Intravenous Therapy Basics

Intravenous Therapy

• Intravenous therapy, or IV therapy, involves directly administering liquid substances into a vein.
• The term "intravenous" means "within a vein".
• IV therapy is commonly called a drip due to the use of a drip chamber in many systems.
• Drip chambers prevent air from entering the bloodstream, mitigating the risk of air embolism.
• Drip chambers also allow for estimation of the flow rate.
• Compared to other administration methods, the intravenous route delivers fluids and medications faster.
• Some medications and blood transfusions must be administered intravenously.

Basic Infusion Systems

• Basic infusion systems use gravity for flow.
• Flow is controlled using a roller clamp.
• A drawback of basic systems is the difficulty in accurately setting and controlling the infusion rate.

Intravenous Access Devices

• The most common method in hospitals and pre-hospital settings is intravenous access.
• A peripheral IV line utilizes a short catheter, a few centimeters long.
• The catheter is inserted through the skin into a peripheral vein, outside the chest or abdomen.

Types of Intravenous Devices

• Open Loop System: Drug delivery is determined by experience and mathematical computation.
• Open Loop System: The fluid is delivered at a changed rate.
• Closed Loop System: Employs appropriate transducers to measure the effect of drugs.
• Closed Loop System: Automatically adjusts the delivery rate to the desired level.

Types of Infusion

• Technicians or nurses input infusion type details into pump's user interface.
• Continuous Infusion: delivers small pulses of infusion, typically between 20 nanoliters and 100 microliters, depending on the pump's design.
• Continuous Infusion: The pulse rate depends on the programmed infusion speed.
• Intermittent Infusion: Involves infusing a volume of fluid or medication over a set time at prescribed intervals, followed by a pause until the next dose.
• Patient-Controlled Infusion: Operates on demand, usually restricted by a preprogrammed ceiling to avoid intoxication.
• Patient-Controlled Infusion: The patient controls the rate via a pressure pad or button.
• Patient-Controlled Infusion: The common method for patient analgesia.
• Total Parenteral Nutrition (TPN): Also known as total nutrient admixture (TNA).
• Total Parenteral Nutrition (TPN): Used when significant nutrition can't be obtained through other routes.
• Total Parenteral Nutrition (TPN): Usually requires an infusion curve that mimics normal mealtimes

Types of Pumps

• Two basic pump classes exist.
• Large volume pumps can deliver enough nutrient solutions to feed a patient.
• Small-volume pumps inject hormones like insulin, or other medicines like opiates.

Infusion Pumps

• Infusion pumps are generally electrically powered infusion devices.
• Infusion pumps Use pumping action to infuse fluids, medication, or nutrients into a patient.
• Infusion pumps are suitable for intravenous, subcutaneous, enteral, and epidural infusions.

Desirable Specifications of Infusion Devices

• Reliable and electrically safe
• Able to deliver infusion accurately and consistently
• Easy to set up and use
• Portable
• Powered by both battery and mains
• Capable of alerting to line occlusion and the need to re-change the syringe
• Able to clearly display the rate of infusion and volume infused

Infusion Pump Design

• Some infusion pumps are designed mainly for stationary use at a patient's bedside.
• Others, called ambulatory infusion pumps, are designed to be portable or wearable.

Infusion Pump Types

• Volumetric Pumps
• Syringe Pumps

Volumetric Pumps

• Preferred for medium and high flow rates and large volumes.
• Generally not suitable for rates less than 5ml/h.
• Variable short term accuracy.
• Specialized volumetric pumps exist for ambulatory use and epidural infusions.

Parts of Infusion Pumps

• Saline Stand
• Saline Bottle
• IV Tube

Techniques for Pumping Action

• Peristaltic action squeezes the fluid tubing in a controlled manner to force the fluid down the tubing, using fingers or rollers on a drum.
• A second method involves using a cassette (or chamber) that fills with fluid and then empties it out by the pumping mechanism in a controlled manner.

Peristaltic Pumps

• Peristalsis - natural involuntary wave-like muscle contractions moving food through the digestive tract.
• Operate by batching a specific volume of water and forcing it along a tube.
• Employs a rotor attached to an external circumference that compresses and releases a flexible tube with rollers.
• The action creates a squeezing motion, drawing fluid through the tubing.
• Positive Displacement Pump (PDP) features 3 Parts: Pump Head, Drive Mechanism, and Tubing.

Controller Board

• The controller board is the main board of a syringe infusion pump.
• The board includes a motor controller, detector circuitry, power supply, battery charging monitoring, key pad, and display controller circuitry.
• It contains a microcontroller CPU with ROM, RAM, and a data converter.
• The board interconnects with PCBs to control and monitor the proper functioning.

Motor

• Earlier infusion systems utilized a DC motor to drive the piston pump at a rate set by the unit.
• Current systems use a stepper motor and control angular velocity with digital electronics.
• The internal diameter of the syringe is stored in ROM.
• The applicable internal diameter of the syringe can be loaded as per the setting of syringe size and brand selected.

Motor Controller

• It monitors and detects the motor's rotation via encoder.
• It controls the actual speed according to the programmed setup.
• The main CPU sends motor rotation pulses to drive the motor while an encoded input pulse from the motor is sent to the CPU to calculate and control the drive.

Pump Unit

• A stepper motor drives the pump.
• A motor controller board drives the motor by applying a specific number of pulses.
• Direction of rotation and pump speed are monitored.

Power Supply Module

• It has an AC line input and transformer.
• Generates DC voltages, including +/- 5VDC, +/- 12 VDC, +/- 15VDC, and 7.5VDC.
• DC voltages are achieved after step-down transformation and bridge rectification.
• Power is supplied to each PCB and the battery charging circuitry.

Battery Operation

• A fully charged battery provides a constant supply to the unit.
• CPU monitors a fully charged battery.
• The system monitors charging current, discharge current, and time, activating a battery alarm if the minimum voltage requirement is not reached.

Front Panel

• The front panel of the pump includes an LCD display and keypad control.
• The LCD displays information in plain text on a green background, showing the status of the unit.
• It displays information on AC mains or battery operation, alarm status, history of drug infusions, time intervals, bolus doses, and the quantity delivered to the patient.
• The keypad enables data entry for patient-specific drug delivery and setup.

Syringe Pumps

• Syringe pumps are generally used for low volume, low flow rate infusions.
• Syringe pumps offer good short term accuracy.
• Syringe pumps tend to have long start up times at low flow rates,requiring the line to be primed and purged before connecting to the patient.
• Alarms: Syringe pumps alarms include end/near end of infusion, drive disengaged, occlusion, and low battery.
• Syringe pumps are specialised for ambulatory use, PCA, sedation, and insulin delivery.

Safety Features

• Pump-based anti-free-flow clamp
• Upstream sensor
• Downstream pressure sensor
• Air sensor
• Set-based Anti-free-flow clamp
• Downstream fixing clip of the pumping element
• Upstream fixing clip of the pumping element
• Peristaltic pump compartment, removable for cleaning

Detector Circuit

• It includes sensor circuitry for syringe size, occlusion detection, syringe plunger detection, and low power detection.
• Lifting the syringe barrel clamp activates the sensor (potentiometer) integrated with the syringe barrel shaft, causing the resistor value to change with rotation angle.
• The syringe plunger clamp moves along with the nut drive shaft of the motor.
• An occlusion triggers a reverse load, obstructing the plunger's movement, activating an equipped occlusion sensor.
• The syringe plunger clamp operates the syringe plunger sensor (micro switch).
• The respective information is sent to CPU if the syringe is clamped and the sensor is ON
• The controller recognizes the current power source - external or internal - and checks the required voltage and current.
• The detector circuit monitors conditions and sends the information to CPU

Main Menu Options

• Standard Mode
• Status of Infusion
• Customized Special Functions
• Customized Options

Multi dose Mode

• Multi dose Mode allows 2 to be programmed at equally spaced intervals on the same Syringe Module
• Multi dose Mode allows delivery of multiple, equal doses from the same syringe at regularly scheduled intervals.

Near End of Infusion (NEOI)

• The NEOI option configures an alert to sound 1-60 minutes before infusion ends.

Occlusion Pressure

• It offers a full range of downstream occlusion detection options.
• With a pressure sensing disc, the selectable occlusion alarm threshold can be set between 25 and 1000 mmHg in 1 mmHg increments.
• Without a pressure sensing disc, the occlusion alarm threshold can be set to low, medium, or high.

Occlusion Alarm

• Occurs when pump is unable to sustain set flow rate and pressure in line increases
• Caused by partial/complete blockage in delivery tubing (kinked tube, clamp/tap closed) or cannula (clotted off, position changed).

Air-in-Line

• Volumetric pumps carry the risk of air delivery from poor priming, upstream leaks, or pumping action drawing air from the solution.
• Volumetric pumps have a mechanism for preventing pumping of air or an air-in-line detector & alarm.