1
|
Rittenberger JC, Clemency BM, Monaco B, Schwob J, Murphey JT, Hostler D. Comparing Hypothermic and Thermal Neutral Conditions to Induce Metabolic Suppression. Ther Hypothermia Temp Manag 2024. [PMID: 38442224 DOI: 10.1089/ther.2023.0085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024] Open
Abstract
Suppressing metabolism in astronauts could decrease CO2 production. It is unknown whether active cooling is required to suppress metabolism in sedated patients. We hypothesized that hypothermia would have an additive effect with dexmedetomidine on suppressing metabolism. This is a randomized crossover trial of healthy subjects receiving sedation with dexmedetomidine and exposure to a cold (20°C) or thermal neutral (31°C) environment for 3 hours. We measured heart rate, blood pressure, core temperature, resting oxygen consumption (VO2), resting carbon dioxide production (VCO2), and resting energy expenditure (REE) at baseline and each hour of exposure to either environment. We also evaluated components of the Defense Automated Neurobehavioral Assessment (DANA) Brief to evaluate the effect of metabolic suppression on cognition. Six subjects completed the study. Heart rate and core temperature were lower during the cold (56 bpm) condition than the thermal neutral condition (67 bpm). VO2, VCO2, and REE decreased between baseline and the 3-hour measurement in the cold condition (Δ = 0.9 mL/min, 56.94 mL/min, 487.9 Kcal/D, respectively). DANA simple response time increased between baseline and start of recovery in both conditions (20°C 136.9 cognitive efficiency [CE] and 31°C 87.83 CE). DANA procedural reaction time increased between baseline and start of recovery in the cold condition (220.6 CE) but not in the thermal neutral condition. DANA Go/No-Go time increased between baseline and start of recovery in both conditions (20°C 222.1 CE and 31°C 122.3 CE). Sedation and cold environments are required for metabolic suppression. Subjects experienced decrements in cognitive performance in both conditions. A significant recovery period may be required after metabolic suppression before completing mission critical tasks.
Collapse
Affiliation(s)
- Jon C Rittenberger
- Guthrie Robert Packer Hospital Emergency Medicine Residency, Scranton, Pennsylvania, USA
- Department of Emergency Medicine, University of Buffalo, Buffalo, New York, USA
| | - Brian M Clemency
- Department of Emergency Medicine, University of Buffalo, Buffalo, New York, USA
- Center for Research and Education in Special Environments, University of Buffalo, Buffalo, New York, USA
| | - Brian Monaco
- Department of Emergency Medicine, University of Buffalo, Buffalo, New York, USA
- Center for Research and Education in Special Environments, University of Buffalo, Buffalo, New York, USA
| | - Jacqueline Schwob
- Center for Research and Education in Special Environments, University of Buffalo, Buffalo, New York, USA
| | - Joshua T Murphey
- Center for Research and Education in Special Environments, University of Buffalo, Buffalo, New York, USA
| | - David Hostler
- Department of Emergency Medicine, University of Buffalo, Buffalo, New York, USA
- Center for Research and Education in Special Environments, University of Buffalo, Buffalo, New York, USA
| |
Collapse
|
2
|
Flickinger KL, Weissman A, Elmer J, Coppler PJ, Guyette FX, Repine MJ, Dezfulian C, Hopkins D, Frisch A, Doshi AA, Rittenberger JC, Callaway CW. Metabolic Manipulation and Therapeutic Hypothermia. Ther Hypothermia Temp Manag 2024; 14:46-51. [PMID: 37405749 DOI: 10.1089/ther.2023.0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2023] Open
Abstract
Hypothermia has multiple physiological effects, including decreasing metabolic rate and oxygen consumption (VO2). There are few human data about the magnitude of change in VO2 with decreases in core temperature. We aimed to quantify to magnitude of reduction in resting VO2 as we reduced core temperature in lightly sedated healthy individuals. After informed consent and physical screening, we cooled participants by rapidly infusing 20 mL/kg of cold (4°C) saline intravenously and placing surface cooling pads on the torso. We attempted to suppress shivering using a 1 mcg/kg intravenous bolus of dexmedetomidine followed by titrated infusion at 1.0 to 1.5 μg/(kg·h). We measured resting metabolic rate VO2 through indirect calorimetry at baseline (37°C) and at 36°C, 35°C, 34°C, and 33°C. Nine participants had mean age 30 (standard deviation 10) years and 7 (78%) were male. Baseline VO2 was 3.36 mL/(kg·min) (interquartile range 2.98-3.76) mL/(kg·min). VO2 was associated with core temperature and declined with each degree decrease in core temperature, unless shivering occurred. Over the entire range from 37°C to 33°C, median VO2 declined 0.7 mL/(kg·min) (20.8%) in the absence of shivering. The largest average decrease in VO2 per degree Celsius was by 0.46 mL/(kg·min) (13.7%) and occurred between 37°C and 36°C in the absence of shivering. After a participant developed shivering, core body temperature did not decrease further, and VO2 increased. In lightly sedated humans, metabolic rate decreases around 5.2% for each 1°C decrease in core temperature from 37°C to 33°C. Because the largest decrease in metabolic rate occurs between 37°C and 36°C, subclinical shivering or other homeostatic reflexes may be present at lower temperatures.
Collapse
Affiliation(s)
- Katharyn L Flickinger
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Alexandra Weissman
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jonathan Elmer
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Critical Care, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Patrick J Coppler
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Francis X Guyette
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Melissa J Repine
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Cameron Dezfulian
- Department of Critical Care, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Critical Care, Baylor College of Medicine, Houston, Texas, USA
- Critical Care, Texas Children's Hospital, Houston, Texas, USA
| | - David Hopkins
- Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania, USA
| | - Adam Frisch
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Ankur A Doshi
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jon C Rittenberger
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Occupational Therapy, University of Pittsburgh School of Health and Rehabilitation Sciences, Pittsburgh, Pennsylvania, USA
- Department of Emergency Medicine, Guthrie Medical Group, Sayre, Pennsylvania, USA
| | - Clifton W Callaway
- Department of Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
3
|
Rittenberger JC, Weissman A, Flickinger KL, Guyette FX, Hopkins D, Repine MJ, Dezfulian C, Doshi AA, Elmer J, Sawyer KN, Callaway CW. Glycopyrrolate does not ameliorate hypothermia associated bradycardia in healthy individuals: A randomized crossover trial. Resuscitation 2021; 164:79-83. [PMID: 34087418 DOI: 10.1016/j.resuscitation.2021.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/14/2021] [Accepted: 05/23/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Hypothermia improves outcomes following ischemia-reperfusion injury. Shivering is common and can be mediated by agents such as dexmedetomidine. The combination of dexmedetomidine and hypothermia results in bradycardia. We hypothesized that glycopyrrolate would prevent bradycardia during dexmedetomidine-mediated hypothermia. METHODS We randomly assigned eight healthy subjects to premedication with a single 0.4 mg glycopyrrolate intravenous (IV) bolus, titrated glycopyrrolate (0.01 mg IV every 3 min as needed for heart rate <50), or no glycopyrrolate during three separate sessions of 3 h cooling. Following 1 mg/kg IV dexmedetomidine bolus, subjects received 20 ml/kg IV 4 °C saline and surface cooling (EM COOLS, Weinerdorf, Austria). We titrated dexmedetomidine infusion to suppress shivering but permit arousal to verbal stimuli. After 3 h of cooling, we allowed subjects to passively rewarm. We compared heart rate, core temperature, mean arterial blood pressure, perceived comfort and thermal sensation between groups using Kruskal-Wallis test and ANOVA. RESULTS Mean age was 27 (SD 6) years and most (N = 6, 75%) were male. Neither heart rate nor core temperature differed between the groups during maintenance of hypothermia (p > 0.05). Mean arterial blood pressure was higher in the glycopyrrolate bolus condition (p < 0.048). Thermal sensation was higher in the control condition than the glycopyrrolate bolus condition (p = 0.01). Bolus glycopyrrolate resulted in less discomfort than titrated glycopyrrolate (p = 0.04). CONCLUSIONS Glycopyrrolate did not prevent the bradycardic response to hypothermia and dexmedetomidine. Mean arterial blood pressure was higher in subjects receiving a bolus of glycopyrrolate before induction of hypothermia. Bolus glycopyrrolate was associated with less intense thermal sensation and less discomfort during cooling.
Collapse
Affiliation(s)
- Jon C Rittenberger
- Robert Packer Hospital Emergency Medicine Residency, Sayre, PA, United States; Geisinger Commonwealth School of Medicine, Scranton, PA, United States; University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States.
| | - Alexandra Weissman
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - Katharyn L Flickinger
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - Francis X Guyette
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - David Hopkins
- Geisinger Commonwealth School of Medicine, Scranton, PA, United States
| | - Melissa J Repine
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - Cameron Dezfulian
- University of Pittsburgh Department of Critical Care Medicine, Pittsburgh, PA, United States
| | - Ankur A Doshi
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - Jonathan Elmer
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States; University of Pittsburgh Department of Critical Care Medicine, Pittsburgh, PA, United States
| | - Kelly N Sawyer
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| | - Clifton W Callaway
- University of Pittsburgh Department of Emergency Medicine, Pittsburgh, PA, United States
| |
Collapse
|
4
|
Rosahl SC, Covarrubias C, Wu JH, Urquieta E. Staying Cool in Space: A Review of Therapeutic Hypothermia and Potential Application for Space Medicine. Ther Hypothermia Temp Manag 2021; 12:115-128. [PMID: 33617356 DOI: 10.1089/ther.2020.0041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Despite rigorous health screenings, medical incidents during spaceflight missions cannot be avoided. With long-duration exploration flights on the rise, the likelihood of critical medical conditions with no suitable treatment on board will increase. Therapeutic hypothermia (TH) could serve as a bridge treatment in space prolonging survival and reducing neurological damage in ischemic conditions such as stroke and cardiac arrest. We conducted a review of published studies to determine the potential and challenges of TH in space based on its physiological effects, the cooling methods available, and clinical evidence on Earth. Currently, investigators have found that application of low normothermia leads to better outcomes than mild hypothermia. Data on the impact of hypothermia on a favorable neurological outcome are inconclusive due to lack of standardized protocols across hospitals and the heterogeneity of medical conditions. Adverse effects with systemic cooling are widely reported, and could be reduced through selective brain cooling and pharmacological cooling, promising techniques that currently lack clinical evidence. We hypothesize that TH has the potential for application as supportive treatment for multiple medical conditions in space and recommend further investigation of the concept in feasibility studies.
Collapse
Affiliation(s)
- Sophie C Rosahl
- Faculty of Medicine, Ruprecht-Karls-Universität, Heidelberg, Germany
| | - Claudia Covarrubias
- School of Medicine, Universidad Anáhuac Querétaro, Santiago de Querétaro, México
| | - Jimmy H Wu
- Department of Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, USA.,Translational Research Institute for Space Health, Houston, Texas, USA
| | - Emmanuel Urquieta
- Translational Research Institute for Space Health, Houston, Texas, USA.,Department of Emergency Medicine and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, USA
| |
Collapse
|
5
|
Affiliation(s)
- Adam Blumenberg
- Department of Emergency Medicine and Toxicology, Oregon Health and Science University, Portland, Oregon, USA
- Department of Emergency Medicine, Columbia University Medical Cernter, New York, New York, USA
| |
Collapse
|
6
|
Tarahovsky YS, Khrenov MO, Kovtun AL, Zakharova NM. Comparison of natural and pharmacological hypothermia in animals: Determination of activation energy of metabolism. J Therm Biol 2020; 92:102658. [DOI: 10.1016/j.jtherbio.2020.102658] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 06/30/2020] [Accepted: 06/30/2020] [Indexed: 02/07/2023]
|
7
|
Regan MD, Flynn-Evans EE, Griko YV, Kilduff TS, Rittenberger JC, Ruskin KJ, Buck CL. Shallow metabolic depression and human spaceflight: a feasible first step. J Appl Physiol (1985) 2020; 128:637-647. [PMID: 31999524 DOI: 10.1152/japplphysiol.00725.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Synthetic torpor is an induced state of deep metabolic depression (MD) in an organism that does not naturally employ regulated and reversible MD. If applied to spaceflight crewmembers, this metabolic state may theoretically mitigate numerous biological and logistical challenges of human spaceflight. These benefits have been the focus of numerous recent articles where, invariably, they are discussed in the context of hypothetical deep MD states in which the metabolism of crewmembers is profoundly depressed relative to basal rates. However, inducing these deep MD states in humans, particularly humans aboard spacecraft, is currently impossible. Here, we discuss shallow MD as a feasible first step toward synthetic torpor during spaceflight and summarize perspectives following a recent NASA-hosted workshop. We discuss methods to safely induce shallow MD (e.g., sleep and slow wave enhancement via acoustic and photoperiod stimulation; moderate sedation via dexmedetomidine), which we define as an ~20% depression of metabolic rate relative to basal levels. We also discuss different modes of shallow MD application (e.g., habitual versus targeted, whereby shallow MD is induced routinely throughout a mission or only under certain circumstances, respectively) and different spaceflight scenarios that would benefit from its use. Finally, we propose a multistep development plan toward the application of synthetic torpor to human spaceflight, highlighting shallow MD's role. As space agencies develop missions to send humans further into space than ever before, shallow MD has the potential to confer health benefits for crewmembers, reduce demands on spacecraft capacities, and serve as a testbed for deeper MD technologies.
Collapse
Affiliation(s)
- Matthew D Regan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin
| | - Erin E Flynn-Evans
- Fatigue Countermeasures Laboratory, Human Systems Integration Division, NASA Ames Research Center, Moffett Field, California
| | - Yuri V Griko
- Countermeasure Development Laboratory, Space Biosciences Division, NASA Ames Research Center, Moffett Field, California
| | - Thomas S Kilduff
- Biosciences Division, Center for Neuroscience, SRI International, Menlo Park, California
| | - Jon C Rittenberger
- Guthrie Robert Packer Hospital Emergency Medicine Program, Geisinger Commonwealth School of Medicine, Scranton, Pennsylvania
| | - Keith J Ruskin
- Department of Anesthesia and Critical Care, University of Chicago, Chicago, Illinois
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| |
Collapse
|