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Valkov S, Nilsen JH, Mohyuddin R, Schanche T, Kondratiev T, Sieck GC, Tveita T. Autoregulation of Cerebral Blood Flow During 3-h Continuous Cardiopulmonary Resuscitation at 27°C. Front Physiol 2022; 13:925292. [PMID: 35755426 PMCID: PMC9218627 DOI: 10.3389/fphys.2022.925292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 05/20/2022] [Indexed: 11/13/2022] Open
Abstract
Introduction: Victims of accidental hypothermia in hypothermic cardiac arrest (HCA) may survive with favorable neurologic outcome if early and continuous prehospital cardiopulmonary resuscitation (CPR) is started and continued during evacuation and transport. The efficacy of cerebral autoregulation during hypothermic CPR is largely unknown and is aim of the present experiment. Methods: Anesthetized pigs (n = 8) were surface cooled to HCA at 27°C before 3 h continuous CPR. Central hemodynamics, cerebral O2 delivery (DO2) and uptake (VO2), cerebral blood flow (CBF), and cerebral perfusion pressure (CPP) were determined before cooling, at 32°C and at 27°C, then at 15 min after the start of CPR, and hourly thereafter. To estimate cerebral autoregulation, the static autoregulatory index (sARI), and the CBF/VO2 ratio were determined. Results: After the initial 15-min period of CPR at 27°C, cardiac output (CO) and mean arterial pressure (MAP) were reduced significantly when compared to corresponding values during spontaneous circulation at 27°C (-66.7% and -44.4%, respectively), and remained reduced during the subsequent 3-h period of CPR. During the first 2-h period of CPR at 27°C, blood flow in five different brain areas remained unchanged when compared to the level during spontaneous circulation at 27°C, but after 3 h of CPR blood flow in 2 of the 5 areas was significantly reduced. Cooling to 27°C reduced cerebral DO2 by 67.3% and VO2 by 84.4%. Cerebral VO2 was significantly reduced first after 3 h of CPR. Cerebral DO2 remained unaltered compared to corresponding levels measured during spontaneous circulation at 27°C. Cerebral autoregulation was preserved (sARI > 0.4), at least during the first 2 h of CPR. Interestingly, the CBF/VO2 ratio during spontaneous circulation at 27°C indicated the presence of an affluent cerebral DO2, whereas after CPR, the CBF/VO2 ratio returned to the level of spontaneous circulation at 38°C. Conclusion: Despite a reduced CO, continuous CPR for 3 h at 27°C provided sufficient cerebral DO2 to maintain aerobic metabolism and to preserve cerebral autoregulation during the first 2-h period of CPR. This new information supports early start and continued CPR in accidental hypothermia patients during rescue and transportation for in hospital rewarming.
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Affiliation(s)
- Sergei Valkov
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Jan Harald Nilsen
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway
| | - Rizwan Mohyuddin
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Torstein Schanche
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
| | - Timofei Kondratiev
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
| | - Torkjel Tveita
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT the Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
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2
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Gaustad SE, Kondratiev TV, Eftedal I, Tveita T. Effects of Cold Decompression on Hemodynamic Function and Decompression Sickness Risk in a Dry Diving Rat Model. Front Physiol 2021; 12:763975. [PMID: 34803743 PMCID: PMC8595113 DOI: 10.3389/fphys.2021.763975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/05/2021] [Indexed: 11/21/2022] Open
Abstract
Background: Diving in cold water is thought to increase the risk of decompression sickness (DCS), especially if the diver is cold during decompression. In this study, we investigated hemodynamic function and DCS risk in an animal model, where cold decompression was followed by rewarming at the surface. Methods: Nine female Sprague Dawley rats had pressure-volume catheters inserted into their left heart ventricle and femoral artery before they were exposed to dry air dives in which their core temperature was normothermic during the bottom phase, cold (35°C) during decompression, and normothermic after the dive. Data from an earlier study were used as controls. The rats were compressed in air to 600kPa, maintained at pressure for 45min, and decompressed at 50kPa/min. Hemodynamic data were recorded before, during, and 60min after decompression. Venous gas bubbles were recorded in the right heart ventricle and pulmonary artery for 60min after the dive. Results and Conclusion: During decompression, cardiac output (CO), and stroke volume (SV) decreased equally in cold rats and controls. CO and SV were temporarily re-established at the surface, before falling again in the cold rats. There was no difference in post-dive venous bubble grades. However, as the post-dive fall in CO and SV could be a sign of gas emboli obstructing the pulmonary circulation, we cannot conclude whether the DCS risk was increased. More sensitive bubble detection methods are needed to elucidate this point.
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Affiliation(s)
- Svein E. Gaustad
- Møreforsking AS, Volda, Norway
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Timofei V. Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Ingrid Eftedal
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
- Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
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3
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Tveita T, Sieck GC. Physiological Impact of Hypothermia: The Good, the Bad and the Ugly. Physiology (Bethesda) 2021; 37:69-87. [PMID: 34632808 DOI: 10.1152/physiol.00025.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Hypothermia is defined as a core body temperature of < 35°C, and as body temperature is reduced the impact on physiological processes can be beneficial or detrimental. The beneficial effect of hypothermia enables circulation of cooled experimental animals to be interrupted for 1-2 h without creating harmful effects, while tolerance of circulation arrest in normothermia is between 4 and 5 min. This striking difference has attracted so many investigators, experimental as well as clinical, to this field, and this discovery was fundamental for introducing therapeutic hypothermia in modern clinical medicine in the 1950's. Together with the introduction of cardiopulmonary bypass, therapeutic hypothermia has been the cornerstone in the development of modern cardiac surgery. Therapeutic hypothermia also has an undisputed role as a protective agent in organ transplantation and as a therapeutic adjuvant for cerebral protection in neonatal encephalopathy. However, the introduction of therapeutic hypothermia for organ protection during neurosurgical procedures or as a scavenger after brain and spinal trauma has been less successful. In general, the best neuroprotection seems to be obtained by avoiding hyperthermia in injured patients. Accidental hypothermia occurs when endogenous temperature control mechanisms are incapable of maintaining core body temperature within physiologic limits and core temperature becomes dependent on ambient temperature. During hypothermia spontaneous circulation is considerably reduced and with deep and/or prolonged cooling, circulatory failure may occur, which may limit safe survival of the cooled patient. Challenges that limit safe rewarming of accidental hypothermia patients include cardiac arrhythmias, uncontrolled bleeding, and "rewarming shock".
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Affiliation(s)
- Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
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4
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Mohyuddin R, Dietrichs ES, Sundaram P, Kondratiev T, Figenschou MF, Sieck GC, Tveita T. Cardiovascular Effects of Epinephrine During Experimental Hypothermia (32°C) With Spontaneous Circulation in an Intact Porcine Model. Front Physiol 2021; 12:718667. [PMID: 34552506 PMCID: PMC8450451 DOI: 10.3389/fphys.2021.718667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 06/25/2021] [Indexed: 01/05/2023] Open
Abstract
Aims: Rewarming from accidental hypothermia and therapeutic temperature management could be complicated by cardiac dysfunction. Although pharmacologic support is often applied when rewarming these patients, updated treatment recommendations are lacking. There is an underlying deficiency of clinical and experimental data to support such interventions and this prevents the development of clinical guidelines. Accordingly, we explored the clinical effects of epinephrine during hypothermic conditions. Materials and methods: Anesthetized pigs were immersion cooled to 32°C. Predetermined variables were compared at temperature/time-point baseline, after receiving 30 ng/kg/min and 90 ng/kg/min epinephrine infusions: (1) before and during hypothermia at 32°C, and after rewarming to 38°C (n = 7) and (2) a time-matched (5 h) normothermic control group (n = 5). Results: At 32°C, both stroke volume and cardiac output were elevated after 30 ng/kg/min administration, while systemic vascular resistance was reduced after 90 ng/kg/min. Epinephrine infusion did not alter blood flow in observed organs, except small intestine flow, and global O2 extraction rate was significantly reduced in response to 90 ng/kg/min infusion. Electrocardiographic measurements were unaffected by epinephrine infusion. Conclusion: Administration of both 30 ng/kg/min and 90 ng/kg/min at 32°C had a positive inotropic effect and reduced afterload. We found no evidence of increased pro-arrhythmic activity after epinephrine infusion in hypothermic pigs. Our experiment therefore suggests that β₁-receptor stimulation with epinephrine could be a favorable strategy for providing cardiovascular support in hypothermic patients, at core temperatures >32°C.
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Affiliation(s)
- Rizwan Mohyuddin
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Erik Sveberg Dietrichs
- Experimental and Clinical Pharmacology Research Group, Department of Medical Biology, UiT, The Arctic University of Norway, Tromsø, Norway.,Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway
| | - Predip Sundaram
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Timofey Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Marie Fjellanger Figenschou
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MI, United States
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5
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Nilsen JH, Schanche T, Valkov S, Mohyuddin R, Haaheim B, Kondratiev TV, Næsheim T, Sieck GC, Tveita T. Effects of rewarming with extracorporeal membrane oxygenation to restore oxygen transport and organ blood flow after hypothermic cardiac arrest in a porcine model. Sci Rep 2021; 11:18918. [PMID: 34556695 PMCID: PMC8460815 DOI: 10.1038/s41598-021-98044-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 08/26/2021] [Indexed: 02/08/2023] Open
Abstract
We recently documented that cardiopulmonary resuscitation (CPR) generates the same level of cardiac output (CO) and mean arterial pressure (MAP) during both normothermia (38 °C) and hypothermia (27 °C). Furthermore, continuous CPR at 27 °C provides O2 delivery (ḊO2) to support aerobic metabolism throughout a 3-h period. The aim of the present study was to investigate the effects of extracorporeal membrane oxygenation (ECMO) rewarming to restore ḊO2 and organ blood flow after prolonged hypothermic cardiac arrest. Eight male pigs were anesthetized and immersion cooled to 27 °C. After induction of hypothermic cardiac arrest, CPR was started and continued for a 3-h period. Thereafter, the animals were rewarmed with ECMO. Organ blood flow was measured using microspheres. After cooling with spontaneous circulation to 27 °C, MAP and CO were initially reduced to 66 and 44% of baseline, respectively. By 15 min after the onset of CPR, there was a further reduction in MAP and CO to 42 and 25% of baseline, respectively, which remained unchanged throughout the rest of 3-h CPR. During CPR, ḊO2 and O2 uptake (V̇O2) fell to critical low levels, but the simultaneous small increase in lactate and a modest reduction in pH, indicated the presence of maintained aerobic metabolism. Rewarming with ECMO restored MAP, CO, ḊO2, and blood flow to the heart and to parts of the brain, whereas flow to kidneys, stomach, liver and spleen remained significantly reduced. CPR for 3-h at 27 °C with sustained lower levels of CO and MAP maintained aerobic metabolism sufficient to support ḊO2. Rewarming with ECMO restores blood flow to the heart and brain, and creates a "shockable" cardiac rhythm. Thus, like continuous CPR, ECMO rewarming plays a crucial role in "the chain of survival" when resuscitating victims of hypothermic cardiac arrest.
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Affiliation(s)
- Jan Harald Nilsen
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway ,grid.420120.50000 0004 0481 3017Department of Research and Education, Norwegian Air Ambulance Foundation, 1441 Drøbak, Norway ,grid.412244.50000 0004 4689 5540Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038 Tromsø, Norway
| | - Torstein Schanche
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway ,grid.66875.3a0000 0004 0459 167XDepartment of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN USA
| | - Sergei Valkov
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Rizwan Mohyuddin
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Brage Haaheim
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Timofei V. Kondratiev
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Torvind Næsheim
- grid.412244.50000 0004 4689 5540Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038 Tromsø, Norway
| | - Gary C. Sieck
- grid.66875.3a0000 0004 0459 167XDepartment of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN USA
| | - Torkjel Tveita
- grid.10919.300000000122595234Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, 9037 Tromsø, Norway ,grid.412244.50000 0004 4689 5540Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038 Tromsø, Norway ,grid.66875.3a0000 0004 0459 167XDepartment of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN USA
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6
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Selli AL, Kuzmiszyn AK, Smaglyukova N, Kondratiev TV, Fuskevåg OM, Lyså RA, Ravna AW, Tveita T, Sager G, Dietrichs ES. Treatment of Cardiovascular Dysfunction With PDE5-Inhibitors - Temperature Dependent Effects on Transport and Metabolism of cAMP and cGMP. Front Physiol 2021; 12:695779. [PMID: 34393818 PMCID: PMC8361756 DOI: 10.3389/fphys.2021.695779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/09/2021] [Indexed: 01/24/2023] Open
Abstract
Introduction Cardiovascular dysfunction is a potentially lethal complication of hypothermia. Due to a knowledge gap, pharmacological interventions are not recommended at core temperatures below 30°C. Yet, further cooling is induced in surgical procedures and survival of accidental hypothermia is reported after rewarming from below 15°C, advocating a need for evidence-based treatment guidelines. In vivo studies have proposed vasodilation and afterload reduction through arteriole smooth muscle cGMP-elevation as a favorable strategy to prevent cardiovascular dysfunction in hypothermia. Further development of treatment guidelines demand information about temperature-dependent changes in pharmacological effects of clinically relevant vasodilators. Materials and Methods Human phosphodiesterase-enzymes and inverted erythrocytes were utilized to evaluate how vasodilators sildenafil and vardenafil affected cellular efflux and enzymatic breakdown of cAMP and cGMP, at 37°C, 34°C, 32°C, 28°C, 24°C, and 20°C. The ability of both drugs to reach their cytosolic site of action was assessed at the same temperatures. IC50- and Ki-values were calculated from dose–response curves at all temperatures, to evaluate temperature-dependent effects of both drugs. Results Both drugs were able to reach the intracellular space at all hypothermic temperatures, with no reduction compared to normothermia. Sildenafil IC50 and Ki-values increased during hypothermia for enzymatic breakdown of both cAMP (IC50: 122 ± 18.9 μM at 37°C vs. 269 ± 14.7 μM at 20°C, p < 0.05) and cGMP (IC50: 0.009 ± 0.000 μM at 37°C vs. 0.024 ± 0.004 μM at 32°C, p < 0.05), while no significant changes were detected for vardenafil. Neither of the drugs showed significant hypothermia-induced changes in IC50 and Ki–values for inhibition of cellular cAMP and cGMP efflux. Conclusion Sildenafil and particularly vardenafil were ableto inhibit elimination of cGMP down to 20°C. As the cellular effects of these drugs can cause afterload reduction, they show potential in treating cardiovascular dysfunction during hypothermia. As in normothermia, both drugs showed higher selectivity for inhibition of cGMP-elimination than cAMP-elimination at low core temperatures, indicating that risk for cardiotoxic side effects is not increased by hypothermia.
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Affiliation(s)
- Anders L Selli
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Adrina K Kuzmiszyn
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Natalia Smaglyukova
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Timofei V Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Ole-Martin Fuskevåg
- Department of Laboratory Medicine, Division of Diagnostic Services, University Hospital of North Norway, Tromsø, Norway
| | - Roy A Lyså
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Aina W Ravna
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Torkjel Tveita
- Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Georg Sager
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway
| | - Erik S Dietrichs
- Experimental and Clinical Pharmacology, Department of Medical Biology, UiT - The Arctic University of Norway, Tromsø, Norway.,Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway
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7
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Nilsen JH, Schanche T, Kondratiev TV, Hevrøy O, Sieck GC, Tveita T. Maintaining intravenous volume mitigates hypothermia-induced myocardial dysfunction and accumulation of intracellular Ca 2. Exp Physiol 2021; 106:1196-1207. [PMID: 33728692 DOI: 10.1113/ep089397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/11/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Detailed guidelines for volume replacement to counteract hypothermia-induced intravascular fluid loss are lacking. Evidence suggests colloids might have beneficial effects compared to crystalloids. Are central haemodynamic function and level of hypothermia-induced calcium overload, as a marker of cardiac injury, restored by fluid substitution during rewarming, and are colloids favourable to crystalloids? What is the main finding and its importance? Infusion with crystalloid or dextran during rewarming abolished post-hypothermic cardiac dysfunction, and partially mitigated myocardial calcium overload. The effects of volume replacement to support haemodynamic function are comparable to those using potent cardio-active drugs. These findings underline the importance of applying intravascular volume replacement to maintain euvolaemia during rewarming. ABSTRACT Previous research exploring pathophysiological mechanisms underlying circulatory collapse after rewarming victims of severe accidental hypothermia has documented post-hypothermic cardiac dysfunction and hypothermia-induced elevation of intracellular Ca2+ concentration ([Ca2+ ]i ) in myocardial cells. The aim of the present study was to examine if maintaining euvolaemia during rewarming mitigates cardiac dysfunction and/or normalizes elevated myocardial [Ca2+ ]i . A total of 21 male Wistar rats (300 g) were surface cooled to 15°C, then maintained at 15°C for 4 h, and subsequently rewarmed to 37°C. The rats were randomly assigned to one of three groups: (1) non-intervention control (n = 7), (2) dextran treated (i.v. 12 ml/kg dextran 70; n = 7), or (3) crystalloid treated (24 ml/kg 0.9% i.v. saline; n = 7). Infusions occurred during the first 30 min of rewarming. Arterial blood pressure, stroke volume (SV), cardiac output (CO), contractility (dP/dtmax ) and blood gas changes were measured. Post-hypothermic changes in [Ca2+ ]i were measured using the method of radiolabelled Ca2+ (45 Ca2+ ). Untreated controls displayed post-hypothermic cardiac dysfunction with significantly reduced CO, SV and dP/dtmax . In contrast, rats receiving crystalloid or dextran treatment showed a return to pre-hypothermic control levels of CO and SV after rewarming, with the dextran group displaying significantly better amelioration of post-hypothermic cardiac dysfunction than the crystalloid group. Compared to the post-hypothermic increase in myocardial [Ca2+ ]i in non-treated controls, [Ca2+ ]i values with crystalloid and dextran did not increase to the same extent after rewarming. Volume replacement with crystalloid or dextran during rewarming abolishes post-hypothermic cardiac dysfunction, and partially mitigates the hypothermia-induced elevation of [Ca2+ ]i .
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Affiliation(s)
- Jan Harald Nilsen
- Anesthesia and Critical Care research group, Department of Clinical Medicine, UiT, Arctic University of Norway, Tromsø, Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Torstein Schanche
- Anesthesia and Critical Care research group, Department of Clinical Medicine, UiT, Arctic University of Norway, Tromsø, Norway.,Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Timofei V Kondratiev
- Anesthesia and Critical Care research group, Department of Clinical Medicine, UiT, Arctic University of Norway, Tromsø, Norway
| | - Olav Hevrøy
- Department of Anesthesiology and Intensive Care, Haukeland University Hospital, Bergen, Norway
| | - Gary C Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Torkjel Tveita
- Anesthesia and Critical Care research group, Department of Clinical Medicine, UiT, Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway.,Department of Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
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8
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Håheim B, Kondratiev T, Dietrichs ES, Tveita T. Comparison Between Two Pharmacologic Strategies to Alleviate Rewarming Shock: Vasodilation vs. Inodilation. Front Med (Lausanne) 2020; 7:566388. [PMID: 33282886 PMCID: PMC7689197 DOI: 10.3389/fmed.2020.566388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 10/05/2020] [Indexed: 11/13/2022] Open
Abstract
Rewarming from hypothermia is often challenged by coexisting cardiac dysfunction, depressed organ blood flow (OBF), and increased systemic vascular resistance. Previous research shows cardiovascular inotropic support and vasodilation during rewarming to elevate cardiac output (CO). The present study aims to compare the effects of inodilatation by levosimendan (LS) and vasodilation by nitroprusside (SNP) on OBF and global oxygen transport during rewarming from hypothermia. We used an in vivo experimental rat model of 4 h 15°C hypothermia and rewarming. A stable isotope-labeled microsphere technique was used to determine OBF. Cardiac and arterial pressures were monitored with fluid-filled pressure catheters, and CO was measured by thermodilution. Two groups were treated with either LS (n = 7) or SNP (n = 7) during the last hour of hypothermia and throughout rewarming. Two groups served as hypothermic (n = 7) and normothermic (n = 6) controls. All hypothermia groups had significantly reduced CO, oxygen delivery, and OBF after rewarming compared to their baseline values. After rewarming, LS had elevated CO significantly more than SNP (66.57 ± 5.6/+30% vs. 54.48 ± 5.2/+14%) compared to the control group (47.22 ± 3.9), but their ability to cause elevation of brain blood flow (BBF) was the same (0.554 ± 0.180/+81 vs. 0.535 ± 0.208/+75%) compared to the control group (0.305 ± 0.101). We interpret the vasodilator properties of LS and SNP to be the primary source to increase organ blood flow, superior to the increase in CO.
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Affiliation(s)
- Brage Håheim
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Timofei Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Erik Sveberg Dietrichs
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway.,Experimental and Clinical Pharmacology Research Group, Department of Medical Biology, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
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9
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Nilsen JH, Valkov S, Mohyuddin R, Schanche T, Kondratiev TV, Naesheim T, Sieck GC, Tveita T. Study of the Effects of 3 h of Continuous Cardiopulmonary Resuscitation at 27°C on Global Oxygen Transport and Organ Blood Flow. Front Physiol 2020; 11:213. [PMID: 32372965 PMCID: PMC7177004 DOI: 10.3389/fphys.2020.00213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 02/24/2020] [Indexed: 12/19/2022] Open
Abstract
Aims Complete restitution of neurologic function after 6 h of pre-hospital resuscitation and in-hospital rewarming has been reported in accidental hypothermia patients with cardiac arrest (CA). However, the level of restitution of circulatory function during long-lasting hypothermic cardiopulmonary resuscitation (CPR) remains largely unknown. We compared the effects of CPR in replacing spontaneous circulation during 3 h at 27°C vs. 45 min at normothermia by determining hemodynamics, global oxygen transport (DO2), oxygen uptake (VO2), and organ blood flow. Methods Anesthetized pigs (n = 7) were immersion cooled to CA at 27°C. Predetermined variables were compared: (1) Before cooling, during cooling to 27°C with spontaneous circulation, after CA and subsequent continuous CPR (n = 7), vs. (2) before CA and during 45 min CPR in normothermic pigs (n = 4). Results When compared to corresponding values during spontaneous circulation at 38°C: (1) After 15 min of CPR at 27°C, cardiac output (CO) was reduced by 74%, mean arterial pressure (MAP) by 63%, DO2 by 47%, but organ blood flow was unaltered. Continuous CPR for 3 h maintained these variables largely unaltered except for significant reduction in blood flow to the heart and brain after 3 h, to the kidneys after 1 h, to the liver after 2 h, and to the stomach and small intestine after 3 h. (2) After normothermic CPR for 15 min, CO was reduced by 71%, MAP by 54%, and DO2 by 63%. After 45 min, hemodynamic function had deteriorated significantly, organ blood flow was undetectable, serum lactate increased by a factor of 12, and mixed venous O2 content was reduced to 18%. Conclusion The level to which CPR can replace CO and MAP during spontaneous circulation at normothermia was not affected by reduction in core temperature in our setting. Compared to spontaneous circulation at normothermia, 3 h of continuous resuscitation at 27°C provided limited but sufficient O2 delivery to maintain aerobic metabolism. This fundamental new knowledge is important in that it encourages early and continuous CPR in accidental hypothermia victims during evacuation and transport.
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Affiliation(s)
- Jan Harald Nilsen
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway
| | - Sergei Valkov
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Rizwan Mohyuddin
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Torstein Schanche
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Timofei V Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Torvind Naesheim
- Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
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10
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Dow J, Giesbrecht GG, Danzl DF, Brugger H, Sagalyn EB, Walpoth B, Auerbach PS, McIntosh SE, Némethy M, McDevitt M, Schoene RB, Rodway GW, Hackett PH, Zafren K, Bennett BL, Grissom CK. Wilderness Medical Society Clinical Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update. Wilderness Environ Med 2019; 30:S47-S69. [PMID: 31740369 DOI: 10.1016/j.wem.2019.10.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 10/03/2019] [Accepted: 10/09/2019] [Indexed: 01/16/2023]
Abstract
To provide guidance to clinicians, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and a balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is the 2019 update of the Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2014 Update.
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Affiliation(s)
- Jennifer Dow
- Alaska Regional Hospital Anchorage, Anchorage, AK; National Park Service: Alaska Region, Anchorage, AK.
| | - Gordon G Giesbrecht
- Faculty of Kinesiology and Recreation Management, Departments of Anesthesia and Emergency Medicine, University of Manitoba, Winnipeg, Canada
| | - Daniel F Danzl
- Department of Emergency Medicine, University of Louisville, School of Medicine, Louisville, KY
| | - Hermann Brugger
- International Commission for Mountain Emergency Medicine (ICAR MEDCOM), Bolzano, Italy; Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
| | | | - Beat Walpoth
- Service of Cardiovascular Surgery, University Hospital of Geneva, Geneva, Switzerland
| | - Paul S Auerbach
- Departments of Emergency Medicine and Surgery, Stanford University School of Medicine, Stanford, CA
| | - Scott E McIntosh
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT
| | | | | | | | - George W Rodway
- School of Nursing, University of California, Davis, Sacramento, CA
| | - Peter H Hackett
- Division of Emergency Medicine, Altitude Research Center, University of Colorado School of Medicine, Denver, CO; Institute for Altitude Medicine, Telluride, CO
| | - Ken Zafren
- International Commission for Mountain Emergency Medicine (ICAR MEDCOM), Bolzano, Italy; Departments of Emergency Medicine and Surgery, Stanford University School of Medicine, Stanford, CA
| | - Brad L Bennett
- Military & Emergency Medicine Department, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD
| | - Colin K Grissom
- Division of Pulmonary and Critical Care Medicine, Intermountain Medical Center and the University of Utah, Salt Lake City, UT
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11
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Tveita T, Arteaga GM, Han YS, Sieck GC. Cardiac troponin-I phosphorylation underlies myocardial contractile dysfunction induced by hypothermia rewarming. Am J Physiol Heart Circ Physiol 2019; 317:H726-H731. [PMID: 31373512 DOI: 10.1152/ajpheart.00101.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rewarming the intact heart after a period of hypothermia is associated with reduced myocardial contractility, decreased Ca2+ sensitivity, and increased cardiac troponin-I (cTnI) phosphorylation. We hypothesized that hypothermia/rewarming (H/R) induces left ventricular (LV) contractile dysfunction due to phosphorylation of cTnI at Ser23/24. To test this hypothesis, the response of wild-type mice (n = 7) to H/R was compared with transgenic (TG) mice expressing slow skeletal TnI (TG-ssTnI; n = 7) that lacks the Ser23/24 phosphorylation sites. Hypothermia was induced by surface cooling and maintained at 23-25°C for 3 h. Subsequently, the animals were rewarmed to 37°C. LV systolic and diastolic function was assessed using a 1.4 F pressure-volume Millar catheter introduced via the right carotid artery. At baseline conditions, there were no significant differences in LV systolic function between wild-type and TG-ssTnI mice, whereas measurements of diastolic function [isovolumic relaxation constant (τ) and end-diastolic pressure-volume relationship (EDPVR)] were significantly (P < 0.05) reduced in TG-ssTnI animals. Immediately after rewarming, significant differences between groups were found in cardiac output (CO; wild-type 6.6 ± 0.7 vs. TG-ssTnI 8.8 ± 0.7 mL/min), stroke work (SW; wild-type 796 ± 112 vs. TG-ssTnI 1208 ± 67 mmHg/μL), and the preload recruited stroke work (PRSW; wild-type 38.3 ± 4.9 vs. TG-ssTnI 68.8 ± 8.2 mmHg). However, EDPVR and τ returned to control levels within 1 h in both groups. We conclude that H/R-induced LV systolic dysfunction results from phosphorylation of cTnI at Ser23/24.NEW & NOTEWORTHY Rewarming following a period of accidental hypothermia leads to a form of acute cardiac failure (rewarming shock), which is in part due to reduced sensitivity to Ca2+ activation of myocardial contraction. The results of the present study support the hypothesis that rewarming shock is due to phosphorylation of cardiac troponin I.
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Affiliation(s)
- Torkjel Tveita
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota.,Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, The Arctic University of Norway, Tromsø, Norway
| | - Grace M Arteaga
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Young-Soo Han
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
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12
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Schanche T, Kondratiev T, Tveita T. Extracorporeal rewarming from experimental hypothermia: Effects of hydroxyethyl starch versus saline priming on fluid balance and blood flow distribution. Exp Physiol 2019; 104:1353-1362. [PMID: 31219201 DOI: 10.1113/ep087786] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/18/2019] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Mortality in accidental hypothermia patients rewarmed by extracorporeal circulation remains high. Knowledge concerning optimal fluid additions for extracorporeal rewarming is lacking, with no apparent consensus. Does colloid versus crystalloid priming have different effects on fluid balance and blood flow distribution during extracorporeal rewarming? What is the main finding and its importance? In our rat model of extracorporeal rewarming from hypothermic cardiac arrest, hydroxyethyl starch generates less tissue oedema and increases circulating blood volume and organ blood flow, compared with saline. The composition of fluid additions appears to be important during extracorporeal rewarming from hypothermia. ABSTRACT Rewarming by extracorporeal circulation (ECC) is the recommended treatment for accidental hypothermia patients with cardiac instability. Hypothermia, along with initiation of ECC, introduces major changes in fluid homeostasis and blood flow. Scientific data to recommend best practice use of ECC for rewarming these patients is lacking, and no current guidelines exist concerning the choice of priming fluid for the extracorporeal circuit. The primary aim of this study was to compare the effects of different fluid protocols on fluid balance and blood flow distribution during rewarming from deep hypothermic cardiac arrest. Sixteen anaesthetized rats were cooled to deep hypothermic cardiac arrest and rewarmed by ECC. During cooling, rats were equally randomized into two groups: an extracorporeal circuit primed with saline or primed with hydroxyethyl starch (HES). Calculations of plasma volume (PV), circulating blood volume (CBV), organ blood flow, total tissue water content, global O2 delivery and consumption were made. During and after rewarming, the pump flow rate, mean arterial pressure, PV and CBV were significantly higher in HES-treated compared with saline-treated rats. After rewarming, the HES group had significantly increased global O2 delivery and blood flow to the brain and kidneys compared with the saline group. Rats in the saline group demonstrated a significantly higher total tissue water content in the kidneys, skeletal muscle and lung. Compared with crystalloid priming, the use of an iso-oncotic colloid prime generates less tissue oedema and increases PV, CBV and organ blood flow during ECC rewarming. The composition of fluid additions appears to be an important factor during ECC rewarming from hypothermia.
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Affiliation(s)
- Torstein Schanche
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Timofei Kondratiev
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway
| | - Torkjel Tveita
- Anaesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, Tromsø, Norway
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13
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Valkov S, Mohyuddin R, Nilsen JH, Schanche T, Kondratiev TV, Sieck GC, Tveita T. Organ blood flow and O 2 transport during hypothermia (27°C) and rewarming in a pig model. Exp Physiol 2018; 104:50-60. [PMID: 30375081 DOI: 10.1113/ep087205] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 10/25/2018] [Indexed: 01/10/2023]
Abstract
NEW FINDINGS What is the central question of this study? Absence of hypothermia-induced cardiac arrest is a strong predictor for a favourable outcome after rewarming. Nevertheless, detailed knowledge of preferences in organ blood flow during rewarming with spontaneous circulation is largely unknown. What is the main finding and its importance? In a porcine model of accidental hypothermia, we find, despite a significantly reduced cardiac output during rewarming, normal blood flow and O2 supply in vital organs owing to patency of adequate physiological compensatory responses. In critical care medicine, active rewarming must aim at supporting the spontaneous circulation and maintaining spontaneous autonomous vascular control. ABSTRACT The absence of hypothermia-induced cardiac arrest is one of the strongest predictors for a favourable outcome after rewarming from accidental hypothermia. We studied temperature-dependent changes in organ blood flow and O2 delivery ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> ) in a porcine model with spontaneous circulation during 3 h of hypothermia at 27°C followed by rewarming. Anaesthetized pigs (n = 16, weighing 20-29 kg) were randomly assigned to one of two groups: (i) hypothermia/rewarming (n = 10), immersion cooled to 27°C and maintained for 3 h before being rewarmed by pleural lavage; and (ii) time-matched normothermic (38°C) control animals (n = 6), immersed for 6.5 h, the last 2 h with pleural lavage. Regional blood flow was measured using a neutron-labelled microsphere technique. Simultaneous measurements of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> and O2 consumption ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> ) were made. During hypothermia, there was a reduction in organ blood flow, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> . After rewarming, there was a 40% reduction in stroke volume and cardiac output, causing a global reduction in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> ; nevertheless, blood flow to the brain, heart, stomach and small intestine returned to prehypothermic values. Blood flow in the liver and kidneys was significantly reduced. Cerebral <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> returned to control values. After hypothermia and rewarming there is a significant lowering of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>D</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> owing to heart failure. However, compensatory mechanisms preserve O2 transport, blood flow and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:msub> </mml:math> in most organs. Nevertheless, these results indicate that hypothermia-induced heart failure requires therapeutic intervention.
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Affiliation(s)
- Sergei Valkov
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway
| | - Rizwan Mohyuddin
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway
| | - Jan Harald Nilsen
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, 1441, Drøbak, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038, Tromsø, Norway
| | - Torstein Schanche
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway
| | - Timofei V Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway
| | - Gary C Sieck
- Department of Physiology & Biomedical Engineering, Mayo Clinic Rochester, MN, USA
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway, 9037, Tromsø, Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038, Tromsø, Norway
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14
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Dietrichs ES, Håheim B, Kondratiev T, Traasdahl E, Tveita T. Effects of hypothermia and rewarming on cardiovascular autonomic control in vivo. J Appl Physiol (1985) 2017; 124:850-859. [PMID: 29357499 DOI: 10.1152/japplphysiol.00317.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Rewarming from accidental hypothermia is associated with cardiovascular dysfunction that complicates rewarming and contributes to a high mortality rate. We investigated autonomic cardiovascular control, as well as the separate effects of cooling, hypothermia, and rewarming on hemodynamic function, aiming to provide knowledge of the pathophysiology causing such complications in these patients. A rat model designed for circulatory studies during cooling, hypothermia (15°C), and rewarming was used. Spectral analysis of diastolic arterial pressure and heart rate allowed assessment of the autonomic nervous system. Hemodynamic variables were monitored using a conductance catheter in the left ventricle and a pressure transducer connected to the left femoral artery. Sympathetic cardiovascular control was reduced after rewarming. Stroke volume increased during cooling but decreased during stable hypothermia and did not normalize during rewarming. Despite autonomic dysfunction, total peripheral resistance increased during cooling and did not normalize after rewarming. The present data show that sympathetic cardiovascular control is reduced by hypothermia and rewarming. A simultaneous systolic dysfunction is seen in rewarmed animals, caused by reduced filling of the left ventricle and impaired contractile function, in the presence of normal diastolic function. These findings show that dysfunction of the efferent sympathetic nervous system could be instrumental in development of rewarming shock. NEW & NOTEWORTHY The present study shows impaired autonomic control of cardiovascular function after rewarming from severe hypothermia. In victims of accidental hypothermia, rewarming shock is a much feared and lethal complication. The pathophysiology causing such cardiovascular collapse appears complex. Our findings indicate that dysfunction of the autonomic nervous system is an important part of the pathophysiology. Thus the present study gives novel information, important for further development of treatment strategies in this patient group.
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Affiliation(s)
- Erik Sveberg Dietrichs
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway , Tromsø , Norway.,Department of Research and Education, Norwegian Air Ambulance Foundation, Drøbak, Norway.,Department of Clinical Pharmacology, Division of Diagnostic Services, University Hospital of North Norway , Tromsø , Norway
| | - Brage Håheim
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway , Tromsø , Norway
| | - Timofei Kondratiev
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway , Tromsø , Norway
| | - Erik Traasdahl
- PET Imaging Center, Division of Diagnostic Services, University Hospital of North Norway , Tromsø , Norway
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Department of Clinical Medicine, UiT, The Arctic University of Norway , Tromsø , Norway.,Division of Surgical Medicine and Intensive Care, University Hospital of North Norway , Tromsø , Norway
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15
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Abstract
Accidental hypothermia is an unintentional drop in core temperature to 35°C or below. Core temperature is best measured by esophageal probe. If core temperature cannot be measured, the degree should be estimated using clinical signs. Treatment is to protect from further heat loss, minimize afterdrop, and prevent cardiovascular collapse during rescue and resuscitation. The patient should be handled gently, kept horizontal, insulated, and actively rewarmed. Active rewarming is also beneficial in mild hypothermia but passive rewarming usually suffices. Cardiopulmonary resuscitation should be performed if there are no contraindications to resuscitation. CPR may be delayed or intermittent.
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Affiliation(s)
- Ken Zafren
- Alaska Department of Health and Social Services, State of Alaska, Juneau, AK, USA; International Commission for Mountain Emergency Medicine (ICAR MEDCOM), Zürich, Switzerland; Department of Emergency Medicine, Stanford University Medical Center, Stanford, CA, USA; Alaska Native Medical Center, Anchorage, AK, USA.
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16
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Zafren K, Giesbrecht GG, Danzl DF, Brugger H, Sagalyn EB, Walpoth B, Weiss EA, Auerbach PS, McIntosh SE, Némethy M, McDevitt M, Dow J, Schoene RB, Rodway GW, Hackett PH, Bennett BL, Grissom CK. Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia: 2014 update. Wilderness Environ Med 2015; 25:S66-85. [PMID: 25498264 DOI: 10.1016/j.wem.2014.10.010] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is an updated version of the original Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia published in Wilderness & Environmental Medicine 2014;25(4):425-445.
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Affiliation(s)
- Ken Zafren
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA; International Commission for Mountain Emergency Medicine (ICAR MEDCOM) (Dr Zafren).
| | - Gordon G Giesbrecht
- Faculty of Kinesiology and Recreation Management, Departments of Anesthesia and Emergency Medicine, University of Manitoba, Winnipeg, Canada (Dr Giesbrecht)
| | - Daniel F Danzl
- Department of Emergency Medicine, University of Louisville, School of Medicine, Louisville, KY (Dr Danzl)
| | - Hermann Brugger
- International Commission for Mountain Emergency Medicine (ICAR MEDCOM) (Dr Zafren); European Academy Institute of Mountain Emergency Medicine, Bolzano, Italy (Dr Brugger)
| | - Emily B Sagalyn
- University of Nevada School of Medicine, Reno, NV (Dr Sagalyn)
| | - Beat Walpoth
- Service of Cardiovascular Surgery, University Hospital of Geneva, Geneva, Switzerland (Dr Walpoth)
| | - Eric A Weiss
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA; Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs Weiss and Auerbach)
| | - Paul S Auerbach
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA; Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs Weiss and Auerbach)
| | - Scott E McIntosh
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Mária Némethy
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Marion McDevitt
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Jennifer Dow
- Alaska Regional Hospital, Anchorage, AK; Denali National Park and Preserve, AK (Dr Dow)
| | | | - George W Rodway
- Division of Health Sciences, University of Nevada, Reno, NV (Dr Rodway)
| | - Peter H Hackett
- Division of Emergency Medicine, Altitude Research Center, University of Colorado School of Medicine, Denver, CO; Institute for Altitude Medicine, Telluride, CO (Dr Hackett)
| | - Brad L Bennett
- Military & Emergency Medicine Department, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD (Dr Bennett)
| | - Colin K Grissom
- Division of Pulmonary and Critical Care Medicine, Intermountain Medical Center and the University of Utah, Salt Lake City, UT (Dr Grissom)
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17
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Zafren K, Giesbrecht GG, Danzl DF, Brugger H, Sagalyn EB, Walpoth B, Weiss EA, Auerbach PS, McIntosh SE, Némethy M, McDevitt M, Dow J, Schoene RB, Rodway GW, Hackett PH, Bennett BL, Grissom CK. Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia. Wilderness Environ Med 2014; 25:425-45. [PMID: 25443771 DOI: 10.1016/j.wem.2014.09.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 09/05/2014] [Accepted: 09/08/2014] [Indexed: 01/04/2023]
Abstract
To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations.
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Affiliation(s)
- Ken Zafren
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs Zafren, Weiss, and Auerbach); International Commission for Mountain Emergency Medicine (ICAR MEDCOM) (Drs Zafren and Brugger).
| | - Gordon G Giesbrecht
- Faculty of Kinesiology and Recreation Management, Departments of Anesthesia and Emergency Medicine, University of Manitoba, Winnipeg, Canada (Dr Giesbrecht)
| | - Daniel F Danzl
- Department of Emergency Medicine, University of Louisville, School of Medicine, Louisville, KY (Dr Danzl)
| | - Hermann Brugger
- International Commission for Mountain Emergency Medicine (ICAR MEDCOM) (Drs Zafren and Brugger); European Academy Institute of Mountain Emergency Medicine, Bolzano, Italy (Dr Brugger)
| | - Emily B Sagalyn
- University of Nevada School of Medicine, Reno, NV (Dr Sagalyn)
| | - Beat Walpoth
- Service of Cardiovascular Surgery, University Hospital of Geneva, Geneva, Switzerland (Dr Walpoth)
| | - Eric A Weiss
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs Zafren, Weiss, and Auerbach)
| | - Paul S Auerbach
- Division of Emergency Medicine, Department of Surgery, Stanford University School of Medicine, Stanford, CA (Drs Zafren, Weiss, and Auerbach)
| | - Scott E McIntosh
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Mária Némethy
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Marion McDevitt
- Division of Emergency Medicine, University of Utah, Salt Lake City, UT (Drs McIntosh, Némethy, and McDevitt)
| | - Jennifer Dow
- Alaska Regional Hospital, Anchorage, AK (Dr Dow); Denali National Park and Preserve, AK (Dr Dow)
| | | | - George W Rodway
- Division of Health Sciences, University of Nevada, Reno, NV (Dr Rodway)
| | - Peter H Hackett
- Division of Emergency Medicine, Altitude Research Center, University of Colorado School of Medicine, Denver, CO (Dr Hackett); Institute for Altitude Medicine, Telluride, CO (Dr Hackett)
| | - Brad L Bennett
- Military & Emergency Medicine Department, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences Bethesda, MD (Dr Bennett)
| | - Colin K Grissom
- Division of Pulmonary and Critical Care Medicine, Intermountain Medical Center and the University of Utah, Salt Lake City, UT (Dr Grissom)
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Dietrichs ES, Håheim B, Kondratiev T, Sieck GC, Tveita T. Cardiovascular effects of levosimendan during rewarming from hypothermia in rat. Cryobiology 2014; 69:402-10. [PMID: 25280932 DOI: 10.1016/j.cryobiol.2014.09.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/18/2014] [Accepted: 09/22/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND Previous research aimed at ameliorating hypothermia-induced cardiac dysfunction has shown that inotropic drugs, that stimulate the cAMP, - PKA pathway via the sarcolemmal β-receptor, have a decreased inotropic effect during hypothermia. We therefore wanted to test whether levosimendan, a calcium sensitizer and dose-dependent phosphodiesterase 3 (PDE3) inhibitor, is able to elevate stroke volume during rewarming from experimental hypothermia. METHODS A rat model designed for circulatory studies during experimental hypothermia (4h at 15°C) and rewarming was used. The following three groups were included: (1) A normothermic group receiving levosimendan, (2) a hypothermic group receiving levosimendan the last hour of stable hypothermia and during rewarming, and (3) a hypothermic placebo control group. Hemodynamic variables were monitored using a Millar conductance catheter in the left ventricle (LV), and a pressure transducer connected to the left femoral artery. In order to investigate the level of PKA stimulation by PDE3 inhibition, myocardial Ser23/24-cTnI phosphorylation was measured using Western-blot. RESULTS After rewarming, stroke volume (SV), cardiac output (CO) and preload recruitable stroke work (PRSW) were restored to within pre-hypothermic values in the levosimendan-treated animals. Compared to the placebo group after rewarming, SV, CO, PRSW, as well as levels of Ser23/24-cTnI phosphorylation, were significantly higher in the levosimendan-treated animals. CONCLUSION The present data shows that levosimendan ameliorates hypothermia-induced systolic dysfunction by elevating SV during rewarming from 15°C. Inotropic treatment during rewarming from hypothermia in the present rat model is therefore better achieved through calcium sensitizing and PDE3 inhibition, than β-receptor stimulation.
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Affiliation(s)
- Erik Sveberg Dietrichs
- Dept. of Research and Education, Norwegian Air Ambulance Foundation, 1441 Drøbak, Norway; Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, UiT, The Arctic University of Norway, 9037 Tromsø, Norway.
| | - Brage Håheim
- Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; Dept. of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
| | - Timofei Kondratiev
- Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, UiT, The Arctic University of Norway, 9037 Tromsø, Norway.
| | - Gary C Sieck
- Dept. of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA; Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, UiT, The Arctic University of Norway, 9037 Tromsø, Norway.
| | - Torkjel Tveita
- Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, UiT, The Arctic University of Norway, 9037 Tromsø, Norway; Division of Surgical Medicine and Intensive Care, University Hospital of North Norway, 9038 Tromsø, Norway.
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Hunger MS, Pfitzer G. Deep hypothermia in vivo - why is it so deleterious for the heart? Acta Physiol (Oxf) 2013; 207:434-6. [PMID: 23384424 DOI: 10.1111/apha.12050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Tveita T, Sieck GC. Effects of milrinone on left ventricular cardiac function during cooling in an intact animal model. Cryobiology 2012; 65:27-32. [DOI: 10.1016/j.cryobiol.2012.03.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 03/21/2012] [Accepted: 03/21/2012] [Indexed: 11/29/2022]
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Scaravilli V, Bonacina D, Citerio G. Rewarming: facts and myths from the systemic perspective. Crit Care 2012. [PMCID: PMC3389485 DOI: 10.1186/cc11283] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Peng W, Wang X, Gao W, Lan K. In vitro kinetics of oxygen transport in erythrocyte suspension or unmodified hemoglobin solution from human and other animals. Can J Physiol Pharmacol 2011; 89:631-7. [DOI: 10.1139/y11-061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxygen transport behavior in erythrocyte suspension or in hemoglobin solution was studied as a potential therapeutic model for the clinical treatment of blood loss, and this can also provide physiological data with which to evaluate blood substitutes. In the present project, we examined the in vitro kinetics of hemoglobin binding to and releasing oxygen, to provide detailed oxygen-flux measurements for unmodified hemoglobin solutions and erythrocyte suspensions in human, as well as other vertebrates. An in vitro method was used, based on a widely used artificial system, with the oxygen saturation level being detected in real time. Results from this study indicated that the kinetic curves of human erythrocyte suspensions and hemoglobin solutions were either S-shaped or hyperbolic, respectively. Based on these curves, the significance of T50 emerged in our investigation, where T50 is defined as the time needed for 50% hemoglobin to be saturated with oxygen, and reflects the efficiency with which hemoglobin carries oxygen. This parameter may be used to diagnose blood diseases, and could be a standard for evaluating blood substitutes. In this study, we also compared the T50 of 4 species of vertebrates, and found that it shows a distinct efficiency of oxygen binding related to species, and potentially reveals the evolutionary function of hemoglobin and its possible adaptation to the environment.
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Affiliation(s)
- Weiyan Peng
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, P.R. China
| | - Xiang Wang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, P.R. China
| | - Wei Gao
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, P.R. China
| | - Ke Lan
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400030, P.R. China
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Mowery NT, Morris JA, Jenkins JM, Ozdas A, Norris PR. Core temperature variation is associated with heart rate variability independent of cardiac index: a study of 278 trauma patients. J Crit Care 2011; 26:534.e9-534.e17. [PMID: 21376520 DOI: 10.1016/j.jcrc.2010.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 11/22/2010] [Indexed: 11/25/2022]
Abstract
PURPOSE The purpose of this study is to determine if temperature extremes are associated with reduced heart rate variability (HRV) and "cardiac uncoupling." MATERIALS AND METHODS This was a retrospective, observational cohort study performed on 278 trauma intensive care unit admissions that had continuous HR, cardiac index (CI), and core temperature data from "thermodilution" Swan-Ganz catheter. Dense (captured second-by-second) physiologic data were divided into 5-minute intervals (N = 136 133; 11 344 hours of data). Mean CI, mean temperature, and integer HR SD were computed for each interval. Critically low HRV was defined as HR SD from 0.3 to 0.6 beats per minute. Temperature extremes were defined as less than 36°C or greater than 39°C. RESULTS Low HRV and CI vary with temperature. Temperature extremes are associated with increased risk for critically low HRV (odds ratio, >1.8). Cardiac index increases with temperature until hyperthermia (>40°C). At temperature extremes, changes in CI were not explained solely by changes in HR. CONCLUSIONS The conclusions of this study are (1) temperature extremes are associated with low HRV, potentially reflecting cardiac autonomic dysfunction; (2) CI increases with temperature; and (3) HRV provides additional physiologic information unobtainable via current invasive cardiac monitoring and current vital signs.
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Affiliation(s)
- Nathan T Mowery
- Department of Surgery, Wake Forest University, Winston-Salem, NC 27157, USA.
| | - John A Morris
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tenn, USA
| | - Judith M Jenkins
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tenn, USA
| | - Asli Ozdas
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tenn, USA
| | - Patrick R Norris
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tenn, USA
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Filseth OM, How OJ, Kondratiev T, Gamst TM, Tveita T. Post-hypothermic cardiac left ventricular systolic dysfunction after rewarming in an intact pig model. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2010; 14:R211. [PMID: 21092272 PMCID: PMC3220015 DOI: 10.1186/cc9334] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 09/23/2010] [Accepted: 11/23/2010] [Indexed: 11/10/2022]
Abstract
INTRODUCTION We developed a minimally invasive, closed chest pig model with the main aim to describe hemodynamic function during surface cooling, steady state severe hypothermia (one hour at 25°C) and surface rewarming. METHODS Twelve anesthetized juvenile pigs were acutely catheterized for measurement of left ventricular (LV) pressure-volume loops (conductance catheter), cardiac output (Swan-Ganz), and for vena cava inferior occlusion. Eight animals were surface cooled to 25°C, while four animals were kept as normothermic time-matched controls. RESULTS During progressive cooling and steady state severe hypothermia (25°C) cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), maximal deceleration of pressure in the cardiac cycle (dP/dt(min)), indexes of LV contractility (preload recruitable stroke work, PRSW, and maximal acceleration of pressure in the cardiac cycle, dP/dt(max)) and LV end diastolic and systolic volumes (EDV and ESV) were significantly reduced. Systemic vascular resistance (SVR), isovolumetric relaxation time (Tau), and oxygen content in arterial and mixed venous blood increased significantly. LV end diastolic pressure (EDP) remained constant. After rewarming all the above mentioned hemodynamic variables that were depressed during 25°C remained reduced, except for CO that returned to pre-hypothermic values due to an increase in heart rate. Likewise, SVR and EDP were significantly reduced after rewarming, while Tau, EDV, ESV and blood oxygen content normalized. Serum levels of cardiac troponin T (TnT) and tumor necrosis factor-alpha (TNF-α) were significantly increased. CONCLUSIONS Progressive cooling to 25°C followed by rewarming resulted in a reduced systolic, but not diastolic left ventricular function. The post-hypothermic increase in heart rate and the reduced systemic vascular resistance are interpreted as adaptive measures by the organism to compensate for a hypothermia-induced mild left ventricular cardiac failure. A post-hypothermic increase in TnT indicates that hypothermia/rewarming may cause degradation of cardiac tissue. There were no signs of inadequate global oxygenation throughout the experiments.
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Affiliation(s)
- Ole Magnus Filseth
- Department of Anesthesiology, Institute of Clinical Medicine, University of Tromsø, N-9037 Tromsø, Norway.
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Accidental hypothermia: Rewarming treatments, complications and outcomes from one university medical centre. Resuscitation 2010; 81:1550-5. [DOI: 10.1016/j.resuscitation.2010.05.023] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 04/29/2010] [Accepted: 05/05/2010] [Indexed: 11/23/2022]
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Dietrichs ES, Lindal S, Naesheim T, Ingebrigtsen T, Tveita T. Altered brain myelin sheath morphology after rewarming in situ. Ultrastruct Pathol 2010; 34:82-9. [PMID: 20192705 DOI: 10.3109/01913120903398753] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this study cerebral ultrastructure was examined in an in vivo rat model, after rewarming from profound hypothermia (15-13 degrees C). Animals held at 37 degrees C served as controls. After rewarming, brains were examined by electron microscope. Micrographs were taken randomly, analyzed anonymously, and quantified by morphometry. Serum analysis of the stress marker S-100beta was carried out in identical groups. The most striking findings in rewarmed animals, when compared to controls, were alterations of myelin sheaths (p<.008) and elevated S-100beta (p<.0001). This indicates that cells in the central nervous system are susceptible to injury in an experimental model of accidental hypothermia and rewarming.
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Affiliation(s)
- E S Dietrichs
- Department of Anesthesiology, Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
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Kondratiev TV, Wold RM, Aasum E, Tveita T. Myocardial mechanical dysfunction and calcium overload following rewarming from experimental hypothermia in vivo. Cryobiology 2008; 56:15-21. [DOI: 10.1016/j.cryobiol.2007.09.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 09/12/2007] [Accepted: 09/19/2007] [Indexed: 11/27/2022]
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Drabek T, Fisk JA, Dixon CE, Garman RH, Stezoski J, Wisnewski SR, Wu X, Tisherman SA, Kochanek PM. Prolonged deep hypothermic circulatory arrest in rats can be achieved without cognitive deficits. Life Sci 2007; 81:543-52. [PMID: 17658556 DOI: 10.1016/j.lfs.2007.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 06/11/2007] [Accepted: 06/16/2007] [Indexed: 02/07/2023]
Abstract
Cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) enable surgical repair of cardiovascular defects. However, neurological complications can result after both CPB and DHCA. We sought to investigate if 75 min of CPB or DHCA caused motor, cognitive or histological deficits in rats. Three groups were studied: DHCA, CPB, and sham. Rats in the DHCA group were subjected to 75 min DHCA at 15 degrees C, with a total CPB duration of 75 min. Rats in the CPB group were subjected to 75 min of normothermic CPB. Shams received the same anesthesia, cannulations and infusions. Motor function was assessed using beam testing on days 3-13. Cognitive performance was evaluated using Morris water maze tasks on days 7-13. Overall Performance Category (OPC) and Neurologic Deficit Score (NDS) were assessed daily. Histological Damage Score (HDS) was assessed in survivors on day 14. Sustained deficits on beam testing were seen only in the CPB group. Rats in the CPB and DHCA groups exhibited similar cognitive performance vs. sham. There were no differences in OPC or NDS between groups. Neuronal degeneration was present only in small foci in rats after DHCA (n=4/7). However, HDS was not different in individual brain regions or viscera between DHCA or CPB vs. sham. Surprisingly, CPB, but not DHCA was associated with motor deficits vs. sham, and no cognitive deficits were seen in either group vs. sham. Future studies with longer DHCA duration will be necessary to provide targets to assess novel preservation strategies.
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Affiliation(s)
- Tomas Drabek
- Safar Center for Resuscitation Research, University of Pittsburgh, School of Medicine, Pittsburgh PA 15260, USA.
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