an aspirator in accordance with a preferred embodiment of the subject invention is identified generally by the numeral 10 in fig1 . the aspirator 10 includes a suction apparatus 12 , a processor 14 , a power supply 16 and a display 18 . the apparatus 10 further include additional inputs and outputs as explained further below . the suction apparatus 12 includes a manifold 20 with a fluid inlet 22 and a fluid outlet 24 . a tube 26 is mounted to the fluid inlet 22 of the manifold 20 and communicates with a collection canister 27 disposed externally on the aspirator 10 and connected to the suction apparatus 12 . the collection canister 27 in turn communicates with a hose and an appropriate suction catheter ( not shown ) that can be placed in communication with the patient . the exact configuration of the collection canister 27 and the suction catheter will vary in accordance with the specific medical use for the apparatus 10 and may be of prior art design . in this regard , a known collection canister is shown in the above - referenced u . s . pat . no . 5 , 954 , 704 . the manifold 20 further includes a variable orifice electronic valve 30 , such as a solenoid valve , that controls an air bleed between the fluid inlet 22 and the fluid outlet 24 . the electronic valve 30 can adjust the amount of the air bleed over the range between a fully opened condition and a fully closed condition . additionally , the variable orifice electronic valve 30 can be operative to open and close at a selected frequency or duty rate . operation of the electronic valve 30 is controlled by the processor 14 as explained further herein . the manifold 20 further includes a transducer 31 for sensing the negative pressure level at the manifold 20 and for generating a signal indicative of the value of the sensed negative pressure . the transducer 31 communicates with the processor 14 as explained herein . the suction apparatus 12 further includes a vacuum pump motor 32 that communicates with a pump head 34 . the pump head 34 in turn communicates with the fluid outlet 24 of the manifold 20 . the vacuum pump motor 32 and the pump head 34 cooperate to generate a negative pressure when the suction catheter becomes fully or partially occluded . the suction apparatus 12 further includes a motor speed control and tachometer 36 for controlling the operating speed of the vacuum pump motor 32 and for producing an output signal to indicate the actual speed of the vacuum pump motor 32 . the motor speed control and tachometer 36 communicates with the processor 14 . the motor speed control component receives information from the processor 14 that tells it to generate an airflow based on the current control setting for the set operating mode . the tachometer component communicated information back to the processor 14 and compares the information to see whether the flow set equals the flow measured . if the flow set does not equal the flow measured , the processor will adjust the signal to the motor speed control component causing the motor to speed up or slow down accordingly . as illustrated herein , the vacuum pump motor 32 , the pump head 34 and the motor speed control and tachometer 36 are included in the housing 19 of the suction apparatus 12 . however , one or all of these components can be disposed externally of the housing 19 . for example , the vacuum pump motor 32 and the pump head 34 can be in the housing 19 , while the motor speed control and tachometer 36 can be in a separate external module that may include the processor 14 . alternatively , the vacuum pump motor 32 and pump head 34 can be disposed externally of the housing 19 in a separate motor housing . the motor speed control and tachometer 36 can be in the same motor housing , in the suction apparatus 12 or in the processor 14 . the processor ( cpu ) 14 of the aspirator 10 is in two - way communication with the suction apparatus 12 to provide a closed - loop feedback between the suction apparatus 12 and the processor 14 . in particular , processor 14 has connections 38 to and from the variable orifice valve 30 and connections 40 to and from the negative pressure transducer 28 in the manifold 20 . the functional implications of the connections 38 and 40 as part of the closed - loop control feedback is described further below . the power supply 16 includes a connection 42 to a power input port 44 of the processor 14 so that the power supply 16 provides sufficient power for operating the suction apparatus 12 , the processor 14 , the display 18 , the motor speed control and tachometer 36 , the vacuum pump motor 32 and the variable orifice electronic valve 30 . the power supply 16 includes an internal power supply and power conditioning circuit 46 connected to the power input port 44 via the connection 42 . the power supply 16 further includes a battery pack 48 connected to the internal power supply and power conditioning circuit 46 for providing one optional power source . the power supply further includes an ac power supply and battery charger unit 50 connected to an external power supply and further connected to both the internal power supply and power conditioning circuit 46 and the battery pack 48 . a switch 52 is mounted to the power supply 16 and is operative for selectively switching between an off mode , a battery power mode and an ac power mode . when the switch is turned to the ac power mode , the ac power supply and battery charger 50 supplies power to the battery pack 48 for recharging the battery pack and further supplies power to the internal power supply and power conditioning circuit 46 for powering the aspirator 10 . the display 18 preferably is an lcd display that is connected directly to the processor 14 . the display 18 is operative for displaying a broad range of operating conditions as shown in fig1 and as described further herein . additionally , the lcd display may be a touch sensitive display that permits the operator to select sequential arrays of menu options as described below . the processor 14 includes other inputs and outputs independent of the suction apparatus 12 , the power supply 16 and the display 18 . significantly , the processor 14 is connected to a barometric sensor 54 that senses ambient barometric pressure conditions and provides barometric pressure data to the processor 14 on a real time basis . the processor 14 uses data from the barometric sensor 54 with data sensed by the pressure transducer 31 to vary the operation of the variable orifice valve 30 and the motor speed controller 36 . the aspirator 10 further includes an alarm 56 connected to the processor 14 and operative to produce an audible and / or visible alarm in response to certain conditions input to the processor 14 . for example , the processor 14 will trigger the alarm 56 in response to extreme ranges of vacuum , a pump failure , a power failure or the like as illustrated in fig1 . the processor 14 further includes a communication port 58 , such as a usb or rs - 232 . the communication port 58 enables connection to a remote controller which can monitor and control the aspirator 10 from a remote location . hence , a plurality of aspirators 10 can be controlled from a single remote location , while each aspirator 10 provides real time data at the communication port 58 . fig2 - 11 show one optional operating procedure for the aspirator 10 . with reference to fig2 , a first step s 1 of the procedure requires the operator to actuate the switch 52 of the power supply 16 in fig1 for supplying power either from the battery pack 48 or the ac power supply 50 . the processor 14 then will perform a self check for the various components of the aspirator 10 as indicated schematically by step s 2 in fig2 . as part of this step , the processor 14 will cause the display 18 to display a screen image , such as the preferred image shown in fig3 . upon completion of the self check in step s 2 , the processor 14 will allow the operator to choose between operations with the previous settings or with new settings as indicated at step s 3 . as part of this step , the processor 14 will cause the display 18 to display a screen image , such as the preferred image illustrated schematically in fig4 . more particularly , the screen image will display the previous operational mode ( e . g ., pharyngeal ) and operational limits ( e . g ., pressure level in mm of mercury and flow rate in liters per minute lpm ). in many instances , the operator will choose to begin operations with the previous setting , and the screen of fig4 will be programmed to indicate acceptance of the previous settings . as a result , the user need merely press the rotary encoder push button switch 60 shown in fig1 to enter the “ yes ” selection . the process then will proceed to step s 4 and to the operational start phase at input location j shown in fig2 . in other instances , the operator will want to select a new operating mode or program . as noted above , the processor 14 initially will cause the display 18 to display the acceptance of the previous settings . thus , to change the setting , the operator will turn the rotary encoder push button switch 60 of fig1 . this will cause the “ no ” image on the preferred display of fig4 to be illuminated . the operator then will press the rotary encoder push button switch 60 so that the processor 14 will direct the operator through the steps of selecting a new mode and / or program . the processor 14 will lead the operator through a series of menu options for selecting the appropriate mode and / or user program as indicated at step s 4 . at this step , the processor 14 will cause the display 18 to display an image , such as the preferred image shown in fig5 . the operator then will turn the rotary encoder push button switch 60 until the appropriate operational mode is illuminated . the operator then will push to rotary encoder push button switch 60 when the preferred operational mode has been illuminated . one option provided by the screen of fig5 is to select user programs distinct from the five optional operating modes of fig5 . step s 5 indicates the process step where the processor 14 determines whether the user programs option has been selected . in those instances where the user programs are selected , the processor will proceed to step s 6 as illustrated in fig6 . in this step , the processor 14 will cause the display 18 to identify the optional user programs that can be changed or restored . a typical screen image is illustrated in fig7 and displays to the user the option of changing default mode , changing default settings , restoring factory settings or exiting from the user programs option . the user will employ the rotary encoder switch 60 until the processor 14 causes the display 18 to illuminate the selected program option . step s 7 identifies a step where the processor 14 determines whether the operator has selected a change in the default mode . if this change has been selected , the processor 14 will proceed to step s 8 to permit the operator to select the new default mode or to “ exit ” if the operator determines that the existing default mode is acceptable . fig8 shows an optional preferred screen display that will permit the operator to select a new default mode or to exit from this user program option . once again , the operator will use the rotary encoder push button switch 60 to choose the appropriate option in fig8 and then to confirm that selection . the processor 14 will require the operator to confirm the selection made in step s 8 . this confirmation step is a fail safe procedure and is illustrated by step s 9 in fig6 . if the user chooses in step s 9 not to accept the new default mode , the processor 14 will return the operator to step s 8 for selecting a new default mode or for exiting from this option . if the user chooses in step s 9 to exit from this changing default mode option , the processor 14 will return the operator to step s 6 . if the user chooses in step s 9 to accept the new default mode then the processor 14 will direct the user to steps for selecting default settings for the selected default mode as explained below . the operator , in step s 7 , may choose not to change the default mode . under these conditions , the processor will determine in step 10 whether the operator wants to change the default settings . the operator will indicate a desire to change the default setting by rotating the rotary encoder push button switch 60 until the change default setting has been identified , such as in the preferred screen image shown in fig7 . the operator then will press the rotary encoder push button switch 60 . under these conditions , the processor will proceed to step s 11 . fig6 also shows that step s 11 will be reached under those conditions where the operator has chosen to accept the new default mode in step s 9 . the processor 14 will cause the display 18 to display the optional default settings as illustrated in the preferred screen image of fig9 . the operator then will use the rotary encoder push button switch 60 for choosing each of the optional settings . one of the optional settings shown in fig9 is “ exit ” which will be selected if the operator has determined that a different user program option should have been selected . after making the selections offered by fig9 and as part of step s 11 , the processor will require the operator to confirm the new default settings , as illustrated in step s 12 . one option is for the operator to exit this decision making step . in response to a selection of the exit option , the processor 14 will direct the user back to step s 6 for selecting one of the optional programs . alternatively , the operator could choose not to accept the default settings in step s 12 . under this selection , the processor 14 will return the operator to step s 11 and fig9 so that the operator can choose new default settings or exits from this decision process . of course , step s 12 permits the operator to accept the new default settings . under these circumstances , the processor 14 will proceed to a step for restoring factory defaults . the processor 14 will proceed to determine whether the operator has chosen to restore the factory defaults . the operator may choose in step s 10 not to change the default settings . as a result , the processor then will determine in step s 13 whether the operator chooses to restore the factory default settings . this preferred decision making screen is illustrated in fig1 , and the operator is given the option of either exiting or restoring the factory default settings . an operator who chooses to restore factory defaults will be directed by the processor to step s 14 and to the preferred screen image shown in fig1 . the processor then will direct the operator in step s 15 to either accept the factory default setting or to exit from this decision making process . an operator who chooses to exit from step s 15 will be directed back to step s 6 and to the preferred screen of fig7 . a user who chooses to accept the factory default settings in step s 15 will be given an option in step s 16 to either exit from this decision making process or to return to the selection of user programs described above with respect to step s 6 - s 15 . a user who chooses not to exit this decision making process will be returned to step s 6 . an operator who chooses to exit will be returned to the primary process of fig2 at input location h . an operator who has chosen not to select user programs or who has completed the selection of user programs , as outlined above and shown in the preferred screen images of fig6 - 11 , will be directed by the processor 14 to step s 17 in fig2 . in step s 17 , the processor 14 will display the current setting with a screen display similar to the preferred screen display of fig1 . the processor 14 then will give the operator the option in step s 18 of choosing whether to accept the current settings . an operator who chooses to accept the current settings ( step s 19 ) will be directed to input j for commencing the operation of the aspirator 10 . an operator who chooses in step s 18 and in fig1 not to accept the current settings will be directed to step s 20 by the processor 14 . the processor 14 also will cause the display 18 to display an image such as the preferred image of fig1 as part of step s 20 . the operator then will use the rotary encoder push button switch 60 with the fig1 display to make changes to the current settings . the processor 14 then will require the operator in step s 21 to affirm the acceptance of the changed current settings . an operator could choose to exit ( fig1 ) this part of the decision making and will be returned to step s 19 and then to input location j for starting the operation of the aspirator 10 . an operator could choose in step s 19 not to accept the changes ( fig1 ). under these conditions , the processor 14 will direct the operator back to step s 20 for further changing the current settings . however , the processor 14 further will give the operator the option in step s 21 and fig1 to accept the changes . the processor 14 then will direct the operator to step s 22 and onto the start of operations as indicated at step s 23 . the operator also will be directed to step s 23 ( via input j ) if the operator had chosen in step s 4 to begin operations with the previous setting or if the operator had chosen in step s 19 to begin or continue operations with the current settings . the processor 14 will cause the display 18 to display operating screens as shown , for example , in fig1 a and 168 . the version of the operating screens shown in fig1 a and 16b will be displayed and will vary in accordance with sensed operating conditions throughout the entire operation of the aspirator 10 . the operation indicated generally by step s 23 normally will continue for a considerable time and can be monitored on the display , as shown in fig1 a and 16b . however , the operation may be interrupted intentionally by the operator or due to unintended operating conditions . this interruption of the operation at step s 23 is assessed by the processor 14 at step s 24 . more particularly , an operator may determine that operational settings need to be changed . under these conditions , the operator will press the rotary encoder push button switch 60 twice in succession . this double pressing of the switch 60 identified in step s 24 will cause the processor to proceed to step s 25 and to the preferred screen image shown in fig1 . the operator then uses the rotary encoder push button switch 60 of fig1 b to choose a new mode ( step s 26 ) vacuum , airflow , on / off time parameter ( step s 27 ) or exit ( step s 28 ). an operator who chooses in step s 26 to select a new mode will be directed by the processor 14 to input location b and step s 4 . an operator who chooses to select a new setting of vacuum , airflow , on / off time in step s 27 will be directed by the processor 14 to input location c and step s 20 as described above . an operator who chooses in step s 28 to exit will be directed by the processor to input location d and step s 19 and further to input location j as described above for beginning the operation . if the operation of step s 23 is interrupted and if step s 24 determines that the encoder 60 was not pressed twice , the processor 14 will determine whether the alarm 56 has been actuated . if the alarm 56 has not been actuated , the processor will return to step s 23 to continue operation . if the processor 14 determines in step s 29 that the alarm has been actuated , the processor 14 will proceed to input location k shown in fig1 . fig1 shows the preferred logic employed by the processor 14 to determine the reason for the alarm . in step s 30 , the processor 14 will determine whether the battery is low or has failed . if the battery is low , the processor in step s 31 will cause the display 18 to advise the operator that the alarm can be muted and to advise the operator as to conditions that should be undertaken to address the low battery condition . the processor 14 determines in step s 32 whether the alarm 56 has been muted . if the alarm 56 has not been muted , the audible and visual alarm signals will remain active as indicated by step s 33 . if the alarm 56 has been muted as determined in step s 32 , then the display will include an icon in step s 34 confirming that the alarm has been muted . a predetermined mute period is programmed in the processor 14 . in step s 35 , the processor 14 will determine whether the mute period has ended . if the mute period is continuing , as determined in step s 35 , the processor 14 will ensure that the message of step s 34 continues to be displayed . if the mute interval has elapsed , as determined in step s 35 , the processor 14 will return to step s 30 . the processor 14 may determine in step s 30 that the battery is not low . under this condition , the processor will continue to step s 36 for determining whether external power is low . if the processor 14 determines in step s 36 that the external power is low , then the processor will proceed to steps s 37 - s 41 which substantially parallel the steps s 31 - s 35 as described above . if the processor 14 determines in step s 36 that the external power is not low , then the processor will proceed to step s 42 for determining whether the external power has failed or become disconnected . the processor 14 will proceed to step s 43 if a determination has been made that the external power has failed or has become disconnected . more particularly , step s 43 will give the operator the option of canceling the alarm message . the status of the alarm 56 is assessed in step s 44 . here the processor will return to step d of fig2 if the alarm has been canceled . thus , the processor 14 will continue through the operation , as indicated at input location j and step s 23 . on the other hand , the external power fail / disconnect alarm message will continue at step s 45 if the operator has not canceled the alarm 56 in step s 44 . the portion of fig1 from steps s 30 through steps s 45 assume that external power can be supplied or restored or a new battery can be activated so that the operation of step s 23 can proceed . however , the alarm sensed in step s 29 may be attributable to other causes . hence , if the alarm 56 is sensed in step s 29 and is not attributable to power related issues of steps s 30 , s 36 and s 42 , the processor 14 will proceed to steps s 46 - s 49 sequentially . in particular , step s 46 determines whether a high vacuum condition exists . this may be determined by input received by the processor 14 from the closed loop control feedback signal and control lines 38 and 40 that connect the processor 14 to the valve 30 and the transducer 31 . the determination in step s 46 that a high vacuum exists will cause the processor 14 to transmit a signal to display 18 for displaying a high vacuum message . additionally , audible and visual alarm signals remain active and cannot be muted . furthermore , the processor 14 will cease operation of the aspirator 10 . this problem can be cleared by recycling the on / off switch 52 . however , further service may be required if the condition persists . step s 47 determines whether the pump motor 32 has failed . this determination may be made by the connection 37 of the closed loop control signals in the control lines to and from the processor 14 and the motor speed control and tachometer 36 . once again , a sensed pump failure in step s 47 will cause the operation to cease . power can be recycled by operating the switch 52 . however , service may be required if the pump failure persists , and in this circumstance , the display 18 will indicate the need for such service . as with the high vacuum condition sensed in step s 46 , the pump failure sensed by step s 47 does not permit a muting of the alarm . step s 48 determines whether the self check of step s 2 in fig2 has occurred . the determination in step s 48 that the start - up self check has failed will cause operation to cease . the alarm 56 cannot be muted and the operation is not allowed . display 18 will display an appropriate service message . step s 49 determines whether there is a system failure that is not addressed by any of steps s 30 , s 36 , s 42 , s 46 , s 47 or s 48 . operation will cease if a system failure is sensed . however , a determination in step s 49 that there is no system failure will cause the processor to commence operation again at input location j and step s 23 . the preceding paragraphs describe optional ways for changing settings using the processor 14 . it should be understood , however , that the aspirator 10 continues to operate at its current setting until a change has been accepted . furthermore , a change in a setting may be initiated but not completed for any number of reasons . accordingly , the processor is programmed to return the screen to its previous setting image ( e . g ., fig1 a , 168 ) if there is a pause in the setting change greater than the pre - programmed amount of time . while the invention has been described with respect to a preferred embodiment , it is apparent that various changes can be made without departing from the scope of the invention as defined by the appended claims . for example , the apparatus and process has been described with respect to user input from a rotary encoder push button switch 60 . however , a touch screen input can be provided as well . of course , the screen images illustrated herein are only preferred examples , and many other screen images can be developed to convey similar information and to trigger similar decision making processes . additionally , the user input can be provided from a remote location and may include input provided from the keyboard of a computing device .
a digitally controlled aspirator is provided with a processor that allows the user to select operating conditions including one or more default settings . the processor further includes sensors for sensing operational and environmental conditions and adjusts the operation of the aspirator to reflect the sensed conditions .