Development of an Algorithm to Perform a Comprehensive Study of Autonomic Dysreflexia in Animals with High Spinal Cord Injury Using a Telemetry Device

Summary

The catheter of a telemetry device is implanted into the abdominal aorta in order to continuously collect beat-by-beat hemodynamic data from animals pre and post-high thoracic spinal cord transection. A novel JAVA software was employed to analyze hemodynamic parameters as well as frequency and intensity of spontaneous episodes of autonomic dysreflexia.

Abstract

Spinal cord injury (SCI) is a debilitating neurological condition characterized by somatic and autonomic dysfunctions. In particular, SCI above the mid-thoracic level can lead to a potentially life-threatening hypertensive condition called autonomic dysreflexia (AD) that is often triggered by noxious or non-noxious somatic or visceral stimuli below the level of injury. One of the most common triggers of AD is the distension of pelvic viscera, such as during bladder and bowel distension or evacuation. This protocol presents a novel pattern recognition algorithm developed for a JAVA platform software to study the fluctuations of cardiovascular parameters as well as the number, severity and duration of spontaneously occurring AD events. The software is able to apply a pattern recognition algorithm on hemodynamic data such as systolic blood pressure (SBP) and heart rate (HR) extracted from telemetry recordings of conscious and unrestrained animals before and after thoracic (T3) complete transection. With this software, hemodynamic parameters and episodes of AD are able to be detected and analyzed with minimal experimenter bias.

Introduction

Autonomic dysreflexia (AD) is a life-threatening emergency in individuals after acute or chronic spinal cord injury (SCI) at cervical or high-thoracic segments and is usually characterized by episodes of persistent hypertension and bradycardia¹. AD is principally caused by disruption of descending spinal pathways that usually provide input from supraspinal centers to the spinal sympathetic preganglionic neurons that control sympathetic activity and vascular tone^1-4. AD episodes are characterized by a spike in systolic blood pressure (SBP) up to 300 mmHg and if left untreated may lead to seizures, intracranial hemorrhage, myocardial infarction, an....

Protocol

Male Wistar (Hsd: WI Wistar) rats at 7 weeks of age and weighing 300-350 g were used in this experiment. All rats were maintained on a 12 hr light/dark cycle and received standard laboratory rat chow and water ad libitum. All experimental procedures conformed with the guide to the Care and Use of Experimental Animals established by the Canadian Council on Animal Care and granted ethics approval by the University of British Columbia. Surgery and animal care were conducted according to standard procedures in our laboratory (Ramsey et al. 2010)¹⁷.

1. Preparation of the Animals: Surgical Procedures

1. I....

Results

Using telemetry, arterial blood pressure is sampled at a frequency of 1,000 Hz continuously for 24 hr. An illustrative recording of arterial blood pressure (ABP) using LabChart is shown in Figure 1B. The sample ABP was monitored by a solid state pressure sensor inserted into the descending aorta. The novel JAVA platform AD Detection software is able to extract relevant SBP (mmHg) peaks (Figure 1C). We may also extract the HR (bpm) from the time interval between adjacent SBP peaks (

Discussion

The protocol describes a detailed implementation of a novel JAVA platform AD Detection software which would be combined with a telemetry device, for a long-term thorough analysis of ABP in SCI-animals (Figure 1B). This is the first software that allows for the characterization of ABP patterns to detect spontaneous AD events as they occur sporadically throughout the duration of the day. A well-characterized T3 SCI animal model can illustrate the functional capacity of the software to detect the frequ.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
11 Male Wistar Rats -Hsd-WI (250-300g)	Envigo (formerly Harlan Laboratories)	141
Lab Chart (PowerLab® Data Acquisition System)	AD Instruments
Pressure Telemeter	Millar Inc.	RP-TRM54P
Configurator	Millar Inc.	TR190
SmartPad	Millar Inc.	TR180
Isoflurane (Aerrane)	Baxter Corp.	DIN: 02225875
Enrofloxacin (Baytril)	Bayer Healthcare	DIN: 02169428
5-0 Silk Sutures	Ethicon	S182
4-0 Vicryl Subcuticular	Ethicon	J496G
Buprenorphine (Temgesic)	Reckitt Benckiser	DIN: 0281250
Bupivicaine Hydrochloride (Marcaine 0.5%)	Hospira Healthcare Corp.	DIN: 02305909
Ketoprofen (Anafen)	Merial	DIN: 02150999
Ketamine Hydrochloride (Vetalar)	Bioniche	DIN: 01989529
Dexmedetomidine Hydrochloride (Domitor)	Pfizer	DIN: 02333929
Lactated Ringer's Solution	Braun Medical Inc.	DIN: 01931636
Gelfoam #12	Pharmacia & Upjohn Company	03603-14-1
Microscissors	Fine Science Tools	15003-008
Iris Spatulae	Fine Science Tools	10094-13
10 French 35 cm Foley Catheter	Coloplast	AA6110
Dietgel®	Clear H2O, Westbrook, ME	76A
LabDiet Rodent Diet 5001	Purina Mills (PMI®)	5001
Chlorhexadine (Hibitane)	Wyeth Animal Health, Guelph, Ontario	DIN 00245097
Atipamezole Hydrochloride(Antisedan)	Orion Pharma	DIN: 02237744