Rabbit model for septic shock using bacterial strain isolated from patient with sepsis

Aravindhan, V (2020) Rabbit model for septic shock using bacterial strain isolated from patient with sepsis. Masters thesis, Christian Medical College, Vellore.

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Abstract

BACKGROUND: Septic shock is the leading cause of non-coronary deaths in ICU. Not only in adults in neonates has it still remained the dominant killer. Still the exact pathophysiology of sepsis related death is not fully explored. AIM OF THE STUDY: To create an animal model of septic shock in rabbits using bacterial strains isolated from patients. OBJECTIVES: 1. To standardize the rabbit model of septic shock by injecting the correct concentration of bacterial strains isolated from patients. 2. To study the effect of Nor Adrenaline in the above septic shock induced rabbit. 3. To study the effect of Phentolamine in the above septic shock induced rabbit. METHOD: New Zealand white rabbits (NWR) were randomly selected from animal house with weight of around 2.5–3 kgs .The animals were anaesthetized with intramuscular injection of ketamine (35 mg per kg body weight) and xylazine (5 mg per kg body weight). ECG leads and respiratory belt were placed and connected to the CMC data acquisition system. The dorsal aspect of the ears were shaved, draped, painted and intravenous catheter was placed in situ. Maintenance dose of anaesthesia (ketamine 4ml+midazolam 6ml) was infused along with normal saline for fluid replacement at the rate of 4 ml/kg/hr. Central ear artery was cannulated and connected to a pressure transducer. The animals were observed for stabilization of the above vital parameters. Escherichia coli strain isolated from patients of septicaemia was reconstituted in 2ml of normal saline and injected intravenously into the rabbit. Changes in ECG wave rate, morphology and respiratory rate (increase/decrease) was noted. Intra-arterial blood pressure was monitored. (i) In the control group, a drop in blood pressure was expected due to onset of septic shock. The animals were monitored till death. Time duration, ◆ From injecting the bacterial culture to onset of hypotension was noted. ◆ From onset of hypotension to death was noted. (ii) In another group of animals, after the onset of hypotension, Nor Adrenaline was administered intravenously and the time duration to death was noted. (iii) In another group of animals immediately after injecting the bacterial strain Phentolamine was given intravenously, and the time duration to death was noted. RESULTS: ◆ Animals that received E.coli alone died within 136±22.19 minutes. ◆ Animals that received E.coli + NA - time to death was prolonged 354±58.67 minutes. ◆ Animals that received E Coli+ Phentolamine died earlier in 49.75±26.86 minutes. ◆ There was a combined Metabolic and Respiratory acidosis after E.coli. The metabolic acidosis was associated with significant Hyperchloremia, Anion Gap did not show a significant difference. Significant Hypernatremia was seen. ◆ Mean Arterial Pressure increased in the group that received E Coli + Noradrenaline compared to the group that received E Coli + Phentolamine. CONCLUSION: 1. Effective Rabbit model of Escherichia Coli septic shock is developed to study the pathophysiology of septic shock related deaths. 2. Response to known intervention were as expected a. Alpha agonist increases MAP thus delaying death in septic shock. b. Alpha antagonist along with the additive effect of Escherichia Coli hastened death in septic shock. 3. The model can be extended using other live strains of bacteria.

Item Type: Thesis (Masters)
Additional Information: 201715351
Uncontrolled Keywords: Septic shock, Escherichia Coli, Alpha agonist, Alpha antagonist.
Subjects: MEDICAL > Physiology
Depositing User: Subramani R
Date Deposited: 30 Jan 2021 17:14
Last Modified: 01 Mar 2021 02:35
URI: http://repository-tnmgrmu.ac.in/id/eprint/13501

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