Kamal Maheshwari

Relationship between Intraoperative Hypotension, Defined by Either Reduction from Baseline or Absolute Thresholds, and Acute Kidney and Myocardial Injury after Noncardiac Surgery: A Retrospective Cohort Analysis.

Background: How best to characterize intraoperative hypotension remains unclear. Thus, the authors assessed the relationship between myocardial and kidney injury and intraoperative absolute (mean arterial pressure [MAP]) and relative (reduction from preoperative pressure) MAP thresholds. Methods: The authors characterized hypotension by the lowest MAP below various absolute and relative thresholds for cumulative 1, 3, 5, or 10 min and also time-weighted average below various absolute or relative MAP thresholds. The authors modeled each relationship using logistic regression. The authors further evaluated whether the relationships between intraoperative hypotension and either myocardial or kidney injury depended on baseline MAP. Finally, the authors compared the strength of associations between absolute and relative thresholds on myocardial and kidney injury using C statistics. Results: MAP below absolute thresholds of 65 mmHg or relative thresholds of 20% were progressively related to both myocardial and kidney injury. At any given threshold, prolonged exposure was associated with increased odds. There were no clinically important interactions between preoperative blood pressures and the relationship between hypotension and myocardial or kidney injury at intraoperative mean arterial blood pressures less than 65 mmHg. Absolute and relative thresholds had comparable ability to discriminate patients with myocardial or kidney injury from those without. Conclusions: The associations based on relative thresholds were no stronger than those based on absolute thresholds. Furthermore, there was no clinically important interaction with preoperative pressure. Anesthetic management can thus be based on intraoperative pressures without regard to preoperative pressure.

Bilateral Continuous Quadratus Lumborum Block for Acute Postoperative Abdominal Pain as a Rescue After Opioid-Induced Respiratory Depression.

We present a case of acute postoperative abdominal pain after proctosigmoidectomy and colorectal anastomosis that was treated by bilateral continuous quadratus lumborum block. The block was performed in the lateral position under ultrasound guidance with a 15-mL bolus of 0.5% bupivacaine injected anterior to the quadratus lumborum muscle followed by bilateral catheter placement. Each catheter received a continuous infusion of 0.1% bupivacaine at 8 mL/h and an on-demand bolus 5 mL every 30 minutes. Sensory level was confirmed by insensitivity to cold from T7 through T12. The block was devoid of hemodynamic side effects or motor weakness. This case demonstrates that bilateral continuous quadratus lumborum catheters can provide extended postoperative pain control.

An Update of the Role of Renin Angiotensin in Cardiovascular Homeostasis

The renin angiotensin system (RAS) is thought to be the body’s main vasoconstrictor system, with physiological effects mediated via the interaction of angiotensin II with angiotensin I receptors (the “classic” RAS model). However, since the discovery of the heptapeptide angiotensin 1–7 and the development of the concept of the “alternate” RAS system, with its ability to reduce arterial blood pressure, our understanding of this physiologic system has changed dramatically. In this review, we focus on the newly discovered functions of the RAS, particularly the potential clinical significance of these developments, especially in the realm of new pharmacologic interventions for treating cardiovascular disease.

The renin angiotensin system and the brain: New developments

The traditional renin-angiotensin system (RAS) is indispensable system in adjusting sodium homeostasis, body fluid volume, and controlling arterial blood pressure. The key elements are renin splitting inactive angiotensinogen to yield angiotensin (Ang-I). Ang-1 is then changed by angiotensin-1 converting enzyme (ACE) into angiotensin II (Ang-II). Using PubMed, Google Scholar, and other means, we searched the peer-reviewed literature from 1990 to 2013 for articles on newly discovered findings related to the RAS, especially focusing on how the system influences the central nervous system (CNS). The classical RAS is now considered to be only part of the picture; the discovery of additional RAS pathways in the brain and elsewhere has yielded a vastly improved understanding of how the RAS influences the CNS. Newly discovered effects of the RAS on brain tissue include neuroprotection, cognition, and cerebral vasodilation. A number of brain biochemical pathways are influenced by the brain RAS. Within various pathways, there are potential opportunities for classical pharmacologic interventions as well as the possibility of controlling gene expression.

A temporal analysis of opioid use, patient satisfaction, and pain scores in colorectal surgery patients

BACKGROUND Recent health care policy changes promote objective measurements of patient satisfaction with care provided during hospitalization. Acute postsurgical pain is a significant medical problem and strongly impacts patient experience and patient satisfaction. Multimodal analgesic pathways are used for acute pain management, but opioid medications remain a mainstay of treatment. Opioid use is increasing in the outpatient setting, but opioid use trends in the inpatient postsurgical setting are not well known. We hypothesized that use of opioid medications has increased over time along with decrease in postoperative pain scores and increase in pain-related patient satisfaction. METHODS In this single-center study, we studied the trends and correlation in the average daily pain scores, opioid consumption, and patient satisfaction scores as measured by pain-related patient satisfaction questions in the Hospital Consumer Assessment of Healthcare Providers and System survey. Pain scores and opioid use data were obtained from electronic health records, vital signs monitoring, and medication databases. Adult patients who had nonemergent colorectal surgeries between January 2009 and December 2012 were included. RESULTS We found no significant trend in opioid use or pain-related patient satisfaction scores. There was an average annual increase of 0.3 (98.3% confidence interval, 0.2-0.4; P< .001) in average daily pain score from 2.8 ± 1.5 to 3.8 ± 1.5. The univariable associations between time-weighted pain score, average daily opioid dose, and pain-related patient satisfaction score were all highly significant. CONCLUSION In this retrospective cohort study, opioid use and pain-related patient satisfaction scores were stable over time. Pain-related patient satisfaction scores were negatively associated with both pain score and opioid dose. The associations we report should not be considered evidence of a causal relationship.

Early Surgery Confers 1-year Mortality Benefit in Hip-fracture Patients

Background: To evaluate the relationship between surgical timing and 1-year mortality in patients requiring hip fracture repair. Methods: We analyzed all 720 patients (>65 years) who had hip fracture surgery between March 2005 and February 2015, identifying patients by ICD-9 diagnosis and procedure codes using electronic data query. Mortality data were obtained from the institutional database, state and Social Security Death Indices. The relationship between surgical timing (defined as the interval from admission to the start of surgery) and 1-year mortality was assessed using a multivariable logistic regression, adjusting for baseline clinical status and surgical factors. Results: Among the 720 patients, 159 patients (22%) died within 1 year. The median time from admission to surgery was 30 hours. A linear relationship between the surgical timing and 1-year mortality was demonstrated. Delaying surgery was significantly associated with increased 1-year mortality, odds ratio 1.05 (95% CI: 1.02–1.08) per 10-hour delay (P = 0.001). Conclusions: A linear relationship was observed between surgical timing and 1-year mortality. Each 10-hour delay from admission to surgery was associated with an estimated 5% higher odds of 1-year mortality. Therefore, we suggest that hip fractures should be treated urgently similar to other time-sensitive pathology such as stroke and myocardial ischemia. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Attempted Development of a Tool to Predict Anesthesia Preparation Time From Patient-Related and Procedure-Related Characteristics

BACKGROUND: Operating room (OR) utilization generally ranges from 50% to 75%. Inefficiencies can arise from various factors, including prolonged anesthesia preparation time, defined as the period from induction of anesthesia until patients are considered ready for surgery. Our goal was to use patient-related and procedure-related factors to develop a model predicting anesthesia preparation time. METHODS: From the electronic medical records of adults who had noncardiac surgery at the Cleveland Clinic Main Campus, we developed a model that used a dozen preoperative factors to predict anesthesia preparation time. The model was based on multivariable regression with “Least Absolute Shrinkage and Selection Operator” and 10-fold cross-validation. The overall performance of the final model was measured by R2, which describes the proportion of the variance in anesthesia preparation time that is explained by the model. RESULTS: A total of 43,941 cases met inclusion and exclusion criteria. Our final model had only moderate discriminative ability. The estimated adjusted R2 for prediction model was 0.34 for the training data set and 0.27 for the testing data set. CONCLUSIONS: Using preoperative factors, we could explain only about a quarter of the variance in anesthesia preparation time—an amount that is probably of limited clinical value.

Novel needle guide reduces time to perform ultrasound-guided femoral nerve catheter placement: A randomised controlled trial

BACKGROUND Ultrasound-guided nerve blocks have become the standard when performing regional nerve blocks in anaesthesia. Infiniti Plus (CIVCO Medical Solutions, Kalona, Iowa, USA) is a needle guide that has been recently developed to help clinicians in performing ultrasound-guided nerve blocks. OBJECTIVES We tested the hypothesis that femoral nerve catheter placement carried out with the Infiniti Plus needle guide will be quicker to perform than without the Infiniti Plus. Secondary aims were to assess whether the Infiniti Plus needle guide decreased the number of block attempts and also whether it improved needle visibility. DESIGN A randomised, controlled trial. SETTING Cleveland Clinic, Cleveland, Ohio, USA. PATIENTS We enrolled adult patients having elective total knee arthroplasty with a femoral nerve block and femoral nerve catheter. Patients, who were pregnant or those who had preexisting neuropathy involving the surgical limb, coagulopathy, infection at the block site or allergy to local anaesthetics were excluded. INTERVENTIONS Patients were randomised into two groups to receive the ultrasound-guided femoral nerve catheter placement with or without the Infiniti Plus needle guide. MAIN OUTCOME MEASURES The time taken to place the femoral nerve catheter, the number of attempts, the success rate and needle visibility were recorded. We used an overall &agr; of 0.05 for both the primary and secondary analyses; the secondary analyses were Bonferroni corrected to control for multiple comparisons. RESULT The median (interquartile range Q1 to Q3) time to perform the femoral nerve catheter placement was 118 (100 to 150) s with Infiniti Plus and 177 (130 to 236) s without Infiniti Plus. Infiniti Plus significantly reduced the time spent performing femoral nerve catheterisation, with estimated ratio of means [(95% confidence interval), P value] of 0.67 [(0.60 to 0.75), P < 0.001] with Infiniti Plus compared with no Infiniti Plus. However, Infiniti Plus had no effect on the odds of a successful femoral nerve catheter placement, number of attempts or percentage of perfect needle visibility. CONCLUSION We found that the use of Infiniti Plus decreased the median time to successfully place a femoral nerve catheter by 33% compared with not using Infiniti Plus. This difference may be more apparent to clinicians undertaking this procedure less often or by those in training as our team was very experienced, had been trained in the technique and was working in a hospital with a large caseload. TRIAL REGISTRATION Clinicaltrials.gov identifier: NCT02080481.

Pharmacology: General Concepts

Medicine is intimately associated with a thorough understanding of clinical pharmacology. Many drugs have been discovered by observing natural materials—for example, plants—and their effects on animals. The physical effect of a drug, either positive or negative, can be observed without the knowledge of its mechanism of action. Modern drug discovery takes a different approach. Starting with a hypothesis that a certain protein is implicated in a disease, small molecules are screened for targeting the protein for the therapeutic effect; these are ultimately tested for a desired effect in basic science and clinical trials. The study of the interaction of the drug with the physiology of the body is the basis of clinical pharmacology.

Epidural compared with non-epidural analgesia and cardiopulmonary complications after colectomy: A retrospective cohort study of 20,880 patients using a national quality database

STUDY OBJECTIVE Epidural analgesia may be associated with fewer postoperative complications and is associated with improved survival after colon cancer resection. This study used the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) to assess any association between epidural analgesia (versus non-epidural) and complications after colectomy. DESIGN Retrospective cohort study. SETTING 603 hospitals in the United States reporting data to NSQIP. PATIENTS From 2014-15 data, 4176 patients undergoing colectomy with records indicating epidural analgesia were matched 1:4 via propensity scores to 16,704 patients without. INTERVENTIONS None (observational study). MEASUREMENTS Primarily, we assessed the association between epidural analgesia and a composite of cardiopulmonary complications using an average relative effect generalized estimating equations model. Secondary outcomes included neurologic, renal, and surgical complications and length of hospitalization. Sensitivity analyses repeated the analyses on a subgroup of only open colectomies. MAIN RESULTS We found no association between epidural analgesia and the primary outcome: average relative effect (95% CI) 0.87 (0.68, 1.11); P = 0.25. We found no significant associations with any secondary outcomes. In the 8005 open colectomies, however, there was a significant association between epidural analgesia and fewer cardiopulmonary complications (average relative effect odds ratio [95% CI] of 0.58 [0.35, 0.95]; P = 0.03) and shortened hospital stay (HR for time to discharge [98.75% CI] of 1.10 [1.02, 1.18]; P < 0.001). CONCLUSIONS We found no overall association between epidural analgesia and reduced complications after colectomy. In open colectomies, however, epidural analgesia was associated with fewer cardiopulmonary complications and shorter hospitalization. This may inform analgesic choice when planning open colectomy.