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 resuscitation

Cardiopulmonary resuscitation (CPR) is a technique used in both human and veterinary medicine. Although a number of innovative adaptations to CPR have been researched, the mainstay of CPR remains intubation, adequate ventilation, chest compressions, and basic drug therapy. The purpose of this article is to review the techniques and drugs commonly used in both closed chest and open chest CPR.     

Antimicrobial therapy in neonatal foals

There are several differences in treatment of neonatal foals with antimicrobials, compared to mature horses. Firstly, the dose of many antimicrobials is different in the foal. For orally administered drugs, this may also affect their efficacy, due to different enteral absorption. Secondly, neonatal foals are not yet hindgut fermentors and this allows antimicrobials with a high propensity to cause colitis in mature horses to be used. Thirdly, toxicities are different and some antimicrobials used in mature horses, such as enrofloxacin, are not suitable for use in foals. Foal-specific information is therefore needed for their safe and effective treatment with antimicrobials.     

Iron toxicity in neonatal foals

Newborn Shetland foals died of acute hepatic failure following oral administration of approximately 16 mg/kg body weight ferrous fumarate. Lesions in these foals were indistinguishable from lesions in foals given an oral digestive inoculant containing ferrous fumarate and were also similar to the syndrome characterised as 'toxic hepatopathy' in foals in the United States in 1983. We conclude that foals are susceptible to toxicity from low doses of iron compounds in the first few days of life. Vitamin E and selenium deficiency may contribute to this susceptibility.     

Musculoskeletal disorders in neonatal foals

Angular limb deformities are not uncommon in foals. Mild angular deviation due to laxity of supporting soft tissues often resolves spontaneously. However, external splinting or casting may be needed in severe cases or in those that do not resolve. When incomplete ossification of carpal or tarsal bones is the cause of the limb deformity, external support is mandatory to prevent further deformation and abnormal development of the bones. When epiphyseal and metaphyseal abnormalities cause axial deviation, surgical intervention is usually necessary. Circumferential periosteal transection and/or transphyseal bridging are methods used. The choice is dictated by the type and severity of the deformity. Flexor contractures of the forelimb vary greatly in degree and joints affected. Physical therapy combined with intermittent splint application is often successful, but surgical intervention may be necessary in unresponsive cases. Flexor tendon laxity is usually self-correcting but physical therapy, restricted exercise, and splinting may be needed. Rotational abnormalities are easier to correct in the forelimbs than in the hind limbs. Correction is usually accomplished by frequent corrective hoof trimming. Miscellaneous anomalies of the musculoskeletal system may sometimes be amenable to surgical correction, although the potential disadvantages must be carefully considered. Septic arthritis is a frequent sequela to neonatal septicemia and must be treated aggressively and early in its development. Appropriate systemic antibiotics, joint lavage, and rest are indicated. Neonatal osteomyelitis has a poor prognosis and requires prompt, vigorous therapy; even then, growth anomalies of the limb or contiguous septic arthritis may develop and further worsen the prognosis. Early accurate diagnosis and prompt appropriate therapy are vital in treating musculoskeletal disorders in foals, especially when a successful outcome is judged by the animal becoming a functional athlete.     

Anesthesia for neonatal foals

A brief discussion of those aspects of neonatal physiology that pertain to anesthetic risk and selection of anesthetic techniques is followed by discussion of suggested techniques for anesthetic management in healthy foals. Preoperative preparation and management of foals with selected serious surgical conditions are also considered.     

Cardiopulmonary effects and recovery characteristics associated with 2 sedative protocols for assisted ventilation in healthy neonatal foals

Neonatal foals may require prolonged sedation to permit ventilatory support in the first few days of life. The objective of this study was to evaluate and compare the cardiopulmonary effects and clinical recovery characteristics of 2 sedative/analgesia protocols in healthy foals receiving assisted ventilation. Foals were randomized to receive dexmedetomidine, butorphanol, and propofol (DBP) or midazolam, butorphanol, and propofol (MBP) during a 24-hour period. Infusion rates of dexmedetomidine, midazolam, and propofol were adjusted and propofol boluses administered according to set protocols to maintain optimal sedation and muscle relaxation. Ventilatory support variables were adjusted to preset targets. Physiologic variables were recorded, cardiac output (CO) measured (thermodilution), and arterial and mixed venous blood collected for gas analysis at intervals up to 24 hours. Foals in group DBP received dexmedetomidine [2.4 ± 0.5 μg/kg body weight (BW) per hour], butorphanol (13 μg/kg BW per hour), and propofol (6.97 ± 0.86 mg/kg BW per hour), whereas foals in group MBP received midazolam (0.14 ± 0.04 mg/kg BW per hour), butorphanol (13 μg/kg BW per hour), and propofol (5.98 ± 1.33 mg/kg BW per hour). Foals in the DBP group received significantly more propofol boluses (9.0 ± 3.0) than those in the MBP group (4.0 ± 2.0). Although physiologic variables remained within acceptable limits, heart rate (HR), mean arterial pressure (MAP), and cardiac index (CI) were lower in foals in the DBP group than in the MBP group. Times to sternal recumbency, standing, and nursing were significantly shorter in the DBP than MBP group. We found that MBP and DBP protocols are suitable to assist ventilatory support in neonatal foals, although MBP results in a prolonged recovery compared to DBP.     

Subconjunctival haemorrhages in neonatal thoroughbred foals

A survey of 169 neonatal thoroughbred foals revealed that 8.3 per cent had subconjunctival haemorrhages, but there was no indication of a relationship between retinal and subconjunctival haemorrhages. The haemorrhages were not related to any abnormality of the foals and there was no sex or eye predisposition. In most cases the haemorrhages were fresh and red, occurred mainly dorsally or dorsonasally and extended up to the limbus; they resolved completely within four to 10 days, depending on their initial severity and extent. They had no effect on the foals' vision in the short or long term. The incidence of subconjunctival haemorrhages was associated with foaling category, multiparity and country of birth.     

Abdominal surgery in neonatal foals.

Abdominal surgery in foals under 30 days old has become more common with improved neonatal care. Early recognition of a foal at risk and better nursing care have increased the survival rates of foals that require neonatal care. The success of improved neonatal care also has increased the need for accurate diagnosis and treatment of gastrointestinal, umbilical, and bladder disorders in these foals. This chapter focuses on the early and accurate diagnosis of specific disorders that require abdominal exploratory surgery and the specific treatment considerations and prognosis for these disorders.     

Immunologic disorders in neonatal foals.

Foals live in an environment heavily populated by bacteria, many of which are capable of causing disease. Development of infection,however, is the exception rather than the rule. The ability of the foal to prevent infection by most pathogens is the result of a sophisticated set of defense mechanisms. These defense mechanisms can be divided into adaptive and innate immunity. Innate immunity encompasses defense mechanisms that pre-exist or are rapidly induced within hours of exposure to a pathogen. Conversely, adaptive or acquired immunity represents host defenses mediated by T and B lymphocytes, each expressing a highly specific antigen receptor and exhibiting memory during a second encounter with a given antigen. Immunologic disorders are relatively common in foals compared with their occurrence in adult horses. This article summarizes the current understanding of the equine fetal and neonatal immune system and reviews common immunodeficiency disorders as well as disorders resulting from allogenic incompatibilities.     

Orthopedic disorders in neonatal foals.

The first month of life is a vulnerable time for foals. They must adjust to their environment while they are still compromised immunologically, and their musculoskeletal system is rapidly growing and adjusting to stresses from an increasing amount of exercise. Therefore, if a foal is born with or acquires an abnormality or disease related to the musculoskeletal system, rapid adjustments must be made to allow the foal to grow and respond so that future athletic performance will not be compromised. Problems must be identified early, which requires thorough examinations. This article summarizes treatment options for orthopedic disorders that present or become clinically evident within the first month of life.     

Cardiopulmonary resuscitation: current recommendations

Early recognition of CPA is the key to its successful management. For resuscitation to be managed successfully, effective forward blood flow must be established at the onset of the arrest. In our clinical experience, we have found that the Doppler unit allows us to assess the effectiveness of cerebral perfusion better than any other method of blood pressure evaluation. If, by Doppler monitoring results, cerebral perfusion is found to be poor, blood flow may be mechanically improved by instituting high dose epinephrine therapy and interposed abdominal counter-pressure techniques. There is an understandable reluctance on the part of many veterinarians to enter the chest in the course of CPR. Unfortunately, this delay in performing internal compressions is often the reason that open-chest CPR is deemed ineffective by so many practitioners. If external chest CPR is not effective within 1 to 2 min (maximum) of its initiation, an emergency thoracotomy and direct cardiac massage should be performed. We know that perfusion pressure increases three to five times with open versus closed-chest CPR. This improvement in perfusion with direct cardiac massage is due, in part, to the absence of venous pressure elevations created during external chest compression. It follows that better coronary and cerebral blood flow will result in better resuscitation when direct cardiac massage is performed early. The "bottom line" in CPR is successful resuscitation of the patient with resultant good neurologic function. It is hoped that through the use of these techniques and new cytoprotective drugs, the survival rate will rise.     

Suspected primary lactose intolerance in neonatal foals

The intestine of neonatal mammals must be able to secrete lactase enzyme to hydrolyse lactose in its mother's milk. Failure to secrete lactase results in failure to digest lactose. This results in osmotic diarrhoea, weight loss, failure to thrive, lethargy, colic and abdominal distension. Lactose intolerance may occur secondarily to intestinal bacterial infection. Primary lactose intolerance is recognised in human infants. Here we report 2 cases of suspected primary lactose intolerance in foals. The foals responded well to oral administration of exogenous lactase enzyme.     

Glucose metabolism in five septic neonatal foals

Objective: Glucose metabolism is often deranged in septic animals. Bacteremia and sepsis are common in foals and clinical experience suggests that glucose metabolism is abnormal in some of these animals. The purpose of this study was to provide initial estimates of rates of glucose appearance, disappearance, and metabolic clearance rate in septic foals.
Series Summary: Rates of glucose entry, and exit from blood were determined by use of infusion of isotopically labeled glucose in 5 foals with confirmed sepsis. Serum concentrations of glucose, insulin, glucagon, and cortisol were measured concurrent with measurement of rates of glucose turnover. Median glucose turnover rate was 24 μmol/kg/min (range 17–53 μmol/kg/min), and median glucose metabolic clearance rate was 3.2 mL/kg/min (range 1.7–6.7 mL/kg/min). Median concentration of serum immunoreactive insulin was 55 pmol/L (range 36–190 pmol/L), median serum immunoreactive glucagon was 65 pmol/L (range 19–120 pmol/L), and median serum cortisol was 207 nmol/L (range 100–333 nmol/L).
New or unique information provided: These data, although limited in scope and by the lack of data in healthy foals, demonstrate the magnitude and variation in glucose appearance, disappearance, and metabolic clearance rate in septic foals, provide an estimate of rates of glucose utilization in sick foals, and will be useful in guiding future studies of energy metabolism in healthy and ill foals.     

Cardiopulmonary resuscitation with vasopressin in a dog

That endogenous vasopressin levels in successfully resuscitated human patients were significantly higher than in patients who died pointed to the possible benefit of administering vasopressin during cardiopulmonary resuscitation (CPR). Several CPR studies in pigs showed that vasopressin improved blood flow to vital organs, cerebral oxygen delivery, resuscitability and neurological outcome when compared with epinephrine. In a small clinical study, vasopressin significantly improved short-term survival when compared with epinephrine indicating its potential as an alternative pressor to epinephrine during CPR in human beings. As there was little clinical data available at that time, its recommended use was limited to adult human beings with shock-refractory ventricular fibrillation. In this report, we present the case of a dog in which the successful management of intraoperative asystolic cardiac arrest involved vasopressin. Unexpected cardiac arrest occurred during anaesthesia for the surgical removal of multiple mammary adenocarcinomata in a 11-year-old Yorkshire terrier. Despite an ASA physical status assignation of III, the dog was successfully resuscitated with external chest compressions, intermittent positive pressure ventilation and vasopressin (2 doses of 0.8 IU kg(-1)) and was discharged 3 days later without signs of neurological injury. We believe vasopressin contributed to restoring spontaneous circulation. It may prove increasingly useful in perioperative resuscitation in dogs.