Measurement of the nociceptive balance by Analgesia Nociception Index and Surgical Pleth Index during sevoflurane-remifentanil anesthesia.

BACKGROUND: Evaluation of the nociception-anti-nociception balance during anesthesia is still challenging and routinely based on clinical criteria such as movement or vegetative response. Recently, the Analgesia Nociception Index (ANI) derived from heart rate variability and the Surgical Pleth Index (SPI) derived from photoplethysmographic signal were introduced for quantification of the analgesic component of anesthesia. METHODS: After obtaining informed consent, we studied twenty-four patients (ASA I-II) scheduled for elective surgery during induction of anesthesia with sevoflurane and a stepwise increase of remifentanil effect site concentrations. Insertion of a laryngeal mask, tetanic stimulations as well as tracheal intubation were studied as nociceptive events. RESULTS: A total of 120 events were analysed. Both ANI and SPI enabled consistent detection of nociceptive events by significant changes (∆). Further, ∆ANI and ∆SPI significantly indicated patient's movement after tetanic stimulation with a prediction probability of 0.74 and 0.84. CONCLUSION: Non-invasive monitoring of ANI and SPI reflected nociceptive stimulation during sevoflurane-remifentanil anesthesia and therefore may indicate the nociception - anti-nociception balance. Whether guidance of anesthesia by these variables will improve anesthesia care during surgery needs to be further evaluated.

Airway management in pediatric patients using the Glidescope Cobalt®: a feasibility study.

BACKGROUND: Video laryngoscopes are claimed to improve airway management. Several studies showed an equal or better glottic view using the Glidescope® compared with direct laryngoscopy in adults and in paediatric patients. Many case reports also described successful intubation in patients with a difficult airway. The Glidescope Cobalt® is a modified Glidescope® with a disposable sheath. Data on clinical application in paediatric patients is insufficient. METHODS: Twenty-four pediatric patients with a mean age of 27 months [range, 1-142] undergoing general anesthesia were included into this feasibility study. Cormack and Lehane grade was evaluated using a Macintosh blade. Tracheal intubation was performed using the Glidescope Cobalt®. Number of attempts, time to intubation, Cormack and Lehane (C&L) grade and a subjective score were noted for both a resident and an attending anesthesiologist. RESULTS: With the Glidescope Cobalt® the C&L grade improved in all patients with grade 2 or 3 to 1 and deteriorated in one case from C&L grade 1 to 2. The C&L grade remained unchanged in 15 patients (62.5%). C&L grades between resident and attending anesthesiologist were equal. Tracheal intubation was successful in 92% with a stylet-armed tube and in 8% using an unarmed tube with a Magill forceps, respectively. Time to intubation was median 50.5 [range, 22-93] seconds. CONCLUSION: The Glidescope Cobalt® presented suitable for use in children. C&L grade was significantly improved in all patients with a C&L grade of 2 or 3. Especially for educational purposes in pediatric anesthesia it provides a good view for all participants.

The effect of posture and anaesthetic technique on the surgical pleth index.

The surgical pleth index has been shown to correlate with surrogate variables of nociception during general anaesthesia, and it has been suggested to be of use as a depth of anaesthesia monitor. However, little is known about confounding factors. As the main determining variables are based on both central and peripheral autonomic regulatory mechanisms, we hypothesised that changing a patient`s posture may produce a marked effect. We studied the effects of posture change in 45 patients who were randomly assigned to receive general (n = 15) or spinal anaesthesia with (n = 15) or without sedation (n = 15), as well as 15 awake volunteers. Mean (SD) values of the surgical pleth index after adoption of the lithotomy position were reduced from 57 (22) to 21 (6) under general anaesthesia, 63 (15) to 31 (9) under spinal anaesthesia alone, and 52 (14) to 22 (8) under spinal anaesthesia with sedation (all p < 0.01). In healthy volunteers, the surgical pleth index increased from 37 (13) to 57 (11) (p < 0.01) after 30° head-up tilt and was reduced from 35 (11) to 25 (11) after head-down tilt (p < 0.05). Change in posture has a marked effect on the surgical pleth index which lasts for at least 45 min, and this must be considered when interpreting the displayed values.

Evaluation of the surgical stress index during spinal and general anaesthesia.

BACKGROUND: Although in modern anaesthesia, monitoring depth of anaesthesia and quality of neuromuscular block are routine, monitoring of analgesia still remains challenging. Recently, the surgical stress index (SSI), derived from finger photoplethysmographic signal, was introduced as a surrogate variable reflecting the nociception-antinociception balance. This study aimed at evaluating the SSI in patients undergoing regional anaesthesia either alone or combined with sedation compared with patients undergoing general anaesthesia (GA). METHODS: Seventy-one patients undergoing general (n=24) or spinal anaesthesia with (n=24) or without sedation (n=23) were included. SSI was measured the day before surgery and at defined time points during anaesthesia and surgery and also in the recovery room. SSI was compared with haemodynamic variables like heart rate and systolic arterial pressure. RESULTS: The SSI was higher in patients undergoing spinal anaesthesia [mean 65, CI (59.3-70.5)] compared with GA [48 (39.9-56.4), P<0.01], and baseline [41 (37.3-44.2), P<0.001]. During spinal anaesthesia with sedation [44 (36.2-50.9)], it was comparable with the baseline level (P>0.05). In comparison with baseline, SSI in the recovery room was higher in patients after GA [59 (48.4-67.9), P<0.025] but not after spinal anaesthesia [53 (47.6-60.1), P>0.05] or after spinal anaesthesia with sedation [54 (45.8-65.1), P>0.05]. Changes of the SSI were not reflected by changes of haemodynamic variables. CONCLUSIONS: In fully awake patients under spinal anaesthesia, the SSI does not reflect the nociception-antinociception balance. This may be due to the influence of mental stress on the sympathetic nervous system. Even light sedation attenuates these influences.