1653 and Isoflurane Produce Similar Dose-related Changes in the Electroencephalogram of Pigs

Rampil, Ira J.; Welskopf, Richard B.; Brown, Joanna G.; Eger, Edmond I.; Johnson, Brynte H.; Holmes, Margot A.; Donegan, Judith H.

doi:10.1097/00000542-198809000-00002

Cited by 113 publications

(63 citation statements)

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“…Interestingly, this depression has been observed despite a restitution of high-energy metabolites in awake rats that showed exploratory behavior and recovery of motor functions (23). Potential causes of the postischemic cerebral depression observed in this study include the prolonged effect of a release of adenosine, which occurs during hypoxia and ischemia and acts by inhibiting synaptic activity (24); mitochondrial dysfunction, caused by either ischemic damage or inhibition by the postischemic release of nitric oxide (25); or perhaps an increased sensitivity to the anesthetic agent, isoflurane, which could have caused an increase in mean alveolar concentration and possibly a reduction in synaptic activity that would have reduced metabolic demand (26).…”

Section: Discussionmentioning

confidence: 89%

Assessing the Severity of Perinatal Hypoxia-Ischemia in Piglets Using Near-Infrared Spectroscopy to Measure the Cerebral Metabolic Rate of Oxygen

et al. 2009

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Reduced cerebral function after neonatal hypoxiaischemia is an early indicator of hypoxic-ischemic encephalopathy. Near-infrared spectroscopy offers a clinically relevant means of detecting impaired cerebral metabolism from the measurement of the cerebral metabolic rate of oxygen (CMRO 2 ). The purpose of this study was to determine the relationship between postinsult CMRO 2 and duration of hypoxia-ischemia in piglets. Twelve piglets were subjected to randomly selected durations of hypoxia-ischemia (5-28 min) and five animals served as controls. Measurements of CMRO 2 were taken before and for 24 h after hypoxia-ischemia. Histology was carried out in nine piglets (six insults, three controls) to estimate brain injury. In the first 4 h after the insult, average CMRO 2 of the insult group was significantly depressed (33 Ϯ 3% reduction compared with controls) and by 8 h, a significant correlation developed, which persisted for the remainder of the study, between CMRO 2 and the duration of ischemia. Histologic staining suggested little brain damage resulted from shorter insult durations and considerable damage from more prolonged insults. This study demonstrated that near-infrared spectroscopy could detect early changes in CMRO 2 after hypoxia-ischemia for a range of insult severities and CMRO 2 could be used to distinguish insult severity by 8 h after the insult. (Pediatr Res 65: 301-306, 2009) P erinatal hypoxia-ischemia continues to be a significant cause of neurodevelopmental impairment and disability in the term infant. Results from animal and newborn human studies suggest a significant portion of hypoxic-ischemic brain damage can be delayed by 6 -72 h after resuscitation (1). Long-term outcome could be improved if mechanisms leading to delayed cell death could be suppressed during the latent period between insult and injury-a period termed the "therapeutic window" (2). The exact duration of the therapeutic window is unknown; however, the success rate of treatment strategies depends on early administration. Unfortunately, the clinical signs of perinatal hypoxia-ischemia can be subtle and there are as yet no proven methods capable of reliably and accurately assessing the severity of injury within the confines of the therapeutic window (2).For nearly 30 y it has been known that cerebral ischemia can cause long-term depression of cerebral metabolism despite resuscitation (3). Studies conducted in neonatal lambs demonstrated that a reduction in cerebral energy metabolism can be seen within 4 h after resuscitation from hypoxiaischemia (4,5) and metabolic impairment has been similarly observed in newborns within 18 h of birth by proton magnetic resonance spectroscopy (6), while delayed energy failure, as quantified by phosphorous magnetic resonance spectroscopy, can be used to predict neurologic outcome (7). The results of these studies suggest that a noninvasive measure of the cerebral metabolic rate of oxygen (CMRO 2 ) may be of particular interest to the clinical prognosis of hypoxia-ischemia.Recent tech...

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Section: Discussionmentioning

confidence: 89%

Assessing the Severity of Perinatal Hypoxia-Ischemia in Piglets Using Near-Infrared Spectroscopy to Measure the Cerebral Metabolic Rate of Oxygen

et al. 2009

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“…In our laboratory's previous study, piglets were kept anesthetized by isoflurane at all times. Isoflurane is known to depress metabolism, and its effects may have been magnified during early reperfusion, if prolonged hypoxia affected the clearance rate of the agent (29).…”

Section: Discussionmentioning

confidence: 99%

Cerebral metabolic rate of oxygen and amplitude-integrated electroencephalography during early reperfusion after hypoxia-ischemia in piglets

Tichauer¹,

Elliott²,

Hadway³

et al. 2009

Journal of Applied Physiology

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Tichauer KM, Elliott JT, Hadway JA, Lee T, St. Lawrence KS. Cerebral metabolic rate of oxygen and amplitude-integrated electroencephalography during early reperfusion after hypoxia-ischemia in piglets. J Appl Physiol 106: 1506 -1512. First published March 19, 2009 doi:10.1152/japplphysiol.91156.2008.-The therapeutic window following perinatal hypoxia-ischemia is brief, and early clinical signs of injury can be subtle. Electroencephalography (EEG) represents the most promising early diagnostic of hypoxia-ischemia; however, some studies have questioned the sensitivity and specificity of EEG. The present study investigated the use of both near-infrared spectroscopy (NIRS) measurements of the cerebral metabolic rate of oxygen (CMRO 2) and amplitude-integrated EEG (aEEG) to detect the severity of hypoxia-ischemia after 1 h of reperfusion in newborn piglets (10 insult, 3 control). The CMRO2 was measured before and after 1 h of reperfusion from hypoxia-ischemia, the duration of which was varied from piglet to piglet with a range of 3-24 min, under fentanyl/nitrous oxide anesthesia to mimic awake-like levels of cerebral metabolism. EEG data were collected throughout the study. On average, the CMRO2 and mean aEEG background signals were significantly depressed following the insult (P Ͻ 0.05). Mean CMRO 2 and mean aEEG background were 2.61 Ϯ 0.11 ml O2 ⅐ min Ϫ1 ⅐ 100 g Ϫ1 and 20.4 Ϯ 2.7 V before the insult and 1.58 Ϯ 0.09 ml O2⅐min Ϫ1 ⅐100 g Ϫ1 and 11.8 Ϯ 2.9 V after 1 h of reperfusion, respectively. Both CMRO2 and aEEG displayed statistically significant correlations with duration of ischemia (P Ͻ 0.05; r ϭ 0.71 and r ϭ 0.89, respectively); however, only CMRO2 was sensitive to milder injuries (Ͻ5 min). This study highlights the potential for combining NIRS measures of CMRO2 with EEG in the neonatal intensive care unit to improve early detection of perinatal hypoxia-ischemia. near-infrared spectroscopy; piglet; hypoxia-ischemia; electroencephalography PERINATAL HYPOXIC-ISCHEMIC encephalopathy is a substantial cause of infant mortality and morbidity. It remains a detrimental factor in roughly 1 of every 500 live term births in developed nations, leading to long-term neurological and developmental disabilities (20). Recent clinical trials have demonstrated that the incidence of death and disability from hypoxia-ischemia in newborns can be significantly reduced by initiating treatment strategies, hypothermia, for example, after birth and within a 6-h therapeutic window (9,11,14,32). Due to the brevity of the therapeutic window, early detection of injury and early determination of those infants who are likely candidates for treatment are crucial (15). In this regard, traditional early indicators of brain injury, including Apgar scores, umbilical artery acidosis, and fetal heart rate monitoring, suffer from poor specificity (7, 31), and more specific indicators of injury, such as magnetic resonance imaging and spectroscopy, are insensitive or difficult to implement within the therapeutic window (6, 21).To this point, the most...

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“…Background activity was automatically measured by computing the "burst suppression ratio" (BSR) 18 and the approximate entropy 19 on Fz, Cz and Pz. In the BSR, suppression intervals are defined as periods longer than 240 ms during which EEG voltage does not exceed 5μV 18 . BSR represents the ratio between the total suppression time and the total recording time.…”

Section: Automatic Analysismentioning

confidence: 99%

“…We also investigated their prognostic value. Background EEG was analyzed with two methods developed to monitor anesthesia: the burst suppression ratio (BSR) 18 and the approximate entropy 19,20 . Reactivity was analyzed with a method based on frequency features of the signal.…”

Section: Introductionmentioning

confidence: 99%

Automated Analysis of Background EEG and Reactivity During Therapeutic Hypothermia in Comatose Patients After Cardiac Arrest

et al. 2014

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Visual analysis of EEG background and reactivity during therapeutic hypothermia provides important outcome information, but is time-consuming and not always consistent between reviewers. An automated EEG analysis approach may help to quantify the brain damage. Fortysix comatose patients in therapeutic hypothermia after cardiac arrest were included in the study. EEG background was quantified with burst-suppression ratio and approximate entropy, both used to monitor anesthesia. Reactivity was detected through change in the power spectrum of signal before and after stimulation. Automatic results obtained almost perfect agreement (discontinuity) to substantial agreement (background reactivity) with a visual score from EEGcertified neurologists. Burst-suppression ratio was more suited to distinguish continuous EEG background from burst-suppression than approximate entropy in this specific population. Automatic EEG background and reactivity measures were significantly related to good and poor outcome. We conclude that quantitative EEG measurements can provide promising information regarding current state of the patient and clinical outcome, but further work is needed before a routine application in a clinical setting.

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1653 and Isoflurane Produce Similar Dose-related Changes in the Electroencephalogram of Pigs

Cited by 113 publications

References 0 publications

Assessing the Severity of Perinatal Hypoxia-Ischemia in Piglets Using Near-Infrared Spectroscopy to Measure the Cerebral Metabolic Rate of Oxygen

Assessing the Severity of Perinatal Hypoxia-Ischemia in Piglets Using Near-Infrared Spectroscopy to Measure the Cerebral Metabolic Rate of Oxygen

Cerebral metabolic rate of oxygen and amplitude-integrated electroencephalography during early reperfusion after hypoxia-ischemia in piglets

Automated Analysis of Background EEG and Reactivity During Therapeutic Hypothermia in Comatose Patients After Cardiac Arrest

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