CADD Legacy Technical Manual Jan 2000

For detailed instructions, specifications, warnings, warranties, and additional information on operating CADD® pumps, please refer to the Operator’s Manual supplied with the product. If you have additional comments or questions concerning the operation of CADD® pumps, please call this number: 800-426-2448. Our staff is available to help you twenty-four hours a day with the programming and operation of CADD® pump infusion systems. The issue date of this Technical Manual is included on the back cover for the user’s information. In the event one year has elapsed between the issue date and product use, the user should contact SIMS Deltec, Inc. to see if a later revision of this manual is available. Issue Date: January 2000

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Table of Contents 1. Introduction ... 1

6. Safety Features and Fault Detection ... 17

Limited Warranty ... 1 Exposing CADD® Pumps to Radiation, Ultrasound, or MRI or use near ECG equipment ... 1

Hardware Safety Features ... 17 Software Safety Features ... 19

2. CADD-Legacy™ Pump Delivery Modes ... 2 Specifications (Nominal) ... 5 Compatible Medication Cassette™ Reservoirs and CADD® Administration Sets ... 7 Remote Dose Cord ... 7

3. Batteries ... 8 Battery Compatibility ... 8 DURACELL® Alkaline Battery Life ... 8

4. Construction ... 11 5. Theory of Operation ... 12 Keyboard Circuitry ... 12 Data Memory in Real Time Clock RAM ... 12 EEPROM ... 12 Battery Backed RAM ... 12 Time Base Circuitry ... 12 LCD Circuitry ... 12 LED Indicator ... 13 Flash PROM Technology ... 13 Audible Alarm Circuitry ... 13 Watchdog Timer Circuit ... 13 Motor Drive/Motor Watchdog Circuit ... 13 Power Circuitry ... 14 Voltage Reference Circuit ... 14 Pumping Mechanism ... 14 Pumping Characteristics ... 15 Air Detector ... 15 Downstream Occlusion Sensor ... 16 Upstream Occlusion Sensor ... 16 Cassette Attachment Detection... 16

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7. Hardware and Software Fault Detection 20 Overview ... 20 Order of Error Code Events ... 20

8. Cleaning and Inspection Procedures ... 21 Inspection Recommendation ... 21 Cleaning ... 21 Battery Contact Cleaning ... 21 Visual Inspection ... 22 Mechanical Inspection ... 22

9. Testing Procedures ... 23 Testing Recommendation ... 23 Changing to Lock Level 0 (LL0) ... 23

CADD-Legacy™ PCA pump ... 23 Air Detector Test ... 25 Upstream Occlusion Sensor Test ... 25 Occlusion Pressure Range Tests ... 25 Accuracy Testing ... 27

CADD-Legacy™ 1 pump ... 29 Air Detector Test ... 30 Upstream Occlusion Sensor Test ... 30 Occlusion Pressure Range Tests ... 31 Accuracy Testing ... 32

CADD-Legacy™ PLUS pump ... 34 Air Detector Test ... 35 Upstream Occlusion Sensor Test ... 36 Occlusion Pressure Range Tests ... 36 Accuracy Testing ... 37

Cleaning and Functional Testing Checklist ... 40

1 Introduction This Technical Manual is intended to provide an understanding of the mechanical and electrical operation of the CADD-Legacy™ PCA, CADD-Legacy™ 1, and CADD-Legacy™ PLUS Computerized Ambulatory Drug Delivery pumps to persons familiar with these devices. The CADD-Legacy™ PCA, CADD-Legacy™ 1, and CADD-Legacy™ PLUS pump Operator’s Manuals should be used in conjunction with this publication for complete information. This manual also outlines cleaning and functional testing procedures that can be performed on the CADD-Legacy™ PCA, CADD-Legacy™ 1, and CADD-Legacy™ PLUS pumps. WARNING: This Technical Manual must be used by Biomedical Technicians only. Do not permit patients to have access to this manual. Do not disclose to the patient the pump’s security codes or any other infomation that would allow the patient complete access to all programming and operating functions. Improper programming could result in death or serious injury to the patient.

IMPORTANT NOTICE: CADD-Legacy™ PCA, CADD-Legacy™ 1, and CADD-Legacy™ PLUS pump operations and safety features are based on a microcomputer design. Inadequate servicing or tampering with the safety features of the pumps may seriously affect performance and safety. For that reason, ALL SERVICING AND REPAIR OF THE CADD-Legacy™ PUMPS MUST BE PERFORMED BY DELTEC OR ITS AUTHORIZED AGENTS. The manufacturer’s warranty agreement shall become null and void if the pump is not used in accordance with the Operator’s Manual and Instructions for Use for the pump accessories; or, the pump is serviced by persons other than Deltec or those authorized by Deltec.

Limited Warranty The limited warranty associated with the CADD-Legacy™ PCA, CADD-Legacy™ 1, and CADD-Legacy™ PLUS pumps can be found in the product literature supplied with the product when originally purchased, which is incorporated herein by reference. DELTEC SPECIFI-

CALLY DISCLAIMS ANY OTHER WARRANTY, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR USE. Deltec further disclaims responsibility for the suitability of the system for a particular medical treatment or for any medical complications resulting from the use of the system. The manufacturer shall not be responsible for any incidental damages or consequential damages to property, loss of profits, or loss of use caused by any defect or malfunction of the system. If you wish to receive additional information about the extent of the warranty on these products, please contact your Deltec representative or call Customer Service at 1-800-426-2448. All recommendations, information, and literature supplied by Deltec with respect to the CADD® product line are believed to be accurate and reliable, but do not constitute warranties. No agent, representative, or employee of Deltec has authority to bind Deltec to any representation or warranty, expressed or implied.

Exposure to Radiation, Ultrasound or Magnetic Resonance Imaging (MRI), or use near ECG equipment CAUTION: • Do not expose the pump to therapeutic levels of ionizing radiation as permanent damage to the pump’s electronic circuitry may occur. The best procedure to follow is to remove the pump from the patient during therapeutic radiation sessions. If the pump must remain in the vicinity during a therapy session, it should be shielded, and its ability to function properly should be confirmed following treatment. • Do not expose the pump directly to ultrasound, as permanent damage to the pump’s electronic circuitry may occur. • Do not use the pump in the vicinity of magnetic resonance imaging (MRI) equipment as magnetic fields may adversely affect the operation of the pump. Remove the pump from the patient during MRI procedures and keep it at a safe distance from magnetic energy. • Do not use the pump near ECG equipment as the pump may interfere with the operation of the equipment. Monitor ECG equipment carefully when using this pump. 1

2 CADD-Legacy™ Pump

Delivery Modes The CADD-Legacy™ ambulatory drug delivery pump provides measured drug therapy to patients in hospital or outpatient settings. The CADD-Legacy™ pump is indicated for intravenous, intra-arterial, subcutaneous, intraperitoneal, epidural space, or subarachnoid space infusion.

Dosage

Epidural administration is limited to use with indwelling catheters for short term delivery of anesthetics and short or long term delivery of analgesics. Subarachnoid administration is limited to use with indwelling catheters for short-term delivery of analgesics. Clinician Bolus (used here as a loading dose) Demand Doses

Continuous Rate

The CADD-Legacy™ PCA pump may be programmed to deliver medication in one of three ways: 1) continuous rate only, 2) patient-activated dose only and 3) continuous rate and patientactivated dose. (See figure 1.) The CADD-Legacy™ PLUS pump may be programmed to deliver in one of two modes: (1) Continuous, (2) Intermittent . (See figures 2 and 3.) The CADD-Legacy™ 1 pump operates in continuous mode. (See figure 2.) Figure 4 shows a diagram of the CADD-Legacy™ pump.

PCA Delivery Profile The PCA (patient-controlled analgesia) delivery mode is used for therapies that require a continuous rate of infusion, patient-controlled demand doses, or both, such as patientcontrolled analgesia.

Time

Figure 1. PCA mode delivery profile.

Continuous Mode Delivery Profile The Continuous delivery mode allows the infusion of drug at a constant, programmed rate.

Delivery Rate CADD-Legacy™ PLUS (ML/HR) or CADD-Legacy™ 1 (ML/24 HR)

Time Continuous Delivery

Figure 2. Continuous mode delivery profile.

Dose Cycle Dose Volume

Dose Starts in

Dose

Dose

Duration

Duration

Time Intermittent Delivery

Figure 3. Intermittent mode delivery profile.

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Intermittent Mode Delivery Profile The Intermittent delivery mode allows the infusion of a specific volume of drug at regular programmed intervals.

Threaded Mounting Hole

Display Power Jack

Power Jack symbol

Accessory Jack

Accessory Jack Symbol

AC Indicator Light Battery Compartment Air Detector ®

Cassette Lock Keypad

Dose Key on CADD-Legacy™ PCA

Front View

Cassette CADD-Legacy™ PCA Cassette Lock

Rear View

Figure 4. Front and Rear views of the CADD-Legacy™ Pump. Features are identical on all CADD-Legacy™ pumps except as illustrated for the CADD-Legacy™ PCA pump.

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PCA Delivery Mode Scroll Ranges Units

Starting

Increment

ML

0.10

All values:

0.10

50.00

MG

10% of Concentration

Values between 0.01 and 0.5: Values between 0.50 and 100.0: Values between 100.0 and 1000.0: Values greater than 1000.0:

0.01 0.10 1.00 10.0

Concentration x 50

10% of Concentration

Values between 0.1 and 100: Values between 100 and 1000: Values greater than 1000:

0.10 1.00 10.00

Concentration x 50

MCG

Maximum

Table 1. PCA delivery mode: continuous rate scroll ranges. Milligrams Concentration Demand Dose Clinician Bolus mg/ml increment max. increment max.

Micrograms Concentration Demand Dose Clinician Bolus mcg/ml increment max. increment max.

0.1 0.2 0.3 0.4 0.5 1 2 3 4 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

1 2 3 4 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 200 300 400 500

0.01 0.02 0.03 0.04 0.05 0.05 0.10 0.15 0.20 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00

0.99 1.98 2.97 3.96 4.95 9.9 19.8 29.7 39.6 49.5 99.0 148.5 198.0 247.5 297.0 346.5 396.0 445.5 495.0 544.5 594.0 643.5 693.0 742.5 792.0 841.5 891.0 940.5 990.0

0.01 0.02 0.03 0.04 0.05 0.05 0.10 0.15 0.20 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00

2 4 6 8 10 20 40 60 80 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Table 2. Demand dose, clinician bolus scroll ranges, milligrams

0.05 0.10 0.15 0.20 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 10.00 15.00 20.00 25.00

9.9 19.8 29.7 39.6 49.5 99.0 148.5 198.0 247.5 297.0 346.5 396.0 445.5 495.0 544.5 594.0 643.5 693.0 742.5 792.0 841.5 891.0 940.5 990.0 1980.0 2970.0 3960.0 4950.0

20 40 60 80 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 4000 6000 8000 10000

Table 3. Demand dose, clinician bolus scroll ranges, micrograms Milliliters Demand Dose increment max. 0.05

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0.05 0.10 0.15 0.20 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 3.25 3.50 3.75 4.00 4.25 4.50 4.75 5.00 10.00 15.00 20.00 25.00

9.9

Clinician Bolus increment max. 0.05

20

Table 4. Demand dose, clinician bolus scroll ranges, milliliters

Specifications (Nominal)

High Pressure Alarm 26 (±14) psi, 1.79 (± 0.97) bar

General Pump Specifications

Air Detector Alarm Single bubble Low sensitivity = greater than 0.250 ml High sensitivity = greater than 0.100 ml Multi-bubble = 1.0 ml nominal

Resolution Medication Cassette™ Reservoir or CADD® Administration Set, 0.050 ml/pump stroke nominal Size 4.1 cm x 9.5 cm x 11.2 cm (1.6 in. x 3.8 in. x 4.4 in.) excluding cassette or other accessories Weight 391 g (13.8 oz.) including 2 AA batteries, empty 100-ml Medication Cassette™ Reservoir, and air detector, excluding other accessories Pump Alarms Low battery power; depleted battery power; battery dislodged; pump stopped; pump fault; low reservoir volume; high delivery pressure; air in line; disposable not attached when run attempted; motor locked; upstream occlusion; reservoir volume empty; program incomplete; remote dose cord removed; key stuck; disposable detached, power removed, value not saved. Bolus Volume at Occlusion Alarm Pressure 0.050 ml resolution sets/reservoirs: < 0.15 ml Power Sources Two AA alkaline batteries such as DURACELL® or EVEREADY Energizer®; AC adapter. An internal battery powers the clock. When it is depleted, it cannot reliably maintain the clock time. This battery must be replaced by SIMS Deltec, Inc. The internal battery has an expected life of 5 years. System Operating Temperature* +2°C to 40°C (35°F to 104°F) System Storage Temperature* -20°C to 60°C (-4°F to 140°F) System Delivery Accuracy* ± 6% (nominal)

Delivery Mode Specifications CADD-Legacy™ PCA pump Reservoir Volume 1 to 9999 or Not In Use; programmable in 1 ml increments, displayed in 0.1 ml increments Default: 1 ml Units Milliliters (ml), milligrams (mg), micrograms (mcg) Default: milligrams Concentration Mg/ml: 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 10, 15, ... 95, 100 (Default: 100 mg/ml) Mcg/ml: 1, 2, 3, 4, 5, 10, 15, ...95, 100, 200, 300, 400, 500 (Default: 500 mcg/ml) Continuous Rate 0 to 50 ml/hr (or the mg or mcg equivalent) (See Table 1 for scroll ranges) Demand Dose 0 to 9.9 ml in 0.05 ml increments (or the mg or mcg equivalent) (See Tables 2 and 3 for scroll ranges) Delivery rate (Continuous Rate + Demand Dose): 125 ml/hr nominal Dose Lockout 5 minutes to 24 hours in the following increments: 1 minute for values between 5 and 20 minutes 5 minutes between 20 minutes and 24 hours Default: 24 hours Doses Per Hour 1 to 12 doses in 1 dose increments (will also be limited by the Demand Dose Lockout value) Default: 1 dose/hr

*System is defined as a CADD-Legacy™ pump with an attached Medication Cassette™ Reservoir and CADD® Extension Set with integral anti-siphon valve, or an attached CADD® Administration Set with integral or add-on anti-siphon valve.

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Doses Given 0 to 999 Doses Attempted 0 to 999 Given 0 to 99999.95 in 0.05 unit increments or 0 to 99999.99 in 0.01 unit increments (increments converted to current units based on concentration)

5 minutes from 00:10 to 24:00 Default: 30 minutes Dose Cycle 10 minutes to 96 hours in 5 minute increments Default: 4 hours KVO Rate 0 to 125.0 ml/hr in increments of 0.1 ml/hr Default: 0 ml/hr

Clinician Bolus 0.05 ml to 20.00 ml (or mg or mcg equivalent) (See Tables 1, 2 and 3 for scroll ranges) Delivery rate (Continuous Rate + Clinician Bolus): 125 ml/hr nominal

Dose Starts in Immediate or 1 minute to 96 hours in the following increments: 00:01 from 00:00 to 00:10 00:05 from 00:10 to 96:00 Default: Immediate

CADD-Legacy™ 1 pump

Continuous Delivery Mode Specifications

Continuous Delivery Mode Specifications

Reservoir Volume 1 to 9999 or Not In Use; programmable in 1 ml increments, displayed in 0.1 ml increments Default: 1 ml

Reservoir Volume 1 to 9999 or Not In Use; programmable in 1 ml increments, displayed in 0.1 ml increments Default: 1 ml Continuous Rate 1 to 3000 ml/24 hr in increments of 1 ml/24hr Default: 0 ml/24hr Given 0 to 99999.95 in 0.05 ml increments CADD-Legacy™ PLUS pump Intermittent Delivery Mode Specifications Reservoir Volume 1 to 9999 or Not In Use; programmable in 1 ml increments, displayed in 0.1 ml increments Default: 1 ml Dose Volume 0.1 to 1000.0 ml in increments of 0.1 Default: 0.0 ml Dose Duration 1 minute to 24 hours in the following increments: 1 minute from 00:01 to 00:10

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Continuous Rate 0.1 ml/hr to 125.0 ml/hr in increments of 0.1 ml/hr Default: 0.0 ml/hr Given 0 to 99999.95 in 0.05 ml increments

Biomed Functions Specifications Air Detector Status: Off On- low On- high Default: On-high Upstream Occlusion Status: Off On Default: On Delivery Mode (CADD-Legacy™ PLUS only): Continuous Intermittent Default: Intermittent

Compatible Medication Cassette™ Reservoirs and CADD® Administration Sets • 50-ml or 100-ml Medication Cassette™ Reservoir, used with the CADD® Extension Set with Anti-siphon Valve. • CADD® Administration Set with integral anti-siphon valve, with or without bag spike (allows use of flexible plastic bag or sterile vial with injector) • CADD® Administration Set with add-on anti-siphon valve and bag spike (allows for gravity priming before attaching the add on anti-siphon valve)

Remote Dose Cord Deltec provides a Remote Dose Cord for the CADD-Legacy™ PCA pump which is an extension of the Í key. The push button is a Single Pole Double Throw (SPDT) switch which operates in the same manner as the Í key. When the Remote Dose Cord is attached to the pump, the patient may press either the Remote Dose button or the Í key to receive a Demand Dose. The clinician may also use either the Remote Dose button or the Í key to deliver a clinician-activated bolus. For easy access, the Remote Dose Cord may be fastened to the patient’s clothing or bedsheet with the attached clip. There is an alarm/function present in the CADD-Legacy™ PCA pump. If the Remote Dose Cord is removed, the display shows a message “Remote Dose Removed”. The pump sounds an audible alarm until the „ key is pressed to acknowledge the alarm. NOTE: To detach the Remote Dose Cord from the pump, grasp the Remote Dose Cord connector and pull back using a straight, steady motion.

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3 Batteries

Battery Compatibility Recommended Batteries Two AA alkaline batteries are recommended for use in the CADD-Legacy™ pumps. Carbonzinc, mercury, nickel-cadmium, nickel-metalhydride, or zinc-air AA batteries should not be used. Battery Life The CADD-Legacy™ pumps have been designed to provide optimal battery life. The expected battery life in the CADD-Legacy™ pumps depends on the following factors:

Recommended storage conditions are 10°C to 25°C (50°F to 77°F) with no more than 65% relative humidity noncondensing. The following table may be used to predict typical alkaline battery life at different delivery rates when alkaline batteries are used in the CADD-Legacy™ pump. As expected, battery life decreases as the delivery rate increases. This table is based on laboratory tests using fresh DURACELL® alkaline batteries in CADD-Legacy™ pumps while the pumps were operating at room temperature. Actual battery life may be significantly shorter depending on the operating temperature and the storage conditions of the battery.

• Programmed delivery rate • Operating temperatures • Battery type and brand • Battery age

DURACELL® Alkaline Battery Life Battery life is shortened significantly at very low operating temperatures. For example, at 0°C (32°F), an alkaline battery will yield approximately 30% of its normal capacity. Alkaline batteries do not need to be stored in a refrigerator. After four years of storage at 21°C (70°F), an alkaline battery retains approximately 86% of its original capacity. Battery life will be shorter if the battery is stored above room temperature. An alkaline battery stored at 43°C (110°F) will be down to approximately 80% of its capacity within one year.

Continuous Delivery Battery Life with Alkaline Batteries Rate

Life

Volume

0.4 ml/hr 4 ml/hr 10 ml/hr 15 ml/hr 30 ml/hr 75 ml/hr 125 ml/hr

338 hrs 178 hrs 112 hrs 96 hrs 53 hrs 18 hrs 15 hrs

135 ml 712 ml 1120 ml 1440 ml 1590 ml 1350 ml 1875 ml

Table 5. Two AA Alkaline-type batteries used with the CADD-Legacy™ pumps.

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Intermittent Delivery Battery Life with Alkaline Batteries Dose Volume

Duration

Dose Cycle

KVO

Life

Volume

23.5 ml 61 ml 125 ml

1:00 hr 1:00 hr 1:00 hr

5:00 hr 6:00 hr 6:00 hr

0.2 ml/hr 0.2 ml/hr 0.2 ml/hr

193 hr 120 hr 65 hr

915 ml 1224 ml 1356 ml

Table 6. Two AA Alkaline-type batteries used with the CADD-Legacy™ pumps.

135 120

Rate (ml/hr)

105 90 75 60 45 30 15 0

10

20

30

40

50 Hours

60

70

80

90

100

Figure 5. Operating time to low battery alarm using alkaline batteries.

18 16

Rate (ml/hr)

14 12 10 8 6 4 2 0

50

100

150

200

250

300

350

Hours Figure 6. Operating time to low battery alarm using alkaline batteries.

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Continuous Delivery Battery Life with Lithium Batteries Rate

Life

Volume

0.4 ml/hr 4 ml/hr 10 ml/hr 15 ml/hr 30 ml/hr 75 ml/hr 125 ml/hr

413 hrs 307 hrs 190 hrs 163 hrs 90 hrs 33 hrs 22 hrs

165 ml 1228 ml 1900 ml 2445 ml 2700 ml 2475 ml 2750 ml

Table 7. Two AA Lithium-type batteries used with the CADD-Legacy™ pumps.

Intermittent Delivery Battery Life with Lithium Batteries Dose Volume

Duration

Dose Cycle

KVO

Life

Volume

23.5 ml 61 ml 125 ml

1:00 hr 1:00 hr 1:00 hr

5:00 hr 6:00 hr 6:00 hr

0.2 ml/hr 0.2 ml/hr 0.2 ml/hr

300 hrs 185 hrs 125 hrs

1458 ml 1911 ml 2625 ml

Table 8. Two AA Lithium-type batteries used with the CADD-Legacy™ pumps.

135 120

Rate (ml/hr)

105 90 75 60 45 30 15 0

20

40

60

80

100 Hours

120

250

300

140

160

180

200

Figure 7. Dual-stroke operating time on lithium batteries.

18 16

Rate (ml/hr)

14 12 10 8 6 4 2 0

50

100

150

200

Hours Figure 8. Single-stroke operating time on lithium batteries.

10

350

400

450

4 Construction

The pump’s housing is made of a special high impact plastic. It is composed of two sections: the rear and front housing. The pump housing is sealed to ensure that the pump is water resistant. The battery compartment is not water resistant. NOTE: The CADD-Legacy™ ambulatory infusion pump is water resistant, but not waterproof. The pump is “Splashproof” and is characterized by the IEC code of IPX4. The battery compartment is accessed through a removable door on the rear housing. Within the battery compartment is space for the batteries and the four battery contacts. ™

On CADD-Legacy pumps the Medication Cassette™ Reservoir or the administration set is attached to the bottom of the pump by inserting the two hooks on the cassette into the mating hinge pins on the pump. The pump and the reservoir or the administration set are then placed in an upright position on a firm, flat surface. The reservoir or the administration set must be secured in place by inserting a coin (or key if using the CADD-Legacy™ PCA pump) in the slot on the pump’s locking button, pushing the button in and turning the button onequarter turn counter-clockwise. NOTE: The Medication Cassette™ Reservoir and the administration set are intended for single use only. The keyboard, located on the front housing, is composed of eight membrane switches (nine membrane switches on the CADD-Legacy™ PCA pump) and is sealed against moisture. All of the keys contain domes to provide a tactile feel when the key is pressed. The keyboard keys are sensed by the pump’s microprocessor.

The Liquid Crystal Display (LCD), also located on the front housing, shows the pump status and programmed settings. The dot matrix display consists of 16 character columns with 2 rows of characters, and is selected by the pump’s microprocessor according to status conditions and keyboard entries. The microprocessor and other circuitry which control the pump are located on a printed circuit board. The board contains the Central Processing Unit (CPU), motor driver circuitry, and other circuitry. The circuitry is designed to reduce susceptibility to interference from electromagnetic fields and to dissipate electrostatic discharge. The LCD controller is mounted on the LCD using chip on glass technology. The pumping mechanism subassembly contains the motor, gear train, camshaft, valves, expulsor, sensing disk, infrared light source, infrared detector, occlusion sensors, disposable sensor, and cassette locking button. Via the motor driver circuitry, the pump’s microprocessor controls motor rotation. Two external port connectors are utilized for remote dose and external power input. The accessory jack is used for attachment of the Remote Dose Cord (CADD-Legacy™ PCA pump only) and interface cable. The Remote Dose Cord enables the patient to use either of two options to begin a Demand Dose when using the PCA delivery mode: (1) the Remote Dose button; or (2) the Í key. The second port allows connection to an AC adapter. The keyboard is connected to the printed circuit board via a flex circuit tail. Discrete wires connect the pumping mechanism, motor, and sensors to the printed circuit board. The accessory jack in conjunction with the interface cable allows download of events using the CADD-DIPLOMAT™ software.

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5 Theory of Operation

Keyboard Circuitry ™

The CADD-Legacy pumps are controlled by a microprocessor. The actions of the microprocessor are controlled by a program, which is contained in the memory. Commands are issued to the microprocessor from the user via the eight keys on the keyboard (nine keys and Remote Dose Cord on CADD-Legacy™ PCA pump). The keys on the keyboard are arranged in a 3x3 matrix which feeds into the keyboard encoder. A key closure applies a ground to the associated input of the keyboard encoder. Key debounce circuitry resident in the keyboard encoder provides a clean output signal to the microprocessor for the duration of the key closure. The microprocessor reads keyboard status by accessing special memory locations in the keyboard encoder. The Remote Dose Cord button (CADD-Legacy™ PCA pump only) consists of an SPDT switch with one switch output going to the microprocessor and the other going to the keyboard encoder. The switch has a common input line and two output signal lines. The two signal lines are complementary such that one line is always logic high and the other is always low. When the Remote Dose Cord button is pressed, both signal lines change to the alternate logic state. This redundancy prevents a single line failure from starting a dose delivery. The Å button allows the pump to be placed in a very low power mode by turning off all sensors and LCD, but some battery energy is still used by the electronics. To maximize battery life, remove the batteries when pump is not in use.

Data Memory in Real Time Clock RAM Many settings of the pump’s delivery and record-keeping parameters are stored by the microprocessor in a Battery backed RAM in the Real Time Clock. Data to and from the memory is presented serially. Whenever the microprocessor uses data from the Real Time Clock, the data is checked for validity.

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EEPROM Data describing the current delivery protocol is stored in an EEPROM included in the microprocessor. Whenever this data is used, it is checked for validity.

Battery Backed RAM Additional settings of the pump’s delivery and record keeping parameters are stored in a battery backed Random Access Memory (RAM). Battery backup is provided by a printed circuit board-mounted lithium battery. This battery provides a minimum of five years of memory retention during normal pump usage. Whenever the microprocessor uses data from the RAM, the data is checked for validity.

Time Base Circuitry An accurate 3.6864 MHz timebase is provided by a quartz crystal. The 3.6864 MHz signal is connected to the microprocessor, where it is frequency-divided to access the program memory at a cycle rate of 921 kHz. In addition, an accurate 32.768 kHz timebase is provided by a second quartz crystal. The 32.768 kHz signal is used for the real time clock.

LCD Circuitry The CADD-Legacy™ pumps feature a 2 line by 16 character Liquid Crystal Display (LCD). The characters on this dot matrix display are formed by a matrix of 5 by 7 dots. It is reflective only, with a black on silver appearance, with no backlight. The display includes a controller chip mounted directly on the glass capable of interfacing with 4 and 8 bit systems to display 92 kinds of characters, numerals, symbols, and special characters under control of a built in character generator ROM. A RAM is also included to make other special characters possible.

LED Indicator

Watchdog Timer Circuit

A green Light Emitting Diode (LED) is provided under the pump’s front panel overlay to provide pump power status to the user. When this LED is lit, it indicates that an AC adapter is being used to power the pump.

Watchdog timer circuitry is provided to monitor the status of the microprocessor. If the microprocessor fails to function properly, the watchdog circuit issues a reset signal which disables the motor and enables the audible alarm. To assure proper function, the microprocessor must strobe the watchdog circuit at least once every second in order to prevent the watchdog from performing its reset function.

Flash PROM Technology Program memory for the pump is stored in Flash Programmable Read Only Memory (Flash PROM). This type of memory allows modification of the contents without physically removing the device from the circuit board. Under certain circumstances the program can also be downloaded. Several layers of redundancy in the programming system prevent accidental erasing or modification of the PROM.

Audible Alarm Circuitry

The reset output from the watchdog circuit is a pulse output. This acts to “jump start” the microprocessor. This unique feature allows the microprocessor to test the watchdog circuit on every power-up. By setting a flag in memory and not strobing the watchdog, the microprocessor can force a watchdog time-out. After being reset, the microprocessor checks the status flag to see if this was a time-out test. If so, the microprocessor verifies the watchdog’s ability to disable the motor and then continues normal power-up activities.

Audible alarm circuitry consists of two piezo electric disks and an independent oscillator. The disks flex or bend in resonance with the output of the oscillator. The piezo disks are mounted to the pump housing to enhance sound level.

If a reset occurs when the microprocessor is not expecting it, the microprocessor traps the event, sounds the audible alarm and displays an error message on the LCD.

The microprocessor controls the audible alarm by selecting the alarm control line for more than 0.5 seconds. The oscillator which drives the piezo disks is capable of providing two driving frequencies. The low frequency is in the range of 700 to 1500 Hz and the high frequency is in the range of 1600 to 2500 Hz. When the microprocessor selects the audible alarm, the alarm enters a warble mode where it oscillates between the low and high frequency sound at a rate of 0.8 and 2 Hz.

Motor Drive/Motor Watchdog Circuit

Low battery voltage detection and watchdog timer circuitry also have the ability to enable the audible alarm via the microprocessor. The audible alarm circuitry is backed up by a super capacitor. The super capacitor provides energy for the alarm in the instance where all power is lost while pump is in the RUN mode. There is enough energy in the super capacitor to drive the audible alarm for 3 minutes when the pump has been in the RUN mode for 2 minutes or longer.

The motor drive circuitry is composed of a series of power FET transistors, passive components, and two voltage comparators. Built into the motor drive circuitry is an RC timer which times how long the motor runs each time it is turned on. If the motor runs for more than an average of 4 seconds, the circuit will time out and disable the motor. A unique feature of this circuit is that control lines to and from the microprocessor circuit allow the microprocessor to perform a complete functional test of the motor drive circuit without running the motor. The microprocessor performs this test function every several minutes to assure its continued functionality. An input from the watchdog circuit prevents motor operation if the watchdog timer expires. Rotation of the motor is sensed by the microprocessor via an infrared-sensitive photo detector. An infrared light source is mounted

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so that its light beam illuminates the infrared detector. An opaque flag is mounted concentrically to the camshaft and rotates with it between the infrared light source and detector. When the flag interrupts the light beam, the output of the detector is sensed by the microprocessor via an input port bit. Power to the infrared LED light source is controlled by the motor drive circuit and is off when the motor is not running to conserve battery life. In the microprocessor software, multiple checks are made on motion of the camshaft. When the motor is commanded to start, the infrared sensor must show that half a revolution has occurred within four seconds and that the motor has stopped when half a rotation was completed. In addition, no camshaft rotation can take place when the motor has not been commanded to run.

Power Circuitry Power for the pump is normally supplied by two AA alkaline batteries, two AA lithium batteries, or an AC adapter. These types of batteries have a fairly low internal resistance over their discharge range, which will keep power supply noise low. Other types of batteries, such as carbon-zinc, exhibit high internal resistance, especially near depletion. A voltage drop across the internal resistance occurs when current is drawn by the motor during pump activations. This current is demanded in short pulses when the motor is first turned on and

generates large spikes in the battery voltage. This noise can cause the low battery detection circuit to shut down the pump. The power from the two AA batteries is boosted to +5VDC. This 5V is used to power the motor and a 3.3V linear regulator. The linear regulator provides power to all the other circuitry including the microprocessor.

Voltage Reference Circuit A voltage reference circuit provides a constant DC voltage to the microprocessor Analog to Digital Converter (ADC). By reading this input and comparing the value to a predetermined range, the microprocessor can validate the accuracy of the 3.3-volt power supply. Variations in the 3.3-volt supply left undetected can result in inaccuracy in the low battery alarm set points and variations in other calculated values. (Also refer to Voltage Detector Circuit description on page 18.)

Pumping Mechanism The pumping mechanism is linear peristaltic with two active valves and an expulsor. Pumping occurs when the expulsor presses on the reservoir pump tubing in sequence with the inlet and outlet valves. At rest, the outlet valve is pressing down fully on the tubing and the expulsor and inlet valve are retracted. (See Figure 9.) Motor

Camshaft

Pump Housing Expulsor Occlusion Sensor

Lock Cassette

Cassette Hinge Pump Tubing

Figure 9. A simulated pumping mechanism in a CADD-Legacy™ pump.

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Upstream Sensor Pressure Plate Inlet Valve Outlet Valve

When the microprocessor commands the mechanism to pump, the camshaft begins to rotate, thus controlling the following pump cycle: 1. The inlet valve closes. 2. In synchrony with the expulsor moving down to compress the tubing, the outlet valve opens, expelling 0.050 ml of fluid toward the patient. 3. The outlet valve closes. 4. The inlet valve opens as the expulsor is retracted, causing fluid from the reservoir to again fill the pump tubing segment. 5. The camshaft rotation stops after half a revolution and the cycle is completed.

The microprocessor uses its timer circuits to accurately time the 18 seconds (in this example) between mechanism activations. The timebase accuracy is ultimately determined by the 3.6864 MHz quartz crystal oscillator.

Air Detector The air detector is designed to detect air in the outlet tubing fluid path. The air detector can be set to On-high sensitivity, On-low sensitivity, or Off by accessing Biomed Functions. When the On-high sensitivity setting is selected the pump will detect a single bubble greater than 0.100 ml. When the On-low sensitivity setting is selected the pump will detect a single bubble greater than 0.250 ml.

Pumping Characteristics

Multi-bubble Sensing

To deliver the amount of drug specified by the parameter settings, the pump’s microprocessor causes the pump mechanism to deliver fluid “pulses” timed according to the desired rate. At rates of 15 ml/hr or less the microprocessor delivers a single pulse to the motor circuit causing a half revolution of the camshaft and fluid delivery in 0.05 ml increments. At rates greater than 15 ml/hr the microprocessor delivers two back to back pulses to the motor circuit causing a full revolution of the camshaft and fluid delivery in 0.1 ml increments. Thus, to deliver 20 ml/hr, for example, the microprocessor solves these equations:

The air detector is also designed to sense if an accumulation of more than 1 ml of air has passed through the outlet tubing path in the last 15 minutes. This feature is active anytime the air detector is on.

Mechanism activations per hr = 20 ml per hr/0.1 ml per activation = 20/0.1 = 200 Time (seconds) between activations = 3600 sec per hr/number of activations per hr = 3600/200 = 18 NOTE: At rates 15 ≤ ml/hr the pump delivers 0.05 ml per stroke. This allows a more continuous delivery at low rates.

The air detector is compatible with all of the Medication Cassette™ Reservoirs and CADD® Administration Sets indicated for use with the CADD-Legacy™ pump, and all pump accessories. It is powered directly from the pump and no additional power is required.

Theory of Operation The air detector consists of sensor electronics and two ultrasonic transducers positioned on opposite sides of the fluid path. One transducer acts as an acoustic transmitter and the other as an acoustic receiver. Air detection occurs when air in the fluid path causes a reduction in the signal level to the receiver. When the signal is interrupted for a preset length of time, the sensing circuitry sends a signal to the microprocessor indicating air in the fluid path. To maximize the reliability of the system and to reduce false alarms, the transmitted signal is swept over a frequency range. This accommodates varying resonance frequencies of the transducer and reduces sensitivity to tubing tolerances and other mechanical variations.

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Downstream Occlusion Sensor The downstream occlusion sensor is designed to detect excessive pressure in the outlet tubing. If the fluid path to the patient becomes blocked, the pump tubing will expand as pumping occurs. When there has been an amount of inflation corresponding to 179.3 kPa ± 96.5 kPa, 1.79 (± 0.97) bar, or 26 (±14) psi, the occlusion sensor trips, whereupon the microprocessor stops the pump mechanism and issues visual and audible alarms. Thus the maximum pressure which can be developed is 276 kPa (2.76 bar, 40 psi).

Construction The downstream occlusion sensor consists of a membrane switch located on the bottom of the pump next to the outlet valve. The switch is fastened to the housing with an adhesive to ensure that the overall assembly is water resistant.

Theory of Operation The membrane switch is in contact with the outlet tubing when a cassette is installed. Tubing expansion caused by a downstream occlusion results in closure of the membrane switch. Switch closure sends a logic low to the microprocessor indicating a downstream occlusion.

Upstream Occlusion Sensor The upstream occlusion sensor detects an occlusion in the inlet tubing which would prevent or restrict the flow of fluid to the pump.

Construction The upstream occlusion sensor consists of a strain gauge sensor located on the bottom of the pump next to the inlet valve. The sensor is fastened to the housing with an adhesive to ensure that the overall assembly is water resistant.

Theory of Operation When a cassette is installed on the pump, the inlet tubing is in contact with the sensor. In order to conserve battery power, the upstream occlusion sensor circuit is only activated while the motor circuitry is enabled. Pressure on the sensor is read just prior to the motor starting and after the end of the motor stroke. The microprocessor uses an average of the pressure exerted by the unoccluded tubing to establish a baseline pressure. If the tubing pressure at the end of a motor stroke is below the baseline pressure, the upstream tubing is occluded.

Cassette Attachment Detection The pump uses the upstream occlusion sensor and cassette present sensor to verify the presence of a cassette. If an infusion is started by pressing ⁄ when there is no cassette installed or if a cassette is improperly seated, the pump will initiate a visual and audible alarm.

Theory of Operation During manufacture of the pump, upstream occlusion sensor readings are recorded for no cassette installed and typical cassette installed. These readings are used to calculate threshold levels for cassette detection. When a cassette is first attached to the pump, the new sensor reading must be above the calculated threshold level. Additional readings are taken periodically while the pump is in use. If the sensor readings drop below the threshold when the motor is off, or the cassette present sensor circuit does not sense the presence of a cassette, the cassette is considered removed.

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6 Safety Features and Fault Detection microprocessor can force a watchdog time-out. After being reset, the microprocessor checks the status flag to see if this was a time-out test. If so, the microprocessor verifies the watchdog’s ability to disable the motor and then continues normal power-up activities. If the reset occurred when the microprocessor was not expecting it, the microprocessor traps the event, sounds the audible alarm and displays an error message on the LCD.

Hardware Safety Features Key hardware safety features include a watchdog timer circuit, motor drive and motor watchdog circuits, cassette present sensor circuit, and a voltage detector circuit. Each safety circuit performs a unique function to insure the overall safety of the device. (See Figure 10.)

Watchdog Timer Circuit

Motor Drive/Motor Watchdog Circuit

The microprocessor must send an appropriate signal to the watchdog circuit at least once per second. If the microprocessor does not, the watchdog circuit will time out and shut down the pump controller.

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REAL-TIME CLOCK

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WATCHDOG

KEYBOARD

MOTOR WATCHDOG

POWER INPUT

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CPU/IO

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MOTOR DRIVE

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DATA MEMORY

VOLTAGE MONITOR

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LCD DISPLAY PROGRAM MEMORY

AUDIBLE ALARM

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Watchdog timer circuitry is provided to monitor the status of the microprocessor and disable the motor and enable the audible alarm if the microprocessor fails to function properly. The microprocessor must strobe the watchdog circuit at least once every second in order to prevent the watchdog from performing its reset function. The reset output from watchdog circuit is a pulse output. This acts to “jump start” the microprocessor. This unique feature allows the microprocessor to test the watchdog circuit on every power-up. By setting a flag in memory and not strobing the watchdog, the

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Motor drive circuitry is composed of a series of power FET transistors, passive components, and two voltage comparators. Built into the motor drive circuitry is an RC timer which times how long the motor runs each time it is turned on. If the motor runs for more than an average of 4 seconds, the circuit will time out and disable the motor. A unique feature of this circuit is that control lines from the microprocessor can perform a complete functional test of the motor drive circuit without running the motor. The microprocessor performs this test function every several minutes to assure its continued functionality. An input from the watchdog circuit prevents motor operation if the watchdog timer expires.

SENSORS

Figure 10. CADD-Legacy™ pump hardware block diagram.

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