Ultrasound - The Second Eye of the Anesthesiologist

Ultrasound - The Second Eye of the Anesthesiologist

Past and present of the anesthesiology department

Regarding Anesthesiology, i once listened to a chief physician who has been working in the clinic for more than 20 years: There is no department of Anesthesiology in the 1990s. The status of anesthesiologists at that time was also relatively low. The surgeon will perform his own anesthesia, which is inefficient and lack of supervision, resulting in a greatly reduced success rate of surgery. At that time, the traditional nerve block  was the main method in the procedure. The anesthesiologist would choose the appropriate puncture point according to the actual situation, but the whole operation was performed under non-direct view, and the puncture was affected by many factors such as age, weight and disease. The impact is very different. Thus, The anesthesiologist's technique and experience are very demanding, a slight deviation caused a thousand miles difference.

With the advancement in medical technology, neuroanaesthesia and vascular puncture techniques have achieved "precise anesthesia" under ultrasound-guidance. Ultrasound has become the "second pair of eyes" of anesthesiologists. The nerves and blood vessels are clear and visible, improve the accuracy of anesthesia puncture effectively , the dose of medication used is reduced and thus reducing the anesthesia complications. 

History of  ultrasound in Anesthesiology

Regarding the origin in between ultrasound and anesthesia, La Grange was the first to report ultrasound-guided nerve block in 1978. They used Doppler flow  ultrasound to perform supraclavicular brachial plexus block. These early reports were not used clinically because the anatomy of ultrasound observations is still limited. However, a decade later, dramatic changes have occurred, and ultrasound have been used for regional anesthesia in recent years, a considerable improvement compared with few years ago.

Comparison between Ultrasound, CT and X-ray guided puncture effect

X-ray lacks of information on soft tissue and it is radioactive, thus it has never been widely used as a first-line puncture guidance method. CT is also one of a guiding technique that can be used, but there are defects such as relatively complicated operation technique, radioactivity,inability to move and etc. Therefore, the application range is very limited.  

Compared with X-ray, CT and other imaging techniques to guide nerve block, ultrasound-guided technology has the following obvious advantages:

1. High resolution, modern high frequency which can distinguish the anatomy of most peripheral nerves. 

2. The soft tissue contrast resolution is extremely high, and it can visualize the muscles, blood vessels , nerve and other surrounding structure clearly. 

2. Real-time, ultrasound imaging can clearly show the process of the puncture needle.

3. Convenience, biopsy under ultrasound guidance is fast and convenient, one puncture can be completed in only one 3-5 minutes

4. No radioactivity.

5. Bedside operation

The real-time ultrasound can clearly show the anatomy of most peripheral nerves and their branches. Ultrasound can also display the position of the needle in real time, which greatly improves the accuracy of the puncture, obtains better therapeutic effect, greatly reduces the occurrence of complications.

Required equipment

The visualization  of nerves requires higher-frequency, high-resolution ultrasound equipment. The following principles should be considered when selecting equipment to guide nerve block (taking the Vinno product as an example):

1. With a variety of probe types, at least two probes with a center frequency of about 7MHz and a center frequency of more than 10MHz should be used. Broadband probes are preferred, and the choice of wideband probes is preferably at 10-14MHz and 5-10MHz. For obese patients and deeper nerve and ganglion blockades, lower frequency probes are used, so 3.5-5MHz probes must also be configured.

2. Because the muscle ,tendons and other connective tissue structures around the nerve have obvious anisotropic effects, in order to reduce the anisotropic effect on image quality, the selected ultrasound instrument should have a beam tilting function.

3. Ultrasound machine should be light and compact, easy to place and move between the operating room.

4. Should have a more sensitive color and spectral Doppler function in order to identify the vascular structure around the nerve.

(Vinno high resolution color blood flow)

5. The device should have a hard disk with sufficient capacity to store images and real-time images. It also has the ability to directly store and export images and movies in multiple formats such as TIF, JPG, BMP and MPG4.

Wide application of ultrasound in anesthesiology

In clinical anesthesiology, patients with obesity and spinal deformity are often encountered with difficult spinal anesthesia . At this circumstance, the intervertebral space can be located by ultrasound. The distance from the skin to the epidural space can be predicted so the puncture site and direction can be determined appropriately. Thus, the procedure is simple, and safe.

Second, ultrasound can be widely used for targeting and positioning. For instance, in ultrasound-guided nerve block, the target nerve that needs to be blocked can be visualized by ultrasound imaging, and same goes to the important blood vessels and tissues around the nerve, as to ensure the accurate diffusion of local anesthetic around the nerve during nerve block. At the same time, it avoids damage to important blood vessels and tissues around,reduces the incidence of complications. It is not only widely used in orthopedic surgery, but also in many open surgery, such as abdominal transverse plane block. The application of these technologies not only reduces the amount of general anesthetic drugs, but also reduces the medical expenses of patients, and provides patients with good postoperative analgesia.

Again, the usage of ultrasound in targeting is also widely used in various assessments such as intra-operative emergency diagnosis. In difficult airway assessments, ultrasound can clearly show the apical apex to the mid-airway tissue, thus predicting airway conditions in obese patients.

In addition, ultrasound can accurately detect gastric retention, minimize the occurrence of reflux aspiration, and determine the signs of bleeding in the chest, abdomen and pericardium during surgery, pulmonary embolism, pneumothorax, and even cardiac arrest.

With the continuous exploration and discovery of ultrasound function,it is not only provide safer and more effective anesthesia,but also provide patients with more comfortable medical services.

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