C-Sections: Anesthesia And Surgery
If you are performing pet C-sections, follow these tips for a safe and speedy operation.
Phil Zeltzman, DVM, Dipl. ACVS
This article first appeared in the August 2013 issue of Veterinary Practice News.
We continue describing our steps for a happy C-section. [See Part 1 here]. In this article, we focus on anesthesia and surgery. Our goals: safety and speed.
Melissa Goodman, DVM, board-qualified in the American College of Theriogenologists at Veterinary Reproductive Services in West Chester, Pa., skips premedication, and prefers masking patients down. She uses the smallest possible dose of propofol only if needed, e.g. in brachycephalic and fractious patients.
When giving drugs to the dam, you are indirectly giving them to the babies. Many drugs are rapidly carried through the placental barrier and consequently affect the offspring. This may make resuscitation efforts more difficult.
For example, acepromazine, ketamine and atropine can flow through the placenta, so they should be avoided. Glycopyrrolate, if needed, is a better choice than atropine.
Choosing an anesthesia protocol that is safe for a caesarean patient is tricky at best. Because hypoxia is a concern for the patient and the neonates, pre-oxygenation for five to 10 minutes is an important precaution.
Patients are then intubated and placed on isoflurane or sevoflurane and oxygen. Pregnant patients typically do not require as much inhalant anesthesia, so a conservative gas percentage will help the mother and the babies.xOur goal should be to maintain uterine blood flow and therefore maternal oxygen delivery.
Since these cannot be measured simply, our objectives should be to keep heart rate, volemia and blood pressure within normal limits. In addition, patients will often take shallow breaths, so we may need to "bag" them to ensure proper gas exchanges.
It is important to remember that dorsal recumbency and the weight of the uterus may cause aorto-caval compression, further worsening maternal hypotension.
Overall, the art of analgesia and anesthesia enables us to keep pregnant patients at a plane of anesthesia that requires as few drugs as possible while ensuring their safety, as well as their offsprings' well-being.
The double goal of a C-section is safety and speed. With experience, "Only a few minutes should go by between anesthesia induction and the actual delivery," insists Margret Casal, DrMedVet, Ph.D., Diplomate of the European College of Animal Reproduction, of the University of Pennsylvania School of Veterinary Medicine.
However, before induction, take two minutes to verbally go over the procedure. Clarify each person's responsibilities: anesthesia, attaching ECG clips, scrubbing, resuscitation—even who will tie your gown.
This is what many human surgery teams do, and this communication tool has been shown to decrease complication rates and increase survival.
A great time saver is to induce and intubate the (already clipped) patient on the OR table, rather than in the treatment room. As long as the mother lets you clip her thoroughly, this will shorten time under anesthesia even more.
While mom is being pre-oxygenated, induced and scrubbed, a technician should be opening the surgical pack, drape and other supplies. Meanwhile, the doctor can scrub, gown up and glove up. Some colleagues actually scrub in prior to induction.
Forget Ms. Smith's anxious phone call, forget finishing your doughnut and forget checking your email. The doctor's single mission is to be ready to drape and cut as soon as mom is scrubbed.
There are three main surgical techniques: C-section only, traditional C-section and spay, and "en bloc" spay and C-section.
C-section only: Surgery starts as a standard laparotomy, usually from the umbilicus to the pubis. Be very careful not to cut into the distended uterus by accident. One tip borrowed from human surgery: Consider using a sterile pair of bandage scissors. The blunt tip makes it less likely to injure the gravid uterus when cutting the linea alba, or cutting fragile fetal tissues when cutting into the uterus.
Once the uterus is gently exteriorized—i.e. by lifting rather than pulling—laparotomy sponges can be placed to prevent uterine fluids from contaminating the abdomen.
A hysterotomy is performed in the uterine body. Each fetus is carefully "milked" from each horn through the opening in the uterus.
Each neonate is removed from the surgical field to prevent contamination of the abdomen. The amniotic sac is promptly removed. The umbilical cord is clamped with small hemostats, then cut. The baby is then handed off aseptically to an assistant to start resuscitation. The placenta may need to be manually separated from the uterine wall.
The maneuver is repeated until all babies are removed, including one that may be stuck in the pelvic canal. The uterus is sutured with 3-0 or 4-0 absorbable suture material (polyglactin 910, poliglecaprone 25), in a full thickness, appositional (simple continuous pattern) or inverting (Cushing pattern).
Goodman prefers using simple interrupted gut sutures in a double layer closure. "Polydioxanone can cause granulomas," she explains.
After palpating the entire uterus to make sure nobody's been forgotten, standard lavage and "hemostasis check," abdominal closure ensues. It may be a good idea to use an intradermal pattern to avoid complications with exposed skin sutures or staples.
Oxytocin may be given at this time if needed to help with uterine contraction, hemostasis and milk "let down."
Traditional C-sectionand spay: If the clients have elected to have their pet spayed, then a standard ovariohysterectomy (OHE) is performed once the C-section is completed.
Both our reproduction specialists say that spaying at the time of a C-section will contribute to hypovolemia and may increase the risk of hemorrhage. In turn, it will make the recovery tougher.
"En bloc" spay and C-section: You may want to consider this "new" technique, which was actually first described almost 20 years ago.*
Since time is of the essence here, the OHE is performed first. The ovarian and uterine pedicles are double or triple clamped. Large vessels are also clamped. No ligatures are placed yet. The entire uterus is removed en bloc, and handed off aseptically to the recovery crew.
They will open the uterus and recover the babies, while the practitioner focuses on ligating, inspecting and closing up.
With experience, this very elegant technique can significantly speed up a C-section. It also may increase the babies' survival rate since there is less risk of hypoxia.
Clean the incision only with warm water. Antiseptics in that area may inhibit the babies from nursing.
A safe anesthesia protocol and a swift C-section are keys for a happy outcome. Clear communication, in order to define each person's roles, will help with efficiency.
The next step is to take appropriate care of the neonates, which we will discuss in our final installment here.
- Consider scrubbing before induction
- Pre-oxygenation patients for 5-10 minutes
- Before induction, take 2 minutes clarify each person’s responsibilities
- Induce and intubate the (already clipped) patient on the OR table
- Consider an “en bloc” spay and C-section for your next patient.
* MA Robbins and HS Mullen. “En bloc ovariohysterectomy as a treatment for dystocia in dogs and cats.” Veterinary Surgery 1994, Vol 23, N 1, p. 48-52..
Kelly Serfas, a certified veterinary technician in Bethlehem, Pa., contributed to this article.