Potential negative effects of epinephrine on carotid blood flow and ETCO2 during active compression–decompression CPR utilizing an impedance threshold device

Introduction: Cardiopulmonary resuscitation with the impedance threshold device and active decompression (ITD-ACD CPR) has been shown to improve chest compression generated blood flow relative to standard chest compression. Using our high-fidelity swine model of cardiac arrest treated with prolonged mechanical chest compression (MCC) we studied the effect of different lift heights (amount of lift above the natural zero point of the sternum) during active decompression. Methods: CPR was performed on six domestic swine (~30 kg) using standard physiological monitoring. Flow was measured in the abdominal aorta, inferior vena cava (IVC), right common carotid and external jugular, and left femoral artery. Ventricular fibrillation (VF) was electrically induced. MCC were started after ten minutes of VF. Four MCC waveforms were used: Standard CPR (2”, 100 CPM), and ITD-ACD CPR (2”, 80 CPM) with 0.5”, 1.0”, and 1.5” lift past the zero point. MCC waveforms were changed every 2 min in a crossover design and delivered for 56 minutes. Data were analyzed in CPR cycles which included four epochs of CPR, one of each waveform, constituting 8 minutes of compressions. Results: Lift height had a significant (p<0.05) effect on carotid and jugular blood flow. Lift heights of 1.0 and 1.5” generated significantly more carotid blood flow in all 7 CPR cycles. A lift height of 1.5” generated significantly more jugular blood flow over all 7 CPR cycles. The interaction between duration of CPR and Jugular blood flow previously observed using this animal model was not observed. Carotid and jugular blood flow as a function of waveform and CPR cycle are shown in the figure. Conclusions: ITD-ACD CPR improved carotid and jugular blood flows, suggestive of improved cerebral perfusion. A lift height of 1.5” was required for significant improvement of jugular blood flows, while ITD-ACD CPR provided significantly better carotid blood flow than standard CPR at all lift heights.

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Abstract 2002: Dual Mechanism of Blood Flow Augmentation to the Brain using an Impedance Threshold Device in a Pediatric Model of Cardiac Arrest

Circulation ◽

10.1161/circ.116.suppl_16.ii_433 ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Carly Alexander ◽

Demetris Yannopoulos ◽

Tom Aufderheide ◽

Scott McKnite ◽

Tim Matsuura ◽

...

Keyword(s):

Blood Flow ◽

Cardiac Arrest ◽

Sham Group ◽

Intrathoracic Pressure ◽

Forward Flow ◽

Carotid Blood Flow ◽

Airway Pressures ◽

Threshold Device ◽

The Brain ◽

Impedance Threshold Device

Background: During cardiac arrest use of an impedance threshold device (ITD) increases circulation and the chances for survival. The ITD has not been systematically evaluated during conventional CPR in a pediatric animal model. We hypothesized that the ITD increases blood flow to the brain by lowering intrathoracic pressure during the CPR decompression phase thus enhancing venous return to the right heart and forward flow with the subsequent compression and maintaining or lowering diastolic intracranial pressure (ICP) thus reducing resistance to forward flow. In this manner ITD use was hypothesized to mimic the ‘gasping reflex’ during CPR. Methods: In the first study 9 female propofol anesthetized piglets (10–12 kg) were subjected to 6 min of untreated ventricular fibrillation, 6 min of conventional CPR (ventilation rate 10 bpm), then 6 min of CPR with an active ITD (resistance of −10 cm H20). A second study was similar except that a sham ITD was used in 8 piglets. Results: After 2 min of active ITD treatment, decompression phase airway pressures (surrogate for intrathoracic pressure) (mmHg) decreased from −0.5 ± 0.2 to −2.6 ± 0.5 (mean ± SEM, p < 0.001) and common carotid blood flow (mL/min) increased by 65% (59.2 ± 16.7 to 91.1± 27.9, p = 0.02). In the sham group, airway pressures were unchanged and carotid blood flow decreased from 39 ± 2.5 to 38.8 ± 4.3 (p = 0.47). ICP decreased more rapidly in time and to a greater degree in 6/9 piglets when comparing ITD use to measurements preceding its application, contributing to an increase in cerebral perfusion (CePP) (mmHg) in 5/9 active ITD piglets, while in the sham group, CePPs remained the same or decreased in 8/8 piglets (p = 0.03). Coronary perfusion pressures (CPP) (mmHg) increased in 5/9 piglets after 2 min of the active ITD and remained the same or decreased in 8/8 piglets treated with the sham device (p = 0.03). Return of spontaneous circulation was achieved with a single shock in 4/9 active ITD piglets and 1/8 sham ITD piglets (p = 0.29). Conclusions: Use of an active ITD during CPR in piglets significantly increased carotid blood flow and CPPs. The ITD also lowered ICP during the decompression phase, similar to the mechanism of the ‘last gasp’, thereby reducing resistance to forward blood flow to the brain.

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Abstract 256: Active Compression Decompression CPR With 5 Centimeters Lift and an Impedance Threshold Device Significantly Improves All Markers of Cerebral and Cardiovascular Hemodynamics and Blood Flow After 8 Minutes of Standard CPR

Circulation ◽

10.1161/circ.140.suppl_2.256 ◽

2019 ◽

Vol 140 (Suppl_2) ◽

Author(s):

Michael Lick ◽

Paul S Berger ◽

Jeff R Gould ◽

Anja Metzger

Keyword(s):

Blood Flow ◽

Cerebral Oxygenation ◽

Coronary Perfusion Pressure ◽

Cerebral Oximetry ◽

Right Atrial ◽

Coronary Perfusion ◽

Flow Measurements ◽

Threshold Device ◽

Blood Flow Measurements ◽

Impedance Threshold Device

Introduction: Active compression decompression (ACD) CPR performed along with the use of an impedance threshold device (ITD) has been shown to improve cerebral and coronary hemodynamics compared to standard CPR (SCPR). In this study, we demonstrate that ACD+ITD provides significant benefits even when initiated after 8 minutes of SCPR as measured by cerebral and cardiovascular perfusion pressures, cerebral oximetry, and blood flow as determined by neutron-activated microsphere analysis. Methods: Ventricular fibrillation was induced in 10 female Yorkshire farm pigs (40.6 ± 0.7 kg) and left untreated for 6 minutes. All animals then received 8 minutes of SCPR, followed by ACD+ITD for an additional 6 minutes. CPR was performed at a rate of 100 compressions/minute at a depth of 20% (~ 5 cm) of anteroposterior chest height. During ACD there was also an active lift component of 5cm beyond resting chest position. Microspheres were injected 4 minutes after starting SCPR and 2 minutes after starting ACD+ITD. Millar catheters were placed to measure right atrial, aortic, and intracranial pressures and NIRS was used to assess regional cerebral oxygenation. 3 minute averages obtained prior to the end of each intervention were compared with Student’s t-test and reported as mean ± SEM. Results: Mean coronary perfusion pressure and cerebral perfusion pressures were significantly improved during ACD+ITD (p<0.002, Fig 1). ACD+ITD also resulted in a 7% increase in cerebral oxygenation (47 ± 2 vs 50 ± 2%, p<0.001), a 30% increase in cerebral blood flow (0.3 ± 0.1 vs 0.4 ± 0.1ml/min/gm, p<0.004), and a 30% improvement in coronary blood flow (0.6 ± 0.1 vs. 0.9 ± 0.1ml/min/gm, p<0.004). Conclusion: This study reveals the significant benefit of ACD+ITD as measured by currently available invasive and non-invasive blood flow measurements following 8 minutes of SCPR. Initiating ACD+ITD earlier can only result in further improvement of these parameters and offer a higher likelihood of survival.

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Vital organ blood flow with the impedance threshold device

Critical Care Medicine ◽

10.1097/01.ccm.0000246013.47237.86 ◽

2006 ◽

Vol 34 (Suppl) ◽

pp. S466-S473 ◽

Cited By ~ 15

Author(s):

Tom P. Aufderheide ◽

Keith G. Lurie

Keyword(s):

Blood Flow ◽

Organ Blood Flow ◽

Vital Organ ◽

Threshold Device ◽

Impedance Threshold Device

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Abstract 437: The Relation Between Cerebral Oxygenation and Blood Flow During CPR in Swine

Circulation ◽

10.1161/circ.140.suppl_2.437 ◽

2019 ◽

Vol 140 (Suppl_2) ◽

Author(s):

Jeffrey R Gould ◽

Michael Lick ◽

Joshua W Lampe ◽

Paul S Berger ◽

Anja Metzger

Keyword(s):

Blood Flow ◽

Cardiac Arrest ◽

Cerebral Blood Flow ◽

Cerebral Oxygenation ◽

Chest Compressions ◽

Threshold Device ◽

Increased Blood Flow ◽

Domestic Swine ◽

Impedance Threshold Device ◽

Anterior Posterior

Introduction: The physiology underlying cerebral oxygenation and blood flow during resuscitation from cardiac arrest (CA) is poorly understood. This study examined the relation between cerebral oxygenation and blood flow during standard CPR (SCPR) and CPR with active decompression and lift (ACD) plus an impedance threshold device (ITD). Methods: Ventricular fibrillation (VF) was electrically induced in 15 domestic swine. Following 6 minutes of untreated VF, chest compressions were initiated at 100 cpm and 10% anterior-posterior distance. Depth increased to 20% anterior-posterior distance over a 2-min period, and was then maintained for 6 minutes (SCPR). ACD+ITD was performed for an additional 6 minutes at the same rate and depth as SCPR, but with 20% anterior-posterior distance of active lift. Microspheres were injected 2 minutes after the start of SCPR and ACD+ITD to measure blood flow. Cerebral oxygenation was measured using NIRS, and 8-sec averages collected 2 minutes following microsphere injection were used for comparison. Changes in oxygenation and blood flow that occurred in response to ACD+ITD relative to SCPR were analyzed using linear regression to predict oxygenation based on blood flow. Results: ACD+ITD increased blood flow in 13 animals and oxygenation in 12 animals relative to SCPR. Changes in cerebral oxygenation were directly proportional to changes in blood flow for 12 of 15 animals in response to ACD+ITD following SCPR. Cerebral blood flow explained 34% of the variance in cerebral oxygenation ( R 2 = 0.34, F (1, 13) = 6.7, P = 0.02). Conclusions: Changes in cerebral oxygenation during CA are associated with measured changes in cerebral blood flow, however 66% of the variance in cerebral oxygenation remains unexplained. Other physiological parameters should be considered to further understand how NIRS may provide clinically useful information during resuscitation.

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Senkung des intrakraniellen Drucks durch Senkung des zentralvenösen Drucks: Bewertung möglicher Gegenmaßnahmen zum Raumfahrt-assoziierten neuro-okulären Syndrom

Karger Kompass Ophthalmologie ◽

10.1159/000516101 ◽

2021 ◽

pp. 1-2

Author(s):

Sebastian Siebelmann

Keyword(s):

Intracranial Pressure ◽

Venous Pressure ◽

Intrathoracic Pressure ◽

Free Breathing ◽

Optic Disc Edema ◽

Threshold Device ◽

Inspiratory Resistance ◽

Minimal Reduction ◽

Clinical Conditions ◽

Impedance Threshold Device

Spaceflight-associated neuro-ocular syndrome (SANS) involves unilateral or bilateral optic disc edema, widening of the optic nerve sheath, and posterior globe flattening. Owing to posterior globe flattening, it is hypothesized that microgravity causes a disproportionate change in intracranial pressure (ICP) relative to intraocular pressure. Countermeasures capable of reducing ICP include thigh cuffs and breathing against inspiratory resistance. Owing to the coupling of central venous pressure (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32 ± 13 yr) who were previously implanted with Ommaya reservoirs for treatment of unrelated clinical conditions, ICP was measured invasively through these ports. Subjects were healthy at the time of testing. CVP was measured invasively by a peripherally inserted central catheter. Participants breathed through an impedance threshold device (ITD, −7 cmH2O) to generate negative intrathoracic pressure for 5 min, and subsequently, wore bilateral thigh cuffs inflated to 30 mmHg for 2 min. Breathing through an ITD reduced both CVP (6 ± 2 vs. 3 ± 1 mmHg; P = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; P = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, P = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, P = 0.68). Inflation of the thigh cuffs to 30 mmHg caused no meaningful reduction in CVP in all four individuals (5 ± 4 vs. 5 ± 4 mmHg; P = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; P =0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

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