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.

Microcirculatory alterations in cardiac surgery: effects of cardiopulmonary bypass and anesthesia.

BACKGROUND: Heterogeneity in microvascular perfusion is associated with impaired tissue oxygenation. We hypothesized that cardiac surgery with or without cardiopulmonary bypass (CPB) could induce microvascular alterations. METHODS: We used an orthogonal polarization spectral imaging technique to evaluate the sublingual microcirculation in patients undergoing cardiac surgery with (n = 9) or without (n = 6) CPB. We also included, as a control group, 7 patients undergoing thyroidectomy with the same anesthetic procedure. Hemodynamic and microcirculatory variables were obtained the day before surgery, after induction of anesthesia, during CPB, on admission to the intensive care unit or the recovery room, and 6 and 24 hours after the end of the surgical procedure. Data are presented as median (25th to 75th percentile). RESULTS: No differences in hemodynamic variables were observed between the two cardiac surgery groups. The proportion of perfused vessels was similar in all three groups at baseline (89% [87% to 90%]), and decreased similarly after induction of anesthesia to 71% (69% to 74%). It decreased further during CPB to 53% (50% to 56%). On admission to the intensive care unit or recovery room, alterations were more severe in CPB than in off-pump patients (60% [59% to 62%] versus 64% [61% to 65%]; p = 0.03), whereas they had already normalized in thyroidectomy patients (89% [86% to 90%]; p = 0.0005 versus cardiac surgery). In both cardiac surgery groups these microcirculatory alterations decreased with time, but persisted at 24 hours. The severity of microvascular alterations correlated with peak lactate levels after cardiac surgery (y = 11.5 - 0.15x; r(2) = 0.65; p < 0.05). CONCLUSIONS: Microcirculatory alterations are observed in cardiac surgery patients whether or not CPB is used. Anesthesia contributes to these alterations, but its effects are transient.

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 effects of acute isovolemic hemodilution on oxygenation during one-lung ventilation.

Data on the effects of isovolemic hemodilution (IH) on oxygenation during one-lung ventilation (OLV) are lacking. We studied 47 patients with hemoglobin >14 g/dL who were scheduled for lung surgery (17 with normal lung function [group NL], 17 with chronic obstructive pulmonary disease [COPD] [group COPD], and 13 with COPD as control for time/anesthesia effects [group CTRL]). Anesthesia was standardized. The tracheas were intubated with a double-lumen tube. Ventilatory settings and fraction of inspired oxygen remained constant. The study was performed with patients in the supine position before surgery. OLV was initiated for 15 min. Two-lung ventilation was reinstituted, and IH was performed (500 mL); an identical volume of hydroxyethyl starch was administered. Subsequently, OLV was again performed for 15 min. In group CTRL, the same sequences of OLV were performed without IH. At the end of each period of OLV, pulmonary mechanics and blood gases were recorded. Data were analyzed by analysis of variance (mean +/- sd). In group NL and group CTRL, the arterial oxygen partial pressure remained constant, whereas it decreased in group COPD from 119 +/- 21 mm Hg before IH to 86 +/- 16 mm Hg after IH (P <0.01). Mild IH impairs gas exchange during OLV in COPD patients, but not in patients with normal lung function.

Pulmonary vein isolation by robotic-enhanced thoracoscopy for symptomatic paroxysmal atrial fibrillation.

BACKGROUND: Pulmonary vein isolation (PVI) has been shown to be effective treatment of patients with symptomatic paroxysmal atrial fibrillation (PAF). The percutaneous approach is currently the technique of choice. Unfortunately, this procedure has limitations and complications that lead to fluctuating success rates. We explored an alternative technique of robotic-enhanced, closed-chest PVI with an endoscopic microwave-based catheter. METHODS: Seven symptomatic PAF patients were included in the study. The pulmonary veins were isolated through right (only) robotic-enhanced thoracoscopy on the beating heart. RESULTS: Six patients underwent successful endoscopic PVI. In 1 patient the operation was converted into small right thoracotomy. Operative assessment of the ablation line showed a successful electric block in every patient. Three months after the procedure, the first 5 patients were in permanent sinus rhythm. The 2 other patients had AF but had less frequent and less symptomatic episodes compared with the preoperative situation. CONCLUSIONS: On the basis of this preliminary experience, we believe that in the near future endoscopic right-chest robotic-enhanced PVI on the beating heart may become a valid option in the treatment of symptomatic PAF patients. This procedure allows for more-reproducible ablation lines and may avoid many of the pitfalls and drawbacks of the percutaneous approach. Therefore this technique deserves larger prospective evaluation in the treatment of AF.