ABSTRACT
OBJECTIVE: To determine the type of atrial fibrillation induced by use of 2 pacing protocols during fentanyl and pentobarbital anesthesia before and after administration of atropine and to determine the organization of electrical activity in the left and right atria during atrial fibrillation in German Shepherd Dogs. ANIMALS: 7 German Shepherd Dogs. PROCEDURES: Extrastimulus and pacedown protocols were performed before and after atropine administration. Monophasic action potential spectral entropy and mean dominant frequency were calculated during atrial fibrillation. RESULTS: Atrial fibrillation occurred spontaneously in 6 of 7 dogs. All 7 dogs had atrial fibrillation induced. Sustained atrial fibrillation occurred in 13 of 25 (52%) episodes induced by the extrastimulus protocol and in 2 of 12 episodes of atrial fibrillation induced by pacedown. After atropine administration, sustained atrial fibrillation did not occur, and the duration of the nonsustained atrial fibrillation (6 episodes in 2 dogs of 1 to 26 seconds) was significantly shorter than before atropine administration (25 episodes in 7 dogs of 1 to 474 seconds). The left atrium (3.67 +/- 0.08) had lower spectral entropy than the right atrium (3.81 +/- 0.03), indicating more electrical organization in the left atrium. The mean dominant frequency was higher in the left atrium in 3 dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Atrial fibrillation developed spontaneously and was induced in German Shepherd Dogs under fentanyl and pentobarbital anesthesia. Electrical activity was more organized in the left atrium than in the right atrium as judged by use of spectral entropy.
Subject(s)
Anesthetics, Intravenous/adverse effects , Arrhythmias, Cardiac/veterinary , Atrial Fibrillation/veterinary , Dog Diseases/chemically induced , Action Potentials/drug effects , Action Potentials/physiology , Anesthetics, Intravenous/administration & dosage , Animals , Arrhythmias, Cardiac/genetics , Atrial Fibrillation/chemically induced , Atropine , Dogs , Electrocardiography/veterinary , Fentanyl/administration & dosage , Fentanyl/adverse effects , Pentobarbital/administration & dosage , Pentobarbital/adverse effectsABSTRACT
This paper describes a standardization method that allows injury researchers to directly compare pedestrian hood contact points across a variety of hood sizes and geometries. To standardize hood contact locations a new coordinate system was created at the geometric center of the hood. Standardizing hood contact locations was done by turning each coordinate location into a ratio of the entire length or width of the hood. The standardized pedestrian contact locations could then be compared for various hood sizes. The standardized hood was divided into a three-by-three grid to aggregate contact points into hood regions. Data was obtained from the National Highway Traffic Safety Administration's Pedestrian Crash Data Study from 1994 to 1998. To understand injury severity with respect to pedestrian hood contact location, the injuries were narrowed to the single most severe Abreviated Injury Scale injury to the pedestrian and hood location at which that injury was sustained. Of the 97 pedestrian/vehicle cases, pedestrians received 270 injuries from 141 unique hood contact locations. After standardization, 36%, 28%, 36% of all contact points were located on the left, center and right side of the hood respectively. Vertically, 26%, 45%, 28% of contacts occurred at the front, middle, and rear regions of the hood respectively. The middle passenger side of the hood contained the most number of AIS 3+ injuries. By using real-world crash data, engineers can make evidence based decisions to decease the severity of pedestrian injuries.
