Caudal epidural anesthesia in mares after bicarbonate addition to a lidocaine–epinephrine combination

A narrative review of caudal epidural anaesthesia and analgesia in horses. Part 1: Safety and efficacy of epidural drugs

“…Local anaesthetics produce nonselective sympathetic, sensory and motor nerve blockade by preventing depolarisation of the nerve membrane and conduction of nerve impulses (Robinson and Natalini 2002;Carpenter and Byron 2015). The most commonly used local anaesthetic for epidural application in horses is lidocaine 2%, which has a rapid onset (2-15 min) and produces between 1 and 3 h of sensory and motor blockade involving the coccygeal, perineal, sacral and lower lumbar regions as well as the upper region of the pelvic limbs (Olbrich and Mosing 2003;Derossi et al 2005aDerossi et al , 20082012a;2013;Sadegh and Shafiei 2008;Duarte et al 2017;Valadares et al 2017;Ghazaleh et al 2018). Mepivacaine has been reported to have a similar onset (5-30 min) and duration of action (1-3 h) to lidocaine (Skarda and Muir 1983;Skarda et al 1984;Robinson and Natalini 2002;Skarda et al 2005;Michou and Leece 2012;Carpenter and Byron 2015;Bird et al 2019).…”

“…Various other drugs have also been investigated as potential adjuvants to epidural local anaesthetics, including epinephrine, bicarbonate, magnesium sulphate and neostigmine. The addition of the vasoconstrictor epinephrine (5 µg/mL) to epidural local anaesthetics has been described to reduce systemic absorption, and thereby reduce systemic side-effects and improve the quality and duration of epidural anaesthesia (Robinson and Natalini 2002;Carpenter and Byron 2015;Duarte et al 2017). Furthermore, alkalisation of lidocaineepinephrine solution by addition of sodium bicarbonate has shown to decrease the duration of ataxia and reduce the onset of anaesthesia, without affecting the duration and extent of anaesthesia (Duarte et al 2017).…”

“…The addition of the vasoconstrictor epinephrine (5 µg/mL) to epidural local anaesthetics has been described to reduce systemic absorption, and thereby reduce systemic side-effects and improve the quality and duration of epidural anaesthesia (Robinson and Natalini 2002;Carpenter and Byron 2015;Duarte et al 2017). Furthermore, alkalisation of lidocaineepinephrine solution by addition of sodium bicarbonate has shown to decrease the duration of ataxia and reduce the onset of anaesthesia, without affecting the duration and extent of anaesthesia (Duarte et al 2017). By contrast, the addition of magnesium sulphate to lidocaine has been shown to prolong the onset of epidural anaesthesia, presumably because of the pH-lowering effect (Sadegh and Shafiei 2008).…”

“…2005a, 2008; 2012a; 2013; Sadegh and Shafiei 2008; Duarte et al . 2017; Valadares et al . 2017; Ghazaleh et al .…”

“…Furthermore, alkalisation of lidocaine–epinephrine solution by addition of sodium bicarbonate has shown to decrease the duration of ataxia and reduce the onset of anaesthesia, without affecting the duration and extent of anaesthesia (Duarte et al . 2017). By contrast, the addition of magnesium sulphate to lidocaine has been shown to prolong the onset of epidural anaesthesia, presumably because of the pH‐lowering effect (Sadegh and Shafiei 2008).…”