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1.
Successful anesthetic management of dogs with reduced intracranial compliance requires a knowledge of the effects of various anesthetic agents on cerebral blood flow and intracranial pressure. The major physiologic factors that influence cerebral blood flow and intracranial pressure (ICP) include the cerebrovascular autoregulatory mechanism, intracranial compliance, blood pressure, and the partial pressure of carbon dioxide. Intravenous and inhalation anesthetic agents alter cerebral blood flow and intracranial pressure in the dog. These alterations can have profound effects in dogs with reduced intracranial compliance, necessitating proper anesthetic management. Suggested guidelines for neuroleptanesthetic and inhalation anesthesia regimens in dogs with reduced intracranial compliance include thorough presurgical evaluation, minimal patient stress during induction, use of an anesthetic protocol that minimizes ICP effects, and hyperventilation to maintain a Pco2 within a range of 25 to 35 mm Hg.  相似文献   

2.
Anesthetic management of the head trauma patient   总被引：1，自引：0，他引：1  
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.  相似文献   

3.
OBJECTIVE: To develop and compare 3 techniques for retrobulbar injection of local anesthetic agents for ocular surgery and analgesia in dogs. DESIGN: Prospective study. ANIMALS: 17 dogs (including 9 cadavers). PROCEDURES: Inferior-temporal palpebral (ITP), perimandibular, and combined superior-inferior peribulbar injection techniques were compared by assessing the distribution of latex after injection into the orbits of 5 canine cadavers; magnetic resonance imaging (MRI) evaluation of the distribution of contrast agent after injection in the retrobulbar space of 4 canine cadavers; and assessment of the efficacy and MRI evaluation of the anatomic distribution of injections of a lidocainecontrast agent mixture in 4 anesthetized, nonrecovery dogs. By use of the preferred technique (ITP), the ocular effects of lidocaine anesthesia were evaluated in 4 dogs; during a 2-week period after treatment, dogs underwent ophthalmic examination, Schirmer tear testing (STT), intraocular pressure (IOP) measurement, and Cochet-Bonnet esthesiometry. RESULTS: Of the 3 techniques, the ITP technique was the preferred method for retrobulbar administration of anesthetic agent in dogs because it was efficacious (pupil dilation and central rotation of the globe achieved in all eyes), easiest to perform, and provided thorough coverage of the intraconal retrobulbar space without complication. During the 2-week follow-up period, the ITP injection did not significantly affect STT, IOP, or Cochet-Bonnet esthesiometry values in dogs. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, retrobulbar administration of anesthetic agents via the ITP technique is a potential alternative to systemic administration of neuromuscular blocking agents for ophthalmic surgery and provides the additional benefit of local ocular analgesia.  相似文献   

4.
Pet rabbits frequently become stressed when handled and may require sedation or chemical immobilization for procedures such as blood collection, IV catheter placement, radiography, deep ear cleaning, and dentistry. Common surgical procedures requiring general anesthesia include spay, castration, gastrotomy, cystotomy, and orthopedic procedures. Rabbits may be difficult to safely sedate or anesthetize. Individual rabbits may have varying sensitivity to the depressant effects of anesthetics. The apparent sensitivity of the rabbit's respiratory center to anesthetic drugs and the narrow range between anesthetic and toxic doses in this species add to the unpredictable character of rabbit anesthesia. Furthermore, mortality following anesthesia and surgery in sick rabbits is common. Strategically, safe anesthesia of rabbits must include the planning of procedures so that anesthetic time is minimized. Clinicians must be on guard for individual variation in response to drugs. Minimizing the use of cardiovascular depressant agents, use of agents with a high therapeutic index, and careful titration of doses to effect, along with thorough cardiorespiratory monitoring, will permit attainment of appropriate anesthetic depth with the widest margin of safety. This article presents several injectable and inhalant anesthetic protocols that may assist in effective management of many types of rabbit patient.  相似文献   

5.
Current research on the development of new neuromuscular blocking agents is directed towards producing agents that have a rapid onset of action and predictable duration of action and recovery times, with minimal hemodynamic effects. For the veterinary practitioner, these newer agents should be considered when muscle relaxation is required for certain surgical procedures. Care must be taken to monitor paralyzed patients appropriately to ensure adequate ventilation and anesthetic depth. Vigilant monitoring should exist during the recovery period for the development of muscle weakness from residual blockade and the ability to reverse the effects of neuromuscular blockade. The use of neuromuscular blocking agents in veterinary patients should continue to increase as newer drugs and better monitoring techniques are developed.  相似文献   

6.
With many modern anesthetic drugs and combinations, the traditional signs of anesthetic depth as a continuum of increasing depression are often incorrect. The concept of "adequate anesthetic depth" is difficult to define because it depends on the end points chosen to define "adequate." Because both central nervous system excitant and depressant drugs can induce a stage of anesthesia, it is vital that those using these agents be keenly aware of the specific type of anesthetic agent or agents being used, and their effects.  相似文献   

7.
Small animal patients must often undergo veterinary procedures that are painful or distressful, for which judicious use of sedatives or other agents with anesthetic or analgesic properties can be useful. If the degree of sedation is profound enough, such "chemical restraint" may be employed to provide immobilization for radiographs or minor surgical procedures. The choice of agents to be used will depend upon the physiologic state and cooperative nature of the patient and the desired endpoint, ie, anxiolysis versus deep sedation with analgesia. This report discusses important features of patient assessment, preparation, equipment needs, consideration of the types of procedures for which sedation is useful, and recovery considerations. A brief review is included of the useful effects and contraindications for the various agents employed, and doses for each are listed. Algorithms are presented for a given category of patient, leading the practitioner through a decision making strategy to arrive at examples of sedation or chemical restraint protocols that are commonly found to be effective by the author.  相似文献   

8.
Medetomidine is a relatively new sedative analgesic drug that is approved for use in dogs in Canada. It is the most potent alpha2-adrenoreceptor available for clinical use in veterinary medicine and stimulates receptors centrally to produce dose-dependent sedation and analgesia. Significant dose sparing properties occur when medetomidine is combined with other anesthetic agents correlating with the high affinity of this drug to the alpha2-adrenoreceptor. Hypoventilation occurs with medetomidine sedation in dogs; however, respiratory depression becomes most significant when given in combination with other sedative or injectable agents. The typical negative cardiovascular effects produced with other alpha2-agonists (bradycardia, bradyarrhythmias, a reduction in cardiac output, hypertension +/- hypotension) are also produced with medetomidine, warranting precautions when it is used and necessitating appropriate patient selection (young, middle-aged healthy animals). While hypotension may occur, sedative doses of medetomidine typically raise the blood pressure, due to the effect on peripheral alpha2-adrenoreceptors. Anticholinergic premedication has been recommended with alpha2-agonists to prevent bradyarrhythmias and, potentially, the reduction in cardiac output produced by these agents; however, current research does not demonstrate a clear improvement in cardiovascular function. Negatively, the anticholinergic induced increase in heart rate potentiates the alpha2-agonist mediated hypertension and may increase myocardial oxygen tension, demand, and workload. Overall, reversal with the specific antagonist atipamezole is recommended when significant cardiorespiratory complications occur. Other physiological effects of medetomidine sedation include; vomiting, increased urine volumes, changes to endocrine function and uterine activity, decreased intestinal motility, decreased intraocular pressure and potentially hypothermia, muscle twitching, and cyanosis. Decreased doses of medetomidine, compared with the recommended label dose, should be considered in combination with other sedatives to enhance sedation and analgesia and lower the duration and potential severity of the negative cardiovascular side effects. The literature was searched in Pubmed, Medline, Agricola, CAB direct, and Biological Sciences.  相似文献   

9.
Isoflurane anesthesia is commonly used in ferrets for routine examinations and diagnostics. Sevoflurane is now being used as well, but there have been no studies to date directly comparing these agents in domestic ferrets. A prospective study was designed to evaluate the quality and speed of anesthetic induction and recovery using isoflurane and sevoflurane in ferrets. In addition effects on heart rate, blood pressure and packed cell volume were also recorded. No significant differences were noted between anesthetic agents.  相似文献   

10.
Neuromuscular blocking agents, although not commonly used in veterinary practice, should be considered when muscle relaxation is needed to facilitate surgical exposure and minimize tissue trauma. These drugs should be administered only once respiration has been controlled and anesthetic agents have been administered to induce unconsciousness and analgesia. Following administration of neuromuscular blocking drugs, neuromuscular and cardiovascular function must be monitored.  相似文献   

11.
Organ toxicity from local anesthetic agents is rare. This makes these agents an attractive option in the high-risk patient. Complications associated with local anesthetics are related to overdosage. Overdosage with local anesthetic agents administered epidurally may cause motor paralysis and hind-limb weakness. Systemic signs of local anesthetic overdosage include changes in central nervous system activity (excitement or depression), muscle tremors, and hypotension. Because the dose required to produce these effects in the horse is high (12 mg/kg), this complication is uncommon. Few side effects and low cost justify the use of local anesthetic techniques in equine practice.  相似文献   

12.
Several unique pharmacologic and physiologic factors must be considered when attempting to anesthetize premature or neonatal foals. Juvenile foals are similar to adults in their physiology and metabolism. Anesthetic drug and protocol selection should reflect the differences between these two age groups. Neonates are best anesthetized using an inhalation technique, whereas older foals can be safely anesthetized with either parenteral or inhalation anesthetic agents. Careful monitoring is absolutely essential when anesthetizing foals. The clinician should plan to routinely administer fluids and measure electrolyte levels. A basic plan and knowledge of the methods and agents used to treat hypovolemia, severe cardiopulmonary collapse, and life-threatening arrhythmias can result in survival of many critically ill foals.  相似文献   

13.
In conclusion, vigilant supportive care is necessary to prevent morbidity and death in the anesthetized horse. Because some of the equipment and drugs are specialized and the consequences of some postanesthetic complications are severe, availability of those items must be confirmed prior to anesthesia. Proper positioning and padding will help to reduce the incidence of postanesthetic myopathy-neuropathy syndrome in these large patients. Adequate tissue perfusion is important and can be achieved by controlling anesthetic depth, increasing intravascular volume with fluid administration, and by administering sympathomimetic agents.  相似文献   

14.
OBJECTIVE: To compare intraocular pressure (IOP) measurements obtained by recently introduced rebound tonometer (ICare) and the well-known applanation tonometer Tonopen XL in normal canine eyes. METHODS: In a prospective, randomized, single-center study, IOP measurements by ICare and Tonopen XL tonometers were compared in 160 nonpathologic canine eyes (80 dogs). Complete slit-lamp biomicroscopy and indirect ophthalmoscopy were performed on each dog. Rebound tonometry was performed first and immediately after topical anesthetic drops were instilled in both eyes. One minute after the application of the topical anesthetic, applanation tonometry was performed in both eyes. The intraocular pressures obtained by use of both techniques were compared by statistical analysis. RESULTS: The mean IOP readings were 9.158 mmHg (SD 3.471 mmHg) for the ICare tonometer (x) and 11.053 mmHg (SD 3.451 mmHg) for the Tonopen XL readings (y). The mean difference in intraocular pressures (-1.905 mmHg) was within clinically acceptable limits. The correlation coefficient (r2) of the relationship within both tonometers was r2=0.7477. The corresponding linear regression between the tonometers readings was y=0.6662x+4.942. CONCLUSIONS: Intraocular pressures obtained with the ICare rebound tonometer were concordant with the IOP readings obtained by applanation Tonopen XL, but ICare values were significantly (P<0.0001) lower. Rebound tonometry could be an appropriate tonometry method for routine clinical use after its calibration for canine eyes.  相似文献   

15.
Early spay-neuter is ovariohysterectomy or castration of puppies or kittens 6 to 14 weeks of age. Pediatric animals may have an enhanced response to relatively low doses of anesthetic agents. Animals should be fasted no more than 3 to 4 hours before surgery to prevent hypoglycemia, and hypothermia should be avoided. Heart and respiratory rates must be monitored carefully throughout anesthesia. Pediatric gonadectomy surgeries are quick with minimal bleeding. Anesthetic recovery is rapid. No significant short-term or long-term effects have been reported. Prepuberal gonadectomy is most useful for humane organizations and conscientious breeders wishing to preclude reproduction of pet dogs and cats while placing animals at a young enough age to optimize socialization and training.  相似文献   

16.
OBJECTIVE: To determine the minimum anesthetic concentration for sevoflurane and effects of various multiples of minimum anesthetic concentration on arterial pressure and heart rate during controlled ventilation in chickens. STUDY DESIGN: Prospective experimental study. ANIMALS: Seven healthy chickens, 6 to 8 months old, weighing 1.6 to 3.4 kg. METHODS: A rebreathing, semiclosed anesthetic circuit was used. Anesthesia was induced by mask with sevoflurane in oxygen. Each chicken was endotracheally intubated, then controlled ventilation was started and the end-tidal CO2 partial pressure was maintained at 30 to 40 mm Hg. Body temperature was maintained at 39.5 degrees to 41.0 degrees C. The inspired and end-tidal sevoflurane concentration were monitored with a multigas monitor. Minimum anesthetic concentration was determined as the minimal end-tidal sevoflurane concentration which prevented gross purposeful movement in response to clamping a toe for 1 minute. After the determination, the cardiovascular effects of sevoflurane at 1.0, 1.5, and 2.0 times the minimum anesthetic concentration were determined. RESULTS: The minimum anesthetic concentration for sevoflurane was 2.21% + 0.32% (mean +/- SD). Mean arterial pressure and heart rate at minimum anesthetic concentration were 84 +/- 13 mm Hg and 150 +/- 58 beats/min, respectively. There was a dose-dependent decrease in arterial pressure. The heart rate did not change significantly over the range 1 to 2 x minimum anesthetic concentration. No cardiac arrhythmias developed throughout the experiments. CONCLUSIONS AND CLINICAL RELEVANCE: The minimum anesthetic concentration for sevoflurane in chickens was within the range of minimum alveolar concentration reported in mammals. When the concentration of sevoflurane is increased during controlled ventilation in chickens, decrease in arterial pressure should be expected.  相似文献   

17.
Ultrashort barbiturates are not ideal injectable anesthetic agents, and new agents continue to be released as investigators pursue the goal of finding a more ideal agent. Of the new injectable agents discussed, propofol seems to be the most promising drug. Propofol should find a place in veterinary practice as an outpatient anesthetic agent because it has a rapid, smooth, and complete recovery even after repeated or continuous administration. Midazolam does not induce anesthesia in healthy, small animals and, as such, can only be used in combination with other injectable agents, such as ketamine or the thiobarbiturates. In our practice, Telazol has found a place in the anesthetic management of feral cats and aggressive dogs, where it is used for heavy sedation or to induce anesthesia. The role of flumazenil, as a reversal agent, in veterinary practice remains to be determined; however, the role in small domestic animals is unlikely to be significant.  相似文献   

18.
Anesthesia for patients with head trauma.   总被引：1，自引：0，他引：1  
Patients undergoing anesthesia soon after head trauma are at great risk for further neural damage during the anesthetic, especially if the head injury is severe or the anesthetic technique is suboptimal. Secondary complications of the anesthetic that are often lethal include hypoventilation, increases in ICP, airway obstruction, and brain-stem herniation. Anesthetic management of patients with head injury must include intravenous induction with barbiturates or narcotics, smooth endotracheal intubation, controlled ventilation with oxygen, and minimal amounts of inhalational agents. It is important to position the patient so that jugular veins are not occluded, in about 10 degrees head up position, and to avoid inducing patient coughing and straining. Recovery from anesthesia should be quiet and rapid, with the maintenance of a clear airway and the use of as little depressant medication post-operatively as possible. Oxygen should be provided.  相似文献   

19.
Equilibration between delivered and effect site anesthetic partial pressure is slow in frogs. The use of less soluble agents or overpressure delivery may speed equilibration. Ten Northern leopard frogs were exposed to 3-4 constant concentrations of halothane, isoflurane or desflurane and their motor response to noxious electrical stimulation of the forelimb evaluated every 30 minutes until a stable proportion of frogs were immobile. Each frog received each anesthetic and concentration in random order and allowed at least 14 hours to recover between anesthetic exposures. An overpressure technique based upon the kinetics in the first study was then tested with 4 concentrations of desflurane. For halothane, isoflurane and desflurane respectively; the proportion of frogs immobile in response to stimulus became stable after 510, 480 and 180 minutes, and ED50 values were 1.36, 1.67 and 6.78 % atm. Desflurane ED50 delivered by overpressure was not significantly different at 6.85 % atm. Halothane, isoflurane and desflurane are effective general anesthetics in frogs with potencies similar to those reported in mammals. The time required for anesthetic equilibration is fastest with desflurane and can be hastened further by initial delivery of higher partial pressures.  相似文献   

20.
The effects of different arterial carbon dioxide tensions (PaCO2) on cerebrospinal fluid pressure (CSFP) and intraocular pressure (IOP) were studied in 6 male halothane-anesthetized horses positioned in left lateral recumbency. Steady-state anesthetic conditions (1.06% end-tidal halothane concentration) commenced 60 minutes following anesthetic induction with only halothane in oxygen. During atracurium neuromuscular blockade, horses were ventilated, and respiratory rate and peak inspiratory airway pressure were maintained within narrow limits. The CSFP and IOP were measured at 3 different levels of PaCO2 (approx 40, 60, and 80 mm of Hg). The PaCO2 sequence in each horse was determined from a type of switchback design with the initial PaCO2 (period 1), established 30 minutes after the commencement of steady-state anesthesia, being repeated in the middle (period 3) and again at the end (period 5) of the experiment. Measurements taken from the middle 3 periods (2, 3, and 4) would form a Latin square design replicated twice. The interval between each period was approximately 45 minutes. Data from periods 2, 3, and 4 indicated that CSFP (P less than 0.05) and mean systemic arterial pressure increased significantly (P less than 0.05) with high PaCO2. Mean central venous pressure, heart rate, and IOP did not change significantly during these same conditions. Measurements taken during periods 1, 3, and 5 were compared to assess the time-related responses to anesthesia and showed a significant increase in CSFP, a significant decrease in mean central venous pressure, and a small (but not statistically significant) increase in mean systemic arterial pressure.  相似文献   

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