Body Simulation
Body Simulation is built around the excellent physiologic and pharmacologic models of N. Ty Smith, M.D. The software is integrated with many aspects of relevant physiology to present users with the most life-like PC based flat screen anesthesia simulation available.
About the Body Simulation System
VIII. BODY SIMULATION WINDOWS - THE DETAILS
Clinical Windows:
Body Simulation for Anesthesia - Startup : The Opening Screen
The first screen you will see is the startup screen. It contains licensing information, and offers choices for starting your case. The choices are "Select Patient Now", "Quick Setup Now", or "Close This Window".
- Select Patient Now
This is the best option if you have never used Body before.
Choosing the "Select Patient Now" option will open another window prompting the user to select a patient. There are 6 patient choices. Single click on a patient and a brief patient description will appear in the Description window. Brief descriptions of the patients are the following:
- Pat01 - 44 year old healthy male.
- Pat02 - y/o hypovolemic male with bleeding ulcer.
- Pat03 - 84 y/o frail female.
- Pat04 - 39 y/o male. Heavy smoker with liver disease.
- Pat05 - 51 y/o obese male with renal dysfunction.
- Pat06 - 37 y/o female with COPD.
To select a patient, double clicking on one of the patient filenames, or single click on a patient filename and then click the "Open" button.
FYI: You can build your own patients if you like.
The option to "Use drugs from previous case" will allow a user to use the drug setup from the previous case. It saves the user from having to set up a new set of drugs. As of this printing this feature has not been implemented.
- Quick Setup Now
This option allows for using preset selection of the following:
- Selected patient
- Intravenous lines
- Fluids used for the case
- Monitors used for the case
- Drugs setup for the case
- critical incidents which will occur during a case
- Plot variables chosen for the case
- This option will save time for users whose goal is to get to parts of a case which do not involve setting up items from the above list. This will also assist situations where many individuals will run through the same case.
As of the printing of this manual, two Quick Setup files are provided with Body Simulation:
- BasicInductionHealthyPatient - for a basic induction scenario.
- HowLongDoIHave - for the "How Long Do I Have" scenario from this manual.
To select a quick setup, double clicking on one of the quick setup filenames, or single click on a quick setup filename and then click the "Open" button.
FYI: You can build your own quick setups if you like.
- Close This Window
This option closes the startup screen without selecting a patient or a Quick Setup.
This option may be used if you do not want to start a case immediately. For example if you would like to use Body to access the internet, or access the help system.
You may subsequently select a patient or a quick setup from the main menu.
Body Simulation for Anesthesia : The Main Window, and Main Menu
The main window of Body Simulation for Anesthesia is a parent window for other windows within Body. Practically, is simply a background for the other windows. It also provides access to the main menu.
- Main Menu
The main menu mostly allows users access to the different windows or views to the simulation. There are several setup items which are exceptions to this rule. Primary items in the main menu will be discussed one by one.
Case:
The case item controls a pull down menu which is broken into 4 sections. The sections are case control, the most recently used list (MRU), options, and quit.
Case control allows selection of patients, and opening or saving of Quick Setups. Fast forward mode may also be selected from this section. After a patient has been selected, the "Select Patient" item becomes "grayed out", meaning that it is unavailable for use. Body Simulation must be restarted if you want to select another patient.
The MRU list contains a list (5 items maximum) of the most recently used patients. Selection of one of these patients will cause that particular patient to be opened. The MRU list items are not available if a case is in progress. Body Simulation must be restarted if you want to select another patient.
The options section contains an Options item that clears all items from the MRU.
The quit section allows the user to quit Body Simulation. You will be prompted if you are sure you want to quit.
Setup:
This item allows access to the setup windows of Body. Those windows are IV Lines, Fluids, Drugs, and Monitors.
View:
This item allows access to other windows or views which the user may want to view on a regular basis. These items include patient info, the patient view, physiologic monitor, gases - or anesthesia machine, record - the automated anesthetic record, drugs, and case transcript.
Tools:
The Tools item contains an option to "Show rebreathing bag", or show the "Squeeze" window in the event you have closed it.
The tools item also allows the user the option to control the behavior of the "Pop-up dialog responses". Certain functions within Body will cause the O.R. personnel to respond or make comments. These comments show up in the patient view are of the "View Patient" window. This feature may be turned off from the tools item if the user does not want to be bothered by these responses.
Inspect:
As of this printing the Inspect item has no function.
Problems:
The Problems item allows access to the "Critical Incidents" window and the "Patient Condition" window.
Scientific:
This item allows access to all the scientific windows.
Help:
The Help item allows access to the help system. It also allows the user to find out information about the Body Simulation version, and the users' computer system parameters.
The Patient and Interaction Window : View Patient
The View Patient window will likely be the most heavily used window in all cases. This is where most of the interaction with the patient occurs. Starting in the upper left hand part of the window, and moving clockwise, descriptions of the various parts of this window are given.
The Main Viewport:
This is the picture in the upper left hand ¼ of the View Patient window. It takes up almost ¼ of the window, and presents the user with important information and views.
The patient summary is the first item seen in this window. To view the patient's face, click the "View Patient" button on the bottom of the "View Patient" window. To return to the patient summary, click the "Info" button on the bottom of the "View Patient" window.
Other views that may be seen in the main viewport are the thumb twitch for evaluation of neuromuscular block, the intubation sequence and intubation video, and text transcripts of O.R. personnel audio responses. This section contains information about how to initiate these 3 views.
IV Fluids Controller:
In the upper and lower center of the View Patient window is the IV fluids controller. This interface allows control of IV drip rate and control of pressure infusion for each infusion bag. Bag size, remaining volume, and bag contents are displayed.
To gain control of an infusion bag, click on it's label below the controller. The label just clicked will be indicated in the controllers label section. The selected infusion will now respond to drip rate changes (unless the bag is empty). When the bag is empty, you may replace or change it by accessing the "Setup" item of the main menu.
Fluids must be setup from the "Setup" item of the main menu before they can be used.
Drug Injection Area:
Drugs may be injected from this area only after they are setup. For drug setup access the "Setup" item of the main menu.
Once drugs are setup there are 3 ways to administer them from this area: 1). Click the "Inject" button. The syringe will start injecting in real time. The "Inject" button changes into the "STOP" button. The "STOP" button must be clicked to stop injection of the syringe. 2). The "Dose" button pops up a modal window that allows the user to select a precise dose of agent to be injected. When the "Inject" button (on this modal window) is selected, the window will close and the syringe will inject until the selected amount has been delivered. The "CMPT" pull down selector allows the user to select a compartment other that the normal venous compartment to inject the drug into. 3). Select the "Pump" button to access a syringe pump. Again a modal window will appear allowing entry of a drug rate in (mcg/kg/min). The patient's weight has been entered for the user, as a time saving aid, but may be overwritten. Other controls on the pump are self-explanatory.
Transcript button:
The Transcript button brings the case transcript into view. The case transcript shows text documentation of phrases spoken by participants in the O.R., and a few other noteworthy pieces of information.
Dialog button:
The Dialog button allows the user to communicate with O.R. participants including the patient, the surgeon, the nurse, and the assistant. Purposes of this communication are to assess patient status, to communicate with the surgeon, and to help troubleshoot critical incidents and other problems that may arise. The O.R. personnel act as your hands and eyes when it comes to troubleshooting problems.
The individual communications are fairly straightforward, but there are a few subtleties that require explanation. The patient will not respond if he/she is anesthetized or paralyzed, and will answer incoherently if there are appropriate levels of agent on board.
The surgeon will start surgery only when you allow him to do so. The surgery will suspend if the mean pressure is not low enough for the surgeon.
TO4 nerve stimulator:
Click on this icon to evaluate the level of neuromuscular block. The twitch of the thumb will appear in the main viewport.
Scan Room:
The scan room icons causes a sequence of images to rotate through its viewport. The images are representations of other significant items of interest in the O.R. These images may be used to help troubleshoot problems. Images that appear are:
- urine output
- blood loss
- surgery status (in progress, suspended, or complete)
- pressures of supplemental O2 and N2O tanks
- patient temperature:
Bellows icon:
This icon gives a representation of the volume of gas in the ventilator bellows and the pressure in the circuit. The pressure may be used to evaluate an airway or lung problem - such as a right mainstem bronchus intubation or a stuck valve in the ventilator circuit.
Clicking on this icon will cause mechanical ventilation to start or stop.
Mask icon:
Clicking on this icon will either place the mask on the patient or remove the mask.
When the patient is intubated, this icon becomes the "Extubate" icon. Click on this icon to extubate the patient.
Laryngoscope icon:
Click on this icon to initiate the endotracheal intubation procedure. When the intubation is complete, this icon will become the "Adjust Tube" icon. The adjust tube icon should be used to adjust the depth of the E.T. tube after the patient has been intubated.
And the end of the intubation procedure a window will appear allowing the user to adjust the depth of the tube. The window is the same that appears when the "adjust tube" icon is selected. The "Set" button on this window is the equivalent of securing the tube, and inflating the cuff.
Rebreathing bag icon:
This icon reflects the gas quantity in the rebreathing bag. Click on this icon to simulate squeezing the bag. Clicking lower on the image will cause a harder squeeze, clicking higher on the image will cause a weaker squeeze.
Physiologic Monitor : Patient Monitoring
This window is primarily non-interactive. Data on this window may be viewed only, not manipulated or adjusted. There are no alarms implemented.
Items to be monitored may be selected from the "Monitor" section of the main menu item "Setup".
The exception to the above is cardiac output. Click on the white cardiac output area of the monitor, and a thermodilution curve will appear on the monitor. The cardiac output with a timestamp of when the reading was taken will also appear in the parameter block.
Case Transcript : A transcript of audio interaction
This window contains the text phrases of what the individuals in the O.R. are saying, including the questions you have asked them. If you select the "Close" button, the window will be minimized within the Body parent window.
Anesthesia Machine : Control of Inhaled Anesthetic Agents and Ventilator
Select Drugs : Setup Drugs from the Drug Cart
Once an IV line has been inserted drugs may be setup by selecting the "Drugs" button from the bottom of the "View Patient" window, or by accessing the "Drugs" item of the "Setup" item of the main menu. This part of the setup is intended to be analogous to mixing drugs at the anesthetic workstation. The drug is mixed here, but not administered.
Drugs are grouped into categories of cardiovascular agents, induction agents, narcotics, neuromuscular blocking agents, miscellaneous agents, test drugs, and bronchodilation agents (the latter 2 categories are not used at this time).
Dosage information about a given drug may be obtained by clicking on the "Information" button at the bottom of the window, then clicking of the drug label of interest.
Clicking on a drug label selects that drug, then advances the screen to the next phase of drug selection. At this point the default option is to select from 1 of 6 syringe sizes. Click on the "Infusion" tab to mix the drug in a bag for administration via IV drip. In either case, click on the choice of bag or syringe. There is an option to choose which IV line this drug will be connected to, and what the concentration of the drug should be. Default drug concentrations are entered in the concentration box for convenience. Remember to select mg or mcg as required.
Click on "Accept" to complete the selection process for that drug. Up to 12 syringes and bags may be selected for a single case.
The "CLOSE" button closes the window brings the user back to the previous view.
Automated Anesthetic Record : Record of the Case
The automated anesthetic record may be accessed by the "Record" button on the bottom of the "View Patient" page, or from the "Record" item of the "View" item of the main menu. It appears as a modal window, and as such, it requires that the user close it before accessing other windows.
The automated record has some unique features that may require explanation.
The demographics section in the upper left hand corner is self-explanatory. The next section describes the phase of the case. Anesthesia Start time is the time that Body is launched. Anesthesia Ready is marked when the mask is placed on the patient, and Surgery Start in marked when the surgeon is allowed to commence the procedure (use the Dialog button). Surgery End is marked when the surgeon completes his procedure - the surgeon will inform you. The user should click the Anesthesia End button when the case is complete.
The Operations section indicates the nature of the surgical procedure, and any other special procedures.
The indications for which monitors are used during the case will be filled in automatically.
The Notes section should be filled in by the user.
The % Agent strip will indicate the percent of agent flow with color-coded bars. Similarly, the Flow section, just below the %Agent section, indicates the total gas flow with color coded bars. The bars may be divided into two colors representing gas mixtures. The possibilities are O2 & Air or O2 & N2O. The colors for each gas are specific to the country the software is localized to. Gray dots are plotted in this region to form a line to give a graphical indication of ET CO2. Data from this section is plotted is 30 second intervals.
The next section down gives text values for time in 15 minute intervals, and ET CO2, blood loss, and urine output in 5 minute intervals.
The bottom section gives graphical values for temperature, systolic and diastolic blood pressure, heart rate, SpO2, and respiration rate. These data are plotted in 2 ½ minute intervals.
Setup Intravenous Lines : Setup the IV Lines for the Case
The large "Setup IV Lines" button in the upper center of the "View Patient" screen allows access to the intravenous line setup. Bring the cursor over the outline of the patient. The cursor changes to a pointing hand where an IV line may be inserted. A text description will appear briefly indicating the name of the insertion site.
When the site is selected a popup menu will appear prompting selection of a cannula size. Select the appropriate size, and a graphic of the insertion site will appear. The site name will also appear in the "Intravenous Lines" list on the right hand side of this window. The outline of the patient is intended to be transparent (i.e. not to give front or back specific details of the appearance of the arm).
The anatomy buttons showing vascular structure are for educational purposes only, and do not have a specific function in the software.
Once the IV lines are selected, the user has the option to proceed directly to the fluid setup (click "Setup Fluids") or to close the window and return to the previous one (click "Done"). The user may select "Cancel" to return to the previous window without having made any changes.
Once the IV lines have been setup initially, the "Setup IV Lines" button vanishes and the only way to get back to the IV lines setup window is via the "IV Lines" item of the "Setup" item of the main menu.
It is necessary to setup IV lines in order to administer injected agents.
Setup Fluids : Select Fluids and Connect to IV Lines
Access to the fluids setup window is gained from the "Setup Intravenous Lines" window, from the "Fluids" item of the "Setup" item of the main menu, or through the "Setup Fluids" button that may appear in the upper center section of the "View Patient" screen (under certain circumstances only).
To setup fluids:
- Select an intravenous line (from the Intravenous Lines box)
- Click the "Add a New Fluid to this IV Line" button
- Select the fluid of choice under the "Select a Fluid" section
- Select the appropriate bag
- Select the "ACCEPT" button
There is no limit to the number of fluids that may be connected to a given IV line. Setup fluids on all the lines required for the case, then click "Done" to close the window.
Setup Monitors : Select Monitors to be Used During the Case
The "Setup Monitors" button a the bottom of the "View Patient" window allows access to the monitor setup. Click on the items that are to be monitored. Consequences of, and comments pertaining to monitoring techniques are presented to the user as a reminder.
After the monitors are setup the first time, the "Setup Monitors" button changes its function to a button which brings up the monitor window. To access the monitor setup page subsequently, use the "Setup Monitors" button from the bottom of the monitor window, or from the "Monitors" item of the "Setup" main menu item.
Click on the new "Monitor" Button at the bottom of the "View Patient" window to view the monitor.
Critical Incidents : Setup Critical Incidents to Occur During the Case
To set up a critical incident, access "Critical Incidents" from the "Problems" item of the main menu. A window will appear with a tab-box of possible incidents. Look through the list to acquaint yourself with the critical incidents that are simulated.
Under "Select Trigger Events" there are times and triggering events for initiation of incidents.
Different incidents require different interventions. Usually it is the assistant or the nurse whom you will ask to assist with diagnosis or intervention. Explore the "Dialog" feature to find the options available.
The incidents are listed with their mechanisms for control, evaluation, and action for correction:
Bleeding
Control
The user can control the rate of bleeding and its duration, and thereby its total quantity. Since ECF fluid will replace some of the lost blood, the change in blood volume will not be the same as the amount of blood lost.
Evaluation
Any number of cardiovascular measurements. Stroke volume shows the greatest change. "Blood volume," under Dynamic Plots, General, gives the diagnosis.
Action
Administer electrolyte, sugar solution, or packed cells.
Leaking Mask
Control
Select the desired degree of mask leak.
Evaluation
It will be difficult to generate the required tidal volume, hence your patient will begin to show signs of underventilation.
Action
You will have to squeeze the bag harder (lower down on the bag image), or set the ventilator tidal volume higher. Replacing the mask may improve the situation. Deselect the incident to completely remove its effect.
Leaking Cuff
Control
Select the desired degree of the endotracheal tube cuff leak.
Evaluation
It will be difficult to generate the required tidal volume, hence your patient will begin to show signs of underventilation.
Action
Reseting the tube will solve the problem.
Laryngospasm
Control
The user can control the degree respiratory obstruction. 100% obstruction is, of course, total airway obstruction. This event will be triggered only by the administration of thiopental to the patient. Remember that the event must be activated before the thiopental is administered.
Evaluation
CO2 and airway pressure wave forms; X-Y Plots. The latter show airway obstruction very dramatically.
Action
Administer 100% O2 to attempt to break the spasm. Give succinylcholine after thiopental for mask ventilation; or administer a neuromuscular blocking agent after intubation.
Difficult intubation
Control
Select the degree of difficulty, or how long the intubation will take. In the severe case, intubation will be impossible.
Evaluation
The intubation time will be extended. The patient is not receiving O2 at this time, and the SpO2 may begin to drop.
Action
Abort the intubation. You must clear the incident to remove the problem. (Future versions of BODY will include alternate methods of intubation).
Esophageal intubation
Control
The user can control the number of attempts before tracheal intubation is achieved.
Evaluation
CO2 is absent and airway pressure is increased. SpO2 will, of course, eventually decrease, but we hope that the incident is detected before that. If you don't believe that was an esophageal intubation, run the video again and watch closely as the tube is approaching the glottis. At the last instant you will see the tube slide off the glottis and into the esophagus.
Action
The following is just a suggestion and is mainly intended to remind you what to click. If this incident is combined with airway obstruction, the resulting "can't ventilate, can't intubate" scenario is scary.
Remove tube by clicking on extubate image.
Replace mask by clicking on mask image.
Ventilate patient with 100 % O2 as necessary.
Remove mask.
Try intubation again.
Repeat until intubation is successful, or you decide to do the case by mask - perhaps with spontaneous ventilation - or abort the anesthetic.
Right mainstem intubation
Control
Set the event. This event changes the effective distance of the patient's teeth to carina. If the user does not ask the assistant to check HMD (hyoidmental distance), and the user sets the tube at 22 cm, the mainstem intubation will occur. The problem will also occur if the user sets the tube at a depth of more than 22 cm for a normal patient.
Evaluation
The airway pressure is increased. The assistant will have difficulty establishing that the breath sounds are clear and even. Eventually the SpO2 will drop.
Action
Attempt the intubation again. Set the tube at a better (lower) estimate of teeth to carina distance.
Expiratory valve jammed open
Control
Select the incident.
Evaluation
The expiratory valve will not prevent expiratory limb gas from entering the patient's airways during inspiration. ET and inspired CO2 concentration will increase depending on the fresh gas flow. Oxygen and agent concentrations delivered to the patient will be different than expected.
Action
You must ask the assistant to check the circuit. The assistant will resolve the problem for you once it is detected.
Expiratory valve jammed closed
Control
Select the incident.
Evaluation
The expiratory valve will impede expiratory gas flow. Ventilation will be difficult or impossible, and increased breathing circuit pressure will increase the intrapleural pressure and impede venous return. Cardiac output and mean arterial pressure will drop to potentially dangerous levels.
Action
You must ask the assistant to check the circuit. The assistant will resolve the problem for you once it is detected.
Inspiratory valve jammed open
Control
Select the desired percentage of the inspiratory valve leak.
Evaluation
The inspiratory valve will not prevent inspiratory limb gas from returning to the bag or ventilator during expiration. ET and inspired CO2 concentration will increase depending on the fresh gas flow. Oxygen and agent concentrations delivered to the patient will be different than expected.
Action
You must ask the assistant to check the circuit. The assistant will resolve the problem for you once it is detected.
Inspiratory valve jammed closed
Control
Select the desired percentage of the inspiratory valve obstruction.
Evaluation
The inspiratory valve will impede inspiratory gas flow. Ventilation will be difficult or impossible, and signs of patient underventilation will be apparent. Gas will be vented from the pop off valve.
Action
You must ask the assistant to check the circuit. The assistant will resolve the problem for you once it is detected.
Ventilator failure
Control
The user can select the replacement time for the ventilator as 5 minutes or irreparable.
Evaluation
Observe airway pressure and CO2 wave forms. View the X-Y Plots on the Dynamic Gas Display window. Observe pressure, flow, and gas plots on Dynamic Time Plots.
Action
Change from ventilator to bag.
Squeeze bag by clicking on bag or icon.
The new ventilator will automatically be installed after you ask the assistant to "Check the circuit".
Soda lime exhausted or partially exhausted
Control
Select either complete or partial soda lime exhaustion.
Evaluation
The inspiratory CO2 increases, followed by the end-tidal CO2. CO2 is observed in the breathing circuit, particularly at lower fresh gas flow settings.
Action
Ask the assistant to replace the soda lime, or you may increase the fresh gas flow.
Y-piece disconnect
Control
Select the incident.
Evaluation
It will be difficult or impossible to generate the required tidal volume, hence your patient will begin to show signs of underventilation.
Action
You will have to squeeze the bag harder (lower down on the image), or set the ventilator tidal volume higher in attempt to increase the delivered tidal volume. You must ask the assistant to check the circuit. The assistant will resolve the problem for you once it is detected.
Wall O2 pressure loss
Control
Select the incident.
Evaluation
When wall O2 pressure is lost, supplemental O2 is not available until the assistant is asked to turn on the O2 tank. If the balance gas is N2O, the flow will be shut off. If the balance gas is air, the flow will continue with 21% O2. No alarms will be heard, so be alert!
Action
Ask the assistant to turn on the O2 tank.
You must use the O2 tank for the remainder of the case. Watch its level carefully.
O2 cylinder pressure loss
Control
Select the incident.
Evaluation
When wall O2pressure is lost, supplemental O2 is NOT available until the assistant is asked to turn on the O2 tank. If the anesthesia machine check hasn't been done, one could find the O2 tank empty. If the balance gas is N2O, the flow will be shut off. If the balance gas is air, the flow will continue with 21% O2. No alarms will be heard, so be alert!
Action
Ask the assistant to change to O2 tank. This could take a bit of time.
Vaporizer failure
Control
The vaporizer malfunctions. Select the overdose or underdose as desired.
Evaluation
The patient receives and unexpected concentration of agent.
Action
Discontinue use of the agent or deselect the incident.
IV line disconnect
Control
Select the which IV line is to disconnect.
Evaluation
Neither fluid, nor agents on the selected line are delivered to the patient.
Action
Ask the assistant to verify the IV lines or deselect the incident.
Drug syringe swap - ( NOT AVIALABLE this version)
Control
Select the incident. The intention is to simulate the effects of the wrong drug being administered.
Evaluation
If you have more than one injected agent selected, the effects of one of the agents will have that of one of the other selected agents. The agents swapped are agents which have very different cardiovascular effects.
Action
Good luck.
Inhaled agent swap - ( NOT AVIALABLE this version)
Control
Select the incident. The intention is to simulate the effects of the wrong drug being administered.
Evaluation
Unexpected results of blood pressure, ECG, etc. If inhaled agent monitoring is selected the real agent being administered will appear on the monitor.
Action
Good luck.
Monitor failures
Control
Various monitor failures are available. Select the desired failure.
Evaluation
Either loss of signal or erroneous signals will occur.
Action
Ask the assistant to replace the monitor.
Bi or Trigemini
Control
The user can select bi or trigemini simply by selecting the appropriate button. The presence of PVC's can also be induced by hypercapnia; the higher the PaCO2, the more frequent the PVC's. The PVC threshold is lowered by halothane.
Evaluation
Listen to the SpO2 sound, or look at the physiologic monitor.
Action
The event duration is determined by turning the event on or off. The event may be controlled by administration of an antidysrhythmic agent.
Myocardial depression
Control
Select the incident. This incident represents a spontaneous myocardial depression. Myocardial contractility is reduced.
Evaluation
View the physiologic monitor.
Action
Deselect the incident.
Future versions of BODY will expand this list. Your suggestions are welcome.
Patient Condition : Setup or Modify Patient Pathophysiology
This window is available by accessing "Patient Condition" from the "Problems" item of the main menu.
The user is given access to model components that make up the patient's physiology. These components may be changed, and the new patient may be saved for subsequent cases. The following aspects of the patient's physiology may be modified:
Renal failure
This setting determines the efficiency of the kidney with respect to eliminating drugs. Renal blood flow is not affected by this condition.
Hepatic failure
This setting determines the efficiency of the liver with respect to eliminating drugs. Hepatic blood flow is not affected by this condition.
Pulmonary Shunt
This setting determines the percentage of the pulmonary shunt. The parameter that is modified is the pulmonary shunt resistance. Notice that a percent value of the shunt is given. This percent value is calculated based on average blood flows through the pulmonary system. After modifying the shunt resistance the blood flows, and hence the calculated percentage value of shunt, will take a few seconds to reach steady state.
Squeeze : Squeeze the Re-breathing Bag
The squeeze window is an important window for using Body Simulation effectively. The squeeze window is a "stay-on-top" window that remains accessible from most of the other views and windows of Body Simulation.
Simulation control items present on this window are described starting on the top right hand side of the window:
Simulation time box: Gives the elapsed time since Body Simulation was launched. This time is mostly for your reference. The anesthetic record uses the real time system of your computer's internal calendar clock.
Freeze: The freeze control allows the user to pause or temporarily suspend the patient's state in time. It is a useful control to use while giving explanations, or if you have to leave the room, or take attention off of your simulated case for a while. Using this technique allows you to do all of the above without the fear that your patient might die in the absence of care.
Fast Fwd: This control is analogous to the fast forward on a VCR. It forces the simulation to execute as fast as the processor will allow. Simulations may execute up to 20 times faster than real time on Pentium II computers with the Windows NT operating system. This is extremely useful when plotting long term plots, or rapidly passing through mundane parts of your case. Note that Body Simulation executes much faster under Windows NT than under Windows 95 or Windows 98.
Mute All: Mutes all sounds that Body Simulation would normally produce.
Mute SpO2: Mutes the sound of the pulse oximeter beep.
Pop-off pressure: Allows the user to increase or decrease the pop-off valve pressure setting. It is necessary to increase this setting to manually ventilate the patient. If you do not decrease this setting when the patient begins to breath spontaneously the circuit will become pressurized to the selected value.
Bag icon: This icon is a replica of the rebreathing bag icon on the View Patient window. Click on this icon to simulate squeezing the rebreathing bag. The lower on the bag you click, the harder the squeeze will be. The image of the bag reflects the volume of gas in the bag. If the bag icon repeatedly show the words "bag empty", try increasing the pop-off pressure.
Scientific Windows:
All scientific windows may be accessed from the "Scientific" item of the main menu, and all require additional computer memory while they are open. It is good practice to close each scientific window when its use is complete.
Dynamic Time Plots : Real Time Data Plots vs. Time
The Dynamic Time Plots allow plotting of many physiologic variables within the simulation versus time.
To add variables to the plot list, click the button at the top of the window labeled "Add Variables". You will be presented with the "Select Plot Variables" window.
Select Plot Variables:
There are three tabs for selecting variables. The first is the "Plot General" tab that allows selection of variables in the "Select variables for plotting" box. Clicking on the variable description will cause the variable to appear in the "Selected Variables" box.
The "Plot Drugs" tab allows selection of concentration or mass of any of the mixed drugs or agents in any of the simulated compartments. Clicking on any combination will cause that combination to appear in the "Selected Variables" box.
Clicking on any of the items in the "Selected Variables" box will remove them from the box. Click on "Clear" at the bottom of this box to clear all the selected variables.
The "Plot Sets" tab allows saving or recalling of a set of plot variables know as a Plot Set. You may recall Plot Sets to quickly set up variables and their scaling required for certain cases, or you may save your Plot Set for future use. The next paragraphs describe the procedure for saving and recalling Plot Sets.
Once variables are entered in the "Selected Variables" box, turn to the "Plot Sets" tab and prepare to save a Plot Set. Enter a memo for your Plot Set in the memo box. To enhance usability of this feature, the memo should explain exactly what the intended use of the Plot Set is. Now, click the Save button. You will be prompted to provide a name for your Plot Set. Choose a name that is less than 32 characters, but is indicative of what the Plot Set is intended for.
To recall a Plot Set click the Open button. The Open file dialog appears, and you will be able to view the memo for each Plot Set by single - clicking on the Plot Set name. When you have found the desired Plot Set either double click on it, or click on the Open button.
If you accidentally select the wrong Plot Set click, "Clear" at the bottom of the "Selected Variables" box, or click on each selected variable individually.
Select "Cancel" to go back to the Dynamic Time Plots without having made any changes.
Select "Done" to accept your changes and continue with the Dynamic Time Plots.
Variables added to the Dynamic Time Plots they will appear in the plot list box on the left side. Click on a variable in the box to have the full variable name appear as the graph title, and the scales for that variable appear on the Y axis. Variables names are color coded to agree with the color of the plot line.
The Y axis scale may be modified by sliding the cursor over the Y axis label for the minimum value (at the bottom of the Y axis), or the Y axis label for the maximum value (at the top of the Y axis). When the cursor slides over these labels an edit box will appear allowing the user to enter a new scale value for maximum Y or minimum Y.
The time scale is controlled using the up-down buttons at the bottom of the window. Hours, minutes, and seconds may be controlled individually. The minimum time scale selectable is 3 seconds and the maximum is 60 hours.
Clear the plot screen by clicking on "Clear" at the bottom of the window.
The default setting of the "Wrap" feature is Wrap on. When the sweep bar gets to the end of the screen it will wrap around to the beginning wiping out all existing data on the screen as it sweeps. You may disable the wrap effect by clicking the "Wrap" button at the bottom of the window.
Plots may be recorded, and recorded plots may be played back.
Record, Playback:
Select "Record" at the top right of the window if you want to record data you are plotting. You must select record prior to having any data recorded (i.e. If you select "Record" after seeing something interesting, the past data will not be recorded).
When you are done recording you must manually deselect the "Record" button. The recording will continue until you do so. When you deselect "Record" you will be asked to provide a memo for the recording. Please provide an informative memo. You will then be asked to supply a name for your recording. Again, the name should be less than 32 characters, but as indicative of the nature of the data as possible.
To replay data click the "Replay" button. You will be presented with a dialog box that allows viewing of the informative memo you previously entered. Double click on the item name, or click the Open button to continue with the replay. Deselect replay to continue with regular real-time plotting.
Dynamic Gas Display : Graphical View of Gas Data in Airways
The Dynamic Gas Display shows the flow an concentration of gases in the anesthesia breathing circuit and patient airways. The gases are color coded according to standards for the country that the Body is localized for.
The different windows containing Dynamic Pie graphs represent concentrations at various places in the circuit. The first Dynamic Pie shows the gas concentrations at a selected point in the circuit. Use the pull down menu to select the area of the circuit you are interested in. Areas are indicated by the red letters on the circuit graphic. Note that the radius of the Dynamic Pie is constant and has no significant meaning.
The next Dynamic Pie is for fresh gas flow. In this Pie, concentrations are not only shown, but the area of the Pie is proportional to the fresh gas flow. In the next two Pies the area of the Pies are proportional the tidal volumes indicated. Also, the two pies inside the patient image have their areas proportional to each lung's volume.
Click the ventilator button in the lower left part of this window and an abbreviated version of the anesthesia machine control panel will appear. Ventilator control may be done from this panel. This feature is added for convenience - you will be able to see relevant changes on the Dynamic Gas Display without having to flip through different windows.
There is a data box on the right hand side of the screen that shows text data of respiration related data and X-Y plots of respiration data. These data are self-explanatory.
Drug Bars : Representation of Drug Concentration and Mass in the Compartments
The Drug Bars feature is one of the many outstanding features of Body; we predict that you will find many uses for it. It allows the user to follow the concentrations and masses of an inhaled or injected agent in the tissue and blood sub compartments of all the compartments currently in Body. The following describes how to use the features.
Select Drug.
Click on the arrow to obtain a pop down menu. Nitrous oxide, halothane, isoflurane and epinephrine are available by default, in addition to any drugs that you have chosen in Drug Setup. Single-click on a drug to view its concentrations and masses. Try dragging the window to the upper right-hand side of the screen, freezing the simulation while you inject an agent or start an inhaled agent, clicking on the Drug-Bars screen, and unfreezing the simulation. Watch the drug move through the circulation and into the tissues. If you are observing an inhaled agent, you may wish to use Fast Forward.
Drug Concentrations
The white bars give the concentrations in each compartment. Note that the concentrations are related to the IC50 and are relative, not absolute, concentrations. The red-green divide relates to the MAC, or IC50, for inhaled and injected agents, respectively.
Concentration-Effect Curve
This shows the concentration-effect for the drug in the appropriate compartment for the agent-brain gray, myocardium, or muscle.
Drug Mass in Compartments.
This has a tendency at the moment to overload, since the masses in muscle and, much more slowly, fat can reach enormous values.
Here is one way to use the Drug-Bars window, along with other windows. Use your imagination to come up with other ways. The following was done on a 14-inch laptop screen, but you might want a larger monitor screen, permitting less overlap among the screens. Open Drug Bars, the Monitor, Dynamic Plots, Insight into Model, and Patient View, the last so that you can see the patient's face. Give about 350-400 mg thiopental, as a bolus. Now you can watch the patient's eyes, the beat-to-beat cardiovascular effects on the monitor, the concentrations in the brain and the position on the concentration-effect curve in Drug Bars, and observe the physiologic and pharmacologic trends in the Dynamic Plots.
Once you feel comfortable doing this, try an infusion of propofol, for example. You will be surprised how you can learn to titrate an infusion with all this information. Next, try a bolus of propofol, followed by an infusion.
Inside Body
This feature shows four variables: Depth of Anesthesia, Neuromuscular Block Level, and brain and myocardial O2 deficit. Depth of Anesthesia is determined by the position on the brain-gray concentration-effect curve. If more than one drug is used, the concentration-additive calculation of Loewe is used. NMB Level is also determined by the position on the muscle CE curve, with the same interaction consideration for more than one drug.
Brain and Myocardial Oxygen Deficit relate to the oxygen supply-demand of these two organs. Body keeps track of the supply, including blood flow, PaO2, O2 concentration in the plasma, Hb concentration, SaO2, and release of oxygen by Hb. The demand relates to the O2 consumption, which is available in each compartment of Body. The consumption changes with depth of anesthesia.
