The natural biochemical changes during ventricular fibrillation with cardiopulmonary resuscitation and the onset of postdefibrillation pulseless electrical activity

2024 RECOVER Guidelines: Monitoring. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review evidence on and devise treatment recommendations for patient monitoring before, during, and following CPR in dogs and cats, and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to peri-CPR monitoring following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by Monitoring Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk:benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Thirteen questions pertaining to hemodynamic, respiratory, and metabolic monitoring practices for identification of cardiopulmonary arrest, quality of CPR, and postcardiac arrest care were examined, and 24 treatment recommendations were formulated. Of these, 5 recommendations pertained to aspects of end-tidal CO2 (ETco2) measurement. The recommendations were founded predominantly on very low quality of evidence, with some based on expert opinion.

CONCLUSIONS

The Monitoring Domain authors continue to support initiation of chest compressions without pulse palpation. We recommend multimodal monitoring of patients at risk of cardiopulmonary arrest, at risk of re-arrest, or under general anesthesia. This report highlights the utility of ETco2 monitoring to verify correct intubation, identify return of spontaneous circulation, evaluate quality of CPR, and guide basic life support measures. Treatment recommendations further suggest intra-arrest evaluation of electrolytes (ie, potassium and calcium), as these may inform outcome-relevant interventions.

Serial paired arterial and jugular venous point-of-care values in dogs undergoing manual basic life support

OBJECTIVE

To evaluate differences in point-of-care (POC) variables obtained from arterial and jugular venous blood in dogs undergoing manual basic life support (BLS) and report changes over time.

DESIGN

Experimental study.

SETTING

Small animal research facility.

ANIMALS

Twenty-four purpose-bred research dogs.

INTERVENTIONS

Dogs were anesthetized, and arterial catheters were placed before euthanasia. One minute after cardiopulmonary arrest, BLS consisting of manual chest compressions and ventilation delivered via endotracheal intubation, face mask, mouth-to-nose, or no ventilation was initiated. Paired arterial and jugular venous blood samples were obtained for POC testing before euthanasia (T0), at 3 minutes (T3), and at 6 minutes (T6) into BLS.

MEASUREMENTS AND MAIN RESULTS

The association of POC variables with arterial or venous sample type while controlling for type of ventilation and sampling timepoint was determined using a generalized linear mixed model. Variables obtained from arterial and venous blood samples were compared over time using repeated measures ANOVA or Friedman test. Pao2, anion gap, potassium, chloride, glucose concentration, and PCV were significantly higher in arterial blood samples compared with venous samples (P < 0.03). By T6, arterial glucose concentration, arterial and venous base excess, venous pH, and plasma lactate, potassium, creatinine, bicarbonate, and sodium concentrations were significantly increased, and arterial and venous Po2, ionized calcium concentration, PCV, and total plasma protein concentration were significantly decreased from T0 (P < 0.05).

CONCLUSIONS

Although statistically significant, arteriovenous differences and changes in POC blood variables during BLS were small and not clinically relevant over time. Given the challenges of arterial blood sampling, it may be reasonable to pursue venous blood sampling during CPR. Further studies in dogs undergoing BLS and advanced life support are needed to better understand the potential clinical role of POC testing during CPR.

Association of point-of-care blood variables obtained from dogs and cats during cardiopulmonary resuscitation and following return of spontaneous circulation with patient outcomes

OBJECTIVE

To investigate the association of point-of-care biochemical variables obtained during CPR or within 24 hours of return of spontaneous circulation (ROSC) with patient outcomes.

DESIGN

Retrospective study.

SETTING

University teaching hospital.

ANIMALS

Ninety-four dogs and 27 cats undergoing CPR according to the Reassessment Campaign on Veterinary Resuscitation guidelines.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood gas, acid-base, electrolyte, glucose, and plasma lactate values obtained during CPR or within 24 hours of ROSC were retrospectively evaluated and are described. The blood sample type and collection time with respect to CPR initiation and ROSC were recorded. Measured variables, collection times, and species were included in a multivariable logistic regression model to estimate the odds ratio (OR) and 95% confidence interval of ROSC, sustained ROSC (≥20 min), and survival to hospital discharge. Significance was set at P < 0.05. Seventy-two venous blood samples obtained during CPR and 45 first venous and arterial blood samples obtained after ROSC were included in logistic regression analysis. During CPR, PvO₂ (1.09 [1.036-1.148], P = 0.001) and venous standard base excess (SBE) (1.207 [1.094-1.331], P < 0.001) were associated with ROSC. PvO₂ (1.075 [1.028-1.124], P = 0.002), SBE (1.171 [1.013-1.353], P = 0.032), and potassium concentration (0.635 [0.426-0.946], P = 0.026) were associated with sustained ROSC. Potassium concentration (0.235 [0.083-0.667], P = 0.007) was associated with survival to hospital discharge. Following ROSC, pH (69.110 [4.393-1087], P = 0.003), potassium concentration (0.222 [0.071-0.700], P = 0.010), and chloride concentration (0.805 [0.694-0.933], P = 0.004) were associated with survival to hospital discharge.

CONCLUSIONS

Biochemical variables such as PvO₂ , SBE, and potassium concentration during CPR and pH, potassium, and chloride concentration in the postarrest period may help identify dogs and cats with lower odds for ROSC or survival to hospital discharge following CPR.

Importance of the pig as a human biomedical model

[Figure: see text].

Serum potassium level on hospital arrival and survival after out-of-hospital cardiac arrest: The CRITICAL study in Osaka, Japan

BACKGROUND

Little is known about the association between serum potassium level on hospital arrival and neurological outcome after out-of-hospital cardiac arrest (OHCA). We investigated whether the serum potassium level on hospital arrival had prognostic indications for patients with OHCA.

METHODS

This prospective, multicenter observational study conducted in Osaka, Japan (CRITICAL study) enrolled consecutive patients with OHCA transported to 14 participating institutions from 2012 to 2016. We included adult patients aged ⩾18 years with OHCA of cardiac origin who achieved return of spontaneous circulation and whose serum potassium level on hospital arrival was available. Based on the serum potassium level, patients were divided into four quartiles: Q1 (K ⩽3.8 mEq/L), Q2 (3.8< K⩽4.5 mEq/L), Q3 (4.5< K⩽5.6 mEq/L) and Q4 (K >5.6 mEq/L). The primary outcome was one-month survival with favorable neurological outcome, defined as cerebral performance category scale 1 or 2.

RESULTS

A total of 9822 patients were registered, and 1516 of these were eligible for analyses. The highest proportion of favorable neurological outcome was 44.8% (189/422) in Q1 group, followed by 30.3% (103/340), 11.7% (44/375) and 4.5% (17/379) in the Q2, Q3 and Q4 groups, respectively (p<0.001). In the multivariable analysis, the proportion of favorable neurological outcome decreased as the serum potassium level increased (p<0.001).

CONCLUSIONS

High serum potassium level was significantly and dose-dependently associated with poor neurological outcome. Serum potassium on hospital arrival would be one of the effective prognostic indications for OHCA achieving return of spontaneous circulation.

Modeling cardiac arrest and resuscitation in the domestic pig

Cardiac arrest remains a leading cause of death and permanent disability worldwide. Although many victims are initially resuscitated, they often succumb to the extensive ischemia-reperfusion injury inflicted on the internal organs, especially the brain. Cardiac arrest initiates a complex cellular injury cascade encompassing reactive oxygen and nitrogen species, Ca²⁺ overload, ATP depletion, pro- and anti-apoptotic proteins, mitochondrial dysfunction, and neuronal glutamate excitotoxity, which injures and kills cells, compromises function of internal organs and ignites a destructive systemic inflammatory response. The sheer complexity and scope of this cascade challenges the development of experimental models of and effective treatments for cardiac arrest. Many experimental animal preparations have been developed to decipher the mechanisms of damage to vital internal organs following cardiac arrest and cardiopulmonary resuscitation (CPR), and to develop treatments to interrupt the lethal injury cascades. Porcine models of cardiac arrest and resuscitation offer several important advantages over other species, and outcomes in this large animal are readily translated to the clinical setting. This review summarizes porcine cardiac arrest-CPR models reported in the literature, describes clinically relevant phenomena observed during cardiac arrest and resuscitation in pigs, and discusses numerous methodological considerations in modeling cardiac arrest/CPR. Collectively, published reports show the domestic pig to be a suitable large animal model of cardiac arrest which is responsive to CPR, defibrillatory countershocks and medications, and yields extensive information to foster advances in clinical treatment of cardiac arrest.

Acid base, electrolyte, glucose, and lactate values during cardiopulmonary resuscitation in dogs and cats

OBJECTIVE

To report acid base, electrolyte, glucose, and lactate values collected during or immediately after cardiopulmonary resuscitation (CPR) in dogs and cats.

DESIGN

Retrospective study.

SETTING

University Teaching Hospital.

ANIMALS

Thirty-two dogs and 10 cats.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Blood gas, electrolyte, glucose, and lactate values measured during CPR or within 5 minutes of return of spontaneous circulation (ROSC) were retrospectively evaluated. The time of blood collection with respect to the occurrence of cardiopulmonary arrest (CPA), the initiation of CPR or ROSC was noted. Forty-two venous blood samples were analyzed, 24 collected during CPR and 18 samples were collected within 5 minutes of ROSC. Metabolic acidosis and hyperlactatemia were evident in all samples in the study while an increased PvCO2 occurred in 88% of samples collected during CPR and in 61% of samples collected following ROSC. Hyperkalemia occurred in 65% of all cases, decreased ionized calcium was evident in 18%, hypoglycemia was evident in 21% while hyperglycemia was evident in 62%. There was no significant difference in any parameter evaluated between dogs and cats during CPR. There was no significant difference of any variable measured during the first 15 minutes of CPA versus those measured more than 15 minutes following CPA. When the values measured during the first 5 minutes of ROSC were compared to those measured during CPR, the pH and PvO2 were significantly lower in the CPR group.

CONCLUSIONS

Biochemical abnormalities including metabolic acidosis, hyperkalemia, ionized hypocalcemia, hypoglycemia, and hyperglycemia can be identified during CPR and immediately following ROSC. The therapeutic and prognostic relevance of these changes are yet to be defined and may prove to be useful to guide patient management in the future.

β-Receptor blocker influences return of spontaneous circulation and chemical examination in rats during cardiopulmonary resuscitation

OBJECTIVE

We investigated the influence of β-receptor blocker metoprolol on return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR) in rats with induced myocardial infarction (MI).

METHODS

Male Sprague-Dawley rats were randomly divided into three groups: the sham-operated group, the MI group without metoprolol, which was fed the vehicle, and the MI+metoprolol group receiving intragastric metoprolol. Each group was further divided randomly into three subgroups, depending on the dosage of epinephrine administered during subsequent CPR applied after the induction of asphyxial cardiac arrest.

RESULTS

The ROSC rate was significantly decreased in the low dose subgroup of MI group, unchanged in the medium dose subgroup of MI group, and significantly decreased in the high dose subgroup of MI group, compared with the same dose subgroup of sham-operated group. MI+metoprolol group had a lower ROSC rate than MI group in the medium dose subgroup, and a higher ROSC rate than MI group in the high dose subgroup. There was no difference in blood K(+) values of successful rats between MI group and MI+metoprolol group. The rats with successful CPR had lower blood K(+) values than rats with unsuccessful CPR in each of the three treatment groups.

CONCLUSIONS

Metoprolol administered to MI rats over a long period significantly improved ROSC rates under an appropriate dose of epinephrine during CPR. An increasing high blood K(+) value would attenuate the rate of a successful CPR.

The dynamic pattern of end-tidal carbon dioxide during cardiopulmonary resuscitation: difference between asphyxial cardiac arrest and ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest

Introduction

Partial pressure of end-tidal carbon dioxide (PetCO2) during cardiopulmonary resuscitation (CPR) correlates with cardiac output and consequently has a prognostic value in CPR. In our previous study we confirmed that initial PetCO2 value was significantly higher in asphyxial arrest than in ventricular fibrillation/pulseless ventricular tachycardia (VF/VT) cardiac arrest. In this study we sought to evaluate the pattern of PetCO2 changes in cardiac arrest caused by VF/VT and asphyxial cardiac arrest in patients who were resuscitated according to new 2005 guidelines.

Methods

The study included two cohorts of patients: cardiac arrest due to asphyxia with initial rhythm asystole or pulseless electrical activity (PEA), and cardiac arrest due to arrhythmia with initial rhythm VF or pulseless VT. PetCO2 was measured for both groups immediately after intubation and repeatedly every minute, both for patients with or without return of spontaneous circulation (ROSC). We compared the dynamic pattern of PetCO2 between groups.

Results

Between June 2006 and June 2009 resuscitation was attempted in 325 patients and in this study we included 51 patients with asphyxial cardiac arrest and 63 patients with VF/VT cardiac arrest. The initial values of PetCO2 were significantly higher in the group with asphyxial cardiac arrest (6.74 ± 4.22 kilopascals (kPa) versus 4.51 ± 2.47 kPa; P = 0.004). In the group with asphyxial cardiac arrest, the initial values of PetCO2 did not show a significant difference when we compared patients with and without ROSC (6.96 ± 3.63 kPa versus 5.77 ± 4.64 kPa; P = 0.313). We confirmed significantly higher initial PetCO2 values for those with ROSC in the group with primary cardiac arrest (4.62 ± 2.46 kPa versus 3.29 ± 1.76 kPa; P = 0.041). A significant difference in PetCO2 values for those with and without ROSC was achieved after five minutes of CPR in both groups. In all patients with ROSC the initial PetCO2 was again higher than 1.33 kPa.

Conclusions

The dynamic pattern of PetCO2 values during out-of-hospital CPR showed higher values of PetCO2 in the first two minutes of CPR in asphyxia, and a prognostic value of initial PetCO2 only in primary VF/VT cardiac arrest. A prognostic value of PetCO2 for ROSC was achieved after the fifth minute of CPR in both groups and remained present until final values. This difference seems to be a useful criterion in pre-hospital diagnostic procedures and attendance of cardiac arrest.

Impact of Modified Treatment in Echocardiographically Confirmed Pseudo-Pulseless Electrical Activity in Out-of-Hospital Cardiac Arrest Patients with Constant End-Tidal Carbon Dioxide Pressure during Compression Pauses

This study evaluated the ability of focused echocardiography (FE) and capnography to differentiate between pulseless electrical activity (PEA) and pseudo-PEA in out-of-hospital cardiac arrest, and the potential survival benefits with modified treatment. In PEA patients with stable end-tidal carbon dioxide pressure ( PetCO2) during the compression pause and concomitant FE showing cardiac kinetic activity, the compression pause was prolonged for 15 s and an additional 20 IU vasopressin was administered. If pulselessness persisted, compressions were continued. Fifteen of the 16 patients studied (94%) achieved restoration of spontaneous circulation (ROSC); eight patients (50%) attained a good neurological outcome (Cerebral Performance Category 1–2). In an historical PEA group with stable PetCO2 values ( n = 48), ROSC was achieved in 26 patients (54%); four patients (8%) attained Cerebral Performance Category 1–2. Echocardiographical verification of the pseudo-PEA state enabled additional vasopressor treatment and cessation of chest compressions, and was associated with significantly higher rates of ROSC, survival to discharge and good neurological outcome.

Advances in swine biomedical model genomics

This review is a short update on the diversity of swine biomedical models and the importance of genomics in their continued development. The swine has been used as a major mammalian model for human studies because of the similarity in size and physiology, and in organ development and disease progression. The pig model allows for deliberately timed studies, imaging of internal vessels and organs using standard human technologies, and collection of repeated peripheral samples and, at kill, detailed mucosal tissues. The ability to use pigs from the same litter, or cloned or transgenic pigs, facilitates comparative analyses and genetic mapping. The availability of numerous well defined cell lines, representing a broad range of tissues, further facilitates testing of gene expression, drug susceptibility, etc. Thus the pig is an excellent biomedical model for humans. For genomic applications it is an asset that the pig genome has high sequence and chromosome structure homology with humans. With the swine genome sequence now well advanced there are improving genetic and proteomic tools for these comparative analyses. The review will discuss some of the genomic approaches used to probe these models. The review will highlight genomic studies of melanoma and of infectious disease resistance, discussing issues to consider in designing such studies. It will end with a short discussion of the potential for genomic approaches to develop new alternatives for control of the most economically important disease of pigs, porcine reproductive and respiratory syndrome (PRRS), and the potential for applying knowledge gained with this virus for human viral infectious disease studies.