Erik H. Korsten

Contrast echocardiography for pulmonary blood volume quantification

Pulmonary blood volume quantification is important both for diagnosis and for monitoring of the circulatory system. It requires employment of transpulmonary indicator dilution techniques, which are very invasive due to the need for double catheterization. This paper presents a new minimally invasive technique for blood volume quantification. An ultrasound contrast agent bolus is injected peripherally and detected by an ultrasound transducer in the central circulation. Several echocardiographic views permit simultaneous detection of contrast in different cardiac cavities and central vessels, and acoustic backscatter measurements produce multiple indicator dilution curves (IDCs). Contrast mean-transit-time differences are derived from the IDC analysis and multiplied times cardiac output for the assessment of blood volumes between different detection sites. For pulmonary blood volume estimates, the right ventricle and the left atrium IDCs are measured. The mean transit time of the IDC is estimated by specific modelling. The Local Density Random Walk and the First Passage Time models were tested for IDC interpolation and interpretation. The system was validated in vitro for a wide range of flows. The results show very accurate volume measurements. The volume estimate determination coefficient is greater than 0.999 for both model fits. A preliminary study in patients shows promising results.

Videodensitometric methods for cardiac output measurements

Cardiac output is often measured by indicator dilution techniques, usually based on dye or cold saline injections. Developments of more stable ultrasound contrast agents (UCA) are leading to new noninvasive indicator dilution methods. However, several problems concerning the interpretation of dilution curves as detected by ultrasound transducers have arisen. This paper presents a method for blood flow measurements based on UCA dilution. Dilution curves are determined by real-time densitometric analysis of the video output of an ultrasound scanner and are automatically fitted by the Local Density Random Walk model. A new fitting algorithm based on multiple linear regression is developed. Calibration, that is, the relation between videodensity and UCA concentration, is modelled by in vitro experimentation. The flow measurement system is validated by in vitro perfusion of SonoVue contrast agent. The results show an accurate dilution curve fit and flow estimation with determination coefficient larger than 0.95 and 0.99, respectively.

Physicians' responses to clinical decision support on an intensive care unit-Comparison of four different alerting methods

BACKGROUND In intensive care environments, technology is omnipresent whereby ensuring constant monitoring and the administration of critical drugs to unstable patients. A clinical decision support system (CDSS), with its widespread possibilities, can be a valuable tool in supporting adequate patient care. However, it is still unclear how decision support alerts should be presented to physicians and other medical staff to ensure that they are used most effectively. OBJECTIVE To determine the effect of four different alert presentation methods on alert compliance after the implementation of an advanced CDSS on the intensive care unit (ICU) in our hospital. METHODS A randomized clinical trial was executed from August 2010 till December 2011, which included all patients admitted to the ICU of our hospital. The CDSS applied contained a set of thirteen locally developed clinical rules. The percentage of alert compliance was compared for four alert presentation methods: pharmacy intervention, physician alert list, electronic health record (EHR) section and pop-up alerts. Additionally, surveys were held to determine the method most preferred by users of the CDSS. RESULTS In the study period, the CDSS generated 902 unique alerts, primarily due to drug dosing during decreased renal function and potassium disturbances. Alert compliance was highest for recommendations offered in pop-up alerts (41%, n=68/166), followed by pharmacy intervention (33%, n=80/244), the physician alert list (20%, n=40/199) and the EHR section (19%, n=55/293). The method most preferred by clinicians was pharmacy intervention, and pop-up alerts were found suitable as well if applied correctly. The physician alert list and EHR section were not considered suitable for CDSSs in the process of this study. CONCLUSION The alert presentation method used for CDSSs is crucial for the compliance with alerts for the clinical rules and, consequently, for the efficacy of these systems. Active alerts such as pop-ups and pharmacy intervention were more effective than passive alerts, which do not automatically appear within the clinical workflow. In this pilot study, ICU clinicians also preferred pharmacy intervention and pop-up alerts. More research is required to expand these results to other departments and other hospitals, as well as to other types of CDSSs and different alert presentation methods.

Recurrence of adverse drug reactions following inappropriate re-prescription: better documentation, availability of information and monitoring are needed.

Adverse drug reactions (ADRs) are a common, and often preventable, cause of hospital admission, especially in the elderly, and can occur during hospitalization.In this current opinion article, we present three cases of recurrence of a serious ADR due to re-prescription of a withdrawn medication that highlight the need for a system to prevent the undesirable re-prescription of medications withdrawn because of an ADR. In addition, we describe an electronic system that could help prevent undesirable re-prescription following an ADR. Such a system should document ADRs systematically at the patient level, make this information available to relevant healthcare providers and the patient, and flag re-prescription of the offending drug. The effectiveness and cost effectiveness of such a system would need to be determined.

Reasons for Discontinuation of Medication During Hospitalization and Documentation Thereof: A Descriptive Study of 400 Geriatric and Internal Medicine Patients

attending physician’s name on a dry erase board, only 5 (10%; 95% CI, 3%-22%) were able to correctly identify the name of their attending physician. There was very strong evidence that this proportion was higher for patients with visual representation of their attending physician’s name (P .001), of whom 94 of 96 patients (98%; 95% CI, 93%-100%) were able to correctly identify their attending physician’s name. This indicates that compared with patients with no visual representation, the proportion of patients who were correctly able to identify the name of their attending physician was 88% higher (95% CI, 76%-94%) for patients with visual representation of their attending physician’s name in their room. Of note, of the 4 excluded patients for whom the attending physician’s name was not written on the dry erase board, none were able to correctly identify the name of that physician.

Systems that prevent unwanted represcription of drugs withdrawn because of adverse drug events: a systematic review

Represcription of medication that was withdrawn after the occurrence of an adverse drug event (including allergy), is a recognized medication safety issue on a patient level. We performed a systematic review to identify systems (electronic and nonelectronic) that can prevent the represcription of drugs withdrawn because of an adverse drug event and the effects of these systems. The review was performed using PRISMA and Cochrane guidelines. PubMed and Embase were searched for articles describing systems that can prevent represcription of drugs that had been withdrawn for causing an adverse drug event. Information on the characteristics of the studies, systems, and if present results achieved with such systems, was extracted. The results showed that of 6793 articles screened, 137 full-text articles were assessed for eligibility. A total of 45 studies describing 33 systems (28 electronic) were included. The five nonelectronic systems used allergy bracelets or allergy labels on hospital medical records or on drug orders. Systems differed in the way adverse drug events were documented and how users were alerted to drug represcription. Most systems functioned within a specific healthcare setting. Of 12 studies that compared pre- and post-intervention periods or wards with and without intervention, 7 showed a reduction in represcription after adverse drug event. In conclusion, several systems have been developed that can prevent the represcription of drugs that elicited an adverse drug event, but the evidence that these systems are effective is limited.

Preventive Prescribing of Laxatives for Opioid-induced Constipation Using Electronic Clinical Rule Implementation by Cinical Pharmacists

Objective: The objective of this study was: (1) to develop and validate an electronic clinical rule for ‘Opioid-Laxative Use’ and to implement this rule in clinical pharmacy practice; (2) to improve guideline compliance by using this refined clinical rule; and (3) to investigate if opioid-induced constipation (OIC) can be reduced in hospitalised patients by the application of this clinical rule. Methods: Interventions using clinical rule alerts were performed between June and September 2009. We compared guideline compliance before and after the intervention to determine the difference. Interventions consisted of telephone consultations by a clinical pharmacist advising physicians to add a laxative to opioid therapy. Patient files were matched to a historical control group using an opioid without a laxative to examine the difference between intervention- and control patients in the presence of OIC. Results: Prospective validation of the rule resulted in several refinements. In the intervention period, 140 alerts were generated, 60 of which (43%) led to co-prescription of a laxative. Therefore, guideline compliance increased from 70% to 83%. A significant difference in OIC was found between the intervention group (12%) and the control group (56%). Conclusions: This study showed that pharmacy intervention based on an electronic clinical rule for ´Opioid-Laxative Use´ led to more adequate co-prescription of opioids and laxatives. This led to a better compliance with the guideline as well as a better outcome, as measured by the significant decrease in the prevalence of OIC.

Strategy for development and pre-implementation validation of effective clinical decision support

Objective Well-designed clinical decision support systems (CDSS) can reduce the problem of alert fatigue by generating patient-specific alerts. This paper describes a strategy for the development and pre-implementation validation of specific and relevant clinical rules in order to reduce alert fatigue. Methods A four-step development and validation strategy of clinical rules is presented. As an example, from March to September 2006 the ‘lithium therapy rule’ was developed with this strategy based on the Plan-Do-Check-Act cycle. 15 368 patients were retrospectively screened and 2503 patients were prospectively screened while the positive and negative predictive values (PPV/NPV) were continuously monitored. The first step is to confirm that the parameters used in the definitions are linked to the correct data in the electronic health record; the second step involves an expert team in the review process to assure that alerts generated are clinically relevant; in the third step the rule is adjusted to generate the right alerts in daily practice; and the fourth step ensures technical and therapeutic maintenance after implementation in practice. Results From September 2006 to July 2010 nine other rules were developed following exactly the same strategy. The 10 clinical rules developed showed a progression during the development and all resulted in a final therapeutic PPV of ≥89% before implementation, based on expert opinion. NPV was determined for five clinical rules and was always 100%. Conclusions The proposed strategy is effective for creating specific and reliable clinical rules that generate relevant recommendations. The inclusion of an expert team in the development process is an essential success factor. It is hoped that it will accelerate the widespread use of these promising decision support systems in practice.

Success factors and barriers for implementation of advanced clinical decision support systems

Ten years ago, the US Institute of Medicine (IOM) called for a massive redesign of the healthcare delivery system.(Committee on Quality of Health Care in America, 2001) Today it is clear that one of the goals, the nationwide use of an electronic medical record (EMR) by 2010, has failed to be reached as the process of adoption has been slow. Some may consider an EMR as a final destination, although in fact it is only the start point of a revolution in healthcare: the implementation of clinical decision support systems (CDSS) that ‘make it easy to do it right’.(James, 2001) These systems are able to address the large, potential additional value of the implementation of an EMR. When an EMR is available, this is already a step in the right direction, to have an easy and structured access to all patient data available for all healthcare professionals that need them. However, this is still a huge amount of data, but one should also have the ability to integrate all these data and use these data in making the right choices in therapy. Practice has shown that despite the availability of an EMR, still many medication errors are made. Therefore, CDSS are designed to aid clinical decision-making by matching patient characteristics to a computerized knowledge or rule base to generate patient-specific recommendations.(Kawamoto et al., 2005) In the trendsetting IOM reports ‘To Err is Human’ (2000) and ‘Crossing the quality chasm’ (2001), a CDSS was endorsed as one of the most powerful tools available for improving patient safety and healthcare quality.(Kohn et al., 2000;Committee on Quality of Health Care in America, 2001) It is difficult to accept that despite multiple opportunities and promising results, these systems instead of being common practice, still remain ‘next-generation’.(James, 2001) During the last five years, research gave more insight in the success factors that could accelerate the idle process of CDSS adoption. (Kawamoto et al., 2005; Garg et al., 2005;Nies et al., 2006) The conclusions however are not univocal because the reviews included a wide variety of systems ranging from computerised to non-computerised CDSS as well as from basic to advanced systems. Basic decision support includes checking on drug-drug interactions, duplicate therapy, drug-allergies and generalized drug dosing. Advanced CDSS, used in addition to basic CDSS, includes for example checking on contra-indications (disease and drugs), individualized dosing support during renal impairment or guidance

Calculation of the Permeability Coefficient Should Take into Account the Fact That Most Drugs Are Weak Electrolytes

To the Editor:—Although I accept that the cleansing and sterilization of laryngoscope blades is a nuisance to nurses and other paramedical personnel, I do not think that the use of a condom to cover the laryngoscope blade is an answer to this problem. First, the condom cannot be assumed to be a barrier against the transmission of infection between cases. Damage to its integrity unnoticable by the naked eye can easily occur, particularly during contact with teeth or dental work in a difficult intubation. It is not an effective barrier and puts patients at risk of cross-contamination. Condoms are renowned for splitting when used for their intended purpose, and this is far more likely when used as described. Second, I also feel strongly that condom packets scattered around anesthetic rooms or empty packets in disposal bins will lead to anxiety among patients. Difficulty would also be encountered if patients inquire why an odd taste persists after anesthesia. I would certainly not like to be responsible for telling them not to worry—that is only the taste of the spermicidal jelly.