Practical sources of error in measuring pulmonary artery occlusion pressure: a study in participants of a special intensivist training program of The Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI)

BACKGROUND: Physiological data obtained with the pulmonary artery catheter (PAC) are susceptible to errors in measurement and interpretation. Little attention has been paid to the relevance of errors in hemodynamic measurements performed in the intensive care unit (ICU). The aim of this study was to assess the errors related to the technical aspects (zeroing and reference level) and actual measurement (curve interpretation) of the pulmonary artery occlusion pressure (PAOP). METHODS: Forty-seven participants in a special ICU training program and 22 ICU nurses were tested without pre-announcement. All participants had previously been exposed to the clinical use of the method. The first task was to set up a pressure measurement system for PAC (zeroing and reference level) and the second to measure the PAOP. RESULTS: The median difference from the reference mid-axillary zero level was - 3 cm (-8 to + 9 cm) for physicians and -1 cm (-5 to + 1 cm) for nurses. The median difference from the reference PAOP was 0 mmHg (-3 to 5 mmHg) for physicians and 1 mmHg (-1 to 15 mmHg) for nurses. When PAOP values were adjusted for the differences from the reference transducer level, the median differences from the reference PAOP values were 2 mmHg (-6 to 9 mmHg) for physicians and 2 mmHg (-6 to 16 mmHg) for nurses. CONCLUSIONS: Measurement of the PAOP is susceptible to substantial error as a result of practical mistakes. Comparison of results between ICUs or practitioners is therefore not possible.

Increase in substance P precursor mRNA in noninflamed small-bowel sections in patients with Crohn's disease

BACKGROUND: Neuropeptides, such as substance P (SP), are mediators of neurogenic inflammation and play an important role in inflammatory disorders. To further investigate the role of the SP pathway in inflammatory bowel disease (IBD), we analyzed the following in normal intestinal tissue specimens and in tissue specimens from patients with Crohn's disease (CD) and ulcerative colitis (UC): neurokinin receptor-1 (NK-1R); its isoforms (NK-1R-L and NK-1R-S); its ligand SP, encoded by preprotachykinin-A (PPT-A); and the SP-degradation enzyme, neutral endopeptidase (NEP). METHODS: Real-time quantitative reverse transcription-polymerase chain reaction was used to simultaneously determine the expression of NK-1R-L, NK-1R-S, and PPT-A. Protein levels of NK-1R and NEP were determined by immunoblot analysis. RESULTS: In noninflamed small-bowel tissue samples of CD patients, PPT-A mRNA expression was significantly increased, whereas there was no difference between inflamed or noninflamed UC and normal intestinal tissue samples. Examining subgroups of diverse intestinal segments from CD and UC samples with various levels of inflammation revealed no differences in NK-1R-L and NK-1R-S mRNA expression, whereas there was a tendency toward overall lower NK-1R-S mRNA copy numbers. Immunoblot analysis showed upregulation of NK-1R protein levels in cases of IBD, with more pronounced enhancement in cases of CD than in UC. For NEP, there were no differences in protein levels in normal, CD, and UC intestinal tissues. COMMENTS: These observations suggest a contribution of SP and its receptor, NK-1R, in the local inflammatory reaction in IBD and particularly in ileal CD. Moreover, significant upregulation of PPT-A mRNA in the noninflamed ileum of these patients suggests an influence of inflamed intestines on their healthy counterparts.

Accounting for baseline differences and measurement error in the analysis of change over time

If change over time is compared in several groups, it is important to take into account baseline values so that the comparison is carried out under the same preconditions. As the observed baseline measurements are distorted by measurement error, it may not be sufficient to include them as covariate. By fitting a longitudinal mixed-effects model to all data including the baseline observations and subsequently calculating the expected change conditional on the underlying baseline value, a solution to this problem has been provided recently so that groups with the same baseline characteristics can be compared. In this article, we present an extended approach where a broader set of models can be used. Specifically, it is possible to include any desired set of interactions between the time variable and the other covariates, and also, time-dependent covariates can be included. Additionally, we extend the method to adjust for baseline measurement error of other time-varying covariates. We apply the methodology to data from the Swiss HIV Cohort Study to address the question if a joint infection with HIV-1 and hepatitis C virus leads to a slower increase of CD4 lymphocyte counts over time after the start of antiretroviral therapy.

The International ADHD in Substance Use Disorders Prevalence (IASP) study: background, methods and study population

Attention deficit/hyperactivity disorder (ADHD) is an increasingly recognized comorbid condition in subjects with substance use disorders (SUDs). This paper describes the methods and study population of the International ADHD in Substance Use Disorders Prevalence (IASP) study. Objectives of the IASP are to determine the prevalence of ADHD in adult treatment seeking patients with SUD in different countries and SUD populations, determine the reliability and validity of the Adult ADHD Self-report Scale V 1.1 (ASRS) as ADHD screening instrument in SUD populations, investigate the comorbidity profile of SUD patients with and without ADHD, compare risk factors and protective factors in SUD patients with and without a comorbid diagnosis of ADHD, and increase our knowledge about the relationship between ADHD and the onset and course of SUD. In this cross-sectional, multi-centre two stage study, subjects were screened for ADHD with the ASRS, diagnosed with the Conner's Adult ADHD Diagnostic Interview for DSM-IV (CAADID), and evaluated for SUD, major depression, bipolar disorder, anti social personality disorder and borderline personality disorder. Three thousand five hundred and fifty-eight subjects from 10 countries were included. Of these 40.9% screened positive for ADHD. This is the largest international study on this population evaluating ADHD and comorbid disorders.

Early developmental, temperamental and educational problems in ‘substance use disorder’ patients with and without ADHD. Does ADHD make a difference?

Introduction: The prevalence of ADHD among patients with substance use disorder (SUD) is substantial. This study addressed the following research questions: Are early developmental, temperamental and educational problems overrepresented among SUD patients with ADHD compared to SUD patients without ADHD? Do this comorbid group receive early help for their ADHD, and are there signs of self-medicating with illicit central stimulants? Method: An international, multi-centre cross-sectional study was carried out involving seven European countries, with 1205 patients in treatment for SUD. The mean age was 40 years and 27% of the sample was female. All par- ticipants were interviewed with the Mini International Neuropsychiatric Interview Plus and the Conners' Adult ADHD Diagnostic Interview for DSM-IV. Results: SUD patients with ADHD (n = 196; 16.3% of the total sample) had a significantly slower infant develop- ment than SUD patients without ADHD (n = 1,009; 83.4%), had greater problems controlling their temperament, and had lower educational attainment. Only 24 (12%) of the current ADHD positive patients had been diagnosed and treated during childhood and/or adolescence. Finally, SUD patients with ADHD were more likely to have central stimulants or cannabis as their primary substance of abuse, whereas alcohol use was more likely to be the primary substance of abuse in SUD patients without ADHD. Conclusion: The results emphasize the importance of early identification of ADHD and targeted interventions in the health and school system, as well as in the addiction field.

Variability in the prevalence of adult ADHD in treatment seeking substance use disorder patients: results from an international multi-center study exploring DSM-IV and DSM-5 criteria

Background: Available studies vary in their estimated prevalence of attention deficit/hyperactivity disor-der (ADHD) in substance use disorder (SUD) patients, ranging from 2 to 83%. A better understanding ofthe possible reasons for this variability and the effect of the change from DSM-IV to DSM-5 is needed.Methods: A two stage international multi-center, cross-sectional study in 10 countries, among patientsform inpatient and outpatient addiction treatment centers for alcohol and/or drug use disorder patients. Atotal of 3558 treatment seeking SUD patients were screened for adult ADHD. A subsample of 1276 subjects,both screen positive and screen negative patients, participated in a structured diagnostic interview. 5AdultsResults: Prevalence of DSM-IV and DSM-5 adult ADHD varied for DSM-IV from 5.4% (CI 95%: 2.4–8.3) forHungary to 31.3% (CI 95%:25.2–37.5) for Norway and for DSM-5 from 7.6% (CI 95%: 4.1–11.1) for Hungary to32.6% (CI 95%: 26.4–38.8) for Norway. Using the same assessment procedures in all countries and centersresulted in substantial reduction of the variability in the prevalence of adult ADHD reported in previousstudies among SUD patients (2–83% → 5.4–31.3%). The remaining variability was partly explained byprimary substance of abuse and by country (Nordic versus non-Nordic countries). Prevalence estimatesfor DSM-5 were slightly higher than for DSM-IV.Conclusions: Given the generally high prevalence of adult ADHD, all treatment seeking SUD patientsshould be screened and, after a confirmed diagnosis, treated for ADHD since the literature indicates poorprognoses of SUD in treatment seeking SUD patients with ADHD.

Psychiatric comorbidity in treatment-seeking substance use disorder patients with and without attention deficit hyperactivity disorder: results of the IASP study

Aims To determine comorbidity patterns in treatment-seeking substance use disorder (SUD) patients with and without adult attention deficit hyperactivity disorder (ADHD), with an emphasis on subgroups defined by ADHD subtype, taking into account differences related to gender and primary substance of abuse. Design Data were obtained from the cross-sectional International ADHD in Substance use disorder Prevalence (IASP) study. Setting Forty-seven centres of SUD treatment in 10 countries. Participants A total of 1205 treatment-seeking SUD patients. Measurements Structured diagnostic assessments were used for all disorders: presence of ADHD was assessed with the Conners' Adult ADHD Diagnostic Interview for DSM-IV (CAADID), the presence of antisocial personality disorder (ASPD), major depression (MD) and (hypo)manic episode (HME) was assessed with the Mini International Neuropsychiatric Interview-Plus (MINI Plus), and the presence of borderline personality disorder (BPD) was assessed with the Structured Clinical Interview for DSM-IV Axis II (SCID II). Findings The prevalence of DSM-IV adult ADHD in this SUD sample was 13.9%. ASPD [odds ratio (OR) = 2.8, 95% confidence interval (CI) = 1.8–4.2], BPD (OR = 7.0, 95% CI = 3.1–15.6 for alcohol; OR = 3.4, 95% CI = 1.8–6.4 for drugs), MD in patients with alcohol as primary substance of abuse (OR = 4.1, 95% CI = 2.1–7.8) and HME (OR = 4.3, 95% CI = 2.1–8.7) were all more prevalent in ADHD+ compared with ADHD− patients (P < 0.001). These results also indicate increased levels of BPD and MD for alcohol compared with drugs as primary substance of abuse. Comorbidity patterns differed between ADHD subtypes with increased MD in the inattentive and combined subtype (P < 0.01), increased HME and ASPD in the hyperactive/impulsive (P < 0.01) and combined subtypes (P < 0.001) and increased BPD in all subtypes (P < 0.001) compared with SUD patients without ADHD. Seventy-five per cent of ADHD patients had at least one additional comorbid disorder compared with 37% of SUD patients without ADHD. Conclusions Treatment-seeking substance use disorder patients with attention deficit hyperactivity disorder are at a very high risk for additional externalizing disorders.

Line bisection in simulated homonymous hemianopia

Hemianopic patients make a systematic error in line bisection, showing a contra-lesional bias towards their blind side, which is the opposite of that in hemineglect patients. This error has been attributed variously to the visual field defect, to long-term strategic adaptation, or to independent effects of damage to extrastriate cortex. To determine if hemianopic bisection error can occur without the latter two factors, we studied line bisection in healthy subjects with simulated homonymous hemianopia using a gaze-contingent display, with different line-lengths, and with or without markers at both ends of the lines. Simulated homonymous hemianopia did induce a contra-lesional bisection error and this was associated with increased fixations towards the blind field. This error was found with end-marked lines and was greater with very long lines. In a second experiment we showed that eccentric fixation alone produces a similar bisection error and eliminates the effect of line-end markers. We conclude that a homonymous hemianopic field defect alone is sufficient to induce both a contra-lesional line bisection error and previously described alterations in fixation distribution, and does not require long-term adaptation or extrastriate damage.

Frequency of and predictors for patient-reported medical and medication errors in Switzerland

OBJECTIVES: To analyse the frequency of and identify risk factors for patient-reported medical errors in Switzerland. The joint effect of risk factors on error-reporting probability was modelled for hypothetical patients. METHODS: A representative population sample of Swiss citizens (n = 1306) was surveyed as part of the Commonwealth Fund’s 2010 lnternational Survey of the General Public’s Views of their Health Care System’s Performance in Eleven Countries. Data on personal background, utilisation of health care, coordination of care problems and reported errors were assessed. Logistic regression analysis was conducted to identify risk factors for patients’ reports of medical mistakes and medication errors. RESULTS: 11.4% of participants reported at least one error in their care in the previous two years (8% medical errors, 5.3% medication errors). Poor coordination of care experiences was frequent. 7.8% experienced that test results or medical records were not available, 17.2% received conflicting information from care providers and 11.5% reported that tests were ordered although they had been done before. Age (OR = 0.98, p = 0.014), poor health (OR = 2.95, p = 0.007), utilisation of emergency care (OR = 2.45, p = 0.003), inpatient-stay (OR = 2.31, p = 0.010) and poor care coordination (OR = 5.43, p <0.001) are important predictors for reporting error. For high utilisers of care that unify multiple risk factors the probability that errors are reported rises up to p = 0.8. CONCLUSIONS: Patient safety remains a major challenge for the Swiss health care system. Despite the health related and economic burden associated with it, the widespread experience of medical error in some subpopulations also has the potential to erode trust in the health care system as a whole.

Evaluating the Impact of the Number of Access Points in Mobile Robots Localization Using Artificial Neural Networks

Localization is information of fundamental importance to carry out various tasks in the mobile robotic area. The exact degree of precision required in the localization depends on the nature of the task. The GPS provides global position estimation but is restricted to outdoor environments and has an inherent imprecision of a few meters. In indoor spaces, other sensors like lasers and cameras are commonly used for position estimation, but these require landmarks (or maps) in the environment and a fair amount of computation to process complex algorithms. These sensors also have a limited field of vision. Currently, Wireless Networks (WN) are widely available in indoor environments and can allow efficient global localization that requires relatively low computing resources. However, the inherent instability in the wireless signal prevents it from being used for very accurate position estimation. The growth in the number of Access Points (AP) increases the overlap signals areas and this could be a useful means of improving the precision of the localization. In this paper we evaluate the impact of the number of Access Points in mobile nodes localization using Artificial Neural Networks (ANN). We use three to eight APs as a source signal and show how the ANNs learn and generalize the data. Added to this, we evaluate the robustness of the ANNs and evaluate a heuristic to try to decrease the error in the localization. In order to validate our approach several ANNs topologies have been evaluated in experimental tests that were conducted with a mobile node in an indoor space.

Information processing in long delay memory-guided saccades: further insights from TMS

The performance of memory-guided saccades with two different delays (3 s and 30 s of memorisation) was studied in eight subjects. Single pulse transcranial magnetic stimulation (TMS) was applied simultaneously over the left and right dorsolateral prefrontal cortex (DLPFC) 1 s after target presentation. In both delays, stimulation significantly increased the percentage of error in amplitude of memory-guided saccades. Furthermore, the interfering effect of TMS was significantly higher in the short delay compared to that of the long delay paradigm. The results are discussed in the context of a mixed model of spatial working memory control including two components: First, serial information processing with a predominant role of the DLPFC during the early period of memorisation and, second, parallel information processing, which is independent from the DLPFC, operating during longer delays.

Saccadic eye movement disturbances in whiplash patients with persistent complaints.

In order to analyse the possible basis of subjective complaints following whiplash injury, horizontal eye movements were examined in subjects with persistent complaints ('symptomatic group') and subjects who had completely recovered ('recovered group'). The results for the symptomatic and recovered groups were compared with those for age-matched, healthy volunteers (control group). A battery of different saccade paradigms was employed: two were reflexive saccade tasks including a gap and an overlap task, and two were intentional saccade tasks consisting of an antisaccade and a memory-guided saccade task. In addition, the symptomatic and recovered groups also underwent psychiatric evaluation in a structured clinical interview, and all groups were assessed for emotional functioning using the Beck Depression Inventory (BDI). The recovered group did not differ significantly from the control group in saccade performance and emotional functioning. The symptomatic group showed dissociation of their performances of reflexive and intentional saccade tasks: performance in reflexive saccade tasks was normal, but in intentional saccade tasks the symptomatic group showed significantly impaired inhibition of unwanted reflexive saccades, impaired saccade triggering (i.e. increased latency) and a higher percentage error in amplitude in memory-guided saccades. Based on clinical interviews, no signs of major depression or dysthymia were found in any of the groups. Compared with the other two groups, the symptomatic group had significantly higher overall BDI scores, but these resulted from BDI dimensions that were non-specific to depression, viz. 'physiological manifestations' (e.g. fatigue, sleep disturbance) or 'performance difficulty' (e.g. work inhibition). In summary, in the symptomatic group the pattern of eye movement disturbances together with normal performance in reflexive saccade tasks and impaired performance in the intentional saccade tasks, especially impaired inhibitory function, suggests dysfunction of prefrontal and frontal cortical structures.