경희대학교 (Kyung Hee University)
Analysis of Irrigation Pressure According to Flow Rate in Syringe-Based Wound Irrigation Using Computational Fluid Dynamics: A Pilot Study
Wound irrigation applies constant pressure of an irrigating fluid to the wound bed to remove bacteria, necrotic tissue, and debris. The recommended pressure is 8–15 psi, but syringe-based irrigation studies have shown wide variations among practitioners. Clear guidance is needed. This pilot study used Computational Fluid Dynamics simulations to provide foundational data on optimal pressure under different conditions. Pressure and flow dynamics were analyzed using a 19G needle. Variables included irrigating solution (0.9% sodium chloride, 10% povidone-iodine), syringe-to-wound distance (2 or 10 cm), and angle (45° or 90°). Flow rates of 0.5–5.0 cc/sec were tested with Ansys CFX software, using mL/s and psi units. For 0.9% sodium chloride, a 4.0–5.0 cc/sec flow rate maintained 8–15 psi at 90°, both at 2 cm and 10 cm. For 10% povidone-iodine, optimal rates varied: 5.0 cc/sec at 2 cm/45°, and 4.0–5.0 cc/sec at 2 cm/90° or 10 cm/90°. This pilot study provides guidance for syringe-based wound irrigation, showing that irrigation pressure depends on multiple factors and that optimal flow rates vary with angle and distance.
Evaluating pulsatile flushing by pushing method and catheter size for educating nurses on peripheral vascular patency: A computational fluid dynamics simulation analysis
The purpose of this study is to present gauge-specific, bedside pulse-flushing settings that maximize peripheral IV catheter patency while keeping vessel wall shear within safe limits. As a methods anchor, computational fluid dynamics simulated normal-saline boluses with brief pauses to quantify how flush volume, delivery speed, and rhythm affect blood–saline mixing, flow behavior, and wall shear stress in 20G, 22G, and 24G catheters. Results show that larger, faster pulses improve cleansing but also raise shear and can exceed safe thresholds, so efficacy must be balanced against safety; accordingly, the study recommends 1.0 mL over 1 second for 20G, 0.5–1.0 mL over 1 second for 22G, and 0.5 mL over 1 second for 24G, each followed by a 0.4-second pause to maintain a consistent flush–pause rhythm. Clinically, tailoring volume, speed, and rhythm to catheter gauge and context and maintaining a steady flush–pause pattern helps reduce occlusions and complications without unnecessary force and provides a foundation for standardizing flushing education.
Analysis of the urine flow characteristics inside catheters for intermittent catheter selection
The purpose of this study is to establish scenario-based criteria for selecting catheter size in adult intermittent catheterization by determining how catheter caliber (12–18 Fr), bladder pressure (5/20 cmH₂O), urine temperature (20/37/42 °C), and urine profile (normal, bacteriuria, proteinuria, diabetes-associated) govern urine velocity and flow. As the methods anchor, we performed a CFD-based three-dimensional steady analysis with inlet (bladder pressure)–outlet (atmospheric) boundaries and no-slip walls, modeling urine as a Newtonian fluid parameterized by viscosity and specific gravity according to type and temperature, and computed flow rate, velocity fields, and wall shear stress. Results showed that flow increased with larger catheter diameter and with higher bladder pressure and urine temperature; low-viscosity bacteriuric urine flowed the fastest, diabetes-associated high-viscosity urine the slowest, and hydraulic resistance was dominated by wall friction. Clinically, by providing quantitative evidence of “flow by catheter size” that incorporates viscosity differences linked to urine specific gravity, this study enables evidence-based catheter selection: nurses can use urinalysis results (specific gravity and profile) and clinical context to choose a smaller diameter to minimize mucosal trauma when appropriate, or step up one size when delayed drainage is anticipated.
Preliminary Analysis of Arteriovenous Fistula Wall Pressure Influenced by Cannulation Angle, Blood Flow Rate, and Structural Characteristics in Hemodialysis Nursing
This pilot study was conducted before computational fluid dynamics simulations to generate evidence for safe arteriovenous fistula (AVF) cannulation in hemodialysis nursing. Using a radiocephalic AVF model and a 15G needle (20 mm or 25 mm), we calculated clinically applicable cannulation angles and vascular wall pressure based on AVF inner diameter (2, 4, 6, 8 mm), subcutaneous depth (3, 6 mm), insertion angle (1°–45°), and blood flow rate (200–400 mL/min). Pressure was estimated using a problem-specific equation derived from Bernoulli’s principle. No safe cannulation method was identified for a 2-mm AVF. Flow rates ≥300 mL/min produced excessive wall pressure, indicating increased stenosis risk. For inner diameters of 4–8 mm, pressure remained relatively stable despite variations in cannulation angle and flow rate: 4 mm ranged from 7027.2 Pa (52.7 mmHg) to 12,918.8 Pa (96.8 mmHg); 6 mm from 6066 Pa (45.4 mmHg) to 11,153.4 Pa (83.6 mmHg); and 8 mm from 5772.1 Pa (43.2 mmHg) to 10,597.1 Pa (79.4 mmHg). By applying fluid mechanics to nursing science, this study offers foundational data to guide safe AVF cannulation and support future research aimed at reducing cannulation-related stenosis in patients undergoing hemodialysis.
Analysis of Infusion Volume Error Rates with Increasing Number of Connected Fluids and Infusion Flow Rates: Implications for Clinical Skill Training
This study is a control volume analysis designed to quantify infusion volume error rates as fluid volume and flow rate increase during intravenous fluid therapy nursing. We modeled a system comprising the infusion fluid, an intravenous accessory manifold, peripheral venous catheter, central venous catheter, peripheral vein, and central vein, and, based on the Bernoulli equation with frictional losses, formulated and analyzed characteristic equations ranging from a single-line connection to configurations with four parallel connections. The numerical error rates reported in this study are therefore model-derived outputs across the defined flow interval. When the infusion fluid type and catheter size were held constant, infusion volume error rates increased with greater fluid volume and higher flow rates. In addition, smaller internal diameters of venous catheters were associated with higher infusion volume error rates, independent of fluid volume and flow rate. Finally, comparing peripheral versus central venous access during increasing fluid volume and flow rate, central venous access yielded lower infusion volume error rates. Based on these findings, it is necessary to predict infusion volume error rates and, accordingly, set a compensation rate higher than the nominal infusion rate, as well as to educate nurses to anticipate and manage flow reductions arising from differences in venous catheter characteristics. Furthermore, if clinical practice guidelines were to include peripheral IV-specific strategies for correcting infusion volume error and clear guidance on infusion rate adjustment, nurses could manage fluids in a more scientific and standardized manner, thereby enhancing clinical applicability and patient safety.
Analysis of the flow rate based on length and diameter of infusion set and peripheral venous catheter in rapid fluid therapy
This study aimed to provide fundamental data for nurses on rapid fluid therapy by analyzing the flow rate according to the size of peripheral intravenous catheters and the length and inner diameter of the infusion sets. Volumetric analysis indicated that, even when using peripheral intravenous catheters with a smaller inner diameter, the necessary fluid could be sufficiently delivered to the patient within a predetermined time by adjusting the length and inner diameter of the infusion sets, thereby achieving rapid fluid therapy. These results suggest that predicting the hourly flow rate based on the size of the peripheral intravenous catheter and the length and inner diameter of the infusion set during rapid fluid infusion can enable nurses to make autonomous decisions and efficiently manage their time in clinical settings.
Analysis of Drainage Volume in External Ventricular Drainage Based on Intracranial Pressure and Drainage Catheter Size for Clinical Nurses
The purpose of this study is to provide predictable setup guidance in adult EVD by quantifying how intracranial pressure (ICP), drainage catheter size, and system height relative to the foramen of Monro determine CSF drainage speed and volume. As a methods anchor, we modeled the drip chamber–tubing–catheter–collection system under standardized adult conditions using the continuity equation and a Bernoulli model with friction correction. Results show a consistent directionality: drainage increases with larger catheter size, lower system height (below Monro), and higher ICP (e.g., at 0 cm height, a 9 Fr catheter drains 5 mL in about 18 seconds). Clinically, re-zeroing height after any position change, pairing the largest feasible bore with a lower height, and intensifying monitoring when using large-bore catheters help achieve target drainage while improving patient safety.
Comparison of fluid flow rates by fluid height and catheter size in normal and hypertensive blood-pressure scenarios
The purpose of this study is to quantify how bag height (0–100 cm), catheter gauge (16–24G), fluid viscosity (saline, Hartmann’s, Plasma, hetastarch, albumin), and venous pressure (normal vs. elevated) determine gravity-driven infusion so clinicians can set predictable bedside parameters. As a methods anchor, a control-volume model at 22 °C applied the continuity and Bernoulli equations with Darcy–Weisbach friction under a laminar-flow assumption to estimate flow across variable combinations. Directionally, higher bags, larger-bore catheters, and lower-viscosity fluids increased flow, whereas elevated venous pressure reduced flow and may require a higher bag to achieve positive infusion; under normal venous pressure, predicted rates span roughly 58.2–10,743.2 cc/h with diminishing returns at greater heights due to frictional losses. Clinically, define the target rate, pair the largest feasible bore (often 16–18G) with sufficient height, consider a pump or added height for viscous solutions, and reference height to the insertion site with re-zeroing after any position change.
Control Volume Analysis of the Infusion Rate in Cephalic and Median Cubital Veins Based on Infusion Bag Heightand Peripheral Venous Catheter Inner Diameter: Application of Bernoulli’s Equation and Consideration of Frictional Forces
The purpose of this study is to determine how, in gravity-driven infusion, infusion bag height (0.8–1.5 m), peripheral IV catheter gauge (14–26G), and venous site (cephalic vs. median cubital) govern flow rate, providing a basis for predictable bedside rate setting and standardized device selection. As a methods anchor, the drip chamber–tubing–catheter–vein system (0.9% saline at 22 °C) was modeled with a control-volume approach using the continuity and Bernoulli equations with Darcy–Weisbach friction under a clinically appropriate laminar-flow assumption. Directionally, greater height, a larger bore (smaller gauge number), and the cephalic site produced higher predicted flow, with diminishing returns at higher elevations due to frictional losses. Clinically, matching the largest feasible gauge to an appropriate bag height for the target rate, re-zeroing height to the insertion site after any position change, and considering a parallel line when upsizing is not possible enables predictable rate management and supports standardization and patient safety.
Analysis of flow rate of continuous bladder irrigation according to the height of the irrigation infusion set
The purpose of this study is to provide a clinical basis for predicting and controlling flow in continuous bladder irrigation (CBI) by quantifying how irrigation bag height, indwelling catheter size (18–24 Fr), irrigant temperature (22 °C/4 °C), and bladder pressure (5/20 cmH₂O) affect flow. As a methods anchor, the drip chamber–tubing–catheter–bladder system was modeled as a single control-volume line, and flow for each variable combination was calculated using the Bernoulli equation with Darcy–Weisbach friction. Directionally, raising the bag, using a larger French size (wider bore), and warming the irrigant increased flow, whereas higher bladder pressure or insufficient height could cause backflow; for example, under room-temperature, low-pressure conditions at 1.2 m, predicted flows for 18–24 Fr were about 0.99–1.24 mL/s, and with a 4 °C irrigant the gain at the same height was smaller. Clinically, setting height relative to the insertion site and re-zeroing after position changes, then adjusting height, catheter size, and solution temperature to match the target effluent color (light pink to clear), allows reasonable planning of hourly volumes and replacement intervals without a pump.
Analysis of flow rate and pressure in syringe-based wound irrigation using Bernoulli's equation
The purpose of this study is to define practical, bedside-ready settings for syringe-based wound irrigation that reliably achieve the recommended cleansing pressure of about 8–15 psi by quantifying the optimal combinations of needle gauge, flow rate, and needle height. As a methods anchor, the space from the needle tip to the wound surface was treated as a single control volume at 22 °C, applying the continuity and Bernoulli equations with Darcy–Weisbach friction to evaluate how flow rate, needle inner diameter (14–29G), and needle height above the wound (10–15 cm) determine wound-surface pressure. Directionally, increasing jet velocity—by raising flow or using a smaller-bore needle—elevates pressure, and greater needle height further increases pressure; practical ranges that meet 8–15 psi are ~3.5–<4.8 mL/s for 19G, 2.6–<3.5 mL/s for 20G, 1.3–<1.8 mL/s for 22G, and 0.5–<0.6 mL/s for 25G, whereas 14–18G generally cannot reach the target and gauges ≥27G tend to exceed 15 psi even at minimal settings. Clinically, the findings show that needle diameter and actual flow—not syringe size—principally govern irrigation pressure, providing quantitative guidance to combine gauge, flow, and height in standardized protocols and to fine-tune flow within the target pressure range based on patient and wound characteristics.