Nurse-run preanaesthesia assessment clinics: an initiative towards improving the quality of perioperative care at the ambulatory care centre.

INTRODUCTION: Nurse-run preanaesthesia assessment is well established in ambulatory surgery. However, in the Middle East the implementation of such a service is new and needed careful preparation. Aim of this audit is to assess the feasibility and the quality of preoperative assessments by the specially trained nurses, patient and nurse satisfaction and overall perioperative quality of recovery. METHODS: The nurses were selected and trained first in an accredited programme. Then an implementation period of 3 month was used for them to gain experience. Hereafter, we performed a four-step audit on the quality of preassessment, the patient's satisfaction, the quality of recovery and adverse events if any. Finally, we also monitored the nurse's satisfaction of their new advanced role. RESULTS: The quality of preanaesthesia assessment was high as with 95% compliance to the accepted standards. In the patient satisfaction survey, all 152 patients were either highly satisfied or satisfied with the nurse-run service. The nurses were also highly satisfied and felt that they were either highly or moderately valued. All the patients who were operated at the ambulatory care services were followed up postoperatively by telephone calls which revealed that most of them were highly satisfied. No major or minor adverse events occurred. CONCLUSION: Our specially trained nurses perform preoperative assessments on high standard without adverse events, while patient and staff satisfaction is very high. Future projects will focus on reducing the rate of cancellation of surgeries, investigating the cost-effectiveness of this approach as well as training the specialised nurses for paediatric preoperative anaesthesia assessments. This model of care could induce further nurse-run models of care in the Middle East.

A 3rd ventricular colloid cyst causing acute hydrocephalus with stunned myocardium: A case report.

BACKGROUND: Third ventricular colloid cysts are benign but may cause acute hydrocephalus, raised intracranial pressure, decreased consciousness level, and sudden death. These ventricular colloid cysts associated with stunned myocardium are rarely reported in the literature. This study reported a case of a third ventricular colloid cyst presented as acute hydrocephalus complicated with severe neurogenic pulmonary edema, stunned myocardium, and heart failure, which survived at the end. CASE PRESENTATION: A 29-year-old woman presented to the emergency department with one day history of headache, vomiting, and altered consciousness level. Early brain imaging showed a cyst in the third ventricle. The patient rapidly deteriorated neurologically and developed severe pulmonary edema and heart failure requiring immediate external ventricular drain and heart failure management. Once stabilized, she underwent endoscopic excision of the ventricular cyst. Histopathology confirmed the diagnosis of colloidal cyst. She survived all these acute life-threatening events, improved, and stabilized, and was discharged home. She was followed up in outpatient clinics after 6 months of discharge with no symptoms or neurological deficit. CONCLUSION: A third ventricular colloid cyst can cause acute hydrocephalus leading to stunned myocardium requiring immediate surgical intervention, advanced hemodynamic monitoring, and acute heart failure management.

Validity and time course of surgical fear as measured with the Surgical Fear Questionnaire in patients undergoing cataract surgery.

OBJECTIVES: The primary aim of the study was to assess the convergent validity of the Surgical Fear Questionnaire (SFQ) with other self-report instruments and biological indices of stress. Secondary aims were the examination of predictors of the level and time course of fear and preferences for fear treatment. METHODS: In a prospective observational cohort study SFQ short-term (SFQ-s) and long-term (SFQ-l) scores were assessed one week, one day, and the morning before cataract surgery, together with salivary cortisol and alpha-amylase (sAA) levels, and numeric rating scale (NRS) fear score. SFQ-scores were also assessed before second eye surgery. Expected pain and recovery, and sociodemographic and medico-psychological predictors of fear were assessed at baseline. RESULTS: Data of 98 patients were analyzed. Scores of both SFQ-subscales (range 0-40) were generally low, all mean ≤ 9.0. SFQ-s and SFQ-l correlated significantly with the other self-report instruments: NRS fear .83 and .89, expected pain .49 and .54, expected recovery -.27 and -.44. No association was found between SFQ-scores and cortisol or sAA level. Predictors of the level of fear were baseline pain and stress. Additional effects of time were found for subgroups based on educational level, antidepressant use, and presurgical stress (SFQ-l). SFQ-scores were significantly lower before the second cataract surgery than before the first, and higher in patients who would have appreciated treatment of fear. DISCUSSION: Convergent validity of the SFQ with other self-report measures is shown. The sensitivity of the SFQ permits the detection of small variations in fear caused by time or other factors.

Prevalence and Predictors of Patient Nonadherence to Pharmacological Acute Pain Therapy at Home After Day Surgery: A Prospective Cohort Study.

BACKGROUND: Good adherence to prescribed analgesics can be crucial to suppress or even prevent acute postoperative pain after day surgery. The aim of this study was to analyze prevalence and predictors of analgesic nonadherence after day surgery. METHODS: Elective patients scheduled for day surgery were prospectively enrolled from November 2008 to April 2010. Outcome parameters were measured by using questionnaire packages at 2 time points: 1 week preoperatively and 4 days postoperatively. The primary outcome parameter was analgesic nonadherence. Adherence was defined according to the patient's response to the questionnaire item "analgesia use as prescribed": full adherence, "yes"; partial adherence, "yes, sometimes"; nonadherence, "no." Bivariate and multivariate logistic regression analyses were performed to identify predictors of analgesic nonadherence. RESULTS: A total of 1,248 patients were included. The prevalence rates of analgesic nonadherence and partial adherence were 21.6% and 20.0%, respectively, in the total study population but dropped to 9.4% and 19.8%, respectively, in patients with moderate to severe pain. Low postoperative pain intensity and short duration of surgery were the most important predictors of analgesic nonadherence. The most important preoperative predictors for analgesic nonadherence were low preoperative pain intensity, low preoperative expectations of pain, and low fear of short-term effects of surgery. CONCLUSION: Analgesic nonadherence and partial adherence are common after day surgery but decrease as average pain intensity increases. Patients at risk for analgesic nonadherence can be identified during the preoperative period based on preoperative pain intensity, preoperative expectations of pain, and fear of surgery.

Prevalence and predictors of depression and well-being after hysterectomy: An observational study.

OBJECTIVES: To assess risk and predictive factors for depression and well-being, 3 and 12 months after elective hysterectomy. Secondary objectives were to assess the incidence of depression, level of well-being, and feelings of femininity. STUDY DESIGN: A prospective multicenter cohort study was performed among 419 women, undergoing hysterectomy for benign indication. Data were collected in the week prior to surgery, and in the per- and postoperative period up to the fourth postoperative day and 3 and 12 months after surgery. Sociodemographic variables, baseline health status, psychosocial predictors, and surgery data were assessed. Outcome measures were Center for Epidemiological Studies-Depression scale (CES-D, range 0-60), the 12-item well-being questionnaire energy and positive well-being subscales (range 0-12), and feelings of femininity. Predictor analyses were performed using linear mixed model analyses. RESULTS: Levels of depression, energy, and positive well-being after hysterectomy were predicted by their corresponding baseline levels (estimate 0.62 p<0.001, 0.39 p<0.001, 0.37 p<0.001, respectively) and baseline pain (0.31 p=0.003, -0.09 p=0.026, -0.10 p=0.008). Postoperative infection reported at 12 months affected CES-D and energy level. Several other gynaecological, psychosocial, or perioperative factors were also predictive for one of the outcomes. Prevalence of depression at baseline, 3 and 12 months was 24%, 19%, and 21%, respectively. In general, well-being scores were slightly higher 3 and 12 months after hysterectomy than at baseline. Feelings of femininity were not negatively affected in 92% of the patients. CONCLUSIONS: Preoperative psychosocial status, perioperative pain, and postoperative infection were found as predictors of psychological outcome after hysterectomy. In the majority of patients we observed small but significant improvements with regard to postoperative depression and well-being, while feelings of femininity were unaffected.

External Validation and Modification of a Predictive Model for Acute Postsurgical Pain at Home After Day Surgery.

OBJECTIVES: In 2009, Gramke and colleagues have described predictive factors to preoperatively detect those at risk for moderate to severe acute postsurgical pain (APSP) after day surgery. The aim of the present study is to externally validate this initial model and to improve and internally validate a modified version of this model. MATERIALS AND METHODS: Elective patients scheduled for day surgery were prospectively enrolled from November 2008 to April 2010. Model discrimination was quantified using the area under the receiver operating characteristic curve (AUC). Model calibration was assessed by visual inspection of the calibration plot. Subsequently, we modified (different assignment of type of surgery, different cutoff for moderate to severe APSP, continuous of dichotomized variables and testing of additional variables) and internally validated this model by standard bootstrapping techniques. RESULTS: A total of 1118 patients were included. The AUC for the original model was 0.81 in the derivation data set and 0.72 in our validation data set. The model showed poorly calibrated risk predictions. The AUC of the modified model was 0.82 (optimism-corrected AUC=0.78). This modified model showed good calibration. CONCLUSIONS: The original prediction model of Gramke and colleagues performed insufficiently on our cohort of outpatients with respect to discrimination and calibration. Internal validation of a modified model shows promising results. In this model, preoperative pain, patient derived expected pain, and different types of surgery are the strongest predictors of moderate to severe APSP after day surgery.

Correction: Validation of the Surgical Fear Questionnaire in Adult Patients Waiting for Elective Surgery.

[This corrects the article DOI: 10.1371/journal.pone.0100225.].

Recovery 3 and 12 months after hysterectomy: epidemiology and predictors of chronic pain, physical functioning, and global surgical recovery.

Chronic postsurgical pain (CPSP) is 1 important aspect of surgical recovery. To improve perioperative care and postoperative recovery knowledge on predictors of impaired recovery is essential. The aim of this study is to assess predictors and epidemiological data of CPSP, physical functioning (SF-36PF, 0-100), and global surgical recovery (global surgical recovery index, 0-100%) 3 and 12 months after hysterectomy for benign indication.A prospective multicenter cohort study was performed. Sociodemographic, somatic, and psychosocial data were assessed in the week before surgery, postoperatively up to day 4, and at 3- and 12-month follow-up. Generalized linear model (CPSP) and linear-mixed model analyses (SF-36PF and global surgical recovery index) were used. Baseline data of 468 patients were collected, 412 (88%) patients provided data for 3-month evaluation and 376 (80%) patients for 12-month evaluation.After 3 and 12 months, prevalence of CPSP (numeric rating scale ≥ 4, scale 0-10) was 10.2% and 9.0%, respectively, SF-36PF means (SD) were 83.5 (20.0) and 85.9 (20.2), global surgical recovery index 88.1% (15.6) and 93.3% (13.4). Neuropathic pain was reported by 20 (5.0%) patients at 3 months and 14 (3.9%) patients at 12 months. Preoperative pain, surgery-related worries, acute postsurgical pain on day 4, and surgery-related infection were significant predictors of CPSP. Baseline level, participating center, general psychological robustness, indication, acute postsurgical pain, and surgery-related infection were significant predictors of SF-36PF. Predictors of global surgical recovery were baseline expectations, surgery-related worries, American Society of Anesthesiologists classification, type of anesthesia, acute postsurgical pain, and surgery-related infection.Several predictors were identified for CPSP, physical functioning, and global surgical recovery. Some of the identified factors are modifiable and optimization of patients' preoperative pain status and psychological condition as well as reduction of acute postsurgical pain and surgery-related infection may lead to improvement of outcome.

Ruptured spinal arteriovenous malformation: Presenting as stunned myocardium and neurogenic shock.

BACKGROUND: Neurogenic pulmonary edema (NPE) is a clinical syndrome usually defined as an acute pulmonary edema occurring shortly after a central neurologic insult. NPE was identified 100 years ago, but it is still underappreciated in the clinical setup. NPE usually appears within minutes to hours after the injury. It has a high mortality rate if not recognized early and treated appropriately. Similarly, neurogenic shock is a known complication of spinal cord injury reported incidence is more than 20% in isolated upper cervical spinal injury. But NPE is rare to occur, and stunned myocardium (SM) is not reported in spinal arteriovenous malformation (AVM) rupture. SM is a reversible cardiomyopathy resulting in transient left ventricular dysfunction which has been described to occur in the setting of catecholamine release during situations of physiologic stress. We report a case of high spinal AVM rupture presenting as SM, NPE, and neurogenic shock. CASE DESCRIPTION: A 32-year-old male who presented with sudden onset of pain and weakness in upper limbs. Imaging studies showed AVM rupture by imaging techniques. Initially, the patient had severe hypertension, respiratory distress requiring intubation and ventilation, then he developed hypotension, bradycardia, and asystole, which required immediate cardiopulmonary resuscitation and atropine. He remained with quadriplegia and suffered from frequent episodes of bradycardia and asystole. CONCLUSIONS: Spinal AVM rupture can present as neurogenic shock, stunned myocardium, and pulmonary edema. Early recognition of AVM rupture and prompt surgical intervention, as well as aggressive treatment of shock, may enhance recovery and decrease the long-term morbidity.

Prevalence and Predictive Factors of Chronic Postsurgical Pain and Global Surgical Recovery 1 Year After Outpatient Knee Arthroscopy: A Prospective Cohort Study.

Outpatient knee arthroscopy is one of the most commonly performed surgical procedures. Previous research has demonstrated that chronic postsurgical pain (CPSP) after outpatient surgery is prevalent. Our objective was to determine the prevalence and predictive factors of CPSP and Global Surgical Recovery (GSR) 1 year after knee arthroscopy.A prospective longitudinal cohort study was performed. Patients were included during an 18-month period. Data were collected by using 3 questionnaires: at 1 week preoperatively, 4 days postoperatively, and 1 year postoperatively. A value of >3 on an 11-point numeric rating scale (NRS) was defined as moderate to severe pain. A score of ≤80% on the Global Surgical Recovery Index was defined as poor GSR. Stepwise logistic regression analysis was performed to determine which variables were predictors for CPSP and poor GSR.The prevalence of moderate to severe preoperative pain in patients undergoing knee arthroscopy (n = 104) was 71.2%, of acute postsurgical pain 37.5%, and of CPSP 32.7%. Risk factors for CPSP were the presence of preoperative pain and preoperative analgesic use, with odds ratios of 6.31 (1.25-31.74) and 4.36 (1.58-12.07), respectively. The prevalence of poor GSR 1 year after outpatient knee arthrosocpy was 50.0%. Poor GSR 4 days after the surgery was a risk factor with an odds ratio of 8.38 (0.92-76.58) and quality of life 4 days after surgery was a protective factor with and odds ratio of 0.10 (0.02-0.64).Both CPSP and poor GSR are common 1 year after knee arthroscopy. Patients at risk for CPSP can be identified during the preoperative phase. Prediction of poor GSR 1 year after surgery is mainly related to early postoperative recovery.

Prevalence and Predictive Factors of Chronic Postsurgical Pain and Poor Global Recovery 1 Year After Outpatient Surgery.

OBJECTIVES: To prospectively describe the prevalence and predictive factors of chronic postsurgical pain (CPSP) and poor global recovery in a large outpatient population at a university hospital, 1 year after outpatient surgery. MATERIALS AND METHODS: A prospective longitudinal cohort study was performed. During 18 months, patients presenting for preoperative assessment were invited to participate. Outcome parameters were measured by using questionnaires at 3 timepoints: 1 week preoperatively, 4 days postoperatively, and 1 year postoperatively. A value of >3 on an 11-point numeric rating scale was considered to indicate moderate to severe pain. A score of ≤80% on the Global Surgical Recovery Index was defined as poor global recovery. RESULTS: A total of 908 patients were included. The prevalence of moderate to severe preoperative pain was 37.7%, acute postsurgical pain 26.7%, and CPSP 15.3%. Risk factors for the development of CPSP were surgical specialty, preoperative pain, preoperative analgesic use, acute postoperative pain, surgical fear, lack of optimism, and poor preoperative quality of life. The prevalence of poor global recovery was 22.3%. Risk factors for poor global recovery were recurrent surgery because of the same pathology, preoperative pain, preoperative analgesic use, surgical fear, lack of optimism, poor preoperative and acute postoperative quality of life, and follow-up surgery during the first postoperative year. DISCUSSION: Moderate to severe CPSP after outpatient surgery is common, and should not be underestimated. Patients at risk for developing CPSP can be identified during the preoperative phase.

Controlled-release oxycodone versus naproxen at home after ambulatory surgery: a randomized controlled trial.

BACKGROUND: Strong opioids in the home setting after ambulatory surgery have rarely been studied for fear of hazardous adverse effects such as respiratory depression. OBJECTIVES: We compared the efficacy of paracetamol/controlled-release (CR) oxycodone and paracetamol/naproxen for treatment of acute postoperative pain at home after ambulatory surgery. Secondary outcomes were adverse effects of study medication, treatment satisfaction, and postoperative analgesic compliance. METHODS: Patients undergoing ambulatory knee arthroscopy or inguinal hernia repair surgery (n = 105) were randomized into 3 groups: Group1 paracetamol/naproxen (n = 35), Group 2 paracetamol/CR oxycodone for 24 hours (n = 35), and Group 3 paracetamol/CR oxycodone for 48 hours (n = 35). Pain intensity at movement and at rest using a visual analog scale as well as satisfaction with postoperative analgesia and side effects were recorded for up to 48 hours postoperatively. Compliance with study medication was also assessed. RESULTS: For pain at movement and at rest, no significant differences were found between the paracetamol/naproxen group and either the paracetamol/CR oxycodone for 24 hours group (ß = 2.6 [4.9]; P = 0.597) or the paracetamol/CR oxycodone for 48 hours (ß = -1.7 [5.1]; P = 0.736). No major adverse effects of study medication were registered and satisfaction with postoperative pain treatment was high in all groups. Compliance was comparable across the groups. Despite clear instructions, 8 patients with the lowest pain scores did not use any of the prescribed pain medication. CONCLUSIONS: Paracetamol/CR oxycodone and paracetamol/naproxen are equally effective in treatment of acute postoperative pain at home after ambulatory surgery with comparable patient satisfaction level. We suggest paracetamol/CR oxycodone to be a valuable alternative for the current paracetamol/naproxen gold standard, particularly in patients with a contraindication for nonsteroidal anti-inflammatory drugs. ClinicalTrials.gov identifier: NCT02152592.

Continuous paravertebral block for postoperative pain compared to general anaesthesia and wound infiltration for major oncological breast surgery.

We hypothesized that improved acute postoperative pain relief will be achieved using general anaesthesia (GA) either in combination with continuous thoracic paravertebral block (GA-cPVB) or single shot (GA-sPVB) as compared to GA supplemented by local wound infiltration (GA-LWI) after unilateral major breast cancer surgery. A randomised controlled trial was conducted in 46 adult women in a day-care or short-stay hospital setting after major breast cancer surgery. Pain-intensity was measured using an 11-point visual analogue scale (VAS) until postoperative day 2. GA-sPVB was stopped due to slow inclusion. No significant difference in VAS score was noted between GA-LWI (VAS median 0.5 (interquartile range 0.18-2.00)) and GA-cPVB, (VAS 0.3 (0.00-1.55, p = 0.195)) 24 hours after surgery or at any point postoperatively until postoperative day 2. We conclude that both GA-LWI and GA-cPVB anaesthetic techniques are equally effective in treatment of acute postoperative pain after major oncological breast surgery. As GA-LWI is easily to perform with fewer complications and it is more cost-effective it should be preferred over GA-cPVB.

Validation of the surgical fear questionnaire in adult patients waiting for elective surgery.

OBJECTIVES: Because existing instruments for assessing surgical fear seem either too general or too limited, the Surgical Fear Questionnaire (SFQ) was developed. The aim of this study is to assess the validity and reliability of the SFQ. METHODS: Based on existing literature and expert consultation the ten-item SFQ was composed. Data on the SFQ were obtained from 5 prospective studies (N = 3233) in inpatient or day surgery patients. These data were used for exploratory factor analysis (EFA), confirmatory factor analysis (CFA), reliability analysis and validity analysis. RESULTS: EFA in Study 1 and 2 revealed a two-factor structure with one factor associated with fear of the short-term consequences of surgery (SFQ-s, item 1-4) and the other factor with fear of the long-term consequences of surgery (SFQ-l, item 5-10). However, in both studies two items of the SFQ-l had low factor loadings. Therefore in Study 3 and 4 the 2-factor structure was tested and confirmed by CFA in an eight-item version of the SFQ. Across all studies significant correlations of the SFQ with pain catastrophizing, state anxiety, and preoperative pain intensity indicated good convergent validity. Internal consistency (Cronbach's alpha) was between 0.765-0.920 (SFQ-total), 0.766-0.877 (SFQ-s), and 0.628-0.899 (SFQ-l). The SFQ proved to be sensitive to detect differences based on age, sex, education level, employment status and preoperative pain intensity. DISCUSSION: The SFQ is a valid and reliable eight-item index of surgical fear consisting of two subscales: fear of the short-term consequences of surgery and fear of the long-term consequences.

Reduced incidence of chronic postsurgical pain after epidural analgesia for abdominal surgery.

BACKGROUND: Chronic postsurgical pain (CPSP) is a common complication of surgery with high impact on quality of life. Peripheral and central sensitization caused by enhanced and prolonged afferent nociceptive input are considered important mechanisms for the development of CPSP. This case-control study investigated whether epidural analgesia is associated with a reduced incidence of CPSP after open abdominal surgery. METHODS: Six months after surgery, Short-Form-36 Health Survey (SF-36) pain scores, possible predictors of chronic pain, and quality of life were assessed. Patients treated with epidural analgesia in combination with general anesthesia (epidural group, N = 51) were compared to patients undergoing matched surgical procedures receiving general anesthesia alone (GA-group, N = 50). Multivariate analysis was performed by logistic regression analysis. RESULTS: Twenty-six (25.7%) patients experienced chronic pain, 9 in the epidural group (17.6%), 17 in the GA-group (34%), crude odds ratio (OR) 0.42 (95% confidence interval (CI) 0.16 to 1.05). After adjustment for the most prominent predictors of CPSP, such as age, sex, pre-operative pain, and acute postoperative pain, the OR for chronic pain in the epidural group was 0.19 (95% CI 0.05 to 0.76). Patients with CPSP reported a significantly lower quality of life compared to patients without CPSP (SF-36 total score median (IQR) 39.2 (27.2 to 56.7) vs. 84.3 (69.9 to 92.5, P < 0.001) and a lower level of long-term global perceived recovery (70.0% (50.0 to 80.0) vs. 90.0% (80.0 to 100.0), P < 0.001). CONCLUSION: Chronic postsurgical pain occurs in a significant number of patients 6 months after open abdominal surgery. Postoperative epidural analgesia is associated with a reduced incidence of CPSP after abdominal surgery.

Introducing the event related fixed interval area (ERFIA) multilevel technique: a method to analyze the complete epoch of event-related potentials at single trial level.

In analyzing time-locked event-related potentials (ERPs), many studies have focused on specific peaks and their differences between experimental conditions. In theory, each latency point after a stimulus contains potentially meaningful information, regardless of whether it is peak-related. Based on this assumption, we introduce a new concept which allows for flexible investigation of the whole epoch and does not primarily focus on peaks and their corresponding latencies. For each trial, the entire epoch is partitioned into event-related fixed-interval areas under the curve (ERFIAs). These ERFIAs, obtained at single trial level, act as dependent variables in a multilevel random regression analysis. The ERFIA multilevel method was tested in an existing ERP dataset of 85 healthy subjects, who underwent a rating paradigm of 150 painful and non-painful somatosensory electrical stimuli. We modeled the variability of each consecutive ERFIA with a set of predictor variables among which were stimulus intensity and stimulus number. Furthermore, we corrected for latency variations of the P2 (260 ms). With respect to known relationships between stimulus intensity, habituation, and pain-related somatosensory ERP, the ERFIA method generated highly comparable results to those of commonly used methods. Notably, effects on stimulus intensity and habituation were also observed in non-peak-related latency ranges. Further, cortical processing of actual stimulus intensity depended on the intensity of the previous stimulus, which may reflect pain-memory processing. In conclusion, the ERFIA multilevel method is a promising tool that can be used to study event-related cortical processing.

Do blood collection methods influence whole-blood platelet function analysis?

Pre-analytical variables interact with standard coagulation parameters. How these variables affect the platelet function analysis is not completely known. How collection site and puncture method affect multiple electrode aggregometry (MEA) and platelet function analyzer (PFA-100®) was compared regarding contact activation. First, volunteers scheduled for elective cardiac surgery had blood collected from four lines: venous, arterial, central venous and by venipuncture. MEA and PFA-100® were analysed blinded for site origin. Second, two samples (citrate, Corn Trypsin Inhibitor, CTI) were collected in syringe or vacuum tubes. Thrombin generation (TG) was determined. MEA was triggered by adenosine diphosphate (ADP, 6.4 µM), arachidonic acid (ASPI, 0.5 mM), collagen (Col, 3.2 µg/ml), ristocetin (Risto, 0.2 mg/ml) and thrombin receptor-activating peptide (TRAP, 32 µM). PFA-100® was triggered by collagen/epinephrine and collagen/ADP. TG was assessed in platelet-poor plasma with 1 pM tissue factor and 4 µM phospholipids and without trigger. Data were analysed using a two-way mixed-effects model for the intraclass correlation (ICC) and by the Mann-Whitney U-test. MEA and PFA-100® revealed good correlation (ICC) between the sites. CTI inhibited TG significantly more effective than citrate. Contact activation was independent of the collection method. Only the MEA ASPI test revealed significant differences between the two collection methods. Blood sampling from all lines for MEA and PFA-100® assays is justified. Contact activation is always present. Apparently this does not influence platelet function test results. Collection methods do not seem relevant, although, one should always consider using a standardized method.

Mean platelet volume as a diagnostic marker for cardiovascular disease: drawbacks of preanalytical conditions and measuring techniques.

After the first description of platelets more than a century ago, the knowledge about their origin and function grew continuously. The development of the impedance method as a completely automated assay allowed integrating mean platelet volume (MPV) measurement as a routine parameter of the complete blood count. This enabled us to focus more on the association of platelet function and size. Since then, many authors described MPV as a marker of platelet reactivity and risk factor for cardiovascular diseases. Hence, the preanalytical variability of this parameter is known from its introduction as standard laboratory value. Unfortunately no preanalytical standards have been implemented. This review shows the high variability in the literature with MPV as a risk factor for cardiovascular disease. After a brief description of the biology of platelets, we provide an in-depth survey of the measurement methods and their drawbacks. Finally, we propose a possible approach to standardization.

Influence of erroneous patient records on population pharmacokinetic modeling and individual bayesian estimation.

BACKGROUND: Observational data sets can be used for population pharmacokinetic (PK) modeling. However, these data sets are generally less precisely recorded than experimental data sets. This article aims to investigate the influence of erroneous records on population PK modeling and individual maximum a posteriori Bayesian (MAPB) estimation. METHODS: A total of 1123 patient records of neonates who were administered vancomycin were used for population PK modeling by iterative 2-stage Bayesian (ITSB) analysis. Cut-off values for weighted residuals were tested for exclusion of records from the analysis. A simulation study was performed to assess the influence of erroneous records on population modeling and individual MAPB estimation. Also the cut-off values for weighted residuals were tested in the simulation study. RESULTS: Errors in registration have limited the influence on outcomes of population PK modeling but can have detrimental effects on individual MAPB estimation. A population PK model created from a data set with many registration errors has little influence on subsequent MAPB estimates for precisely recorded data. A weighted residual value of 2 for concentration measurements has good discriminative power for identification of erroneous records. CONCLUSIONS: ITSB analysis and its individual estimates are hardly affected by most registration errors. Large registration errors can be detected by weighted residuals of concentration.