The ResQCPR System: An Objective and Systematic Review

The resource-limiting environment of the pre-hospital setting necessitates the continuous development of tools and interventions that maximise the capabilities of emergency medical services (EMS) municipalities. One such product developed by Zoll, the ResQCPR system, attempts to enhance the effectiveness of prehospital cardiopulmonary resuscitation (CPR). The ResQCPR system is comprised of the ResQPOD, which is an impedance threshold device (ITD), and the ResQPUMP, which is an assisted compression-decompression (ACD) device. Limited data exists regarding Zoll’s specific apparatuses as well as similar such devices. This systematic analysis comprehensively summarises a number of related studies. Their methods, limitations, results, and other aspects are outlined in the respective sections. Conclusion: This review concludes by determining that the effectiveness of the ResQPUMP, in particular (and ACD devices in general), is promising while the ResQPOD’s is uncertain. Future studies are needed to determine whether the effectiveness of the ResQPUMP markedly diminishes when used independently of the ResQPOD. This is an important feature for fire departments and other EMS municipalities because outfitting all appropriate units with both devices can be quite costly. Further studies are also needed to demonstrate reproducibility in humans (because 2 of the studies used pigs as test subjects) and with a greater amount of test subjects.

The effect of the head-up position in cardiopulmonary resuscitation – A systematic review and meta-analysis

ObjectiveThe pros and cons of the head-up position (HUP) in cardiopulmonary resuscitation (CPR) have been controversial in previous studies. This study aims to clarify the effect of HUP CPR compared to supine position (SUP) CPR.MethodThree databases were comprehensively searched (PubMed, EMBASE and the Cochrane Library) for articles published from database inception to 10 May 2021. The primary outcome was cerebral perfusion pressure (CerPP). The secondary outcomes were mean intracranial pressure (ICP), mean artery pressure (MAP), coronary artery perfusion pressure (CoPP) and the return of spontaneous circulation (ROSC) rate.ResultA total of 7 studies including 138 animals were included. We found that CerPP (SMD, 1.58; 95% CI, 0.98–2.19; p < 0.01; I2 = 51%) and ICP (SMD, -3.59; 95% CI, -5.16– -2.02; p < 0.01; I2 = 87%) were decreased significantly in the HUP group. HUP had a similar MAP (SMD, -0.54; 95% CI, -1.75–0.66; p = 0.38; I2 = 87%) and ROSC rate (RR, 0.9; 95% CI, 0.31–2.60; p = 0.84; I2 = 65%) to SUP. In addition, there was an increased CoPP trend in HUP, but the difference was not statistically significant (SMD, 0.92; 95% CI, -0.24–2.08; p = 0.12; I2 = 84%)ConclusionThe HUP 30° in active compression-decompression CPR (ACD-CPR) with an impedance threshold device (ITD) can increase CerPP by significantly lowering ICP and maintaining MAP compared to SUP, and the effect is immediate and lasts the whole CPR duration. In addition, CoPP might also be increased compared to that with SUP.

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

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; <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.

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 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

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.

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

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.

Abstract 435: Controlled Sequential Elevation of the Head and Thorax Rapidly Achieves 50% of Baseline Cerebral Perfusion Pressure During Active Compression-Decompression Cardiopulmonary Resuscitation With an Impedance Threshold Device in a Swine Model of Cardiac Arrest

Introduction: Controlled sequential elevation of the head and thorax (CSE) during active compression-decompression (ACD) CPR with an impedance threshold device (ITD) has previously resulted in sustained nearly normal cerebral perfusion pressures (CerPP) of 75 mmHg. However, the optimal speed of CSE remains unknown. It is also unknown if some CPR is needed to ‘prime the system’ prior to maximal CSE. Hypothesis: An optimized CSE will achieve 50% of baseline (50% BL) CerPP in <3 minutes from the start of CPR. Methods: Female farm pigs were intubated and anesthetized. Central vascular and intracranial access were obtained. After 8 min of untreated ventricular fibrillation, pigs were placed in a customized elevation device (CED). After 2 min of ACD+ITD CPR at the lowest CED level to prime the circulation, pigs were randomized to CSE over 1) 4-min or 2) 10-min until the CED reached its highest level. ACD ITD CPR was performed for a total of 19 minutes. Based upon initial results, two additional groups of pigs were studied: one with a CSE over 2-min after the 2 min ‘priming’ step, and the other with CSE over 24-sec without priming. The primary outcome was time in minutes to achieve 50% BL of CerPP values. Results: There were six pigs per study group (4-min, 10-min, 2-min and 24-sec). The 4-min CSE group achieved 50% BL CerPP faster (min ± SD) than the 10-min CSE group (2.53 ± 1.26 vs 5.98 ± 3.16 , p=0.04, Figure 1). The 2-min CSE group CerPP was similar to the 4-min group (2.36 ± 2.18, p=0.92). The time to 50% BL CerPP trended 4 min faster in the 2-min CSE group versus the 24-sec CSE group (6.6 ± 6.73, p=0.16), as shown in the figure. With CSE, CerPPs increased over time in all groups. All pigs were resuscitated. Conclusions: A 50% BL CerPP value was achieved in <3 minutes by combining a priming step and 2-min CSE time together with ACD+ITD CPR. This optimized approach is more advantageous than the 24-sec or 10-min elevation times.

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

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.