Surgery – Means for introducing or removing material from body for... – Gas application
Reexamination Certificate
1999-11-12
2002-06-11
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Gas application
C600S560000
Reexamination Certificate
active
06402714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an insufflation apparatus improving the accuracy, safety and speed of insufflation of fluid into a human or animal body. Particularly, the invention relates to an apparatus adapted to regulate the pressure inside a body cavity by controllably increasing an interruption phase of an insufflation pulse upon identifying obstructions encountered by a Veress needle during and after its penetration into the body cavity.
BACKGROUND OF THE INVENTION
Surgical procedures require the insufflation of fluid into a body cavity. Known insufflation apparatuses pass a fluid from the pressurized reservoir through the fluid line and an insufflation or Veress needle into the body cavity required to be maintained at a certain pressure.
The pressure to be regulated is the pressure of the patient, however, the pressure sensors are found inside the apparatus and measure the insufflation pressure upstream of an insufflation needle penetrating a patient's body. Both pressures are only equal if no gas is flowing through the needle. This is the reason that electronic insufflators do not fill the operation area continually, but only in phases. A combination of a filling phase and an interruption phase during which the gas flow is constantly brought back to zero in order to measure the pressure of the patient constitutes a pulse.
U.S. Pat. No. 4,048,992 to Lindemann et al., discloses a pressure gauge reading a back pressure of insufflated gas built up with the predetermined insufflated gas volume upstream of a Veress needle. As time passes, the pressure differential across the needle becomes equal to zero as indicated by a zero flow rate on a flow gauge, thus making a user assume that the pressure inside a cavity is equal to the back pressure.
U.S. Pat. No. 4,676,774 to Semm et al., discloses an apparatus for the insufflation of gas into a body cavity and including a pressure gauge, whose measured value is fed as a function of time into an electronic evaluation circuit and is converted into the intraabdominal pressure. Such measurement is based on the experience that shortly after the start of insufflation, steady-state conditions occur so that the measured value of the pressure gauge is approximately constant. Since the measured value of the pressure gauge is time differentiated, the first derivative is equal to zero and corresponds to the insignificant intraabdominal overpressure built up in the cavity. Thus, the pressure on the pressure gauge upstream of the insufflator indicates the insufflator's flow resistance and is constant. In order to calculate the static intraabdominal pressure the pressure at the start of insufflation has to be subtracted from the measured rising pressure.
U.S. Pat. No. 4,715,372 to Philippbar et al., discloses a gas insufflation apparatus for use in an arthroscopic attachment for a laser system in order to distend a joint during arthroscopic surgery. The apparatus includes a first regulator insufflating the gas directly into the knee joint at a minimal pressure and a second regulator applying the gas at a maximum pressure into an arthroscopic attachment.
U.S. Pat. No. 5,006,109 to Douglas et al., teaches a system for administering gas to a patient during an endoscopic procedure. The system includes a pressure regulator and a volumetric gas flow regulator continuously reflecting the pressure and flow rate of the gas which allow the user to modify these parameters during the procedure.
U.S. Pat. No. 5,360,396 to Chan discloses an apparatus for insufflation of a body cavity including a pressure reliever that allows the insufflating gas to escape if the pressure at the exit of a pressure reducer exceeds a predetermined pressure.
U.S. Pat. No. 5,439,441 discloses an insufflation device having a regulating device that is programmed to process and to store pressure reading values in the body cavity during each pause phase at which the introduction of gas into a body cavity to be inflated is discontinued. These readings are taken at plural, discrete intervals of time. The difference between a predetermined number of the most recent pressure reading values are compared to determined the pressure differential between highest and lowest pressure reading values. A series of results indicating that this pressure differential is less than a predetermined value determines that the pressure in the body has stabilized and equal to the pressure upstream of a needle inserted in the cavity.
U.S. Pat. No. 4,874,362 to Weist discloses a device and method for continuous insufflation wherein the intra-abdominal pressure is measured at an end of each cycle when a flow rate of gas is indicated to be zero. The rate is brought down to this value by controlling a pressure reducer that electrically connected with a CPU and whose working mode is a function of a clock generator and a nominal pressure generator. Particularly, the pressure reducer valve operates in two different modes. The first mode is characterized by maintaining a nominal pressure if a flow rate does not exceed a preset value. The pressure reducer is switched to the second mode, wherein an output pressure of the reducer is increased to a maximum insufflation value if the flow rate exceeds the preset value. The device disclosed in this reference operates without taking into consideration certain factors negatively affecting measurements of the intraabdominal pressure, for example, presence of gas flow through a Veress needle while a flow rate gage clearly indicates its absence.
All of the above disclosed devices are based on the premise that when an internal apparatus gas flow is brought back to zero at the end of a filling phase, no gas flows through a Veress needle into a body cavity thereby allowing correct determination of the intracavity pressure. During a surgical insufflation procedure of
FIG. 1
, an insufflation pressure P
ins
is shown to decay through a Veress needle in a relatively abrupt manner upon terminating a filling phase. Upon indicating a zero flow rate upstream of the Veress needle by a flow rate gauge, an equalization state between the insufflation pressure and an intracavity pressure P
abd
is presumed to be reached and the intracavity pressure is measured within the interruption phase T
i
=T
c
−T
p
of the pulse.
However, in many instances gas still flows through the Veress needle upon the presumed balance between the insufflation and intracavity pressures, thereby rendering the result of determination to be erroneous, as shown in dash lines in FIG.
1
. The rational behind this phenomenon is the accumulation of gas at the upstream end of the Veress needle during a filling phase.
Typically, this is a result of obstructions encountered by the Veress needle during a surgery. For instance, during the pneumo-peritoneum penetration the needle may encounter the skin, the intra-abdominal wall, muscles. Each of these parts of a body adds to the dead volume of fluid that may eventually render the measurement of intracavity pressure dangerously low compared to an actual value.
Further, a modern high flow insufflator is capable of producing a gas flow rate up to 30 l/min that might be necessary in some surgical procedures at a phase when the intracavity pressure has stabilized. Many practitioners, knowing a desirable rate of gas flow, set a high target value at the start of insufflation. However, since the opening of the Veress needle allows only a low gas flow, usually not exceeding 2-2.5 l/min, the dead volume in front of the Veress needle is “filled” with the maximum insufflation pressure. On completion of the filler phase, if the apparatus reduces the gas flow back to zero in order to measure the intracavity pressure, then there is still a pressure differential between the upstream and downstream ends of the needle. This dead volume decays through the needle into the cavity. Thus, although an internal apparatus gas flow is equal to zero, in fact gas flows from the dead volume in to the patient making measurements of the intracavity pressure errone
Casler Brian L.
Karl Storz GmbH & Co. KG
Sirmons Kevin C.
St. Onge Steward Johnston & Reens LLC
LandOfFree
Apparatus and method for controlling high flow insufflation does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus and method for controlling high flow insufflation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for controlling high flow insufflation will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2932879