Anesthesia in Pediatric Orthopedics

Anesthesia in children has advanced dramatically during the past two decades. This improvement is due to subspecialization, new techniques, a focus on pain management, and preparing children psychologically.

Preoperative Problems

Respiratory infections The younger child has an average of four or five upper respiratory infections (URIs) per year. These infections complicate operative planning. Such infections pose operative hazards by increasing the risks of laryngospasm, bronchospasm, and coughing. Coughing during inductions increases the risks of regurgitation and aspiration. These problems can lead to a reduction in oxygen saturation during and after surgery.

Elective surgery
If the child has an upper respiratory infection, cancel surgery if the child is less than a year of age, if signs of viremia or bacteremia are found, if scheduled for a long or complicated procedure, or if findings suggest a lower respiratory component is present.

Allow about two weeks after cessation of symptoms following a URI and 4–6 weeks after a lower respiratory infection.

Oral intake restrictions

Infants under 6 months Allow feeding breast milk or formula to 6 hours before surgery and clear liquids to 3 hours before surgery.

Older infants and children Allow feeding to 8 hours before surgery and clear liquids until 3 hours before surgery.

Perioperative Fluid Management

Fluids Management usually requires replacement and maintenance. Maintain using a balance salt solution (BSS) such as lactated Ringer’s solution.

Fluid requirement Calculate fluid requirements on the basis of 4 ml/kg/hr for the first 10 kg of body weight, plus 2 ml/kg/hr for the next 10 kg and 1 ml/kg/hr above that.

Estimated blood volume for children Calculate the EBV in ml/kg at 90 for newborns, 80 for infants in first year, and 70 for older children.

Indications for intraoperative blood replacement In the healthy child, replace acute volume losses of 25–30%. The most reliable signs of hypovolemic shock in children are a tachycardia, diminished pulse pressure, and prolonged capillary refill time. Generally, replacement is indicated if the hematocrit drops below 21–25%.

Special Anesthesia Problems

Certain diseases carry particular risks requiring special consideration.

Meningomyelocele Start blood replacement early.

Myopathies This group of patients presents special risks. They should be referred to the anesthesiologist in advance of the procedure for an evaluation, which often includes an EKG, chest x-ray, and pulmonary function studies. These patients are prone to develop a malignant hyperthermia syndrome, cardiac rhythm dysfunction, and postoperative respiratory problems.

Cervical spine abnormalities
Be concerned if the patient has dysproportionate dwarfism, Down syndrome, Goldenhar syndrome, Klippel–Feil syndrome, systemic JRA, or neck trauma. These patients should have preoperative evaluation and require special precautions, especially during induction.

JRA Children may have TM joint ankylosis, cervical spine stiffness, and/or instability.

Latex allergy Latex allergy includes a spectrum of dermatitis, rhinitis, asthma, urticaria, bronchospasm, laryngeal edema, anaphylaxis, and interoperative cardiovascular collapse.

High-risk patients include those with spina bifida, and those with repeated procedure and exposure to latex and who show varied allergic reactions.

Current status Suspect and send for preoperative anesthesia consultation. Plan a latex-free surgical environment during the operation.

Anesthetic Risks

Anesthesia is generally a greater risk than most orthopedic procedures. Still, the risk of anesthesia is small. Fatal complications of anesthesia occur in 3–4 per 100,000 procedures. Most complications can be prevented by close monitoring, maintaining adequate oxygenation, and careful control of the level of anesthesia. Greater sophistication and cooperation between the surgeon and anesthesiologist [A] can reduce these risks. Complications include laryngeal and bronchospasm, aspiration, and cardiac arrhythmia and arrest.

General anesthesia is the standard for infants. The induction technique is determined by the age of the child and the planned procedure. Rectal induction is used for some infants (over 6 months) and for simple procedures such as spica cast changes. Intervenous induction is appropriate for the adolescent when the IV is placed before the procedure. In children, induction is often provided by inhalation anesthesia. The IV is then started quietly, with the child asleep. The preferred sites are hand or foot, antecubital veins, scalp, or external jugular vein. Avoid the femoral vein. In infants with small veins and abundant subcutaneous fat, IV insertion can be very difficult.

Regional anesthesia Occasionally, local or regional anesthesia will be used for upper extremity fracture management. This may be achieved by a hematoma block, intravenous anesthesia, or axillary or peripheral nerve blocks.

Sedation Some procedures are planned with sedation only and anesthesia ready if needed. This is suitable for early spica cast application for femoral shaft fractures, dressing changes, or minimally painful procedures.

Blood Replacement

Order blood preoperatively if replacement is a reasonable possibility. Generally, major procedures done without a tourniquet may require replacement. Families are extremely concerned about the risk of AIDS when the possibility of transfusion is considered. The risk depends in part on the competence of the blood bank. Statistically, when transfused, the risk of receiving infected blood is roughly equivalent to the risk of receiving the anesthetic. Special situations may complicate blood replacement. Transfusions may be restricted by religious beliefs or the fear of AIDS. Minimizing blood loss may be necessary in difficult cases, such as spinal fusions and limb salvage procedures. Hypotensive anesthesia may be adequate. The mean blood pressure is maintained between 50 and 60 mm. Hypothermia is seldom indicated in orthopedics. Hemodilution is a technique by which blood is removed just prior to surgery and replaced at the end of the procedure. Finally, autologous blood donation and cell-saving techniques are becoming more widely available. Blood substitutes will be available in the future.

Postoperative Pain Management

Postoperative pain management can begin before the procedure with placement of an epidural catheter. Epidural blocks are contraindicated when there is a need to monitor postoperative pain, as when a compartment syndrome is a possible postoperative problem. Problems with epidural blocks include itching and urinary retention. Consider injecting marcaine into the wound edges at the end of the procedure to provide comfort in the early postoperative period. Patient-controlled analgesia (PCA) is a valuable technique for the child over 7 years of age. Morphine or meperidine are useful agents. Provide oral pain control by codeine or oxycodone.

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