Home-Amb-Card-Crit-Neuro-OB-Orth-Pain-Ped-Reg-Tran-Vasc-Misc
Introduction
Surgical emergencies in children range
from absolutely urgent to semi-elective, depending on the underlying problem.
From an anesthetic standpoint, management of the patient may range from
care of a critically ill premature infant to that of an otherwise healthy
teenager. Understanding the differences in anatomy, physiology, and pharmacology
of the different age groups, along with the underlying pathology of the
surgical emergency will be the focus of this lecture.
Neonatal
Period--Incarcerated Inguinal Hernia
Disease
State
Anesthetic
Considerations
Preoperative
Assessment
Intraoperative
Management
Postoperative
Care
The incidence of an indirect hernia in a full-term newborn is 3.5-5%, while the incidence in preterm infants is considerably higher, up to 30%. The greatest risk from a hernia is the development of intestinal incarceration and strangulation, with a reported incidence of up to 30% in infants less than 2 months of age. In 70% of incarcerated infant hernias, it may be possible to reduce the hernia and to convert an emergency operation to a semi-elective procedure. Because of a much higher complication rate following emergency surgery (22%) compared with elective surgery (1.7%), it is preferable to repair the hernia in an elective fashion.
The postconceptual age PCA (gestational age plus the postnatal age) is important in considering the postoperative risks of apnea due to general anesthesia or sedative drugs. Preterm infants who are less than 55 weeks PCA are at an increased risk of apnea following general anesthesia. Very small and very ill preemies may require postoperative ventilation and should have an ICU bed available. The metabolic and fluid status of the child should be assessed. A very small infant should not be NPO for longer than 2-3 hours without consideration of intravenous fluids. These infants are at risk for hypoglycemia, and appropriate glucose administration (5-8 mg/kg/min) should be provided both preoperatively and intraoperatively, usually with D-5 0.2 NS at 4 ml/kg/hr.
Laboratory studies that are ordered should reflect the underlying illnesses of the child and the surgical procedure. Most neonates having their hernia repair would benefit only from a preoperative hematocrit. Depending on the individual practice of neonatologists, many ex-preemies are allowed to have fairly low hematocrits (i.e., <28) without being prophylactically transfused. While anticipated blood loss should be minimal, anemia in the preterm infant is a predictor of postoperative apnea, regardless of the postconceptual age.
Regardless of the anesthetic technique chosen for surgery, the operating room environment should be prepared with appropriate monitoring equipment and temperature regulation. The
neonate will rapidly lose heat to a cold environment. Ambient room temperature should be increased to 80-85 degrees. Forced air warmers can dramatically improve the ability to maintain the neonate’s body temperature at a normal or even elevated level. Circuits, ventilators, and monitors are available for neonatal anesthesia.
Successful general anesthesia includes appropriate airway management, avoidance of hyperoxia to prevent retinopathy of prematurity, judicious fluid management, and avoidance of significant myocardial depression from the inhalation agents. In MAC-equivalents, all the inhalation agents are myocardial depressants in neonates. All inhalation agents also predispose to postoperative apnea in the preterm infant, and intravenous caffeine (10 mg/kg) should be given to minimize this risk.
Depending upon factors such as the size of the hernia and the speed of the surgeon, regional anesthesia may be an option for this type of surgery. This is particularly appropriate if the hernia can be reduced, and the case can be done semi-electively. Both spinal (0.6-0.8 mg/kg tetracaine with epi) and caudal-epidural (1 ml/kg 0.375% bupivacaine with epi) anesthesia have been used in order to avoid general anesthesia and its attendant risks.
Analgesia should be provided. This can be done by the surgeon with a "splash technique" which involves bathing the wound with local anesthetic for 2-3 minutes prior to closure. Alternatively, the surgeon can infiltrate the ilioinguinal and iliohypogastric nerves prior to closure. The typical analgesia provided according to the recent survey of pediatric surgeons is a bupivacaine block (30%) and/or acetaminophen (30%).
All former preterm infants less than 55 weeks PCA should be monitored at least 24 hours for the risk of postoperative apnea.
Infancy--Pyloric
Stenosis
Disease
State
Anesthetic
Considerations
Preoperative
Assessment
Intraoperative
Management
Postoperative
Care
Hypertrophic pyloric stenosis is the most common surgical disorder producing emesis in infancy. It occurs in approximately 1/300 live births in the USA with an increased incidence in first born males. Parents with the disorder have a higher incidence of children born with pyloric stenosis.
The musculature of the pylorus is thickened and edematous. Obstruction usually develops by 2-4 weeks of age. Emesis is usually projectile because of the high pressure generated by hypertrophied gastric muscles.
Diagnosis is often made by history and physical exam. An "olive" is sometimes palpated in the epigastrium just to the right of the midline. When the diagnosis cannot be made by exam, barium UGI or an ultrasound may be used to confirm the diagnosis. While many
institutions are using ultrasound as the first diagnostic tool, recent cost-analysis shows the UGI to be more cost-effective.
Preoperatively, the child should be assessed for signs and symptoms of dehydration. While it is becoming uncommon to see severe dehydration and malnutrition, it does occur. On admission, one may see tachycardia and hypotension which accompany significant dehydration. Other signs include decreased skin turgor, sunken fontanels, poorly perfused extremities, and lethargy.
In the case of extreme (15-20%) dehydration, a fluid bolus of 20 ml/kg of isotonic fluid should be administered for initial volume resuscitation. For mild to moderate dehydration, D5-0.45 NS with 20-40 mEq KCl/l is often used at a rate 1.5-2 times maintenance until volume is restored.
A second consideration involves the electrolyte status. Many infants present with some degree of metabolic alkalosis, hypochloremia, and hypokalemia. There may be a paradoxical aciduria which implies a significant potassium deficit. These electrolyte abnormalities should be mostly corrected prior to surgery. Recognizing the push from insurance companies to rapidly diagnose, treat and discharge these infants, remember that pyloric stenosis is a medical emergency and not truly a surgical emergency.
These children should arrive in the OR with an IV. Standard monitors are placed. The stomach should be emptied while the child is awake, as there is often residual stomach contents and barium. This does not guarantee that the stomach will be empty, however, and a rapid sequence induction should be performed following atropine administration.
A recent survey of anesthetists in the UK revealed that only 66% performed intravenous inductions, and of those, only 56% used cricoid pressure. There is also some controversy regarding the appropriateness of awake intubations in this situation. A recent study comparing awake, rapid-sequence, or modified rapid sequence inductions demonstrated faster, more successful intubations when the babies were paralyzed. In this study, atracurium (0.4-0.5 mg/kg), vecuronium (0.1-0.2 mg/kg) or rocuronium (0.6-1 mg/kg) were used for a modified rapid sequence induction. Generally, I use a rapid sequence induction with pentothal (4-6mg/kg)and succinylcholine (2 mg/kg).
While classically a Ramstedt procedure is used to open the pylorus, recently laparoscopic pyloromyotomy has been shown to be an acceptable alternative.It has been found to be associated with a faster time to full feeds. An alternative open approach uses a supraumbilical incision. Both of the latter procedures may increase the duration of surgery, but typically the procedure lasts less than 90 minutes, and requires an intermediate acting muscle relaxant in conjunction with an inhalation agent. Usually no narcotics are required. Surgeons can infiltrate the wound with local anesthesia prior to closure.
Respiratory depression has been reported in the immediate postoperative period and up to 7 hours after anesthesia in full term infants. This may be related to a delayed correction of CNS alkalosis. Narcotics are not usually needed for analgesia. Oral feeds are usually initiated 6-8 hours after surgery. The typical time in hospital to return to full feeds is usually 2-3 days; HMO’s are pushing for a faster discharge.
Toddler--Foreign
Body Aspiration
Disease
State
Anesthetic
Considerations
Preoperative
Assessment
Intraoperative
Management
Postoperative
Care
Foreign body aspiration is the cause of death of more than 300 children yearly in the United States. While this can occur in any age group, the majority of children are between the ages of 1-3 years. In a recent large report, peanuts were by far the most commonly aspirated foreign body. This was followed by organic material, other nuts, popcorn, seeds, plastic objects and pins. Coughing, choking, and/or wheezing are present in the history and physical findings of over 90% of the children. A CXR may be helpful, particularly if inspiration/expiration films are done. Air trapping is the most common radiographic finding. Only a small proportion of inhaled objects will be opaque on the films. Fluoroscopy is less commonly performed. Most foreign bodies end up in a mainstem bronchus with a slight preponderance of the right side.
A child in distress with cyanosis and wheezing will need urgent removal of the foreign body in the operating room. If the situation is not acute, and particularly if the child has recently eaten, consideration should be given to delay until some gastric emptying has occurred. The anesthesiologist should listen to the breath sounds for a baseline, as this may give an indication of where the foreign body is lodged. One should also view the preoperative CXR to determine the extent of known pathophysiology (air trapping, infiltrates, etc.) prior to induction. The decision whether to premedicate or to allow parental presence for the induction is dictated by the individual situation. In some situations it may be advantageous to allow the parent to be present.
The decision to perform an inhalation induction versus an intravenous induction must be made according to the NPO and the airway status. Ideally, in order to maintain the airway and not dislodge the foreign body, an inhalation induction with sevoflurane or halothane and oxygen is performed. Once the child is deeply anesthetized, 2% lidocaine is used to topicalize the vocal cords and proximal trachea. The surgeons will usually use a rigid bronchoscope with a ventilating sideport to remove the foreign body. Airways that are particularly irritable may require additional boluses of propofol during the procedure, as ventilation is compromised, and rapidly changing the depth of anesthesia with an inhalation agent may not be possible. Be prepared to relax the vocal cords with either succinylcholine or propofol at the time the object is removed, to allow ease of passage. If it drops into the trachea, anticipate the worst…..Once the foreign body is removed, the child can be allowed to awaken with a mask, or an endotracheal tube can be inserted and subsequently removed when the child is fully awake. The latter is important for the child who had a full stomach, or one who was difficult to control because of all the wheezing, coughing and irritability.
Many of these children will have more wheezing and stridor following their surgery than prior to surgery. Rigid bronchoscopes, particularly if multiple insertions were performed, may cause subglottic edema. It is our routine policy to administer decadron 0.6-1 mg/kg intravenously during the procedure to minimize postoperative croup. Racemic epinephrine may be required in the PACU. Additionally, if the foreign body was fragmented or if infection and inflammation were noted distal to the obstruction, wheezing is common in the postoperative period. Nebulized albuterol and chest PT will improve the symptoms. Antibiotics are indicated if infection is suspected.
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