A Study of the Automated Fluid Irrigation using a Gravity Pump for Arthroscopy and Cystoscopy

Abstract

The irrigation fluid given during arthroscopy and cystoscopy provides pressure and flow rate between the joint space and the bladder, thus pushing the debris occurring during surgery. The crisp view of the surgical field is clear. This study aims to investigate the operation of the automated fluid irrigation using a gravity pump. The advantage of this system is the safer use of the gravity pump, which reduces the risk of malfunctions from the electric pump that may cause damage to nearby tissues during surgery. Another advantage is to provide a steady fluid flow. From the principle of Bernoulli's equation, the design of the automated gravity pump was to maintain the difference between operating height and irrigation fluid elevation (Z₁). The 0.194 kg of lost mass, m_loss, was calculated and used to control motors in lifting the 0.011 mH₂O steps periodically for both left and right buckets of irrigation fluid to compensate for lost irrigation fluid elevation. This process kept going until the irrigation fluid of each bucket was completely exhausted and alternating operations throughout the surgery. In the study’s design, the pressure heads of the operating automated fluid irrigation were set at 60, 80, and 100 mmHg, the Z₁ and the pressures from the pressure gauge were measured. The above results were compared between both pressure heads, which were converted from the measured Z₁ and pressure gauge, and the pressure heads, which were set as mentioned previously.

Finally, automated fluid irrigation was recorded alternating between left and right buckets to irrigate fluid at the pressure heads. This test ended when the second irrigated bucket was exhausted. The results of automated fluid irrigation showed that measured Z₁ was in the range of 0.811 to 0.822 mH₂O with -0.58% to 0.76% difference compared with set pressure head at 60 mmHg; in the range of 1.082 to 1.093 mH₂O with -0.51% to 0.48% difference compared with set pressure head at 80 mmHg; and in range of 1.082 to 1.093 mH₂O compared with -0.33% to 0.47% difference compared with set pressure head at 100 mmHg. It was also shown that pressures from the pressure gauge were 0.080, 0.105, and 0.135 bar with 0.00%, -1.55%, and 1.26% difference compared with set pressure head at 60, 80, and 100 mmHg, respectively. The process of automated fluid irrigation showed that this command processing unit worked properly to control motors and solenoid valves as designed by lifting to get designated head pressure and alternating the left bucket to right bucket to irrigate fluid continuously. It was concluded that the lost mass was used to determine the working conditions of this automated fluid irrigation with a gravity pump. It worked properly as designed to automatically control the motors and solenoid valves for fluid irrigation at the set pressure head. Therefore, this equipment could give clear image quality, continuous fluid irrigation according to the doctor's requirements, and reduced risk of abnormal pressure from the electric pump during surgery.