Premature Infants Are Less Capable of Maintaining Thermal Balance of Head and Body with Increases of Thermal Environment than with Decreases

Simbruner, G.; Ruttner, Eva-Maria; Schulze, Andreas; Perzlmaier, Katharina

doi:10.1055/s-2004-837265

Cited by 15 publications

(10 citation statements)

References 21 publications

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“…Intraischemia cooling contributed to profound protection in the cortex, and this protection was correlated with down‐regulation of apoptosis‐related mechanisms and up‐regulation of the Akt survival signalling pathway. The prevailing routine in clinical practice to prioritize warming neonates in the resuscitation situation may be harmful to the brain (Simbruner et al ., 2005).…”

Section: Discussionmentioning

confidence: 99%

Intraischemic mild hypothermia prevents neuronal cell death and tissue loss after neonatal cerebral hypoxia–ischemia

Zhu¹,

Wang²,

Xu³

et al. 2006

Eur J of Neuroscience

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The effectiveness of hypothermia in preventing ischemic brain damage depends on when it is started. The purpose of this study was to investigate the effects of temperature reduction during a hypoxic-ischemic (HI) insult on brain injury and signalling pathways of neuronal cell death and survival. Seven-day-old mice were subjected to left common carotid artery ligation and hypoxia (10% oxygen) at different temperatures (37, 36 or 34 degrees C) for 50 min. Brain injury at 7 days post-HI was significantly reduced from 67.4% at 37 degrees C to 31.6% at 36 degrees C and 10% at 34 degrees C, with no observable injury in the cortex of the 34 degrees C group. Cytochrome c release, caspase-3 activation and apoptosis-inducing factor translocation from mitochondria to nuclei were all significantly inhibited after intraischemic temperature reduction. Concurrently, the cell survival signalling pathway involving Akt was significantly sustained (the phosphorylated form of Akt was maintained) when the hypoxia temperature was decreased. These results indicate that intraischemic hypothermia diminished apoptosis through inhibition of both caspase-dependent and caspase-independent neuronal cell death pathways and promoted cell survival by inhibition of phosphorylated Akt dephosphorylation in the neonatal brain, thereby preventing neuronal cell death.

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Section: Discussionmentioning

confidence: 99%

Intraischemic mild hypothermia prevents neuronal cell death and tissue loss after neonatal cerebral hypoxia–ischemia

Zhu¹,

Wang²,

Xu³

et al. 2006

Eur J of Neuroscience

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“…Zero-heat-flux core temperature monitoring using a temperature probe covered by a piece of heat insulator is widely accepted as a reliable surrogate marker for invasive methods (Simbruner et al, 2005(Simbruner et al, , 1994van der Spek et al, 2009). Fox and Solman (1971) further improved this technique using a heater and a thermal flux transducer, the accuracy of which has been validated in a range of body locations and clinical situations in reference to jugular vein and other body core temperatures (Yamakage and Namiki, 2003;Kimberger et al, 2009;Akata et al, 2007;Ball et al, 1973).…”

Section: Non-invasive Monitoring Of Brain Temperaturementioning

confidence: 99%

“…Local heat production is represented by cerebral metabolism, whereas heat removal depends on cerebral blood flow (CBF) and heat dissipation through the scalp (Sukstanskii and Yablonskiy, 2006). Previous pre‐clinical and clinical studies have identified factors that determine body/brain temperature in newborn infants, such as ambient temperature and humidity, and maturity and body size (Karlsson et al, 1995; Simbruner et al, 2005; Iwata et al, 2006). However, associations between brain temperature, metabolism, and perfusion have not been fully investigated.…”

Section: Introductionmentioning

confidence: 99%

Dual role of cerebral blood flow in regional brain temperature control in the healthy newborn infant

Iwata

Tachtsidis

Takashima

et al. 2014

Intl J of Devlp Neuroscience

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Small shifts in brain temperature after hypoxia-ischaemia affect cell viability. The main determinants of brain temperature are cerebral metabolism, which contributes to local heat production, and brain perfusion, which removes heat. However, few studies have addressed the effect of cerebral metabolism and perfusion on regional brain temperature in human neonates because of the lack of non-invasive cot-side monitors. This study aimed (i) to determine non-invasive monitoring tools of cerebral metabolism and perfusion by combining near-infrared spectroscopy and echocardiography, and (ii) to investigate the dependence of brain temperature on cerebral metabolism and perfusion in unsedated newborn infants. Thirty-two healthy newborn infants were recruited. They were studied with cerebral near-infrared spectroscopy, echocardiography, and a zero-heat flux tissue thermometer. A surrogate of cerebral blood flow (CBF) was measured using superior vena cava flow adjusted for cerebral volume (rSVC flow). The tissue oxygenation index, fractional oxygen extraction (FOE), and the cerebral metabolic rate of oxygen relative to rSVC flow (CMRO₂ index) were also estimated. A greater rSVC flow was positively associated with higher brain temperatures, particularly for superficial structures. The CMRO₂ index and rSVC flow were positively coupled. However, brain temperature was independent of FOE and the CMRO₂ index. A cooler ambient temperature was associated with a greater temperature gradient between the scalp surface and the body core. Cerebral oxygen metabolism and perfusion were monitored in newborn infants without using tracers. In these healthy newborn infants, cerebral perfusion and ambient temperature were significant independent variables of brain temperature. CBF has primarily been associated with heat removal from the brain. However, our results suggest that CBF is likely to deliver heat specifically to the superficial brain. Further studies are required to assess the effect of cerebral metabolism and perfusion on regional brain temperature in low-cardiac output conditions, fever, and with therapeutic hypothermia.

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“…23 With this on-off control, there is an overshoot and undershoot in the air temperature. 2,16,18,[21][22][23][24] Skin control often leads to large fluctuations in air temperature. 5,6,18 Air control leads to skin temperature fluctuations.…”

Section: Introductionmentioning

confidence: 99%

“…2,16,18,[21][22][23][24] Skin control often leads to large fluctuations in air temperature. 5,6,18 Air control leads to skin temperature fluctuations. Perlstein et al 17 observed that apnea in newborns was caused by thermal instability.…”

Section: Introductionmentioning

confidence: 99%

Toward a Fuzzy Logic Control of the Infant Incubator

2009

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Premature birth is a world wide problem. Thermo regulation is a major problem in premature infants. Premature infants are often kept in infant incubators providing convective heating. Currently either the incubator air temperature is sensed and used to control the heat flow, or infant's skin temperature is sensed and used in the close loop control. Skin control often leads to large fluctuations in the incubator air temperature. Air control also leads to skin temperature fluctuations. The question remains if both the infant's skin temperature and the incubator air temperature can be simultaneously used in the control. The purpose of the present study was to address this question by developing a fuzzy logic control which incorporates both incubator air temperature and infant's skin temperature to control the heating. The control was evaluated using a lumped parameter mathematical model of infant-incubator system (Simon, B. N., N. P. Reddy, and A. Kantak, J. Biomech. Eng. 116:263-266, 1994). Simulation results confirmed previous experimental results that the on-off skin control could lead to fluctuations in the incubator air temperature, and the air control could lead to too slow rise time in the core temperature. The fuzzy logic provides a smooth control with the desired rise time.

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Premature Infants Are Less Capable of Maintaining Thermal Balance of Head and Body with Increases of Thermal Environment than with Decreases

Cited by 15 publications

References 21 publications

Intraischemic mild hypothermia prevents neuronal cell death and tissue loss after neonatal cerebral hypoxia–ischemia

Intraischemic mild hypothermia prevents neuronal cell death and tissue loss after neonatal cerebral hypoxia–ischemia

Dual role of cerebral blood flow in regional brain temperature control in the healthy newborn infant

Toward a Fuzzy Logic Control of the Infant Incubator

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