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

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 cmH<sub>2</sub>O) 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; <i>P</i> = 0.02) and ICP (16 ± 3 vs. 12 ± 1 mmHg; <i>P</i> = 0.04) compared to baseline, a result that was not observed during the free breathing condition (CVP, 6 ± 2 vs. 6 ± 2 mmHg, <i>P</i> = 0.87; ICP, 15 ± 3 vs. 15 ± 4 mmHg, <i>P</i> = 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; <i>P</i> = 0.1), coincident with minimal reduction in ICP (15 ± 3 vs. 14 ± 4 mmHg; <i>P =</i>0.13). The application of inspiratory resistance breathing resulted in reductions in both ICP and CVP, likely due to intrathoracic unloading.

Reducing Intracranial Pressure by Reducing Central Venous Pressure: Assessment of potential countermeasures to spaceflight associated neuro-ocular syndrome.

2020 ◽  
Author(s):  
Alexander B. Hansen ◽  
Justin Stevan Lawley ◽  
Caroline A. Rickards ◽  
Erin J. Howden ◽  
Satyam Sarma ◽  
...  
Keyword(s):  
Intracranial Pressure ◽  
Venous Pressure ◽  
Intrathoracic Pressure ◽  
Free Breathing ◽  
Central Venous ◽  
Supine Posture ◽  
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. Due 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. Due to the coupling of central venous (CVP) and intracranial pressure, we hypothesized that both ICP and CVP will be reduced during both countermeasures. In four male participants (32±13 yrs) 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 cm.H2O) to generate negative intrathoracic pressure for five-mins, and subsequently, wore bilateral thigh cuffs at 30-mmHg for two-mins. 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 the supine posture, which was not observed during the free breathing condition (CVP, 6±2 vs 6±2 mmHg; P=0.87 and 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 a 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.

Abstract P22: An Impedance Threshold Device Combined with an Automated Active Compression Decompression CPR Device (LUCAS) Improves the Chances For Survival in Pigs in Cardiac Arrest

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Timothy R Matsuura ◽  
Scott H McKnite ◽  
Anja K Metzger ◽  
Demetris Yannopoulos ◽  
Tom P Aufderheide ◽  
...  
Keyword(s):  
Venous Blood ◽  
Blood Gases ◽  
Intrathoracic Pressure ◽  
Organ Damage ◽  
Coronary Perfusion Pressure ◽  
Spontaneous Circulation ◽  
Adverse Outcomes ◽  
Coronary Perfusion ◽  
Threshold Device ◽  
Impedance Threshold Device

Background: By lowering intrathoracic pressure during the chest recoil phase of CPR, the impedance threshold device (ITD) increases circulation and the rate of return of spontaneous circulation (ROSC). This study evaluated the ITD combined with a new automated CPR device, the US version of the LUCAS, that compresses the chest and then pulls upwards with a 3 lb force. Methods and Results: After 6 min of untreated ventricular fibrillation, anesthetized female pigs (40.0±0.7 kg) were randomized to 6 min of CPR (100 compressions/min with LUCAS and ventilation: 1.0 FiO2, tidal volume of 10ml/kg, rate 12/min) with an active (−10 cm H2O resistance) (n=12) or sham ITD (n=12), and then shocked once with 120 joules of direct current. Epinephrine (0.04 mg/kg) and more CPR and shocks were used if ROSC was not achieved. Results (in mmHg) after 6 min of CPR with an active vs. sham ITD were: coronary perfusion pressure (PP) 20.8±1.2 vs. 21.0±0.9 (p=0.94); cerebral PP 8.8±1.0 vs. 10.0±0.9 (p=0.62); and end tidal CO2 38.1±1.5 and 37.1±1.3 (p=0.61). Peak and mean carotid artery blood flow (ml/min) was 323.9±15.2 vs. 256.6±21.1 (p=0.17) and 95.3±5.4 vs. 77.0±6.0 (p=0.22) with an active vs. sham ITD, respectively. Mean endotracheal pressures (mmHg) during chest recoil with an active vs. sham ITD were −2.0±0.5 vs. −0.2±0.2 (p<0.01). Arterial and venous blood gases were similar after 6 min of CPR between groups. ROSC, the primary survival endpoint for comparing the active vs. sham ITD, was 7/12 vs. 2/12 after 1 shock (p= 0.09), 12/12 vs. 5/12 after 2 shocks (p<0.01), and 12/12 vs. 7/12 after 3 shocks (p=0.04). With up to 14 shocks, 10/12 sham animals had a ROSC. All animals with ROSC lived for 30 min. There was no evidence of pulmonary edema or organ damage on autopsy with either ITD. Conclusions: After 6 min of CPR, LUCAS and active ITD resulted in lower mean airway pressures during chest recoil versus controls but hemodynamic findings were similar. However, ROSC was significantly easier to achieve with an active ITD; with up to 3 shocks twice as many animals were resuscitated with an active ITD. This benefit is most likely explained by carotid blood flows that trended higher with the active ITD. These positive findings and lack of any adverse outcomes support the safety and efficacy of this device combination.

Breathing through an inspiratory threshold device improves stroke volume during central hypovolemia in humans

2008 ◽  
Vol 104 (5) ◽  
pp. 1402-1409 ◽  
Author(s):  
Kathy L. Ryan ◽  
William H. Cooke ◽  
Caroline A. Rickards ◽  
Keith G. Lurie ◽  
Victor A. Convertino
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Lower Body Negative Pressure ◽  
Systolic Arterial Pressure ◽  
Intrathoracic Pressure ◽  
Subsequent Increase ◽  
Arterial Blood ◽  
Threshold Device ◽  
Inspiratory Resistance

Inspiratory resistance induced by breathing through an impedance threshold device (ITD) reduces intrathoracic pressure and increases stroke volume (SV) in supine normovolemic humans. We hypothesized that breathing through an ITD would also be associated with a protection of SV and a subsequent increase in the tolerance to progressive central hypovolemia. Eight volunteers (5 men, 3 women) were instrumented to record ECG and beat-by-beat arterial pressure and SV (Finometer). Tolerance to progressive lower body negative pressure (LBNP) was assessed while subjects breathed against either 0 (sham ITD) or −7 cmH2O inspiratory resistance (active ITD); experiments were performed on separate days. Because the active ITD increased LBNP tolerance time from 2,014 ± 106 to 2,259 ± 138 s ( P = 0.006), data were analyzed (time and frequency domains) under both conditions at the time at which cardiovascular collapse occurred during the sham experiment to determine the mechanisms underlying this protective effect. At this time point, arterial blood pressure, SV, and cardiac output were higher ( P ≤ 0.005) when breathing on the active ITD rather than the sham ITD, whereas indirect indicators of autonomic activity (low- and high-frequency oscillations of the R-to-R interval) were not altered. ITD breathing did not alter the transfer function between systolic arterial pressure and R-to-R interval, indicating that integrated baroreflex sensitivity was similar between the two conditions. These data show that breathing against inspiratory resistance increases tolerance to progressive central hypovolemia by better maintaining SV, cardiac output, and arterial blood pressures via primarily mechanical rather than neural mechanisms.

Abstract 259: Controlled Sequential Elevation of the Head and Thorax Combined With Active Compression Decompression Cardiopulmonary Resuscitation and an Impedance Threshold Device Improves Neurological Survival in a Swine Model of Cardiac Arrest

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Johanna C Moore ◽  
Bayert Salverda ◽  
Michael Lick ◽  
Carolina Rojas-Salvador ◽  
Guillaume Debaty ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Survival Rates ◽  
Cerebral Performance Category ◽  
Intrathoracic Pressure ◽  
Venous Access ◽  
Circulation Rate ◽  
Swine Model ◽  
Threshold Device ◽  
Neurologically Intact ◽  
Impedance Threshold Device

Introduction: Survival rates after cardiac arrest with intact brain function remain poor and are not uniformly improved with a single intervention. A bundle of care approach to CPR that enhances cerebral and coronary circulation while simultaneously lowering intracranial pressure (ICP) provides new opportunity to improve neurological survival. Hypothesis: Active compression decompression (ACD) CPR and an impedance threshold device (ITD) to regulate intrathoracic pressure with controlled sequential elevation of the head and thorax (CSE) to lower ICP and increase cerebral and coronary (CoPP) perfusion pressures, will increase neurologically intact survival when compared to a conventional (C) CPR in the flat position in pigs. Methods: Female farm pigs were sedated, intubated, and anesthetized. Central arterial and venous access were continuously monitored. Regional brain tissue perfusion (CerO2) was also measured transcutaneously. Ventricular fibrillation was induced and untreated for 10 minutes. Pigs were randomized to 1) C-CPR flat or 2) CSE ACD+ITD CPR that included 2 min of ACD+ITD with the head and heart first elevated 10 and 8 cm, respectively, and then further elevation over 2 min to 22 and 9 cm, respectively. After 19 min of CPR, pigs were defibrillated and recovered. A veterinarian blinded to the intervention assessed cerebral performance category (CPC) at 24 hours. A neurologically intact outcome was defined as a CPC score of 1 or 2. Categorical outcomes were analyzed by Chi-Square and continuous outcomes with an unpaired student’s t-test. All p-values are unadjusted. Results: Return of spontaneous circulation rate was 8/8 (100%) with CSE and 2/8 (25%) for C-CPR (p = 0.002). For the primary outcome of neurologically intact survival, 6/8 (75%) pigs survived with CPC 1 or 2 with CSE versus 1/8 (12.5%) with C-CPR (p = 0.012). CoPP (mmHg, mean ± SD) was higher with CSE at 18 minutes (41 ± 24 vs 10 ± 5, p = 0.004). CerO2 (%, mean ± SD) and ETCO 2 (mmHg, mean ± SD) values were higher at 18 minutes with CSE (32.2 ± 8.5 vs 16.5 ± 2.1, p = 0.003, and 54.9 ± 8.6 vs 19.1 ± 7.0, p < 0.001), respectively. Conclusions: The novel bundled resuscitation approach of CSE with ACD+ITD CPR increased neurologically intact survival 6-fold versus C-CPR in a swine model of cardiac arrest.

scholarly journals Current understanding of the effects of inspiratory resistance on the interactions between systemic blood pressure, cerebral perfusion, intracranial pressure, and cerebrospinal fluid dynamics

2019 ◽  
Vol 127 (5) ◽  
pp. 1206-1214 ◽  
Author(s):  
Pawel J. Winklewski ◽  
Jacek Wolf ◽  
Marcin Gruszecki ◽  
Magdalena Wszedybyl-Winklewska ◽  
Krzysztof Narkiewicz
Keyword(s):  
Blood Pressure ◽  
Intracranial Pressure ◽  
Clinical Medicine ◽  
Respiratory Muscles ◽  
Intrathoracic Pressure ◽  
Brain Perfusion ◽  
Systemic Blood Pressure ◽  
Systemic Blood ◽  
Obstructive Sleep ◽  
Inspiratory Resistance

Negative intrathoracic pressure (nITP) is generated by the respiratory muscles during inspiration to overcome inspiratory resistance, thus enabling lung ventilation. Recently developed noninvasive techniques have made it possible to assess the effects of nITP in real time in several physiological aspects such as systemic blood pressure (BP), intracranial pressure (ICP), and cerebral blood flow (CBF). It has been shown that nITP from 0 to −20 cmH2O elevates BP and diminishes ICP, which facilitates brain perfusion. The effects of nITP from −20 to −40 cmH2O on BP, ICP, and CBF remain largely unrecognized, yet even nITP at −40 cmH2O may facilitate CBF by diminishing ICP. Importantly, nITP from −20 to −40 cmH2O has been documented in adults in commonly encountered obstructive sleep apnea, which justifies research in this area. Recent revelations about interactions between ICP and BP have opened up new fields of research in physiological regulation and the pathophysiology of common diseases, such as hypertension, brain injury, and respiratory disorders. A better understanding of these interactions may translate directly into new therapies in various fields of clinical medicine.

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

Circulation ◽  
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.

scholarly journals A Trial of an Impedance Threshold Device in Out-of-Hospital Cardiac Arrest

2011 ◽  
Vol 365 (9) ◽  
pp. 798-806 ◽  
Author(s):  
Tom P. Aufderheide ◽  
Graham Nichol ◽  
Thomas D. Rea ◽  
Siobhan P. Brown ◽  
Brian G. Leroux ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Threshold Device ◽  
Hospital Cardiac Arrest ◽  
Impedance Threshold Device

Abstract 2225: A Blinded, Randomized Controlled Evaluation Of An Impedance Threshold Device During Cardiopulmonary Resuscitation In Swine

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Timothy J Mader ◽  
Adam Kellogg ◽  
Jeremy Smith ◽  
Brett Murphy ◽  
Rachael Hynds-Decoteau ◽  
...  
Keyword(s):  
Coronary Perfusion Pressure ◽  
Spontaneous Circulation ◽  
Coronary Perfusion ◽  
Continuous Variables ◽  
Active Device ◽  
Exact Test ◽  
Threshold Device ◽  
Baseline Characteristics ◽  
Controlled Evaluation ◽  
Impedance Threshold Device

Background: An impedance threshold device (ITD) has been designed to enhance circulation during CPR. A recent study suggests that the ITD does not improve hemodynamics and that it may worsen outcomes. We sought to determine, in a blinded fashion, the effect of the ITD on coronary perfusion pressure (CPP), passive ventilation (paO2 & paCO2), and return of spontaneous circulation (ROSC), in a porcine model of prolonged ventricular fibrillation (VF). We hypothesized that, when compared to sham, the active device would have no significant impact on these variables. Methods: Thirty devices (15 active/15 sham) were purchased from the Resuscitation Outcomes Consortium. Thirty male Yorkshire swine were instrumented under anesthesia. VF was electrically induced. After 8” of untreated VF, baseline characteristics were documented and CPR was begun (chest compressions rate 100/minute and ventilations at a ratio of 30:2). The device used on a given animal (active or sham) was randomly assigned. After 3 cycles of basic CPR, a second ABG was drawn and a drug cocktail was given followed by 6 CPR cycles. We recorded CPP continuously. The first 150J rescue shock (RS) was delivered after 9 complete cycles (3 minutes) of CPR. A third ABG was drawn just prior to the first RS. ROSC was defined as systolic blood pressure >80 mmHg for >60s continuously. The randomization code was revealed once preliminary data analysis was completed. Group comparisons were assessed using descriptive statistics, Student’s t -test for continuous variables and Fisher’s Exact Test for dichotomous variables. Proportions with 95% confidence intervals were calculated for the rate of ROSC. Results: Baseline characteristics between the two groups were the same. ROSC occurred in 14/15 animals in both active and sham. The table summarizes the results (mean) by group after each event/intervention (CPP in mmHg, paO2 & paCO2 in torr). Conclusions: Use of the active device had no impact on CPP, paO2 & paCO2 or ROSC compared to sham.

Abstract 138: A Before and After Study of Active Compression Decompression Cardiopulmonary Resuscitation With the Impedance Threshold Device in a Large Urban Pre-Hospital System

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_2) ◽  
Author(s):  
Johanna C Moore ◽  
Michael Grahl ◽  
Tracy Marko ◽  
Ariel Blythe-Reske ◽  
Amber Lage ◽  
...  
Keyword(s):  
Cardiac Arrest ◽  
Cardiopulmonary Resuscitation ◽  
Response Time ◽  
First Responders ◽  
The United States ◽  
Threshold Device ◽  
Before And After ◽  
Mechanical Cpr ◽  
Impedance Threshold Device ◽  
Before And After Study

Introduction: Active Compression Decompression cardiopulmonary resuscitation with an impedance threshold device (ACD+ITD CPR) is available for use in the United States. However, little is known regarding integration of this CPR system into a large urban prehospital system with short response times, routine use of mechanical CPR and ITD, and transport of patients to cardiac arrest centers. This is an ongoing before and after study of the implementation of ACD+ITD CPR in non-traumatic cardiac arrest cases 6 months pre and post protocol change. Hypothesis: Neurologically intact rates of survival, defined by Cerebral Performance Category (CPC) score of 1 or 2, would be higher post protocol. Methods: Basic life support first responders (n = 420) and paramedics (n = 207) underwent training including didactic and hands-on sessions to learn ACD+ITD CPR. The protocol included ACD+ITD CPR initially, with the option to transition to mechanical CPR at 15 minutes. Demographics, response time, CPR duration, initial rhythm, signs of perfusion during CPR, and return of spontaneous circulation (ROSC) were recorded prospectively by first responders. Chart review was performed to determine survival to hospital admission and CPC score at discharge. Results: Training occurred October 2016 to March 2017, with protocol change on May 1, 2017. Cases from November 2016-April 2017 (n = 136) and May 2017-November 2017 (n= 103) were reviewed. Complete data were available for 128 subjects pre-protocol change (94%) and 96 subjects (94%) post. Age, gender, response time, rhythm, total CPR time, and rates of bystander CPR and witnessed arrest were similar between groups. Post protocol change, 87% (89/102) received ACD+ITD CPR with median ACD+ITD CPR time of 15 minutes (range 2-300). Pre-protocol, 6/128 (4.7%) subjects survived with CPC score 1 or 2, versus 8/96 (13.5%) subjects post (difference 8.8%, 95% CI 1%-17%). ROSC rates were similar (pre: 54/127, 42.5% post: 44/93, 47%, difference 4.8%, 95% CI -8% - 18%) Conclusions: The change in protocol was straightforward with a high rate of adherence of the system for the recommended duration of therapy. Results are suggestive of a higher rate of neurological survival with the routine use of ACD+ITD CPR in a small cardiac arrest patient population.

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