Audrey S. Chang

Measurement of lumbar lordosis. Evaluation of intraobserver, interobserver, and technique variability

Study Design Sixty radiographs were measured on two separate occasions by three physicians using four different techniques to evaluate the reliability and reproducibility of the measurement of lumbar lordosis. Objective To evaluate clinical methods of measuring lumbar lordosis, determining intraobserver and interobserver reliability. Summary of Background Data Several different methods are used to measure lumbar lordosis. The reliability and reproducibility of these has not been well studied. Methods Sixty lateral full spine radiographs were obtained, labeled, and the lumbar lordosis measured independently by three practitioners who routinely perform these measurements. Four measurement techniques were used. These included measurements from the inferior endplate of T12 to the superior endplate of S1; the superior endplate of L1 to the superior endplate of S1; the inferior endplate of T12 to the inferior endplate of L5; and the superior endplate of L1 to the inferior endplate of L5. The measurements then were repeated after relabeling. Results Intraobserver reliability coefficients ranged from 0.83 to 0.92, indicating excellent reproducibility. Ninety‐two percent of repeat measures were within 10°. High overall and pairwise agreement among the three observers also was present; the interobserver reliability coefficients ranged from 0.81 to 0.92. Conclusions The measurement of lumbar lordosis is reproducible and reliable if the technique is specified and one accepts 10° as acceptable variation. Factors that affect the reproducibility of measurement include end vertebra selection (especially with transitional segments) and vertebral endplate architecture.

Measurement of Thoracic and Lumbar Fracture Kyphosis : Evaluation of Intraobserver, Interobserver, and Technique Variability

Study Design. Statistical analysis of various measurement techniques for thoracolumbar burst fracture kyphosis on lateral radiograph. Objective. To determine the most reliable measurement technique. Summary of Background Data. The treatment of thoracic and lumbar burst fractures involves many factors, including the degree of resultant kyphosis. Although various methods have been described, no study has directly compared these methods for reliability and reproducibility. Methods. Fifty lateral radiographs of thoracic and lumbar burst fractures were randomly selected and measured on two separate occasions by three spine surgeons using five different measurement techniques. Radiograph quality, fracture type, and the center beam location were determined. Statistical analysis included analysis of variance for repeated measures and analysis of variance using a generalized linear model. Results. Intraclass correlation coefficients were most consistent for Method 1 (rho = 0.83–0.94) followed by Method 4 (rho = 0.65–0.89) and Method 5 (rho = 0.73–0.85). Intraobserver agreement (% of repeated measures within 5° of the original measurement) ranged between 72% and 98% for all techniques for all three observers, with Method 1 showing the best agreement (84%–98%). Paired comparisons between observers varied considerably with interobserver reliability correlation coefficients ranging from 0.52 to 0.93. Method 1 showed the highest interobserver reliability coefficient (0.81, range 0.71–0.93) followed by Method 5 (0.71, range 0.68–0.75). Method 1 also had the highest percentage of agreement within categories (90% within 5°). Conclusions. Method 1 (measuring from the superior endplate of the vertebral body one level above the injured vertebral body to the inferior endplate of the vertebral body one level below) showed the best intraobserver and interobserver reliability overall.

Risk factors for failure and complications of intradiscal electrothermal therapy: a pilot study.

Study Design. A bi-institutional, retrospective clinical data analysis. Objectives. To determine risk factors for failure and complications of intradiscal electrothermal therapy, a treatment for discogenic back pain. Summary of the Background Data. Intradiscal electrothermal therapy is a relatively new treatment for discogenic back pain. Though previous studies have shown it to be an effective treatment, there are few published studies examining complications and none examining risk factors for failure. Methods. The authors treated 79 patients with discogenic back pain using intradiscal electrothermal therapy. Complications were assessed by patient report and, when indicated, further diagnostic testing. Success or failure was determined by visual analogue pain scores at 6-month follow-up. Variables examined for their relationship to failure and complications were age, sex, duration of pain, number of levels heated, smoking history, diabetes, obesity, leg pain, and previous back surgery. Results. Forty-eight percent of patients reported more than 50% pain relief at their 6-month follow-up. There were eight complications (10%), most of which were self-limited and transient. The only risk factor associated with intradiscal electrothermal therapy failure was obesity (P = 0.01). Whereas 54% of nonobese patients reported good pain relief at 6 months, only one out of 10 obese patients had successful intradiscal electrothermal therapy. The obese patients in our study were more likely to have a complication from intradiscal electrothermal therapy than they were to obtain pain relief. Conclusion. The only risk factor found to be associated with IDET outcome was obesity, which was a strong predictor of failure. Obesity should be considered a relative contraindication to performing IDET.

Epidural Steroids, Etanercept, or Saline in Subacute Sciatica: A Multicenter, Randomized Trial

BACKGROUND Active surveillance (AS) and watchful waiting (WW) have been proposed as management strategies for low-risk, localized prostate cancer. PURPOSE To systematically review strategies for observational management of prostate cancer (AS or WW), factors affecting their utilization, and comparative effectiveness of observational management versus immediate treatment with curative intent. DATA SOURCES MEDLINE and Cochrane databases (from inception to August 2011). STUDY SELECTION Screened abstracts and reviewed full-text publications to identify eligible studies. DATA EXTRACTION One reviewer extracted data, and another verified quantitative data. Two independent reviewers rated study quality and strength of evidence for comparative effectiveness. DATA SYNTHESIS Sixteen independent cohorts defined AS, 42 studies evaluated factors that affect the use of observational strategies, and 2 evidence reports and 22 recent studies reported comparisons of WW versus treatment with curative intent. The most common eligibility criteria for AS were tumor stage (all cohorts), Gleason score (12 cohorts), prostate-specific antigen (PSA) concentration (10 cohorts), and number of biopsy cores positive for cancer (8 cohorts). For monitoring, studies used combinations of periodic PSA testing (all cohorts), digital rectal examination (14 cohorts), and rebiopsy (14 cohorts). Predictors of receiving no active treatment included older age, comorbid conditions, lower Gleason score, tumor stage, PSA concentration, and favorable risk group. No published studies compared AS with immediate treatment with curative intent. Watchful waiting was generally less effective than treatment with curative intent; however, applicability to contemporary patients may be limited. LIMITATIONS Active surveillance and WW often could not be differentiated in the reviewed studies. Published randomized trials have assessed only WW and did not enroll patients diagnosed by PSA screening. CONCLUSION Evidence is insufficient to assess whether AS is an appropriate option for men with localized prostate cancer. A standard definition of AS that clearly distinguishes it from WW is needed to clarify scientific discourse. PRIMARY FUNDING SOURCE Agency for Healthcare Research and Quality.

Reductions in platelet force development by cardiopulmonary bypass are associated with hemorrhage

Quantitative assessment of platelet dysfunction after cardiopulmonary bypass (CPB) and prediction of excessive microvascular bleeding remain elusive goals.We used a sensitive instrument capable of simultaneously measuring the force generated by platelets during plasma clot retraction and global clot strength. We hypothesized that CPB would significantly reduce these two variables. Platelet-rich plasma was obtained from eight patients undergoing aortocoronary revascularization prior to induction, after 90 min of CPB, and after protamine administration. Platelet force development was measured using a standardized technique that controlled for platelet number and permitted clot formation in the presence of heparin. Despite the presence of a measurable elastic modulus, platelet force development during bypass was abolished. Peak platelet force development after CPB was significantly lower than before CPB (5255 +/- 955 dynes vs 11,600 +/- 780 dynes, P = 0.01). The percent recovery (after/before bypass) of peak platelet force development inversely correlated with tube thoracostomy drainage during the first 24 h after placement (rs = -0.71, P = 0.048). This study demonstrates that CPB has dramatic effects on platelet force development. The correlation between the percent recovery of peak platelet force development and blood loss supports the clinical relevance of this measurement. (Anesth Analg 1995;80:459-65)

A modified thromboelastographic method for monitoring c7E3 Fab in heparinized patients.

The monoclonal antibody, c7E3 Fab, binds to the platelet surface fibrinogen receptor (GPIIb/IIIa), inhibiting platelet aggregation and clot retraction.We performed an in vitro study to assess the ability of a modification of the thromboelastograph (MTEG) to detect inhibition of clot strength by c7E3 Fab and its reversal with platelet-rich plasma (PRP). In the modified assay (MTEG), thrombin was added to whole blood (WB) and platelet-poor plasma (PPP) and the resultant maximum amplitude (MA) was measured, MAWB and MAPPP, respectively. Anticoagulated blood samples from 17 patients scheduled for cardiac surgery were collected for a dose response (Part I; n = 5) and c7E3 Fab reversal (Part II; n = 12) study. Clot strength was reduced in a dose-dependent manner by c7E3 Fab. Ecteola cellulose effectively reversed the effect of heparin on the thrombin time and the addition of PRP significantly increased the MAWB (P < 0.0001) and MAWB-ppp (P < 0.0001). Subtracting the MAPPP from MAWB significantly magnified the response of MA to the addition of c7E3 Fab (P = 0.002) and its reversal with PRP (P = 0.005). This in vitro study indicates that the MTEG is a responsive assay demonstrating that inhibition by the antiplatelet c7E3 Fab is reversible with PRP. (Anesth Analg 1997;84:31-8)

Probing for thoracic pedicle screw tract violation(s): Is it valid?

Background: Preparation of the thoracic pedicle screw tract is a critical step prior to the placement of screws. The ability to detect pedicle wall violation(s) by probing prior to insertion of thoracic pedicles screws, however, has not been studied. The purpose of this study was to evaluate the inter- and intraobserver agreement and the accuracy in detecting thoracic pedicle screw tract violation(s) among surgeons at various levels of training. Methods: With use of a straightforward trajectory, under direct visualization, 108 thoracic pedicle screw tracts (54 cadaveric thoracic vertebrae) were prepared in a standard fashion, followed by tapping with a 4.5-mm cannulated tap. A deliberate pedicle violation was randomly created by an independent investigator in either the anterior, the medial, or the lateral wall in 65 pedicles. Following this, four blinded, independent surgeons at various levels of training probed the specimens on three separate occasions to determine if a breach was present (1296 discrete data points). Surgeon findings were then recorded as breach present or absent and, if present, breach location. The Cohen κ correlation coefficient (κa) and 95% confidence interval were used to assess the accuracy of the observers and the inter- and intraobserver agreement. Results: The mean accuracy over three iterations, the validity in detecting the breach location, and the intraobserver agreement varied by level of training and experience, with the most experienced observer (observer 1) scoring the best and the least experienced observer (observer 4) scoring the worst. The three most senior surgeons had good intraobserver agreement. Interobserver agreement was low between the four observers. Conclusions: An observer’s ability to accurately detect the presence or absence of a pedicle tract violation and the breach location, if present, is dependent on the surgeon’s level of training. Probing the pedicle tract prior to placement of pedicle screws in the thoracic spine is likely a learned skill that improves with repetition and experience.

The intravenous ketamine test: A predictive response tool for oral dextromethorphan treatment in neuropathic pain

IV infusion tests performed to predict subsequent response to oral analgesics are an increasingly popular method used to enhance medical care and conserve resources. Because no infusion test is completely accurate, the potential benefits of these tests must be weighed against the frustration and waste in resources encountered with false-positive results, and the failure to use a potentially beneficial treatment with false-negative results. In recent years, drugs that act antagonistically at N-methyl-d-aspartate receptors have been shown to be valuable adjuncts in the treatment of pain. To determine the predictive value of small-dose (0.1 mg/kg) IV ketamine on an oral dextromethorphan (DX) treatment regimen, we analyzed the analgesic response to these drugs in 25 patients at 2 tertiary care military treatment facilities, institutions at which DX is not readily accessible. When ≥50% response for both drugs was used as the outcome measure for success, the positive predictive value of the ketamine test was 64%, the negative predictive value 73%, and the observed agreement 68%. However, when ≥67% relief with ketamine was used as an outcome measure (as determined by a receiver operating characteristic curve), the positive predictive value was 90%, the negative predictive value 80%, and the observed agreement increased to 84%. Based on these results, we conclude that an IV ketamine test may be useful in predicting response to oral DX. More research is needed to determine the ideal candidates for such a test, and the optimal dose and cutoff value for the response to ketamine.

Near-site monitoring of the antiplatelet drug abciximab using the hemodyne analyzer and modified thrombelastograph

OBJECTIVE This investigation examines the hypothesis that the antiplatelet effect of abciximab and its reversal can be monitored using the Hemodyne (Hemodyne, Inc, Midlothian, VA) analyzer and modified Thrombelastograph (Haemoscope, Skokie, IL). DESIGN In vitro dose-response and reversal study. SETTING Anesthesia Research (Dallas, TX) and Special Studies Coagulation Laboratories (Washington, DC). PARTICIPANTS Nine healthy volunteers. INTERVENTIONS The addition of increasing concentrations of abciximab, 0 to 10 microg/mL, and purified fibrinogen, 50 to 400 mg/dL. The reversal of abciximab, 4 microg/mL, with the addition of fresh platelet-rich plasma (PRP) sufficient to increase the platelet concentration by approximately 10%. MEASUREMENTS AND MAIN RESULTS Platelet aggregation and platelet contractile force using the Hemodyne analyzer were used as platelet-specific measurements. The Thrombelastograph maximum amplitude (MA) for platelets (MA(PLT)) was calculated by subtracting the MA from a platelet-poor plasma (PPP) sample (MA(ppp)) determined in one thromboelastography well from that of whole-blood MA (MA(WB)) run simultaneously in the second thromboelastography well. The addition of abciximab, 0 to 10 microg/mL, resulted in significant concentration-dependent reductions in platelet aggregation (p < 0.001), platelet contractile force (p < 0.001), and MA(PLT) (p < 0.001). Platelet contractile force (p < 0.03) and MA(PLT) (p < 0.05) were significantly more responsive than MA(WB) to the effect of abciximab, 4 microg/mL, and its reversal with the addition of fresh PRP. Purified fibrinogen concentration directly correlated with thromboelastography MA (r(s) = 0.97; p < 0.001), yet had no effect on platelet contractile force. The addition of abciximab had no measurable influence on the MA(ppp). CONCLUSION This in vitro study suggests that the Hemodyne analyzer and modified Thrombelastograph might be clinically useful methods to monitor the platelet inhibitory effects of agents such as abciximab.

The incidence of heparin-induced antibodies in patients undergoing vascular surgery: A prospective study

PURPOSE This study prospectively assessed the incidence of heparin-induced antibodies in patients undergoing peripheral vascular surgery and determined whether the incidence is influenced by previous heparin exposure. METHODS Fifty-four hospitalized patients (36 men and 18 women) undergoing peripheral vascular surgery and receiving intraoperative heparin anticoagulation were studied. Unfractionated porcine heparin was given for intraoperative anticoagulation and was not continued postoperatively. Carotid endarterectomy was performed in 36 patients, aortic reconstruction in 11 patients, and infrainguinal bypass in 7 patients. Plasma was tested before and after (14 +/- 7.5 [SD] days) surgery for IgG antibodies to the complex of heparin/platelet factor 4, using a standardized, validated enzyme-linked immunosorbent assay (ELISA). Results are expressed as an optical density ratio (ODR) of patient plasma to normal plasma, with the threshold for a positive result of > or = 1.8. Platelet counts and clinical outcomes were also assessed. RESULTS The mean patient age was 67.2 +/- 9.7 years. A prior exposure to heparin was documented in 41% of patients. The mean intraoperative heparin dose was 9089 +/- 3607 units. Only 1 patient converted from a negative antibody status to a positive status (1.9%, 95% CI = 0.10%-11.18%). The change in the ELISA ODR after surgery was not significantly different for patients with (+0.042 +/- 0.272) and without (-0.022 +/- 0.299, P = 0.57) prior heparin exposure. Postoperatively, the platelet counts dropped from 227,620 +/- 78,308 microL, to 185,706 +/- 80,842 microL (P < .001). The decrease in platelet count was the same in patients with prior heparin exposure (-23.0 +/- 18.0%) and without (-18.0 +/- 14.0%, P = .46). One thrombotic complication occurred, a femorotibial bypass graft occlusion in a patient who tested negative for antibodies. CONCLUSION Heparin-induced antibodies occur infrequently after peripheral vascular surgery. The commonly observed, mild degree of postoperative thrombocytopenia does not appear to be caused by heparin-induced antibodies. These results indicate that a standard dose of heparin for intraoperative anticoagulation during vascular surgery is not associated with a significant risk of heparin-induced thrombocytopenia and thrombosis.