Bhiken I. Naik

Rotational thromboelastometry-guided blood product management in major spine surgery

OBJECT Major spinal surgery in adult patients is often associated with significant intraoperative blood loss. Rotational thromboelastometry (ROTEM) is a functional viscoelastometric method for real-time hemostasis testing. In this study, the authors sought to characterize the coagulation abnormalities encountered in spine surgery and determine whether a ROTEM-guided, protocol-based approach to transfusion reduced blood loss and blood product use and cost. METHODS A hospital database was used to identify patients who had undergone adult deformity correction spine surgery with ROTEM-guided therapy. All patients who received ROTEM-guided therapy (ROTEM group) were matched with historical cohorts whose coagulation status had not been evaluated with ROTEM but who were treated using a conventional clinical and point-of-care laboratory approach to transfusion (Conventional group). Both groups were subdivided into 2 groups based on whether they had received intraoperative tranexamic acid (TXA), the only coagulation-modifying medication administered intraoperatively during the study period. In the ROTEM group, 26 patients received TXA (ROTEM-TXA group) and 24 did not (ROTEM-nonTXA group). Demographic, surgical, laboratory, and perioperative transfusion data were recorded. Data were analyzed by rank permutation test, adapted for the 1:2 ROTEM-to-Conventional matching structure, with p < 0.05 considered significant. RESULTS Comparison of the 2 groups in which TXA was used showed significantly less fresh-frozen plasma (FFP) use in the ROTEM-TXA group than in the Conventional-TXA group (median 0 units [range 0-4 units] vs 2.5 units [range 0-13 units], p < 0.0002) but significantly more cryoprecipitate use (median 1 unit [range 0-4 units] in the ROTEM-TXA group vs 0 units [range 0-2 units] in the Conventional-TXA group, p < 0.05), with a nonsignificant reduction in blood loss (median 2.6 L [range 0.9-5.4 L] in the ROTEM-TXA group vs 2.9 L [0.7-7.0 L] in the Conventional-TXA group, p = 0.21). In the 2 groups in which TXA was not used, the ROTEM-nonTXA group showed significantly less blood loss than the Conventional-nonTXA group (median 1 L [range 0.2-6.0 L] vs 1.5 L [range 1.0-4.5 L], p = 0.0005), with a trend toward less transfusion of packed red blood cells (pRBC) (median 0 units [range 0-4 units] vs 1 unit [range 0-9 units], p = 0.09]. Cryoprecipitate use was increased and FFP use decreased in response to ROTEM analysis identifying hypofibrinogenemia as a major contributor to ongoing coagulopathy. CONCLUSIONS In major spine surgery, ROTEM-guided transfusion allows for standardization of transfusion practices and early identification and treatment of hypofibrinogenemia. Hypofibrinogenemia is an important cause of the coagulopathy encountered during these procedures and aggressive management of this complication is associated with less intraoperative blood loss, reduced transfusion requirements, and decreased transfusion-related cost.

Management of One-lung Ventilation: Impact of Tidal Volume on Complications after Thoracic Surgery.

Background:The use of lung-protective ventilation (LPV) strategies may minimize iatrogenic lung injury in surgical patients. However, the identification of an ideal LPV strategy, particularly during one-lung ventilation (OLV), remains elusive. This study examines the role of ventilator management during OLV and its impact on clinical outcomes. Methods:Data were retrospectively collected from the hospital electronic medical record and the Society of Thoracic Surgery database for subjects undergoing thoracic surgery with OLV between 2012 and 2014. Mean tidal volume (VT) during two-lung ventilation and OLV and ventilator driving pressure (&Dgr;P) (plateau pressure − positive end-expiratory pressure [PEEP]) were analyzed for the 1,019 cases that met the inclusion criteria. Associations between ventilator parameters and clinical outcomes were examined by multivariate linear regression. Results:After the initiation of OLV, 73.3, 43.3, 18.8, and 7.2% of patients received VT greater than 5, 6, 7, and 8 ml/kg predicted body weight, respectively. One hundred and eighty-four primary and 288 secondary outcome events were recorded. In multivariate logistic regression modeling, VT was inversely related to the incidence of respiratory complications (odds ratio, 0.837; 95% CI, 0.729 to 0.958), while &Dgr;P predicted the development of major morbidity when modeled with VT (odds ratio, 1.034; 95% CI, 1.001 to 1.068). Conclusions:Low VT per se (i.e., in the absence of sufficient PEEP) has not been unambiguously demonstrated to be beneficial. The authors found that a large proportion of patients continue to receive high VT during OLV and that VT was inversely related to the incidence of respiratory complications and major postoperative morbidity. While low (physiologically appropriate) VT is an important component of an LPV strategy for surgical patients during OLV, current evidence suggests that, without adequate PEEP, low VT does not prevent postoperative respiratory complications. Thus, use of physiologic VT may represent a necessary, but not independently sufficient, component of LPV.

Incidence and risk factors for acute kidney injury after spine surgery using the RIFLE classification.

OBJECT Earlier definitions of acute renal failure are not sensitive in identifying milder forms of acute kidney injury (AKI). The authors hypothesized that by applying the RIFLE criteria for acute renal failure (Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage kidney disease) to thoracic and lumbar spine surgery, there would be a higher incidence of AKI. They also developed a model to predict the postoperative glomerular filtration rate (GFR). METHODS A hospital data repository was used to identify patients undergoing thoracic and/or lumbar spine surgery over a 5-year period (2006-2011). The lowest GFR in the first week after surgery was used to identify and categorize kidney injury if present. Risk factors were identified and a model was developed to predict postoperative GFR based on the defined risk factors. RESULTS A total of 726 patients were identified over the study period. The incidence of AKI was 3.9% (n = 28) based on the RIFLE classification with 23 patients in the risk category and 5 in the injury category. No patient was classified into the failure category or required renal replacement therapy. The baseline GFR in the non-AKI and AKI groups was 80 and 79.8 ml/min, respectively. After univariate analysis, only hypertension was associated with postoperative AKI (p = 0.02). A model was developed to predict the postoperative GFR. This model accounted for 64.4% of the variation in the postoperative GFRs (r(2) = 0.644). CONCLUSIONS The incidence of AKI in spine surgery is higher than previously reported, with all of the patients classified into either the risk or injury RIFLE categories. Because these categories have previously been shown to be associated with poor long-term outcomes, early recognition, management, and follow-up of these patients is important.

The Effect of Dexmedetomidine on Postoperative Opioid Consumption and Pain After Major Spine Surgery.

BACKGROUND:Adult deformity correction spine surgery can be associated with significant perioperative pain because of inflammatory, muscular, neuropathic, and postsurgical pain. &agr;-2 Agonists have intrinsic antinociceptive and antihyperalgesic properties that can potentially reduce both postoperative opioid consumption and pain. We hypothesized that intraoperative dexmedetomidine would reduce postoperative opioid consumption and improve pain scores in deformity correction spine surgery. METHODS:Patients undergoing >3 levels of thoracic and/or lumbar spine surgery were enrolled in this prospective randomized double-blind study to receive either dexmedetomidine (1 &mgr;g/kg load followed by a continuous infusion of 0.5 &mgr;g/kg/h) or saline. Both groups received a single dose of 0.2 mg/kg (ideal body weight) of methadone at the start of surgery. Intraoperative fentanyl was administered based on the clinical and hemodynamic signs suggestive of increased nociception. Postoperative analgesia was provided with a hydromorphone patient-controlled analgesia pump. Opioid consumption and pain scores were recorded at 24, 48, and 72 hours after surgery. RESULTS:One hundred forty-two participants were enrolled with 131 completing the study. There was no significant difference in demographics (age, sex, weight, and ASA physical status), percentage of participants with preoperative opioid use, and daily median opioid consumption between the groups. The study was terminated early after interim analysis. Intraoperative opioid use was reduced in the dexmedetomidine arm (placebo versus dexmedetomidine, median [25%–75% interquartile range]: 7 [3–15] vs 3.5 [0–11] mg morphine equivalents, P = 0.04) but not at 24 hours: 49 (30–78) vs 61 (34–77) mg morphine equivalents, P = 0.65, or 48 hours: 41 (28–68) vs 40 (23–64) mg morphine equivalents, P = 0.60, or 72 hours: 29 (15–59) vs 30 (14–46) mg morphine equivalents, P = 0.58. The Wilcoxon-Mann-Whitney odds are 1.11 with 97.06% confidence interval (0.71–1.76) for opioid consumption. No difference in pain score, as measured by the 11-point visual analog scale, was seen at 24 hours (placebo versus dexmedetomidine, median [25%–75% interquartile range]: 7 [5–7] vs 6 [4–7], P = 0.12) and 48 hours (5 [3–7] vs 5 [3–6], P = 0.65). There was an increased incidence of bradycardia (placebo: 37% vs dexmedetomidine: 59% P = 0.02) and phenylephrine use in the dexmedetomidine group (placebo: 59% versus dexmedetomidine: 78%, P = 0.03). CONCLUSIONS:Intraoperative dexmedetomidine does not reduce postoperative opioid consumption or improve pain scores after multilevel deformity correction spine surgery.

Post-Craniotomy Pain Management: Beyond Opioids

Craniotomy pain may be severe and is often undertreated. Pain management following craniotomy is a balancing act of achieving adequate analgesia but avoiding sedation, respiratory depression, hypercapnia, nausea and vomiting, and hypertension. Opioids are a first-line analgesic therapy; however, concern that opioid-related adverse effects (sedation, respiratory depression) may interfere with neurologic assessment and increase intracranial pressure has limited use of these drugs for intracranial surgery. Non-opioid analgesics avoid these effects and may be useful as part of a multimodal regimen for post-craniotomy pain. Regional scalp blocks, paracetamol, and non-steroidal anti-inflammatory drugs are beneficial in the early post-operative period. Recent studies suggest a role for novel analgesics: dexmedetomidine, gabapentinoids, and ketamine, though additional studies are necessary.

Hemodynamic monitoring devices: Putting it all together

Perioperative hemodynamic optimization of the high-risk surgical patient is associated with reduced postoperative morbidity and mortality. The hemodynamic parameters to be optimized (using goal-directed algorithms) encompass preload, contractility, afterload, volume responsiveness, and end-organ perfusion. Current hemodynamic monitors facilitate multi-modal monitoring of these macro-hemodynamic targets. This review focuses on the variety of invasive, minimally invasive, and noninvasive hemodynamic monitors available to the clinician.

Influence of catastrophizing, anxiety, and depression on in-hospital opioid consumption, pain, and quality of recovery after adult spine surgery

OBJECTIVE Perception of perioperative pain is influenced by various psychological factors. The aim of this study was to determine the impact of catastrophizing, anxiety, and depression on in-hospital opioid consumption, pain scores, and quality of recovery in adults who underwent spine surgery. METHODS Patients undergoing spine surgery were enrolled in this study, and the preoperatively completed questionnaires included the verbal rating scale (VRS), Pain Catastrophizing Scale (PCS), Hospital Anxiety and Depression Scale (HADS), and Oswestry Disability Index (ODI). Quality of recovery was assessed using the 40-item Quality of Recovery questionnaire (QoR40). Opioid consumption and pain scores according to the VRS were recorded daily until discharge. RESULTS One hundred thirty-nine patients were recruited for the study, and 101 completed the QoR40 assessment postoperatively. Patients with higher catastrophizing scores were more likely to have higher maximum pain scores postoperatively (estimate: 0.03, SE: 0.01, p = 0.02), without increased opioid use (estimate: 0.44, SE: 0.27, p = 0.11). Preoperative anxiety (estimate: 1.18, SE: 0.65, p = 0.07) and depression scores (estimate: 1.06, SE: 0.71, p = 0.14) did not correlate with increased postoperative opioid use; however, patients with higher preoperative depression scores had lower quality of recovery after surgery (estimate: -1.9, SE: 0.56, p < 0.001). CONCLUSIONS Catastrophizing, anxiety, and depression play important roles in modulating postoperative pain. Preoperative evaluation of these factors, utilizing a validated tool, helps to identify patients at risk. This might allow for earlier psychological intervention that could reduce pain severity and improve the quality of recovery.

SEER Sonorheometry Versus Rotational Thromboelastometry in Large Volume Blood Loss Spine Surgery.

BACKGROUND:Sonic estimation of elasticity via resonance (SEER) sonorheometry is a novel technology that uses acoustic deformation of the developing clot to measure its viscoelastic properties and extract functional measures of coagulation. Multilevel spine surgery is associated with significant perioperative blood loss, and coagulopathy occurs frequently. The aim of this study was to correlate SEER sonorheometry results with those of equivalent rotation thromboelastometry (ROTEM) and laboratory parameters obtained during deformity correction spine surgery. METHODS:Four independent SEER sonorheometry hemostatic indices (clot time, clot stiffness, fibrinogen, and platelet contribution) were measured. SEER sonorheometry clot time, using kaolin as an activator, was correlated with ROTEM intrinsic temogram clotting time and the activated partial thromboplastin time. For clot stiffness, thromboplastin was the primary activator, and this was correlated against ROTEM external temogram amplitude at 10 minutes (A10). The assay for the fibrinogen contribution was similar to clot stiffness, but abciximab was added to inhibit platelet function. The fibrinogen contribution assay was correlated with the ROTEM fibrinogen temogram A10. Finally, the SEER sonorheometry platelet contribution was calculated by subtracting the fibrinogen contribution from the clot stiffness. This variable was correlated with both absolute platelet counts, and ROTEM determined clot elasticity attributable to platelets. RESULTS:Fifty-one patients were enrolled in this prospective observational study. SEER sonorheometry clot stiffness, fibrinogen, and platelet contribution had a very strong correlation with ROTEM external temogram A10 (rs = .92; 99% confidence interval, .85–.96), fibrinogen temogram A10 (rs = .90; 99% confidence interval, .83–.93), and ROTEM-determined clot elasticity attributable to platelets (rs = .89; 99% confidence interval, .80–.95). SEER sonorheometry clot time exhibited moderate correlation with ROTEM intrinsic temogram clotting time (rs = .62; 99% confidence interval, .44–.77) and very weak correlation with activated partial thromboplastin time (rs = .33; 99% confidence interval, .10–.51). CONCLUSIONS:SEER sonorheometry demonstrates very strong correlation with ROTEM for determining clot stiffness and assessing fibrinogen and platelet contribution to clot strength in major spine surgery. An advantage of SEER sonorheometry is direct measurement of clot elasticity with no need to transform amplitude oscillation to elasticity.

Perioperative Management of Adult Patients With External Ventricular and Lumbar Drains: Guidelines From the Society for Neuroscience in Anesthesiology and Critical Care.

External ventricular drains and lumbar drains are commonly used to divert cerebrospinal fluid and to measure cerebrospinal fluid pressure. Although commonly encountered in the perioperative setting and critical for the care of neurosurgical patients, there are no guidelines regarding their management in the perioperative period. To address this gap in the literature, The Society for Neuroscience in Anesthesiology & Critical Care tasked an expert group to generate evidence-based guidelines. The document generated targets clinicians involved in perioperative care of patients with indwelling external ventricular and lumbar drains.

Haptoglobin 2‐2 Phenotype Is Associated With Increased Acute Kidney Injury After Elective Cardiac Surgery in Patients With Diabetes Mellitus

Background Recent studies reported an association between the 2‐2 phenotype of haptoglobin (Hp 2‐2) and increased cardiorenal morbidity in nonsurgical diabetic patients. Our goal was to determine whether the Hp 2‐2 phenotype was associated with acute kidney injury (AKI) after elective cardiac surgery in patients with diabetes mellitus. Methods and Results We prospectively enrolled 99 diabetic patients requiring elective cardiac surgery with cardiopulmonary bypass. Haptoglobin phenotypes were determined by gel electrophoresis. Cell‐free hemoglobin, haptoglobin, and total serum bilirubin were quantified as hemolysis markers. The primary outcome was postoperative AKI, as defined by the Acute Kidney Injury Network classification. The incidence of AKI was significantly higher in Hp 2‐2 patients compared with patients without this phenotype (non–Hp–2‐2; 55.6% versus 27%, P<0.01). The need for renal replacement therapy was also significantly higher in the Hp 2‐2 group (5 patients versus 1 patient, P=0.02). Thirty‐day mortality (3 versus 0 patients, P=0.04) and 1‐year mortality (5 versus 0 patients, P<0.01) were also significantly higher in patients with the Hp 2‐2 phenotype. In multivariable analysis, Hp 2‐2 was an independent predictor of postoperative AKI (P=0.01; odds ratio: 4.17; 95% confidence interval, 1.35–12.48). Conclusions Hp 2‐2 phenotype is an independent predictor of postoperative AKI and is associated with decreased short and long‐term survival after cardiac surgery in patients with diabetes mellitus.