Eric S. Schwenk

Clinical consequences of inadequate pain relief: barriers to optimal pain management.

Summary: Uncontrolled postoperative pain may result in significant clinical, psychological, and socioeconomic consequences. Not only does inadequate pain management following surgery result in increased morbidity and mortality but it also may delay recovery, result in unanticipated readmissions, decrease patient satisfaction, and lead to chronic persistent postsurgical pain. Pain is multifactorial in nature, and understanding both the complexity of pain and its side effects is imperative to achieving a successful surgical outcome. In this section, we review the consequences of pain as they pertain to plastic surgery with a focus on the impact of pain on the surgical stress response and risk of wound infections and the effect of improved pain control on flap surgery. Uncontrolled acute postoperative pain may lead to chronic persistent postsurgical pain, which has a high incidence in patients undergoing breast cancer surgery. To achieve optimal postoperative analgesia, one must recognize the barriers to effective pain management, including both physician/nursing-related barriers and patient-related barriers, as well as the increasingly common appearance of opioid-tolerant patients.

Managing Opioid-Tolerant Patients in the Perioperative Surgical Home

Management of acute postoperative pain is important to decrease perioperative morbidity and improve patient satisfaction. Opioids are associated with potential adverse events that may lead to significant risk. Uncontrolled pain is a risk factor in the transformation of acute pain to chronic pain. Balancing these issues can be especially challenging in opioid-tolerant patients undergoing surgery, for whom rapidly escalating opioid doses in an effort to control pain can be associated with increased complications. In the perioperative surgical home model, anesthesiologists are positioned to coordinate a comprehensive perioperative analgesic plan that begins with the preoperative assessment and continues through discharge.

Quantifying Cardiovascular Risks in Patients With Metabolic Syndrome Undergoing Total Joint Arthroplasty

The coexistence of diabetes, hypertension, obesity, and dyslipidemia is defined as metabolic syndrome. Studies show substantial cardiovascular risks among these patients. The risk of patients with metabolic syndrome undergoing total joint arthroplasty (TJA) is unknown. Patients with and without metabolic syndrome undergoing TJA during a 3-year period were analyzed for postoperative complications. Metabolic syndrome was defined by having 3 of the following 4 criteria: obesity (body mass index ≥30 kg/m(2)), dyslipidemia, hypertension, and diabetes. Patients with metabolic syndrome had a significantly higher risk of cardiovascular complications compared with controls (P = .017). The risk of an adverse event increased by 29% and 32%, respectively, when there were 3 or 4 syndrome components. Patients with metabolic syndrome undergoing TJA have increased risk for cardiovascular complications. Our results show that metabolic syndrome may have a clustering effect and pose increased risk when individual risks factors are combined.

Intraoperative Accuracy of a Point-of-Care Glucose Meter Compared with Simultaneous Central Laboratory Measurements

Background: Concerns have been raised about the use of point-of-care (POC) glucose meters in the hospital setting. Accuracy has been questioned especially in critically ill patients. Although commonly used in intensive care units and operating rooms, POC meters were not approved by the Food and Drug Administration for such use. Data on POC glucose meter performance during anesthesia are lacking. We evaluated accuracy of a POC meter in the intraoperative setting. Methods: We retrospectively reviewed 4,333 intraoperative records in which at least one intraoperative glucose was measured using electronic medical records at a large academic hospital. We evaluated the accuracy of a POC glucose meter (ACCU-CHEK® Inform, Roche Pharmaceuticals) based on the 176 simultaneous central laboratory (CL) blood glucose (BG) measurements that were found (i.e., documented collection times within 5 minutes). Point-of-care and central lab BG differences were analyzed by Bland-Altman and revised error grid analysis (rEGA). Results: Mean POC BG was 163.4 ± 64.7 mg/dl [minimum (min) 48 mg/dl, maximum (max) 537 mg/dl] and mean CL BG was 162.6 ± 65.1 mg/dl (min 44 mg/dl, max 502 mg/dl). Mean absolute difference between POC and CL BG was 24.3 mg/dl. Mean absolute relative difference was 16.5% with standard deviation 26.4%. Point-of-care measurements showed a bias of 0.8 relative to the corresponding CL value, with a precision of 39.0 mg/dl. Forty (23%) POC BG values fell outside the Clinical and Laboratory Standards Institute guideline and 3.4% POC measurements fell in zones C and D of the rEGA plot. Conclusions: The tested POC glucose meter performed poorly compared to a CL analyzer intraoperatively. Perioperative clinicians should be aware of limitations of specific POC glucose meters, and routine use of POC glucose meters as sole measurement devices in the intraoperative period should be carefully considered.

Ultrasound-Guided Out-of-Plane vs. In-Plane Interscalene Catheters: A Randomized, Prospective Study.

Background: Continuous interscalene blocks provide excellent analgesia after shoulder surgery. Although the safety of the ultrasound-guided in-plane approach has been touted, technical and patient factors can limit this approach. We developed a caudad-to-cephalad out-of-plane approach and hypothesized that it would decrease pain ratings due to better catheter alignment with the brachial plexus compared to the in-plane technique in a randomized, controlled study. Objectives: To compare an out-of-plane interscalene catheter technique to the in-plane technique in a randomized clinical trial. Patients and Methods: Eighty-four patients undergoing open shoulder surgery were randomized to either the in-plane or out-of-plane ultrasound-guided continuous interscalene technique. The primary outcome was VAS pain rating at 24 hours. Secondary outcomes included pain ratings in the recovery room and at 48 hours, morphine consumption, the incidence of catheter dislodgments, procedure time, and block difficulty. Procedural data and all pain ratings were collected by blinded observers. Results: There were no differences in the primary outcome of median VAS pain rating at 24 hours between the out-of-plane and in-plane groups (1.50; IQR, [0 - 4.38] vs. 1.25; IQR, [0 - 3.75]; P = 0.57). There were also no differences, respectively, between out-of-plane and in-plane median PACU pain ratings (1.0; IQR, [0 - 3.5] vs. 0.25; IQR, [0 - 2.5]; P = 0.08) and median 48-hour pain ratings (1.25; IQR, [1.25 - 2.63] vs. 0.50; IQR, [0 - 1.88]; P = 0.30). There were no differences in any other secondary endpoint. Conclusions: Our out-of-plane technique did not provide superior analgesia to the in-plane technique. It did not increase the number of complications. Our technique is an acceptable alternative in situations where the in-plane technique is difficult to perform.

Upgrading a Social Media Strategy to Increase Twitter Engagement During the Spring Annual Meeting of the American Society of Regional Anesthesia and Pain Medicine

Abstract Microblogs known as “tweets” are a rapid, effective method of information dissemination in health care. Although several medical specialties have described their Twitter conference experiences, Twitter-related data in the fields of anesthesiology and pain medicine are sparse. We therefore analyzed the Twitter content of 2 consecutive spring meetings of the American Society of Regional Anesthesia and Pain Medicine using publicly available online transcripts. We also examined the potential contribution of a targeted social media campaign on Twitter engagement during the conferences. The original Twitter meeting content was largely scientific in nature and created by meeting attendees, the majority of whom were nontrainee physicians. Physician trainees, however, represent an important and increasing minority of Twitter contributors. Physicians not in attendance predominantly contributed via retweeting original content, particularly picture-containing tweets, and thus increased reach to nonattendees. A social media campaign prior to meetings may help increase the reach of conference-related Twitter discussion.

Root causes of intraoperative hypoglycemia: a case series

STUDY OBJECTIVE To describe the root causes of intraoperative hypoglycemic events. DESIGN Retrospective analysis. SETTING Large academic teaching hospital. MEASUREMENTS Data from 80,379 ASA physical status 1, 2, 3, 4, and 5 surgical patients were reviewed. Blood glucose values, insulin, oral hypoglycemic medication doses, and doses of glucose or other medications for hypoglycemia treatment were recorded. MAIN RESULTS Hypoglycemia in many patients had multiple etiologies, with many cases (8 of 17) involving preventable errors. The most common root causes of hypoglycemia were ineffective communication, circulatory shock, failure to monitor, and excessive insulin administration. CONCLUSION Intraoperative hypoglycemia was rare, but often preventable. Better communication among providers and between providers and patients may reduce the number of intraoperative hypoglycemic events. Many transient episodes of hypoglycemia did not result in any apparent complications, rendering their clinical importance uncertain. Critically ill patients in circulatory shock represent a group that may require close glucose monitoring.

The Efficacy of Peripheral Opioid Antagonists in Opioid-Induced Constipation and Postoperative Ileus: A Systematic Review of the Literature.

Abstract Opioid-induced constipation has a negative impact on quality of life for patients with chronic pain and can affect more than a third of patients. A related but separate entity is postoperative ileus, which is an abnormal pattern of gastrointestinal motility after surgery. Nonselective &mgr;-opioid receptor antagonists reverse constipation and opioid-induced ileus but cross the blood-brain barrier and may reverse analgesia. Peripherally acting &mgr;-opioid receptor antagonists target the &mgr;-opioid receptor without reversing analgesia. Three such agents are US Food and Drug Administration approved. We reviewed the literature for randomized controlled trials that studied the efficacy of alvimopan, methylnaltrexone, and naloxegol in treating either opioid-induced constipation or postoperative ileus. Peripherally acting &mgr;-opioid receptor antagonists may be effective in treating both opioid-induced bowel dysfunction and postoperative ileus, but definitive conclusions are not possible because of study inconsistency and the relatively low quality of evidence. Comparisons of agents are difficult because of heterogeneous end points and no head-to-head studies.

Perioperative Management of Interscalene Block in Patients with Lung Disease

Interscalene nerve block impairs ipsilateral lung function and is relatively contraindicated for patients with lung impairment. We present a case of an 89-year-old female smoker with prior left lung lower lobectomy and mild to moderate lung disease who presented for right shoulder arthroplasty and insisted on regional anesthesia. The patient received a multimodal perioperative regimen that consisted of a continuous interscalene block, acetaminophen, ketorolac, and opioids. Surgery proceeded uneventfully and postoperative analgesia was excellent. Pulmonary physiology and management of these patients will be discussed. A risk/benefit discussion should occur with patients having impaired lung function before performance of interscalene blocks. In this particular patient with mild to moderate disease, analgesia was well managed through a multimodal approach including a continuous interscalene block, and close monitoring of respiratory status took place throughout the perioperative period, leading to a successful outcome.

Prevalence of discordant elevations of state entropy and bispectral index in patients at amnestic sevoflurane concentrations: a historical cohort study

BackgroundProcessed electroencephalogram (EEG) monitors help assess the hypnotic state during general anesthesia or sedation. Maintaining the bispectral index (BIS) or state entropy (SE) between 40 and 60 has been recommended to mitigate anesthesia awareness. Nonetheless, SEs > 70 were frequently observed at end-tidal sevoflurane concentrations unlikely to allow awareness. We sought to determine the prevalence of elevated discordant measurements during BIS and SE monitoring.MethodsElectronic data collected over 11 months at two academic hospitals were retrospectively reviewed. At the hospital using SE, all cases were included with patients ≥ 18 yr and sevoflurane administered for at least 30 min during surgery. A cohort of cases propensity matched by age and American Society of Anesthesiologist Physical Status were selected from the hospital using BIS. Elevated discordant EEG indices were defined as values > 70 occurring during stable end-tidal sevoflurane concentrations > 1.5%. The odds ratio (OR) based on the probability of a case having at least one elevated discordant SE or BIS lasting ≥ two minutes (primary endpoint) was calculated.ResultsAt each hospital, 3,690 cases were studied. The mean (95% confidence interval [CI]) incidence of cases with at least one interval of an elevated discordant EEG index lasting at least two minutes was 3.6% (2.8% to 4.4%) for SE compared with 0.24% (0.17% to 0.27%) for BIS (pooled OR, 17.0; 95% CI, 8.3 to 34.7; P < 0.001).ConclusionsThe prevalence of an elevated discordant EEG index is much greater with SE than with BIS. Elevated index values occurring at anesthetic concentrations well above the awareness threshold need to be assessed to determine if they indicate an inadequate depth of anesthesia requiring treatment or if they simply reflect the underlying monitoring algorithm.RésuméContexteLes moniteurs d’électroencéphalographie (EEG) dont les données ont été analysées contribuent à évaluer l’état hypnotique pendant l’anesthésie générale ou la sédation. Le maintien de l’index bispectral (BIS) ou de l’entropie basale (SE, pour state entropy) entre 40 et 60 a été recommandé pour réduire l’incidence de l’éveil peropératoire. Toutefois, des entropies basales > 70 ont fréquemment été observées à des concentrations télé-expiratoires de sévoflurane peu susceptibles de permettre un éveil. Nous avons tenté de déterminer la prévalence de mesures discordantes élevées pendant le monitorage du BIS et de l’entropie basale.MéthodeLes données électroniques colligées sur une période de 11 mois dans deux hôpitaux universitaires ont été rétrospectivement passées en revue. Dans l’hôpital utilisant l’entropie basale comme mesure, tous les cas de patients ≥ 18 ans et auxquels on avait administré du sévoflurane pour un minimum de 30 min pendant la chirurgie ont été inclus. Une cohorte de propension de cas appariés selon l’âge et le système de classification du statut physique de l’American Society of Anesthesiologists (ASA) a été sélectionnée parmi les données colligées dans un autre hôpital utilisant le BIS. On a défini les indices d’EEG discordants élevés tels que des valeurs > 70 survenant durant des concentrations télé-expiratoires stables de sévoflurane > 1,5 %. Le rapport de cotes (RC) fondé sur la probabilité d’un cas ayant au moins une valeur d’entropie basale ou de BIS discordante élevée ≥ deux minutes (critère d’évaluation principal) a été calculé.RésultatsAu total, 3690 cas ont été étudiés dans chaque hôpital. L’incidence de cas dans l’intervalle de confiance (IC) à 95 % moyen présentant au moins un intervalle d’un indice d’EEG discordant élevé durant au moins deux minutes était de 3,6 % (2,8 % à 4,4 %) lorsque l’entropie basale a été utilisée comme mesure, par rapport à 0,24 % (0,17 % à 0,27 %) lorsqu’on a utilisé le BIS (RC groupé, 17,0; IC à 95 %, 8,3 à 34,7; P < 0,001).ConclusionLa prévalence d’un indice d’EEG discordant élevé est bien plus importante avec l’entropie basale qu’avec le BIS. Des valeurs d’indice élevées survenant avec des concentrations anesthésiques bien au dessus du seuil d’éveil doivent être évaluées afin de déterminer si elles indiquent une profondeur d’anesthésie inadaptée qui nécessite un traitement ou si elles reflètent simplement l’algorithme de monitorage sous-jacent.