Surgery – Respiratory method or device – Respiratory gas supply means enters nasal passage
Reexamination Certificate
2002-06-28
2003-10-28
Lo, Weilun (Department: 3761)
Surgery
Respiratory method or device
Respiratory gas supply means enters nasal passage
Reexamination Certificate
active
06637434
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gas delivery apparatus for administering a gas to a patient during surgery, and more particularly for delivering anesthetic to a patient during surgery
During surgical procedures, there is a need to anesthetize a patient in order to eliminate, or at least reduce: pain associated with the procedure; and movement of the patient during the procedure. Anesthesia is considered a drug-induced depression of at least a portion of nervous system, or portion thereof, of the patient.
In the sequence of events of drug-induced depression of the central nervous system, there occurs a level of depression that allows the muscles of the pharynx (e.g. the tongue) to relax causing soft-tissue structures to collapse into and obstruct the airway. This happens at an earlier stage than that at which the muscles of respiration (e g the diaphragm) cease to function. In other words, a condition known as “obstructive apnea,” where the diaphragm is struggling to pull air through an obstruction of the upper airway occurs before the diaphragm itself ceases to function (“central apnea”). In this sequential depression of the central nervous system, death occurs from Asphyxia before the drug itself can produce complete depression of the nervous system.
An upper airway obstruction occurs upon the induction of almost every general anesthetic and is a frequent occurrence during the administration of heavy sedation for procedures done nominally under “local anesthesia with sedation.” Under most conditions, the treatment is so routine as to be taken for granted by practitioners skilled in airway management. Manual support of the airway such as with an invasive endotracheal tube, application of a face mask over the mouth and nose and various other airway devices are employed, often with supplemental oxygen.
However, the use of a face mask or an endotracheal tube during surgical procedures has many drawbacks. The standard face mask places pressure on the chin and tends to collapse soft-tissue structures of the oropharynx. Additionally, air pressure that is applied through the face mask tends to equalize through the nose and the mouth, and therefore it can be counter-productive to the supporting of soft tissue to open the airway. Further, using a face mask usually requires one or two additional maneuvers, for example manual support of the chin, the insertion of an oral airway, etc., in order to remedy the problem. None of the invasive airway-support devices currently used in conventional anesthesia practice can be inserted in the conscious patient without causing significant discomfort and/or physiological disturbance.
Furthermore, recent advances in cosmetic surgery have made airway management significantly more challenging and have caused practitioners to accept conditions having a reduced margin of safety for their patients. In particular, laser procedures on the face are requiring heavier sedation leading more often to respiratory depression and obstruction while, at the same time, the increased fire hazard restricts the use of oxygen.
Obstructive Sleep Apnea (OSA), a syndrome defined in the early 1980's, is similar to drug-induced obstructive apnea in anatomy and treatment. The treatment of OSA has demonstrated that upper airway obstruction occurring during the sleep of afflicted patients can be relieved by the application of positive pressure through the nose alone. OSA differs from drug-induced obstructive apnea in that it is not drug-induced. Further, OSA typically does not have acutely disastrous consequences, but rather has long-term ill-effects and is a chronic condition.
A conventional method for treating a form of OSA is to provide a continuous positive airway pressure (C-PAP) through the nose in order to prevent an upper airway obstruction. Nasal masks are used, as are nasal insert devices. InnoMed Technologies, for instance, provides a device called NasalAire used to treat obstructive sleep apnea. The device includes conical shaped nasal inserts connected to gas delivery tubes which are connected to an air delivery system. A C-PAP generator is included, which automatically increases and decreases air flow rate to maintain a continues positive airway pressure. Furthermore, the device includes vent holes for venting CO
2
from the exhaling user.
FIG. 1
illustrates a conventional system for treating sleep induced apnea by providing a continuous positive airway pressure through the nose. As depicted in the figure, the patient
104
is fitted with tubing
102
. The tubing
102
receives airflow from a C-PAP machine and administers the airflow to the nose of the patient by tube branches
106
. An airflow delivery device
108
, having nasal inserts
110
is placed such that nasal inserts
110
are disposed within the nasal vestibules
114
of patient
104
. Airflow delivery device
108
additionally includes ventilation holes
112
, which provide ventilation for CO
2
from the user during expiration. Examples of such devices are disclosed in U.S. Pat. No. 5,533,506 to Wood, U.S. Pat. No. 4,702,832 to Tremble et al, and U.S. Pat. No. 5,134,995 to Gruenke et al., the entire disclosures of which are incorporated herein by reference.
What is needed is a method and apparatus for preventing complete airway obstruction of a patient when the patient is deeply sedated after induction of anesthesia.
What is additionally needed is a method and apparatus for enabling a patient to adequately respire at surgical levels of anesthesia without an invasive airway and manual or mechanized ventilation.
What is additionally needed is a method and apparatus for cost-effectively adding air to the anesthetic gasses for reducing the risk of combustion in the surgical field when using cautery or laser devices.
What is additionally needed is a method and apparatus for preventing leakage of the anesthesia to the operating room.
What is additionally needed is a method and apparatus for more accurately monitoring spontaneous respirations in a pressurized system.
What is additionally needed is a method and apparatus for preventing an airflow generator from excessively pressurizing an anesthesia circuit.
What is additionally needed is an apparatus that is: operably connectable to an existing anesthetic delivery apparatus; operable to prevent complete airway obstruction of a patient when the patient is deeply sedated after induction of anesthesia; and operable to enable a patient to adequately respire at surgical levels of anesthesia without an invasive airway and manual or mechanized ventilation.
SUMMARY OF THE INVENTION
It is the object of this invention to provide a method and apparatus that may comfortably be applied to the conscious patient prior to the induction of anesthesia to prevent airway obstruction and maintain oxygenation after the patient has become unconscious under the influence of anesthesia.
It is another object of this invention to enable a patient to adequately respire at surgical levels of anesthesia without an invasive airway and manual or mechanized ventilation.
It is another object of this invention to cost-effectively add air to the anesthetic gasses for reducing the risk of combustion in the surgical field when using cautery or laser devices.
It is another object of this invention to prevent leakage of the anesthesia to the operating room.
It is another object of this invention to more accurately monitor spontaneous respirations in a pressurized system.
It is another object of this invention to prevent an airflow generator from excessively pressurizing an anesthesia circuit.
Upper airway obstruction caused by a drug-induced depression of the central nervous system is preventable by applying positive pressure through the nasopharynx while leaving the oral cavity open to ambient pressure. The pressure differential thus created, splints the soft tissues out of the airway with a natural pressure relief valve through the oral cavity. The maximum pressure obtainable is consistently sufficient to relieve the obstruction, but is less than the 20 centimet
Lo Weilun
Noble Linda J.
Weiss, Jr. Joseph F.
Wenderoth , Lind & Ponack, L.L.P.
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