Observations on significant hemodynamic changes caused by a high concentration of epidurally administered ropivacaine: correlation and prediction study of stroke volume variation and central venous pressure in thoracic epidural anesthesia.

BACKGROUND: Thoracic epidural anesthesia (TEA) exacerbates hypotension due to peripheral vasodilator effects following the use of general anesthetics. This study aimed to compare the hemodynamic changes caused by three different concentrations of epidural ropivacaine and to evaluate the performance of the stroke-volume variation (SVV) and central venous pressure (CVP) during TEA with general anesthesia. METHODS: A total of 120 patients were administered 8 mL of ropivacaine solution via epidural injection, following randomization into one of three groups based on the concentration of ropivacaine in the study solution: 0.75%, 0.375%, or 0.2%. Hemodynamics were monitored for 30 min after loading. We analyzed the hemodynamic changes in the subgroups according to an age cutoff of 60 years. Receiver operating characteristic (ROC) analysis was performed to characterize the relationship of the SVV, CVP, and a 20% decrease in the mean arterial pressure (MAP) following TEA. RESULTS: Data from 109 patients were analyzed. MAP and systemic vascular resistance index were significantly decreased, and SVV was significantly increased after epidural loading only in the 0.75% ropivacaine group. There was a significant difference in hemodynamics between young and elderly subgroups in the 0.75% ropivacaine group. SVV showed a negative correlation with MAP, whereas CVP showed no correlation. The ROC analysis of SVV demonstrated a weak predictive ability of a 20% decrease in MAP at 10 min after the loading dose, with an area-under-the-curve of 0.687 and a 9.5% optimal cutoff value (sensitivity, 60.6%; specificity, 68.9%). CONCLUSIONS: A high concentration of ropivacaine through TEA caused a significant decrease in the systemic vascular resistance and blood pressure. More significant decreases were shown in the elderly patients. Though the change of SVV showed a negative correlation with hypotension and indicated functional hypovolemia after TEA, the predictability was limited. CLINICAL TRIALS REGISTRATION: Number: NCT01559285 , date: January 24, 2013.

Epidural Dexamethasone Influences Postoperative Analgesia after Major Abdominal Surgery.

BACKGROUND: Epidurally administered dexamethasone might reduce postoperative pain. However, the effect of epidural administration of dexamethasone on postoperative epidural analgesia in major abdominal surgery has been doubtful. OBJECTIVES: To investigate the effects and optimal dose of epidural dexamethasone on pain after major abdominal surgery. STUDY DESIGN: A prospective randomized, double-blind study. SETTING: University hospital. METHODS: One hundred twenty ASA physical status I and II men, scheduled for gastrectomy, were enrolled. Patients were randomly assigned to receive one of 3 treatment regimens (n = 40 in each group): dexamethasone 5 mg (1 mL) with normal saline (1 mL) (group D) or dexamethasone 10 mg (2 mL) (group E) or 2 mL of normal saline (group C) mixed with 8 mL of 0.375% ropivacaine as a loading dose. After the surgery, 0.2% ropivacaine - fentanyl 4 ?g/mL was epidurally administered for analgesia. The infusion was set to deliver 4 mL/hr of the PCEA solution, with a bolus of 2 mL per demand and 15 minutes lockout time. The infused volume of PCEA, intensity of postoperative pain using visual analogue scale (VAS) during rest and coughing, incidence of postoperative nausea and vomiting (PONV), usage of rescue analgesia and rescue antiemetic, and side effects such as respiratory depression, urinary retention, and pruritus were recorded at 2, 6, 12, 24, and 48 hours after the end of surgery. RESULTS: The resting and effort VAS was significantly lower in group E compared to group C at every time point through the study period. On the contrary, only the resting VAS in group D was lower at 2 hours and 6 hours after surgery. Total fentanyl consumption of group E was significantly lower compared to other groups. There was no difference in adverse effect such as hypotension, bradycardia, PONV, pruritis, and urinary retention among groups. LIMITATIONS: Use of epidural PCA with basal rate might interrupt an accurate comparison of dexamethasone effect. Hyperglycemia and adrenal suppression were not evaluated. CONCLUSIONS: Epidural dexamethasone was effective for reducing postoperative pain. Especially, an epidural dexamethasone dose of 10 mg was more effective than a lower dose in patients undergoing gastrectomy which was associated with moderate to severe postoperative pain.

The effect of tulobuterol patches on the respiratory system after endotracheal intubation.

BACKGROUND: Endotracheal intubation during anesthesia induction may increase airway resistance (Raw) and decrease dynamic lung compliance (Cdyn). We hypothesized that prophylactic treatment with a transdermal ß2-agonist tulobuterol patch (TP) would help to reduce the risk of bronchospasm after placement of the endotracheal tube. METHODS: Eighty-two American Society of Anesthesiologists (ASA) category I or II adult patients showing obstructive patterns were divided randomly into a control and a TP group (n = 41 each). The night before surgery, a 2-mg TP was applied to patients in the TP group. Standard monitors were recorded, and target controlled infusion (TCI) with propofol and remifentanil was used for anesthesia induction and maintenance. Simultaneously, end-tidal carbon dioxide, Raw, and Cdyn were determined at 5, 10, and 15 min intervals after endotracheal intubation. RESULTS: There was no significant difference in demographic data between the two groups. The TP group was associated with a lower Raw and a higher Cdyn, as compared to the control group. Raw was significantly lower at 10 min (P < 0.05) and 15 min (P < 0.01), and Cdyn was significantly higher at 5 min (P < 0.05) and 15 min (P < 0.01) in the TP group. A trend towards a lower Raw was observed showing a statistically significant difference 5 min after endotracheal intubation (P < 0.01) in each group. CONCLUSIONS: Prophylactic treatment with TP showed a bronchodilatory effect through suppressing an increase in Raw and a decrease in Cdyn after anesthesia induction without severe adverse effects.

The EC(50) of remifentanil to minimize the cardiovascular changes during head holder pinning in neurosurgery.

BACKGROUND: During neuroanesthesia, head holder pinning commonly results in sympathetic stimulation manifested by hemodynamic changes, such as increased heart rate and arterial blood pressure. Remifentanil has been used successfully to control acute autonomic responses during neurosurgical procedures. The objective of this study was to determine effect-site concentration of remifentanil for suppressing the hemodynamic response to head holder pinning with the probability of 50% (EC(50)). METHODS: Forty-one ASA physical status I or II patients, between the ages of 20-70, who were scheduled for neurosurgery were recruited into this study. After arrival in the operating room, standard monitoring was applied throughout the study, which included a bispectral index monitor. Both propofol and remifentanil were administered by Target-control infusion device. The Dixon "up-and-down" sequential allocation method was used to determine the EC(50) of remifentanil. RESULTS: The EC(50) of remifentanil was 2.19 ± 0.76 ng/ml by the turning point estimate (TPE). In probit analysis, EC(50) was 2.42 ng/ml (95% CI : -0.62-4.66) and EC(95) was 5.70 ng/ml (95% CI : 4.02-67.53). The EC(50) estimator comes from isotonic regression is 2.90 ng/ml (95% CI : 1.78-3.65). The EC(95) estimator comes from isotonic regression is 4.28 ng/ml (95% CI : 3.85-4.41). CONCLUSIONS: This study showed that EC(50) of remifentanil was 2.19 ± 0.76 ng/ml by TPE. EC(50) was 2.42 ng/ml (95% CI -0.62-4.66) in probit analysis, as back up analysis. The EC(50) estimator comes from isotonic regression is 2.90 ng/ml (95% CI : 1.78-3.65).