Journal Club 2016-17

    Dr. Makaryus gave a terrific review of the meaning of a P value so we can all have a better understanding of it. The p-value is defined as the probability of obtaining a result equal to or "more extreme" than what was actually observed, when the null hypothesis is true. It is important to remember that this statistical measure is distinct from clinical significance.

Dr. Llenes gave an excellent review of the article by the Postoperative Visual Loss Study group. Visual Loss after spinal fusion surgery is commonly caused by ischemic optic neuropathy (ION). In this case control study, 80 patients with ION were compared to 315 matched control subjects. ION-dependent risk factors were male sex, obesity, wilson frame, long surgery duration, larger blood loss and lower percent colloid given. This was the first study to assess ION risk factors in a larger multicenter case control with detailed operative data. The study concluded that preventative strategies are the only option to reduce the incidence of visual loss. Maneuvers to keep the head at or higher than the heart to reduce venous congestion in the head is a recommendation from the ASA practice advisory for perioperative vision loss. Also minimization the prone position and maximizing hemostasis/minimizing EBL, and use of colloid along with crystalloid may decrease risk of ION. Prediction tables for ION based on this study may help inform patients, surgeons and anesthesiologists of the relative risk for patients developing ION and help guide decisions.

Dr. Gonzales gave a concise review of the Rubin et al paper. The object of this study was to identify trends and risk factors for ION incidence during spinal fusion using a large, nationwide hospital database. Perioperatve ION in spinal fusion decreased 2.7-fold between 1998-2012. Older age, male sex, transfusion history and obesity increased the risk. Although there is an ASA practice advisory aimed to increasing awareness and of ION and to help guide patient management, the study could not determine if the advisory statement had a role in the changing incidence of ION. Spine surgery is increasingly done with minimally invasive surgery but there was no code to identify the procedure prior 2013. There are limitations to this study. There is not enough data to asses the accuracy of coding complication such as ION . There could be over- or under-coding. Further studies of databases that contain more pertinent intraoperative info may help determine whether perioperative surgical and anesthetic practice has been modified according to national practice advisories. We discussed the importance of informed consent from surgeons and anesthesiologists since this is a devastating complication that patients should be made aware of.

    Dr. Makaryus reviewed Meta Analysis. The different types of studies that might be included in a meta-analysis are: case controlled, case selection and cohort. The main objectives of a meta-analysis are: to summarize and integrate results from a number of individual studies, analyze their differences, determine whether additional studies are needed and to generate new hypotheses. Problems associated with meta-analysis are: publication bias , search bias in the identification phase, and selection bias in the selection phase.

Dr. Smith reviewed the Mooney et al meta-analysis. It concluded that estimated GFR rate less than 60 ml/min was associated with a 3-fold increase in 30 day mortality. There was also a relationship between eGFR and both short and long term prognosis after cardiac and vascular surgery. Because renal function declines with age, and is associated with conditions such as DM, dyslipidemia, and HTN, the role of GFR per se is difficult to determine. One limitation of this meta-analysis is that most of the published studies dealt with cardiac surgery only. Many studies were retrospective and reported only all-cause mortality. In conclusion, the data supports use of eGFR as an indicator of the risk of postoperative complications after cardiac and vascular surgery. We discussed how other markers might be used perioperatively to help predict patient outcome.

Dr. Sharma reviewed the Myles et al paper. It found that the increased risk of PONV with nitrous oxide is nearly eliminated by antiemetic prophylaxsis. Severe PONV occurs in 10% of cases. It results in postoperative fever, poor recovery and prolonged hospital stay. Nitrous oxide, an anesthetic that has been in use for more than 150 years, is now falling out of favor. However, there are situations in which it is appropriate to use it in the OR.

   Enhanced recovery after surgery (ERAS) and modern perioperative care has enabled us to take a closer look at IVF treatment. Dr. Fischl reported on Srinivas et al. They studied 85 elective colectomy patients randomized for goal-directed fluid therapy (GDFT) vs. fluid restriction. GDFT did not provide any clinical benefit to patients. Cannesson et al. found that respiratory arterial pressure variation (PPV) is the best predictor of fluid responsiveness in mechanically ventilated patients during general anesthesia. It was surmised that a gray zone statistical approach to decision-making can increase the use of diagnostic measures such as PPV to predict fluid responsiveness. In this four center study of 413 patients, the gray zone approach of PPV was inconclusive in 25% of patients. There was also interesting discussion about the use of preop carbohydrate loading. A problem is that we do not really know how much of it is drunk by patients.

Dr. Thalappillil reviewed the paper by Pearse et al. Randomization of the 734 high risk patients included assignment to the Cardiac Output-guided hemodynamic therapy Algorithm for IV fluid and treatment with inotrope infusion of dopexamine. Dopexamine is a synthetic analogue of dopamine used in the UK. It is a beta2 agonist with no alpha effects. This study compared the Cardiac Output-guided hemodynamic therapy Algorithm with usual care and found there was no reduction in composite outcome of complications or 30 day mortality. These data included an updated meta-analysis found the intervention was associated with a reduction in complication rates. There was discussion regarding an editorial to this paper written by Dr. Elliott Bennett-Guerrero. The Gan et al paper was also discussed. This was a prospective randomized study to assess the effect of Goal directed intraoperative fluid therpy guided by EDM on the length of postoperative stay. The esophageal doppler monitor (EDM) is a minimally invasive device that gives rapid continuous estimation of cardiac output. The corrected flow time (FTc) is a good index of systemic vascular resistance and sensitive to changes in left ventricular preload. There were 100 ASA I-III patients undergoing major elective general, urologic or gynecologic surgery with anticipated EBL >500ml. In the control group, the EDM monitor was turned away from the anesthesia provider. Hypovolemia during periop period is associated with an increase in postoperative nausea /vomiting /organ dysfunction and long hospital stay. Dr. Bennett-Guerrero's 1999 article in Anesth Analg found that gastrointestinal dysfunction was the most common complication in patients undergoing moderate-risk surgery. The Gan study inferred that improved perfusion of the gastric mucosa from additional fluid could have resulted in less postop n/v. There were some limitations: bias due to the inability to blind the anesthesiologists in the treatment group. Differences in the groups could be attributed to the different types of fluid given. It was found that (GDFT) goal directed fluid tx with 6% hetastarch had improved patient outcomes and slight reduction in length of hospital stay. In the discussion, it was noted that the largest predictor of how the patient does is the anesthetist. IVF administration can range from 840ml- 5500ml for similarly timed procedures in patients of the same weight and same EBL. It was also noted that one's response to the monitor is more important than just using the monitor. In the future, if we don't police ourselves, outside forces will dictate that using a monitor will improve outcomes; in order to justify the cost of the monitor. There were also comments on a new monitor recently seen at the ASA - a nociceptive monitor which might, in future versions, help determine amount of opiate to be given. We hope that anesthesiologists will have a say in which monitors will be helpful in patients and are necessary to have in the OR.

   Dr. Minxi Weng gave a concise review of the Saver et al article. The conclusion from this meta-analysis was that for patients with large vessel ischemic stroke, early treatment with endovascular thrombectomy and medical therapy compared with medical therapy alone was associated with lower degrees of disability at 3 months.

Dr. Than Kim gave an excellent review of the Schonenberger et al article. In this trial, conscious sedation compared to general anesthesia did not result in greater improvement of neurological status at 24 hours. Study findings did not find an advantage for the use of conscious sedation.

   Dr. Josma reviewed the Bulka et al article. This study from Vanderbilt University, used their NSQIP database to compare a) 1455 surgical patients who received an intermediate-acting nondepolarizing NMBA to 1455 propensity score-matched patients who did not and b) 1320 patients who received a NMBA and reversal with neostigmine to 1320 propensity score-matched cases who did not receive reversal. They found that intraoperative use of intermediate NMBA is associated with pneumonia and non-reversal is also associated with an increased risk of pneumonia. Because this was an observational study, causality cannot be established. During the discussion, that Dr Abola mentioned that if a patient truly needs paralysis and if a NMBA is given then a reversal agent should be used. Dr Rosenfeld stated that this is the first study that looked at the specific issue of pneumonia and used specific NSQIP data of pneumonia. It was noted that our use of twitch monitors does not allow us to distinguish between 0.4-0.9 for T1. Acceleromyographic monitoring is more sensitive but it is not routinely used at hospitals.

Dr. Georges reviewed the Brueckmann et al article. This study found that after abdominal surgery, reversal with sugammadex eliminated residual blockade in the PACU and shortened the time to readiness for discharge from OR. The study did not find any evidence that sugammadex is associated with any respiratory complications. In contrast, neostigmine impairs the upper dilator muscles. This study did not have sufficient power to identify differences in incidence of postoperative respiratory complications. Important aspects of sugammedex were discussed. It should not be given to ESRD patients and should not be given concurrently with Zofran. If a patient is taking an oral contraceptive, then they should use another means of protection after having had sugammedex.

   Dr. Hua gave a concise review of the Ajiboye et al article. This study from UCLA was a retrospective database study evaluating the trends in the use of interoperative neuromonitoring (ION) for anterior cervical discectomy and fusion (ACDF) surgery in USA. They assessed incidence of neuro injuries after ACDF with and without ION. This study reported a significant decrease in the use of ION for ACDF. It was also noted that use of ION doesn't decrease the rate of postoperative neuro complications for ACDF. They concluded that the utility of routine ION for ACDF is questionable. Dr. Stephens noted that he uses ION frequently. It was a lively discussion using this new JC format.

Dr. Khmara gave an excellent review of the Krishnakumar and Srivatsa article. The authors did a prospective analysis of neuromonitoring (SSEP and TcMEP) in scoliosis surgery at a tertiary care spine center in India. They found that the use of the upper limb leads could help identify malpositioned or malfunctioning of leads and thus eliminate false positive results. ION increases the safety in scoliosis corrective surgeries with a high sensitivity and specificity. There was also another dynamic discussion in the group of this article. Dr Azim explained that volatile anesthetics can decrease amplitude and increase latency of the ION signals. Thus, TIVA is preferred. For SSEP, volatile anesthetics at ½ MAC can be used. We reviewed the different types of ION. The purpose of measuring intraoperative evoked potentials is to monitor neural pathways so as to avoid iatrogenic injury to the nervous system. Sensory evoked potentials (SEPs) evaluate the integrity of ascending sensory tracts while motor evoked potentials (MEPs) deal with the functionality of descending motor pathways.

Everyone appeared to enjoy our new format of the journal club (Thx Dr Khmara). This technique of "think, pair, share" worked really well. In the small groups, we allowed about 10 min to think about and discuss some particular questions. Then, the small groups shared this info with everyone when that question came up.