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Davidson JO, van den Heuij LG, Dhillon SK, Miller SL, Lim R, Jenkin G, Gunn AJ, Bennet L. Lack of Neuroprotection with a Single Intravenous Infusion of Human Amnion Epithelial Cells after Severe Hypoxia–Ischemia in Near-Term Fetal Sheep. Int J Mol Sci 2022; 23:ijms23158393. [PMID: 35955531 PMCID: PMC9369428 DOI: 10.3390/ijms23158393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 07/27/2022] [Accepted: 07/27/2022] [Indexed: 12/02/2022] Open
Abstract
Background: Hypoxic–ischemic encephalopathy (HIE) around the time of birth results from loss of oxygen (hypoxia) and blood supply (ischemia). Exogenous infusion of multi-potential cells, including human amnion epithelial cells (hAECs), can reduce hypoxic–ischemic (HI) brain injury. However, there are few data on treatment of severe HI in large animal paradigms at term. The aim of the current study was to determine whether infusion of hAECs early after injury may reduce brain damage after ischemia in near-term fetal sheep. Methods: Chronically instrumented fetal sheep (0.85 gestation) received 30 min of global cerebral ischemia followed by intravenous infusion of hAECs from 2 h after the end of ischemia (ischemia-hAEC, n = 6) or saline (ischemia-vehicle, n = 7). Sham control animals received sham ischemia with vehicle infusion (sham control, n = 8). Results: Ischemia was associated with significant suppression of EEG power and spectral edge frequency until the end of the experiment and a secondary rise in cortical impedance from 24 to 72 h, which were not attenuated by hAEC administration. Ischemia was associated with loss of neurons in the cortex, thalamus, striatum and hippocampus, loss of white matter oligodendrocytes and increased microglial numbers in the white matter, which were not affected by hAEC infusion. Conclusions: A single intravenous administration of hAECs did not reduce electrographic or histological brain damage after 30 min of global cerebral ischemia in near-term fetal sheep.
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Affiliation(s)
- Joanne O. Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland 1010, New Zealand; (L.G.v.d.H.); (S.K.D.); (A.J.G.); (L.B.)
- Correspondence:
| | - Lotte G. van den Heuij
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland 1010, New Zealand; (L.G.v.d.H.); (S.K.D.); (A.J.G.); (L.B.)
| | - Simerdeep K. Dhillon
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland 1010, New Zealand; (L.G.v.d.H.); (S.K.D.); (A.J.G.); (L.B.)
| | - Suzanne L. Miller
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.L.M.); (R.L.); (G.J.)
- Department of Obstetrics and Gynaecology, Monash University, Clayton 3800, Australia
| | - Rebecca Lim
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.L.M.); (R.L.); (G.J.)
- Department of Obstetrics and Gynaecology, Monash University, Clayton 3800, Australia
| | - Graham Jenkin
- The Ritchie Centre, Hudson Institute of Medical Research, Clayton 3168, Australia; (S.L.M.); (R.L.); (G.J.)
- Department of Obstetrics and Gynaecology, Monash University, Clayton 3800, Australia
| | - Alistair J. Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland 1010, New Zealand; (L.G.v.d.H.); (S.K.D.); (A.J.G.); (L.B.)
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland 1010, New Zealand; (L.G.v.d.H.); (S.K.D.); (A.J.G.); (L.B.)
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Recher M, Prevost ALD, Sharma D, De Jonckheere J, Garabedian C, Storme L. Roles of parasympathetic outflow and sympathetic outflow in the cardiovascular response to brief umbilical cord occlusion in fetal sheep. PLoS One 2021; 16:e0254155. [PMID: 34228770 PMCID: PMC8259953 DOI: 10.1371/journal.pone.0254155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 06/21/2021] [Indexed: 01/08/2023] Open
Abstract
Fetal heart rate (FHR) deceleration is the most common change seen during labor. The role of the autonomic nervous system in regulating the fetal cardiovascular response during multiple uterine contractions has been well-established. However, the mechanism underlying the hemodynamic response remains unclear and the specific reflex that mediates the cardiovascular modifications is still controversial. This study aimed to determine the role of the sympathetic and parasympathetic systems on fetal hemodynamics in complete cord occlusion. Chronically instrumented fetal sheep were randomized to receive an intravenous injection of atropine 2.5 mg (n = 8), propranolol 5 mg (n = 7), atropine and propranolol (n = 7), or a control protocol (n = 9), followed by three episodes of 1-minute umbilical cord occlusion repeated every 5 minutes. Cord compression induces a rapid decrease in the FHR and a rapid increase in MAP. The decrease in FHR is caused by an increase in parasympathetic activity, (atropine and atropine-propranolol abolish the FHR response to the occlusion). The change in FHR during occlusion was not modified by propranolol injection, showing no effect of sympathetic tone. The increase in MAP during occlusion was similar in the four protocols. After releasing occlusion, the FHR was still lower than that at baseline due to a sustained parasympathetic tone. Suppression of the parasympathetic output to the cardiovascular system unmasks an increase in the FHR above baseline values. The lower FHR with the propranolol protocol further supports an increase in myocardial β-adrenoceptor stimulation after cord release. The increase in MAP after cord release was similar in the four protocols, except after the early stage of interocclusion period in atropine protocol. Four minutes after cord release, the FHR returned to baseline irrespective of the drugs that were infused, thereby showing recovery of ANS control. Blood gases (pH, PaCO2, PaO2) and plasma lactate concentrations was similar between the four protocols at the end of three applications of UCO. Complete cord compression-induced deceleration is likely due to acute activation of parasympathetic output. β-adrenoceptor activity is involved in the increase in FHR after cord release. Understanding the reflexes involved in FHR deceleration may help us understand the mechanisms underlying fetal autonomic adaptation during cord occlusion.
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Affiliation(s)
- Morgan Recher
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- Department of Pediatric Intensive Care Unit, CHU Lille, Jeanne de Flandre Hospital, Lille, France
| | - Arthur Lauriot Dit Prevost
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- Department of Pediatric Surgery, CHU Lille, Jeanne de Flandre Hospital, Lille, France
| | - Dyuti Sharma
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- Department of Pediatric Surgery, CHU Lille, Jeanne de Flandre Hospital, Lille, France
| | - Julien De Jonckheere
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- CHU Lille, Centre d’Innovation Technologique, Lille, France
| | - Charles Garabedian
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- Department of Obstetrics, CHU Lille, Jeanne de Flandre Hospital, Lille, France
| | - Laurent Storme
- Univ. Lille, ULR 2694 – METRICS: Evaluation des technologies de santé et des pratiques médicales, Lille, France
- Department of Neonatology, CHU Lille, Jeanne de Flandre Hospital, Lille, France
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Wassink G, Davidson JO, Fraser M, Yuill CA, Bennet L, Gunn AJ. Non-additive effects of adjunct erythropoietin therapy with therapeutic hypothermia after global cerebral ischaemia in near-term fetal sheep. J Physiol 2020; 598:999-1015. [PMID: 31912503 DOI: 10.1113/jp279131] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/02/2020] [Indexed: 01/26/2023] Open
Abstract
KEY POINTS Recombinant human erythropoietin (rEpo) is neuroprotective in immature animals, but it is unclear whether the combination of high-dose rEpo therapy with therapeutic hypothermia can further improve outcomes. Hypothermia and rEpo independently improved neuronal survival, with greater improvement with hypothermia, and similarly reduced numbers of caspase-3 positive cells and reactive microglia after 7 days recovery. Hypothermia, but not rEpo, was associated with markedly improved EEG power, whereas both interventions improved recovery of EEG frequency. There was no significant improvement in any outcome after combined rEpo and hypothermia compared with hypothermia alone, and of concern, the combination was associated with increased numbers of cortical caspase-3-positive cells compared with ischaemia-hypothermia. These data suggest that the mechanisms of neuroprotection with hypothermia and rEpo overlap and, thus, high-dose rEpo infusion does not appear to be an effective adjunct therapy for therapeutic hypothermia. ABSTRACT Therapeutic hypothermia for hypoxic-ischaemic encephalopathy (HIE) provides incomplete neuroprotection. Recombinant human erythropoietin (rEpo) is neuroprotective in immature animals, but it is unclear whether adjunct rEpo therapy with therapeutic hypothermia can further improve outcomes. Near-term fetal sheep received sham-ischaemia (n = 9) or global cerebral ischaemia for 30 min (ischaemia-vehicle, n = 8), followed by intravenous infusion of rEpo (ischaemia-Epo, n = 8; 5000 U/kg loading dose, then 833.3 U/kg/h), cerebral hypothermia (ischaemia-hypothermia, n = 8), or rEpo plus hypothermia (ischaemia-Epo-hypothermia, n = 8), from 3 to 72 h post ischaemia. Fetal brains were collected 7 days after cerebral ischaemia. Cerebral ischaemia was associated with severe neuronal loss and microglial induction in the parasagittal cortex and subcortical regions. Hypothermia reduced overall neuronal loss, cortical caspase-3 and reactive microglia in the striatum and cortex, with greater recovery of electroencephalographic (EEG) power and spectral edge (SEF) from 48 h onwards. rEpo independently improved neuronal survival in the parasagittal cortex, hippocampal CA4 and thalamus, and reduced cortical caspase-3 and activated microglia in striatal and cortical areas, with greater SEF from 120 h onwards. However, ischaemia-Epo-hypothermia did not further improve outcomes compared with ischaemia-hypothermia and was associated with increased numbers of cortical caspase-3-positive cells. These findings suggest that although delayed, prolonged treatment with both hypothermia and rEpo are independently neuroprotective, they have overlapping anti-inflammatory and anti-apoptotic mechanisms, such that the delayed, high-dose rEpo infusion for 3 days did not materially augment neuroprotection with therapeutic hypothermia.
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Affiliation(s)
- Guido Wassink
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Mhoyra Fraser
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Caroline A Yuill
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Laura Bennet
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
| | - Alistair J Gunn
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, New Zealand
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Delhaas T, Andriessen P, van Laar JOEH, Vullings R, Hermans BJM, Niemarkt HJ, Jellema RK, Ophelders DRMG, Wolfs TGAM, Kramer BW, Zwanenburg A. Why -aVF can be used in STAN as a proxy for scalp electrode-derived signal; reply to comments by Kjellmer et al. PLoS One 2019; 14:e0221220. [PMID: 31437178 PMCID: PMC6705853 DOI: 10.1371/journal.pone.0221220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 07/31/2019] [Indexed: 11/18/2022] Open
Abstract
The conclusion of our recent paper that performance of the STAN device in clinical practice is potentially limited by high false-negative and high false-positive STAN-event rates and loss of ST waveform assessment capacity during severe hypoxemia, evoked comments by Kjellmer, Lindecrantz and Rosén. These comments can be summarized as follows: 1) STAN analysis is based on a unipolar lead but the authors used a negative aVF lead, and they did not validate this methodology; 2) The fetuses used in the study were too young to display the signals that the authors were trying to detect. In response to these comments we now provide both a theoretical and an experimental underpinning of our approach. In an in vivo experiment in human we placed several electrodes over the head (simulating different places of a scalp electrode), simultaneously recorded Einthoven lead I and II, and constructed -aVF from these two frontal leads. Irrespective of scalp electrode placement, the correlation between any of unipolar scalp electrode-derived signals and constructed-aVF was excellent (≥ 0.92). In response to the second comment we refer to a study which demonstrated that umbilical cord occlusion resulted in rapid increase in T/QRS ratio that coincided with initial hypertension and bradycardia at all gestational ages which were tested from 0.6-0.8 gestation. The animals of our study were in this gestational range and, hence, our experimental setup can be used to assess STAN's quality to detect fetal hypoxia. In conclusion, we have clearly demonstrated the appropriateness of using-aVF as a proxy for a scalp electrode-derived signal in STAN in these preterm lambs. Investigation why STAN could not detect relevant ST-changes and instead produced erroneous alarms in our experimental setup is hampered by the fact that the exact STAN algorithm (signal processing and analysis) is not in the public domain.
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Affiliation(s)
- Tammo Delhaas
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
- * E-mail:
| | - Peter Andriessen
- Department of Pediatrics, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Judith OEH van Laar
- Department of Obstetrics and Gynecology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Rik Vullings
- Signal Processing Systems Group, Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Ben JM Hermans
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
| | | | - Reint K. Jellema
- Department of Pediatrics, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Daan RMG Ophelders
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Tim GAM Wolfs
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Boris W. Kramer
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Alex Zwanenburg
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
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Andriessen P, Zwanenburg A, van Laar JOEH, Vullings R, Hermans BJM, Niemarkt HJ, Jellema RK, Ophelders DRMG, Wolfs TGAM, Kramer BW, Delhaas T. ST waveform analysis for monitoring hypoxic distress in fetal sheep after prolonged umbilical cord occlusion. PLoS One 2018; 13:e0195978. [PMID: 29659625 PMCID: PMC5901956 DOI: 10.1371/journal.pone.0195978] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 04/03/2018] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION The inconclusive clinical results for ST-waveform analysis (STAN) in detecting fetal hypoxemia may be caused by the signal processing of the STAN-device itself. We assessed the performance of a clinical STAN device in signal processing and in detecting hypoxemia in a fetal sheep model exposed to prolonged umbilical cord occlusion (UCO). METHODS Eight fetal lambs were exposed to 25 minutes of UCO. ECG recordings were analyzed during a baseline period and during UCO. STAN-event rates and timing of episodic T/QRS rise, baseline T/QRS rise and the occurrence of biphasic ST-waveforms, as well as signal loss, were assessed. RESULTS During baseline conditions of normoxemia, a median of 40 (IQR, 25-70) STAN-events per minute were detected, compared to 10 (IQR, 2-22) during UCO. During UCO STAN-events were detected in five subjects within 10 minutes and in six subjects after 18 minutes, respectively. Two subjects did not generate any STAN-event during UCO. Biphasic ST event rate was reduced during UCO (median 0, IQR 0-5), compared to baseline (median 32, IQR, 6-55). ST-waveforms could not be assessed in 62% of the recording time during UCO, despite a good quality of the ECG signal. CONCLUSIONS The STAN device showed limitations in detecting hypoxemia in fetal sheep after prolonged UCO. The STAN device produced high false positive event rates during baseline and did not detect T/QRS changes adequately after prolonged fetal hypoxemia. During 14% of baseline and 62% of the UCO period, the STAN-device could not process the ECG signal, despite its good quality. Resolving these issues may improve the clinical performance of the STAN device.
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Affiliation(s)
- Peter Andriessen
- Department of Pediatrics, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Alex Zwanenburg
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | | | - Rik Vullings
- Signal Processing Systems group, Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Ben J. M. Hermans
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
| | | | - Reint K. Jellema
- Department of Pediatrics, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Daan R. M. G. Ophelders
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Tim G. A. M. Wolfs
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Boris W. Kramer
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, Maastricht University, Maastricht, the Netherlands
- CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, the Netherlands
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Wassink G, Davidson JO, Dhillon SK, Fraser M, Galinsky R, Bennet L, Gunn AJ. Partial white and grey matter protection with prolonged infusion of recombinant human erythropoietin after asphyxia in preterm fetal sheep. J Cereb Blood Flow Metab 2017; 37:1080-1094. [PMID: 27207167 PMCID: PMC5363482 DOI: 10.1177/0271678x16650455] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Perinatal asphyxia in preterm infants remains a significant contributor to abnormal long-term neurodevelopmental outcomes. Recombinant human erythropoietin has potent non-haematopoietic neuroprotective properties, but there is limited evidence for protection in the preterm brain. Preterm (0.7 gestation) fetal sheep received sham asphyxia (sham occlusion) or asphyxia induced by umbilical cord occlusion for 25 min, followed by an intravenous infusion of vehicle (occlusion-vehicle) or recombinant human erythropoietin (occlusion-Epo, 5000 international units by slow push, then 832.5 IU/h), starting 30 min after asphyxia and continued until 72 h. Recombinant human erythropoietin reduced neuronal loss and numbers of caspase-3-positive cells in the striatal caudate nucleus, CA3 and dentate gyrus of the hippocampus, and thalamic medial nucleus ( P < 0.05 vs. occlusion-vehicle). In the white matter tracts, recombinant human erythropoietin increased total, but not immature/mature oligodendrocytes ( P < 0.05 vs. occlusion-vehicle), with increased cell proliferation and reduced induction of activated caspase-3, microglia and astrocytes ( P < 0.05). Finally, occlusion-Epo reduced seizure burden, with more rapid recovery of electroencephalogram power, spectral edge frequency, and carotid blood flow. In summary, prolonged infusion of recombinant human erythropoietin after severe asphyxia in preterm fetal sheep was partially neuroprotective and improved electrophysiological and cerebrovascular recovery, in association with reduced apoptosis and inflammation.
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Affiliation(s)
- Guido Wassink
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Simerdeep K Dhillon
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Mhoyra Fraser
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand.,2 The Ritchie Centre, Hudson Institute of Medical Research, Clayton, VIC, Australia
| | - Laura Bennet
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- 1 Department of Physiology, The University of Auckland, Auckland, New Zealand
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Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model. Pediatr Res 2016; 79:907-15. [PMID: 26866904 DOI: 10.1038/pr.2016.21] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 11/24/2015] [Indexed: 11/09/2022]
Abstract
BACKGROUND Current methods for assessing perinatal hypoxic conditions did not improve infant outcomes. Various waveform-based and interval-based ECG markers have been suggested, but not directly compared. We compare performance of ECG markers in a standardized ovine model for fetal hypoxia. METHODS Sixty-nine fetal sheep of 0.7 gestation had ECG recorded 4 h before, during, and 4 h after a 25-min period of umbilical cord occlusion (UCO), leading to severe hypoxia. Various ECG markers were calculated, among which were heart rate (HR), HR-corrected ventricular depolarization/repolarization interval (QTc), and ST-segment analysis (STAN) episodic and baseline rise markers, analogue to clinical STAN device alarms. Performance of interval- and waveform-based ECG markers was assessed by correlating predicted and actual hypoxic/normoxic state. RESULTS Of the markers studied, HR and QTc demonstrated high sensitivity (≥86%), specificity (≥96%), and positive predictive value (PPV) (≥86%) and detected hypoxia in ≥90% of fetuses at 4 min after UCO. In contrast, STAN episodic and baseline rise markers displayed low sensitivity (≤20%) and could not detect severe fetal hypoxia in 65 and 28% of the animals, respectively. CONCLUSION Interval-based HR and QTc markers could assess the presence of severe hypoxia. Waveform-based STAN episodic and baseline rise markers were ineffective as markers for hypoxia.
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Galinsky R, Davidson JO, Drury PP, Wassink G, Lear CA, van den Heuij LG, Gunn AJ, Bennet L. Magnesium sulphate and cardiovascular and cerebrovascular adaptations to asphyxia in preterm fetal sheep. J Physiol 2015; 594:1281-93. [PMID: 26077461 DOI: 10.1113/jp270614] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/08/2015] [Indexed: 11/08/2022] Open
Abstract
Magnesium sulphate is a standard therapy for eclampsia in pregnancy and is widely recommended for perinatal neuroprotection during threatened preterm labour. MgSO4 is a vasodilator and negative inotrope. Therefore the aim of this study was to investigate the effect of MgSO4 on the cardiovascular and cerebrovascular responses of the preterm fetus to asphyxia. Fetal sheep were instrumented at 98 ± 1 days of gestation (term = 147 days). At 104 days, unanaesthetised fetuses were randomly assigned to receive an intravenous infusion of MgSO4 (n = 6) or saline (n = 9). At 105 days all fetuses underwent umbilical cord occlusion for 25 min. Before occlusion, MgSO4 treatment reduced heart rate and increased femoral blood flow (FBF) and vascular conductance compared to controls. During occlusion, carotid and femoral arterial conductance and blood flows were higher in MgSO4-treated fetuses than controls. After occlusion, fetal heart rate was lower and carotid and femoral arterial conductance and blood flows were higher in MgSO4-treated fetuses than controls. Femoral arterial waveform height and width were increased during MgSO4 infusion, consistent with increased stroke volume. MgSO4 did not alter the fetal neurophysiological or nuchal electromyographic responses to asphyxia. These data demonstrate that a clinically comparable dose of MgSO4 increased FBF and stroke volume without impairing mean arterial pressure (MAP) or carotid blood flow (CaBF) during and immediately after profound asphyxia. Thus, MgSO4 may increase perfusion of peripheral vascular beds during adverse perinatal events.
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Affiliation(s)
- Robert Galinsky
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Paul P Drury
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Christopher A Lear
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | | | - Alistair J Gunn
- The Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- The Department of Physiology, University of Auckland, Auckland, New Zealand
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Lear CA, Galinsky R, Wassink G, Mitchell CJ, Davidson JO, Westgate JA, Bennet L, Gunn AJ. Sympathetic neural activation does not mediate heart rate variability during repeated brief umbilical cord occlusions in near-term fetal sheep. J Physiol 2015; 594:1265-77. [PMID: 25864517 DOI: 10.1113/jp270125] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 04/07/2015] [Indexed: 11/08/2022] Open
Abstract
Changes in fetal heart rate variability (FHRV) and ST segment elevation (measured as the T/QRS ratio) are used to evaluate fetal adaptation to labour. The sympathetic nervous system (SNS) is an important contributor to FHRV under healthy normoxic conditions, and is critical for rapid support of blood pressure during brief labour-like asphyxia. However, although it has been assumed that SNS activity contributes to FHRV during labour; this has never been tested, and it is unclear whether the SNS contributes to the rapid increase in T/QRS ratio during brief asphyxia. Thirteen chronically instrumented fetal sheep at 0.85 of gestation received either chemical sympathectomy with 6-hydroxydopamine (6-OHDA; n = 6) or sham treatment (control; n = 7), followed 4-5 days later by 2 min episodes of complete umbilical cord occlusion repeated every 5 min for up to 4 h, or until mean arterial blood pressure fell to <20 mmHg for two successive occlusions. FHRV was decreased before occlusions in the 6-OHDA group (P < 0.05) and 2-4.5 h during recovery after occlusions (P < 0.05) compared to the control group. During each occlusion there was a rapid increase in T/QRS ratio. Between successive occlusions the T/QRS ratio rapidly returned to baseline, and FHRV increased above baseline in both groups (P < 0.05), with no significant effect of sympathectomy on FHRV or T/QRS ratio. In conclusion, these data show that SNS activity does not mediate the increase in FHRV between repeated episodes of brief umbilical cord occlusion or the transient increase in T/QRS ratio during occlusions.
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Affiliation(s)
- Christopher A Lear
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Robert Galinsky
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Guido Wassink
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Clinton J Mitchell
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Joanne O Davidson
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Jennifer A Westgate
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Laura Bennet
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Alistair J Gunn
- The Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand
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