Prognostic Significance of Signs of Life in Out-of-Hospital Cardiac Arrest Patients Undergoing Extracorporeal Cardiopulmonary Resuscitation.

OBJECTIVES: Signs of life (SOLs) during cardiac arrest (gasping, pupillary light reaction, or any form of body movement) are suggested to be associated with favorable neurologic outcomes in out-of-hospital cardiac arrest (OHCA). While data has demonstrated that extracorporeal cardiopulmonary resuscitation (ECPR) can improve outcomes in cases of refractory cardiac arrest, it is expected that other contributing factors lead to positive outcomes. This study aimed to investigate whether SOL on arrival is associated with neurologic outcomes in patients with OHCA who have undergone ECPR. DESIGN: Retrospective multicenter registry study. SETTING: Thirty-six facilities participating in the Study of Advanced life support for Ventricular fibrillation with Extracorporeal circulation in Japan II (SAVE-J II). PATIENTS: Consecutive patients older than 18 years old who were admitted to the Emergency Department with OHCA between January 1, 2013, and December 31, 2018, and received ECPR. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were classified into two groups according to the presence or absence of SOL on arrival. The primary outcome was a favorable neurologic outcome (Cerebral Performance Category 1 or 2) at discharge. Of the 2157 patients registered in the SAVE-J II database, 1395 met the inclusion criteria, and 250 (17.9%) had SOL upon arrival. Patients with SOL had more favorable neurologic outcomes than those without SOL (38.0% vs. 8.1%; p < 0.001). Multivariate analysis showed that SOL on arrival was independently associated with favorable neurologic outcomes (odds ratio, 5.65 [95% CI, 3.97-8.03]; p < 0.001). CONCLUSIONS: SOL on arrival was associated with favorable neurologic outcomes in patients with OHCA undergoing ECPR. In patients considered for ECPR, the presence of SOL on arrival can assist the decision to perform ECPR.

Cases of prolonged cardiac arrest with preserved gasping successfully resuscitated with ECPR.

Longer cardiopulmonary resuscitation (CPR) time is associated with worsened neurological outcomes in out-of-hospital cardiac arrest (OHCA). Gasping during CPR is a favorable neurological predictor for OHCA. Recently, the efficacy of extracorporeal cardiopulmonary resuscitation (ECPR) in refractory cardiac arrest has been reported. However, the significance of gasping in refractory cardiac arrest patients with long CPR durations treated with ECPR is still unclear. We report two cases of cardiac arrest with gasping that were successfully resuscitated by ECPR, despite extremely long low-flow times. In case 1, a 58-year-old man presented with cardiac arrest and ventricular fibrillation (VF). Gasping was observed when the patient arrived at the hospital. ECPR was initiated 82 min after cardiac arrest. The patient was diagnosed with hypertrophic cardiomyopathy. ECMO was withdrawn on day 4, and the patient was discharged without neurological impairment. In case 2, a 49-year-old man experienced cardiac arrest with VF, and his gasping was preserved during transportation. On arrival, VF persisted, and gasping was observed; therefore, ECMO was initiated 93 min after cardiac arrest. He was diagnosed with acute myocardial infarction. ECMO was withdrawn on day 4 and he was discharged from the hospital without any neurological impairment. Resuscitation and ECPR should not be abandoned in case of preserved gasping, even when the low-flow time is extremely long.

Risk factors for acute pancreatitis in patients with accidental hypothermia.

BACKGROUND: Pancreatic damage is commonly observed as a consequence of accidental hypothermia (core body temperature below 35 °C). We aimed to investigate the risk factors for pancreatic damage and the causal relationship in patients with accidental hypothermia. METHODS: This retrospective, single-center, observational case-control study was conducted in the emergency department of a tertiary care medical center. We investigated patients who were admitted for accidental hypothermia over a course of ten years (January 2008 to December 2017). RESULTS: Of the 138 enrolled patients, 70 had elevated serum amylase levels (51%). We observed a correlation between initial core body temperature and serum amylase level (Spearman's rank correlation coefficient -0.302, p < 0.001). Patients who developed acute pancreatitis had a significantly lower initial core body temperature than those who did not develop it (odds ratio = 0.76; 95% confidence interval [CI] = 0.61-0.94; p = 0.011). Receiver operating characteristic analysis showed that a body temperature lower than 28.5 °C at the time of visit was predictive of acute pancreatitis (area under the curve = 0.71, 95% CI = 0.54-0.88, sensitivity = 0.67, specificity = 0.69, p = 0.017). CONCLUSIONS: We concluded that an initial core body temperature lower than 28.5 °C was a risk factor for acute pancreatitis in accidental hypothermia cases. In such situations, careful follow-up is necessary.

CT Imaging Before Extracorporeal Cardiopulmonary Resuscitation in Hypothermic Cardiac Arrest With Trauma.

Hypothermic cardiac arrest (HCA) with concomitant trauma presents a significant clinical management challenge. In these case reports, computed tomography (CT) imaging was performed before extracorporeal cardiopulmonary resuscitation (ECPR) in patients with cardiac arrest, accidental hypothermia, and trauma. The first case involved a 74-year-old male who collapsed outside his home under freezing conditions. Upon arrival at the emergency department (ED), he was in cardiac arrest with a core body temperature of 25.0°C and suspected head trauma. CT imaging revealed minor traumatic brain injuries and bilateral femoral fractures. ECPR was initiated after CT imaging, which led to successful rewarming and full neurological recovery. The second case describes a 32-year-old female who jumped from a bridge, experienced cardiac arrest during the rescue, and had a core temperature of 17.4°C. CT imaging before ECPR revealed no significant trauma. Despite prolonged resuscitation, the patient showed a complete neurological recovery. CT imaging before ECPR allows appropriate patient selection by ruling out cardiac arrest before hypothermia and major hemorrhagic complications. Hypothermic cardiac arrest may be acceptable for prolonged resuscitation time on CT imaging owing to reduced cerebral metabolism. These rare case reports demonstrate the potential benefits of CT imaging before ECPR in the management of hypothermic cardiac arrest with trauma and aid in appropriate candidate selection and effective intervention without compromising neurological outcomes.

Sepsis-induced modulation of long-term potentiation induced by theta burst stimulation in the rat hippocampus.

We investigated the influences of sepsis on central synaptic plasticity in vitro. Cecal ligation and puncture (CLP) was performed by creating rat sepsis models, which were divided into early and late sepsis groups (8 and 16 h after CLP, respectively). In the CA1 of the rat hippocampal slices, orthodromically elicited population spikes (PSs) and field excitatory postsynaptic potentials (fEPSPs) were simultaneously recorded, and their long-term potentiation (LTP) was induced by theta burst stimulation (TBS). TBS induced LTPs of PSs and fEPSPs in all groups. In the sham and early sepsis groups, there was no significant difference in LTPs between PSs and fEPSPs. However, in the late sepsis group, the LTP of PSs was greater than that of fEPSPs (p < 0.05) and was greater than the LTPs of PSs in the sham and early sepsis groups (p < 0.05). Superoxide dismutase, administered immediately before CLP, inhibited the enhancement of LTP in PS, as observed in the late sepsis group. The initial rapid potentiation component of LTP in fEPSPs was suppressed or reduced in all groups that underwent CLP. The results indicate that CLP-induced sepsis modulates hippocampal synaptic plasticity, depressing excitatory synaptic transmissions and facilitating somatic excitability, which is induced by septic oxygen superoxide.

Tazobactam/ceftolozane and tobramycin combination therapy in extensively drug-resistant Pseudomonas aeruginosa infections in severe burn injury: a case report.

BACKGROUND: Combination therapy with tazobactam/ceftolozane (TAZ/CTLZ) and high-dose aminoglycosides has been reported to be efficacious in extensively drug-resistant (XDR)-Pseudomonas aeruginosa infection. However, there are no reports of efficacy in XDR-P. aeruginosa infection for combination therapy with low-dose aminoglycosides and TAZ/CTLZ. Herein, we describe a rare case of severe burn injury patients with persistent bacteremia due to XDR-P. aeruginosa, which was successfully treated with TAZ/CTLZ and low-dose tobramycin (TOB). CASE PRESENTATION: A 31-year-old man was admitted to the intensive care unit with severe burn injury involving 52% of the total body surface area and a prognostic burn index of 79.5. The patient had recurrent bacterial infections since admission, and blood cultures collected on the 37th day of admission revealed the presence of P. aeruginosa strains that were resistant to all ß-lactams and amikacin (AMK). The results of the antimicrobial synergistic study showed no synergistic effect of low-dose meropenem (MEPM) and AMK combination therapy. The patient had acute renal failure, and it was difficult to increase the dose of MEPM and AMK, respectively. Thus, we initiated TAZ/CTLZ 1.5 g/8 h instead of the AMK and MEPM combination therapy on the 43rd day of hospitalization. Low-dose TAZ/CTLZ was continued because of prolonged renal dysfunction and resulted in a transient clinical improvement. However, the dosage of TAZ/CTLZ could be increased as the renal function improved, but despite an increased TAZ/CTLZ dose, bacteremia persisted, and the blood cultures remained positive. Thus, TOB was added to TAZ/CTLZ at low doses for synergistic effect against Gram-negative bacteria. Blood cultures collected after initiation of combination therapy with TAZ/CTLZ and low-dose TOB were negative on two consecutive follow-up evaluations. Thereafter, although the patient had several episodes of fever and increased inflammatory response, blood cultures consistently tested negative, and all of the wounds healed. On the 93rd day, due to the good healing progress, the patient was transferred to another hospital. CONCLUSIONS: TAZ/CTLZ and low-dose TOB combination therapy showed the potential for synergistic effects. Our present report suggests a novel synergistic treatment strategy for rare cases that are refractory to the treatment of infections, such as XDR-P. aeruginosa infection.

A 48-Year-Old Previously Healthy Man Presenting with Acute Respiratory Distress Syndrome (ARDS), Negative Tests for SARS-CoV-2, and Positive Serology for Parainfluenza Virus Type 3 (PIV-3).

BACKGROUND Human parainfluenza viruses (PIVs) belong to the Paramyxoviridae family. PIVs cause lower respiratory tract infections in children and the elderly. In addition, severe pneumonia due to PIVs has been reported in immunocompromised adults. However, no reports have described PIV infections leading to acute respiratory distress syndrome (ARDS) in immunocompetent hosts. CASE REPORT A 48-year-old otherwise healthy man was transported to our hospital due to worsening dyspnea. On arrival, strong effortful breathing was observed and results of arterial blood gas analysis revealed severe hypoxia. On the basis of the clinical presentation, we intubated the patient for mechanical ventilation. However, mechanical ventilation provided inadequate oxygenation. Finally, veno-venous extracorporeal membrane oxygenation was initiated. Pneumonia was considered to be a cause of the ARDS, based on the patient's history and blood examination. Repeated reverse transcription-polymerase chain reaction tests for the novel coronavirus were performed, and endotracheal aspirate specimens were cultured for bacteria and fungus; however, the results were all negative. On day 2, the PIV-3-specific antibody titer was elevated. Two weeks later, the PIV-3-specific antibody titer had increased 4-fold. On the basis of these results, we diagnosed pneumonia induced by PIV-3 infection. CONCLUSIONS ARDS can occur because of severe pneumonia induced by PIV-3. In cases of unexplained severe pneumonia or ARDS, PIV infection should be included in the differential diagnosis.

Dexmedetomidine improves excessive extracellular glutamate-induced synaptic depression (BRAINRES-D-21-00941).

We investigated the effects of dexmedetomidine, a selective α2-adrenergic agonist and a sedative, on excessive glutamate-induced depressions of central excitatory synaptic transmissions in vitro. From the CA1 in rat hippocampal slices, orthodromically elicited population spikes (PSs) and field excitatory postsynaptic potentials (fEPSPs) at 0.1 Hz were simultaneously recorded. ANOVA was used for statistics, and p < 0.05 was accepted as significant. Glutamate (10 mM for 10 min) completely depressed PSs and fEPSPs, which were partially recovered by the following washout for 40 min (57.4 ± 10.2% and 59.9 ± 9.8% of the control, respectively, p < 0.01, n = 6). The recoveries in PSs and fEPSPs were improved by pre-treatment and simultaneous treatment with dexmedetomidine (p < 0.01, n = 6) but were not altered by post-treatment. Dexmedetomidine alone did not alter PSs and fEPSPs. Simultaneous treatment with isoproterenol or dobutamine exacerbated the recoveries in PSs and fEPSPs (p < 0.01, n = 6), but simultaneous treatment with salbutamol, propranolol, phenylephrine or phentramine did not influence the recoveries. Simultaneous treatment with AP5 improved the recoveries in PSs and fEPSPs that were depressed by glutamate alone and by glutamate with dexmedetomidine, isoproterenol or dobutamine (p < 0.01, n = 6). Excessive glutamate depresses glutamatergic excitatory synaptic transmissions by mainly mediating NMDA receptors, and the depressed transmissions are improved by α2-adrenoceptor stimulation but are exacerbated by ß1-adrenoceptor stimulation. Dexmedetomidine has a protective effect on neuronal dysfunctions induced by excessive glutamate, which is one of the main mechanisms of the secondary damage in the central nervous system.

Disseminated mucormycosis in a patient with severe COVID-19 on venovenous extracorporeal membrane oxygenation: A case report.

Background: Since the global outbreak of coronavirus disease 2019 (COVID-19), there have been several reports of mucormycosis as a secondary complication. However, the disseminated type of mucormycosis is extremely rare. Case: A 58-year-old male patient with COVID-19 started receiving venovenous extracorporeal membrane oxygenation because of severe respiratory failure. During hospitalization, intra-abdominal hemorrhage occurred and an emergency laparotomy was performed. Subsequently, the patient suffered septic shock, and part of the small intestines and the abdominal wall became necrotic. Finally, the patient died. At autopsy, he was diagnosed with disseminated mucormycosis. Conclusion: Disseminated mucormycosis should be considered in patients with COVID-19 with refractory sepsis unresponsive to broad-spectrum antimicrobial therapy.

Correlation between the hysteresis of the pressure-volume curve and the recruitment-to-inflation ratio in patients with coronavirus disease 2019.

BACKGROUND: Since the response to lung recruitment varies greatly among patients receiving mechanical ventilation, lung recruitability should be assessed before recruitment maneuvers. The pressure-volume curve (PV curve) and recruitment-to-inflation ratio (R/I ratio) can be used bedside for evaluating lung recruitability and individualing positive end-expiratory pressure (PEEP). Lung tissue recruitment on computed tomography has been correlated with normalized maximal distance (NMD) of the quasi-static PV curve. NMD is the maximal distance between the inspiratory and expiratory limb of the PV curve normalized to the maximal volume. However, the relationship between the different parameters of hysteresis of the quasi-static PV curve and R/I ratio for recruitability is unknown. METHODS: We analyzed the data of 33 patients with severe coronavirus disease 2019 (COVID-19) who received invasive mechanical ventilation. Respiratory waveform data were collected from the ventilator using proprietary acquisition software. We examined the relationship of the R/I ratio, quasi-static PV curve items such as NMD, and respiratory system compliance (Crs). RESULTS: The median R/I ratio was 0.90 [interquartile range (IQR), 0.70-1.15] and median NMD was 41.0 [IQR, 37.1-44.1]. The NMD correlated significantly with the R/I ratio (rho = 0.74, P < 0.001). Sub-analysis showed that the NMD and R/I ratio did not correlate with Crs at lower PEEP (- 0.057, P = 0.75; and rho = 0.15, P = 0.41, respectively). On the contrary, the ratio of Crs at higher PEEP to Crs at lower PEEP (Crs ratio (higher/lower)) moderately correlated with NMD and R/I ratio (rho = 0.64, P < 0.001; and rho = 0.67, P < 0.001, respectively). CONCLUSIONS: NMD of the quasi-static PV curve and R/I ratio for recruitability assessment are highly correlated. In addition, NMD and R/I ratio correlated with the Crs ratio (higher/lower). Therefore, NMD and R/I ratio could be potential indicators of recruitability that can be performed at the bedside.

Bilateral phrenic nerve block as an effective means of controlling inspiratory efforts in a COVID-19 patient.

Bilateral continuous phrenic nerve block effectively regulates refractory persistent, strong inspiratory effort in a patient with coronavirus disease (COVID-19). A 73-year-old man with acute respiratory distress syndrome (ARDS) due to COVID-19 was admitted to the intensive care unit (ICU). Use of neuromuscular blocking agents (NMBAs) was stopped due to uncontrollable strong inspiratory efforts and worsened lung injury. We performed bilateral continuous phrenic nerve block, which suppressed inspiratory efforts, resulting in lung injury improvement. A bilateral continuous phrenic nerve block is a viable alternative to control refractory strong inspiratory effort leading to lung injury in cases with prolonged NMBA use.

Successful difficult airway management with emergent venovenous extracorporeal membrane oxygenation in a patient with severe tracheal deformity: a case report.

BACKGROUND: Difficult airway management is occasionally encountered in the emergency department, and recent studies suggest that extracorporeal membrane oxygenation can be useful in these cases. CASE PRESENTATION: A 74-year-old man was transferred to our hospital due to worsening dyspnea. On arrival, it was found that he was in respiratory distress and was comatose. Arterial blood gas analysis showed severe hypercapnia and respiratory acidosis. Intubation could not be done because he had severe tracheal deformity due to cervical-thoracic kyphosis secondary to vertebral tuberculosis. Therefore, we carried out surgical tracheostomy under venovenous extracorporeal membrane oxygenation. The patient's oxygenation gradually improved, and extracorporeal membrane oxygenation was withdrawn on day 8. He was transferred to another hospital on day 46 and suffered no neurological deficits. CONCLUSION: Severe tracheal deformity can result in a difficult airway. Extracorporeal membrane oxygenation is an effective life-saving approach in cases of difficult airway management due to severe tracheal deformity.

Veno-venous extracorporeal membrane oxygenation and prone ventilation for therapeutic management of COVID-19.

BACKGROUND: The efficacy and safety of the combined use of veno-venous extracorporeal membrane oxygenation (ECMO) and prone ventilation are currently not known for coronavirus disease 2019 (COVID-19). CASE PRESENTATION: We report two cases in which the combination of veno-venous ECMO and prone ventilation for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia were successfully carried out. Both patients had developed severe respiratory failure due to SARS-CoV-2 pneumonia, thus requiring veno-venous ECMO. Prone ventilation was also administered safely. CONCLUSION: Oxygenation and lung compliance gradually improved during prone ventilation, and both patients were successfully extubated. For patients with severe SARS-CoV-2 pneumonia who require veno-venous ECMO, the use of prone ventilation could be beneficial, and should be considered.

Mechanism of central hypopnoea induced by organic phosphorus poisoning.

Whether central apnoea or hypopnoea can be induced by organophosphorus poisoning remains unknown to date. By using the acute brainstem slice method and multi-electrode array system, we established a paraoxon (a typical acetylcholinesterase inhibitor) poisoning model to investigate the time-dependent changes in respiratory burst amplitudes of the pre-Bötzinger complex (respiratory rhythm generator). We then determined whether pralidoxime or atropine, which are antidotes of paraoxon, could counteract the effects of paraoxon. Herein, we showed that paraoxon significantly decreased the respiratory burst amplitude of the pre-Bötzinger complex (p < 0.05). Moreover, pralidoxime and atropine could suppress the decrease in amplitude by paraoxon (p < 0.05). Paraoxon directly impaired the pre-Bötzinger complex, and the findings implied that this impairment caused central apnoea or hypopnoea. Pralidoxime and atropine could therapeutically attenuate the impairment. This study is the first to prove the usefulness of the multi-electrode array method for electrophysiological and toxicological studies in the mammalian brainstem.

Gasping during refractory out-of-hospital cardiac arrest is a prognostic marker for favourable neurological outcome following extracorporeal cardiopulmonary resuscitation: a retrospective study.

BACKGROUND: Gasping during cardiac arrest is associated with favourable neurological outcomes for out-of-hospital cardiac arrest. Moreover, while extracorporeal cardiopulmonary resuscitation (ECPR) performed for refractory cardiac arrest can improve outcomes, factors for favourable neurological outcomes remain unknown. This study aimed to examine whether gasping during cardiac arrest resuscitation during transport by emergency medical services (EMS) was independently associated with a favourable neurological outcome for patients who underwent ECPR. This retrospective study was based on medical records of all adult patients who underwent ECPR due to refractory cardiac arrest. The primary endpoint was neurologically intact survival at discharge. The study was undertaken at Sapporo Medical University Hospital, a tertiary care centre approved by the Ministry of Health, Labour and Welfare, located in the city of Sapporo, Japan, between January 2012 and December 2018. RESULTS: Overall, 166 patients who underwent ECPR were included. During transportation by EMS, 38 patients exhibited gasping, and 128 patients did not. Twenty patients who exhibited gasping during EMS transportation achieved a favourable neurological outcome (20/38; 52.6%); 14 patients who did not exhibit gasping achieved a favourable neurological outcome (14/128; 10.9%). Gasping during transportation by EMS was independently associated with favourable neurological outcome irrespective of the type of analysis performed (multiple logistic regression analysis, odds ratio [OR] 9.52; inverse probability of treatment weighting using propensity score, OR 9.14). CONCLUSIONS: The presence of gasping during transportation by EMS was independently associated with a favourable neurological outcome in patients who underwent ECPR. The association of gasping with a favourable neurological outcome in patients with refractory cardiac arrest suggests that ECPR may be considered in such patients.

Successful use of veno-arterial extracorporeal membrane oxygenation for septic cardiomyopathy in a patient with pre-existing chronic heart failure.

BACKGROUND: Indications for using veno-arterial extracorporeal membrane oxygenation (V-A ECMO) in sepsis cases remain unclear. CASE PRESENTATION: A 66-year-old man with pre-existing chronic heart failure developed severe pneumonia resulting in refractory septic shock. He was diagnosed with septic cardiomyopathy based on depressed left ventricular ejection fraction and a dilated left ventricle based on a transthoracic echocardiogram. We initiated V-A ECMO on day 3 because the shock did not respond to conventional therapy. The patient's hemodynamics improved, and his infection was reduced. He recovered fully and was discharged on day 107 with his cardiac function restored to its baseline. CONCLUSION: Septic cardiomyopathy is a form of reversible myocardial dysfunction. Veno-arterial extracorporeal membrane oxygenation should be considered for septic cardiomyopathy with intractable circulatory failure. Pre-existing chronic heart failure is not a contraindication for VA-ECMO.

Takotsubo cardiomyopathy developed during rewarming of accidental hypothermia with extracorporeal membrane oxygenation.

BACKGROUND: We here present the first case report of takotsubo cardiomyopathy that developed during rewarming of a patient with severe accidental hypothermia with extracorporeal membrane oxygenation. CASE: A 74-year-old woman was found unresponsive outdoors and suffered cardiopulmonary arrest during transfer to our hospital. On arrival, she was still in cardiopulmonary arrest. Veno-arterial extracorporeal membrane oxygenation was initiated for resuscitation and rewarming. After admission to the intensive care unit, her blood pressure suddenly dropped, and coronary angiography on day 2 indicated intact coronary arteries. Left ventriculography showed typical takotsubo-like dysfunction in the end-systolic phase, which led to the diagnosis of takotsubo cardiomyopathy. Left ventricular wall motion gradually improved, and echocardiography on day 6 revealed that abnormalities in the left ventricular wall motion had almost disappeared. CONCLUSION: Takotsubo cardiomyopathy might arise during rewarming of patients with severe accidental hypothermia.

The prognostic value of agonal respiration in refractory cardiac arrest: a case series of non-shockable cardiac arrest successfully resuscitated through extracorporeal cardiopulmonary resuscitation.

BACKGROUND: Agonal respiration following out-of-hospital cardiac arrest is associated with favorable neurological outcomes. Resuscitation using extracorporeal membrane oxygenation could contribute to achieving favorable neurological outcomes in patients with refractory cardiac arrest. CASE PRESENTATION: We report two cases of refractory cardiac arrest with non-shockable rhythms and agonal respiration; both patients were successfully resuscitated through extracorporeal cardiopulmonary resuscitation (ECPR). Both patients were breathing spontaneously upon arrival. One patient was asystolic and the other experienced pulseless electrical activity followed by ventricular fibrillation. Agonal respiration was observed in both and ECPR was implemented, leading to a favorable neurological outcome at discharge. CONCLUSION: The presence of agonal respiration has the potential to confer a favorable neurological outcome in patients with refractory cardiac arrest if maintained, even when the initial cardiac rhythm is not shockable. In these cases, resuscitation should not be abandoned, and ECPR should be considered.

Successful resuscitation for cardiac arrest due to severe accidental hypothermia accompanied by mandibular rigidity: a case of cold stiffening mimicking rigor mortis.

BACKGROUND: In cases of severe accidental hypothermia, it was recommended that resuscitation should be continued until the patient has rewarmed, as hypothermia itself can preserve cerebral function, and hypothermic cardiac arrest is reversible. During cardiopulmonary resuscitation for normothermic patients, muscle rigidity suggests the initiation of postmortem changes such as rigor mortis and can lead to the termination of resuscitation. Currently, the prognosis of cardiac arrest due to severe accidental hypothermia accompanied by rigidity is unknown. CASE PRESENTATION: A 29-year-old woman was found unresponsive near a snowy mountain trail. Upon discovery, she was found to be in cardiac arrest with an initial asystole rhythm and exhibited mandibular rigidity. On admission, her core temperature was 22 °C. Although cardiac arrest continued, and she showed no response to normal resuscitation, blood gas analysis revealed that her initial serum potassium level was 5.4 mmol/L. Extracorporeal membrane oxygenation (ECMO) for systemic perfusion and rewarming was initiated. After ECMO was introduced, return of spontaneous circulation was achieved. She showed no neurological impairments at discharge. CONCLUSIONS: Muscle rigidity does not rule out the possibility of resuscitation in patients with severe accidental hypothermia under cardiac arrest. Serum potassium levels may assist in deciding whether ECMO should be introduced, even if a patient is in asystole. This knowledge may help emergency physicians to save the lives of such patients.