Anesthetic management of the head trauma patient

Objective: To describe the optimal anesthetic management of patients with brain injury, with emphasis on the support of oxygen delivery to the brain, and the effects of anesthetic agents on cerebral perfusion. Data sources: Clinical and experimental studies from both the human and veterinary neuroanesthesia literature. Summary: The management of patients following primary traumatic brain injury (TBI) significantly impacts outcome. Outcome can be improved by strategies that improve oxygen delivery to the brain and prevent cerebral ischemia. Anesthetic agents have widely variable effects on the blood supply to the brain and, therefore, choice of anesthetic agent can influence neurological outcome. Although in the past, anesthetic agents have been selected for their neuroprotective properties, it is increasingly being recognized that the support of cerebral perfusion during anesthesia contributes more significantly to a positive outcome for these patients. Support of cardiorespiratory function is, therefore, highly important when anesthetizing patients with TBI. Conclusion: Choice of anesthetic agent is determined by the extent of brain injury and intracranial pressure (ICP) elevation. Factors that should be considered when anesthetizing head trauma patients include the effects of anesthetic agents on the cardiac and respiratory systems, their effects on cerebral blood flow (CBF), ICP, and possible neuroprotective benefits offered by certain agents.     

Anesthetic considerations for the geriatric patient

The geriatric patient presents an anesthetic challenge due to the physiologic alterations that occur during aging. The geriatric patient usually has an increased number of disease processes and does not possess the functional organ reserve capabilities compared to a younger patient. The geriatric patient seems more susceptible to the cardiopulmonary depressant effects of the preanesthetic and anesthetic agents in common use and, due to decreased hepatic function and other factors, may have a delayed recovery from these drugs. The preanesthetic and anesthetic drugs chosen for a geriatric patient will depend on that particular patient's physiologic status, the procedure to be done, and the experience of the veterinarian. Adequate fluid and monitoring support should always be provided for the geriatric patient.     

Anesthetic management of thoracotomy

Successful anesthesia for thoracic surgery requires an understanding of the clinical disease and the physiologic changes accompanying the disease, as well as anesthetic agents available for use. The authors discuss selection of appropriate anesthetic drugs, perioperative management considerations, pharmacologic support, intraoperative monitoring and postoperative pain management.     

Anesthetic management of a horse with traumatic pneumothorax

A traumatic pneumothorax and severe hemorrhage were present in a mare with a large thoracic wall defect, lung perforation, and multiple rib fractures. General anesthesia was induced to allow surgical exploration. We describe the anesthetic technique, and discuss the management of the ventilatory, hemodynamic, and metabolic disturbances encountered.     

Anesthetic management of ostriches.

We evaluated and characterized several anesthetic induction protocols used to facilitate intubation and anesthetic maintenance with isoflurane in 7 adult ostriches and 1 juvenile ostrich. Induction protocols included IV administration of zolazepam/tiletamine, IV administration of diazepam/ketamine with and without xylazine, IV administration of xylazine/ketamine, IM administration of carfentanil or xylazine/carfentanil, and mask induction with isoflurane. General anesthesia was maintained with isoflurane in 100% oxygen for various procedures, including proventriculotomy (6 birds), tibial (1 bird) or mandibular (1 bird) fracture repair, and drainage of an iatrogenic hematoma (1 bird). Heart rate and respiratory rate varied greatly among birds. The arterial blood pressure values recorded from 6 of the birds during maintenance of general anesthesia were higher than values recorded for most mammalian species, but were comparable to values reported for awake chickens and turkeys.     

Anesthetic management of ruminants and swine with selected pathophysiologic alterations

Surgical diseases induce pathophysiologic alterations in ruminants and swine that are often of critical importance in the perioperative period. Circulation and ventilation may be severely compromised. Alterations in acid-base balance, fluids, and electrolytes should be anticipated, identified, and corrected. Also discussed is the selection of appropriate anesthetic techniques and supportive therapy based upon the patient's physiologic status and surgical requirements.     

Anesthetic management in feline renal transplantation

Objective To document perioperative and anesthetic management of 30 feline renal transplant recipients (1996–1998). Study design Retrospective clinical study. Animals Thirty adult cats in end‐stage renal failure that underwent heterotopic renal transplantation. Materials and methods The medical records were reviewed from 30 feline heterotopic renal transplant recipients. Cases were included only if they had been treated for hypertension using a beta‐adrenergic antagonist, a calcium channel blocker or hemodialysis. Data regarding signalment, preoperative management, surgical technique, type and doses of anesthetics administered, perioperative hemodynamics and intra‐ and postoperative complications, postoperative analgesia, morbidity and early mortality were recorded. Data were expressed as mean ± SD. Results Preanesthetic medication included a combination of an anticholinergic and an opioid (oxymorphone). Anesthesia induction was performed mostly with isoflurane and oxygen delivered by mask. Anesthesia maintenance was primarily achieved with isoflurane in 100% oxygen. Nitrous oxide was often used as part of the anesthetic technique. The mean duration of anesthesia was 4.6 hours ± 27 minutes. The mean renal allograft ischemic time was 60 minutes. During the anesthetic period, the majority of the recipient cats received either fresh whole blood (FWB) (N = 25, 83%), cross‐matched packed red blood cells (PRBC) (N = 3, 10%) or fresh frozen plasma (FFP) (N = 2, 7%) combined with a balanced electrolyte solution. Blood products administered averaged 63 ± 34 mL and crystalloid 94 ± 62 mL. The most common treated intraoperative complications were hypotension (N = 14, 47%), hypothermia (N = 13, 43%), metabolic acidosis (N = 11, 37%), hypocalcemia (N = 5, 17%), hypoglycemia (N = 4, 13%), hypertension (N = 2, 7%), bradycardia (N = 1, 3%), and ventricular premature contractions (N = 1, 3%). All cats received opioid analgesics postoperatively. Complications observed in the first 24 hours postoperatively were hypertension (N = 20, 67%), hematuria (N = 14, 47%), electrolyte disturbances (N = 9, 30%), temperature imbalances (N = 5, 17%), decreased PCV requiring blood transfusion (N = 5, 17%), decreased perfusion of a foot associated with external iliac anastomosis technique (N = 5, 17%), seizures associated with hypertension (N = 3, 10%), uroabdomen (N = 2, 7%), acute graft rejection (N = 1, 3%) and, corneal ulceration (N = 1, 3%). Survival rates in the perioperative period were 100, 96.7, and 93.4% intraoperatively, at 24 hours, and 7 days following surgery. Conclusion Successful anesthesia can be performed in critically ill renal transplant recipients. However, for optimal graft function and patient survival, normothermia, normovolemia, normotension, and normal acid–base and electrolyte balance should be carefully maintained. Successful anesthetic management requires understanding of the pathophysiology of end‐stage renal disease and the maintenance of homeostasis during the different stages of the perioperative period.     

Anesthetic management with sevoflurane and oxygen for orthopedic surgeries in racehorses

Eighty-five thoroughbred racehorses with various types of fracture were subjected to arthroscopic surgery (44 horses) or internal fixation (41 horses) under sevoflurane anesthesia. The mean end-tidal sevoflurane concentration during anesthesia ranged from 2.5 to 2.8%. PaCO2 was maintained between 50 and 65 mmHg by controlled ventilation. The mean arterial blood pressure was maintained above 65 mmHg by infusion of dobutamine and fluids, however, heart rate significantly increased with time. Recovery from anesthesia was calm and smooth in almost all cases. No apparent complication was observed during and after anesthesia in all cases. Therefore, sevoflurane anesthesia is considered to be safe and useful for orthopedic surgery in racehorses.     

Fluid resuscitation and the trauma patient.

Traumatic shock can result from one or more of the following: hypovolemia, increased capillary permeability and vasodilatation, impaired myocardial contractility or dysfunction, blood loss, and cardiovascular obstruction. Animals with traumatic injuries are less tolerant of sudden increases in hydrostatic pressure, which can exacerbate fluid leakage into damaged tissues and disrupt blood clots. Pain amplifies the shock response, and analgesic therapy is always recommended in the trauma patient. Therapy must be individualized and monitored closely.     

Diseases of the thorax

Diagnostic ultrasound is an important adjunct to existing methods in the diagnosis of thoracic disease in the horse. This article discusses scanning techniques, anatomy of the thoracic cavity, and how diagnosis of pleural effusion, pulmonary abscessation, pneumothorax, and vegetative endocarditis may be facilitated by ultrasound.     

Cesarean section. Anesthetic management and surgical technique

Cesarean section can be an elective procedure but more often it is an emergency procedure that is made necessary because of dystocia. A successful outcome for both the maternal and fetal patients is primarily dependent on a thorough understanding of the physiologic alterations during normal and abnormal pregnancy and parturition. A complete history and physical examination are necessary for assessment of the dam and planning of fluid therapy and anesthetic technique. Timely coordination of presurgical preparation, anesthesia, and the surgical procedure is crucial. Because little documentation exists to prove that any one anesthetic protocol is best, this article will stress the basic principles of obstetrical anesthesia and patient management.