Intravenous patient-controlled analgesia does not increase the risk of postoperative delirium compared to patient-controlled epidural analgesia: a propensity score-matched retrospective cohort study.

BACKGROUND: It is unclear whether the doses of opioids and the routes of administration used for postoperative analgesic management are associated with delirium. We aimed to compare the incidence of postoperative delirium (POD) between intravenous patient-controlled analgesia (IVPCA) and patient-controlled epidural analgesia (PCEA) in patients who underwent postoperative analgesic management using opioids. METHODS: We retrospectively investigated surgical patients (n=3,324) who received patient-controlled analgesia (PCA). Morphine was used for IVPCA, and fentanyl and ropivacaine were used for PCEA. The patients' background characteristics, perioperative management, presence of POD, and postoperative analgesia technique after IVPCA (n=1,184) or PCEA (n=2,140) were assessed. We divided the patients into IVPCA and PCEA groups and compared the incidence of POD by propensity score matching. We used the independent t-test for comparisons between the groups, and P<0.05 as considered as statistically significant. RESULTS: POD was noted in a total of 125 patients (3.8%); 55 patients (4.6%) with IVPCA and 70 patients (3.3%) with PCEA (P=0.046). There was no statistically significant difference in cumulative opioid usage up to postoperative day 2 (in mg) between patients with and without POD (POD 62.7±39.8 vs. non-POD 48.9±50.3, P=0.10). After propensity score matching, 1,156 patients with similar baseline characteristics were selected. POD was noted in 22 of 578 patients (3.8%) in the IVPCA group and 30 of 578 patients (5.2%) in the PCEA group, with no difference between the two groups (P=0.256). On the other hand, opioid usage was higher in the IVPCA group than in the PCEA group (P<0.001). CONCLUSIONS: There was no difference in the incidence of POD between morphine IVPCA and fentanyl PCEA when the patient characteristics were matched using propensity score matching. POD occurs regardless of the route and dose of opioid administration.

Relationship Between the Loaded Pressure and Flow Rate of Packed Red Blood Cells and Various Infusion Solutions in Normal Infusion Lines and Catheters.

BACKGROUND: We investigated the relationship between the loaded pressure and flow rate in various catheters and the entire infusion line including the catheters, in several infusion solutions and packed red blood cells. METHODS: We connected the infusion line and catheter to the infusion solution and used an outer pressure bag or a compressor to pressurize the infusion solution bag to a pressure within the clinical (up to 450 mm Hg) or higher range (up to 1050 mm Hg). We approximated the relationship between the loaded pressure and flow rate in the entire infusion line including the catheter, versus the catheter alone, as a power function and compared the power numbers. RESULTS: In the clinical pressure range of normal saline, the power numbers of the entire infusion line for the 24-, 22-, 20-, and 18-gauge catheters were 0.76, 0.82, 0.81, and 0.86, respectively, while those for the catheter alone were 0.67, 0.63, 0.56, and 0.44, respectively. In the higher pressure range of normal saline, the power numbers of the entire infusion line for the 24-, 22-, 20-, and 18-gauge catheters were 0.68, 0.70, 0.71, and 0.73, respectively, while those for the catheter alone were 0.62, 0.61, 0.59, and 0.58, respectively. As the power number of the entire infusion line was closer to 1.00 than the values of the catheter, the relation between the loaded pressure and the flow rate was more linear in the entire infusion line than that in the catheter. Similar results were obtained using packed red blood cells and 40% glycerin mixture in normal saline. CONCLUSIONS: Regardless of the type of infusion solution or transfusion, the pressure-flow relationship in the catheter was nonlinear and not directly proportional. However, within the clinical pressure range (up to 450 mm Hg), the relationship between the flow rate and pressure in the entire infusion line was almost linear and proportional.

Prediction of blood pressure change during surgical incision under opioid analgesia using sympathetic response evoking threshold.

Opioid inhibition of nociceptive stimuli varies in individuals and is difficult to titrate. We have reported the vascular stiffness value (K) as a standard monitor to quantify sympathetic response with high accuracy. On the contrary, among individuals, a considerable variation in the rate of change in K for constant pain has been observed. In this study, we proposed a new index, the minimum stimulus intensity value that evoked the response on K (MECK: Minimum Evoked Current of K), and evaluated its accuracy in predicting sympathetic response to nociceptive stimuli under constant opioid administration. Thirty patients undergoing open surgery under general anesthesia were included. After anesthetic induction, remifentanil was administered at a constant concentration of 2 ng/ml at the effect site followed by tetanus stimulation. MECK was defined as the minimal current needed to produce a change in K. MECK significantly (P < 0.001) correlated with the rate of change of systolic blood pressure during skin incision (ROCBP). Bland-Altman plot analysis using the predicted ROCBP calculated from MECK and the measured ROCBP showed that the prediction equation for ROCBP was highly accurate. This study showed the potential of MECK to predict blood pressure change during surgical incision under opioid analgesia.Clinical trial registration Registry: University hospital medical information network; Registration number: UMIN000041816; Principal investigator's name: Satoshi Kamiya; Date of registration: July 9th, 2019.

Impact of fentanyl on acute and chronic pain and its side effects when used with epidural analgesia after thoracic surgery in multimodal analgesia: a retrospective cohort study.

BACKGROUND: We investigated the effects adding opioids to epidural anesthesia on acute and chronic pain and its side effects in multimodal analgesia. METHODS: Retrospective cohort study. We retrospectively studied patients who received epidural anesthesia after thoracic surgery. Patients were divided into two groups: epidural anesthesia with fentanyl (group F) and without fentanyl (group N). Pain visual analog scale (VAS) scores at rest and after movement, use of non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen, side effects (nausea, vomiting, pruritus, hypotension, urinary retention), and post-thoracotomy pain syndrome (PTPS) were compared between the two groups. A Mann-Whitney U test and chi-squared test were used for statistical analysis, with significance set at P<0.05. Values were presented as median [interquartile range]. RESULTS: A total of 282 patients received epidural anesthesia, 142 in group F and 140 in group N. Resting pain and movement pain were lower in group F than those in group N {resting pain: group F 12 [0-29], group N 20.5 [7-38.5], P=0.01; movement pain, group F 43 [17-65]; group N, 51.5 [39-72]; P<0.001}. Incidence of hypotension was 9.9% in group F and 2.1% in group N (P=0.01), and that of pruritus was 41.5% in group F and 10.7% in group N (P<0.001). There is no difference in the incidence of nausea and vomiting and PTPS. CONCLUSIONS: In multimodal analgesia management after thoracic surgery, the addition of fentanyl to epidural anesthesia reduced acute pain and increased the incidence of hypotension and pruritus but did not affect that of PTPS.