What Is A 60-drop IV Set or Micro IV set?

Description of the micro drip IV set

A 60-drop gravity IV set or micro drip IV set refers to an infusion set that delivers 60 drops per mL. of the infused fluid. With this drip rate, it has a drop factor of 60. Manufacturers and researchers define the drop factor as the number of drops in one mL of the solution infused by medical workers using a gravity IV set. Manufacturers print the drop factor on the IV set package to guide prospective users. Macro drip IV set, on the other hand, delivers drop factors of 10, 15, or 20 drops per mL, and health workers use it to infuse general IV solutions into adults. 

As the name suggests, the micro drip IV set consists of a narrower cylindrical duct. For this reason, it generates smaller drops than those arising from the macro drip. Micro drip (mini drop) generally comes in a single size of 60 drops per mL. This drip rate implies that 60 drops of liquid make a total volume of one mL.

Primary uses of the micro drip IV set

• To deliver precise medication dose: Health workers use the micro drip IV set to infuse exact amounts of medications in tiny drops to children and infants. In another saying, health providers use a micro drip IV set to infuse IV medications that need precise administration.  
• To serve as an efficient substitute for an IV pump: Physicians and nurses administer sensitive medications using an IV pump to attain the required precision. Based on the study titled ‘Medication and volume delivery by gravity-driven micro-drip intravenous infusion, potential variations during “wide-open flow”‘ authored by Eric T. Pierce et al., the researchers found that mechanical pumps enhance the precision and safety of infused drug delivery more than the manual control of gravity-driven infusions, especially for IV vasoactive substances. However, an IV pump is not always available in a medical center or a hospital. Without an IV pump, health workers resort to using the micro drip IV set instead because it approximates the efficiency of an IV pump. Infusing nitroglycerin, dopamine, dobutamine, and nipride requires a micro drip IV set.

Advantages of the micro drip IV set

• Gravity-driven micro-drip infusion set allows control of medication dose delivery by adjusting drops per minute. Health workers, especially anesthesiologists, find operating very convenient and easy.
• Manufacturers designed the gravity-driven micro-drip infusion sets such that the number of drops per minute equals the milliliters per hour. For example, a 60 drops/minute drip rate delivers 60 mL/hour during regular operation. This relationship between volume delivery and drip rate remains constant regardless of physical factors, such as the height of the fluid bag over the patient or resistance to the flow of the IV fluid. Thus, medical workers avoid errors and confusion in administering IV fluid and medications. For these reasons, prospective and existing users of the micro-drip infusion set could easily remember the principle involved in its use.
• Using a micro drip infusion set is relatively inexpensive.
• Micro drip infusion is the best alternative to use if a patient cannot tolerate drugs by oral or any other route.
• Patients receive immediate therapeutic effects due to the rapid delivery of the medications admixed in the fluid to target sites.
• Patients need to receive drugs causing pain and irritation via the intravenous route so as not to experience them.
• Absorption of some drugs occurs via the intravenous route.
• Given intravenously, the total dose of the medications reaches the patient’s circulatory system.

Disadvantages and limitations of a micro drip infusion set

Based on the study of Pierce et al., the principle involved in using the micro drip infusion set—that 60 drops per minute will infuse 60 mL in 1-hour infusion—holds if medical workers still see the discrete drops in the drip chamber. However, suppose a nurse or physician widely opened the roller lock or clamp, designated as a “wide-open” condition. With that change, the continuous and unbreakable flow of fluid replaces the discrete and countable drops in the drip chamber. In that case, other factors will affect and dictate the delivery of medication dose and fluid volume.

Consequences of “wide-open” condition on the micro drip infusion set

• The following factors—the height of the fluid or infusate bag relative to the patient, the size of the IV catheter, and the flow of other fluids through the same IV set—will directly affect the delivery of the medication dose and fluid volume.
• With the size of the catheter unchanged, the fluid flow increased as the height of the fluid was increased.
• With the height of the fluid container unchanged, the flow increased as the catheter size increased (gauge number decreased).
• The volume delivered by the piggybacked micro-drip decreased as the carrier flow increased.
• Resistance (fluid height/flow rate) increased as catheter size decreased (gauge number increased).

Precautions in the use of micro drip infusion set

Using a micro drip infusion set assures prospective and existing users of safety and efficiency. This guarantee arises from the principle that 60 drops per minute from the drip chamber equals one mL of fluid infused into the patient. Suppose this drip rate of infusion is maintained. In that case, the patient will receive the expected medication dose and fluid volume after a particular period.

There is one condition, however, when the said principle does not hold: when a medical staff shifts the gravity-driven micro-drip infusion set to wide-open flow conditions. With a widely opened infusion set such that the countable drops are no longer visible, several changes occur, as enumerated in the preceding. The delivery of medication dose and fluid volume increase, endangering the patient’s life. With a widely opened flow rate, extrinsic factors, such as catheter size, fluid column height, and carrier flow, will come into active play.

Thus, when using the micro drip infusion set, health workers must monitor the drip rate periodically. If the drip rate is countable, then everything is safe. If not, prompt action is needed to correct and restore the right drip rate because, under the wide-open condition, the expected delivery of the correct medication dose and fluid volume no longer holds.

Micro drip infusion set undoubtedly plays a very significant and crucial role in the delivery of drugs and fluids. However, if a medical staff does it incorrectly, it has severe side effects. Using the infusion set requires careful administration of the IV fluid.

With this potential danger, researchers recommend using mechanical pumps to enhance the precision and safety of the infused drug and fluid delivery instead of manual control of gravity-driven infusions, especially for IV vasoactive substances. This recommendation is seriously pushed to prospective and existing users when the assurance of tight monitoring of drip rate in micro drip infusions cannot be made and ascertained.