Measurement of the puncture profile and extradural pressure of cattle during extradural anaesthesia

ObjectiveTo measure the pressure profile during caudal extradural puncture and subsequent extradural anaesthesia in cattle and to investigate the presence of extradural pressure waves.Study designProspective experimental study.AnimalsEleven cattle aged 4.1 ± 2.5 years (range 0.8 to 8.8 years), with a body weight of 613 ± 162 kg (range 302–840 kg).MethodsCaudal extradural puncture was performed. To measure the extradural pressure profile, the needle was connected to an electronic pressure transducer placed at the height of the base of the tail. The pressure profile was recorded for 3 minutes following extradural puncture. Lack of resistance to injection of saline was assessed. One minute and 10 minutes after extradural anaesthesia with procaine extradural pressure was recorded. Correct extradural needle placement was assessed by clinical response.ResultsThree minutes after extradural puncture the median pressure was ?16 (range ?25 to 25) mmHg. Pressure in the extradural space 1 minute after the lack of resistance, 3 seconds after injection, and 10 minutes after injection was ?15 (?24 to 33) mmHg, 8 (?17 to 84) mmHg, and ?7 (?25 to 27) mmHg respectively. Pressure waves were visible after puncture, after lack of resistance, 3 seconds and 10 minutes after injection, in 4, 6, 8 and 7 cattle respectively. Pressure after testing lack of resistance, after the injection of local anaesthetic, as well as at the end of the measurement, period was significantly higher than baseline. All cattle showed clinical signs indicative of successful extradural needle placement.Conclusion and clinical relevance Extradural pressure was sub-atmospheric in 82% of the animals. Pressure waves were not consistently present before or after extradural injection, which limits their usefulness to confirm correct extradural needle placement. Extradural pressures increase significantly after injection of local anaesthetic solution. However, the clinical significance of the increase in extradural pressures was not clear.