16<\/a>], with all other intraoperative management identical to that of the L group.<\/p>\nAnesthesia protocol description<\/p>\n
Patients fasted for 8\u00a0h and abstained from drinking fluids for 2\u00a0h preoperatively. Upon admission to the operating room, a warming blanket was placed on the bed and adjusted to a temperature of 33\u00a0\u00b0C. Standard monitoring procedures were implemented, and intravenous access was established.<\/p>\n
General anesthesia was induced with sufentanil 0.3\u00a0\u00b5g\/kg, propofol 1.5\u20132\u00a0mg\/kg, and rocuronium bromide 0.6\u00a0mg\/kg. Following successful endotracheal intubation, patients were connected to a mechanical ventilator with the following settings: tidal volume 6\u20138 mL\/kg, respiratory rate 12\u201314 breaths\/min, inspiratory-to-expiratory ratio 1:2, inspired oxygen concentration 100%, and oxygen flow rate 2\u00a0L\/min. End-tidal carbon dioxide (ETCO\u2082) was maintained between 35 and 45 mmHg throughout surgery. Anesthesia maintenance included target-controlled infusion (TCI) of remifentanil at 1.0\u20133.0 ng\/mL and inhalational sevoflurane to maintain a minimum alveolar concentration (MAC) of 0.8\u20131.0. Rocuronium bromide 0.3\u00a0mg\/kg was administered intermittently as needed. Intraoperative fluid management was standardized across all patients. The total fluid volume administered was determined by integrating the following components: (1) Maintenance fluid requirements were calculated according to the Holliday-Segar formula (4 mL\/kg\/h for the first 10\u00a0kg, 2 mL\/kg\/h for the next 10\u00a0kg, and 1 mL\/kg\/h for each additional kg); (2) The preoperative fasting deficit was estimated as the maintenance rate multiplied by the hours of fasting; (3) Ongoing losses, such as blood loss and urinary output, were replaced milliliter-for-milliliter using crystalloid or colloid solutions as clinically indicated; (4) Third-space insensible losses were estimated at 4\u20136 mL\/kg\/h based on the extent of surgical trauma. The initial fluid deficit was fully replaced within the first hour of surgery. Subsequently, a continuous infusion was maintained to cover ongoing maintenance requirements, losses, and third-space sequestration. All fluid administration was guided by continuous hemodynamic monitoring, including arterial pressure and heart rate. The protocol permitted clinician-directed adjustments in response to significant hemodynamic variations.<\/p>\n
During both induction and maintenance of anesthesia, HR and mean arterial pressure (MAP) fluctuations were controlled within 20% of baseline values. If necessary, ephedrine, atropine, nicardipine, or esmolol was administered to maintain hemodynamic stability. The target-controlled infusion (TCI) of remifentanil was dynamically titrated according to the patient\u2019s hemodynamic response to surgical stimuli. The goal was to maintain HR and MAP within \u00b1\u200920% of pre-induction baseline values. The titration protocol was as follows: if HR or MAP exceeded 120% of baseline, suggesting potential insufficient analgesia or anesthetic depth, the remifentanil TCI target concentration was increased within the predefined range (1.0\u20133.0 ng\/mL). Conversely, if HR or MAP fell below 80% of baseline, indicating possible excessive depth or vasodilation, the target concentration was reduced. A stable volatile anesthetic background was maintained using sevoflurane at an end-tidal concentration of 0.8\u20131.0 MAC to ensure hypnosis and amnesia. Remifentanil adjustments were made complementarily to this baseline to specifically modulate nociceptive responses reflected in hemodynamic changes. In cases where hemodynamic parameters persistently deviated beyond the \u00b1\u200920% threshold despite optimization of remifentanil and sevoflurane, adjuvant agents were administered as needed: ephedrine for hypotension, nicardipine or esmolol for hypertension or tachycardia, and atropine for significant bradycardia.<\/p>\n
Nasopharyngeal temperature was measured, and the warming blanket was adjusted to maintain the nasopharyngeal temperature between 36 and 37\u00a0\u00b0C. Approximately 30\u00a0min before the end of surgery, additional sufentanil 10\u00a0\u00b5g and tropisetron 4\u00a0mg were administered. At the end of surgery, remifentanil infusion was discontinued, the sevoflurane MAC was reduced to 0.3, and the lidocaine infusion was stopped. Extubation was performed once the patient exhibited signs of awakening, including eye opening, clear consciousness, recovery of cough reflex, and restoration of adequate tidal volume, after which the patient was transferred to the post-anesthesia care unit (PACU) for observation.<\/p>\n
All patients received postoperative intravenous patient-controlled analgesia (PCIA). The PCIA formulation consisted of sufentanil 100\u00a0\u00b5g, nalbuphine 60\u00a0mg, tropisetron 6\u00a0mg, and dexamethasone 10\u00a0mg, diluted with normal saline to a total volume of 150 mL. The initial bolus was 3 mL, with a continuous infusion rate of 2.5 mL\/h, a patient-controlled bolus dose of 1.5 mL, and a lockout interval of 15\u00a0min. When postoperative pain scores exceeded 4 on the NRS scale, an intramuscular injection of diclofenac sodium lidocaine 2 mL was administered.<\/p>\n
Outcomes<\/p>\n
The primary outcome was the postoperative pain intensity, assessed using the NRS (NRS; 0\u2009=\u2009no pain, 1\u20133\u2009=\u2009mild, 4\u20136\u2009=\u2009moderate, 7\u201310\u2009=\u2009severe) at the following time points: upon admission to the post-anesthesia care unit (PACU), at PACU discharge, and at 12, 24, 48, and 72\u00a0h after surgery.<\/p>\n
The secondary outcomes included: (1) The number of patient-controlled analgesia (PCA) presses recorded at 12, 24, and 48\u00a0h postoperatively; (2) Total postoperative opioid consumption. (3) Requirement of intraoperative vasopressors (ephedrine dosage). (4) Modified Observer\u2019s Assessment of Alertness\/Sedation (MOAA\/S) scores upon PACU admission; (5) Incidence of postoperative adverse events including nausea, vomiting, tachycardia, hypertension, bradycardia, hypotension, and pruritus, within 48\u00a0h.<\/p>\n
Sample size calculation<\/p>\n
Preliminary experiments indicated that postoperative pain NRS scores did not follow a normal distribution; therefore, a nonparametric method was used for sample size calculation. Using PASS software with the sample size calculation module associated with the Kruskal-Wallis test, the power was set at 0.8 (Power\u2009=\u20090.8) and the significance level at \u03b1\u2009=\u20090.05. In the pilot study, 27 patients (9 per group) were enrolled. Shapiro-Wilk tests confirmed that postoperative resting NRS scores at 24\u00a0h were not normally distributed. The median (Q1, Q3) for each group were as follows: Low-dose group (L group): 4 (3, 5); Medium-dose group (M group): 3 (2, 4); High-dose group (H group): 2 (1, 3).<\/p>\n
Based on preliminary experimental data, the intergroup rank-sum differences were calculated and converted into an effect size indicator, yielding a value of 0.3. Using PASS software, and considering a potential patient dropout rate of 20%, the final calculated total sample size required for this study was 75 cases, with approximately 25 cases allocated to each group. During actual enrollment, to account for the complexity of perioperative variables and to ensure the feasibility of subgroup analyses, 38 patients were ultimately included in each group, resulting in a total sample size of 114 cases. Through strengthened follow-up management during the study period, the dropout rate was controlled to below 5%. The final number of cases completed was as follows: 38 cases in the L group, 38 cases in the M group, and 38 cases in the H group.<\/p>\n
Statistical analysis<\/p>\n
Data were analyzed using SPSS 20.0 statistical software. Compliance with normal distribution was examined using the Shapiro-Wilk Test. Categorical data are presented as frequence, and quantitative data as mean\u2009\u00b1\u2009standard deviation or median (Q1,Q3). One-way analysis of variance (ANOVA) with Bonferroni correction was used to compare normally distributed quantitative data among three groups, while the Kruskal Wallis test with Dunn\u2019s correction was used to compare the non-normally distributed data. The chi-square test was used for the comparison of categorical variables among groups. Additionally, repeated-measures ANOVA with post hoc Bonferroni test was employed to compare more than two groups, with group as the between-subject factor and time point as the within-subject factor. P\u2009<\/p>\n","protected":false},"excerpt":{"rendered":"Study population This study was approved by the Ethics Committee of the Affiliated Cancer Hospital of Guizhou Medical…\n","protected":false},"author":2,"featured_media":190915,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[78],"tags":[72535,106573,18,106575,28667,135,19,61134,1911,17,106572,106574],"class_list":{"0":"post-190914","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-health","8":"tag-anesthesiology","9":"tag-colorectal-surgery","10":"tag-eire","11":"tag-elderly-patients","12":"tag-emergency-medicine","13":"tag-health","14":"tag-ie","15":"tag-intensive-critical-care-medicine","16":"tag-internal-medicine","17":"tag-ireland","18":"tag-lidocaine","19":"tag-quadratus-lumborum-block"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/115582662318700144","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/190914","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=190914"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/190914\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/190915"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=190914"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=190914"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=190914"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}