Clinical pilot study of different hand positions during manual chest compressions monitored with capnography

Purpose of the study

Optimal hand position for chest compressions during cardiopulmonary resuscitation is unknown. Recent imaging studies indicate significant inter-individual anatomical variations, which might cause varying haemodynamic responses with standard chest compressions. This prospective clinical pilot study intended to assess the feasibility of utilizing capnography to optimize chest compressions and identify the optimal hand position.

Materials and methods

Intubated cardiac arrest patients treated by the physician manned ambulance between February and December 2011 monitored with continuous end-tidal CO₂ (EtCO₂) measurements were included. One minute of chest compressions at the inter-nipple line (INL) optimized using EtCO₂ feedback, was followed by four 30-s intervals with compressions at four different sites; INL, 2 cm below the INL, 2 cm below and to the left of INL and 2 cm below and to the right of INL.

Results

Thirty patients were included. At the end of each 30-s interval median (range) EtCO₂ was 3.1 kPa (0.7–8.7 kPa) at INL, 3.5 kPa (0.5–10.7) 2 cm below INL, 3.5 kPa (0.5–10.3 kPa) 2 cm below and to the left of INL, and 3.8 kPa (0.4–8.8 kPa) 2 cm below and to the right of INL (p = 0.4). The EtCO₂ difference within each subject between hand positions with maximum and minimum values varied between individuals from 0.2 to 3.4 kPa (median 0.9 kPa).

Conclusion

Monitoring and optimizing chest compressions using capnography was feasible. We could not demonstrate one superior hand position, but inter-individual differences suggest optimal hand position might vary significantly among patients.     

The impact of chest compression rates on quality of chest compressions - a manikin study

Purpose

Chest compressions are often performed at a variable rate during cardiopulmonary resuscitation (CPR). The effect of compression rate on other chest compression quality variables (compression depth, duty-cycle, leaning, performance decay over time) is unknown. This randomised controlled cross-over manikin study examined the effect of different compression rates on the other chest compression quality variables.

Methods

Twenty healthcare professionals performed 2 min of continuous compressions on an instrumented manikin at rates of 80, 100, 120, 140 and 160 min⁻¹ in a random order. An electronic metronome was used to guide compression rate. Compression data were analysed by repeated measures ANOVA and are presented as mean (SD). Non-parametric data was analysed by Friedman test.

Results

At faster compression rates there were significant improvements in the number of compressions delivered (160(2) at 80 min⁻¹ vs. 312(13) compressions at 160 min⁻¹, P < 0.001); and compression duty-cycle (43(6)% at 80 min⁻¹ vs. 50(7)% at 160 min⁻¹, P < 0.001). This was at the cost of a significant reduction in compression depth (39.5(10) mm at 80 min⁻¹ vs. 34.5(11) mm at 160 min⁻¹, P < 0.001); and earlier decay in compression quality (median decay point 120 s at 80 min⁻¹ vs. 40 s at 160 min⁻¹, P < 0.001). Additionally not all participants achieved the target rate (100% at 80 min⁻¹ vs. 70% at 160 min⁻¹). Rates above 120 min⁻¹ had the greatest impact on reducing chest compression quality.

Conclusions

For Guidelines 2005 trained rescuers, a chest compression rate of 100–120 min⁻¹ for 2 min is feasible whilst maintaining adequate chest compression quality in terms of depth, duty-cycle, leaning, and decay in compression performance. Further studies are needed to assess the impact of the Guidelines 2010 recommendation for deeper and faster chest compressions.     

Electrical and mechanical recovery of cardiac function following out-of-hospital cardiac arrest

Background

Compression pauses may be particularly harmful following the electrical recovery but prior to the mechanical recovery from cardiopulmonary arrest.

Methods and results

A convenience sample of patients with out-of-hospital cardiac arrest (OOHCA) were identified. Data were exported from defibrillators to define compression pauses, electrocardiogram rhythm, PetCO2, and the presence of palpable pulses. Pulse-check episodes were randomly assigned to a derivation set (one-third) and a validation set (two-thirds). Both an unweighted and a weighted receiver–operator curve (ROC) analysis were performed on the derivation set to identify optimal thresholds to predict ROSC using heart rate and PetCO2. A sequential decision guideline was generated to predict the presence of ROSC during compressions and confirm perfusion once compressions were stopped. The ability of this decision guideline to correctly identify pauses in which pulses were and were not palpated was then evaluated. A total of 145 patients with 349 compression pauses were included. The ROC analyses on the derivation set identified an optimal pre-pause heart rate threshold of > 40 beats min⁻¹ and an optimal PetCO2 threshold of >20 mmHg to predict ROSC. A sequential decision guideline was developed using pre-pause heart rate and PetCO2 as well as the PetCO2 pattern during compression pauses to predict and rapidly confirm ROSC. This decision guideline demonstrated excellent predictive ability to identifying compression pauses with and without palpable pulses (positive predictive value 95%, negative predictive value 99%). The mean latency period between recovery of electrical and mechanical cardiac function was 78 s (95% CI 36–120 s).

Conclusions

Heart rate and PetCO2 can predict ROSC without stopping compressions, and the PetCO2 pattern during compression pauses can rapidly confirm ROSC. Use of a sequential decision guideline using heart rate and PetCO2 may reduce unnecessary compression pauses during critical moments during recovery from cardiopulmonary arrest.     

Quality of chest compressions performed by inexperienced rescuers in simulated cardiac arrest associated with pregnancy

Objective

We aimed to compare the quality of chest compressions performed by inexperienced rescuers in different positions, notably supine and at a 30° inclined lateral position, to ascertain whether high-quality chest compression is feasible on a pregnant subject in cardiac arrest.

Subjects and methods

We performed a prospective, randomised crossover design study. Each participant performed 2-min chest compressions in two different positions on a mannequin: a supine position and a 30° left inclined lateral position. After 2 min of chest compression in one position, the participant took a rest for 10 min to minimise rescuer fatigue and then performed chest compression in the second position. Data on chest compression rate, mean chest compression depth, correct compression depth rate, correct recoil rate, and correct hand position rate were collected. To measure the angle between the rescuer's arm and the victim's chest surface, chest compressions were recorded with a video recorder. After each practice session, participants were asked to report the subjective difficulty of performing chest compressions using a visual analogue scale.

Results

All 32 participants successfully completed the study. The mean compression rate and depth were 121.0 per minute and 53.3 mm in the supine position and 118.8 per minute and 52.0 mm in the inclined lateral position, respectively (p = 0.978 and p = 0.260, respectively). Also, there were no differences in the correct compression depth rate, the correct hand position rate, or the correct recoil rate (p = 0.426, p = 0.467, and p = 0.260, respectively). However, the lowest and highest angles and the subjective difficulty of chest compression differed significantly (p < 0.001, p < 0.001, and p = 0.007, respectively).

Conclusions

Inexperienced rescuers appear to be capable of performing high-quality chest compressions in a 30° inclined lateral position on pregnant women in a simulated cardiac arrest state.     

Cardiac arrest in the catheterisation laboratory: A 5-year experience of using mechanical chest compressions to facilitate PCI during prolonged resuscitation efforts

Purpose

Lengthy resuscitations in the catheterisation laboratory carry extremely high rates of mortality because it is essentially impossible to perform effective chest compressions during percutaneous coronary intervention (PCI). The purpose of this study was to evaluate the use of a mechanical chest compression device, LUCAS™, in the catheterisation laboratory, in patients who suffered circulatory arrest requiring prolonged resuscitation.

Materials and methods

The study population was comprised of patients who arrived alive to the catheterisation laboratory and then required mechanical chest compression at some time during the angiogram, PCI or pericardiocentesis between 2004 and 2008 at the Lund University Hospital. This is a retrospective registry analysis.

Results

During the study period, a total of 3058 patients were treated with PCI for ST-elevation myocardial infarction (STEMI) of whom 118 were in cardiogenic shock and 81 required defibrillations. LUCAS™ was used in 43 patients (33 STEMI, 7 non-ST-elevation myocardial infarction (NSTEMI), 2 elective PCIs and 1 patient with tamponade). Five patients had tamponade due to myocardial rupture prior to PCI that was revealed at the start of the PCI, and all five died. Of the remaining 38 patients, 1 patient underwent a successful pericardiocentesis and 36 were treated with PCI. Eleven of these patients were discharged alive in good neurological condition.

Conclusion

The use of mechanical chest compressions in the catheterisation laboratory allows for continued PCI or pericardiocentesis despite ongoing cardiac or circulatory arrest with artificially sustained circulation. It is unlikely that few, if any, of the patients would have survived without the use of mechanical chest compressions in the catheterisation laboratory.     

Functional outcomes following an in-hospital cardiac arrest: A retrospective cohort study

Background/PurposeWhilst much is known about the survival outcomes of patients that suffer an in-hospital cardiac arrest (IHCA) in Australia very little is known about the functional outcomes of survivors. This study aimed to describe the functional outcomes of a cohort of patients that suffered an in-hospital cardiac arrest (IHCA) and survived to hospital discharge in a regional Australian hospital.MethodsThis is a single-centre retrospective observational cohort study conducted in a regional Australian hospital. All adult patients that had an IHCA in the study hospital between 1 Jan 2017 and 31 Dec 2019 and survived to hospital discharge were included in the study. Functional outcomes were reported using the Modified Rankin Scale (mRS), a six-point scale for which increasing scores represent increasing disability. Scores were assigned through a retrospective review of medical notes.ResultsOverall, 102 adult patients had an IHCA during the study period, of whom 50 survived to hospital discharge. The median age of survivors was 68 years, and a third had a shockable initial arrest rhythm. Of survivors, 47 were able to be assigned both mRS scores. At discharge, 81% of patients achieved a favourable functional outcome (mRS 0–3 or equivalent function at discharge equal to admission).ConclusionsMost survivors to hospital discharge following an IHCA have a favourable functional outcome and are discharged home. Although these results are promising, larger studies across multiple hospitals are required to further inform what is known about functional outcomes in Australian IHCA survivors.     

Excessive chest compression rate is associated with insufficient compression depth in prehospital cardiac arrest

Background and goal of study

The relationship between chest compression rate and compression depth is unknown. In order to characterise this relationship, we performed an observational study in prehospital cardiac arrest patients. We hypothesised that faster compressions are associated with decreased depth.

Materials and methods

In patients undergoing prehospital cardiopulmonary resuscitation by health care professionals, chest compression rate and depth were recorded using an accelerometer (E-series monitor-defibrillator, Zoll, USA). Compression depth was compared for rates <80/min, 80–120/min and >120/min. A difference in compression depth ≥0.5 cm was considered clinically significant. Mixed models with repeated measurements of chest compression depth and rate (level 1) nested within patients (level 2) were used with compression rate as a continuous and as a categorical predictor of depth. Results are reported as means and standard error (SE).

Results and discussion

One hundred and thirty-three consecutive patients were analysed (213,409 compressions). Of all compressions 2% were <80/min, 62% between 80 and 120/min and 36% >120/min, 36% were <4 cm deep, 45% between 4 and 5 cm, 19% >5 cm. In 77 out of 133 (58%) patients a statistically significant lower depth was observed for rates >120/min compared to rates 80–120/min, in 40 out of 133 (30%) this difference was also clinically significant. The mixed models predicted that the deepest compression (4.5 cm) occurred at a rate of 86/min, with progressively lower compression depths at higher rates. Rates >145/min would result in a depth <4 cm. Predicted compression depth for rates 80–120/min was on average 4.5 cm (SE 0.06) compared to 4.1 cm (SE 0.06) for compressions >120/min (mean difference 0.4 cm, P < 0.001). Age and sex of the patient had no additional effect on depth.

Conclusions

This study showed an association between higher compression rates and lower compression depths. Avoiding excessive compression rates may lead to more compressions of sufficient depth.     

The prevalence of chest compression leaning during in-hospital cardiopulmonary resuscitation

Objective

Successful resuscitation from cardiac arrest requires the delivery of high-quality chest compressions, encompassing parameters such as adequate rate, depth, and full recoil between compressions. The lack of compression recoil (“leaning” or “incomplete recoil”) has been shown to adversely affect hemodynamics in experimental arrest models, but the prevalence of leaning during actual resuscitation is poorly understood. We hypothesized that leaning varies across resuscitation events, possibly due to rescuer and/or patient characteristics and may worsen over time from rescuer fatigue during continuous chest compressions.

Methods

This was an observational clinical cohort study at one academic medical center. Data were collected from adult in-hospital and Emergency Department arrest events using monitor/defibrillators that record chest compression characteristics and provide real-time feedback.

Results

We analyzed 112,569 chest compressions from 108 arrest episodes from 5/2007 to 2/2009. Leaning was present in 98/108 (91%) cases; 12% of all compressions exhibited leaning. Leaning varied widely across cases: 41/108 (38%) of arrest episodes exhibited <5% leaning yet 20/108 (19%) demonstrated >20% compression leaning. When evaluating blocks of continuous compressions (>120 s), only 4/33 (12%) had an increase in leaning over time and 29/33 (88%) showed a decrease (p < 0.001).

Conclusions

Chest compression leaning was common during resuscitation care and exhibited a wide distribution, with most leaning within a subset of resuscitations. Leaning decreased over time during continuous chest compression blocks, suggesting that either leaning may not be a function of rescuer fatiguing, or that it may have been mitigated by automated feedback provided during resuscitation episodes.     

Long-term evolution after in-hospital cardiac arrest in children: Prospective multicenter multinational study

ObjectiveThe main objective was to study survival and neurologic evolution of children who suffered in-hospital pediatric cardiac arrest (CA). The secondary objective was to analyze the influence of risk factors on the long term outcome after CA.Methodsprospective, international, observational, multicentric study in 48 hospitals of 12 countries. CA in children between 1 month and 18 years were analyzed using the Utstein template. Survival and neurological state measured by Pediatric Cerebral Performance Category (PCPC) scale one year after hospital discharge was evaluated.Results502 patients with in-hospital CA were evaluated. 197 of them (39.2%) survived to hospital discharge. PCPC at hospital discharge was available in 156 of survivors (79.2%). 76.9% had good neurologic state (PCPC 1–2) and 23.1% poor PCPC values (3–6). One year after cardiac arrest we could obtain data from 144 patients (28.6%). PCPC was available in 116 patients. 88 (75.9%) had a good neurologic evaluation and 28 (24.1%) a poor one. A neurological deterioration evaluated by PCPC scale was observed in 40 patients (7.9%). One year after cardiac arrest PCPC scores compared to hospital discharge had worsen in 7 patients (6%), remained constant in 103 patients (88.8%) and had improved in 6 patients (5.2%).ConclusionSurvival one year after cardiac arrest in children after in-hospital cardiac arrest is high. Neurologic outcome of these children a year after cardiac arrest is mostly the same as after hospital discharge. The factors associated with a worst long-term neurological outcome are the etiology of arrest being a traumatic or neurologic illness, and the persistency of higher lactic acid values 24 h after ROSC. A standardised basic protocol even practicable for lower developed countries would be a first step for the new multicenter studies.     

Quality of CPR: An important effect modifier in cardiac arrest clinical outcomes and intervention effectiveness trials

ObjectivesTo determine if the quality of CPR had a significant interaction with the primary study intervention in the NIH PRIMED trial.DesignThe public access database from the NIH PRIMED trial was accessed to determine if there was an interaction between quality of CPR performance, intervention, and outcome (survival to hospital discharge with modified Rankin Score (mRS) ≤3).SettingMulti-centered prehospital care systems across North America.PatientsOf 8719 adult patients enrolled, CPR quality was electronically recorded for compression rate, depth, and fraction in 6199 (71.1%), 3750 (43.0%) and 6204 (71.2%) subjects, respectively. “Acceptable” quality CPR was defined prospectively as simultaneous provision of a compression rate of 100/min (±20%), depth of 5 cm (±20%) and fraction of >50%. Significant interaction was considered as p < 0.05.InterventionStandard CPR with an activated versus sham (inactivated) ITD.Measurements and main resultsOverall, 848 and 827 patients, respectively, in the active and sham-ITD groups had “acceptable” CPR quality performed (n = 1675). There was a significant interaction between the active and sham-ITD and compression rate, depth and fraction as well as their combinations. The strongest interaction was seen with all three parameters combined (unadjusted and adjusted interaction p-value, <0.001). For all presenting rhythms, when “acceptable” quality of CPR was performed, use of an active-ITD increased survival to hospital discharge with mRS ≤3 compared to sham (61/848 [7.2%] versus 34/827 [4.1%], respectively; p = 0.006). The opposite was true for patients that did not receive “acceptable” quality of CPR. In those patients, use of an active – ITD led to significantly worse survival to hospital discharge with mRS ≤3 compared to sham (34/1012 [3.4%] versus 62/1061 [5.8%], p = 0.007).ConclusionsThere was a statistically significant interaction between the quality of CPR provided, intervention, and survival to hospital discharge with mRS ≤3 in the NIH PRIMED trial. Quality of CPR delivered can be an underestimated effect modifier in CPR clinical trials.     

Inconsistencies in cardiac arrest reporting

Data relating to survival from in-hospital cardiac arrest are used to audit staff performance and to help to determine whether new resuscitation techniques are effective. Individual studies into outcome from cardiac arrest have defined inclusion and exclusion criteria, but no such national criteria have been published to enable constant auditing of cardiac arrests. The aim of this survey was to investigate the consistency with which in-hospital cardiac arrests are recorded throughout the United Kingdom. Such data are, almost universally, collected by Resuscitation Officers (RO). A questionnaire was sent to ROs across the UK asking them to state how they would interpret and categorise hypothetical, but nonetheless typical, clinical situations involving a cardiac arrest team being called. These included an event where the patient had regained consciousness prior to the arrival of the cardiac team and also an event where rigor mortis was already present and the resuscitation promptly abandoned upon the arrival of the cardiac arrest team. The percentage survival to discharge of adult cardiac arrests for each hospital was also requested. This identified whether inclusion or exclusion of certain clinical events may have influenced cardiac arrest survival figures for that hospital. It is clear from this study that in-hospital clinical events when a cardiac arrest team is called are audited with a great deal of inconsistency. Some events, such as a patient who has rigor mortis, are excluded as a false or inappropriate call in some hospitals and included as an unsuccessful resuscitation in others. There is a need for guidance on the inclusion and exclusion criteria for auditing of cardiac arrests so that meaningful data can be obtained from across the UK and useful conclusions drawn. The situation at present will result in data being audited that are of limited use. In the era of evidence-based medicine, it seems vital to obtain accurate cardiac arrest survival figures in order to have any hope of improving them.     

Quality management in resuscitation--towards a European cardiac arrest registry (EuReCa)

Background

Knowledge about the epidemiology of cardiac arrest in Europe is inadequate.

Aim

To describe the first attempt to build up a Common European Registry of out-of-hospital cardiac arrest, called EuReCa.

Methods

After approaching key persons in participating countries of the European Resuscitation Council, five countries or areas within countries (Belgium, Germany, Andalusia, North Holland, Sweden) agreed to participate. A standardized questionnaire including 28 items, that identified various aspects of resuscitation, was developed to explore the nature of the regional/national registries. This comprises inclusion criteria, data sources, and core data, as well as technical details of the structure of the databases.

Results

The participating registers represent a population of 35 million inhabitants in Europe. During 2008, 12,446 cardiac arrests were recorded. The structure as well as the level of complexity varied markedly between the 5 regional/national registries. The incidence of attempted resuscitation ranged between registers from 17 to 53 per 100,000 inhabitants each year whilst the number of patients admitted to hospital alive ranged from 5 to 18 per 100,000 inhabitants each year. Bystander CPR varied 3-fold from 20% to 60%.

Conclusion

Five countries agreed to participate in an attempt to build up a common European Registry for out-of-hospital cardiac arrest. These regional/national registries show a marked difference in terms of structure and complexity. A marked variation was found between countries in the number of reported resuscitation attempts, the number of patients brought to hospital alive, and the proportion that received bystander CPR. At present, we are unable to explain the reason for the variability but our first findings could be a ‘wake-up-call’ for building up a high quality registry that could provide answers to this and other key questions in relation to the management of out-of-hospital cardiac arrest.     

Increased chest compression to ventilation ratio improves delivery of CPR

OBJECTIVE: Chest compressions are interrupted during cardiopulmonary resuscitation (CPR) due to human error, for ventilation, for rhythm analysis and for rescue shocks. Earlier data suggest that the recommended 15:2 compression to ventilation (C:V) ratio results in frequent interruptions of compressions during CPR. We evaluated a protocol change from the recommended C:V ratio of 15:2-30:2 during CPR in our municipal emergency medical system. METHODS: Municipal firefighters (N=875) from a single city received didactic and practical training emphasizing the importance of continuous chest compressions and recommending a 30:2 C:V ratio. Both before and after the training, digital ECG and voice records from all first-responder cases of out-of-hospital cardiac arrest were examined off-line to quantify chest compressions. The number of chest compressions delivered and the number and duration of pauses in chest compressions were compared by t-test for the first three 1min intervals when CPR was recommended. RESULTS: More compressions were delivered during minutes 1, 2, and 3 during CPR with the 30:2 C:V ratio (78+/-29, 80+/-30, 74+/-26) than with the 15:2C:V ratio (53+/-24, 57+/-24, 51+/-26) (p<0.001). Fewer pauses for ventilation occurred during each minute with the 30:2 C:V ratio (1.7+/-1.2, 2.2+/-1.2, 1.8+/-1.0) than with the 15:2C:V ratio (3.4+/-2.6, 4.7+/-7.2, 4.0+/-2.9) (p< or =0.01). Degradation of the final ECG to asystole occurred less frequently after the protocol change (asystole pre 67.1%, post 56.8%, p<0.05). The incidence of return of spontaneous circulation was not altered following the protocol change. CONCLUSIONS: Retraining first responders to use a C:V ratio of 30:2 instead of the traditional 15:2 during out-of-hospital cardiac arrest increased the number of compressions delivered per minute and decreased the number of pauses for ventilation. These data are new as they produced persistent and quantifiable changes in practitioner behavior during actual resuscitations.     

Out-of-hospital cardiac arrest

Myocardial disease and death from cardiac arrest remain significant public health problems. Sudden death events and out-of-hospital cardiac arrests (OHCA) are encountered frequently by emergency medical services. Despite more than 30 years of research, survival rates remain extremely low. This article reviews access and presentations, demographics, OHCA outcomes, and response systems and processes in treatment of patients with arrest in this setting.     

Chest compressions may be safe in arresting patients with left ventricular assist devices (LVADs)

Introduction

The number of patients with left ventricular assist devices (LVADs) is increasing each year. Despite a lack of evidence, many emergency medical systems and hospitals have recommended against performing chest compressions in these patients. This deviation from conventional resuscitation algorithms is secondary to concern that chest compressions could dislodge the LVAD.

Objective

To assess whether cannula dislodgment occurred in LVAD patients receiving chest compressions.

Methods

We retrospectively analyzed the outcomes of all LVAD patients who received chest compressions for cardiac arrest over a four year period in a large urban hospital. Eight cases were reviewed for both cannula integrity and outcomes.

Results

Using autopsy and adequate flow through device as proxy for intact inflow/outflow cannulas, none of the eight patients receiving chest compressions had cannula dislodgment. Four of the 8 patients had return of neurologic function.

Conclusions

In this small retrospective case series, standard chest compressions in patients with LVADs did not cause cannula dislodgment. More research is necessary to determine the utility of chest compressions in the LVAD population.     

Systematic review of quality of life and other patient-centred outcomes after cardiac arrest survival

Objectives

In cardiac arrest patients (in hospital and pre hospital) does resuscitation produce a good Quality of Life (QoL) for survivors after discharge from the hospital?

Methods

Embase, Medline, The Cochrane Database of Systematic Reviews, Academic Search Premier, the Central Database of Controlled Trials and the American Heart Association (AHA) Resuscitation Endnote Library were searched using the terms (‘Cardiac Arrest’ (Mesh) OR ‘Cardiopulmonary Resuscitation’ (Mesh) OR ‘Heart Arrest’ (Mesh)) AND (‘Outcomes’ OR ‘Quality of Life’ OR ‘Depression’ OR ‘Post-traumatic Stress Disorder’ OR ‘Anxiety OR ‘Cognitive Function’ OR ‘Participation’ OR ‘Social Function’ OR ‘Health Utilities Index’ OR ‘SF-36’ OR ‘EQ-5D’ as text term.

Results

There were 9 inception (prospective) cohort studies (LOE P1), 3 follow up of untreated control groups in randomised control trials (LOE P2), 11 retrospective cohort studies (LOE P3) and 47 case series (LOE P4). 46 of the studies were supportive with respect to the search question, 17 neutral and 7 negative.

Discussion

The majority of studies concluded that QoL after cardiac arrest is good. This review demonstrated a remarkable heterogeneity of methodology amongst studies assessing QoL in cardiac arrest survivors. There is a requirement for consensus development with regard to quality of life and patient centred outcome assessment in this population.     

Global and regional differences in cerebral blood flow after asphyxial versus ventricular fibrillation cardiac arrest in rats using ASL-MRI

Both ventricular fibrillation cardiac arrest (VFCA) and asphyxial cardiac arrest (ACA) are frequent causes of CA. However, only isolated reports compared cerebral blood flow (CBF) reperfusion patterns after different types of CA, and even fewer reports used methods that allow serial and regional assessment of CBF. We hypothesized that the reperfusion patterns of CBF will differ between individual types of experimental CA. In a prospective block-randomized study, fentanyl-anesthetized adult rats were subjected to 8 min VFCA or ACA. Rats were then resuscitated with epinephrine, bicarbonate, manual chest compressions and mechanical ventilation. After the return of spontaneous circulation, CBF was then serially assessed via arterial spin-labeling magnetic resonance imaging (ASL-MRI) in cortex, thalamus, hippocampus and amygdala/piriform complex over 1 h resuscitation time (RT). Both ACA and VFCA produced significant temporal and regional differences in CBF. All regions in both models showed significant changes over time (p < 0.01), with early hyperperfusion and delayed hypoperfusion. ACA resulted in early hyperperfusion in cortex and thalamus (both p < 0.05 vs. amygdala/piriform complex). In contrast, VFCA induced early hyperperfusion only in cortex (p < 0.05 vs. other regions). Hyperperfusion was prolonged after ACA, peaking at 7 min RT (RT7; 199% vs. BL, Baseline, in cortex and 201% in thalamus, p < 0.05), then returning close to BL at ∼RT15. In contrast, VFCA model induced mild hyperemia, peaking at RT7 (141% vs. BL in cortex). Both ACA and VFCA showed delayed hypoperfusion (ACA, ∼30% below BL in hippocampus and amygdala/piriform complex, p < 0.05; VFCA, 34–41% below BL in hippocampus and amygdala/piriform complex, p < 0.05). In conclusion, both ACA and VFCA in adult rats produced significant regional and temporal differences in CBF. In ACA, hyperperfusion was most pronounced in cortex and thalamus. In VFCA, the changes were more modest, with hyperperfusion seen only in cortex. Both insults resulted in delayed hypoperfusion in all regions. Both early hyperperfusion and delayed hypoperfusion may be important therapeutic targets.     

Resuscitation great. A history of mechanical devices for providing external chest compressions

The importance of providing good quality chest compressions with limited interruptions has been emphasised by the Resuscitation Guidelines 2005. The difficulties of providing consistent, good quality, chest compressions manually are well documented and attempts have been made to devise mechanical means to achieve this. Many see the development of mechanical devices as a new phenomenon; however, as with many other components of resuscitation science, they have in fact been available for a number of years. This paper provides a brief historical review of some of the mechanical devices which have been invented over the last 45 years in order to deliver external chest compressions. It also suggests some reasons why these devices failed to become a regular part of resuscitation practice.     

Rapidly induced selective cerebral hypothermia using a cold carotid arterial flush during cardiac arrest in a dog model

PURPOSE: The present study was undertaken to determine whether flushing the carotid artery with normal saline at 4 degrees C (hypothermic carotid arterial flush, HCAF) during cardiac arrest can achieve selective cerebral hypothermia rapidly during cardiac arrest and improve cerebral outcome. METHODS: Ventricular fibrillation (VF) was induced in fourteen dogs and circulatory arrest was maintained for 9 min. Dogs were then resuscitated by cardiopulmonary resuscitation. The dogs were divided into two groups; a control group (n=7), which underwent precisely the same procedure as the experimental group but not HCAF, and an experimental group (HCAF group; n=7), which received HCAF from 8 min after the onset of VF. RESULTS: Two dogs in the control group and in the HCAF group died within 72 h after the recovery of spontaneous circulation (ROSC) due to extracerebral complications. The remaining 10 dogs survived to final evaluation at 72 h post-ROSC. In the HCAF group, tympanic temperature decreased from 37.7 degrees C (37.5-37.8) to 34 degrees C in 1 min (1-1.5) from the start of HCAF and was maintained below 34 degrees C until 6.5 min (3-12) after the start of HCAF, whereas oesophageal and rectal temperatures were maintained above 35 degrees C. Neurological deficit scores (0-100%) at 72 h post-ROSC were 42.4% (27.0-80.6) in the control group and 18.4% (14.0-36.0) in the HCAF group (p<0.05). CONCLUSION: HCAF induced selective cerebral hypothermia rapidly during cardiac arrest and improved neurological deficit scores after 9 min of no blood flow in the described canine cardiac arrest model.