Predicting personalised remifentanil effect site concentration for surgical incision using the nociception level index: A prospective calibration and validation study.

BACKGROUND: Inadequate antinociception can cause haemodynamic instability. The nociception level (NOL) index measures response to noxious stimuli, but its capacity to predict optimal antinociception is unknown. OBJECTIVE: To determine if NOL index change to a tetanic stimulus in cardiac and noncardiac surgery patients could predict the required remifentanil concentration for haemodynamic stability at skin incision. DESIGN: A prospective two-phase cohort study. SETTING: University hospital. PATIENTS: Patients undergoing remifentanil-propofol target controlled infusion (TCI) anaesthesia. INTERVENTIONS: During the calibration phase, investigators evaluated the tetanic stimulus induced NOL index change under standardised TCI remifentanil-propofol anaesthesia during a no-touch period [bispectral index (BIS) between 40 and 60, NOL index under 15]. If the NOL index change was 20 or greater following tetanic stimulation, investigators repeated the tetanus at higher remifentanil concentrations until the response was blunted. Surgeons incised the skin at this remifentanil concentration. The investigators derived a prediction model and in the validation phase calculated, using the NOL response to a single tetanus, the required incision remifentanil concentration for the start of surgery. MAIN OUTCOME: Haemodynamic stability at incision [i.e. maximum heart rate (HR) < 20% increase from baseline, minimum HR (40 bpm) and mean arterial pressure (MAP) ± <20% of baseline]. RESULTS: During the calibration phase, no patient had hypertension. Two patients had a HR increase slightly greater than 20% (25.4 and 26.7%) within the first 2 min of surgery, but neither of these two patients had a HR above 76 bpm. Two patients were slightly hypotensive after incision (MAP 64 and 73 mmHg). During the validation phase, neither tachycardia nor hypotension occurred, but MAP increased to 21.5% above baseline for one patient. CONCLUSION: During a no-touch period in patients under steady-state general anaesthesia [propofol effect site concentration (Ce) required for BIS between 40 and 60], the NOL index response to a tetanic stimulus under remifentanil antinociception can be used to personalise remifentanil Ce for the start of surgery and ensure stable haemodynamics. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03324269.

Lung separation in adult thoracic anesthesia.

Thoracic anesthesia is mainly the world of OLV during anesthesia. The indications for OLV, classified as absolute or relative are more representative of the new concepts in OLV: It includes either the separation or the isolation of the lungs. Modern DLTs are most widely employed worldwide to perform OLV including the concept of one lung separation. Endobronchial blockers are a valid alternative to DLTs, and they are mandatory in the education of lung separation and in case of predicted difficult airways as they are the safest approach (with an awake intubation with an SLT through a FOB). Every general anesthesiologist should know how to insert a left-sided DLT, but he/she should also have in his technical luggage and toolbox, basic knowledge and minimal expertise with BBs, this option being considered a suitable alternative, particularly in emergency situation where the patient is already intubated and/or in case of difficult airways. One should keep in mind that extubation or re-intubation after DLT might be difficult too, and additional intubation tools are necessary for the safety conditions.

Gradual withdrawal of remifentanil delays initial post-operative analgesic demand after thyroid surgery; double-blinded, randomized controlled trial.

BACKGROUND: Mismanagement of remifentanil leads to severe side effects such as opioid-induced tolerance and hyperalgesia. Recently studies revealed an alternative withdrawal method to limit these side effects. A gradual withdrawal of remifentanil seems to be associated with less pain. The hypothesis of this double-blinded, randomized controlled trial was that a gradual withdrawal of remifentanil would be associated with less immediate post-operative pain compared to after an abrupt discontinuation of remifentanil in patients who underwent thyroid surgery. METHODS: This double-blinded, randomized controlled trial was conducted in a tertiary level hospital in Brussels (Belgium) from April until August 2017. 34 patients undergoing thyroid surgery were randomized and 29 patients completed the study. After randomization, patients undergoing thyroid surgery were allocated to two groups: one with an abrupt discontinuation of remifentanil after surgery and one with a gradual withdrawal of remifentanil after surgery. The primary outcome was the initial post-operative demand of analgesic medication. RESULTS: Gradual withdrawal of remifentanil was associated with a delayed initial post-operative demand of analgesic medication (P = 0.006). The first morphine bolus was given after 76.3 +/- 89.0 min in the group with a gradual withdrawal of remifentanil versus after 9.0 +/- 13.5 min in the group with an abrupt discontinuation of remifentanil. However, overall morphine consumption, numeric rating scale scores, Ramsay Sedation Scale scores, and quality of recovery scores (QoR-40) were similar in both groups (P > 0.05). CONCLUSION: Though overall morphine consumption, numeric rating scale scores, Ramsay Sedation Scale scores, and quality of recovery scores (QoR-40) are not altered, a gradual withdrawal of remifentanil after thyroid surgery is safe and associated with a delayed initial post-operative demand of analgesic drugs. The withdrawal process does, however, require vigilance and training. TRIAL REGISTRATION: Clinicaltrials.gov NCT03110653 (PI: Luc Barvais; date of registration: 03/31/2017).

Comparison of the ability of esCCO and Volume View to measure trends in cardiac output in patients undergoing cardiac surgery.

BACKGROUND: Cardiac output (CO) is a physiological variable that should be monitored during cardiac surgery. The purpose of this study was to assess the trending ability of two CO monitors, esCCO (Nihon Kohden™, Tokyo, Japan) and Volume View (VV) (Edwards Lifesciences, Irvine, USA). METHODS: A total of 19 patients were included in the study. Before cardiopulmonary bypass (CPB), CO was measured simultaneously using both esCCO and VV devices before and after three CO-modifying manoeuvres (passive leg raise [PLR], the end expiratory occlusion test [EEOT] and positive end expiratory pressure [PEEP] at 10 cm H2O). Five CO values for esCCO and three for VV were averaged and compared during a one-minute period of time before and after each manoeuvre. RESULTS: A total of 114 paired readings were collected. Median CO values were 4.3 L min⁻¹ (IQR: 3.8; 5.2) and 3.8 L min⁻¹ (IQR: 3.5; 4.5) for esCCO and VV, respectively. The precision error was 1.4% (95% CI:1.0-1.7) for esCCO and 2.2% (95% CI: 1.8-2.7) for VV. The bias between esCCO and VV values was normally distributed (P = 0.0596). Between esCCO and VV, the mean bias was +0.6 L min⁻¹ with a Limit of Agreement (LOA) of -1.8 L min⁻¹ and +3.0 L min⁻¹. The concordance rate was 43% (95% CI: 29-58) between esCCO and VV. CONCLUSION: Both single and trended measurements of CO using esCCO and VV were not in agreement. This large discrepancy leads one to the conclusion that any outcome study conducted with one of these devices cannot be applied to the other.

Different anesthetic techniques associated with different incidences of chronic post-thoracotomy pain: low-dose remifentanil plus presurgical epidural analgesia is preferable to high-dose remifentanil with postsurgical epidural analgesia.

OBJECTIVE: To investigate the relationships between 2 anesthetic techniques, or the extent of allodynia around the surgical wound, and the occurrence of chronic post-thoracotomy pain. DESIGN: Prospective, randomized study. SETTING: A single-institution, university hospital. PARTICIPANTS: Thirty-eight patients who underwent elective thoracotomy under general anesthesia. INTERVENTIONS: High-dose remifentanil (average effect-site concentration 5.61 +/- 0.84 ng/mL) with epidural analgesia started and at the end of surgery or low-dose remifentanil (average effect site concentration 1.99 +/- 0.02 ng/mL) with epidural analgesia with 0.5% ropivacaine started at the beginning of anesthesia. MEASUREMENTS AND MAIN RESULTS: Pain intensity and the extent of allodynia around the wound were measured during the hospital stay. The presence and intensity of residual pain were assessed 1, 3, and 6 months after surgery and at the end of the study (6-13 months, average 9 months). A DN4 neuropathic pain diagnostic questionnaire was conducted at the same times. In the high-dose group, the area with allodynia was three times larger than the area in the low-dose group. The increased allodynia was associated with a higher incidence of chronic pain (RR: 2.7-4.2) 3 and 6 months after surgery and at the end of the study (median follow-up: 9.5 months). CONCLUSIONS: High-dose remifentanil (0.14-0.26 microg/kg/min) without epidural analgesia during surgery is associated with a large area of allodynia around the wound. These patients develop a much higher incidence of chronic pain than those receiving low-dose remifentanil with epidural analgesia during surgery.

Assessment of thoracic epidural analgesia during general anesthesia using pupillary reflex dilation: a preliminary study.

OBJECTIVE: Pupillary reflex dilation (PRD) secondary to noxious stimulation accurately predicts sensory block during combined lumbar epidural/general anesthesia. Therefore, the adequacy of PRD-guided thoracic epidural infusion during general anesthesia for thoracotomy was studied. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Thirteen patients undergoing thoracotomy. INTERVENTIONS: An epidural catheter was placed at the T3-T4 level with initial infusion rate of 5 mL/h of ropivacaine 0.5%. Propofol/remifentanil target-controlled infusion was used for induction and maintenance of general anesthesia. Remifentanil effect site concentration was maintained constant at 0.5 ng/mL during surgery. By using a portable pupillometer, PRD secondary to tetanic stimulation of the C8, T2, and T4 segments were evaluated. Ropivacaine flow rate was adapted half hourly, according to PRD testing and a predefined algorithm. At the end of surgery, PRD was tested in the 3 investigated segments, and general anesthesia was stopped. After emergence, these zones were tested for their sensitivity to cold. Pain was evaluated by using the visual analog scale. RESULTS: Pain scores were <3 of 10 in 84.6% of the patients. Mean PRD was 0.9 +/- 0.6 mm in unblocked levels versus 0.2 +/- 0.5 mm in blocked segments (p = 0.02). PRD >or= 0.5 mm was predictive of incomplete block (sensitivity 76%, specificity 79%, and positive predictive value 86%). PRD >or= 1 mm was highly predictive of inadequate block (sensitivity 73%, specificity 91%, and positive predictive value 94%). CONCLUSION: PRD-guided continuous thoracic epidural analgesia under low-dose remifentanil/propofol anesthesia is feasible and ensures good postoperative analgesia.

The influence of a muscle relaxant bolus on bispectral and datex-ohmeda entropy values during propofol-remifentanil induced loss of consciousness.

Studies investigating the influence of muscle relaxants on the bispectral index have yielded contradictory results. In our prospective, randomized, double-blind experiments, patients received a fixed target concentration of remifentanil along with a target-controlled infusion of propofol, titrated until loss of consciousness. Two minutes after loss of consciousness, the study group received a bolus injection of atracurium, whereas the control group received a placebo. The following variables were recorded: bispectral index, spectral edge frequency, electromyographic activity, state entropy, and response entropy provided by the Datex-Ohmeda Entropy monitor. Similar values were obtained in both groups at loss of consciousness. Placebo administration induced a decrease in bispectral index (P < 0.002), spectral edge frequency (P < 0.05), electromyographic activity (P < 0.02), state entropy (P < 0.05), and response entropy (P < 0.01) compared with the values measured at loss of consciousness. Atracurium administration induced a decrease in bispectral index (P < 0.0001), spectral edge frequency (P < 0.01), electromyographic activity (P < 0.0001), state entropy (P < 0.0001), and response entropy (P < 0.0001) values. Decreases in bispectral index (P < 0.05), electromyographic activity (P < 0.0001), and response entropy (P < 0.01) were larger after atracurium than placebo injection. In lightly anesthetized patients, myorelaxant administration decreases bispectral index and response entropy, but not state entropy values.

The anterior combined approach via a single skin injection site allows lower limb anesthesia in supine patients.

PURPOSE: Lower limb anesthesia (LLA) requires the combination of, at least, three-in-one and sciatic nerve (SCN) blocks. Anterior approaches are easier to perform with minimal discomfort in supine patients, specially for traumatology. Feasibility of a single needle entry combined approach is reported. CLINICAL FEATURES: The combined landmark was applied in 119 ASA I and II patients (32-68 yr) scheduled for surgery below the knee. Needle (nerve stimulation applied through a single 150-mm long b-bevelled insulated needle) was inserted at the midpoint between the two classical approaches. Thirty and 15 mL of 0.5% ropivacaine were injected close to the femoral and the SCN, respectively. During the following 45 min, the extent of sensory block and knee and ankle motor block were assessed. Landmarks were determined within 1.7 min (0.7-2.2 min). The entire procedure was performed within 4.2 min (2.9-7.1 min) from the determination of the landmark to the SCN infiltration. The three-in-one technique was successful in 89.9% while SCN was successful in 94.9%. Femoral and tibial nerves were always blocked. Blockade of the posterior cutaneous femoral nerve was observed in 78% of patients. The extent and the quality of the sensory block always allowed surgery. Additional iv sedation was needed in 32.6% of patients. Motor block (adapted Bromage's scale > 2) was observed in the femoral (98.3%), the obturator (84.8%), the tibial (97.4%) and the common peroneal (85.7%) nerve distributions. No important adverse effects were recorded. CONCLUSION: The anterior combined approach via a single needle entry represents a technically easy and reliable technique to perform LLA in the supine patient.