Lidocaine 5% Patch for Treatment of Acute Pain After Robotic Cardiac Surgery and Prevention of Persistent Incisional Pain: A Randomized, Placebo-Controlled, Double-Blind Trial.

OBJECTIVES: To test the hypotheses that lidocaine 5% patches decrease the severity of acute pain and incidence of persistent incisional pain after robotic cardiac valve surgery. DESIGN: A randomized, placebo-controlled, double-blind trial. SETTING: Tertiary care academic medical center. SUBJECTS: Patients having robotic cardiac valve surgery. METHODS: Patients having robotic cardiac valve surgery were randomly assigned to 5% lidocaine patches or identical-appearing placebo patches. Patches were applied around each incision 12 hours/day until pain resolved, or for 6 months. Supplemental opioid was provided by patient-controlled analgesia or orally. Pain was initially evaluated with a Visual Analog Scale, and subsequently by telephone with a Verbal Response Scale and the Pain Disability Index (our primary outcome) after 1 week, 1 month, 3 months, and 6 months. Global Perceived Effect, a measure of patient satisfaction, was simultaneously recorded. Repeated-measures analysis of variance and generalized estimating equations were our primary statistical tools. RESULTS: Acute pain scores and opioid use were low, as was the incidence of persistent pain. Lidocaine 5% patches did not influence any measure of acute or persistent incisional pain. Estimated difference (95% CI) in mean Pain Disability Index for Lidocaine patch minus placebo was -2.5 (95% CI -7.1, 2.1), P = 0.28. CONCLUSIONS: Lidocaine 5% patches did not reduce acute or persistent pain in patients having robotic thoracic surgery, though pain scores were low in both treatment groups. Clinicians should choose alternative analgesic approaches in these patients.

Chronic intermittent hypoxia is independently associated with reduced postoperative opioid consumption in bariatric patients suffering from sleep-disordered breathing.

BACKGROUND: Evidence suggests that recurrent nocturnal hypoxemia may affect pain response and/or the sensitivity to opioid analgesia. We tested the hypothesis that nocturnal hypoxemia, quantified by sleep time spent at an arterial saturation (SaO2) < 90% and minimum nocturnal SaO2 on polysomnography, are associated with decreased pain and reduced opioid consumption during the initial 72 postoperative hours in patients having laparoscopic bariatric surgery. METHODS: With Institutional Review Board approval, we examined the records of all patients who underwent laparoscopic bariatric surgery between 2004 and 2010 and had an available nocturnal polysomnography study. We assessed the relationships between the time-weighted average of pain score and total opioid consumption during the initial 72 postoperative hours, and: (a) the percentage of total sleep time spent at SaO2 < 90%, (b) the minimum nocturnal SaO2, and (c) the number of apnea/hypopnea episodes per hour of sleep. We used multivariable regression models to adjust for both clinical and sleep-related confounders. RESULTS: Two hundred eighteen patients were included in the analysis. Percentage of total sleep time spent at SaO2 < 90% was inversely associated with total postoperative opioid consumption; a 5-%- absolute increase in the former would relatively decrease median opioid consumption by 16% (98.75% CI: 2% to 28%, P = 0.006). However, the percentage of total sleep time spent at SaO2 < 90% was not associated with pain. The minimum nocturnal SaO2 was associated neither with total postoperative opioid consumption nor with pain. In addition, neither pain nor total opioid consumption was significantly associated with the number of apnea/hypopnea episodes per hour of sleep. CONCLUSIONS: Preoperative nocturnal intermittent hypoxia may enhance sensitivity to opioids.

Low serum vitamin D levels are not associated with increased postoperative pain and opioid requirements: a historical cohort study.

PURPOSE: Vitamin D deficiency has been associated with chronic non-specific musculoskeletal pain syndromes; however, studies are lacking with respect to its relationship with postoperative pain. We tested the hypothesis that a lower preoperative vitamin D level is associated with increased postoperative pain and/or opioid consumption in morbidly obese patients who had laparoscopic bariatric surgery. METHODS: Data from 185 patients who underwent laparoscopic bariatric surgery at the Cleveland Clinic from 2005-2009 and had a vitamin D level checked within three months of their surgery were included in the analysis. We assessed the relationship between vitamin D levels and the time-weighted average (TWA) of pain scores and total opioid consumption using multivariable regression models adjusted for potential confounders. As a secondary analysis, we compared the TWA of pain scores and opioid consumption between patients who were vitamin D deficient (≤ 20 ng·mL(-1)) and those who were not (vitamin D > 20 ng·mL(-1)). RESULTS: The mean (SD) TWA pain score was 3.8 (1.5) and the median interquartile range [IQR] total opioid consumption (morphine equivalent) was 15.6 [18.2] mg during the first 72 hr postoperatively. The median [IQR] vitamin D concentration was 21.8 [17.1] ng·mL(-1). The vitamin D level was not significantly associated with either the TWA pain score (Pearson correlation: -0.003; 97.5% confidence interval [CI]: -0.17 to 0.16) or opioid consumption (Spearman correlation: -0.13; 97.5% CI: -0.30 to 0.03). After adjusting for confounders, the estimated average change in TWA pain score was 0.01 (97.5% CI: -0.08 to 0.11) for a five-unit increase in vitamin D (P = 0.77). The estimated ratio of geometric means of total opioid consumption was 0.94 (97.5% CI: 0.86 to 1.03) for a five-unit increase in vitamin D concentration (P = 0.12). No difference was found between patients with vitamin D concentrations > 20 ng·mL(-1) and ≤ 20 ng·mL(-1) in either TWA pain score (P = 0.91) or total opioid consumption (P = 0.18). CONCLUSION: We did not find any association between preoperative vitamin D levels and postoperative pain scores/opioid consumption in morbidly obese patients undergoing bariatric surgery.

Relationship between chronic intermittent hypoxia and intraoperative mean arterial pressure in obstructive sleep apnea patients having laparoscopic bariatric surgery.

BACKGROUND: Recurrent nocturnal hypoxemia in obstructive sleep apnea enhances sympathetic function, decreases baroreceptor sensitivity, and weakens peripheral vascular responses to adrenergic signals. The authors hypothesized that the percentage of total sleep time spent at oxyhemoglobin saturation (SaO2) less than 90% and minimum nocturnal SaO2 on preoperative polysomnography are associated with decreased intraoperative mean arterial pressure. METHODS: The authors examined the records of all patients who had laparoscopic bariatric surgery at Cleveland Clinic between 2005 and 2009 and an available polysomnography study. The authors assessed the relationships between the percentage of total sleep time spent at SaO2 less than 90% and minimum nocturnal SaO2, and the time-weighted average of mean arterial pressure. The authors used multivariable regression models to adjust for prespecified clinical confounders. RESULTS: Two hundred eighty-one patients were included in the analysis. The average change in the time-weighted average of mean arterial pressure was -0.02 (97.5% CI, -0.08, 0.04) mmHg for each 1% absolute increase in the percentage of sleep time spent at SaO2 less than 90% (P = 0.50). The average change was -0.13 (97.5% CI, -0.27, 0.01) mmHg, for each 1% absolute decrease in the minimum SaO2 (P = 0.04 > significance criterion of 0.025, Bonferroni correction). An unplanned analysis estimated 1% absolute decrease in minimum SaO2 was associated with -0.22 (98.75% CI, -0.39, -0.04) mmHg, change in mean arterial pressure (P = 0.002) in the time period between endotracheal intubation and trocar insertion. CONCLUSION: Recurrent nocturnal hypoxemia in obstructive sleep apnea is not a risk marker for intraoperative hypotension.

Treatment and pathogenesis of acute hyperkalemia.

This article focuses on the pathogenesis, clinical manifestations, and various treatment modalities for acute hyperkalemia and presents a systematic approach to selecting a treatment strategy. Hyperkalemia, a life-threatening condition caused by extracellular potassium shift or decreased renal potassium excretion, usually presents with non-specific symptoms. Early recognition of moderate to severe hyperkalemia is vital in preventing fatal cardiac arrhythmias and muscle paralysis. Management of hyperkalemia includes the elimination of reversible causes (diet, medications), rapidly acting therapies that shift potassium into cells and block the cardiac membrane effects of hyperkalemia, and measures to facilitate removal of potassium from the body (saline diuresis, oral binding resins, and hemodialysis). Hyperkalemia with potassium level more than 6.5 mEq/L or EKG changes is a medical emergency and should be treated accordingly. Treatment should be started with calcium gluconate to stabilize cardiomyocyte membranes, followed by insulin injection, and b-agonists administration. Hemodialysis remains the most reliable method to remove potassium from the body and should be used in cases refractory to medical treatment. Prompt detection and proper treatment are crucial in preventing lethal outcomes.