Addendum
38 Pages
Preview
Page 1
1 Capnography (ETCO2) Operator’s Manual Addendum 1.1
Overview This addendum describes the operation of the Capnography option for the Puritan Bennett™ 980 Series Ventilator. The Capnography option monitors end-tidal carbon dioxide levels (ETCO2) only. The capnography sensor uses infrared absorption spectroscopy to measure mainstream ETCO2 while avoiding contamination with patient secretions.
1.2
Product Description The Capnography option must be used with either of the following components: •
ETCO2 airway adapter (for ETCO2 monitoring only). This adapter is available in neonatal/pediatric and pediatric/adult configurations, and in reusable or disposable versions.
•
Flow and CO2 combination sensor (for use with neonatal patients, only). This component combines both a proximal flow transducer and an ETCO2 built-in adapter. This sensor can be used when both NeoMode 2.0 and Capnography options are installed. This sensor is for single-use only.
The flow sensing component of the flow and CO2 combination sensor is not required to be used during ETCO2 monitoring. If the flow and CO2 combination sensor is used for ETCO2 monitoring only, the sensor must be connected to the ventilator’s front panel in the location labeled Prox, and the Proximal Flow option disabled.This combination sensor can be used when the Proximal Flow System option is also in use so that flow sensing and ETCO2 monitoring can both occur simultaneously. More information regarding the Proximal Flow System is available in the Proximal Flow Option Appendix and NeoMode 2.0 details are described in the NeoMode 2.0 Appendix in this manual. For general parameter and ventilator setup information Reference Chapter 4 in this manual. 1.3
Intended Use The Capnography option is used for measuring the partial pressure of carbon dioxide in the exhaled gas of invasively ventilated, neonatal, pediatric, and adult patients at the breathing circuit wye.
1-1
Capnography (ETCO2)
1.4
Safety Symbol Definitions This section contains safety information for users who should always exercise appropriate caution while using the ventilator. Table 1-1. Safety Symbol Definitions Symbol
Definition WARNING Warnings alert users to potential serious outcomes (death, injury, or adverse events) to the patient, user, or environment. Caution Cautions alert users to exercise appropriate care for safe and effective use of the product. Note Notes provide additional guidelines or information.
1.5
1-2
Safety Information WARNING: The Puritan Bennett™ 980 series ventilator contains phthalates. When used as indicated, very limited exposure to trace amounts of phthalates may occur. There is no clear clinical evidence that this degree of exposure increases clinical risk. However, in order to minimize risk of phthalate exposure in children and nursing or pregnant women, this product should only be used as directed. WARNING: The ventilator offers a variety of breath delivery options. Throughout the patient’s treatment, the clinician should carefully select the ventilation mode and settings to use for that patient, based on clinical judgment, considering the condition and needs of the individual patient, as they change from time to time, and considering the benefits, limitations and operating characteristics of each breath delivery option. WARNING: Explosion hazard. Do not use in the presence of flammable anesthetics. WARNING: Follow precautions for electromagnetic interference (EMI) to avoid unreliable ventilator readings.
Operator’s Manual Addendum: Capnography
Safety Information
WARNING: Monitor the CO2 waveform for elevated baseline. An erroneously elevated baseline can be caused by sensor problems. WARNING: If the CO2 waveform appears abnormal, inspect the airway adapters and replace if needed. WARNING: ETCO2 readings are intended only as an adjunct in patient assessment and must be used in conjunction with clinical signs and symptoms. Do not use ETCO2 readings as a basis for changes to ventilator parameters without reference to clinical condition and independent monitors such as blood gas. WARNING: Do not use the flow and CO2 combination sensor if there are kinks in the tubing. WARNING: Prior to patient ventilation, run SST with the exact configuration that will be used on the patient. This includes a patient circuit, airway adapter, and all accessories used with the patient circuit.Reference To run SST in Chapter 3 of this manual. WARNING: Changing ventilator accessories can change the system resistance and compliance. Do not add or remove accessories after running SST. WARNING: Discontinue use if ETCO2 monitoring fails to respond as described. WARNING: The flow and CO2 combination sensor measures gas flow at the patient wye. A system leak, such as that caused by an uncuffed endotracheal tube or a damaged flow and CO2 combination sensor may significantly affect flow-related readings. WARNING: Use only Covidien-branded flow and CO2 combination sensors, capnography sensors, and airway adapters with the Capnography option. Use of other sensors results in an “invalid sensor” message or a “capnography sensor inoperative” alarm and/or erroneous readings. WARNING: To minimize the potential for condensation or secretions clogging the sensor’s pneumatic lines, position the flow and CO2 combination sensor exactly as described in this addendum.
Operator’s Manual Addendum: Capnography
1-3
Capnography (ETCO2)
1-4
WARNING: Do not position the capnography sensor cable or flow and CO2 combination sensor tubing in any manner that may cause entanglement or strangulation. WARNING: To reduce the risk of extubation or disconnection, do not apply tension to or pull on the capnography sensor or flow and CO2 combination sensor tubing. WARNING: To reduce the risk of extubation or breathing circuit disconnection, do not rotate the flow and CO2 combination sensor in the breathing circuit by pulling on the sensor’s tubing. WARNING: The cable management clips supplied with each flow and CO2 combination sensor must be used to mitigate risk of entanglement, kinking, or extubation that could lead to strangulation, hypercarbia, or hypoxemia. WARNING: Do not install the capnography sensor or flow and CO2 combination sensor in the patient circuit if the sensor is not also connected to the BDU. WARNING: Excessive moisture in the flow and CO2 combination sensor tubing may affect the accuracy of the measurements. Periodically check the sensor and tubing for excessive moisture or secretion buildup. WARNING: To avoid the risk of bacterial contamination, clean and sterilize reusable airway adapters per the methods described in this addendum. WARNING: Disposable airway adapters are intended for single use only. Do not re-use these items. These sensors and adapters are not compatible with sterilization techniques. WARNING: Nitrous oxide, elevated levels of oxygen, helium, and halogenated hydrocarbons can influence the CO2 measurement. WARNING: Inspect the airway adapter or flow and CO2 combination sensor prior to use, and do not use if the adapter, sensor body, tubing, or connector are damaged or broken.
Operator’s Manual Addendum: Capnography
Safety Information
Caution: Do not use aerosolized medications when employing CO2 monitoring with either the airway adapter and capnography sensor or the flow and CO2 combination sensor. Increased medication viscosity may contaminate the sensor windows and cause the sensor to fail prematurely. Caution: To prevent damage to cables or pneumatic lines, use the included cable management clips. Caution: Insert sensors in the ventilator circuit with the tubes upright to avoid the effects of excessive moisture. Caution: Ensure all connectors are properly connected, fully engaged, and free from moisture. Caution: To avoid possible damage to the ventilator or sensors, follow standard precautions for electrostatic discharge (ESD). Caution: Clean the reusable airway adapters using only the method and cleaning agents described in this addendum. Note: The flow and CO2 combination sensor, capnography sensor, and airway adapters contain no user serviceable parts. Refer service to qualified service personnel. Note: Dispose of the flow and CO2 combination sensor and disposable airway adapters in accordance with your institution’s protocol. Note: The white-striped tubing of the flow sensor should always be proximal to the patient. Note: Position the flow and CO2 combination sensor with its windows in a vertical, not horizontal position. This helps keep patient secretions from pooling on the windows.
Operator’s Manual Addendum: Capnography
1-5
Capnography (ETCO2)
1.6
Software Requirements Purchased software options must be enabled after the option is purchased using an encrypted access code provided to you or the Customer Service Engineer (CSE). To install software options 1. Enter Service mode. Reference To access Service Mode, in Chapter 3 of this manual. 2.
Touch the options button on the screen that appears.
3.
Touch Installed Options.
4.
Touch Update Options.
5.
Enter the option access code on the virtual keyboard and touch Accept.
6.
Confirm the option is installed by touching Installed Options.
7.
Attach software option label to the installed software options label located at the back of the ventilator.
1.7
Hardware Requirements The following hardware is required:
1.8
•
Option Host Card
•
Capnography sensor (required for ETCO2 measurement)
•
Airway adapter suitable for the particular patient OR
•
Flow and CO2 combination sensor (neonatal circuit only and supports both proximal flow measurement and/or ETCO2 measurement)
End Tidal CO2 Monitoring Description Note: If the current vent type is NIV or vent type changes from INVASIVE to NIV, the Capnography option is automatically disabled.
A capnography sensor is attached to an airway adapter or flow and CO2 combination sensor which is installed at the patient circuit wye to measure end-tidal CO2. The capnography sensor connects to the BDU via a connector located behind the door on the BDU’s front panel. Capnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator, page 1-14. Airway adapters are available in pediatric/adult and neonatal sizes.
1-6
Operator’s Manual Addendum: Capnography
End Tidal CO2 Monitoring Description
When the Option Host card is installed in the ventilator, the card is the communication interface for the capnography system. Data measured by the capnography sensor are displayed on the GUI for monitoring purposes, not for ventilator control. When the ventilator has a capnography sensor installed and enabled, end-tidal CO2 measurements are obtained and displayed on the GUI, and data are updated at the end of each exhalation. CO2 data can be configured as a patient data parameter. If ETCO2 is chosen as a patient data parameter, dashes (- -) appear if the ETCO2 data value is unable to be displayed. The CO2 waveform can be configured as a waveform layout, if desired. Reference To configure the patient data displayed on the GUI and To configure waveforms and loops in Chapter 3 of this manual. The time duration from enabling the ETCO2 monitoring function to achieving specified accuracy is approximately two minutes due to the capnography sensor warm-up process. 1.8.1 ETCO2 Monitoring Components
ETCO2 monitoring components include: Capnography sensor - The capnography sensor connects to the airway adapter or the flow and CO2 combination sensor and contains the optics and electronics for ETCO2 measurement. ETCO2 Airway Adapter - (for ETCO2 monitoring only. This adapter is available in neonatal/pediatric and pediatric/adult configurations, and in reusable or disposable versions. Flow and CO2 Combination Sensor - This sensor and adapter combination is a single-use device which acts as a combination of a Proximal Flow Sensor and an airway adapter (for use with neonatal patients, only). This component combines both a proximal flow transducer and an ETCO2 built-in adapter. This sensor can be used for capnography when both NeoMode 2.0 and Capnography options are installed. This sensor is for single-use only.
Note: Either the airway adapter or Flow and CO2 combination sensor are connected to the capnography sensor for ETCO2 measurement only, or proximal flow and/or ETCO2 measurement, respectively.
Use the airway adapters, flow and CO2 combination sensor, and capnography sensor in the correct combination based upon the patient type and desired monitoring shown in the following tables. Table 1-2. Endotracheal Tube Diameters Item
Endotracheal Tube Inner Diameter (ID), mm
Neonatal/pediatric airway adapters
≤ 4.0
Pediatric/adult airway adapters
≥ 4.5
Neonatal flow and CO2 combination sensor
2.5 to 4.0
Operator’s Manual Addendum: Capnography
1-7
Capnography (ETCO2)
Table 1-3. Items Needed for ETCO2 or Flow/Volume Monitoring Desired Monitoring
Items Needed
Patient Type
Capnography sensor + neonatal/ pediatric airway adapter
Neonatal, pediatric
Capnography sensor + pediatric/ adult airway adapter
Pediatric, adult
Flow and CO2 combination sensor
Neonatal
Proximal flow sensor1
Neonatal
Flow and CO2 combination sensor and capnography sensor
Neonatal
ETCO2
Flow/Volume Only
ETCO2 and Flow/Volume 1.
Reference the Proximal Flow Option Appendix in this manual.
Reference Capnography Monitoring System Part Numbers, page 1-34 to distinguish the components by color. Figure 1-1. Capnography Sensor
1-8
Operator’s Manual Addendum: Capnography
On-screen Symbols
Figure 1-2. ETCO2 Airway Adapters
1
Pediatric/Adult ETCO2 Airway Adapter
2
Neonatal/Pediatric ETCO2 Airway Adapter
Figure 1-3. Flow and CO2 Combination Sensor
1.9
On-screen Symbols When the ETCO2 monitoring function is enabled, measured ETCO2 can be configured to display in the patient data banner.Reference Vital Patient Data in Chapter 3 of this manual for information on configuring the GUI to display various patient data values. When ETCO2 data are questionable or invalid, the data are not displayed.
Operator’s Manual Addendum: Capnography
1-9
Capnography (ETCO2)
Figure 1-4. Sample GUI Screen Showing ETCO2 Data
1
1.10
Patient data banner configured with ETCO2
SST Requirements SST is not required for ETCO2 monitoring only, but in cases where the flow and CO2 combination sensor is used for proximal flow measurement as well as ETCO2 measurement, SST is required. SST must be performed with all circuit components in the configuration to be used on the patient in order for the ventilator to calculate the correct compliance and resistance. Reference To run SST in Chapter 3 of this manual for complete instructions on how to run SST.
Note: For SST, the capnography sensor does not need to be connected to the ventilator, but the Flow and CO2 sensor must connect to the ventilator’s port labeled Prox Flow to avoid leaks.
1.10.1 Attaching the Flow and CO2 Combination Sensor for SST
To attach the flow and CO2 combination sensor to the patient circuit
1-10
1.
Verify the flow and CO2 combination sensor, pneumatic lines and connector are not damaged.
2.
Open the connector panel door and firmly attach the flow and CO2 combination sensor connector to the receptacle in the BDU’s front connector port labeled Prox Flow. ReferenceCapnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator, page 1-14.
Operator’s Manual Addendum: Capnography
SST Requirements
3.
Insert the smaller(15 mm diameter) end (opposite end of UP arrow) of the airway adapter portion of the flow and CO2 combination sensor into the breathing circuit wye, as shown. Reference Attaching Flow and CO2 Combination Sensor or Airway Adapter to Breathing Circuit Wye, page 1-11. Ensure the sensor tubing is in the upward position.
4.
To reposition, grasp the sensor plastic body. Do not rotate it by pulling on the tubing.
5.
Confirm a tight connection.
6.
Space the clips provided evenly to secure the sensor tubing to the breathing circuit.
7.
Zero the adapter if it is new or if prompted by a message displayed on the ventilator’s GUI. Reference Zeroing the Sensor, page 1-15.
8.
Run SST. Reference To run SST in Chapter 3 of this manual.
Note: If using a Heat-Moisture Exchanger (HME) on the endotracheal tube, place the sensor between the HME and the breathing circuit wye. Figure 1-5. Attaching Flow and CO2 Combination Sensor or Airway Adapter to Breathing Circuit Wye
1.10.2 Attaching the airway adapter for SST
To attach the airway adapter for SST 1. Attach the capnography sensor and airway adapter so the small end of the airway adapter connects to the breathing circuit wye. Reference the figure above. The airway adapter attaches the same way as the Flow and CO2 Combination sensor.
Operator’s Manual Addendum: Capnography
1-11
Capnography (ETCO2)
2.
1.11
Run SST. Reference To run SST in Chapter 3 of this manual.
Using the ETCO2 Monitoring function Ensure SST has been run with all accessories installed in the ventilator breathing circuit. Review and follow all warnings prior to patient ventilation with the ETCO2 monitoring function. Reference Safety Information, page 1-2. To connect the capnography sensor to the ventilator 1. Verify the capnography sensor and connector are not damaged in any way. 2.
Open the connector panel door and firmly attach the sensor connector to the receptacle in the BDU’s front connector port labeled CO2.
To attach the ETCO2 airway adapter to the capnography sensor 1.
Use an appropriate ETCO2 airway adapter that matches the patient type (neonatal/pediatric or pediatric/adult) and the patient being ventilated.
2.
Press the capnography sensor onto the ETCO2 airway adapter, oriented so that the smaller end of the adapter can attach to the breathing circuit wye. The capnography sensor will “click” into place when properly seated. Figure 1-6. Connecting the Capnography Sensor to the ETCO2 Airway Adapter
1-12
Operator’s Manual Addendum: Capnography
Using the ETCO2 Monitoring function
To attach the capnography sensor and airway adapter to the patient circuit 1. Attach the capnography sensor and airway adapter so the small end of the airway adapter connects to the breathing circuit wye, and the large end connects to the ET tube. Reference Connecting Breathing Circuit and the ET Tube, page 1-13 for an illustration of the breathing circuit and ET tube connection. The capnography sensor and airway adapter connect the same way as the flow and CO2 combination sensor. Figure 1-7. Connecting Breathing Circuit and the ET Tube
To attach the flow and CO2 combination sensor to the capnography sensor 1.
Snap the flow and CO2 combination sensor into the capnography sensor as shown. Reference Capnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator, page 1-14.
Operator’s Manual Addendum: Capnography
1-13
Capnography (ETCO2)
Figure 1-8. Capnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator
Capnography sensor (connect to BDU port labeled CO2)
5
Breathing circuit wye
2
Patient circuit inspiratory and expiratory limbs
6
HME
3
Flow and CO2 combination sensor (connect to BDU port labeled Prox Flow)
7
Elbow (optional)
4
Cable management clip
8
Endotracheal tube
Note: If using a Heat-Moisture Exchanger (HME) on the endotracheal tube, place the flow and CO2 combination sensor between the HME and the breathing circuit wye. 2.
1-14
1
Ensure the sensor tubing is positioned in an upward direction, as shown in the figure above. If the sensor needs repositioning, DO NOT rotate it by pulling on the tubing. Reposition as follows:
Operator’s Manual Addendum: Capnography
Using the ETCO2 Monitoring function
a.
Grasp the sensor’s plastic body with one hand and the breathing circuit wye with the other hand.
b.
Rotate the sensor body and wye towards each other until the sensor tubing is upright.
c.
Confirm a tight connection between the sensor and breathing circuit wye.
3.
Use cable management clips to attach the sensor tubing to the breathing circuit tubing. Space the clips evenly along the length of the sensor tubing. Twist the ends of each clip to close. Ensure the appropriate clip size is used with the patient circuit in use.
4.
Connect the capnography sensor to the ventilator as described above and shown.
5.
Connect the Flow and CO2 combination sensor to the BDU’s front connector port labeled Prox Flow, as shown. Reference Capnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator, page 1-14.
Note: When the ventilator is set up for Proximal Flow System operation, the flow and CO2 combination sensor can be switched as necessary. There is no need to run SST after switching sensors unless the breathing circuit or other ventilator accessories have been changed.
1.11.1 Zeroing the Sensor
WARNING: If the sensor/adapter assembly zero process is not executed properly, the CO2 waveform information may not be representative of actual exhaled CO2.
If a problem is detected with the CO2 measurement the GUI displays a message stating “CO2 sensor zeroing required” or “Check CO2 sensor adapter.” Zeroing the sensor is typically done when switching between different types of airway adapters. This process corrects for optical differences due to reusable vs. disposable adapters. Before zeroing the sensor 1. Verify the capnography sensor is connected to the port labeled CO2 on the ventilator.
Operator’s Manual Addendum: Capnography
1-15
Capnography (ETCO2)
2.
Connect the capnography sensor to a clean and dry airway adapter or flow and CO2 combination sensor. Reference Connecting the Capnography Sensor to the ETCO2 Airway Adapter, page 1-12 or Capnography Sensor Installation to Flow and CO2 Combination Sensor and Ventilator, page 1-14. Ensure the capnography sensor and airway adapter or flow and CO2 combination sensor is motionless, exposed only to room air, and away from all sources of CO2, including the ventilator, the patient’s breath, and your breath.
To zero the sensor 1. Use the capnography sensor and airway adapter or flow and CO2 combination sensor connected to the ventilator from the previous steps.
1-16
2.
Wait two (2) minutes before proceeding.
3.
At the ventilator setup screen, touch the configure icon. A menu containing tabs appears.
4.
Touch the Options tab. A screen appears containing Installed Options and CO2 tabs.
5.
Touch the CO2 tab.
6.
Follow zeroing setup instructions on the GUI screen.
7.
Touch the Start button to zero the sensor. The length of time to zero the sensor is typically 15 to 20 seconds. During this time, ensure the sensor and adapter is not exposed to any form of CO2.
8.
Verify the message on the screen indicates “CO2 zeroing passed.”
9.
If message reads “Zeroing failed,” ensure all zeroing conditions are met and retest or change adapter.
10.
Place the successfully zeroed sensor assembly in the patient circuit. Reference Attaching Flow and CO2 Combination Sensor or Airway Adapter to Breathing Circuit Wye, page 1-11.
Operator’s Manual Addendum: Capnography
Using the ETCO2 Monitoring function
1.11.2 Disabling/enabling the Capnography Option
The Capnography option has two states: Enabled and Disabled.
Note: If the Capnography option has been disabled or enabled, SST does not have to be re-run unless the breathing circuit or other breathing system accessories have been changed (including the flow and CO2 combination sensor), removed, or added. To disable or enable the capnography monitoring function 1. At the ventilator setup screen, touch the configure icon. A menu containing tabs appears. 2.
Touch the Options tab. A screen appears containing Installed Options and CO2 tabs.
3.
Touch the CO2 tab.
4.
Touch Enabled or Disabled to enable or disable the Capnography option.
CO2 Waveform The CO2 waveform appears when the Capnography option is enabled and the waveform’s y-axis is configured to show CO2. The CO2 waveform displays the expired CO2 value as measured and reported by the capnography sensor at the circuit wye. Figure 1-9. CO2 Waveform
Operator’s Manual Addendum: Capnography
1-17
Capnography (ETCO2)
1.12
Accuracy Check No user-performed calibration is necessary or possible, except for zeroing the sensor. An accuracy check of the capnography sensor should be performed once per year.
WARNING: Before performing an accuracy check, ensure no patient is connected to the ventilator.
Before performing the accuracy check, ensure the Capnography option has been enabled. Reference Disabling/enabling the Capnography Option, page 1-17. Perform an accuracy check using the following items: Table 1-4. Parts Required for Accuracy Check Manufacturer
Description
Part number
Philips (formerly known as Respironics)
Gas regulator
6081-00
Air Liquide
Calibration gas [5% CO2 with the balance being Nitrogen] (carton of 4)
T4507NM-4PD (USA)
Air Liquide
Calibration gas [5% CO2 with the balance being Nitrogen] (sold by the can with a required minimum order of 6)
T4507SRI-PD (Other countries)
External barometer
For use in calculating the expected CO2 value obtained during the accuracy check.
Local supplier
To perform an accuracy check 1. Allow the calibration gas time to reach room temperature (approximately 30 minutes depending upon the ambient storage temperature of the calibration gas).
1-18
2.
Attach the capnography sensor to the ventilator at the connector port labeled CO2 on the ventilator’s front panel. Ensure the capnography sensor/adapters are not connected to the patient circuit.
3.
Connect three identical airway adapters end-to-end to the gas regulator. This configuration is called a stack.
Operator’s Manual Addendum: Capnography
Accuracy Check
Figure 1-10. Airway Adapter Configuration
1
Top of stack (smaller diameter)
2
Attach capnography sensor to middle airway adapter
3
Bottom of stack (larger diameter
4.
Turn on the ventilator and configure it for an Adult circuit type, if not already configured. To change the circuit type, SST must be performed.Reference To run SST in Chapter 3 of this manual.
5.
Set the ventilator up for a New Patient. The Quick Start settings may be used.
6.
Set the oxygen concentration to 21%.
7.
Connect a patient circuit to the ventilator and to a test lung. At the time the circuit and test lung are connected, the ventilator will sense a patient connection, and the waveforms display will appear on the GUI screen.
8.
Change the waveform display to show CO2 in mmHg, by double-tapping the y-axis parameter. A list of buttons appears with parameters.
Operator’s Manual Addendum: Capnography
1-19
Capnography (ETCO2)
9.
Touch the CO2 button. The waveform now shows CO2 in mmHg.
10.
Connect the capnography sensor to the middle airway adapter.
11.
Zero the sensor. Reference Zeroing the Sensor, page 1-15.
12.
Turn the gas regulator flow control valve OFF (turned fully clockwise).
13.
Attach the gas regulator and hose assembly to the calibration gas cylinder. Figure 1-11. Gas Regulator Attachment
1-20
1
Regulator output. Attach bottom of airway adapter stack (larger diameter) here
3
Flow control valve
2
Factory preset - do not adjust
4
Pressure gauge
14.
Connect the gas regulator output to the bottom of the airway adapter stack described in step 3.
15.
Provide a constant flow of the test gas (approximately 2 L/min) through the airway adapters by fully opening the valve, and allow the gas to flow for 30 s.
16.
Touch the pause icon for the waveform and use the knob to move the cursor along the waveform. Read the CO2 measurement appearing on the cursor.
17.
Turn the test gas off.
Operator’s Manual Addendum: Capnography