The authors thank Kathy Gage for her editorial support. This study was supported by funds from the Department of Anesthesiology (Duke University Medical Center), American Heart Association grant (18CSA34080277), and National Institutes of Health (NIH) grants (NS099590, HL157354, NS117973, and NS127163).

All the procedures described here were conducted in accordance with the National Institutes of Health (NIH) guidelines for the care and use of animals in research, and the protocol was approved by the Duke Institute of Animal Care and Use Committee (IACUC). C57BL/6 male and female&#160;mice aged 8-10 weeks old were used for the present study.
1. Surgical preparation
<ol>
	<li>Weigh a mouse on a digital scale, and place it into a 4 in x 4 in x 7 in plexiglass anesthesia induc...

A Mouse Model to Study Brain Physiology During Cardiac Arrest

<ol>
	<li>Smith, A., Masters, S., Ball, S., Finn, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+incidence+and+outcomes+of+out-of-hospital+cardiac+arrest+in+metropolitan+versus+rural+locations:+A+systematic+review+and+meta-analysis.">The incidence and outcomes of out-of-hospital cardiac arrest in metropolitan versus rural locations: A systematic review and meta-analysis.</a> Resuscitation. 185, 109655 (2022).</li><li>Amacher, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predicting+neurological+outcome+in+adult+patients+with+cardiac+arrest:+systematic+review+and+meta-analysis+of+prediction+model+performance.">Predicting neurological outcome in adult patients with cardiac arrest: systematic review and meta-analysis of prediction model performance.</a> Critical Care. 26 (1), 382 (2022).</li><li>Matsuyama, T., Ohta, B., Kiyohara, K., Kitamura, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intra-arrest+partial+carbon+dioxide+level+and+favorable+neurological+outcome+after+out-of-hospital+cardiac+arrest:+A+nationwide+multicenter+observational+study+in+Japan+(the+JAAM-OHCA+registry).">Intra-arrest partial carbon dioxide level and favorable neurological outcome after out-of-hospital cardiac arrest: A nationwide multicenter observational study in Japan (the JAAM-OHCA registry).</a> European Heart Journal of Acute Cardiovascular Care. 12 (1), 14-21 (2023).</li><li>Takahagi, M., Sawano, H., Moriyama, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-term+neurological+outcome+of+extracorporeal+cardiopulmonary+resuscitation+for+out-of-hospital+cardiac+arrest+patients+with+nonshockable+rhythms:+A+single-center,+consecutive,+retrospective+observational+study.">Long-term neurological outcome of extracorporeal cardiopulmonary resuscitation for out-of-hospital cardiac arrest patients with nonshockable rhythms: A single-center, consecutive, retrospective observational study.</a> The Journal of Emergency Medicine. 63 (3), 367-375 (2022).</li><li>Mork, S. R., Botker, M. T., Christensen, S., Tang, M., Terkelsen, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Survival+and+neurological+outcome+after+out-of-hospital+cardiac+arrest+treated+with+and+without+mechanical+circulatory+support.">Survival and neurological outcome after out-of-hospital cardiac arrest treated with and without mechanical circulatory support.</a> Resuscition Plus. 10, 100230 (2022).</li><li>Koenig, M. A., Kaplan, P. W., Thakor, N. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+neurophysiologic+monitoring+and+brain+injury+from+cardiac+arrest.">Clinical neurophysiologic monitoring and brain injury from cardiac arrest.</a> Neurologic Clinics. 24 (1), 89-106 (2006).</li><li>Cavazzoni, E., Schibler, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+of+brain+tissue+oxygen+tension+and+use+of+vasopressin+after+cardiac+arrest+in+a+child+with+catecholamine-induced+cardiac+arrhythmia.">Monitoring of brain tissue oxygen tension and use of vasopressin after cardiac arrest in a child with catecholamine-induced cardiac arrhythmia.</a> Critical Care &amp; Resuscitation. 10 (4), 316-319 (2008).</li><li>Topjian, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multimodal+monitoring+including+early+EEG+improves+stratification+of+brain+injury+severity+after+pediatric+cardiac+arrest.">Multimodal monitoring including early EEG improves stratification of brain injury severity after pediatric cardiac arrest.</a> Resuscitation. 167, 282-288 (2021).</li><li>Beekman, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bedside+monitoring+of+hypoxic+ischemic+brain+injury+using+low-field,+portable+brain+magnetic+resonance+imaging+after+cardiac+arrest.">Bedside monitoring of hypoxic ischemic brain injury using low-field, portable brain magnetic resonance imaging after cardiac arrest.</a> Resuscitation. 176, 150-158 (2022).</li><li>Sinha, N., Parnia, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monitoring+the+brain+after+cardiac+arrest:+A+new+era.">Monitoring the brain after cardiac arrest: A new era.</a> Current Neurology Neuroscience Report. 17 (8), 62 (2017).</li><li>Reis, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiology+and+the+monitoring+methods+for+cardiac+arrest+associated+brain+injury.">Pathophysiology and the monitoring methods for cardiac arrest associated brain injury.</a> International Journal of Molecular Sciences. 18 (1), 129 (2017).</li><li>Zhou, H., Lin, C., Liu, J., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+monitoring+of+brain+perfusion+by+cerebral+oximetry+after+spontaneous+return+of+circulation+in+cardiac+arrest:+A+case+report.">Continuous monitoring of brain perfusion by cerebral oximetry after spontaneous return of circulation in cardiac arrest: A case report.</a> BMC Neurology. 22 (1), 365 (2022).</li><li>Takegawa, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+brain+monitoring+by+near-infrared+spectroscopy+predicts+neurological+outcome+after+cardiac+arrest+and+resuscitation+in+rats:+A+proof+of+concept+study+of+a+novel+prognostic+measure+after+cardiac+arrest.">Real-time brain monitoring by near-infrared spectroscopy predicts neurological outcome after cardiac arrest and resuscitation in rats: A proof of concept study of a novel prognostic measure after cardiac arrest.</a> Journal Clinical Medicine. 11 (1), 131 (2021).</li><li>Zhang, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Invasion+of+peripheral+immune+cells+into+brain+parenchyma+after+cardiac+arrest+and+resuscitation.">Invasion of peripheral immune cells into brain parenchyma after cardiac arrest and resuscitation.</a> Aging and Disease. 9 (3), 412-425 (2018).</li><li>Duan, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cervical+vagus+nerve+stimulation+improves+neurologic+outcome+after+cardiac+arrest+in+mice+by+attenuating+oxidative+stress+and+excessive+autophagy.">Cervical vagus nerve stimulation improves neurologic outcome after cardiac arrest in mice by attenuating oxidative stress and excessive autophagy.</a> Neuromodulation. 25 (3), 414-423 (2022).</li><li>Liu, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+modification+of+potassium+chloride+induced+cardiac+arrest+model+for+aged+mice.">Novel modification of potassium chloride induced cardiac arrest model for aged mice.</a> Aging and Disease. 9 (1), 31-39 (2018).</li><li>Shen, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aging+is+associated+with+impaired+activation+of+protein+homeostasis-related+pathways+after+cardiac+arrest+in+mice.">Aging is associated with impaired activation of protein homeostasis-related pathways after cardiac arrest in mice.</a> Journal of American Heart Association. 7 (17), e009634 (2018).</li><li>Wang, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manganese+porphyrin+promotes+post+cardiac+arrest+recovery+in+mice+and+rats.">Manganese porphyrin promotes post cardiac arrest recovery in mice and rats.</a> Biology. 11 (7), 957 (2022).</li><li>Wang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+evaluation+of+a+novel+mouse+model+of+asphyxial+cardiac+arrest+revealed+severely+impaired+lymphopoiesis+after+resuscitation.">Development and evaluation of a novel mouse model of asphyxial cardiac arrest revealed severely impaired lymphopoiesis after resuscitation.</a> Journal of American Heart Association. 10 (11), e019142 (2021).</li><li>Li, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+the+XBP1s/O-GlcNAcylation+pathway+improves+functional+outcome+after+cardiac+arrest+and+resuscitation+in+young+and+aged+mice.">Activation of the XBP1s/O-GlcNAcylation pathway improves functional outcome after cardiac arrest and resuscitation in young and aged mice.</a> Shock. 56 (5), 755-761 (2021).</li><li>Shen, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Activation+of+the+ATF6+(activating+transcription+factor+6)+signaling+pathway+in+neurons+improves+outcome+after+cardiac+arrest+in+mice.">Activation of the ATF6 (activating transcription factor 6) signaling pathway in neurons improves outcome after cardiac arrest in mice.</a> Journal American Heart Association. 10 (12), e020216 (2021).</li><li>Jiang, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MCC950,+a+selective+NLPR3+inflammasome+inhibitor,+improves+neurologic+function+and+survival+after+cardiac+arrest+and+resuscitation.">MCC950, a selective NLPR3 inflammasome inhibitor, improves neurologic function and survival after cardiac arrest and resuscitation.</a> Journal of Neuroinflammation. 17 (1), 256 (2020).</li><li>Zhao, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+arrest+and+resuscitation+activates+the+hypothalamic-pituitary-adrenal+axis+and+results+in+severe+immunosuppression.">Cardiac arrest and resuscitation activates the hypothalamic-pituitary-adrenal axis and results in severe immunosuppression.</a> Journal of Cerebral Blood Flow &amp; Metabolism. 41 (5), 1091-1102 (2021).</li></ol>

In experimental CA studies, asphyxia, potassium chloride injections, or electrical current-derived ventricular fibrillation have been used to induce CA16,17,18,19,20,21,22,23. Normally, CPR is required for resuscitation in these CA models, especially in mic...

Cardiac arrest (CA) remains a global public health crisis1. More than 356,000 out-of-hospital and 290,000 in-hospital CA cases are reported annually in the US alone, and most CA victims are over 60 years old. Notably, post-CA neurologic impairments are common among survivors, and these represent a major challenge for CA management2,3,4,5. To understand post-CA brain pathologic changes and their effects on neurologic outcomes, various neurophysiologic monitoring and brain tissue monitoring techniques have been applied in patients6,7,8,9,10,11,12. Using near-infrared spectroscopy, real-time brain monitoring has also been performed in CA rats to predict neurologic outcomes13.
However, in murine CA models, such an imaging approach has been complicated by the need for chest compressions to restore spontaneous circulation, which always entails substantial physical motion and, thus, hinders delicate imaging procedures. Moreover, CA models are normally performed with mice in a supine position, whereas the mice must be turned to the prone position for many brain imaging modalities. Thus, a mouse model with minimal body movement during the surgery is required in many cases in order to perform real-time imaging/monitoring of the brain during the whole CA procedure, spanning from pre-CA to post-resuscitation.
Previously, Zhang et al. reported a mouse CA model that could be useful for brain imaging14. In their model, CA was induced by bolus injections of vecuronium and esmolol followed by the cessation of mechanical ventilation. They showed that after 5 min of CA, resuscitation could be achieved by infusing a resuscitation mixture. Notably, however, circulatory arrest in their model occurred only about 10 s after the esmolol injection. Thus, this model does not recapitulate the progression of asphyxia-induced CA in patients, including hypercapnia and tissue hypoxia during the prearrest period.
The overall goal of the current surgical procedure is to model clinical asphyxia CA in mice followed by resuscitation without chest compressions. This CA model, therefore, allows the use of complex imaging techniques to study brain physiology in mice15.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Adrenalin</td>
			<td >Par Pharmaceutical</td>
			<td >NDC 42023-159-01</td>
			<td ></td>
		</tr>
		<tr >
			<td >Alcohol swabs</td>
			<td >BD</td>
			<td >326895</td>
			<td></td>
		</tr>
		<tr >
			<td >Animal Bio Amp</td>
			<td >ADInstruments</td>
			<td >FE232</td>
			<td></td>
		</tr>
		<tr >
			<td >BP transducer</td>
			<td >ADInstruments</td>
			<td >MLT0699</td>
			<td></td>
		</tr>
		<tr >
			<td >Bridge Amp</td>
			<td >ADInstruments</td>
			<td >FE117</td>
			<td></td>
		</tr>
		<tr >
			<td >Heparin sodium injection, USP</td>
			<td >Fresenius Kabi</td>
			<td >NDC 63323-540-05</td>
			<td></td>
		</tr>
		<tr >
			<td >Isoflurane</td>
			<td >Covetrus</td>
			<td >NDC 11695-6777-2</td>
			<td></td>
		</tr>
		<tr >
			<td >Laser Doppler perfusion monitor</td>
			<td >Moor Instruments</td>
			<td >moorVMS-LDF1</td>
			<td></td>
		</tr>
		<tr >
			<td >Laser speckle imaging system</td>
			<td >RWD</td>
			<td >RFLSI III</td>
			<td></td>
		</tr>
		<tr >
			<td >Lubricant eye ointment</td>
			<td >Bausch + Lomb</td>
			<td >339081</td>
			<td></td>
		</tr>
		<tr >
			<td >Micro clip</td>
			<td >Roboz</td>
			<td >RS-5431</td>
			<td></td>
		</tr>
		<tr >
			<td >Mouse rectal probe</td>
			<td >Physitemp</td>
			<td >RET-3</td>
			<td></td>
		</tr>
		<tr >
			<td >Needle electrode</td>
			<td >ADInstruments</td>
			<td >MLA1213</td>
			<td>29 Ga, 1.5 mm socket</td>
		</tr>
		<tr >
			<td >Nitrogen</td>
			<td >Airgas</td>
			<td >UN1066</td>
			<td></td>
		</tr>
		<tr >
			<td >Optic plastic fibre</td>
			<td >Moor Instruments</td>
			<td >POF500</td>
			<td></td>
		</tr>
		<tr >
			<td >Otoscope</td>
			<td >Welchallyn</td>
			<td >728</td>
			<td>2.5 mm Speculum</td>
		</tr>
		<tr >
			<td >Oxygen</td>
			<td >Airgas</td>
			<td >UN1072</td>
			<td></td>
		</tr>
		<tr >
			<td >PE-10 tubing</td>
			<td >BD</td>
			<td >427401</td>
			<td>Polyethylene tubing</td>
		</tr>
		<tr >
			<td >Povidone-iodine</td>
			<td >CVS</td>
			<td >955338</td>
			<td></td>
		</tr>
		<tr >
			<td >PowerLab 8/35</td>
			<td >ADInstruments</td>
			<td ></td>
			<td></td>
		</tr>
		<tr >
			<td >Rimadyl (carprofen)</td>
			<td >Zoetis</td>
			<td >6100701</td>
			<td>Injectable 50 mg/ml</td>
		</tr>
		<tr >
			<td >Small animal ventilator</td>
			<td >Kent Scientific</td>
			<td >RoVent Jr.</td>
			<td></td>
		</tr>
		<tr >
			<td >Temperature controller</td>
			<td >Physitemp</td>
			<td >TCAT-2DF</td>
			<td></td>
		</tr>
		<tr >
			<td >Triple antibioric &#38; pain relief</td>
			<td >CVS</td>
			<td >NDC 59770-823-56</td>
			<td></td>
		</tr>
		<tr >
			<td >Vaporizer</td>
			<td >RWD</td>
			<td >R583S</td>
			<td></td>
		</tr>
		<tr >
			<td >0.25% bupivacaine</td>
			<td >Hospira</td>
			<td >NDC 0409-1159-18</td>
			<td></td>
		</tr>
		<tr >
			<td >0.9% sodium chroride</td>
			<td >ICU Medical</td>
			<td >NDC 0990-7983-03</td>
			<td></td>
		</tr>
		<tr >
			<td >1 mL plastic syringe</td>
			<td >BD</td>
			<td >309659</td>
			<td></td>
		</tr>
		<tr >
			<td >4-0 silk suture</td>
			<td >Look</td>
			<td >SP116</td>
			<td>Black braided silk</td>
		</tr>
		<tr >
			<td >6-0 nylon suture</td>
			<td >Ethilon</td>
			<td >1698G</td>
			<td></td>
		</tr>
		<tr >
			<td >8.4% sodium bicarbonate Inj., USP</td>
			<td >Hospira</td>
			<td >NDC 0409-6625-02</td>
			<td></td>
		</tr>
		<tr >
			<td >20 G IV catheter</td>
			<td >BD</td>
			<td >381534</td>
			<td>20GA 1.6 IN</td>
		</tr>
		<tr >
			<td >30 G PrecisionGlide needle</td>
			<td >BD</td>
			<td >305106</td>
			<td>30 G X 1/2</td>
		</tr>
	</tbody>
</table>

mouse cardiac arrest model for brain imaging and brain physiology monitoring during ischemia and resuscitation

Most cardiac arrest (CA) survivors experience varying degrees of neurologic deficits. To understand the mechanisms that underpin CA-induced brain injury and, subsequently, develop effective treatments, experimental CA research is essential. To this end, a few mouse CA models have been established. In most of these models, the mice are placed in the supine position in order to perform chest compression for cardiopulmonary resuscitation (CPR). However, this resuscitation procedure makes the real-time imaging/monitoring of brain physiology during CA and resuscitation challenging. To obtain such critical knowledge, the present protocol presents a mouse asphyxia CA model that does not require the chest compression CPR step. This model allows for the study of dynamic changes in blood flow, vascular structure, electrical potentials, and brain tissue oxygen from the pre-CA baseline to early post-CA reperfusion. Importantly, this model applies to aged mice. Thus, this mouse CA model is expected to be a critical tool for deciphering the impact of CA on brain physiology.

Author Spotlight: A Unique Mouse Model of Asphyxia-Induced Cardiac Arrest 

Mouse Cardiac Arrest Model for Brain Imaging and Brain Physiology Monitoring During Ischemia and Resuscitation

Cardiac arrest affects over half a million people in the US every year, leading to impaired neurological function primarily caused by hypoxic-ischemic brain injury. To develop better treatments, we aim to understand how cardiac arrest affects brain physiology, including microcirculatory blood flow and oxygen use, through experimental research. Advanced imaging and the monitoring methods have been established to investigate the cerebral blood flow after cardiac arrest.However, obtaining a complete image of cerebral circulation during cardiac arrest and early resuscitation remains challenging. Our protocol involves simulating clinical asphyxia-induced cardiac arrest in mice, followed by recitation without chest compressions. This model enables the use of advanced imaging methods to study brain physiology in mice throughout the cardiac arrest process.This model does not require complex surgical interventions, and is relatively easier to perform. More importantly, during cardiac arrest and resuscitation, animals can be kept in prone proposition with minimal animal movement, which greatly facilitates the use of various imaging modalities. The impact of cardiac arrest and its treatment strategies, such as epinephrine administration, brain hemodynamics and the neurological function, is not yet fully understood.Our mouse model is ideal for investigating the dynamic alterations in brain circulation, vascular responses, and brain tissue oxygenation that occur during a cardiac arrest and resuscitation.

To induce CA, the mouse was anesthetized with 1.5% isoflurane and ventilated with 100% nitrogen. This condition led to severe bradycardia in 45 s (Figure 1). Following 2 min of anoxia, the heart rate dramatically reduced (Figure 2), the blood pressure decreased below 20 mmHg, and the cerebral blood flow ceased completely (Figure 1).&#160;As the isoflurane was turned off, the body temperature was no longer managed and slowly dropped ...

Watch this Scientific Journal Video about A Unique Mouse Model of Asphyxia-Induced Cardiac Arrest at JoVE.com

This protocol demonstrates a unique mouse model of asphyxia cardiac arrest that does not require chest compression for resuscitation. This model is useful for monitoring and imaging the dynamics of brain physiology during cardiac arrest and resuscitation.

Most cardiac arrest (CA) survivors experience varying degrees of neurologic deficits. To understand the mechanisms that underpin CA-induced brain injury ...