Precision and Accuracy of Pumps used in Shoulder Arthroplasty

Completed Research

Precision and Accuracy of Pumps used in Shoulder Arthroplasty

Background    

Arthroscopic pumps have been routinely used for over three decades. Their accuracy however has recently come into question and they have been shown to deliver excessive pressure without alerting the user.

Whenever arthroscopy is performed, complications can arise from large volumes of extravasated irrigation fluid1. Known as “Intra-Abdominal Fluid Extravasation (IAFE)” this is a serious and potentially life-threatening complication[3]. Compression of the neck veins can follow if it occurs in the shoulder and it can be life threatening if it occurs in the hip[3].
The aim of this 2015 study was to confirm this was the case and identify the potential sources of contamination within the surgical field in shoulder arthroplasty.

Previous studies have shown a correlation between higher pump pressures and increased risk of IAFE with actual pump pressures significantly higher than displayed pump pressures[3]. The take home message from this research is that excessively high pump pressures are to be avoided3 and the physical and physiologic signs of fluid extravasation monitored throughout arthroscopy[4].

For surgeons to follow this advice, however, and maintain strict control of pump settings[3] or keep pressures as low as possible[1] it is crucial to know the actual pressure a pump produces at a given setting – a task that is confused by the fact that recommended pressure ranges vary between pump manufacturers. This is further hampered by the fact that many arthroscopic pumps actually have control algorithms that maintain a higher pressure than is set by the user – a difference which increases as the pressure setting increases although the user is not alerted to this fact. One study in knee arthroscopy showed that pumps actually subjected the joint to pressures more than twice the user setting[5].

The purpose of this study is to investigate three of the pumps most commonly used in shoulder arthroscopy and compare their pressure measurement accuracy in order to inform pump safety.

Objectives

The primary objective was to determine the accuracy of 3 arthroscopic pumps by comparing intra-articular pressure as measured by the pumps with actual intra-articular pressure as measured by arterial line. The secondary objective was to determine which of the pumps is the most accurate by comparing their error rates.

Design

This was a non-randomized observational study.

Study Procedure

Consecutive patients presenting to an elective orthopaedic consultation indicated for arthroscopy were considered eligible for this study. Informed consent was obtained. During the procedure the pressure within the joint was measured using an arterial line as a pressure sensor. The arterial line was connected to the patient’s spinal needle yielding a measure (in mmHg) of intra-arterial pressure. This measurement was noted. The pressure displayed on the arthroscopic pump (in mmHg) was also noted along with the brand and model of the pump in use. The measurements were then compared.

3 pumps were tested:
• Conmed Linvatec 24K
• Stryker Crossflow
• Arthrex Dual Wave

Inclusion Criteria

  • Patients who have consented for elective shoulder arthroscopy
  • Patients who are capable of and have given informed consent to participate in this study

Exclusion Criteria

  • Patients incapable of giving informed consent to participate in this study

Statistical Procedure

Univariate and multivariate analyses will be used to determine the correlation between systemic administration of TXA and the selected outcome criteria. Subgroup analysis will be carried out between the different types of prosthesis (reverse versus anatomic). Any P value <0.5 will be considered statistically significant.

Ethics and Governance

Approved by St Vincent’s Hospital Human Research Ethics Committee to be undertaken at the Mater Hospital Sydney. HREC reference HREC/16/SVH/212.

Approved by North Shore Private Ethics Committee to be undertaken at North Shore Private Hospital. HREC reference NSPHEC 2016-LNR-003.

Results

The Conmed 24K® pump (Figure 1) showed no difference between the mean intra-articular pressure and set pressure with TIPS (0.98 ± 0.02 fold, P<0.001), whereas the intra-articular pressure was significantly higher than the set pressure without TIPS (1.30 ± 0.13 fold, P<0.001). The mean differences between the displayed pump pressure and measured intra-articular pressure was (2.9 ± 2.6 mmHg) with or (29 ± 16 mmHg) without TIPS.

The Stryker Crossflow® pump (Figure 2) showed no difference between the mean intra-articular pressure and the set pressure in standard mode (0.98 ± 0.02 fold, P<0.001), however the intra-articular pressure was significantly higher than the set pressure in dynamic mode (1.82 ± 0.08 fold, P<0.001). The mean differences between the displayed pump pressure and measured intra-articular pressure were (7.7 ± 2.6 mmHg) in standard or (80 ± 19 mmHg) in dynamic mode.

The Arthrex Dual Wave® pump (Figure 3) showed significantly higher intra-articular pressure than the set pressure (2.19 ± 0.06 fold, P<0.001). The mean differences between the displayed pump pressure and measured intra-articular pressure were (76 ± 25 mmHg).

Intra-articular pressure was closest to the set pressure (Figure 4) when using the Conmed 24K® pump with TIPS and the Stryker Cross­flow® pump on standard mode, followed by the Conmed 24K® pump without TIPS.

Our findings suggest that actual intra-articular pressure can be more than double the set pressure on some arthroscopic pumps. Measuring intra-articular pressure can aid in adjusting the set pressure. To achieve a ‘true’ pres­sure of 60 mmHg, we suggest setting the Arthrex pump to 25-30 mmHg, the Stryker pump to 55-60 in standard mode and the Conmed pump to 55-60 if using the TIPS. This could minimize the risk of fluid extrava­sation into the soft tissues and any further related complications.

References

  • Stafford, G. H., Malviya, A., & Villar, R. N. (2011). Fluid extravasation during hip arthroscopy. Hip International, 21(6), 740-743.
  • Bomberg, B. C., Hurley, P. E., Clark, C. A., & McLaughlin, C. S. (1992). Complications associated with the use of an infusion pump during knee arthroscopy. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 8(2 ), 224-228.
  • Kocher, M. S., Frank, J. S., Nasreddine, A. Y., Safran, M. R., Philippon, et. al. (2012). Intra-abdominal fluid extravasation during hip arthroscopy: A survey of the MAHORN group. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 28(11), 1654- 1660.
  • ECRI Institute. (2010). Arthrex AR-6400 and AR-6475 arthroscopy pumps can deliver excessive pressure without alerting user. Health Devices, 2010(April), 134-136.
  • Fowler, J., & Owens, B. D. (2010). Abdominal compartment syndrome after hip arthroscopy. Arthroscopy: The Journal of Arthroscopic and Related Surgery, 26(1), 128-130.
  • National Statement on Ethical Conduct in Human Research (2007) – Updated December 2013 (the National Statement), Commonwealth of Australia, Canberra.

Lead Investigator:

Dr Ben Cass

Commenced:

2016

Completed:

2016

Published:

Submitted to Arthroscopy, June 2017

Presented:

Swiss Society of Orthopaedics and Traumatology Annual Congress, June 2017

Category:

Completed Research

{Updated June 2017}

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