Analysis of cardiovascular oscillations: a new approach to the early prediction of pre-eclampsia

Pre-eclampsia (PE) is a serious disorder with high morbidity and mortality occurring during pregnancy; 3%-5% of all pregnant women are affected. Early prediction is still insufficient in clinical practice. Although most pre-eclamptic patients show pathological uterine perfusion in the second trimester, this parameter has a positive predictive accuracy of only 30%, which makes it unsuitable for early, reliable prediction. The study is based on the hypothesis that alterations in cardiovascular regulatory behavior can be used to predict PE. Ninety-six pregnant women in whom Doppler investigation detected perfusion disorders of the uterine arteries were included in the study. Twenty-four of these pregnant women developed PE after the 30th week of gestation. During pregnancy, additional several noninvasive continuous blood pressure recordings were made over 30 min under resting conditions by means of a finger cuff. The time series extracted of systolic as well as diastolic beat-to-beat pressures and the heart rate were studied by variability and coupling analysis to find predictive factors preceding genesis of the disease. In the period between the 18th and 26th weeks of pregnancy, three special variability and baroreflex parameters were able to predict PE several weeks before clinical manifestation. Discriminant function analysis of these parameters was able to predict PE with a sensitivity and specificity of 87.5% and a positive predictive value of 70%. The combined clinical assessment of uterine perfusion and cardiovascular variability demonstrates the best current prediction several weeks before clinical manifestation of PE.

Joint symbolic dynamic analysis of cardiorespiratory interactions in patients on weaning trials

Assessing autonomic control provides information about patho-physiological imbalances. Measures of variability of the cardiac interbeat duration RR(n) and the variability of the breath duration T<inf>Tot</inf>(n) are sensitive to those changes. The interactions between RR(n) and T<inf>Tot</inf>(n) are complex and strongly non-linear. A study of joint symbolic dynamics is presented as a new short-term non-linear analysis method to investigate these interactions in patients on weaning trials. 78 patients from mechanical ventilation are studied: Group A (patients that failed to maintain spontaneous breathing and were reconnected) and Group B (patients with successful trials). Using the concept of joint symbolic dynamics, cardiac and respiratory changes were transformed into a word series, and the probability of occurrence of each word type was calculated and compared between both groups. Significant differences were found in 13 words, and the most significant p<inf>n</inf>(W<inf>c010, r010</inf>): 0.0041 &#177; 0.0036 (group A) against 0.0012 &#177; 0.0024 (group B), p-value = 0.00001. The number of seldom occurring word types (forbidden words) also presents significant differences fw<inf>cr</inf>: 6.9 &#177; 6.6 against 13.5 &#177; 5.3, p-value = 0.00004. Joint symbolic dynamics provides an efficient non-linear representation of cardiorespiratory interactions that offers simple physiological interpretations.

How many infection control staff do we need in hospitals?

During a one-day workshop experienced infection control practitioners (ICPs) and medical microbiologists debated how much time was needed for the delivery of infection control activities in a model hospital. They agreed a standard of one full-time equivalent (FTE) ICP per 178 hospital beds and one FTE medical microbiologist per 806 hospital beds. This is 40% and 24% more than the usual standard, respectively. Now that official numbers of hospital beds have become an inadequate parameter for work delivered by hospitals, a new standard is proposed, with the number of admissions as the denominator. This is one FTE ICP per 5000 admissions and one medical microbiologist or epidemiologist per 25000 admissions.

Detection of a new SHV-type extended-spectrum beta-lactamase, SHV-31, in a Klebsiella pneumoniae strain causing a large nosocomial outbreak in The Netherlands

A Klebsiella pneumoniae strain resistant to third-generation cephalosporins was isolated in the eastern Netherlands. The strain was found to carry a novel extended-spectrum beta-lactamase, namely, SHV-31. The combination of the two mutations by which SHV-31 differs from SHV-1, namely, L35Q and E240K, had previously only been described in association with one or more additional mutations.

Linear and nonlinear methods for analyses of cardiovascular variability in bipolar disorders

OBJECTIVES

Heart rate variability (HRV), blood pressure variability (BPV), and the assessment of baroreflex sensitivity are widely accepted methods for analyzing and characterizing cardiovascular regulation and for an enhanced risk evaluation in different diseases. As a result of the complexity of the investigated regulatory systems, univariate analyses do not often provide a convenient description of pathological changes in the cardiovascular regulation. Therefore, the application of a multivariate approach is preferable.

METHODS

We present principal methods of time-domain, frequency-domain, and nonlinear analyses of HRV, BPV as well as methods for coupling and interaction analyses.

RESULTS

Changes in autonomic nervous system (ANS) tone are known to accompany various mental disorders. Depressive patients frequently complain of symptoms of ANS dysfunction, such as dry mouth, diarrhea, and insomnia. These clinical observations propose the assumption of altered autonomic dysfunction in these patients. In contrast to these clinical assumptions, inconsistent results have been found in studies of HRV in depressive patients. This work therefore covers a brief review of the literature in respect to bipolar disorder and the rationale to study autonomic changes in such a psychiatric disease.

CONCLUSIONS

Prospective studies of cardiovascular changes in mania and depression are needed to evaluate a psychopathological state in connection with cardiovascular changes and cardiac morbidity and mortality. These studies should consider BPV, coupling and interaction analyses, the application of nonlinear methods, and a multivariate approach in addition to the traditional analysis of HRV.

Status of infection control policies and organisation in European hospitals, 2001: the ARPAC study

Patient safety in hospital care depends on effective infection control (IC) programmes. The Antimicrobial Resistance Prevention and Control (ARPAC) study assessed the organisation, components and human resources of IC programmes in European hospitals. A questionnaire survey of policies and procedures implemented in 2001 for the surveillance and control of nosocomial infection and antibiotic resistance was completed by 169 acute-care hospitals from 32 European countries, categorised by five geographical regions. A formal IC programme existed in 72% of hospitals, and a multidisciplinary IC committee was operational in 90%. Trained IC nurses (ICNs) were present in 80% of hospitals (ranging from 54% in south-east and central-eastern Europe, to 100% in northern Europe), whereas 74% had one or more trained IC doctors (ICDs) (ranging from 46% in south-east Europe to 84% in western Europe). Median staffing levels were 2.33 ICNs/1,000 beds and 0.94 ICDs/1,000 beds. The intensity of IC programmes scored higher in centres from northern and western Europe than from other European regions. Written guidelines promoted hand hygiene for healthcare workers in 89% of hospitals, education in 85%, and audit in 46%. Guidelines recommended use of alcohol-based solutions (70%) and/or medicated/antiseptic soap (43%) for decontamination of non-soiled hands. Use of alcohol-based solutions varied according to region, from 41% in southern Europe to 100% in northern Europe, compared with use of medicated soap from 77% in southern Europe to 11% in northern Europe (p < 0.01). These findings showed that IC programmes in European hospitals suffer from major deficiencies in human resources and policies. Staffing levels for ICNs were below recommended standards in the majority of hospitals. Education programmes were incomplete and often not supported by audit of performance. Hand hygiene procedures were sub-standard in one-third of centres. Strengthening of IC policies in European hospitals should be a public health priority.

Trends in fungaemia and antifungal susceptibility in the Netherlands

We retrospectively evaluated fungaemia over the period 1996 to 2001 in five university hospitals. Over 350,000 blood cultures were collected during more than 7 million days of hospitalisation. The average rate of fungaemia over the six-year period was 0.82 per 10,000 patient days (range 0.65 to 1.21 per 10,000 patient days). The proportion of bloodstream infections caused by Candida albicans remained stable throughout the study period with a mean of 53% (range 48 to 62%). This is a change from trends described in previous studies, including a survey performed in the Netherlands. This study shows a new, stable rate of fungaemia and no further signs of increasing rate of infections due to non-albicans Candida species. Susceptibility to all tested antifungal agents remained stable throughout the study period.

Quality control for handling of accidental blood exposures

A regional counselling service was established to handle all accidental blood exposures using a standardized protocol. Levels of risk were assessed using an algorithm. Accidents that posed a risk for the transmission of hepatitis B (HBV), hepatitis C (HCV) and human immunodeficiency virus (HIV) were classified as 'high risk', whereas accidents that posed a risk for HBV alone were classified as 'low risk'. Medical interventions were implemented according to the level of risk. During a one-year period, all accidents were registered and analysed for adherence to the standard protocol. In 2003, the centre handled 454 incidents. Of these, 36 (7.9%) incidents were assessed as no risk, 329 (72.5%) were assessed as low risk, and 67 (14.8%) were assessed as high risk. Due to incomplete registration, 22 (4.8%) incidents could not be analysed further. In total, 36% of the incidents with risk for HBV transmission and 40% of the incidents with risk for HCV and HIV transmission were not handled according to the proposed protocol. Breaches consisted of over-reaction (25/396) as well as insufficient response (123/396). Potentially inadequate treatment occurred for HIV postexposure prophylaxis in 12 of 63 incidents. Incomplete follow-up for HCV occurred in 11 of 63 incidents, and lack of HBV immunoglobulin administration occurred in five of 396 incidents, including three high-risk incidents. In 21 of 396 low-risk exposures, the breaches in protocol resulted from late reporting. It remains difficult to achieve an acceptable level of standardized care when using standard operational procedures. Documentation and evaluation of flaws are essential to improve the system.

[Scabies outbreak in a hospital and in 8 health-care institutions caused by an elderly patient with scabies crustosa]

An outbreak of scabies in a teaching hospital, two nursing homes and six health-care institutions for the elderly, occurred in the Nijmegen area in the Netherlands, between September 2004 and April 2005. In November 2004 the diagnosis of scabies crustosa (scabies norvegica) was made in the index patient - a 78-year-old woman. An atypical presentation, without much itching, as is not infrequently seen in elderly patients, resulted in there being a considerable delay before the diagnosis was made. This resulted in a total of 51 people, both in and outside the hospital, becoming infected. Based on article 7 of the Dutch Infectious Diseases Act, the Municipal Health Service (GGD) advised institutions on the policy and carried out both source and contact tracing. According to this Act notification and cooperation between hospital, care institutions and the GGD are of importance for the effective handling of epidemics. Systemic treatment with ivermectin is the main alternative to local treatment in outbreaks in institutions.

Differences between Hospital- and Community-Acquired Blood Exposure Incidents Revealed by a Regional Expert Counseling Center

OBJECTIVE

One year (2003) regional analysis of all blood exposure incidents from hospitals as well as from the community.

DESIGN

Establishment of an easily accessible regional expert counseling center, operating 24 h a day, for all accidental blood exposures. Tasks of the center were to register incoming calls, to inform and counsel the victim, to assess the risk of the incident, and to provide a plan of further actions, including prophylactic measures.

SETTING

A Dutch region (Northeast Brabant) with 500,000 inhabitants and two major hospitals (1,786 beds).

RESULTS

A total of 454 incidents (1.2 per day) were recorded. Only half of the incidents occurred in the hospital setting (n = 234), whereas the others (n = 220) took place in the community setting. Nearly all (95%, n = 432) incidents occurred during work, and most of them (84%, n = 385) were related to health care activities. In the hospital setting injuries occurred with physicians (13%), nursing staff (45%), operating room (OR) staff (13%), ancillary (18%), others (10%). In the community setting, incidents took place among healthcare workers (48%), detention and police officers (10%), civilians (10%), general practitioners/dentists and their staff (8%), cleaning staff (4%) and work-related incidents not falling into any of the above categories (7%). More low risk incidents took place outside the hospital (87% vs. 68% in hospital), while high-risk incidents predominantly occurred within the hospital setting (23% vs. 6%). The hepatitis-B immunization rate was significantly lower in victims from the community than in those working in hospitals (38% vs. 96%). Reports from incidents in the community setting were delayed.

CONCLUSIONS

Incidents that expose individuals to blood-borne pathogens occur equally frequent in the hospital and non-hospital (community) setting. Therefore, a regional expert counseling center, accessible around-the-clock, for all types of blood-exposure incidents is needed. Blood-exposure prevention programs should aim at a reduction of high-risk incidents within hospitals, and at increasing the awareness for vaccination and early reporting within the community setting.

Random effect modelling of patient-related risk factors in orthopaedic procedures: results from the Dutch nosocomial infection surveillance network 'PREZIES'

In the Dutch surveillance for surgical site infections (SSIs), data from 70277 orthopaedic procedures with 1895 SSIs were collected between 1996 and 2003. The aims of this study were: (1) to analyse the trends in SSIs associated with Gram-positive and Gram-negative bacteria; (2) to estimate patient-related risk factors for deep and superficial SSIs after all orthopaedic procedures, with special attention to primary total hip arthroplasty (THA); and (3) to analyse inherent differences in infection risk between hospitals. A random effect model was used to estimate the odds ratios of patient-related risk factors for developing an SSI, and to describe the distribution of the most widespread bacterial species responsible for SSIs among hospitals. Gram-positive organisms, mainly staphylococci, were the main cause of both deep (84.0%) and superficial SSIs (69.1%) after orthopaedic procedures. The percentage of SSIs after THA caused by coagulase-negative staphylococci decreased over the surveillance period, while the contribution of Staphylococcus aureus increased. Temporary elevations in the incidence of the most widespread pathogen species were observed within hospitals. Patient-related factors such as the National Nosocomial Infections Surveillance System risk index or age had little effect on the predictive power of the random effect models. This study underlines the usefulness of a random effect model, which adjusts risk estimates for random variation between hospitals, in a multicentre study on risk factors for SSIs.

Hidden Markov Models Based on Symbolic Dynamics for Statistical Modeling of Cardiovascular Control in Hypertensive Pregnancy Disorders

Discrete hidden Markov models (HMMs) were applied to classify pregnancy disorders. The observation sequence was generated by transforming RR and systolic blood pressure time series using symbolic dynamics. Time series were recorded from 15 women with pregnancy-induced hypertension, 34 with preeclampsia and 41 controls beyond 30th gestational week. HMMs with five to ten hidden states were found to be sufficient to characterize different blood pressure variability, whereas significant classification in RR-based HMMs was found using fifteen hidden states. Pregnancy disorders preeclampsia and pregnancy induced hypertension revealed different patho-physiological autonomous regulation supposing different etiology of both disorders.

Optimized Symbolic Dynamics Approach for the Analysis of the Respiratory Pattern

Traditional time domain techniques of data analysis are often not sufficient to characterize the complex dynamics of respiration. In this paper, the respiratory pattern variability is analyzed using symbolic dynamics. A group of 20 patients on weaning trials from mechanical ventilation are studied at two different pressure support ventilation levels, in order to obtain respiratory volume signals with different variability. Time series of inspiratory time, expiratory time, breathing duration, fractional inspiratory time, tidal volume and mean inspiratory flow are analyzed. Two different symbol alphabets, with three and four symbols, are considered to characterize the respiratory pattern variability. Assessment of the method is made using the 40 respiratory volume signals classified using clinical criteria into two classes: low variability (LV) or high variability (HV). A discriminant analysis using single indexes from symbolic dynamics has been able to classify the respiratory volume signals with an out-of-sample accuracy of 100%.

Dutch Guideline for Preventing Nosocomial Transmission of Highly Resistant Microorganisms (HRMO)

Hospitals are faced with the increasingly rapid emergence and dissemination of antimicrobial-resistant microorganisms. US and European guidelines on the prevention of antimicrobial resistance in hospitals were, until recently, mainly directed at methicillin-resistant Staphylococcus aureus (MRSA). In 2004, the Dutch Working Party on Infection Prevention issued a guideline on the prevention of nosocomial transmission of highly resistant microorganisms (HRMO), in order to fulfill the growing need for additional guidance on the control of other pathogens with acquired resistance and the potential to spread within hospitals (such as glycopeptide-resistant Enterococcus faecium, penicillin-resistant Streptococcus pneumoniae, extendedspectrum beta-lactamase producing Enterobacteriaceae, and other (multi)drug-resistant gram-negatives). In addition to providing criteria for defining HRMO, the Dutch guideline provides recommendations on isolation of patients, active surveillance, and contact tracing. The guideline will enable the comparison of HRMO rates between hospitals, and may be used to evaluate the efficacy of programs to control antibiotic use and/or nosocomial transmission of resistant pathogens. The eventual success of nationwide implementation of this guideline remains to be established in the coming years.