LETTER TO EDITOR
Year : 2012 | Volume
| Issue : 4 | Page : 431-433
Troubleshooting management for bleedback after arterial cannulation used for invasive hemodynamic monitoring
Dheeraj Kapoor, Meghana Srivastava
Department of Anaesthesia and Intensive Care, Govt. Medical College and Hospital, Chandigarh, India
Department of Anaesthesia and Intensive Care, Govt. Medical College and Hospital, 1207, Sector 32 B, Chandigarh 160 030
Source of Support: None, Conflict of Interest: None
|Date of Web Publication||10-Jan-2013|
|How to cite this article:|
Kapoor D, Srivastava M. Troubleshooting management for bleedback after arterial cannulation used for invasive hemodynamic monitoring. Saudi J Anaesth 2012;6:431-3
|How to cite this URL:|
Kapoor D, Srivastava M. Troubleshooting management for bleedback after arterial cannulation used for invasive hemodynamic monitoring. Saudi J Anaesth [serial online] 2012 [cited 2023 Jan 30];6:431-3. Available from: https://www.saudija.org/text.asp?2012/6/4/431/105902
Arterial cannulations are commonly done for invasive continuous hemodynamic monitoring in patients in critical care settings and undergoing major surgeries with anticipated perioperative hemodynamic instability owing to major fluid shifts, significant blood loss, autonomic disturbances, and cardiovascular diseases. It also provides a site for arterial blood sampling and cardiac output determination. Yet, arterial cannulations are not without problems and complications. Most common problems encountered are bleedback and air bubble in pressure monitoring line, dampened waveforms, thrombosis, hematoma, bleeding, and infections.  Here, we report the problem of bleedback in pressure monitoring line while doing invasive hemodynamic monitoring, due to the use of nonstandardized, low-cost pressure monitoring tubing and its troubleshooting management.
A 45-year-old male patient (ASA grade 3) with hypertensive intracranial bleed (posterior communicating artery aneurysm) was posted for urgent surgical clipping in emergency operating room (OR). After institution of general anesthesia the patient was planned for arterial and central venous pressure (CVP) cannulations for continuous hemodynamic monitoring. Due to nonaffordability of patient a 20 G intravenous(IV) cannula (Vein Cath™ GS-3024, Romsons® , India) was inserted in the left radial artery under all aseptic precautions after performing positive modified Allen's test.  Low-cost pressure monitoring tubing (Shanghai Kohope Medical Devices™, China) was attached to the cannula and then connected to the arterial pressure monitoring transducer (BD DTXPlus™, USA) for continuous arterial blood pressure monitoring. After 15 min of the placement, dampening of the pressure waveform with bleedback from arterial cannula into pressure tubing was observed, reaching all the way up to the transducer [Figure 1]. The arterial cannula and pressure tubing were dynamically flushed with heparinized saline but the problem persisted. To counteract the problem we immediately placed two three-way stopcocks (Smiths Medical Medex® MX5311L, UK) on both ends of the pressure monitoring (PM) tubing, one between the PM tubing and arterial cannula [Figure 2] and the other at the junction of transducer and the PM tubing [Figure 3]. Zeroing (setting atmospheric pressure as zero reference point) was done and pressure monitoring system was reactivated. No bleedback was observed thereafter and successful arterial pressures were recorded throughout the surgery and in the postoperative period.
|Figure 1: Bleedback in pressure monitoring tubing and pressure transducer|
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The problem of bleedback with arterial cannulations is described in the literature due to loose connections, a partially deflated pressure bag, or incorrect stopcock position.  The blood flow through vessel column or hemodynamic line is governed by various physical factors as described by Hagen-Poiseuille law (flow = (Pi - Po) r4/8ηl, where Pi - Po = hydrostatic pressure gradient, r = radius of the tubing, η = coefficient of viscosity, l = length of tubing).  Thus blood flow will vary in proportion to pressure gradient and diameter of blood column. The total fluid energy, which is the summation of pressure energy (potential energy), gravitational potential energy (ignored when liquid moves horizontally), and kinetic energy, determines the liquid movement between two points in a tube. Keeping the total fluid energy constant, the lateral hydrostatic pressure (P) is altered due to the changes in the velocity of flow, which in turn changes the kinetic energy. If tube containing fluid narrows in dimension, the velocity of flow, and thereby the kinetic energy increases. This results in decreased potential energy, such that the measured lateral hydrostatic pressure (P) decreases in narrowed section. If tube widens suddenly, the velocity of flow and kinetic energy fall, so P measured increases.  These principles of physics explain why variation in diameter of hemodynamic lines (pressure tubing) might cause backward flow of blood (bleedback) into pressure tubing causing dampening of arterial waveform and faulty blood pressure readings.
According to other studies, radial artery internal diameter is 2.34±0.37 mm. , The 20 G IV cannula used for arterial cannulations has an ID (internal diameter) of 1.1 mm and length of 32 mm, compared with the standard recommended angiocath of 20 G, having ID 1.1 mm and length of 45-60 mm (BD Floswitch™, USA, BD Careflow™, USA). Standard high-pressure tubings used have an internal diameter of 2.5-2.7 mm (B Braun® , Germany, BD® , USA). We observed that the nonstandardized, low-cost pressure tubings generally have an ID of more than 5.0 mm. Sudden and gross difference in ID of arterial cannula and pressure tubing, thus results in problem of bleedback and faulty pressure readings. We have observed that if a three-way stopcock is placed between arterial cannula and pressure tubings, which have an ID of 3 mm, then there is no bleedback from the cannula. The smaller ID of three-way stopcock offers additional resistance such that, the hemodynamic line fluid pressure is enough to counter balance the arterial pressure, and thereby prevents bleedback.
We conclude that in the third world countries, many a times high cost of recommended products restrains their use in poor population, although they remain the standard of care. As such, use of low-cost pressure tubings may be done for arterial pressure monitoring in these circumstances and the common problem of bleedback encountered could be easily prevented by practicing the use of the three-way stopcock on both ends of the pressure monitoring line.
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[Figure 1], [Figure 2], [Figure 3]
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