Geraldine B. Hunt, BVSc, MVetClinStud, FACVSc, PhD
Ninety years after his death, Halsted’s principles remain one of the most important creeds for the current-day surgeon. But his instructions are sometimes easier to remember than to follow, especially when dealing with very small or fragile patients. What does it really mean to minimize tissue trauma? How, exactly, does a surgeon handle tissues “gently” when surgery is intrinsically traumatic? This presentation will outline some important principles of surgery that have a real impact on outcome and provide practical hints as to how to better follow Halsted’s principles in your exotic patients.
- Strict asepsis during preparation and surgery.
- Good hemostasis to improve conditions for the procedure and limit infection and dead space.
- Minimize tissue trauma.
- Use good surgical judgement ensuring elimination of dead-space and adequate removal of material.
- Minimize surgery time through knowledge of anatomy and technique.
- Correct use of instruments and materials used.
Care and Handling of Tissue
Primum non nocere (above all else, do no harm). Minimizing tissue trauma through gentle tissue handling should always be a primary goal. The tissues are best cared for when we do the following:
- Avoid excessive blunt dissection.
- Avoid excessive traction.
- Handle tissues only when absolutely necessary.
- Separate only those tissue planes necessary for visualization or excision.
- Avoid repeated changes in retractor position.
- Do not allow retractors to tear or stretch tissue excessively.
- Keep the tissues moist with regular application of saline.
- Avoid exposure to irritant or inflammatory substances like talc, lint, urine, bile, or intestinal contents.
- Use appropriate instruments.
Although the consequences of profuse hemorrhage are understandably feared by surgeons and discussed with clients, effective hemostasis is taken for granted during most surgical procedures. In very small patients, even a trivial-appearing amount of hemorrhage can represent a relatively large volume of blood loss and it is clearly better avoided than controlled! Many small blood vessels are cut during even routine surgical procedures and a minority require intervention. Vessel retraction, platelet plugging, and coagulation usually occur promptly and, therefore, it is usually only the larger, visible vessels that require ligation. However, there are numerous potential sources of blood loss if coagulation is impaired for some reason. Ongoing bleeding in a patient with a coagulopathy may not just occur from obvious surgical sites but in the form of a slow ooze from all damaged surfaces, including those that have simply been handled during the procedure.
Hemorrhage is detrimental for a number of reasons. It may lead to hypovolemia and obscures the surgical field, increasing the risk of damage to local structures. Repeated attempts at clamp placement, ligation, cautery, or just swabbing the tissues leads to additional trauma. Ongoing hemorrhage slows the surgery and increases operating time, thereby increasing tissue trauma and bacterial contamination. To maximize effectiveness, reduce the risk of tissue damage, and facilitate natural clotting, hemostasis should be attempted in the following sequence:
1. Digital pressure. This stems the flow while enough platelets accumulate to form a plug, or a stable clot forms. Pressure should be applied for at least 60 seconds in cases of minor hemorrhage and up to five minutes for more serious hemorrhage. Avoid dislodging the developing clots when swabbing the area. Digital pressure may not be indicated in a patient with a very small circulating blood volume, in which case you should go straight to step two.
2. If simple digital pressure is ineffective, carefully apply a hemostat, using the tip of the instrument. The hemostats are left in position for at least five minutes, at which stage they may be released, cautery applied, or the vessel ligated.
3. If the bleeding point is deep within the tissues, within a body cavity, or in close proximity to a structure that might be damaged by hemostats (such as the facial nerve during total ear canal ablation or the ureter during ovariohysterectomy) further pressure may be applied by packing the cavity tightly with surgical sponges. Sponges are packed on top of one another and held in position until blood stops oozing through the fabric. The packing is left in place for at least 5–10 minutes. It is helpful to use a clock or stopwatch, as time passes slowly under these circumstances! Always perform a sponge count to ensure that sponges are not retained.
4. For a final check of a wound or body cavity, flood the area with sterile saline. Hemorrhage appears as a tendril of blood rising like chimney smoke from the bleeding point, allowing careful application of thumb forceps or a hemostat. Pressure and other physical effects of the saline such as cold temperature will also sometimes stop the bleeding.
The instruments available to the surgeon have been developed for very specific scenarios and the chances are that they were not designed with reptiles and birds in mind! Most surgeons use a small number of key instruments during the course of everyday practice and there are some instruments that are appropriate regardless of which species they are used for. Gentle tissue handling is facilitated by choosing the appropriate instrument for each task; reducing the number of times the tissues are grasped, released, and grasped again; and ensuring the instruments are sharp, the locking devices reliable, and the jaws close smoothly and effectively. Good retraction and good lighting are essential to minimize tissue trauma. Stay sutures should be used in situations where handheld or self-retaining retractors are not appropriate. In some instances, the tissues are too fragile to use surgical instruments (e.g., mediastinum, bladder wall).
Saline-soaked swabs and sponges are used to keep tissues moist, protect them from retractor blades, absorb blood and body fluids, swab the wound to keep it clear of blood while the surgeon is working, and for packing when hemostasis is required. The surgeon or their assistant should always keep count of the number of swabs opened and make sure the count matches before the surgical wound is closed, as retained swabs have been reported in many locations including the thoracic and abdominal cavities, lumen of the stomach, airway, and soft tissues following fracture repair or major soft tissue reconstruction.
Wound lavage should be used after lengthy procedures or those in which contamination is known to be present. Vigorous lavage using warm, sterile saline dislodges bacteria, lint from surgical sponges, talc from surgical gloves, blood clots, intestinal contents, urine, and other foreign or irritant material. Repeated flooding of the site with saline, followed by suction, can be used to confirm whether hemorrhage is still occurring or if there is ongoing air leakage following a lung lobectomy or biopsy, or biliary tract surgery. Lavage is most beneficial when appropriate volumes of saline are used (dilution effect), with physical dislodgment of debris by pulsatile application of hydrostatic pressure.
Some form of surgical suction is essential for many of the procedures we perform in order to remove contamination and tumor cells, clear the surgical site of blood to improve visualization, allow retrieval of saline used to flush away blood and debris, moisten tissues and identify bleeding points, and permit suctioning of aerosolized gases liberated during electrocautery. Gentle application of a fine suction tip is a very effective way to separate organs, break down adhesions and establish tissue planes.
There are many different types of retractor available, but few are delicate enough for very small patients. Judicious use of stay sutures can be a lot less traumatic than having your assistant tugging on a Senn retractor, and indeed, can take the place of an assistant. The Lone Star retractor (Lone Star retractor, Lone Star Medical Products, Stafford, TX) is very useful, eliminates the need for an assistant to hold retractors in many instances, and can exert constant force on tissues. Moistened sterile Q-tips, used in the fashion of chopsticks, or in place of grasping instruments, are a great way to move tissues around without damaging them and have the added advantage of absorbing blood and fluid, thereby improving visualization.
The Surgical Assistant
Effective utilization of a surgical assistant does, however, contribute greatly to a successful outcome. The role of the assistant includes managing the surgical table, assisting with surgical retraction, ensuring diagnostic samples are not lost, and keeping count of surgical sponges. Effective engagement of the surgical assistant ensures the surgery proceeds efficiently and with minimal interruptions.
Surgical Lighting and Magnification
You cannot perform surgery safely if you cannot see! Ideally, an operating room should be equipped with at least two ceiling-mounted lights capable of focusing on the surgical site. The lights should not emit too much heat, should not cast shadows, and should allow you to accurately interpret colors. You should be able to either apply sterilized light handle covers or sterilize the handles themselves to control the light at your convenience. The two lights should have articulated attachments that allow them to be directed towards the patient at virtually any angle. They should be capable of moving independently. One light is used as a “primary” light (usually centered above the surgeon) and the other is a “secondary” light that is directed at an angle and often moved during the course of the surgery. The surgeon or their assistant should take note of changes in lighting during the procedure and ensure the lights are positioned to avoid them being obscured by the surgeon or assistant. This is especially important when working in body cavities. Time should be taken at each stage of the surgical procedure to ensure that the lighting is optimal. Poor visualization during surgery is often the result of poor light position.
Intraoperative illumination may also be achieved with surgical headlights. These are mandatory for microsurgery and delicate procedures in very restricted surgical fields. Likewise, fine detail work in tiny patients will be greatly facilitated by some form of magnification, even if you have great vision. Operating loupes, and minimally invasive cameras can provide this magnification. Loupes are great if you have them set up specifically for your eyes and use them regularly. If you only dust them off once every 12 months then they will be uncomfortable, hard to focus through, and feel like they are in the way. They need to become second nature to help rather than hinder you, but you and your patients will appreciate the results.