣-stat management was greater than that in pH-stat management.…”

Section: Studies Comparing the ␣-Stat And Ph-stat Methodsmentioning

confidence: 99%

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Blood Gas Values During Hypothermia in Asphyxiated Term Neonates

2009

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The authors have indicated they have no financial relationships relevant to this article to disclose.H YPOTHERMIA HAS BECOME an important novel neuroprotective strategy for asphyxiated term neonates. 1 Most of these neonates will receive mechanical ventilation. Hypothermia affects blood gas parameters such as pH and PCO 2 . At lower temperatures pH increases and PCO 2 decreases. This is relevant, because PaCO 2 is known to affect vascular tone and, hence, cerebral perfusion. 2 In addition, cerebral blood flow decreases during hypothermia, which increases the risk of insufficient blood flow during hypocapnia. 3 Most blood gas instruments, whether a central laboratory or point-of-care device, contain a temperaturecontrolled sample chamber specified to be 37°C. It is at that temperature that all measurements of pH and partial pressure of gases are performed. In the ␣-stat strategy, uncorrected values are used to keep the pH and PCO 2 close to the 37°C reference value. 4 However, most instruments can calculate and present temperature-corrected pH and PCO 2 values. In the so-called pH-stat method, the measured pH is corrected to the actual body temperature of the patient. Ventilator settings can be adjusted to keep the actual pH as close to 7.4 as possible. 4 At present, it is unclear whether the ␣-stat or pH-stat theory should be used in the neuroprotective strategy for asphyxiated term neonates.In the 2 large randomized, controlled trials on therapeutic hypothermia in term neonates with perinatal asphyxia, attending physicians were advised to correct blood gases and pH for rectal temperature. 5,6 Here we will summarize the relevance of blood gas values in and the effects on cellular function during hypothermia. HYPOTHERMIA, PCO 2 , AND pHPhysical laws determine that the solubility of a gas within a liquid decreases when lowering the temperature. During hypothermia, arterial PCO 2 decreases and pH increases compared with 37°C when measurements are made at the actual body temperature (Fig 1). In healthy subjects with a body temperature of 37°C, pH and PaCO 2 should approach 7.4 and 5.3 kPa (40 mm Hg), respectively. During hypothermia (33°C), pH will rise to 7.5 and PCO 2 will decrease to 4.5 kPa (34 mm Hg). PaCO 2 AND CEREBRAL BLOOD FLOWUnder normal conditions, term neonates autoregulate their cerebral blood flow in response to changes in systemic arterial pressure, but this mechanism can be impaired during neonatal distress. 7 In particular, changes in PaCO 2 have a well-recognized effect on cerebral blood flow. Hypocapnia induces cerebral vasoconstriction and may decrease cerebral tissue high-energy phosphates. 8,9 This effect has been extensively investigated in experiments in neonatal animals. [9][10][11] In preterm neonates, profound hypocapnia below values of 4 kPa (30 mm Hg) was related to periventricular leukomalacia. 12 There is little reason to assume that hypocapnia could not damage the brain in the sick term neonate. 13 Klinger et al 14 reported that in asphyxiated term neonates early hypocapnia was indepe...

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Section: Studies Comparing the ␣-Stat And Ph-stat Methodsmentioning

confidence: 99%

“…E-mail: f.groenendaal@umcutrecht.nl PEDIATRICS (ISSN Numbers: Print, 0031-4005; Online, 1098-4275). Copyright © 2009 by the American Academy of Pediatrics latory arrest in pigs have shown that pH-stat management could confer neurologic protection against ischemia [16][17][18][19][20]. …”

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Blood Gas Values During Hypothermia in Asphyxiated Term Neonates

2009

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“…Monitoring of anesthesia, preoperative management, and electrocardiographic, hemodynamic, intracerebral, and systemic metabolic parameters as well as evaluation of behavioral outcome and histopathological analysis were performed as described in detail in our previous study employing the same experimental model of HCA alone or combined with cerebral embolization [Romsi 2003;Dahlbacka 2005].…”

Section: Anesthesia and Monitoringmentioning

confidence: 99%

“…Low pH of the drug led to increased levels of CO 2 . Although high Paco 2 dilates cerebral vessels [Duebener 2002] and itself has protective properties to the brain [Dahlbacka 2005], the difference between groups is hardly significant from a clinical point of view and the effect was short-lasting. The lower levels of sodium and osmolarity observed in the FDP group most likely are due to better fluid balance.…”

Section: E832mentioning

confidence: 99%

Fructose- 1,6-Bisphosphate Supports Cerebral Energy Metabolism in Pigs after Ischemic Brain Injury Caused by Experimental Particle Embolization

Kaakinen¹,

Heikkinen²,

Dahlbacka³

et al. 2006

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The administration of FDP before and immediately after HCA combined with embolic brain ischemic injury was associated with significantly lower brain lactate/pyruvate ratio and significantly higher levels of brain pyruvate, as well as lower lactate levels 8 hours after HCA. FDP seems to protect the brain by supporting energy metabolism. The neurological outcome was not improved, most likely resulting from the irreversible nature of the microsphere occlusion.

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“…76 Empirically, in an animal (pig) model of controlled microembolic load during DHCA, pH-stat was associated with improved outcomes when compared with alpha-stat. 77 In the absence of definitive data favoring one strategy over the other, it might be prudent to use a combined strategy in which pH-stat is used while cooling, thus using the benefits of cerebral vasodilatation to enhance the rate and homogeneity of brain cooling; followed by the alpha-stat strategy from the interval immediately before cessation of circulation to the time of rewarming, thus minimizing extracellular acidosis and aiming for the preservation of CBF-CMRO 2 coupling during reperfusion and rewarming. 78…”

Section: Acid-base Management During Hypothermiamentioning

confidence: 99%