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BackgroundDespite the significant healthcare impact of acute kidney injury, little is known regarding prevention. Single-center data have implicated hypotension in developing postoperative acute kidney injury. The generalizability of this finding and the interaction between hypotension and baseline patient disease burden remain unknown. The authors sought to determine whether the association between intraoperative hypotension and acute kidney injury varies by preoperative risk.MethodsMajor noncardiac surgical procedures performed on adult patients across eight hospitals between 2008 and 2015 were reviewed. Derivation and validation cohorts were used, and cases were stratified into preoperative risk quartiles based upon comorbidities and surgical procedure. After preoperative risk stratification, associations between intraoperative hypotension and acute kidney injury were analyzed. Hypotension was defined as the lowest mean arterial pressure range achieved for more than 10 min; ranges were defined as absolute (mmHg) or relative (percentage of decrease from baseline).ResultsAmong 138,021 cases reviewed, 12,431 (9.0%) developed postoperative acute kidney injury. Major risk factors included anemia, estimated glomerular filtration rate, surgery type, American Society of Anesthesiologists Physical Status, and expected anesthesia duration. Using such factors and others for risk stratification, patients with low baseline risk demonstrated no associations between intraoperative hypotension and acute kidney injury. Patients with medium risk demonstrated associations between severe-range intraoperative hypotension (mean arterial pressure less than 50 mmHg) and acute kidney injury (adjusted odds ratio, 2.62; 95% CI, 1.65 to 4.16 in validation cohort). In patients with the highest risk, mild hypotension ranges (mean arterial pressure 55 to 59 mmHg) were associated with acute kidney injury (adjusted odds ratio, 1.34; 95% CI, 1.16 to 1.56). Compared with absolute hypotension, relative hypotension demonstrated weak associations with acute kidney injury not replicable in the validation cohort.ConclusionsAdult patients undergoing noncardiac surgery demonstrate varying associations with distinct levels of hypotension when stratified by preoperative risk factors. Specific levels of absolute hypotension, but not relative hypotension, are an important independent risk factor for acute kidney injury.Editor’s PerspectiveWhat We Already Know about This TopicWhat This Article Tells Us That Is New

EDITOR’S PERSPECTIVE What We Already Know about This Topic Dantrolene effectively treats malignant hyperthermia, but there are discrepant recommendations for dantrolene availability in facilities that stock succinylcholine for airway rescue but do not use volatile anesthetics. What This Article Tells Us That Is New The authors performed an analysis of data from three databases and a systematic literature review. Providers frequently use succinylcholine, including during difficult mask ventilation. Succinylcholine given without volatile anesthetics triggered 24 malignant hyperthermia events, 13 of which were treated with dantrolene. Fourteen patients experienced substantial complications, and one died. Delayed dantrolene treatment worsened patient outcomes. Background Although dantrolene effectively treats malignant hyperthermia (MH), discrepant recommendations exist concerning dantrolene availability. Whereas Malignant Hyperthermia Association of the United States guidelines state dantrolene must be available within 10 min of the decision to treat MH wherever volatile anesthetics or succinylcholine are administered, a Society for Ambulatory Anesthesia protocol permits Class B ambulatory facilities to stock succinylcholine for airway rescue without dantrolene. The authors investigated (1) succinylcholine use rates, including for airway rescue, in anesthetizing/sedating locations; (2) whether succinylcholine without volatile anesthetics triggers MH warranting dantrolene; and (3) the relationship between dantrolene administration and MH morbidity/mortality. Methods The authors performed focused analyses of the Multicenter Perioperative Outcomes Group (2005 through 2016), North American MH Registry (2013 through 2016), and Anesthesia Closed Claims Project (1970 through 2014) databases, as well as a systematic literature review (1987 through 2017). The authors used difficult mask ventilation (grades III and IV) as a surrogate for airway rescue. MH experts judged dantrolene treatment. For MH morbidity/mortality analyses, the authors included U.S. and Canadian cases that were fulminant or scored 20 or higher on the clinical grading scale and in which volatile anesthetics or succinylcholine were given. Results Among 6,368,356 queried outcomes cases, 246,904 (3.9%) received succinylcholine without volatile agents. Succinylcholine was used in 46% (n = 710) of grade IV mask ventilation cases (median dose, 100 mg, 1.2 mg/kg). Succinylcholine without volatile anesthetics triggered 24 MH cases, 13 requiring dantrolene. Among 310 anesthetic-triggered MH cases, morbidity was 20 to 37%. Treatment delay increased complications every 10 min, reaching 100% with a 50-min delay. Overall mortality was 1 to 10%; 15 U.S. patients died, including 4 after anesthetics in freestanding facilities. Conclusions Providers use succinylcholine commonly, including during difficult mask ventilation. Succinylcholine administered without volatile anesthetics may trigger MH events requiring dantrolene. Delayed dantrolene treatment increases the likelihood of MH complications. The data reported herein support stocking dantrolene wherever succinylcholine or volatile anesthetics may be used.

In 1984, the Anesthesia Closed Claims Project was formed by the American Society of Anesthesiologists (ASA) in response to sky-rocking insurance premiums, which had left many physicians nearly unable to afford professional liability insurance. Through the analysis of insurance company closed claims, several areas of anesthetic-related patient injury were identified and deemed the focus of this project with the goal of delivering “better” anesthetic care. Ultimately, this resulted in the formation of the Anesthesia Closed Claims Project and its attendant Registries, including the Postoperative Visual Loss (POVL) Registry, Anesthesia Awareness Registry, Obstructive Sleep Apnea (OSA) Death and Near Miss Registry, Neurologic Injury after Non-Supine Shoulder Surgery (NINS) Registry, and Pediatric Perioperative Cardiac Arrest (POCA) Registry. Additionally, this chapter attempts to give some guidance to practicing anesthesiologists on best practices to avoid such devastating consequences. While firm recommendations for rare events are difficult to make, a review of available information is presented here.

Background Limited data are available regarding the perioperative management of cardiac rhythm management devices (CRMDs) exposed to intraoperative electromagnetic interference. We postulated that implementation of a simple, standardized approach to CRMD management using our own institution's Pacing And Cardioverting Electronic Devices peri-Operative Protocol (the PACED-OP protocol) would be associated with a reduction in the amount of device reprogramming without an increase in CRMD-related complications. Methods Records of patients with CRMDs undergoing 497 consecutive surgical procedures were analyzed retrospectively. Roughly half (51%, n = 254) of these procedures occurred before implementation of the PACED-OP protocol, when patients were generally treated according to the American Society of Anesthesiologists' 2005 guidelines. These cases were compared to the remaining surgeries that occurred after implementation of the PACED-OP protocol. Records were screened for evidence of intraoperative CRMD malfunction that was directly associated with the use of electrocautery. Postoperative complications that could be indirectly or possibly linked to electrocautery-mediated CRMD malfunction were also identified. Results Implementation of the PACED-OP protocol was associated with a significant reduction in the odds of device reprogramming (adjusted odds ratio [aOR] 0.19, P

Posttraumatic coagulopathy is a major cause of morbidity. This prospective study evaluated the thrombelastography (TEG) system and PlateletMapping (Haemoscope Corporation, Niles, Ill) values posttrauma, and it correlated those values with transfusions and fatalities. After institutional review board approval, assays were performed on 161 trauma patients. One citrated blood sample was collected onsite (OS), and 1 citrate and 1 heparinized sample were collected within 1 h of arrival to the emergency department (ED). Paired and unpaired t-testing was performed for nominal data with chi square testing for categorical values. Except for a slight increase in clot strength (maximal amplitude (MA)), there were no significant changes from OS to the ED. None of the TEG parameters were significantly different for the 22 patients who required transfusion. PlateletMapping showed lower platelet adenosine diphosphate (ADP) responsiveness in patients who needed transfusions (MA = 22.7 +/- 17.1 vs MA = 35.7 +/- 19.3, P = 0.004) and a correlation of fibrinogen100 mg/dL with fatalities (P = 0.013). For the 14 fatalities, TEG reaction (R) time was 3703 +/- 11,618 versus 270 +/- 393 s (P =0.001), and MA was 46.4 +/- 22.4 versus 64.7 +/- 9.8 mm (P0.001). Hyperfibrinolysis (percent fibrinolysis after 60 min (LY60)15%) was observed in 3 patients in the ED with a 67% fatality rate (P =0.001 by chi-square testing). PlateletMapping assays correlated with the need for blood transfusion. The abnormal TEG System parameters correlated with fatality. These coagulopathies were already evident OS. The TEG assays can assess coagulopathy, platelet dysfunction, and hyperfibrinolysis at an early stage posttrauma and suggest more effective interventions.

The anticoagulant effect of enoxaparin is readily observed by Thrombelastography (TEG), particularly on the reaction time (R) to form a clot, and is completely reversed by heparinase. In this study, recalcified citrated whole blood with heparinase (CNHR) and without (CNR), along with TEG R time, was used to derive a delta R (CNR-CNHR). This delta R (DeltaR) was then used to measure enoxaparin anticoagulation, which was correlated by linear regression (r(2)=0.806) with plasma anti-Xa in 48 thrombophilic pregnancy patients. In a follow up study whole blood from 15 thrombophilic and 15 normal pregnancy subjects was titrated ex vivo with enoxaparin and TEG DeltaR determined. Linear dose responses (all r(2)>0.9) of DeltaR versus plasma enoxaparin concentration were obtained for each subject. A large variation in slope was observed for both thrombophilic (>7 fold, 217 to 1,588 s DeltaR/unit anti-Xa) and normal (>3 fold, 788 to 2,758) pregnancy subjects. The average slope for the thrombophilic group (710 s DeltaR/unit anti-Xa) was significantly (P=0.002) lower than the normal pregnancy group (1,354 s), indicating resistance to enoxaparin anticoagulation in the thrombophilic group. This technique may help gauge the appropriate dose of enoxaparin for each individual, check for residual anticoagulation before invasive procedures, and perhaps help screen for thrombophilic subjects.

Clinically monitoring recovery from clopidogrel and nonsteroidal anti-inflammatory drug (NSAID) inhibition requires whole blood assays corresponding to a standard methodology such as platelet-rich plasma aggregation monitored optically (OPA). We compared OPA, using an ED 50 dose of adenosine diphosphate activation, with 2 whole blood assays, Plateletworks (PWA) and modified Thrombelastograph (TEG). Two sets of assays were performed on 43 surgery patients while on clopidogrel and off clopidogrel to determine the reversal of absolute and relative inhibition. The modified TEG had Spearman correlations with OPA for absolute (rho = .424; P = .006) and relative inhibition (rho = .742; P < .0001). PWA correlations with OPA gave absolute (rho = .28; P = .08) and relative inhibition (rho = .46; P = .004) values. Bland-Altman analysis indicated agreement of both tests with OPA, showing constant biases of about 18% and some dependency on mean magnitude error. Cohen effect size thresholds defined nonresponders as < 7.7% clopidogrel inhibition relative to baseline recovery of full platelet function. Apparent nonresponse to clopidogrel or lack of platelet recovery did not correlate with statin or NSAID therapies. These PWA and modified TEG whole blood assays could prove useful for monitoring the reversal of clopidogrel and NSAID inhibition before surgery. More important, these assays done at baseline and after beginning clopidogrel therapy could monitor the effectiveness for the individual patients with cardiovascular disease and help identify the need for alternative therapies.

BACKGROUND Aspirin-resistant platelet activation in whole blood is attributable to a transcellular pathway not detected by isolated platelet aggregometry. Aspirin resistance as defined by urinary thromboxane levels is associated with increased risk for myocardial infarction or cardiac death. Whole blood point-of-care assays may also detect aspirin resistance. METHODS We compared PlateletMapping® with VerifyNow® for detecting aspirin resistance in 200 patients undergoing invasive cardiac procedures. This included 10 patients not receiving aspirin therapy for comparison. The assay results were correlated with urinary 11-dehydro-thromboxane B2 collected 2 to 8 hours after the procedure. RESULTS PlateletMapping detected aspirin resistance in 32% of patients. VerifyNow detected aspirin resistance in 6% of patients. A patient's compliance with aspirin therapy was confirmed by a

Platelet function was evaluated before and after clopidogrel therapy in 50 cardiology candidates scheduled for intervention; results were averaged from optical platelet aggregation with 2 significantly correlated point-of-care instruments, Thrombelastograph and Ichor PlateletWorks. Although this was a limited study with few complications, the failure of clopidogrel therapy (30% nonresponders with

Study Objective To validate a Thromboelastograph (Haemoscope Corporation, Niles, IL) assay for functional fibrinogen. Design Correlation study of the Thromboelastograph assay with two conventional fibrinogen assays by the standard Clauss method. Setting Research laboratory of a university medical center. Participants and Interventions Blood samples were obtained from 19 healthy volunteers. Measurement and Main Results Thromboelastograph assays, using heparinized whole blood from 19 healthy donors, indicated that reptilase-XIIIa mixture (Activator f )–generated clot shear elasticity in dynes per square centimeter ( G f ) correlated with fibrinogen (mg/dL). Blood from four donors was used to define the contribution of hematocrit (Hct) to G f by titration with platelet-rich plasma. The G f versus Hct gave linear correlations ( r 2 = 0.746) with G f = 1258 − 17.8 × % Hct. A commercial collection of 19 normal, 10 borderline, and one deficient for functional fibrinogen-citrated plasmas was assayed for G f after recalcification using Activator f . Of the 30 plasma samples, four were from factor X– or factor VII–deficient donors and one was from a coumadin-treated donor. There was a linear correlation of Activator f G f with functional fibrinogen ( r 2 = 0.940) with G f = −730 + 9.21 × fibrinogen (mg/dL). Conclusion Thrombelastography with Activator f may be used to determine fibrinogen levels in whole blood.

The aim of this study was to describe the clinical, functional, and morphologic characteristics of platelets in Cavalier King Charles Spaniel dogs (Cavaliers).Blood from 69 clinically normal Cavaliers was collected and anticoagulated with ethylenediamine-tetraacetic acid (EDTA) and citrate. Automated and manual platelet counts were obtained. Percent platelet aggregation in response to ADP (2, 4, 8, 16, and 32 microM) was determined. Electron microscopy was performed to examine platelet internal morphology and dense granule distribution. A cardiologist recorded the quality of murmurs.Thrombocytopenia (100,000/microL) was present in 51.43% (36/69) of Cavaliers. Macrothrombocytes (3 microm) were present in 33.33% (22/69). Mean manual platelet count was 118,770/microL. Manual (EDTA blood) and automated (EDTA and citrated blood) methods of platelet counting were correlated. Prevalence of cardiac murmurs was 38% (26/69). There was no association between affected dogs and murmur, signalment, or coat color. Mean percent platelet aggregation was significantly higher in controls than in Cavaliers (79% vs 38%, p=0.001). Response to ADP was unaffected by thrombocytopenia, macrothrombocytes, murmur, or any combination thereof. Platelet electron microscopy showed normal and giant sized platelets with normal internal morphology.A benign inherited giant platelet disorder affects approximately 50% of Cavalier King Charles Spaniels. It is characterized by thrombocytopenia, macrothrombocytes, or decreased platelet aggregation in response to ADP. Platelet ultrastructure is normal. Citrated or EDTA blood provides accurate platelet counts. Further studies are indicated to determine platelet glycoprotein structure and any association with mitral endocardiosis. Cavaliers may be useful models of inherited giant platelet disorders.

Platelets play a major role in thrombus formation, as well as in the pathogenesis of atherothrombosis. Inhibition of platelet function is now emphasised more than ever for prevention and treatment of almost all vascular diseases, since thrombosis is established as the key pathogenic event causing acute ischaemic coronary and cerebrovascular syndromes. Although acetylsalicylic acid (aspirin) has been shown to reduce the incidence of myocardial infarction and stroke, its effect is weak and more effective antithrombotic agents are required to manage patients at high-risk for recurrent vascular events. Platelet glycoprotein IIb/IIIa receptor (GPIIb/IIIa) blockade represents a significant advance in interventional cardiology and treatment of acute ischaemic syndromes. The past several years have seen the introduction of many platelet GPIIb/IIIa blockers into the clinical arena targeting the unique platelet GPIIb/IIIa receptor for the adhesive proteins, fibrinogen and von Willebrand Factor. Platelet GPIIb/IIIa blockers administered intravenously have proven efficacious in mitigating arterial thrombosis in acute coronary syndromes (unstable angina and non-ST-elevation myocardial infarction) and percutaneous coronary interventions (PCI) such as balloon dilatation and stent implantation. Currently, orally-active platelet GPIIb/IIIa blockers are being developed to provide additional benefits for primary and secondary prevention of thrombosis as chronic treatment, especially in high-risk patients. Lotrafiban (SmithKline Beecham) is a member of the latest generation of orally-active platelet GPIIb/IIIa blockers undergoing Phase III clinical trials to test the relative effectiveness versus other oral platelet inhibitors for ischaemic conditions including unstable angina, restenosis after PCI and stroke. Lotrafiban is converted from an esterified prodrug by plasma and liver esterases to a peptidomimetic of the arginine-glycine-aspartic acid amino acid sequence. This sequence itself mimics the binding site of fibrinogen and von Willebrand Factor to the platelet GPIIb/IIIa receptor. Preliminary results of the clinical trial APLAUD (antiplatelet useful dose) show that lotrafiban is clinically safe and well-tolerated in patients with recent myocardial infarction, unstable angina, transient ischaemic attack (TIA), or stroke when added to aspirin therapy. With lotrafiban, a worldwide large-scale Phase III clinical trial BRAVO (blockage of the GPIIb/IIIa receptor to avoid vascular occlusion) is currently underway. In general, GPIIb/IIIa blockade seems clinically very promising. A number of unresolved issues, however, remain to be elucidated.