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 Table of Contents  
Year : 2022  |  Volume : 25  |  Issue : 3  |  Page : 80-85

Macrodrip infusion dose error among nurses

1 Department of Nursing, Faculty of Clinical Sciences, University of Port Harcourt, Port Harcourt, Rivers State, USA
2 Department of Nursing Sciences, College of Health Sciences, Abia State University, Uturu, Nigeria
3 Home Health Amedisys Company, Worcester, Massachusetts, USA

Date of Submission17-Jul-2020
Date of Decision31-Aug-2020
Date of Acceptance11-Sep-2020
Date of Web Publication20-Nov-2023

Correspondence Address:
Mr. Chinemerem Eleke
Department of Nursing, Faculty of Clinical Sciences, University of Port Harcourt, Port Harcourt, Rivers State
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/smj.smj_87_20

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Background: Infusions must be administered as prescribed as too fast or slow a dose could have deleterious effects. Objectives: This study examined the risk for macrodrip infusion dose error among nurses in selected tertiary hospitals in southern Nigeria. Materials and Methods: This cross-sectional study was conducted in five university teaching hospitals in 2019. To establish the drop factor of commonly available macrodrip sets, 25 macrodrip sets were randomly sourced from the hospitals' pharmacies. A sample of 291 nurses was selected using proportionate random sampling technique. Data were collected using the adult infusion dose calculation quiz. Collected data were described and analyzed at 5% level of significance. Results: About 20 (80%) of the sampled macrodrip sets revealed 20 drops/ml (gtts/ml) drop factor value displayed on the packaging. When measured experimentally, all (100%) of the macrodrip sets delivered exactly 20 gtts/ml. About 255 (87.6%) respondents calculated macrodrip infusion dose while using a wrong drop factor of 10–18 gtts/ml while an additional 12 (4.2%) could not arrive at the expected infusion dose due to formula and arithmetic anomalies. In all, 267 (91.8%) respondents demonstrated tendency for infusion dose calculation error. Nonattendance of training on infusion administration significantly increased the risk for error by 21% (P = 0.001). Conclusion: Twenty gtts/ml is the drop factor of common macrodrip sets in southern Nigeria, and nurses were prone to infusing patients at a lower dose than prescribed. Attending training on infusion therapy might remedy this malady.

Keywords: Infusion, medication error, Nurses

How to cite this article:
Eleke C, Agu IS, Ngbala-Okpabi S, Bempong-Eleke EN. Macrodrip infusion dose error among nurses. Sahel Med J 2022;25:80-5

How to cite this URL:
Eleke C, Agu IS, Ngbala-Okpabi S, Bempong-Eleke EN. Macrodrip infusion dose error among nurses. Sahel Med J [serial online] 2022 [cited 2023 Dec 6];25:80-5. Available from: https://www.smjonline.org/text.asp?2022/25/3/80/389946

  Introduction Top

Medication errors are the seventh-most common cause of death in healthcare globally.[1],[2] The highest risk of medication error occurs with intravenously administered infusions.[3] Medication error is a preventable event that could arise from unintentional misapplication of medication by a clinician.[4] Medications such as intravenous infusions are often prescribed for hospital admitted patients for fluid replacement and as a medium for medicines.[5] It is, therefore, a valuable medical intervention for patients who have inadequate oral fluid intake and excessive fluid loss.[6] It however has some risk, especially when administered in error.[7] Administration of infusions must be done as prescribed because it could be detrimental to patients if given too slow or fast.[8] In recent times, errors in the speed of infusion have grown to be the most common type of medication error.[9]

Infusion prescriptions are often not written in drops per minute speed (gtts/min).[10] The required speed of prescribed infusion is often left for the attending clinician to calculate using the formula:

.[11] This complexity can prove problematic for clinicians with little mathematical ability, especially during clinical emergencies.[12] In advanced countries, concerns over patient safety have resulted in the use of error reduction smart pumps technologies with preset drops per minute calibration for regulating infusion dose delivery.[9] In developing countries, however, the use of error reduction smart pumps is not widespread.[13],[14]

Drop factor of drip set refers to the number of drops in the drip chamber that produces exactly 1 ml of fluid into a receptacle.[11] Drop factors of 10 and 15 gtts/ml have been documented for travenol/baxter and Abbott/McGraw branded macrodrip sets, respectively, in the UK literature.[15] American literature has documented 20 gtts/ml.[16] Indian and African authors have also documented drop factor values of 15, 16, and 20 gtts/ml.[5],[17],[18] In developing countries where manufacturer labels of drip sets are not strictly monitored, discrepancies have been observed between prescribed and administered infusion rates between physicians and nurses.[2],[8] This study examined the risk of macrodrip infusion dose error among nurses in selected tertiary hospitals in southern Nigeria.

  Materials and Methods Top

Study design

A cross-sectional design was adopted for this study, which was conducted in five university teaching hospitals in the southern of Nigeria between September and December of 2019. The target population for the study included nurse clinicians practicing in the University Teaching Hospitals, amounting to an estimated 3186 individuals. Applying the Fisher (1988) sample size calculation formula:

, a final sample size of 380 was determined after 10% to cater for 10% potential nonresponse.[19],[20]


Proportionate random sampling with balloting technique was used to select consenting respondents. The criteria for inclusion in the study were willing to participate in the study, can use an electronic calculator, and physically and mentally stable enough to respond to questionnaire items. The exclusion criteria were nurses on leave and nurses in administrative or nonclinical roles in the hospitals.

In order to determine by measurement the drop factor of available macrodrip sets, 5 macrodrip sets were randomly selected from each of the five selected hospital's pharmacy (total of 25 drip sets).


Pretested and validated structured questionnaire was used to collect information on the drop factor value seen on the label of the macrodrip sets, demographic data, educational qualification, training on intravenous therapy, formula for calculation of infusion drop rate (gtts/min). A checklist was used to assess relevant skills including ability to state correct formula, substituting correctly the right drop factor into the formula, applying the correct drop factor value, arithmetic computation ability and arriving at the correct answer. Five nursing research experts from two Nigerian Universities assessed the instrument for Content Validity. Agreement between the raters regarding the instrument items was computed to be 0.83; therefore, the instrument was considered valid.[21],[22]

Data collection method

After explaining the aim of the study to the respondents, the questionnaires were submitted to the respondents to fill in their space of choice and return it to the research team within 15 min.

Data analysis

Data were statistically analyzed with the aid of the Statistical Package for the Social Sciences version 25 (IBM SPSS Inc., Chicago, IL, USA). Categorical variables were summarized with descriptive statistics (frequencies and percentages). Chi-square and relative-risk were used to compare differences between the categorical variables, and P < 5% was considered statistically significant.

Ethical consideration

Ethical approval was obtained from the Federal Medical Centre, Umuahia, Health Research and Ethics Committee (FMC/QEH/G.596/Vol. 10/417) on September 4, 2019. The study protocol was adhered to the 2013 Geneva declaration guideline. Informed consent to participate in this study was obtained from each respondent.

  Results Top

Out of a total of 380 questionnaires administered, 291 questionnaires were filled by the respondents, giving a response rate of 76.6%. The age of respondents ranged from 20 to 59 years (mean 36.7 ± 11.2 years). Most of the study participants were females (264; 90.7%) and about half of them had bachelors of nursing science degree as their highest educational qualification (151; 51.9%). Majority of the study participants had not attended any special training on intravenous administration (240; 82.5%). [Table 1] illustrates the sociodemographic profile of the respondents.
Table 1: Sociodemographic profile of the study participants (n=291)

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A total of 25 macrodrip sets of five brands sourced from the hospitals' pharmacies were examined. Most (20; 80%) of the macrodrip sets had a drop factor value of 20 gtts/ml displayed on the packaging. When the drop factors for each macrodrip set was manually counted and measured, all (25; 100%) the macrodrip sets delivered 20 drops/ml (gtts/ml). [Table 2] summarizes details and characteristics of the macrodrip sets.
Table 2: Drop factor values of common brands of macrodrip sets in South Nigeria (n=25)

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Most (267; 91.8%) of the respondents demonstrated palpable errors in infusion dose calculation. Only 81 (27.8%) of the respondents were able to state the correct infusion calculation formula, 36 (12.4%) was able to substitute drop factor in the stated formula, and 36 (11.7%) applied a drop factor value of 20 gtts/ml in the stated formula, while the majority (48.1%) of the respondents applied a drop factor value of 15 gtts/ml in their infusion dose calculation. The arithmetical error was not observed in majority (184; 63.2%) of the responses. [Table 3] summarizes the responses to infusion dose calculation.
Table 3: Infusion dose calculation ability among nurses (n=291)

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There was a significant relationship between attendance of special training updates on intravenous fluid administration and infusion dose calculation error (Fisher = 14.50, P = 0.001). Nonattendance of training intravenous fluid administration increased the risk of infusion dose calculation error by 21%. Meanwhile, there was no significant association between Educational qualification and infusion dose calculation error (P = 0.273). [Table 4] summarizes the test of hypotheses.
Table 4: Predictors of risk of infusion dose delivery error (n=291)

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  Discussion Top

This study indicates that the drop factor of the most commonly used macrodrip infusion sets in southern Nigeria is 20 gtts/ml. In other words, 20 drops into the drip chamber of the infusion set will infuse 1 ml into a patient. This finding was completely supported another Nigerian author who wrote that macrodrip sets used in Nigeria have a drop factor of 20 gtts/ml.[18] Furthermore, this finding supported Royal College of Nursing U.K who affirmed that a macrodrip drop factor of 20 gtts/ml should typically be used in infusion dose calculations involving clear fluids like dextrose water, dextrose saline, normal saline and ringer's lactate among others.[23] Meanwhile, this finding was in contrast to a macrodrip drop factor value of 15 gtts/ml documented in Nursing and Midwifery Council of Nigeria recommended textbooks used in nursing colleges within Nigeria.[15],[17] The finding also falls out of line with the macrodrip drop factor value of 16 gtts/ml documented in India.[5] This finding may be pointing toward a need for revision of textbooks used in nursing colleges in line with existing facts within the Nigerian clinical area, as this would limit the gap between theory and practice. In addition, some authors have recommended that nurses should regularly examine the drip sets used in their wards for drop factor values.[1],[15] This would help protect patients from complications, and nurses from litigation resulting from unintended under and over delivery of infusion dose.[24]

This study further revealed that about 20% of the macrodrip infusion sets in circulation within southern Nigeria had no drop factor value clearly indicated on the packaging. One may suspect a level of indifference among clinical administrators about this anomaly. Perharps, such irregularity is not considered worthy of control, probably because they are so widespread. That could explain why macrodrip sets without drop factor values clearly indicated on its packaging would be found in some university teaching hospital pharmacies. Such omission could result in 50.1% of infusion-related error as noted in a Canadian study.[12] Inaccurate rates of infusion can be disasterous to patients and clinicians are accountable for the dose of infusions they give.[6] Based on the fore mentioned, there may be need to regulate and cross check the labelling of inteavenous drip sets for drop factor by government authorities.

Varying degrees of difficulties with infusion dose calculation were observed in this study which include the inability of most (91.8%) of the respondents to arrive at a correct infusion dose amid many (63.2%) of them demonstrating good arithmetic skills. This finding was not in line with a Saudi Arabian study which found that 13.9% of nurses was prone to medication error as measured using their performance in drug calculation against a pass mark of 80%.[7] Moreso, this finding was somewhat similar to that in a study which found that 58.5% of nurses were prone to infusion dose delivery error in Pakistan.[14] Based on the premise that a larger sample size enhances external conclusion validity, the findings of the present study could be considered more valid than that documented in Pakistan.[21] Nonetheless, this finding largely supports a British study which found that 89% of registered nurses failed drug calculation test even when arithmetic was passed by 55% of them.

This study found that nonattendance of special training programs on intravenous fluid administration was significantly associated with a higher risk of infusion dose calculation error. This finding supported an Ethiopian, which proposed that enhancing the knowledge and practical skills of clinical nurses would reduce intravenous fluid administration errors. This finding further aligned with two other studies that found that nursing staff training substantially reduce the probability of intravenous infusion errors.[1],[10] Nonetheless, a significant association was not found between educational qualification and infusion dose calculation error. This would suggest that, statistically speaking, the educational qualification of clinical nurses does not significantly lower their tendency of infusion dose calculation error. This finding supported a US study which found that 75% of faculty members demonstrated error in infusion dose calculation and their error rate increased with years of faculty experience (P = 0.007). This finding further supported an article which noted that although nurses enter the professional register with an assessed level of infusion calculation competence, that competence can decrease over time to suboptimal levels. Against this backdrop, continued training to refresh the different types of drug calculations should be embarked on as often as possible to prevent the deskilling of nurses.[25]

The limitation of this study related to time maturation threat to validity as the study participants were allowed to fill the instrument at their chosen space. This may have exposed the respondents to some interaction with other colleagues while filling the instrument, hence may have contaminated the responses. Based on the identified limitations, the findings of this study must be interpreted with caution regarding generalization outside this study population.

  Conclusion Top

It is concluded that the most accurate drop factor of macrodrip infusion sets used was 20 gtts/ml. Nurses are prone to infusion calculation errors. We recommend training on infusion therapy as a remedy.


We thank all nurses who participated in this study, Dr. Daprim Ogaji (PhD, MBBS) and Dr. Goodluck Azuonwu (PhD, RN) of the Faculty of Clinical Sciences, University of Port Harcourt for their technical support towards the success of this study.

Financial support and sponsorship

A self-sponsored study.

Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Table 1], [Table 2], [Table 3], [Table 4]


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