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PubMed2001

The measurement and monitoring of surgical adverse events.

BACKGROUND: Surgical adverse events contribute significantly to postoperative morbidity, yet the measurement and monitoring of events is often imprecise and of uncertain validity. Given the trend of decreasing length of hospital stay and the increase in use of innovative surgical techniques--particularly minimally invasive and endoscopic procedures--accurate measurement and monitoring of adverse events is crucial. OBJECTIVES: The aim of this methodological review was to identify a selection of common and potentially avoidable surgical adverse events and to assess whether they could be reliably and validly measured, to review methods for monitoring their occurrence and to identify examples of effective monitoring systems for selected events. This review is a comprehensive attempt to examine the quality of the definition, measurement, reporting and monitoring of selected events that are known to cause significant postoperative morbidity and mortality. METHODS - SELECTION OF SURGICAL ADVERSE EVENTS: Four adverse events were selected on the basis of their frequency of occurrence and likelihood of evidence of measurement and monitoring: (1) surgical wound infection; (2) anastomotic leak; (3) deep vein thrombosis (DVT); (4) surgical mortality. Surgical wound infection and DVT are common events that cause significant postoperative morbidity. Anastomotic leak is a less common event, but risk of fatality is associated with delay in recognition, detection and investigation. Surgical mortality was selected because of the effort known to have been invested in developing systems for monitoring surgical death, both in the UK and internationally. Systems for monitoring surgical wound infection were also included in the review. METHODS - LITERATURE SEARCH: Thirty separate, systematic literature searches of core health and biomedical bibliographic databases (MEDLINE, EMBASE, CINAHL, HealthSTAR and the Cochrane Library) were conducted. The reference lists of retrieved articles were reviewed to locate additional articles. A matrix was developed whereby different literature and study designs were reviewed for each of the surgical adverse events. Each article eligible for inclusion was independently reviewed by two assessors. METHODS - CRITICAL APPRAISAL: Studies were appraised according to predetermined assessment criteria. Definitions and grading scales were assessed for: content, criterion and construct validity; repeatability; reproducibility; and practicality (surgical wound infection and anastomotic leak). Monitoring systems for surgical wound infection and surgical mortality were assessed on the following criteria: (1) coverage of the system; (2) whether or not denominator data were collected; (3) whether standard and agreed definitions were used; (4) inclusion of risk adjustment; (5) issues related to data collection; (6) postdischarge surveillance; (7) output in terms of feedback and wider dissemination. RESULTS - SURGICAL WOUND INFECTION: A total of 41 different definitions and 13 grading scales of surgical wound infection were identified from 82 studies. Definitions of surgical wound infection varied from presence of pus to complex definitions such as those proposed by the Centres for Disease Control in the USA. A small body of literature has been published on the content, criterion and construct validity of different definitions, and comparisons have been made against wound assessment scales and multidimensional indices. There are examples of comprehensive hospital-based monitoring systems of surgical wound infection, mainly under the auspices of nosocomial surveillance. To date, however, there is little evidence of systematic measurement and monitoring of surgical wound infection after hospital discharge. RESULTS - ANASTOMOTIC LEAK: Over 40 definitions of anastomotic leak were extracted from 107 studies of upper gastrointestinal, hepatopancreaticobiliary and lower gastrointestinal surgery. No formal evaluations were found that assessed the validity or reliability of definitions or severity scales of anastomotic leak. One definition was proposed during a national consensus workshop, but no evidence of its use was found in the surgical literature. The lack of a single definition or gold standard hampers comparison of postoperative anastomotic leak rates between studies and institutions. RESULTS - DEEP VEIN THROMBOSIS: Although a critical review of the DVT literature could not be completed within the realms of this review, it was evident that a number of new techniques for the detection and diagnosis of DVT have emerged in the last 20 years. The group recommends a separate review be undertaken of the different diagnostic tests to detect DVT. RESULTS - SURGICAL MORTALITY MONITORING SYSTEMS: The definition of surgical mortality is relatively consistent between monitoring systems, but duration of follow-up of death postdischarge varies considerably. The majority of systems report in-hospital mortality rates; only some have the potential to link deaths to national death registers. Risk assessment is an important factor and there should be a distinction between recording pre-intervention factors and postoperative complications. A variety of risk scoring systems was identified in the review. Factors associated with accurate and complete data collection include the employment of local, dedicated personnel, simple and structured prompts to ensure that clinical input is complete, and accurate and automated data capture and transfer. CONCLUSIONS: The use of standardised, valid and reliable definitions is fundamental to the accurate measurement and monitoring of surgical adverse events. This review found inconsistency in the quality of reporting of postoperative adverse events, limiting accurate comparison of rates over time and between institutions. The duration of follow-up for individual events will vary according to their natural history and epidemiology. Although risk-adjusted aggregated rates can act as screening or warning systems for adverse events, attribution of whether events are avoidable or preventable will invariably require further investigation at the level of the individual, unit or department. CONCLUSIONS - RECOMMENDATIONS FOR RESEARCH: (1) A single, standard definition of surgical wound infection is needed so that comparisons over time and between departments and institutions are valid, accurate and useful. Surgeons and other healthcare professionals should consider adopting the 1992 Centers for Disease Control (CDC) definition for superficial incisional, deep incisional and organ/space surgical site infection for hospital monitoring programmes and surgical audits. There is a need for further methodological research into the performance of the CDC definition in the UK setting. (2) There is a need to formally assess the reliability of self-diagnosis of surgical wound infection by patients. (3) There is a need to assess formally the reliability of case ascertainment by infection control staff. (4) Work is needed to create and agree a standard, valid and reliable definition of anastomotic leak which is acceptable to surgeons. (5) A systematic review is needed of the different diagnostic tests for the diagnosis of DVT. (6) The following variables should be considered in any future DVT review: anatomical region (lower limb, upper limb, pelvis); patient presentation (symptomatic, asymptomatic); outcome of diagnostic test (successfully completed, inconclusive, technically inadequate, negative); length of follow-up; cost of test; whether or not serial screening was conducted; and recording of laboratory cut-off values for fibrinogen equivalent units. (7) A critical review is needed of the surgical risk scoring used in monitoring systems. (8) In the absence of automated linkage there is a need to explore the benefits and costs of monitoring in primary care. (9) The growing potential for automated linkage of data from different sources (including primary care, the private sector and death registers) needs to be explored as a means of improving the ascertainment of surgical complications, including death. This linkage needs to be within the terms of data protection, privacy and human rights legislation. (10) A review is needed of the extent of the use and efficiency of routine hospital data versus special collections or voluntary reporting.

Humans↗
PubMed1996

The fiberoptic intraparenchymal cerebral pressure monitor in 244 patients.

BACKGROUND: The fiberoptic intraparenchymal pressure monitor has been shown to provide reliable data in patients monitored for a short period of time. An analysis of a large population, including patients monitored for a prolonged period such as weeks, has never been performed. METHODS: We conducted a retrospective study in which we evaluated the fiberoptic intraparenchymal cerebral pressure monitor for complications and accuracy. RESULTS: The fiberoptic intraparenchymal cerebral pressure (ICP) monitor was used in 244 patients since 1988. Pathology included trauma in 180, intracerebral hemorrhage (ICH) in 19, aneurysmal subarachnoid hemorrhage in 16, arteriovenous malformations in 10, cerebral edema in 12, and tumor in 7. The mean length of monitoring was 7 days with 49 patients (20%) monitored 1-2 days, 105 (43%) monitored 3-6 days, 48 monitored for 7-10 days (20%), and 42 (17%) monitored from 10-24 days. Seventy-four patients also had ventriculostomies and there was strong correlation with the ICP monitor (p < 0.001). Complications from insertion were 2 patients (0.8%) with ICH, both with hepatic dysfunction. In the group monitored greater than 6 days, 34 patients (38%) required at least one catheter change due to upward drift of the ICP. Fiberoptic breakage requiring replacement was documented in 41 patients (16%). An insertion-site infection occurred in one case monitored for 23 days. Two infected bone flaps occurred that had a monitor placed in the flap. There were no cases of bacterial meningitis or cerebral abscess. CONCLUSIONS: The monitor is easy, safe, and reliable to use with a very low rate of infection. Coagulopathic patients may best be monitored by an alternative method.

Brain Edema↗
PubMed2004

Monitoring amiodarone's toxicities: recommendations, evidence, and clinical practice.

OBJECTIVES: We sought to develop an explicit evidence-based model of medication monitoring and to evaluate monitoring practices and adverse drug events in patients taking amiodarone at one institution. METHODS: We searched MEDLINE (1966 through 2000) for English-language publications providing specific monitoring recommendations for amiodarone. A cross-sectional retrospective chart review of 99 outpatients receiving amiodarone therapy between Jan 1, 2000, and Jan 1, 2001, at a large tertiary-care hospital was performed to assess monitoring practices. Adverse drug events were identified by use of structured implicit reviews. The main outcome measure was the proportion of patients receiving the monitoring recommended in the literature and having amiodarone-related adverse drug events. RESULTS: Forty-three articles were identified that provided specific monitoring recommendations, although no studies were found that compared the outcomes of patients managed with different monitoring regimens. Overall, 70% of the recommended monitoring criteria were satisfied, although only 9 patients (9%; 95% confidence interval [95% CI], 3%-15%) received all of the recommended monitoring. Variability in monitoring practices was identified at all stages of the monitoring model. Of the patients, 52 (52%; 95% CI, 42%-62%) received minimum baseline evaluations, 22 (22%; 95% CI, 14%-31%) underwent ongoing surveillance, 75 (75%; 95% CI, 61%-89%) had appropriate responses to abnormal surveillance results, and 71 (71%; 95% CI, 62%-80%) had timely follow-up visits. Of the patients, 8 (8%; 95% CI, 3%-13%) had 9 amiodarone-related adverse drug events, of which 3 were judged to be preventable. Interrater agreement for monitoring processes (kappa = 0.83) and adverse drug events (kappa = 0.67) was good. CONCLUSIONS: Current standards for amiodarone toxicity monitoring are based on expert opinion with limited evidence to support most recommendations. Monitoring practices appear to vary significantly, with few patients receiving all of the recommended monitoring. Some amiodarone-related adverse drug events may be preventable and patient safety might be improved with a better understanding of monitoring processes.

Adult↗
PubMed2004

The impact of monitoring on adherence and persistence with antiresorptive treatment for postmenopausal osteoporosis: a randomized controlled trial.

Long-term adherence and persistence with any therapy are very poor ( approximately 50%). Adherence to therapy is defined as the percentage of prescribed medication taken, and persistence is defined as continuing to take prescribed medication. We examined whether monitoring by nursing staff could enhance adherence and persistence with antiresorptive therapy and whether presenting information on response to therapy provided additional benefit. In addition we evaluated the impact of monitoring on treatment efficacy. Seventy-five postmenopausal women with osteopenia were randomized to 1) no monitoring, 2) nurse-monitoring, or 3) marker-monitoring. All subjects were prescribed raloxifene. At 12, 24, and 36 wk, the nursing staff reviewed subjects in the monitored (nurse-monitoring or marker-monitoring) groups using a predefined protocol. The marker-monitored group were also presented a graph of response to therapy using percentage change in urinary N-telopeptide of type I collagen (uNTX), a bone resorption marker, at each visit. Biological response to therapy at 1 yr was determined using the percent change in bone mineral density (BMD) and uNTX. Treatment adherence and persistence were assessed using electronic monitoring devices. Survival analysis showed that the monitored group increased cumulative adherence to therapy by 57% compared with no monitoring (P = 0.04). There was a trend for the monitored group to persist with therapy for 25% longer compared with no monitoring (P = 0.07). Marker measurements did not improve adherence or persistence to therapy compared with nurse-monitoring alone. Adherence at 1 yr was correlated with percent change in hip (BMD) (r = 0.28; P = 0.01) and percent change in uNTX (r = -0.36; P = 0.002). In conclusion, monitoring of patients increased adherence to therapy by 57% at 1 yr. Increased adherence to therapy increased the effectiveness of raloxifene therapy determined using surrogate end points.

Aged↗
PubMed1997

Monitoring in traumatic brain injury.

In the past several years, improvements in technology have advanced the monitoring capabilities for patients with TBI. The primary goal of monitoring the patient with TBI is to prevent secondary insults to the brain, primarily cerebral ischemia. Cerebral ischemia may occur early and without clinical correlation and portends a poor outcome. Measurement of ICP is the cornerstone of monitoring in the patient with TBI. Monitoring of ICP provides a measurement of CPP and a rough estimation of CBF. However, with alterations in pressure autoregulation, measurement of CPP does not always allow for determination of CBF. To circumvent this problem, direct measurements of CBF can be performed using clearance techniques (133Xe, N2O, Xe-CT) or invasive monitoring techniques (LDF, TDF, NIRS). Although direct and quantitative, clearance techniques do not allow for continuous monitoring. Invasive CBF monitoring techniques are new, and artifactual results can be problematic. The techniques of jugular venous saturation monitoring and TCD are well established and are powerful adjuncts to ICP monitoring. They allow the clinician to monitor cerebral oxygen extraction and blood flow velocity, respectively, for any given CPP. Use of TCD may predict posttraumatic vasospasm before clinical sequelae. Jugular venous saturation monitoring may detect clinically occult episodes of cerebral ischemia and increased oxygen extraction. Jugular venous saturation monitoring optimizes the use of hyperventilation in the treatment of intracranial hypertension. Although PET and SPECT scanning allow direct measurement of CMRO2, these techniques have limited application currently. Similarly, microdialysis is in its infancy but has demonstrated great promise for metabolic monitoring. EEG and SEP are excellent adjuncts to the monitoring arsenal and provide immediate information on current brain function. With improvements in electronic telemetry, functional monitoring by EEG or SEP may become an important part of routine monitoring in TBI.

Brain↗
PubMed2001

Peak expiratory flow rate and symptom self-monitoring of asthma initiated from community pharmacies.

OBJECTIVE: To compare the use of patient-performed peak expiratory flow (PEFR) and symptom monitoring as asthma self-management tools initiated from community pharmacies. DESIGN AND SETTING: 110 patients over 6 years of age were recruited from five private-sector community pharmacies. Patients were identified from pharmacist recall as having 'asthma'. Information on the frequency of their asthma symptoms, medication use, level of physical activity, school or work attendance and lung function was obtained using a questionnaire to classify patients as either mild, moderate or severe. Each patient was alternately assigned to either the symptom or PEFR monitoring procedure in the order they were recruited. Patients performing symptom monitoring used a visual analogue scale to assess symptoms, whereas those in the PEFR monitoring group assessed symptoms and used a pocket-size peak flow meter to measure lung function. Both self-monitoring groups were required to adhere to an individualized management plan based on guideline recommendations and to record their monitored data in a diary card for 2 months. Data from the diary cards were reviewed, collated, transcribed and analysed using the Student t and Mann-Whitney tests. OUTCOME MEASURES: The average monthly frequency of appropriate patient responses determined from their adherence to the self-management plan was used to compare the usefulness of symptom and PEFR self-monitoring. In particular, appropriate use of medication and need for medical consultation was compared. RESULTS: 21 symptom and 40 PEFR-assigned patients completed 2 months' monitoring. The average monthly frequency of appropriate responses in patients using PEFR (0.76) was significantly higher than that of patients using symptom monitoring (0.53, P < 0.006). Patients applying symptom monitoring had a higher monthly frequency (0.39) of inappropriate medication use compared to the PEFR group (0.14). Furthermore, the patients' mean daily symptom scores (2.85) were significantly lower than that estimated by the researcher (4.12, P < 0.03). For all three asthma severity groups a higher monthly average of appropriate responses was observed in patients using PEFR monitoring compared to those who used symptom monitoring. CONCLUSION: PEFR self-monitoring proved to be a more useful asthma tool than symptom self-monitoring. Patients applying symptom monitoring tend to underestimate the severity of their condition and use medication inappropriately. Active involvement of community pharmacists in facilitating and reinforcing out-patient self-monitoring would help to optimize asthma management.

Adolescent↗
PubMed1996

Cardiac event recorders yield more diagnoses and are more cost-effective than 48-hour Holter monitoring in patients with palpitations. A controlled clinical trial.

OBJECTIVE: To compare the diagnostic yield and cost-effectiveness of transtelephonic event monitors with those of Holter monitoring in patients with intermittent palpitations. DESIGN: Randomized crossover trial. SETTING: Diagnostic service of a teaching hospital and surrounding primary care practices. PATIENTS: 43 patients with previously uninvestigated palpitations who were referred for Holter monitoring. MEASUREMENTS: Patients were randomly allocated to receive an event monitor or 48-hour Holter monitor and then to receive the other device. Event monitors were used for 3 months or until two recordings were obtained while symptoms occurred. The main end point was an electrogram recorded during symptoms. The incremental cost-effectiveness of obtaining a diagnostic rhythm strip from event monitors was compared with that of Holter monitoring. RESULTS: The mean (+/- SD) patient age was 45 +/- 19 years; 37 patients (88%) were women. Event monitors were twice as likely to provide a diagnostic rhythm strip electrocardiogram during symptoms as 48-hour Holter monitoring (29 patients [67%] and 15 patients [35%], respectively; P < 0.001). Event monitors detected 8 patients (19%) with clinically important arrhythmias (6 patients with supraventricular tachycardia and 2 with atrial fibrillation or flutter), whereas the Holter monitors detected no significant arrhythmia (P < 0.005). With the event monitors, most patients transmitted an electrocardiogram recording by 6 weeks. Event monitors were dominant and therefore more cost-effective than 48-hour Holter monitoring, resulting in a cost savings of $213 for each additional diagnostic rhythm strip obtained during symptoms. CONCLUSIONS: Holter monitoring is a poor diagnostic test for intermittent palpitations. Event recorders provide better data and are more cost-effective.

Adult↗
PubMed2001

The therapeutic monitoring of antimicrobial agents.

AIMS: To review the basis and optimal use of therapeutic drug monitoring of antimicrobial agents. METHODS: Antimicrobial agents for which a reasonable case exists for therapeutic drug monitoring are reviewed under the following headings: pharmacokinetics, why monitor, therapeutic range, individualization of therapy, sampling times, methods of analysis, interpretative problems and cost-effectiveness of monitoring. RESULTS: There is a strong historical case for monitoring aminoglycosides. The recent move to once-daily dosing means that criteria for therapeutic drug monitoring need to be redefined. Vancomycin has been monitored routinely but many questions remain about the most appropriate approach to this. A case can be made for monitoring teicoplanin, flucytosine and itraconazole in certain circumstances. CONCLUSIONS: The approach to monitoring aminoglycosides is being redefined in the light of once daily dosing. It may be that less stringent monitoring is required in some circumstances but toxicity, especially ototoxicity, remains a problem with these drugs. Monitoring to avoid high AUCs (areas under the concentration-time curve) is recommended. The ideal method for monitoring vancomycin remains to be defined although a reasonable case exists for measuring trough concentrations, mainly to ensure efficacy. Teicoplanin is sometimes monitored to ensure efficacy while flucytosine may be monitored to avoid high concentrations associated with toxicity. Itraconazole has various pharmacokinetic problems and monitoring has been suggested to ensure that adequate concentrations are achieved.

Aged↗
PubMed1998

Automated electrocardiograph ST segment trending monitors: accuracy in detecting myocardial ischemia.

UNLABELLED: Continuous automated ST segment trending devices (ST trending monitors) are included in most new operating room electrocardiography (ECG) monitors to facilitate ischemia detection, but their efficacy is not well validated. Therefore, we compared their accuracy with that of Holter ECG recorders in detecting ST segment changes (both analyzed offline) in 94 patients undergoing coronary artery bypass graft surgery. Holter ECG tapes were analyzed using standard criteria for determining ECG ischemic episodes, which were compared with those measured by the ST trending monitors. Overall, 42 ischemic episodes were detected by using the Holter monitor in 30 patients. Of the 42 episodes, 38 (90%) were also detected by the ST trending monitors. Sixteen episodes of ST segment deviation were detected by the ST trending monitors, but not by the Holter. The sensitivity of the three ST trending monitors in detecting ischemia was 75%, 78%, and 60% for the Marquette (Milwaukee, WI), Hewlett Packard (Andover, MA), and Datex (Helsinki, Finland) monitors, respectively, with a specificity of 89%, 71%, and 69% relative to the Holter. Compared with the HP and Datex monitors, the Marquette monitor has the best agreement with the Holter (K 0.64). Conditions in which ST trending monitors may be inaccurate were identified and included the appearance of small R-wave amplitude, drifting baseline, and during periods of conduction abnormalities and pacing. We conclude that ST trending monitors have only moderate sensitivity and specificity (< 75% overall) in accurately detecting ECG ST segment changes compared with Holter ECG recordings. Therefore, sole reliance on ST trending monitors for the detection of myocardial ischemia may be insufficient. IMPLICATIONS: Using Holter recordings as the reference standard for detection of intraoperative ischemia, ST trending monitors were found to have overall sensitivity and specificity of 74% and 73%, respectively. Several conditions contribute to the inaccuracy of ST trend monitoring, and additional modification of their performance is necessary to achieve better agreement with the Holter analysis.

Aged↗
PubMed2001

Survey of use of ST-segment monitoring in patients with acute coronary syndromes.

BACKGROUND: Although effective for assessing ongoing myocardial ischemia, ST-segment monitoring may be underused. OBJECTIVES: To determine the proportion of cardiac units in the United States that use ST-segment monitoring, hospital and unit characteristics associated with its use, how units use such monitoring with respect to research recommendations, if units that use ST-segment monitoring find it clinically useful and easy to use, and why some units are not using this type of monitoring. METHODS: A survey on ST-segment monitoring was mailed to a random sample of 500 cardiac nurse managers and clinical nurse specialists. RESULTS: Of the final 192 respondents, 104 (54.2%) reported that they were using ST-segment monitoring. Monitor brand was the only characteristic associated with use of this monitoring (P = .03). On units that used ST-segment monitoring, patients were monitored if they had myocardial infarction (81%), unstable angina (79.6%), or possible myocardial infarction (78.6%) and after percutaneous transluminal coronary angioplasty (47.6%). Leads were chosen according to unit protocol (60.2%) and 12-lead electrocardiographic findings (48.5%); leads II (95.0%) and V1 (75.2%) were used most often. The majority of units that use ST-segment monitoring agreed that it is clinically useful (83%) and easy to use (56%). Among the units not using ST-segment monitoring, the most common reason was that physicians were not interested (27.1%). CONCLUSIONS: ST-segment monitoring is not routinely used; when it is, research recommendations are often not followed. Increased awareness is needed among cardiac nurses and physicians of the clinical usefulness and proper use of ST-segment monitoring.

Acute Disease↗
PubMed2004

Variations in glucose self-monitoring during oral hypoglycaemic therapy in primary care.

OBJECTIVE: To describe the prescription of glucose self-monitoring materials in the first 12 months after initiation of oral hypoglycaemic therapy. METHODS: Cohort study of subjects registered with UK general practices and prescribed oral hypoglycaemic drugs for the first time between January 1993 and December 1998. Analyses were adjusted for age, sex, year, prevalent coronary heart disease and clustering by practice. RESULTS: Data were analysed for 11 688 subjects registered with 262 practices. The proportion who received no prescriptions for monitoring increased from 24% in 1993 to 30% in 1998; urine glucose monitoring only decreased from 45 to 27%; while blood glucose monitoring only increased from 19 to 32%. In those under 45 years, 25% were not prescribed monitoring, increasing to 53% in those aged 85 years and over. In the same age groups, the proportion prescribed blood glucose monitoring only declined from 37 to 16%. At different general practices, the proportion of patients prescribed monitoring strips ranged from 12 to 100%. Practices with more registered diabetic patients were more likely to prescribe urine glucose monitoring only. Monitoring prescriptions varied widely between England, Scotland, Wales and Northern Ireland. Among eight English regions, the proportion prescribed blood glucose monitoring only ranged from 18 to 37%. CONCLUSIONS: Prescription of glucose monitoring varies according to patient and practice characteristics and geographical location. Monitoring patterns are changing over time. These variations may reflect uncertainty concerning the effectiveness of monitoring, and diversity of patient and professional preferences with respect to monitoring.

Adult↗
PubMed1995

[Continuous monitoring of critical patients with a newly developed pulmonary arterial catheter. A cost analysis].

The introduction of flow-directed pulmonary artery (PA) catheters has helped to improve our knowledge of cardiovascular physiology. There have been several developments of this equipment in recent years, including continuous monitoring of mixed-venous O2 saturation (SvO2) and cardiac output (CO). The high purchase price, however, is an obstacle to its use in the critically ill. The aim of the present study was to analyse the actual costs of these devices in comparison to standardly used intermittent monitoring of SvO2 and CO. METHODS. Thirty critically ill patients in a surgical intensive care unit (ICU) were prospectively studied. PA catheter monitoring was indicated by physicians who were not involved in the study. The patients were randomly allocated to one of the following groups: 1. a standard PA catheter was used, and SvO2 and CO were intermittently measured 6 times a day on a routine basis and additionally when necessary from the clinical point of view; 2. SvO2 was continuously measured using a fiberoptic PA catheter; and 3. CO was continuously monitored using a newly developed PA catheter. Costs for the catheter equipment and laboratory analyses (SvO2) were calculated and the durations of intermittent monitoring techniques were measured. Costs for the 'hardware' (monitor, blood gas analyser) were not taken into account. SvO2 was measured by the ICU staff using an ICU-owned blood gas analyser (4.78 DM/analysis) and by a central laboratory unit, which had to be paid for its analyses (30.50 DM/analysis), respectively. RESULTS. The groups were comparable with regard to their demographic data. A total of 378 intermittent measurements of SvO2 and 449 mean CO measurements (1611 single bolus CO measurements) were carried out in the patients in whom a standard PA catheter was inserted. For daily calibration, a total of 50 single SvO2 measurements were done in the group in which SvO2 was continuously monitored. A total of 27.7 h were spent for intermittent SvO2 measurements (time range of one analysis using the ICU-based blood gas analyser: 4.0 to 7.9 min); intermittent CO monitoring took a total of 14.2 h (time range of one mean CO measurement: 1.6 to 3.0 min). When blood gases were analysed by a central laboratory unit, costs for intermittent SvO2 were tremendously higher than when monitored continuously. CONCLUSION. Monitoring devices that provide us with continuous information on the patient's state may have advantages in the management of the critically ill. Whether the patient's 'outcome' can be improved by monitoring SvO2 and CO continuously was not addressed by the present study. Instead, this study focused on the question of whether these devices are more cost-intensive than standard PA catheter monitoring systems. Costs for laboratory analyses can blunt the advantage of lower costs for the standard PA catheter. Intermittent (standard) monitoring of SvO2 and CO was significantly more time-consuming than the continuous methods. It can be summarised that although purchase costs for the more advanced PA catheters are higher than for standard PA catheters, the use of these continuous monitoring devices in the critically ill can be justified from a financial point of view.

Cardiac Output↗
PubMed1998

Clinical trial of an ex vivo arterial blood gas monitor.

PURPOSE: The purpose of this study was to test the performance of a patient attached, on demand ex vivo arterial blood gas (ABG) monitor, and to compare the frequency of ABG analysis using the monitor, where the monitor was operated by intensive care unit (ICU) staff on shock trauma and neurosurgical intensive care patients for < or = 6 days, with standard clinical laboratory analysis. MATERIALS AND METHODS: The ABG monitor (SensiCath; Optical Sensors Inc., Minneapolis, MN) incorporates fiber optic pH, PCO2, PO2, and thermistor temperature sensors in a 0.3-mL sensor chamber that attaches in line with the patient's arterial pressure tubing and connects via a fiberoptic cable to a bedside instrument. The monitor and standard clinical laboratory performance were compared following an institutionally approved protocol. Adult ICU patients (n = 30) were studied for whom an arterial cannula was required, the expected ICU stay was > 72 hours, > or = 2 ABG analyses/day were anticipated, and informed consent had been obtained. Paired comparison ABG analyses and quality assurance checks were performed daily. The frequency of ABG analyses in this study, for which monitor values were used for clinical decision making, was compared with the frequency previously reported for the same ICUs, for which the monitor and laboratory results were compared but only the latter were used for clinical decision making. RESULTS: Five hundred ABG analyses, 436 over the first 72 hours, were obtained using the monitor for patient management over 3,248 patient hours (85 +/- 47 hours/patient). Monitor-laboratory comparison ABG analyses (n = 258) indicated stable performance over 6 days: For pH, the range of laboratory measurements was 7.200 to 7.540, accuracy (mean difference between monitor and laboratory measurement) was +0.013, and precision (standard deviation of difference between monitor and laboratory measurements) was +/-0.031. For PCO2, range: 18 to 78.5, accuracy: -0.8, precision: +/-3.4 mm Hg. For PO2, range: 41.0 to 344.0, accuracy: +2.3, precision: +/-12.8 mm Hg. The frequency of ABG analyses obtained using the monitor (ie, 15.0 +/- 11.6 ABGs/patient/72 hours) was significantly greater than that using the clinical laboratory (ie, 8.8 +/- 4.2 ABGs/patient/72 hours) (P = .01). CONCLUSION: The ABG monitor provides performance comparable to standard clinical laboratory analysis for < or = 6 days (< or = 144 hours), consistent with ICU arterial cannula changeout schedules. More frequent ABG analyses are obtained by critical care practitioners using the monitor compared with the clinical laboratory system, suggesting that clinical decision making based on ABG data may be limited by the frequency of ABG analysis.

Adult↗
PubMed1999

The therapeutic monitoring of antimicrobial agents.

AIMS: To review the basis and optimal use of therapeutic drug monitoring of antimicrobial agents. METHODS: Antimicrobial agents for which a reasonable case exists for therapeutic drug monitoring were reviewed under the following headings: pharmacokinetics, why monitor, therapeutic range, individualisation of therapy, sampling times, methods of analysis, interpretative problems and cost-effectiveness of monitoring. RESULTS: There is a strong historical case for monitoring aminoglycosides. The recent move to once-daily dosing means that criteria for therapeutic drug monitoring need to be redefined. Vancomycin has been monitored routinely but many questions remain about the most appropriate approach to this. A case can be made for monitoring teicoplanin, flucytosine and itraconazole in certain circumstances. CONCLUSIONS: The approach to monitoring aminoglycosides needs to be redefined in the light of once-daily dosing. It is premature to suggest that less stringent monitoring is necessary as toxicity remains a problem with these drugs. The ideal method of monitoring vancomycin remains to be defined although a reasonable case exists for measuring trough concentrations, mainly to ensure efficacy. Teicoplanin is monitored occasionally to ensure efficacy while flucytosine is monitored occasionally to avoid high concentrations associated with toxicity. Itraconazole has various pharmacokinetic problems and monitoring has been suggested to ensure that adequate concentrations are achieved.

Aminoglycosides↗
PubMedDate not supplied

A simulation-based evaluation of nine oscillometric blood pressure monitors for self-measurement.

OBJECTIVE: To evaluate the performance of nine self-measurement oscillometric blood pressure monitors using a simulator. METHODS: For each monitor, simulation data from 48 sets of simulated waveforms with four simulations for each set were used for analysis. The waveforms represent a wide range of blood pressure. The monitor-simulator blood pressure differences were analyzed according to the 1992 Association for the Advancement of Medical Instrumentation (AAMI) and 1993 British Hypertension Society (BHS) protocols, except that corrections were made to take into account simulation variability. One-way analysis of variance was used to compare the differences for various combinations of monitors. The monitors' heart rate readings were compared with the rated accuracy. RESULTS: First, the mean blood pressure differences in general vary from monitor to monitor, the absolute mean differences ranging from 1.2 to 18.2mmHg. This can be partly explained by the likely use of different blood pressure determination criteria. Second, the Omron HEM-711 and HEM-712C gave about the same mean difference for systolic pressure and for diastolic pressure, suggesting that the two monitors may be using the same or approximately the same set of determination criteria. Third, the quantitative assessments for some of the monitors, for systolic or diastolic pressure or both, satisfy the clinical-use accuracy criteria of the AAMI or BHS protocol or both. These assessments alone cannot, however, be used to conclude whether or not any of the monitors fulfils the accuracy requirements of either protocol. Fourth, the corrected standard deviations of the differences range from 1.5 to 16.6mmHg, most of them being substantially less than the 8mmHg limit stipulated in the AAMI protocol. The different standard deviations suggest a varying robustness of the signal-processing methods used by the monitors. Fifth, for 7 out of the 9 monitors, more than 94% of the heart rate readings fall within +/-5% of their reference readings. CONCLUSIONS: The nine monitors in general performed differently with respect to the simulator. The results cannot be used fully to reflect the monitors' performance on human subjects because they were not based on clinical evaluation. Studies that lead to a more realistic simulation of oscillometric blood pressure are needed. Protocols integrating both clinical and simulation-based evaluations need to be developed.

Analysis of Variance↗
PubMed2005

Laboratory monitoring of drugs at initiation of therapy in ambulatory care.

BACKGROUND AND OBJECTIVES: Product labeling and published guidelines reflect the importance of monitoring laboratory parameters for drugs with a risk of organ system toxicity or electrolyte imbalance. Limited information exists about adherence to laboratory monitoring recommendations. The objective of this study was to describe laboratory monitoring among ambulatory patients dispensed medications for which laboratory testing is recommended at therapy initiation. DESIGN AND SUBJECTS: We conducted a retrospective cross-sectional analysis of patients in 10 geographically distributed health maintenance organizations who were newly prescribed medications with recommended laboratory test monitoring. The main outcome measure was the proportion of initial drug dispensing without recommended baseline laboratory monitoring for 35 newly initiated drugs or drug classes. RESULTS: One hundred seven thousand, seven hundred sixty-three of 279,354 (39%) initial drug dispensings occurred without recommended laboratory monitoring. Patients without monitoring were younger than patients who had monitoring (median 57 vs 61 years, P<.001). Thirty-two percent of dispensings where a serum creatinine was indicated did not have it evaluated (range across drugs, 12% to 61%); 39% did not have liver function testing (range 10% to 75%); 32% did not have hematologic monitoring (range 9% to 51%); and 34% did not have electrolyte monitoring (range 20% to 62%) (P<.001). CONCLUSIONS: Substantial opportunity exists to improve laboratory monitoring of drugs for which such monitoring is recommended. This study emphasizes the need for research to identify the clinical implications of not conducting recommended laboratory monitoring, existing barriers to monitoring, and methods to improve practice.

Ambulatory Care↗
PubMed2006

The other side of clinical trial monitoring; assuring data quality and procedural adherence.

BACKGROUND: Data monitoring can mean different things. It can mean statistical methodologies for clinical trial monitoring, interim data analysis, monitoring for quality control or assurance or safety reporting to regulatory agencies. PURPOSE: The various facets of data monitoring will be discussed and reviewed from primarily an industry perspective. METHODS: By careful attention to the design and conduct of a clinical trial, the expense of monitoring can be markedly reduced. Careful attention should be given to the qualifications of investigators in the selection of clinical sites and central facilities. Site personnel must be adequately trained. The sponsor should utilize appropriately qualified individuals to supervise the overall conduct of the trial. The monitor should visit the investigator at the site of the investigation frequently enough to ensure acceptable quality. The monitor is responsible for inspecting the case report forms at regular intervals. Quality control should be applied to each stage of data handling to ensure that all data are reliable and have been processed correctly. The auditor will assess whether the site is being monitored in accordance with the monitoring plan. The determination of the extent and nature of monitoring should be based on considerations such as the objective, design and complexity of the trial. Statistical sampling may be an acceptable method for selecting the data to be verified. The monitor should ensure that adverse events are reported. Study data will be monitored on an ongoing basis to ensure patient safety. The sponsor may utilize a Data Monitoring Committee to protect the validity of a trial. CONCLUSIONS: Discussions between industry, academia and regulatory groups regarding the optimal extent and methods for monitoring of clinical trials are encouraged.

Adverse Drug Reaction Reporting Systems↗
PubMed1993

Duration of intracranial pressure monitoring does not predict daily risk of infectious complications.

A group of 205 patients (115 children and 90 adults) with a total of 212 intracranial pressure (ICP) monitors were retrospectively studied with attention to daily cerebrospinal fluid cultures, duration of monitoring, associated cranial injuries, and hospital site of the ICP monitor (intensive care unit or operating room). Only closed ICP monitoring systems without irrigation or compliance testing were used, and all patients received antibiotics as prophylaxis throughout the monitoring period. There were no complications associated with monitor placement. Incidence histograms and regression analysis were used to determine the daily risk of subsequent infections, in addition to evaluating the cumulative risk of infection, as has been previously described in the literature. No relation between the duration of ICP monitoring and the rate of daily infection through the period of maximal monitoring (1-2 weeks) was found in this series. The overall incidence of infection was 7.1% with a median duration of monitoring of 7.2 days. The age of the patient (adult vs. child), site of ICP monitor placement, and nature of the underlying disease (trauma vs. nontrauma) had no significant effect on the development of monitor-related infections in our study. These data indicate that the decision to continue ICP monitoring can be based solely on the clinical necessity for further monitoring rather than on concerns for monitor removal to prevent infection.

Adult↗