Application Of Pressure Bladder Indicator In Clinical Intravertebral Anesthesia

To inject the anesthetics into the intravertebral lacuna such as subarachnoid space or epidural space to block the conduction by spinal nerve can produce anesthetic effects and intravertebral anesthesia is one of the most popular anesthesia methods. Intravertebral anesthesia is divided into epidural anesthesia, combined spinal-epidural anesthesia and subarachnoid block according to the difference space of the injection of anesthetics. Intravertebral anesthesia has a better effect to inhibit stress reaction caused by operation and anesthesia and can apply postoperative analgesia. On the other hand, the incidence of deep venous thrombosis may reduce and the function of intestinal tract may recovered by promoting enterocinesia with intravertebral anesthesia. The analgesia effect of epidural anesthesia by the spinal nerve root block can meet different requirements in various operations. Combined with epidural anesthesia and subarachnoid anesthesia, combined spinal-epidural analgesia has the advantages of short onset time and complete nerve block. Epidural puncture is the key technology of successful intravertebral anesthesia. The tissue or nerve may be injured by misoperation and misjudging, which may bring about serious effects ang even threat the patient's life. The successful intravertebral anesthesia has been depending on subjective judgment of the doctor since the invention of intravertebral anesthesia at the end of 19century. The judging methods include breakthrough of yellow ligament, elimination of resistance by pushing the glass syringe (figure 1)and bubble compression test. There is no objective index and instrument to judge whether epidural paracentesis is successful. The traditional methods will be influenced work by many factors including the doctor's subjective feeling, the structure of epidural space and the changes of the puncture interspace. An objective device for the judgment of successful epidural puncture to reduce the complication of intravertebral anesthesia is necessary.The aim of the study was to observe the feasibility and accuracy of the new patent of pressure bladder indicator in clinical intravertebral anesthesia. According to the principle of previous test of positive pressure balloon(figure 2), the pressure bladder indicator in the paper was to use the pressure bladder to determine the tip's pressure unremittingly. The pressure bladder indicator was refitted by a 5 ml syringe according to the principle of the test of positive pressure balloon(figure 3). There was a lateral aperture in front of the needle about 1cm at the sidewall covered with a rubber membrane.3-5 ml physiological saline was extracted and connected with the end of the puncture needle. Across the subcutaneous soft tissue, the puncture needle reached the ligament and other compact tissue. Meanwhile, push the syringe piston(figure 4). The tip suffered the resistance of the compact tissue and the pressure in the syringe cylinder increased. And the rubber membrane expanded to become a pressure bladder of liquid about 1.0-1.5cm in diameter. The pressure bladder would keep expansion due to the frictional resistance between the syringe cylinder and piston, which prevented the syringe piston retreat automatically. At the same time, the puncture needle went on with two hands(figure 5). The pressure of the tip decreased suddenly while the needle broke through the ligamentum flavum. Liquid in the bladder outflew quickly and the pressure bladder flatted quickly too, which provided a viewable signal of successful puncture. This device monitored the whole puncture process automaticly and threw off the subjective judgment of anesthesiologist. And this device elevated security of intravertebral anesthesia and reduced the risk of human error. In clinical teaching, the teacher couldn't judge the accuracy depth of puncture needle without feeling. However, the bladder indicator could be seen by everyone. The pressure bladder indicator adopted automatic monitoring techniques for the first time.And it decreased the dependency of operating experience and reduced the risk of misjudgment and the hidden trouble of malpractice. The doctor can operate with bimanualness unremitting in the process of puncture. It is a revolutionary technological progress in epidural anesthesia domain.With the improvement of people's living standard, the quantity of elderly patients increased day by day. It was proved that intravertebral anesthesia had some effects on the circulatory function of elderly patients. However, the circulation system of elderly patients maintained relatively stable during operation. Intravertebral anesthesia was more suitable for elderly patients with cardio-cerebrovascular disease. The incidence of POCD caused by anesthetics decreased during intravertebral anesthesia. Because of the hardened vessel wall of elderly patients, the puncture must be done softly to reduce the probability of hemorrhage injury and elevate achievement ratio. The supraspinal ligament and interspinal ligament lost elasticity because of calcification which led to difficult puncture with intervertebral space narrow and kyphosis. So lateral epidural puncture was better for elderly patients and the application research of pressure bladder indicator in lateral epidural puncture on elderly patients was described in part II of this study.Part I The feasibility and application effect of the pressure bladder indicator in clinical intravertebral anesthesiaObjective To determine the pressure of epidural space and the pressure bladder. To observe the feasibility and application effect of the pressure bladder indicator in clinical intravertebral anesthesia.Methods1.120 patients(18?60 yeas old) were selected with Tio-L3 epidural puncture and no contraindication of epidural puncture by conventional epidural puncture. When the puncture succeeded, the pressure sensor was connected with the end of puncture needle by triplet to measure the pressure of epidural space.2.120 pressure bladder indicators were randomly assigned, and 5ml physiological saline was extracted by each indicator. The pressure sensor was connected with the front of the indicator, and then push the syringe piston about 2 ml to make the bladder inflated. Observe the pressure reading lasting for 5 seconds with no changes and record the working pressure of the bladder.3.400 patients who would undergo intravertebral anesthesia with no contraindication of epidural puncture were randomly divided into pressure-bladder group(P) and control group(C)(n=200 each). All patients were operated by straight epidural puncture. In group P, the pressure bladder indicator was connected with the end of the puncture needle. When the needle passed through the skin and subcutaneous loose tissue, the syringe piston was pushed to make the bladder expand. In the continuous process of epidural puncture, if the tip of puncture needle got to the epidural space, the pressure bladder flatted rapidly because of the delivery head between the bladder and epidural space. Observe and record the patients with successful indication and the patients were tested by the traditional judgement methods again. In group C,epidural puncture was tested by traditional judgement methods.Record the operating time, incidence of complication and achievement ration and observe the anesthesia effectiveness.Results1. The pressure of epidural space was (9.8±4.3) mmHg.2 patients were rejected from this study because of the unsatisfactory effects and hemorrhage in the process of puncture.2. The pressure of the bladder was (72±4) mmHg after pushing 2 ml liquid to inflate the bladder.3. The application of the bladder indicator:In group P,200 patients were all indicated successfully by bladder indicator. The coincidence rate was 100%.197 patients were indicated immediately, and 3 patients with delayed indication were indicated immediately by changing the direction of puncture needle. In group C,1 patient failed in epidural catheter insertion after successful puncture tested by tradional methods. The puncture needle entered the subarachnoid space by mistake with 3 patients.Conclusion1. The epidural space was of low positive pressure and the pressure was close to central venous pressure. The clinical negative pressure maybe only appear in the instant when the needle reached the dura mate of spinal cord.2. The pressure of the tip decreased quickly while the needle broke through the ligamentum flavum during the puncture. The bladder flatted immediately when the liquid in the bladder outflew rapidly. The coincidence rate comparing the method of pressure bladder indicator with traditional methods was 100 percent.3. It concluded that the device with a simple operation provided a brake signal to suggest the needle's position in the puncture accurately. This may reduce the risk of intravertebral anesthesia by elevating the success rate and reducing the puncture complication. The pressure bladder indicator with the advantages of simple operation and accurate judgment has great value in clinical application.Part ? Application research of pressure bladder indicator in lateral epidural puncture on elderly patientsObjective To investigate the application of pressure bladder indicator in lateral epidural puncture on elderly patients.Methods1. One hundred and twenty elderly patients(ASA ???,75-92 years old)were preparing to undergo orthopedic operation in lower extremity. The lumbar of all patients had calcification with different degrees.2. After routine disinfection, all patients were operated with lateral epidural puncture. When the needle passed through the skin and subcutaneous loose tissue, the syringe piston was pushed and the bladder was inflated. Observe the changes of the pressure baldder during the whole process of epidural puncture. If the tip of the needle met the bone, the operator should withdraw the needle to the subcutaneous tissue and refill the bladder. It showed that the needle got to the epidural space when the bladder flatted rapidly. At the same time, traditional methods were used to judge whether the needle had reached the epidural space. The anastomoses ratio of the two methods was calculated.ResultsAmong the 120 elderly patients, the anesthesia methods of 3 patients were changed with general anesthesia because of abortive epidural puncture. The other 117 patients all achieved successful puncture with the accurate indication of pressure bladder indicator in lateral epidural puncture. The rate of correct indicator was 100 percent.ConclusionThe pressure of the needle tip decreased suddenly while the needle broke through the ligamentum flavum. The bladder flatted immediately because of the different pressure between the bladder and epidural space, and the liquid in the bladder outflew rapidly. It provided a visual signal of successful puncture. The pressure bladder indicator with the advantages of simple operation and accurate judgment is of great value for elder patients in clinical application.