PUMP INFUSION
GLOSSARY
- Cannula: Short rubber tube or other material that is applied to various medical and laboratory devices, such as that used in medicine to evacuate or introduce fluids into the body.
- Occlusion: Closing or narrowing that prevents or hinders the passage of a fluid through a pathway or conduit of the organism.
- Peristaltic: The peristaltic movement or peristalsis, is what has the property of achieving contraction, and in the field of Biology can be defined as a successive series of contractions that are made in the process of digestion.
Operating principle
An infusion pump is an electronic device capable of
supplying, through its programming and in a controlled manner, a certain
substance intravenously to patients who, due to their condition, require it.
The use of these devices is very important because they
reduce the percentage of human errors in the intravenous drug supply,
regulating in a rigorous way the flow of liquids inside the patient under a
positive pressure generated by the pump.
The pumps provide greater accuracy and safety in the
infusion of drugs than traditional flow control methods (controllers), are
capable of exceeding small occlusion pressures, can overcome the resistance of
the antibacterial filters and arterial lines to the infusion and They can
infuse drugs with great precision at very low speeds.
Peristaltic pumps: They work by pressing a flexible bag or tube to produce movement of the liquid that is inside a container. Two modalities can be found within this classification, linear peristaltic pumps and rotary pumps. Linear peristaltic pumps have a line of finger-shaped discs that compress the tube into a wave form of continuous motion, forcing fluid out of the container toward the patient. Rotary peristaltic pumps use a rotor that presses the liquid into the tube through rollers through a semicircular passage.
Syringe pumps: Preferred when it is required to supply low volumes and low flow rates. These pumps push the plunger of the syringe at a controlled rate to deliver the substance to the patient. The supply rate can be continuous or in steps that provide boluses in a certain time. The syringe is placed in the pump with the plunger fitted on the plunger holder. As the embolus advances, the syringe empties.
1. Total volume to be infused
Infusion pumps allow the user to select the volume to be infused (VTBI). If this limit is reached before the liquid source ends, most pumps trigger an alarm and continue to infuse liquid into a minimal infusion form known as KVO (keep vein open), for the purpose of prevent the intravenous or intra-arterial cannula of the patient from being blocked by thrombi.
2. Alarms
- Drip alarm. It is activated in case the drip chamber registers an increase or decrease in the programmed flow rate, or a speed of the medication has been introduced during the programming which may result in a delivery profile that is too low for that medication.
- Air alarm In some systems also called vacuum alarm. The sensor can be found inside or outside the system. Record the presence of air in the infusion tube. The delivery of the pump container size is complete, or the pump has detected 2 ml of air in the line.
- Battery alarm. In infusion systems that have their own rechargeable power source when connected to the power source, this device is activated when the power reserve is close to a critical level of operation, after which the pump devices are inaccurate or, not functional.
- Standby alarm. Also called reminder alarm. It works with a time device that triggers an audible alarm when the infusion is temporarily suspended.
- Volume alarm Used in most infusion pumps, by means of audible and / or visible devices. It is activated when the infusion of the volume selected by the user is completed. Start infusion in KVO mode.
- Alarm due to overuse of air-liquid discharge. In multiple infusion pumps, this device is operated when the specified purge limit of the system has been exceeded.
- Alarm by occlusion. The system detects an occlusion between the pump and the patient.
Many infusion devices contain self-diagnostic programs to facilitate the initiation of an infusion and to alert the user of existing problems or impairments.
Characterization of the sensor
To know how the engine works, we did a characterization, where we measured the amount of volume thrown in a minute with different pwm.
the regression was this:
In the regression equation the variable "x" is replaced by "volume/tiem", so that when the user wants work for more than one minute, the machine works correctly.
Programming Code
Call libraries to LCD and matricial keyboard
Code of the keyboard, we declared a pair of constants rows and columns of the keyboard, and ones arrays for indicate to the library what pins of arduino correspondence to rows and columns of the keypad.
We defined what symbols correspondence to each position of the keys too.
First, we pass the characters to numerical value, after we create a void to save in a matrix the numerical values and with this is with the that we can able to work.
To start, the user set the volume, if this volume have a values between 11ml and 1000ml, we
save the volume value in the variable “volumenval”.
Then the user set the time(minutes) in which he wants the volume to be entering into the patient, if the time is between
1 and 60, the time will save into a variable “tiempoval”, then we convert this time to seconds and we put this value and the value of "volumenval" in the sensor characterization equation to start to work.
we did two alarms to the pump infusion, this alarms are occlusion and when the machine haven't enough water. this alarms were do with two infrared sensors that were located in strategic parts of the machine.
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