Anesthetic error. Part 2 (review)

“To err is human; to err repeatedly in healthcare is foolish — and perhaps even criminal”
A.A. Ryan, 2019

Introduction

In 1978, D.B. Cooper and colleagues published the results of a study emphasizing that human error was more common than pure equipment failure in preventable incidents. This marked the first time such errors were systematically highlighted in the anesthesia literature. Retrospective studies revealed that approximately 82% of incidents were unintentional human errors, such as changing syringes, inadvertent changes in gas flow, or unfamiliarity with clinical situations or equipment. Although inadequate communication, distractions and haste were analysed, the focus was made on perioperative medication errors [1–3].

Evidence of information retrieval

Studies were included for review if they met the following criteria: 1) published in Ukrainian or English, 2) addressed medical errors (MEs), 3) reported on the epidemiology and complications of anesthetic medication errors (AMEs), 4) described the causes and consequences of medication errors, 5) employed an observational study design (cross-sectional or cohort). A retrospective information search was conducted using a spatial-vector model of a descriptor-based classification system, which was further supplemented by manual searching of scientific publications.

Scientific literature was retrieved using the search engines Scopus, CrossRef, Google Scholar, and PubMed, supplemented by manual searches of referenced articles. The search terms included: ME, AME, and medication error. A total of 64 relevant scientific sources were analyzed, of which 91% were published within the last 10 years, and 67% within the last 5 years.

AME

Medication errors during anesthesia were first documented in 1948. The analysis results were supported by the Medical Research and Development Board, the Office of the Surgeon General, and the British Army Medical Department, and were submitted for publication in November 1953 [4].

During their career, an anesthesiologist may administer up to half a million different medications, making the risk of a critical error very real. In modern anesthesia practice, medication errors have been identified as the leading cause of anesthesia-related cardiac arrest in highly developed countries — surpassing respiratory events, which had previously been the dominant cause of anesthetic mortality [5].

A medication error is defined as any preventable event that may cause or lead to inappropriate medication use or patient harm. These events may be related to professional practice, prescribing and administration systems, procedures, order communication, labelling, packaging, and nomenclature, as well as medication storage, dosing, distribution, administration, education, monitoring, and usage [6–8]. Medication errors account for 28% of all MEs and are estimated to be the third leading cause of death in the United States [9]. In China, the reported incidence of treatment-related medication errors is approximately 0.73% [10].

The World Health Organization’s Global Patient Safety Challenge has identified medication safety as a pressing global issue. A medication-related incident is defined as ‘any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of a healthcare professional, patient, or consumer’. The Institute of Medicine (IOM) in the United States defines an error as ‘the failure of a planned action to be completed as intended or the use of a wrong plan to achieve an aim’ [11].

Anesthesiologists and nurse anesthetists are among the few healthcare professionals who independently prescribe, dispense, and administer medications without external oversight — assuming full responsibility for their actions. An analysis of over 8,000 reports of AMEs from district hospitals found that most incidents stemmed from failure to follow routine checks of both drugs and equipment. The majority of medication errors in anesthesia are entirely or partially attributable to human error, which is intrinsic to human psychology and behavior. As such, AMEs can be reduced — but not entirely eliminated [2, 3].

Most anesthesiologists report having encountered at least one medication error during their careers; among Canadian anesthesiologists, 85% experienced or nearly experienced an AME at least once [12].

Multiple factors contribute to medication errors during anesthesia, including the experience of the anesthesiologist and the severity of comorbid conditions. Human error accounts for approximately 66% of AMEs [13]. Contributing factors include: fatigue (53.5%), distraction (16.7%), haste, stress, and production pressure (12.5%), incorrect reading of vial or ampoule labels (12.5–23.9%), unexpected or unfamiliar drugs, vials, or ampoules (5.6%), inadequate pharmacological knowledge (5.6%), improper drug storage (5.6%) and poor communication (2.8%) [14–18].

Medication errors most commonly occur during the induction and maintenance phases of anesthesia. They are influenced by various factors, such as: the experience of anesthesia personnel, patient comorbidities, equipment involved і the type of procedure [7, 8, 19].

The causes of AMEs in operating theatres are broad — ranging from human factors to organizational issues [20]: common issues include: look-alike/sound-alike drug names, inaccurate or incomplete labelling and packaging, mislabeled syringes, syringe and ampoule swaps, unlabeled syringes and inability to correctly calculate dosages [12, 16].

Medication errors in both general and regional anesthesia occur relatively frequently, with reported rates ranging from 0.078% to 0.75% of all administered drugs. Remarkably, these figures have remained virtually unchanged over the past 15 years, and current intravenous medication safety protocols have seen insufficient updates in the last 60 years [3, 21–23]. In closed-claims audits, medication-related errors led to fatal outcomes in approximately 24% of cases, despite the availability of significantly safer modern anesthetic agents [3, 24].

Currently, the estimated frequency of AMEs ranges from 0.01% to 1.12%, or approximately 1 in every 90 to 5,000 drug administrations [17, 24, 25] and 1 in every 130 to 450 patients [26, 27].

According to a large Canadian survey, although most AMEs had minor consequences (98%), about 0.39% resulted in patient death [15]. Early data from the WebAIRS reporting system in Australia and New Zealand indicated that nearly 12% of the initial reports involved medication errors. Of these, 89% were considered preventable, and 38% resulted in moderate to severe patient harm [12, 28]. A New Zealand study found a medication error rate of 0.75% (1 in every 133 anesthetic administrations) [12, 29], while in Yemen, the rate ranged from 0.22% to 0.88% (1 in 113 to 450 patients) [19], іn Japan, the error rate was reported at 0.078% over 15 years. In South Africa, the reported rate was 0.37%. Approximately 19% of medication errors in intensive care units are life-threatening, and 42% are clinically significant enough to require life-sustaining interventions [3].

AMEs can occur due to either commission (administration of an incorrect drug or dose) or omission (failure to administer a necessary drug) [12]. The global incidence of AMEs at the point of drug administration is 0.75%, with a near-miss rate of 0.37%. The most frequent types of errors include drug substitution (20.0% to 68.4%), overdose (29.4% to 49.1%), underdose (4%), incorrect route of administration (7.6% to 8%), omission (6.5% to 35%), inappropriate drug selection (5.8%), duplication (5.4% to 17.3%), unnecessary administration (4.1%), wrong timing (3.5%), wrong patient (1.5%), incorrect side or site of regional block (1.5%), and other errors (6.5%). Most errors (58.9%) caused at least some degree of patient harm: 20.8% resulted in mild harm, 31.0% in moderate harm, and 7.1% in serious harm [3, 12, 23, 25, 28, 30, 31–34].

In terms of timing, most medication errors occurred in the morning (32.7%) and during the maintenance phase of anesthesia (49%). In 47.8% of cases, no patient harm occurred, but in 1.75% the outcome was life-threatening or resulted in irreversible damage. Wrong drug administration errors were not associated with the time of day or shift, though only one-third of incidents occurred during night shifts. Immediate recognition of the error occurred in 87.3% of cases. The most frequently reported contributing factors were distraction, fatigue (64.9%), and misreading of labels, ampoules, or syringes (54.4%) [12, 26, 31, 32, 35].

The majority of medication errors (63%) involved intravenous boluses, followed by infusions (20%) and inhalational agents (15%). This study remains one of the few that used a clearly defined denominator in error rate estimation [24].

The frequency of unexpected critical events during a­nesthetic management of surgical procedures in Ukraine was comparable to that in European medical centers, with the exception of drug administration errors. In Ukraine, the reported rate of such errors was 1.1%, which exceeds the average across European countries [20].

In large anesthesia complication databases, medication errors account for approximately 10% of all reports, with 1.6% considered life-threatening [36]. Among all medication errors, ampoule substitution accounted for 33%, and wrong drug selection for 17% [23].

Almost 40% of all errors resulted from incorrect identification of ampoules or vials [3, 23]. Currently, there is no standardized color-coding system for drug vial caps. Different manufacturers may use different colors for the same drug or concentration, which can cause confusion if suppliers and staff are not sufficiently vigilant [37]. Common contributing factors included look-alike/sound-alike drugs (27.5%), improper storage of similar medications in close proximity (16.5%), workplace haste (16.5%), involvement of multiple anesthesiologists in a single procedure (13.4%), insufficient experience (16%), failure to double-check drugs before administration (13.4%), distraction (12.6%), and over-reliance on support staff [12, 26, 28].

Wrong administration of a different anesthetic agent instead of the intended one predominantly involves the most commonly used drugs (31.6–37%) [25]. Induction agents such as sodium thiopental, ketamine, depolarizing and non-depolarizing muscle relaxants, narcotic and sedative agents, anticholinergics, and local anesthetics were administered incorrectly due to misidentification, wrong labelling, syringe swaps, or confusion and haste. However, most of these errors did not cause serious patient harm [2, 7, 11, 23]. Quantifiable patient harm was documented in 1.6% of cases [13]. The vast majority (84.4%) of life-threatening AMEs involved high-alert medications [24].

Unexpected changings syringes or improper syringe identification were the most frequent causes of fatal AMEs (42%) [23, 29, 38], with 67–71% involving muscle relaxants, opioids, sedatives, or vasopressors [13, 17, 25, 30, 39].

Error rates by drug class are as follows: muscle relaxants — 22.9–32.8%, opioids — 13.2–20%, antibiotics — 17.1%, inhalational agents — 11.4%, vasopressors — 10.3% local anesthetics — 5.8–8.6%, non-opioid analgesics — 8.6%, anticholinergics — 5.7%, induction agents — 2.9%, sedatives/hypnotics — 11% [13, 17, 25].

The drugs most often implicated in AMEs were succinylcholine, adrenaline, atracurium, fentanyl, pethidine, midazolam, phenylephrine, and bupivacaine [13, 17, 19, 25].

In pediatric anesthesia, the top five harmful drugs due to errors were morphine, potassium chloride, insulin, fentanyl, and salbutamol [36].

Common examples of drug substitution errors include thiopental instead of antibiotics and succinylcholine instead of fentanyl or oxytocin [3]. In the category ‘syringe or drug preparation errors from other or unknown causes’, the most frequent errors were administering succinylcholine or a non-depolarizing neuromuscular blocker instead of neostigmine, midazolam, opioids, atropine, metoclopramide, or oxytocin, resulting in moderate to severe harm [17, 28]. In contrast, midazolam was repeatedly administered instead of non-depolarizing neuromuscular blockers with minor consequences [17].

Some errors were classified as potentially causing serious hemodynamic or neurological damage — for example, adrenaline administered instead of oxytocin, which in some cases led to cardiac arrest [19]. Sympathomimetics, opioids, antibiotics, and NSAIDs were mistakenly substituted for intended local anesthetics during epidural anesthesia; and one case reported substitution of one local anesthetic for another during spinal anesthesia [28, 40].

The most common drugs associated with ampoule labelling errors were similar to those caused by accidental syringe swapping. The most common drug substitutions (intended/actual) included atropine/neostigmine, midazolam/rocuronium, fentanyl/succinylcholine, pancuronium/succinylcholine, succinylcholine/pancuronium, and metaraminol/naloxone. Steroids (dexamethasone) and vasoactive drugs (phenylephrine) accounted for 46.2% of substitution errors [14, 17].

Accurate dosing is critical in anesthetic drug administration [41]. Incorrect dosage occurred in 17–29.4% of all medication errors, including instances where anesthetic administration was unnecessary (2.1%) [3, 16, 17, 24, 25, 28]. Overdosing was most commonly associated with opioids (33.8%), sympathomimetics (9.6%), local anesthetics (8.8%), and insulin (8%) [28].

Overdoses often occurred because the entire vial was administered at once (24.4%) [17] duplications or dosing errors happened, particularly with opioids or paracetamol in children [3]. Sedatives and opioids were involved in 47.4% of dosing errors [14].

Of all anesthesia-related deaths in the USA between 1999 and 2005, 46.6% were caused by anesthetic overdose [33, 42]. There are reports of fatal overdoses involving benzodiazepines, methohexital, thiopental sodium, and nitroglycerin [43]. Most cases resulted in irreversible damage. Failure to monitor after opioid administration was the most common medication error [44]. There are also reports of fatal overdoses of mepivacaine and other local anesthetics during intrathecal administration [43].

Three leading causes of overdose included misinterpretation or bias in dosage estimation (53%), incorrect use of infusion pumps (21%), and preparation errors (5%). Over the past 15 years, the frequency of dosing errors has remained largely unchanged [23, 43].

A route error is an AME occurring when the correct drug is administered via the wrong route (7.6% of AMEs), involving various combinations of intended and actual administration [16, 17].

Technical AMEs include:

• Misplacement of an intravenous (IV) catheter in subcutaneous tissue (29.5%).
• Unintentional intra-arterial injection (15.8%).
• Unintentional IV injection during epidural anesthesia (15.8%).
• Unintentional IV injection during peripheral nerve blocks (13.5%).
• Unintentional intrathecal injection during epidural anesthesia (14.3%).
• Wrong-side regional block (7.9%).
• Tourniquet failure during Bier block (1.6%).
• Central venous catheter misplaced into the pleural cavity (0.8%).
• IV administration of drugs intended for epidural use (0.8%) [17, 45–49].

Most frequently, medications intended for intravenous use were administered via other routes, or drugs intended for epidural administration were mistakenly given intravenously or intrathecally. Cases have been reported of drugs for regional anesthesia administered intra-arterially and even nasal formulations administered intravenously [24, 28]. A further 5.8% of reports involved epidural infusions; one due to incorrect dosage, the rest due to unattended infusion systems (1.9%) [14].

Only 7% of respondents reported neuraxial administration errors involving 10 different cardiovascular drugs in patients aged 1 to 81 years. Among these, 51.5% were related to the epidural route. Drugs involved included digoxin (34.6%), ephedrine (23.1%), metaraminol (15.4%), labetalol (15.4%), and dopamine (11.5%). Intrathecal administration of digoxin (instead of bupivacaine) resulted in paraplegia and encephalopathy in 30.8% of cases [31, 32, 49, 50].

The most common route-related technical errors (14%) were unintentional intra-arterial injection, subcutaneous injection via misplaced IV catheter, and unintentional IV injection during epidural or peripheral nerve block procedures [17, 46].

The most frequent equipment-related medication error was improper use of IV access (including central lines). Reflux errors were also common, where the intended medication was delivered to the wrong part of the IV system rather than to the patient. Arterial lines were sometimes mistakenly used for IV drug administration. Best practices include clearly labelling and identifying IV lines and confirming line integrity before drug administration. The use of anti-reflux valves in total intravenous anesthesia systems is recommended. Malfunctions with IV infusion pumps were heterogeneous, but interface usability issues were the leading cause. Standardization at the industry level could help reduce such errors [17].

Reports also include administration through non-sealed IV, epidural, or intra-arterial cannulas, and malpositioned central venous catheters resulting in intrapleural infusion of norepinephrine. A contributing factor in many route errors was concealment of IV and epidural lines beneath surgical drapes or linen [28].

The American Society of Anesthesiologists’ closed claims analysis identified serious complications from malpositioned central venous catheters. Use of ultrasound guidance during central venous catheterization, according to ‘Safety Rule 101’, significantly reduces the risk of complications due to visualization of anatomical structures [51, 52].

To prevent misconnections in medication delivery systems, the use of unique connectors for anesthesia catheters and infusion components is advisable [53].

There were also reports of wrong-patient medication errors. In five such incidents, drugs intended for a previous patient were not properly discarded and were mistakenly administered to the next [28].

Prescription errors included administering drugs to patients with known allergies (9% of prescribing errors), though such mistakes accounted for less than 1% of all AMEs — approximately 1 in 1.4 million patients annually. This aligns with data from the UK national medication error database. Incorrect drug selection related to patient comorbidities accounted for 34.6% of anesthetic prescribing errors [17, 36].

In China, the most common AME categories were omissions, incorrect dosages, and drug substitutions, together accounting for over 65% of all reported errors [3]. Omission errors occurred when a drug was mistakenly left out of the anesthetic plan (16.3%) [17].

In 2.1% of cases, drugs were administered too rapidly. In intensive care settings, inappropriate infusion rates were observed in 40% of incidents [54].

Reported incidents also included administration of expired medications (2.1%), reuse of syringes from a previous patient (2.1%), and other procedural breaches [17].

Common preparation errors involved incorrect dilution of morphine—either under- or overdilution—and administration of sterile water alone instead of a properly prepared vecuronium solution [17].

Succinylcholine is associated with numerous adverse effects, including life-threatening hyperkalemia, especially when administered rapidly [17, 55].

Residual anesthetic drugs remaining in intravenous infusion lines may cause fatal outcomes, such as respiratory arrest followed by circulatory collapse due to residual neuromuscular blockers [3].

Cases have been reported where mannitol solution was mistakenly used instead of normal saline to flush an arterial line containing heparin, leading to inactivation of the anticoagulant [17].

The main causes of medication errors are insufficient knowledge about anesthetic drug actions, distractions, involvement of multiple personnel in drug administration, and poor communication [12, 28].

Due to the multitasking nature of anesthesia practice, clinicians may misidentify drugs while performing other tasks [15]. Similar-looking vials and ampoules also contribute to errors; therefore, anesthesiologists must maintain vigilance throughout anesthesia administration [39].

Modern healthcare systems are developing strategies aimed at reducing AMEs [26]. The Airway Management Society and the Association of Anesthetists of Great Britain recommend that manufacturers improve and standardize ampoule design and packaging using approaches such as larger font size for drug names and smaller font for manufacturer logos, preference for generic over brand names, and consideration of color standardization and differentiation [56].

Medication safety is likely improved by routine use of prefilled syringes and infusion pumps [56]. Vials should be single-use only [37]. Administration of drugs intended for a previous patient can be effectively eliminated by strict procedural protocols for drug disposal after use [28].

Barcode scanning systems are the most effective intervention, reducing AMEs from 2.26 to 0.17 per 10,000 episodes in emergency and intensive care settings [41, 57]. The barcode label is scanned prior to drug administration [26, 30, 43].

Color-coded syringe labeling is another effective strategy, reducing errors by 64% [15, 39, 41, 57]. However, nearly all participants in one study (97.11%) reported no availability of color-coded syringes in their hospitals [15]. Some researchers have expressed concern that reliance on color coding might increase errors if clinicians neglect to read labels. Labels should be applied immediately after syringe filling; clinicians who labeled syringes before filling made more errors (p=0.036). Less experienced clinicians also committed more errors (p=0.015) [37].

Double-checking reduces medication errors from 2.98 to 2.12 per 1,000 drug administrations [15, 39, 41, 57].

Anesthesiologists who did not consistently double-identify drugs before administration had a 3.5-fold higher risk of medication complications compared to those who always double-checked. Additionally, anesthetists administering drugs prepared by others were approximately five times more likely to commit errors than those preparing drugs themselves [15].

The identification system in the operating room includes individualized drug trays, prefilled syringes of commonly used medications, color-coded labels, barcode scanners combined with auditory and visual verification [26, 43]. Standardized placement of drug trays and workspace organization aids rapid drug selection in emergencies and reduces ampoule substitution errors [30]. Electronic systems significantly reduce MEs and related mortality, improving service efficiency and patient safety [57].

Automated anesthesia carts significantly decrease drug identification errors compared to manual carts (р<0.01) [58]. Implementation of automated dispensing cabinets (ADCs) in intensive care units reduced medication prescribing and dispensing errors from 0.046% to 0.026%, i.e., from 3.87 to ~ 0 per 100,000 episodes [59].

At first glance, automated systems appear reliable tools for preventing human errors and improving patient care. Computers do not tire or become distracted, read information almost instantly, and closed drug delivery systems may be safer and more accurate than manual administration [60]. Computerized systems display allergy alerts if such data is in the patient record, or reminders for drug dilution when vasoactive agents are loaded [30].

Automated medical technologies are increasingly integral to anesthesia practice, enhancing patient safety but potentially introducing new workflow challenges and unexpected adverse events that must be addressed before clinical implementation. Any medical device can fail unexpectedly, requiring rapid clinician intervention to avoid harm [60]. Although smart pumps were introduced for patient safety, they cannot prevent all types of drug administration errors and may create new issues [61]. Novel technologies may also distract operators and lead to unforeseen human errors [21, 24].

Product identification discrepancies related to automated pumps can cause errors; fatal incidents have been reported due to infusion pump use without proper education and training [51, 62]. That is why ADCs are recommended to exclude muscle relaxants [63]. In 2017, an anesthetic administration error associated with an ADC led to patient death and widespread publicity, culminating in criminal prosecution of the healthcare worker concluded in 2022 [63, 64].

Multimodal interventions and enhanced labeling mechanisms effectively reduce anesthetic errors [22]. Thus, systems should be developed to minimize drug identification errors through approaches such as reviewing ampoule and vial labeling standards and advanced electronic/digital double-check mechanisms [3].

The motto for all anesthesiologists should be: ‘Eternal vigilance is the price of safety’ [39].

Other groups of anesthetic errors will be discussed in Part 3 of this review.

References

Надійшла до редакції/Received: 26.10.2025
Прийнято до друку/Accepted: 11.11.2025