Application of impedance threshold devices during cardiopulmonary cerebral resuscitation

Objective – To review the use of impedance threshold devices (ITD) during CPCR, their proposed mechanism of action, and their application in veterinary medicine. Data Sources – Data sources include scientific reviews and original research publications using the PubMed search engine with the following keywords: ‘impedance threshold device’ and ‘resuscitation’ and the Veterinary Information Network search function using the keywords ‘impedance threshold device.’ Human Data Synthesis – Studies in human medicine have demonstrated that the use of an ITD during CPCR in patients during out‐of‐hospital cardiac arrest improves coronary perfusion pressure and cerebral perfusion pressure. This improvement in vital organ blood flow results in increased cardiac output and faster return of spontaneous circulation. The use of an ITD has been studied in people and currently holds a class IIb level of recommendation according to the 2010 American Heart Association Guidelines for CPR and Emergency Cardiovascular Care. This device is recommended as a way to improve hemodynamics during CPCR by enhancing venous return and avoiding hyperventilation, thereby increasing the likelihood of a successful resuscitation. Veterinary Data Synthesis – Multiple controlled studies using pigs with ventricular fibrillation induced cardiopulmonary arrest have demonstrated increased myocardial and cerebral perfusion with the use of an ITD. These studies have emphasized the importance of decreasing intrathoracic pressures during the decompression phase of CPCR and avoiding hyperventilation in order to maximize vital organ blood flow. Conclusions – Use of an ITD during CPCR in human and animal studies has demonstrated improved vital organ perfusion and faster return of spontaneous circulation. However, the majority of these studies have been carried out in people during out‐of‐hospital cardiac arrest and ventricular fibrillation cardiopulmonary arrest pig models. Further studies evaluating the use of an ITD during CPCR in the veterinary hospital setting are warranted.     

Respiratory and cardiopulmonary arrest in dogs and cats: 265 cases (1986-1991).

Outcomes of cardiopulmonary arrest and resuscitation in clinically affected dogs and cats have not been adequately studied. We examined the records from 200 dogs and 65 cats that had received cardiopulmonary resuscitation for respiratory or cardiopulmonary arrest; none of the animals had been anesthetized or intubated at the time of arrest, and all had been hospitalized in a veterinary critical care facility. Cardiopulmonary arrest was found to be more common than respiratory arrest in dogs and cats. Hospital discharge rates for animals with cardiopulmonary arrest ranged from 4.1% for dogs to 9.6% for cats, and were consistent with those reported from studies of human beings with cardiopulmonary arrest. Hospital discharge rates for dogs and cats with respiratory arrest were 28% and 58.3%, respectively.     

Successful cardiopulmonary resuscitation and use of short-term mechanical ventilation following inadvertent ketamine overdose in a cat

Objective: To describe the clinical manifestations and successful outcome following an inadvertent overdose of ketamine to a cat. Case summary: A 4‐year‐old neutered male domestic shorthair cat was evaluated for a urethral obstruction. Because of an inadvertent miscalculation of ketamine, 20 times the intended dose was administered intravenously, which resulted in cardiopulmonary arrest. Cardiopulmonary‐cerebral resuscitation was successful, and short‐term mechanical ventilation, fluids and intensive monitoring were utilized to achieve full recovery and subsequent discharge of the animal. New or unique information provided: Ketamine is a common anesthetic agent used in cats that is considered to have a wide therapeutic index and minimal cardiopulmonary depressant effects at recommended doses. Successful management of inadvertent ketamine overdose has been reported in children, but not in cats. Prompt CPCR and short‐term mechanical ventilation may be necessary to treat a significant ketamine overdose. In cats, yohimbine may act as a partial antagonist of ketamine.     

Survey of academic veterinarians' clinical practice in cardiopulmonary–cerebral resuscitation

Objective: To document the clinical practice of cardiopulmonary–cerebral resuscitation (CPCR) among academic veterinarians. Design: Survey. Setting: Eight colleges of veterinary medicine in the United States. Subjects: Two hundred and one academic veterinarians. Interventions: The survey was distributed by hand by the authors into the mailboxes of small animal faculty, residents, and interns. Demographic variables, questions regarding number of cardiopulmonary arrests (CPA) supervised and number successful, do not attempt resuscitation discussions, and Likert‐style questions about client presence during CPCR, appropriateness of CPCR, and CPCR decision‐making were included. Multiple linear regression models were constructed to determine the effect of multiple questions on different target variables of interest. Measurements and main results: Numerous differences were noted based on institution, gender, specialty, and position. Most institutions did not have a standard resuscitation consent form. Most respondents believed the client, house officer, and senior clinician should determine whether to perform resuscitation or not. Quality of life was the most significant determinant of whether to resuscitate or not, followed by long‐term prognosis, then short‐term prognosis. Conclusions: Veterinarians differ in many aspects of their approach to CPA and resuscitation. Creating consensus within the veterinary profession would benefit client service and patient care.     

Successful cardiopulmonary cerebral resuscitation incorporating defibrillation in a filly with neonatal maladjustment syndrome following a routine anaesthetic procedure

A 10-h-old 56-kg Thoroughbred filly was presented for treatment of partial failure of passive transfer of immunity and presumed neonatal maladjustment syndrome (NMS). The filly was hospitalised, and supportive care initiated. On Day 5 of hospitalisation, seizures were observed and were controlled with IV administration of diazepam. Due to progression of clinical signs of NMS, magnetic resonance imaging of the filly's brain was performed. During the early anaesthetic recovery period, the filly exhibited cardiopulmonary arrest (CPA) at which point cardiopulmonary cerebral resuscitation (CPCR) was performed for a total of 48 min. During this time, ventricular fibrillation (VF) was observed on ECG and the filly was defibrillated three times at 1–2-min intervals using 2–4 J/kg of monophasic electrical defibrillation. The filly successfully recovered from CPCR, was discharged 5 days later and was reported healthy 12 months post-discharge.     

Successful cardiopulmonary resuscitation in an adult horse following cardiovascular collapse on recovery from general anaesthesia in the Trendelenburg position

Equine anaesthesia is associated with a high risk of perioperative morbidity and mortality, particularly in the recovery period. Cardiovascular collapse and cardiopulmonary arrest (CPA) have been reported to account for one-third of anaesthesia-related perioperative deaths in the horse. This case report describes the successful cardiopulmonary resuscitation of a healthy adult Thoroughbred mare that developed cardiovascular collapse and subsequent CPA following positioning in the recovery box after general anaesthesia in the Trendelenburg position. Cardiopulmonary resuscitation (CPR) was instigated and included thoracic compressions, intermittent positive pressure ventilation and adrenaline administered via the intravenous and intra-tracheal routes. Return of spontaneous circulation (ROSC) was detected 5 min and 50 s after the start of CPR. A stable stance was achieved approximately 100 min after ROSC. The mare was discharged from the hospital 3 days later with no known complications. To the authors’ knowledge, this is the first case report documenting CPA following general anaesthesia in the Trendelenburg position in a horse, with subsequent successful CPR. The precise cause of the CPA is unknown but a number of plausible hypothesis are discussed including hypoventilation and a Bezold-Jarisch reflex.     

The use of vasopressin for treating vasodilatory shock and cardiopulmonary arrest

Objective – To discuss 3 potential mechanisms for loss of peripheral vasomotor tone during vasodilatory shock; review vasopressin physiology; review the available animal experimental and human clinical studies of vasopressin in vasodilatory shock and cardiopulmonary arrest; and make recommendations based on review of the data for the use of vasopressin in vasodilatory shock and cardiopulmonary arrest. Data Sources – Human clinical studies, veterinary experimental studies, forum proceedings, book chapters, and American Heart Association guidelines. Human and Veterinary Data Synthesis – Septic shock is the most common form of vasodilatory shock. The exogenous administration of vasopressin in animal models of fluid‐resuscitated septic and hemorrhagic shock significantly increases mean arterial pressure and improves survival. The effect of vasopressin on return to spontaneous circulation, initial cardiac rhythm, and survival compared with epinephrine is mixed. Improved survival in human patients with ventricular fibrillation, pulseless ventricular tachycardia, and nonspecific cardiopulmonary arrest has been observed in 4 small studies of vasopressin versus epinephrine. Three large studies, though, did not find a significant difference between vasopressin and epinephrine in patients with cardiopulmonary arrest regardless of initial cardiac rhythm. No veterinary clinical trials have been performed using vasopressin in cardiopulmonary arrest. Conclusion – Vasopressin (0.01–0.04 U/min, IV) should be considered in small animal veterinary patients with vasodilatory shock that is unresponsive to fluid resuscitation and catecholamine (dobutamine, dopamine, and norepinephrine) administration. Vasopressin (0.2–0.8 U/kg, IV once) administration during cardiopulmonary resuscitation in small animal veterinary patients with pulseless electrical activity or ventricular asystole may be beneficial for myocardial and cerebral blood flow.     

Cardiopulmonary cerebral resuscitation.

Cardiopulmonary arrest (CPA) is defined as the abrupt and unexpected cessation of spontaneous and effective ventilation and circulation. CPA can be the natural ending of a normal and long life; however, when CPA is the result of a reversible problem in an animal that has a treatable medical condition, rapid recognition and treatment may make the difference between a happy ending and premature death. Cardiopulmonary resuscitation provides artificial ventilation and circulation until advanced cardiac life support can be provided and spontaneous cardiopulmonary function is restored. The term cardiopulmonary cerebral resuscitation originated in the early 1960s in recognition of the severe central nervous system complications of prolonged cardiac arrest in human beings. Although neurologic complications of CPA may not be as noticeable in companion animals, newer brain-sparing strategies that recognize the consequences of reperfusion injury and the inflammatory cascade may some day offer improved survival.     

Cardiopulmonary cerebral resuscitation in neonatal foals

Cardiovascular or pulmonary system failure in neonatal foals requires rapid recognition and initiation of cardiopulmonary cerebral resuscitation (CPCR). Foals may require resuscitation immediately after birth or after arrest from progression of a disease process such as severe sepsis or septic shock. Initial treatment is aimed at establishing an airway and providing ventilation. Circulation is provided by closed-chest compressions. Circulatory access is important to provide intravenous fluid and pharmacologic therapy for cardiovascular support. Ventricular fibrillation and pulseless ventricular tachycardia are arrhythmias not commonly recognized with arrest in foals, whereas asystole and cardiovascular collapse are frequently encountered. Training of personnel, preparation of supplies, and organization during CPCR is essential to a successful outcome.Most of the information used for CPCR in neonatal foals is derived from human medical research and clinical medicine. As new advances are made in human neonatal and pediatric CPCR, many of these treatments and techniques can be applied to foals. This article reviews currently available CPCR guidelines in foals and highlights new perspectives in human medicine that may be applicable to foals.     

Survival and factors affecting survival in small ruminants and camelids attacked by dogs: 62 cases (1994–2004)

Objective: To determine the survival rates and factors affecting survival in small ruminants and camelids attacked by dogs. Design: Retrospective study. Setting: Two university teaching hospitals. Animals: Thirty goats, 28 sheep, 3 alpacas, and 1 llama. Measurements and main results: Medical records were reviewed to obtain signalment, time between injury and admission, hospitalization length, lesion site, treatment, complications, survival rate, and cost. Follow‐up information was obtained by telephone conversation with the owner. Sixty‐two patients met the inclusion criteria. Six animals were euthanized at admission and thus excluded. Of the 56 animals that were treated, 43 (77%) were discharged, 5 (9%) died, and 8 (14%) were euthanized. Animals that had thoracic or abdominal injuries, required surgery, or received more potent analgesic therapy were less likely to survive to discharge from hospital compared with animals that did not. Complications developed in 50 (82%) animals. Animals with respiratory complications were also less likely to survive to discharge from hospital than animals that did not. Long‐term follow up was available on 38/43 (88%) animals that were discharged. Thirty‐five of 38 (92%) animals were discharged and recovered from their injuries and 5 animals had long‐term complications. Conclusions: Small ruminants and camelids that are attacked by dogs have a good prognosis for short‐term survival. Short‐term survival is affected by lesion location and complications.     

Cardiopulmonary resuscitation in small animal medicine: an update

In December 2005, the American Heart Association published new guidelines for cardiopulmonary cerebral resuscitation (CPCR) in humans for the 1st time in 5 years. Many of the recommendations are based on research conducted in animal species and may be applicable to small animal veterinary patients. One important change that may impact how CPCR is performed in veterinary medicine is the recommendation to avoid administration of excessive ventilatory rates because this maneuver severely decreases myocardial and cerebral perfusion, decreasing the chance of survival. The new guidelines also emphasize the importance of providing well-executed, continuous, uninterrupted chest compressions. Interruption of chest compressions should be avoided and, if necessary, should be minimized to <10 seconds. During defibrillation, immediate resumption of chest compressions for 2 minutes after a single shock, before reassessment of the rhythm by ECG, is recommended. This recommendation replaces previous recommendations for the delivery of 3 defibrillatory shocks in rapid succession. Allowing permissive hypothermia postresuscitation has been found to be beneficial and may increase success rate. Medications utilized in cardiopulmonary resuscitation, including amiodarone, atropine, epinephrine, lidocaine, and vasopressin, along with the indications, effects, routes of administration, and dosages, are discussed. The application of the new guidelines to veterinary medicine as well as a review of cardiopulmonary resuscitation in small animals is provided.     

Prevalence and factors associated with initial and subsequent shockable cardiac arrest rhythms and their association with patient outcomes in dogs and cats undergoing cardiopulmonary resuscitation: A RECOVER registry study

Objective

To report the prevalence of initial shockable cardiac arrest rhythms (I-SHKR), incidence of subsequent shockable cardiac arrest rhythms (S-SHKR), and factors associated with I-SHKRs and S-SHKRs and explore their association with return of spontaneous circulation (ROSC) rates in dogs and cats undergoing CPR.

Design

Multi-institutional prospective case series from 2016 to 2021, retrospectively analyzed.

Setting

Eight university and eight private practice veterinary hospitals.

Animals

A total of 457 dogs and 170 cats with recorded cardiac arrest rhythm and event outcome reported in the Reassessment Campaign on Veterinary Resuscitation CPR registry.

Measurements and Main Results

Logistic regression was used to evaluate association of animal, hospital, and arrest variables with I-SHKRs and S-SHKRs and with patient outcomes. Odds ratios (ORs) were generated, and significance was set at P < 0.05. Of 627 animals included, 28 (4%) had I-SHKRs. Odds for I-SHKRs were significantly higher in animals with a metabolic cause of arrest (OR 7.61) and that received lidocaine (OR 17.50) or amiodarone (OR 21.22) and significantly lower in animals experiencing arrest during daytime hours (OR 0.22), in the ICU (OR 0.27), in the emergency room (OR 0.13), and out of hospital (OR 0.18) and that received epinephrine (OR 0.19). Of 599 initial nonshockable rhythms, 74 (12%) developed S-SHKRs. Odds for S-SHKRs were significantly higher in animals with higher body weight (OR 1.03), hemorrhage (OR 2.85), or intracranial cause of arrest (OR 3.73) and that received epinephrine (OR 11.36) or lidocaine (OR 18.72) and significantly decreased in those arresting in ICU (OR 0.27), emergency room (OR 0.29), and out of hospital (OR 0.38). Overall, 171 (27%) animals achieved ROSC, 81 (13%) achieved sustained ROSC, and 15 (2%) survived. Neither I-SHKRs nor S-SHKRs were significantly associated with ROSC.

Conclusions

I-SHKRs and S-SHKRs occur infrequently in dogs and cats undergoing CPR and are not associated with increased ROSC rates.     

Intraosseous injection during cardiopulmonary resuscitation in dogs

Five mixed breed dogs were used to investigate the feasibility of femoral intraosseous injection during cardiac arrest. The intraosseous route was evaluated in the anaesthetised dogs after induction of cardiac arrest. Fluorescein dye was injected through pre-placed intraosseous catheters during cardiac massage. The dye was detected at the membrana nictitans five to 12 seconds later indicating successful transfer from the femoral marrow cavity to the systemic circulation during cardiopulmonary resuscitation (CPR). The clinical value of intraosseous injection during CPR is discussed and compared with the endotracheal administration of drugs.     

Postoperative pulmonary complications in dogs undergoing laparotomy: frequency, characterization and disease-related risk factors

Objective: To determine the frequency of postoperative pulmonary complications (PPCs) in dogs following laparotomy, characterize the nature of PPCs, and identify disease‐related risk factors for PPCs in dogs. Design: Retrospective clinical study. Setting: University‐affiliated small animal teaching hospital. Animals: One hundred and sixty‐two dogs without preoperative pulmonary pathology that underwent laparotomy surgery. Interventions: None. Measurements and main results: Cases were evaluated for factors including patient signalment, preexisting disease, primary and ancillary surgical procedure(s), development of postoperative pulmonary disease, characteristics of perioperative hospitalization and therapy, and survival. Twenty‐two percent of dogs in the study developed PPCs. PPCs included respiratory arrest (n=4), acute respiratory distress syndrome (ARDS) (n=3), pneumonia (n=8), hypoventilation (n=13), and transient hypoxemia (n=8). Dogs that developed PPCs had a significantly longer duration of oxygen therapy, longer duration of stay in intensive care unit (ICU), and decreased survival. Dogs with perioperative vomiting or regurgitation were more likely to develop PPCs. Animals that underwent exploratory laparotomy for biliary or septic peritonitis were also more likely to develop PPCs. Conclusions: PPCs occur in dogs following laparotomy and contribute significantly to the morbidity and mortality of these surgical patients. In this patient population, animals with vomiting, regurgitation, or peritonitis may be at a higher risk of developing PPCs. Animals with the identified risk factors should be monitored carefully postoperatively for development of pulmonary complications.     

Survival Following Cardiopulmonary Resuscitation in Dogs and Cats

Dogs and cats receiving cardiopulmonary resuscitation (CPR) were evaluated for factors leading to cardiac arrest and for survival following the procedure. One-hundred-thirty-five canine and forty-three feline patients seen at the University of California, Davis Veterinary Medical Teaching Hospital that received CPR between August 1987 and December 1991 were studied. Initial resuscitation attempts were unsuccessful in 72% of dogs and 58% of cats. Five dogs and one cat were still alive 3 days after CPR. Ultimately only four dogs and one cat were discharged from the hospital alive. These five patients with uniquely longer survival all had cardiac arrests associated with drug and/or anesthetic reactions.     

The clinical practice of CPCR in small animals: an internet‐based survey

Objective – To characterize the provision of CPCR by small animal veterinarians in clinical practice and to assess how this practice varies among different levels of expertise. Design – Internet‐based survey. Setting – Academia, referral practice, and general practice. Subjects – Six hundred and two small animal veterinarians in clinical practice. Respondents were grouped a priori according to level of expertise: board‐certified (ACVECC, ACVA, ECVAA) specialists; general practitioners in emergency clinics; general practitioners in general practice (GPG). Interventions – Email invitations to the online questionnaire were disseminated via a veterinary internet platform and mailing list server discussion groups. Questions explored respondent characteristics, CPCR preparedness, infrastructural and personnel resources, and techniques of basic and advanced life support. Main Results – In this group of practitioners, the majority (65%) were in general practice. GPG were more likely to perform CPCR <5 times per year and to have 3 or fewer members on their resuscitation team. Most practitioners have a crash cart and drug‐dosing chart available. GPG were less likely to obtain resuscitation codes on their patients, and less likely to use end‐tidal carbon dioxide monitoring or defibrillation. Intubation, oxygen supplementation, vascular access, and external thoracic compressions were widely used, however, GPG were more likely to use lower chest compression rates. Drugs used for CPCR differed among the groups with GPG more likely to use doxapram and glucocorticoids. Conclusions – CPCR is heterogeneously performed in small animal veterinary medicine; differences exist, both among and within different types of veterinarians with varying levels of expertise, in respect to available infrastructure, personnel and CPCR techniques used.