INTRODUCTION

Preventable adverse drug events involving intravenous medications (preventable IV-ADEs: injuries owing to intravenous medication errors) occur frequently in intensive care units (ICUs).1,2 Many errors occur during medication administration, and calculating infusion rates and programming pumps are high-risk steps.2,3 Programmable infusion pumps with safety software (“smart pumps”) were designed to intercept such errors by displaying alerts if continuous-infusion dosages exceed hospital-defined ranges or, for one pump, if duplicate infusions are administered.4

Three studies indicate that the reprogramming of smart pumps in response to alerts occurs frequently.5–7 However, because most medication errors happen not to cause harm,2,8 the ability of smart pumps to reduce IV-ADEs also warrants investigation. One study evaluated whether smart pumps prevent IV-ADEs and found no significant decrease.8 No studies have assessed how often preventable IV-ADEs actually match smart-pump safety features or whether expanding pump capabilities might prevent additional types of IV-ADEs.

In this study, we sought to determine how frequently preventable IV-ADEs match one smart pump’s features and to identify additional smart-pump capabilities. Our ultimate objective was to compare preventable IV-ADE incidence rates between smart pumps and conventional pumps.

METHODS

Overview

We used quantitative and qualitative methods to examine preventable IV-ADEs in adult ICUs before and after 2 hospitals replaced conventional pumps with smart pumps.

Setting and Subjects

With assistance from the study sponsor (Cardinal Health, San Diego, CA, USA), we selected 2 hospitals that had implemented their smart pumps in 2003 (Alaris version 5): an academic hospital in the northeast and a nonacademic hospital in the west. We examined 20,000 bed-days of care in surgical, trauma/burn, and medical ICUs, half during conventional-pump study periods and half during smart-pump periods. We obtained Institutional Review Board approvals; informed consent was not required.

Smart-Pump Features

A programmable unit within the pump controlled up to 4 attached infusion devices and recorded (“logged”) programming errors, alerts, reprogramming events, and overrides. Before implementation, study hospitals developed software libraries for drugs given by continuous infusion; bolus dosing was not addressed. The manufacturer suggested dosing limits then hospitals made modifications. ICU libraries included over 50 drugs.

Nurses could program the pumps as if they were conventional or use the library’s safety features. Once in the library, nurses selected a drug and standard concentration then entered the dose. For weight-based dosing, nurses entered patient weights and doses, then the software calculated flow rates. When doses exceeded library limits or duplicate infusions were programmed, the software provided alerts and prevented infusion until they were addressed; overrides were permitted.

Data Collection

This included abstracting medical records and rating suspected ADEs. We did not observe pump use or abstract smart-pump logs.

Critical care nurses (4–5 per hospital; uninvolved in study participants’ care) received 4-day trainings in medical-record abstraction and ADE identification (reading manuals, discussing examples, and reviewing sample records). During data collection, nurses recorded clinical and demographic data then used manual trigger-tool review (which uses key words as sentinels to identify ADEs)9 plus implicit review (professional judgment) to identify suspected ADEs and any events that infusion pumps might have caused. For each suspected ADE, they summarized relevant details of medication therapy,10 errors, and injuries. Reliability assessment involved reabstracting 100 records.

Four board-certified Internal Medicine physicians (unaffiliated with study hospitals) rated suspected ADEs. Two reviewed each electronic summary individually then met to reach consensus, rating: whether an ADE occurred,2 drugs involved, routes/modes of administration,2 preventability,11 errors involved,2 and whether errors matched smart-pump functions at each hospital (i.e., whether continuous-infusion doses were outside library limits or present in multiple infusions). Reliability assessment involved randomly selecting 50 suspected ADEs.

Quantitative Analysis

We used SAS version 9.1.3. First, we examined administration routes/modes, drugs, stages in delivery, and errors involved in preventable IV-ADEs overall. Second, we calculated incidence rates (preventable IV-ADEs per 1,000 patient-days in ICU) for preventable IV-ADEs matching smart-pump functions in each study period. Third, we compared total preventable IV-ADEs incidence rates between conventional-pump and smart-pump periods using Poisson regression models that included multiple demographic and clinical variables. We had 80% power (alpha = 0.05) to detect a 46% change. Finally, we determined intracluster correlations for nurse and physician ratings.12

Qualitative Analysis

For events matching smart-pump features, we summarized errors involved. For other events, we summarized examples of common errors and explored additional smart-pump capabilities.

RESULTS

Among 4,604 patients with 20,559 bed-days in ICU, we identified 100 preventable IV-ADEs (4.86 per 1,000 patient-days). Half of preventable IV-ADEs involved continuous infusions and 40% boluses. Morphine, insulin, fentanyl, and propofol represented 44% of all drugs involved. Half of errors occurred during ordering, 14% during administration, and 35% during monitoring. Failure to intervene, failure to monitor (37% combining subtypes, not shown), and overdose were common errors (Table 1). Two preventable IV-ADEs in each study period (4%, 0.19 per 1,000 patient-days) matched smart-pump functions at each hospital (Table 2). No pumps caused any injuries.

Table 1 Types of IV Medication Errors Causing Preventable IV-ADEs in Both Study Periods Combined
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Table 2 Qualitative Analysis of Errors Causing Preventable IV-ADEs
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As noted in the Introduction, our ultimate objective was to compare total preventable IV-ADEs incidence rates between conventional-pump and smart-pump periods. However, given that few preventable IV-ADEs matched smart-pump features, statistical power was severely inadequate. The conventional-pump rate was 4.78 per 1,000 patient-days and the smart-pump rate was 4.95 (adjusted mean difference 0.04 per 1,000 patient-days, p = 0.96).

Event descriptions suggested that expanding smart-pump library applications, integrating pumps with vital-sign and laboratory data, integrating pumps with computerized physician order entry (CPOE), and automating medication titration might prevent additional IV-ADEs (Table 2). The intracluster correlation for nurses identifying suspected events was 0.39. Physician intracluster correlations were: for ADEs, 0.71; preventability, 0.90; and smart-pump preventability, 1.0.

DISCUSSION

Examining preventable IV-ADEs among 4,600 adult ICU patients, we found that only 4% could be intercepted by a smart pump that detects duplicate and excessive doses of continuous infusions. There were several reasons for the low rate of corresponding events: these pumps did not address boluses, the dosing ranges appeared too wide for certain patients, and monitoring problems were more common than administration ones. Nevertheless, we observed that expanding pump functions and integrating them with real-time clinical data might enable smart-pump technology to reduce other common, harmful errors.

Four evaluations of similar smart pumps came to more positive conclusions. Comparing 426 infused medications with physician orders during a 9-hour period, researchers judged 1 error to be smart-pump-preventable because it was a rate-deviation error involving a pump-programming mistake.13 Three studies examining smart-pump logs found that reprogramming events, assumed to be intercepted errors, were common.5–7

Because errors have unpredictable relationships to injuries, however, preventable IV-ADEs must also be examined; for example, 0.9% of medication errors caused ADEs in medical floor units versus 11% in cardiac ICUs.2,8 A controlled trial evaluating a similar pump did consider preventable ADEs and found no significant reduction, because of limited power and because nurses used its safety features inconsistently.8

In contrast, our analysis revealed that substantially reducing preventable IV-ADEs in ICUs would require smarter pumps. Many preventable IV-ADEs involved failures to monitor for or adequately respond to undesirable medication effects. Smart-pump technology could alert nurses to such failures by integrating infusions with CPOE, and real-time vital-sign and laboratory data. Perhaps more controversially, smart pumps could automate some titration tasks. Intensive insulin infusions seem particularly amenable to automation because complex protocols create many opportunities for error; clinical assessment is rarely required; and an automated technique for tightly controlling blood glucose, the euglycemic glucose clamp, already exists.14 Others have described closed-loop systems for titrating sedatives.15

The manufacturer of the pumps we evaluated has already expanded applications to include boluses, syringe pumps, and patient-controlled analgesia. An integrated bar-code reader has been designed to address wrong-patient and wrong-drug errors. A patient-controlled analgesia pump monitors oxygen saturation and end-tidal carbon dioxide, issuing an alert or shutting off if values deviate from hospital-defined ranges (Butterfield, personal communication, 2006).

As with any technology, new smart-pump capabilities have potential barriers to overcome. Integration with bar coding and CPOE assumes that hospitals are adopting these technologies, which may not be the case.16 Incorporating real-time vital-sign data may require nursing practice changes. Integration with laboratory data would require software development. Automating monitoring and titration tasks would reduce nurses’ opportunities to practice these skills.17 Finally, new safety technologies can introduce new errors.18 Consequently, expanding smart-pump applications will require careful development and testing.

Regarding limitations, we may have underestimated events matching smart-pump functions because we could not evaluate smart-pump logs or observe users. Nursing agreement was only fair, possibly owing to insufficient training or reabstracting too few records; other studies have not reported nurse agreement. However, we used standard methods and documented physician agreement comparable to prior studies.19 We studied 2 hospitals, 1 clinical setting, and 1 time period. Smart-pump technology is evolving rapidly and future research should include non-ICU settings, where IV-ADEs may not be detected quickly.

CONCLUSIONS

The smart pumps we evaluated are unlikely to reduce preventable IV-ADEs in ICUs because they address only 4% of them. Expanding smart-pump capabilities might prevent more IV-ADEs.