Comparison of arterial and venous whole blood clot initiation, formation, and strength by thromboelastography in anesthetized swine.

Thromboelastography (TEG) analysis was used to determine if differences exist between venous and arterial samples in anesthetized swine, using identical sampling techniques for each of the samples. We hypothesized that TEG parameters would not differ between native whole blood venous and arterial samples. Thirty male Landrace swines were included in the study. Both the femoral artery and vein were catheterized using standard cut-down techniques and with identically sized catheters to rule out any catheter size effects on the results. Standard TEG parameters for native whole venous and arterial blood samples (r, K, α, MA, G, and coagulation index) were measured or calculated, and t-test or Mann-Whitney rank-sum test used for comparison when appropriate. Significant differences were detected for r (venous < arterial), K (venous < arterial), α (venous > arterial), and coagulation index (venous > arterial) TEG parameters. No significant differences were measured for MA or G. These differences are important, especially when temporal changes in TEG are utilized to monitor patient stability and fluid therapy protocols using trends in coagulation properties. Taken together, these results suggest that clots are more likely to form at a faster rate in venous samples compared to arterial samples, but the overall clot strength does not differ. Therefore, if TEG analysis is being used to monitor coagulation profiles in a patient, care should be taken to use the same site and technique if results are to be used for comparative purposes.

Successful treatment of hyperkalaemic periodic paralysis in a horse during isoflurane anaesthesia.

HISTORY: A 3-year-old, 400 kg, gelding Quarter Horse was presented for investigation of epistaxis. PHYSICAL EXAMINATION: The horse was bright, alert and responsive with rectal temperature, heart rate and respiration rate within normal limits. MANAGEMENT: During a second general anaesthetic for surgical treatment of guttural pouch mycosis by balloon-tipped catheter occlusion of the right major palatine artery and ligation of the right external carotid artery, signs consistent with hyperkalaemic periodic paralysis (HYPP) were exhibited. These included concurrent hyperkalaemia, hypercapnoea, sinus tachycardia, and muscle fasciculations in the presence of normothermia. Stress associated with an acute haemorrhage pre-operatively, and intra-operative hypercapnoea may have precipitated the episode. There were no signs of HYPP during a general anaesthetic, 1 week earlier, when an initial attempt at surgical treatment of guttural pouch mycosis was performed. Treatment consisted of fluid therapy and administration of calcium gluconate (0.1-0.2 mg kg(-1) minute(-1)), dextrose 5% (5 mL kg(-1) hour(-1)) and insulin (0.05 IU kg(-1)). Treatment resulted in the resolution of clinical signs and an uneventful recovery. FOLLOW-UP: The diagnosis of HYPP was confirmed by DNA analysis post-operatively. CONCLUSIONS: Clinical cases of intra-operative HYPP can present despite a previous history of uneventful general anaesthesia. Rapid diagnosis and treatment can result in the successful management of HYPP. This report documents an unusual presentation of HYPP, a disease that remains present in the Quarter Horse population.

Physiologic effects of nasal oxygen or medical air administered prior to and during carfentanil-xylazine anesthesia in North American elk (Cervus canadensis manitobensis).

This study compared the physiologic effects of carfentanil-xylazine anesthesia in elk administered nasal oxygen or medical air. Eight female 5 +/- 2-yr-old (mean +/- SD) captive elk (Cervus canadensis manitobensis) weighing 245 +/- 20 kg and habituated to chute restraint were studied in a randomized crossover. Nasal insufflation of oxygen or medical air (10 L/min) was provided prior to and throughout anesthesia. Baseline data were collected before i.m. injection of carfentanil (10 microg/kg) and xylazine (0.2 mg/kg). Arterial blood gases (PaO2 and PaCO2), arterial blood pressure, heart and respiratory rate, and observations of muscle rigidity and movement were collected every 3 min for 30 min. Drugs were antagonized at 30 min with i.m. naltrexone (1 mg/kg) and tolazoline (2 mg/kg). Induction and recovery were significantly faster (mean +/- SD) in elk receiving oxygen (208 +/- 39 and 333 +/- 63 sec, respectively), vs. medical air (306 +/- 84 and 532 +/- 201 sec). Elk receiving oxygen had a significantly higher PaO2 and PaCO2, and significantly lower pH and heart rate. Minimum PaO2 was 75 +/- 30 mm Hg (oxygen), and 28 +/- 6 mm Hg (air). Maximum PaCO2 was 89 +/- 5 mm Hg (oxygen), and 64 +/- 4 mm Hg (air). Frequency of rigidity and movement decreased when PaO2 > or = 70 mm Hg. Animals breathing air demonstrated slower inductions and recoveries, severe hypoxemia, and increased rigidity and movement. Oxygen administration reduced hypoxemia and improved anesthesia quality, but caused prolonged periods of apnea, and moderate to severe hypercarbia and respiratory acidosis.