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Pupil reactivity can be used to evaluate central nervous system function and can be measured using a quantitative pupillometer. However, whether anesthetic agents affect the accuracy of the technique remains unclear. We examined the effects of anesthetic agents on pupillary reactivity. Thirty-five patients scheduled for breast or thyroid surgery were enrolled in the study. Patients were divided into four groups based on the technique used to maintain anesthesia: a sevoflurane-remifentanil (SEV/REM) group, a sevoflurane (SEV) group, a desflurane-remifentanil (DES/REM) group, and a propofol-remifentanil (PRO/REM) group. We measured maximum resting pupil size (MAX), reduction pupil size ratio (%CH), latency duration (LAT) and neurological pupil index (NPi). A marked reduction in MAX and %CH compared with baseline was observed in all groups, but LAT was unchanged during surgery. NPi reduced within the first hour of surgery in the SEV/REM, SEV, and DES/REM groups, but was not significantly different in the PRO/REM group. Compared with the PRO/REM group, mean %CH and NPi in patients anesthetized with SEV/REM, SEV or DES/REM were markedly lower at 1 h after surgery had commenced. There was no correlation between NPi and bispectral index. Fentanyl given alone decreased pupil size and %CH in light reflex, but did not change the NPi. NPi was decreased by inhalational anesthesia not but intravenous anesthesia. The difference in pupil reactivity between inhalational anesthetic and propofol may indicate differences in the alteration of midbrain reflexs in patients under inhalational or intravenous anesthesia.

Cannulation of the internal jugular vein (IJV) under ultrasound guidance can reduce complications, such as common carotid artery (CCA) puncture, accidental vertebral artery (VA) puncture. However, these complications still occur, especially in pediatric patients probably due to anatomical predisposition of VA. This study compared differences in anatomical location of VA and IJV between pediatric and adult patients. Children with body weight <20 kg (n = 16) and adults who required central venous or pulmonary arterial pressure monitoring (n = 21) were enrolled. After induction of general anesthesia and tracheal intubation, patients were positioned for IJV cannulation. Images of the right CCA, IJV and VA were recorded by ultrasonography. The size of each vessel, anatomical relationship of other vessels, distance between vessels and between each vessel and skin were measured. The size of VA relative to IJV was significantly larger in children than in adults (14 vs 7 %, P < 0.001). The absolute and relative distance between IJV and VA were significantly shorter in children than those in adults (P < 0.01). The anatomical relationships between IJV and CCA and that between IJV and VA were not different between children and adults. In children, VA was relatively larger and located closer to IJV than adults. The results call for careful attention to the position of VA during ultrasound-guided IJV cannulation especially in children.