Paediatric caudal anaesthesia: Difference between revisions

Early neurosensory warning symptoms of LA systemic toxicity are concealed by general anaesthesia. Halogenated anaesthetic agents worsen LA systemic toxicity and can also blunt the cardiovascular signs of an intravenous epinephrine test dose injection. Aspiration tests to elicit blood reflux are not very sensitive, particularly in infants. A test dose of epinephrine 0.5mcg.kg-1 (administered as 0.1ml.kg-1 lidocaine with epinephrine 1 in 200 000) allows detection of intravenous injection with sensitivity and specificity close to 100%, under halogenated anaesthesia. [[File:Caudal Positive test ECG.jpg|thumb|'''Figure 9.''' T-wave amplitude change after intravascular injection of a local anaesthetic agent]] Warning symptoms are cardiac frequency modification (an increase or decrease by 10 beats per minute), increased in blood pressure (up to 15mmHg), or T-wave amplitude change in the 60 to 90 second period after injection (Figure 9). <ref name=":1">Kozek-Langenecker SA, Marhofer P, Jonas K, Macik T, Urak G, Semsroth M. Cardiovascular criteria for epidural test dosing in sevoflurane- and halothane-anesthetized children. Anesth Analg 2000; 90: 579-83.</ref>, <ref>Tobias JD. Caudal epidural block: a review of test dosing and recognition injection in children. Anesth Analg 2001; 93: 1156-61.</ref> Slow injection of the whole LA dose under haemodynamic and ECG monitoring remains essential for patient safety.