Coimbatore Srinivas

Technical report: Analysis of citrated blood with thromboelastography: comparison with fresh blood samples

Purpose: Thromboelastography (TEG) evaluates the viscoelastic properties of whole blood to assess clot formation and hemostasis. When blood cannot be analyzed immediately, it is stored in citrated tubes to be analyzed after recalcification. In this study, we evaluated the results of TEG analysis performed on citrated blood and compared these results to values obtained from activated (kaolin and tissue factor) and non activated, fresh blood samples, obtained at various time intervals (one, two, and three hours).Methods: Four blood samples were collected from each of ten healthy volunteers. The following TEG analyses were performed on each sample: reaction time (r), k time (k), alpha angle (α), and maximum amplitude (MA). Studies were done using fresh, non citrated blood, obtained within five minutes of collection, and using citrated blood, one, two, and three hours after collection. Samples were analyzed, with and without activation, using kaolin and tissue factor.Results: Tissue factor activated and non activated, citrated samples had shorter r and k times (P=0.03,P=0.008,P<0.0001, andP<0.0001, respectively) and higher alpha angle and MA values (P<0.0001,P<0.0001,P=0.79, andP=0.03, respectively) compared to fresh, non citrated samples. These findings were consistent with a hypercoagulable state. Conversely, citrated samples, activated with kaolin, yielded results similar to those obtained from fresh, non citrated samples. The TEG measurements were similar among citrated samples stored from one to three hours.Conclusions: Our results demonstrate that TEG measures, performed on citrated blood samples, yield results that are consistent with a hyperocoagulable state. Using kaolin to activate citrated samples, on the other hand, yields results similar to those obtained from non citrated, fresh blood samples.RésuméObjectif: La thromboélastographie (TEG) évalue les propriétés viscoélastiques du sang complet afin d’évaluer la formation de caillots et l’hémostase. Lorsque le sang ne peut pas être immédiatement analysé, il est stocké dans des tubes citratés afin d’être analysé après recalcification. Dans cette étude, nous avons évalué les résultats d’analyse TEG obtenus sur des échantillons de sang citraté et avons comparé ces résultats aux valeurs obtenues à partir d’échantillons de sang frais, activé (kaolin et facteur tissulaire) et non activé, lesquels avaient été obtenus à différents intervalles de temps (une, deux et trois heures).Méthode: Dix volontaires sains ont chacun donné quatre échantillons de sang. Les analyses TEG suivantes ont été effectuées sur chaque échantillon : temps de réaction (r), temps k (k), angle alpha (α) et amplitude maximale (MA). Des études ont été faites avec du sang frais et non citraté dans les cinq minutes suivant son obtention, ainsi qu’avec du sang citraté une, deux et trois heures après la collecte. Les échantillons ont été analysés avec ou sans activation à l’aide de kaolin et de facteur tissulaire.Résultats: Les échantillons citratés activés et non activés avec le facteur tissulaire ont présenté des temps r et k (P=0,03, P=0,008, P<0,0001, et P<0,0001, respectivement) plus courts ainsi qu’un angle alpha et des valeurs MA plus élevés (P<0,0001, P<0,0001, P=0,79, et P=0,03, respectivement) que les échantillons frais et non citratés. Ces résultats coïncident avec un état hypercoagulable. En revanche, les échantillons citratés activés avec kaolin ont donné des résultats similaires à ceux obtenus à partir d’échantillons frais non citratés. Les mesures TEG étaient semblables pour les échantillons citratés stockés de une à trois heures.Conclusion: Nos résultats démontrent que les mesures TEG, effectuées sur des échantillons de sang citratés, donnent des résultats qui coïncident avec un état hypercoagulable. L’utilisation de kaolin pour activer des échantillons citratés, en revanche, donne des résultats similaires à ceux obtenus d’échantillons de sang frais non citraté.

Transversus abdominis plane (TAP) catheters inserted under direct vision in the donor site following free DIEP and MS-TRAM breast reconstruction: A prospective cohort study of 45 patients

INTRODUCTION The transversus abdominis plane (TAP) block is a peripheral nerve block of T6-L1 intercostal nerves of the abdominal wall. The purpose of this study was to evaluate the usefulness of intermittent TAP blockade for the first two postoperative days following free muscle sparing-transverse rectus abdominis muscle (MS-TRAM) or deep inferior epigastric perforator (DIEP) flap reconstruction of the breast. Therapeutic--Level II evidence. MATERIAL AND METHODS This prospective cohort consisted of 45 consecutive patients who underwent DIEP or MS-TRAM free-flap breast reconstruction. Intra-operatively, a multi-orifice epidural catheter was inserted under direct vision into the TAP. Ten millilitres of 0.25% bupivacaine was injected into each TAP catheter every 12 h until removal on day 3. The control group consisted of 80 consecutive patients who underwent free MS-TRAM or DIEP free-flap breast reconstructions by the same two surgeons without TAP block. Postoperatively, both groups had patient-controlled analgesia (PCA) and the primary outcome was intravenous (IV) PCA opioid consumption in the first 48 h. RESULTS There were no complications associated with using TAP catheters. The 48-h PCA-delivered opioid requirement was significantly less (p<0.001) in the TAP block group (17.10±17.23 mg IV morphine equivalent) compared to the control group (48.44±39.53 mg). CONCLUSION Intermittent delivery of bupivacaine through the TAP block significantly reduced postoperative parenteral opioid requirements following free MS-TRAM or DIEP flap reconstruction of the breast. This is the first report of the TAP block being inserted under direct vision to provide postoperative analgesia at the abdominal flap donor site following microsurgical breast reconstruction.

Massive haemorrhage in liver transplantation: Consequences, prediction and management

From its inception the success of liver transplantation has been associated with massive blood loss. Massive transfusion is classically defined as > 10 units of red blood cells within 24 h, but describing transfusion rates over a shorter period of time may reduce the potential for survival bias. Both massive haemorrhage and transfusion are associated with increased risk of mortality and morbidity (need for dialysis/surgical site infection) following liver transplantation although causality is difficult to prove due to the observational design of most trials. The blood loss associated with liver transplantation is multifactorial. Portal hypertension secondary to cirrhosis results in extensive collateral circulation, which can bleed during hepatectomy particular if portal pressures are increased. Avoiding volume loading and maintenance of a low central venous pressure together with the use of vasopressors have been shown to reduce blood loss and transfusion during liver transplantation, but may increase the risk of renal impairment post-operatively. Coagulation defects may be present pre-transplant, but haemostasis is often re-balanced due to a deficit in both pro- and anti-coagulation factors. Further derangement of haemostasis may develop in the anhepatic and neohepatic phases due to absent hepatic metabolic function, hyperfibrinolysis and platelet sequestration in the donor liver. Point-of-care tests of coagulation such as the viscoelastic tests rotation thromboelastometry/thromboelastometry allow and more accurate and rapid assessment of these derangements in coagulation and guide the use of factor replacement and antifibrinolytics. Transfusion protocols guided by these tests have been shown to reduce transfusion rates compared with conventional coagulation tests, but have not shown improvements in mortality or morbidity. Pre-operative factors associated with massive transfusion include previous surgery, re-do transplantation, the aetiology and severity of liver disease. Intra-operatively the use of piggy-back technique and avoiding veno-veno bypass has been shown to reduced blood loss.

The Effectiveness and Safety of Tranexamic Acid in Orthotopic Liver Transplantation Clinical Practice: A Propensity Score Matched Cohort Study

Background Randomized trials have demonstrated the efficacy of tranexamic acid (TXA) in reducing blood loss and transfusion requirements during liver transplantation. However, clinical utilization is limited due to a perceived lack of generalizable effectiveness and concerns regarding its thromboembolic risks. The aim of this study was to describe the clinical use of TXA and to provide a pragmatic reappraisal of its effectiveness and safety. Methods After ethics approval, data were collected from 1799 consecutive liver transplant recipients between January 1, 2002, and December 31, 2015, using retrospectively collected electronic databases. Propensity matching was used to account for confounders of transfusion and thrombotic risk. Exposure was defined as a total TXA dose greater than 10 mg/kg for 50% of the operative duration. Results After propensity matching, 367 unique pairs were well balanced in terms of all measured covariates. In the matched pairs, patients exposed to TXA received less red blood cell (3 [0, 6] vs 4 [1, 7] P = 0.003) and frozen plasma (6 [2, 10] vs 6 [2, 12], P = 0.032) transfusions. There were no differences in thromboembolic events between the groups (22 [6.0%] vs 36 [9.8%]). Conclusions TXA appears effective in reducing red blood cell transfusion requirements without increasing the risk of thromboembolic events across a wide variety of liver transplant recipients, including those at low risk of bleeding or high risk of thromboembolic complications. We did not detect evidence of an increased risk of thrombotic complications with TXA exposure.

Chronic Postsurgical Pain Outcomes in Breast Reconstruction Patients Receiving Perioperative Transversus Abdominis Plane Catheters at the Donor Site: A Prospective Cohort Follow-up Study

Chronic postsurgical pain (CPSP) is a debilitating and costly condition. Risk factors for CPSP after autologous breast reconstruction have not been clearly established. Previously, we demonstrated that transversus abdominis plane (TAP) catheters delivering intermittent local anesthetic reduced postoperative morphine consumption. This prospective follow‐up study aimed to (1) compare the incidence of CPSP after autologous breast reconstruction between patients who received postoperative intermittent TAP catheters with bupivacaine or saline boluses and (2) assess the factors that contribute to the development and maintenance of CPSP in this study cohort.

Cardiovascular complications after non-cardiac surgery

Cardiac complications are common after non‐cardiac surgery. Peri‐operative myocardial infarction occurs in 3% of patients undergoing major surgery. Recently, however, our understanding of the epidemiology of these cardiac events has broadened to include myocardial injury after non‐cardiac surgery, diagnosed by an asymptomatic troponin rise, which also carries a poor prognosis. We review the causation of myocardial injury after non‐cardiac surgery, with potential for prevention and treatment, based on currently available international guidelines and landmark studies. Postoperative arrhythmias are also a frequent cause of morbidity, with atrial fibrillation and QT‐prolongation having specific relevance to the peri‐operative period. Postoperative systolic heart failure is rare outside of myocardial infarction or cardiac surgery, but the impact of pre‐operative diastolic dysfunction and its ability to cause postoperative heart failure is increasingly recognised. The latest evidence regarding diastolic dysfunction and the impact on non‐cardiac surgery are examined to help guide fluid management for the non‐cardiac anaesthetist.

Anesthetic management of a patient with arginase deficiency undergoing liver transplantation.

A 20-year-old female underwent orthotopic liver transplantation for arginase deficiency, a urea cycle disorder. A hyperammonemic state was prevented by the administration of lipid and carbohydrate substrate and avoidance of protein loading (including human albumin) and prolonged fasting. Caval cross-clamping may have been tolerated poorly owing to the potential interaction between hyperargininemia (a nitric oxide precursor) and the lack of collateral venous drainage. Ammonia and arginine levels improved in parallel with hepatic function after reperfusion of the hepatic graft.

A Case Report of Paradoxical Air Embolism Caused by Intrapulmonary Shunting During Liver Transplantation

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Neuroprotection during aortic surgery

Neurological injury is a major limitation of aortic surgery, whether it involves spinal cord injury following intervention to the thoracoabdominal aorta, or stroke following surgery on the arch and ascending aorta. Despite an extensive body of literature and various proposals, a completely effective strategy to prevent or treat neurological injury remains elusive. In this article, we summarise the evidence for established and emerging strategies, and review current concepts in pathophysiology and risk assessment as they relate to neurological injury.

In-hospital opioid consumption, but not pain intensity scores, predict 6-month levels of pain catastrophizing following hepatic resection: a trajectory analysis

The study aims were to model acute pain intensity and opioid consumption trajectories up to 72 hr after open hepatic resection, identify predictors of trajectory membership and examine the association between trajectory memberships and 6‐month pain and psychological outcomes. This is a long‐term analysis of a published randomized controlled trial on the impact of medial open transversus abdominis plane catheters on post‐operative outcomes.