During ligation of a patent ductus arteriosus, a newborn infant receives a total gas flow of 5 L/min through a nonheated Jackson-Rees system. Operating room temperature is maintained at 30°C. The primary cause of a rapid decrease in rectal temperature from 36.8°C to 35°C is
(A) absence of the central temperature control mechanism
During uncomplicated mask induction with halothane and 50% nitrous oxide in oxygen in a 6-month-old infant with a large ventricular septal defect and valvular pulmonic stenosis, SpO2 decreases from 85% (room air) to 60%; heart rate is 100 bpm and blood pressure is 62/40 mmHg. The most appropriate management is to
An 8-kg, 1-year-old child has a measured blood loss of 50 ml during the first two hours of a rectal pull-through operation. Preoperative hematocrit was 31%. Balanced saline solution 150 ml has been administered for replacement. Urine output has been 2 ml for the last hour, heart rate is 160 bpm, and blood pressure is 40/15 mmHg. The most appropriate fluid therapy is,
A 6-year-old child with asthma begins wheezing during anesthesia with halothane and nitrous oxide in oxygen. A loading dose of aminophylline is administered followed by continuous infusion. Premature ventricular contractions appear on the ECG. The most appropriate management is to
(A) administer fentanyl
(B) discontinue aminophylline
(C) increase exhalation time
(D) increase the inspired concentration of halothane
An 8-year-old child with chronic renal failure is scheduled for an operation to create an arteriovenous fistula. Laboratory studies include: Hemoglobin 6.5 g/dl, Blood gases (breathing air) : PaO2 97 mmHg, PaCO2 29 mmHg, pH 7.30 Sodium 129 mEq/L Potassium 5.5 mEq/L Chloride 101 mEq/L Bicarbonate 15 mEq/L. Before inducing general anesthesia, which of the following abnormalities should be corrected?
(B) Metabolic acidosis
(C) Potassium concentration
(D) Anemia, metabolic acidosis, and potassium concentration
A 27-month-old, 14-kg infant with intestinal obstruction is anesthetized with nitrous oxide at 1 L/min, oxygen at 0.4 L/min, and halothane at 0.8% using a Bain circuit. Ventilation is controlled at a rate of 30/min. The child's temperature is 39°C, and the PaCO2 is 65 mmHg. Which of the following is most likely?
A 2.2-kg, 6-hour-old neonate is to undergo gastrostomy followed by repair of a tracheoesophageal fistula. During induction with halothane, air, and oxygen, the abdomen becomes distended. Appropriate management is to
(A) intubate and assist spontaneous ventilation
(B) intubate and control ventilation
(C) insert an orogastric tube
(D) allow the patient to breathe spontaneously by mask until gastrostomy
A child undergoing general anesthesia is breathing spontaneously using the Jackson-Rees modification of the Ayres T-piece. Respiratory rate is 20/min and tidal volume is 75 ml. What is the minimum fresh gas flow required to prevent rebreathing?
An 18-month-old child with tetralogy of Fallot is anesthetized with halothane and nitrous oxide. Following intubation, oxygen saturation decreases abruptly from 85% to 45%. The most effective treatment is
A 2500-g, 12-hour-old infant is tracheally intubated and mechanically ventilated at a rate of 20/min with an FiO2 of 0.4 and peak inspiratory pressure of 25 cmH2O. At birth, amniotic fluid was meconium stained and Apgar scores were 2 and 7. The most recent arterial blood gas levels are PaO2, 50 mmHg, PaCO2, 55 mmHg, and pH 7.20. The most appropriate management is to
(A) administer sodium bicarbonate
(B) begin intravenous infusion of prostaglandin E,
A 2.8-kg newborn undergoes repair of a moderate-sized omphalocele. Intravenous fluid is administered at 14 mL/hr. Forty-five minutes after beginning surgery and before reduction of the omphalocele, arterial blood pressure decreases from 80/40 to 55/30 mmHg. SaO2 is 98% at an FiO2 of 0.5. Breath sounds are equal bilaterally. Which of the following is the most likely explanation for the decrease in blood pressure?
(A) Associated congenital cardiac defect
(B) Compression of the lungs by the abdominal contents
A 7-year-old, obese, 30-kg boy was anesthetized using an adult circle system containing a 3-liter bag and mask. Induction with nitrous oxide (2 liters), oxygen (1 liter), and enflurane 3% was characterized by three minutes of hyperventilation followed by apnea. Forty-five seconds later, the child moved and became difficult to control. The most likely cause of the movement is
(A) decreased alveolar concentration of enflurane during the period of apnea
(B) excessive uptake of enflurane by the child's fat
(C) higher fresh gas flows required with use of an adult circle system in a child
The lungs of a 7-kg infant are being ventilated with a volume-cycled ventilator at a rate of 20/min. The anesthetic circuit has a compressible volume of 5 ml/cm H2O, and the peak inspiratory pressure is 20 cmH2O. To achieve adequate ventilation, the ventilator tidal volume should be set at
The capnographic tracing is from a 2-month-old infant anesthetized using a pediatric circle system and mask at a fresh gas flow of 4 L/min. The sampling port is in the elbow connector. This tracing indicates
(A) adequate alveolar ventilation
(B) exhausted soda lime
(C) expired halothane concentrations representative of alveolar concentrations
A newborn is in respiratory distress. Examination shows a scaphoid abdomen, cyanosis while breathing oxygen by mask, and heart sounds in the right hemithorax. Which of the following is the most appropriate next step?
(A) Assisted ventilation with a bag and face mask
(B) Insertion of a chest tube on the left side
(C) Insertion of a nasogastric tube
(D) Tracheal intubation and assisted ventilation
(E) Tracheal intubation and expansion of the left lung
A 2600-g neonate is to undergo surgical repair of a small gastroschisis. The infant is preoxygenated with 100% oxygen. Arterial hemoglobin desaturation is noted during laryngoscopy after a rapid-sequence induction. Which of the following is the most likely cause?
(A) High fetal hemoglobin concentration
(B) High ratio of oxygen consumption to functional residual capacity
(C) Low functional residual capacity in milliliters per kilogram
A 20-kg, 5-year-old boy under treatment for five days for a cerebral contusion not requiring an operation is still unconscious. After three days of mechanical ventilation, humidified oxygen 40% via T-tube is started. Arterial blood gas analysis shows PaO2 120 mmHg, PaCO2 44 mmHg, pH 7.48, and base excess +6. A nasogastric tube is in place and draining to gravity. Daily fluid therapy has been 5% dextrose in 0.5 normal saline solution 500 ml and 5% dextrose in lactated Ringer's solution 500 ml. Serum electrolyte concentrations are sodium 140, potassium 3.2, and chloride 91 mEq/L. Serum osmolality is 300 mOsm/L. Urine output averages 15 ml/hour. Dexamethasone 8 mg/day has been the only drug therapy. This patient most likely requires
In an Infant, spinal anesthesia to a sensory level of T8 is achieved with tetracaine administered at the L2-3 interspace. Compared with spinal anesthesia to the same sensory level in an adult, this anesthetic is associated with a
Anesthesia is induced with halothane in a 3-year-old girl. Sixty seconds after administration of succinylcholine 1 mg/kg intravenously, heart rate decreases rapidly from 120 to 60 bpm. The most likely cause is
(A) acute hyperkalemia
(B) failure to pretreat with a nondepolarizing relaxant
A 3-day-old infant is comatose 18 hours after surgical correction of transposition of the great vessels. Tracheal suctioning produces only a tachycardic response. Anesthesia included midazolam 0.5 mg/kg, fentanyl 60 mcg/kg, and pancuronium 0.3 mg/kg. Which of the following is the most appropriate first step in evaluation of this infant?
A 4-month-old child undergoing a craniectomy for craniosynostosis is anesthetized with nitrous oxide and halothane. Suddenly the systolic blood pressure decreases from 75 to 30 mmHg, and the PetCO2 decreases from 35 to 6 mmHg. Which of the following maneuvers is LEAST likely to have a beneficial effect?
(A) Administration of a fluid bolus
(B) Administration of a vasopressor
(C) Application of positive end-expiratory pressure
(D) Discontinuation of nitrous oxide
(E) Flooding the surgical wound with saline solution
A 22-year-old woman with severe preeclampsia vaginally delivers a 3-kg infant after 12 hours of treatment with magnesium sulfate and continuous epidural infusion of bupivacaine 0.0625% and fentanyl 1 mcg/ml at 10 ml/hr. The infant is pink and hypotonic; heart rate is 110 bpm and blood pressure is 35/25 mmHg. Which of the following is the most appropriate initial management of the infant?
A 2-year-old child has cardiac arrest during an inguinal herniorrhaphy under general anesthesia administered during a Jackson-Rees system. The graph shows end-tidal PCO2 monitored from the tip of the endotracheal tube during cardiopulmonary resuscitation; minute ventilation is unchanged. Which of the following is the most likely cause of the change beginning at the arrow?
After an uncomplicated cesarean delivery, a full-term neonate has intermittent cyanosis. Diaphragmatic effort is vigorous and respiratory distress is relieved while crying. The most likely diagnosis is
A 5-year-old child is brought to the emergency department in considerable respiratory distress. He is sitting leaning forward and drooling. He was well until four hours ago, when temperature increased to 38.9°C and he complained of a sore throat. The most appropriate initial management is to
(A) administer nebulized racemic epinephrine
(B) gently examine the airway with a tongue blade
(C) obtain a lateral radiograph of the neck
(D) perform a rapid induction-intubation sequence
(E) perform inhalation induction without cricoid pressure
A 1100-g, 10-day-old infant is to undergo ligation of a patent ductus arteriosus after unsuccessful medical treatment. Within three minutes of intravenous administration of atropine 20 mcg, fentanyl 20 mcg, and pancuronium 0.1 mg, systemic blood pressure decreases from 80 to 30 mmHg, heart rate from 180 to 140 bpm, and arterial oxygen saturation from 90% to 80%. The most appropriate management is to
You are asked to evaluate a 2000-g male infant three hours after vaginal delivery because of a respiratory rate of 50/min, pulse rate of 115 bpm, and the following arterial blood gas values while breathing room air: PaO2 64 mmHg, PaCO2 43 mmHg, and pH 7.33. His mother received meperidine 75 mg two hours before delivery. Appropriate management includes
(A) administration of naloxone 50 mcg intramuscularly
(B) increasing the FiO2 to 0.4
(C) intubation and mechanical ventilation at an FiO2 of 0.5
(D) administration of oxygen 50% with 5 cm H2O continuous positive airway pressure
A 20-kg, 6-year-old boy is undergoing strabismus surgery under anesthesia with sevoflurane, nitrous oxide, and oxygen. The heart rate suddenly decreases from 85 to 40 bpm. Which of the following is the most appropriate first step in management?
A mechanically ventilated newborn infant is undergoing gastroschisis repair during halothane anesthesia. Based on the right radial artery catheter tracing shown, which of the following is the most appropriate conclusion?
(A) The abdomen has not yet been incised
(B) The anesthetic should be changed from halothane to isoflurane
Thirty-six hours after primary repair of meningomyelocele, a term newborn has frequent periods of apnea lasting 25 seconds and associated with oxygen desaturation to 80%. The most likely explanation is
An 8-kg, 5-month-old infant undergoes craniotomy for an arteriovenous malformation. During the procedure, severe hemorrhaging occurs and packed red blood cells 3 units are transfused rapidly. During infusion of the third unit, hypotension, nodal bigeminy, and prolongation of the QT interval are noted. The most appropriate management includes administration of
Which of the following time concentration curves would be expected in arterial blood following intravenous injection of indocyanine green dye in a 3-year-old child with a small ventricular septal defect?
A meconium-stained, full-term infant has an initial Apgar score of 2. The oropharynx is suctioned and the infant is placed on a heated table. Which of the following is the most appropriate next step in management of the airway?
(A) If the oropharynx is clear, observation for respiratory effort
(B) Placement of an oxygen mask and application of positive pressure to clear the airway
(C) Nasotracheal suctioning
(D) Tracheal suctioning using the endotracheal tube
A 14-year-old girl with status asthmaticus is receiving oxygen 3 L/min through nasal prongs. Heart rate is 110 bpm. Arterial blood gas values are PaO2 90 mmHg, PaCO2 32 mmHg, and pH 7.46. If ventilation appears unchanged, which of the following is the most reliable sign of impending respiratory failure?
A 3.3-kg neonate is brought to the operating room for repair of a left diaphragmatic hernia. A 3-mm endotracheal tube is placed to a depth of 9 cm. Initial arterial blood gas values from a right radial catheter while spontaneously breathing oxygen 50% are PaO2 82 mmHg, PaCO2 41 mmHg, pH 7.33, and base excess -5. After reduction of the hernia (during closure of the abdomen), vigorous attempts to expand the atelectatic lung are unsuccessful. The infant rapidly becomes very dusky, heart rate is 60 bpm, breath sounds are distant and squeaky bilaterally, and pulmonary compliance is decreased. Which of the following should be done first?
(A) Obtain a radiograph of the chest
(B) Place a chest tube on the left side
(C) Place a chest tube on the right side
(D) Withdraw the endotracheal tube 1 cm and suction
A 4-year-old child with myelomeningocele and a ventriculoperitoneal shunt is scheduled for bladder augmentation. One year ago, hypotension and bronchospasm occurred during laparotomy for placement of a feeding gastrostomy and responded to fluids and epinephrine. At that time, anesthesia was induced with thiopental, the trachea was intubated with a polyvinyl tracheal tube following administration of succinylcholine, and anesthesia was maintained with halothane and nitrous oxide. No diagnostic tests were performed after that incident. Which of the following should be avoided during the bladder augmentation?
A 2.8-kg 8-hour-old infant undergoes laparotomy for a ruptured omphalocele. Following primary closure of the abdominal wall, arterial blood gases are PaO2 40 mmHg (FiO2 0.6), PaCO2 55 mmHg, and pH 7.1. Blood pressure is 30/20 mmHg. After increasing the FiO2, the most appropriate action would be to
(A) obtain a radiograph of the chest immediately
(B) withdraw the endotracheal tube 1 cm
(C) assess the patient for coexisting congenital heart disease
(D) administer lactated Ringer's solution 15 ml/kg
A 5-year-old boy is to undergo microlaryngeal carbon dioxide laser vaporization of laryngotracheal papillomas under halothane administered through a small polyvinylchloride (PVC) endotracheal tube. The diluent gas mixture LEAST likely to support laser combustion of the PVC tube is
An otherwise healthy 16-year-old girl is undergoing posterior spinal fusion for thoracolumbar scoliosis. During the procedure, the most likely cause of a marked decrease in the amplitude of the somatosensory evoked potentials after stimulation of the posterior tibial nerve is
(A) administration of fentanyl 30 jag /kg for induction
(B) administration of isoflurane 1.3 MAC for maintenance
(C) administration of vecuronium 0.15 mg/kg
(D) a decrease in body temperature from 37 to 35°C
In an infant, spinal anesthesia to a sensory level of T8 is achieved with tetracaine administered at the L2-3 interspace. Compared with spinal anesthesia to the same sensory level in an adult, this anesthetic is associated with a
A 15-kg, 3-year-old child is anesthetized for an inguinal hernia repair with halothane and nitrous oxide. The trachea is intubated after administration of succinylcholine 30 mg. At the conclusion of the 45-minute procedure, the child is not breathing; a peripheral nerve twitch monitor indicates no response to a train-of-four stimulus. Further investigation is most likely to show
(A) abnormal response to nondepolarizing muscle relaxants
(B) a low dibucaine number
(C) a low plasma cholinesterase concentration
(D) an underlying myopathy
(E) a positive halothane-caffeine contracture test
A 35-kg child requires mechanical ventilation with pure oxygen at a tidal volume of 350 ml and a rate of 20/min during a severe asthma attack. The most likely cause of severe hypotension after initiating mechanical ventilation is
A 5-year-old child undergoes strabismus correction during spontaneous ventilation with halothane 1.5%, nitrous oxide and oxygen 50%. Intravenous atropine 0.2 mg is administered after inhalation induction. Ten minutes after incision, heart rate decreases from 110 bpm to 40 bpm. Which of the following is the most likely cause?
(A) Administration of phenylephrine eyedrops
(B) Inadvertent external pressure on the carotid sinus
(C) Paradoxical response to a small dose of atropine
A healthy 10-kg child is flushed and restless after premedication with meperidine 15 mg and scopolamine 0.2 mg intramuscularly. His skin is warm and dry; temperature is 38°C, pulse is 130 bpm, and blood pressure is 90/60 mmHg. The most likely cause is
A 1150-g, 10-day-old infant is undergoing a bowel resection for necrotizing enterocolitis. Heart rate is 200 bpm and blood pressure measured through a femoral artery catheter is 45/24 mmHg. The most appropriate next step is administration of
During laser excision of vocal cord polyps in a 5-year-old boy, dark smoke suddenly appears in the surgical field. The trachea is intubated and anesthesia is being maintained with halothane, nitrous oxide, and oxygen. The most appropriate initial step is to
A 16-year-old girl is receiving isoflurane, nitrous oxide, oxygen, and pancuronium for insertion of a Harrington rod. In order to perform a "wake-up test" the muscle relaxant was antagonized with neostigmine 2.5 mg and atropine 1 mg. The patient abruptly moved all extremities and was given thiopental 100 mg and succinylcholine 100 mg rapidly. Forty-five minutes later no twitch could be elicited with a nerve stimulator. The most likely explanation is
(A) a dibucaine number of 20
(B) incomplete antagonism of pancuronium
(C) prolongation of the action of succinylcholine by neostigmine
(D) spinal cord damage caused by the abrupt arousal
(E) synergism between succinylcholine and pancuronium
A 35-kg child requires mechanical ventilation with 100% oxygen at a tidal volume of 350 mL and a rate of 20/min during a severe asthma attack. The most likely cause of severe hypotension after initiating mechanical ventilation is
An infant becomes cyanotic and hypotensive after ventilatory pressures increase to 45 cm H2O during closure of the abdominal wall at the end of a gastroschisis repair. The most appropriate next step is to
(A) administer a muscle relaxant
(B) administer 5% dextrose in lactated Ringer's solution 10 ml/kg
The newborn infant of an 18-year-old heroin addict has an initial Apgar score of 1. After intubation of the trachea and ventilation with pure oxygen, the Apgar score is 3 at five minutes. Appropriate management at this time would include administration of each of the following EXCEPT
A 6-year-old boy undergoes craniotomy in the supine position for brain tumor during anesthesia with 1.5% isoflurane in oxygen. PetCO2 is 38 mmHg, heart rate is 78 bpm, and blood pressure is 130/80 mmHg. After opening the dura, the surgeon notes that the brain is bulging. Which of the following management options is LEAST likely to significantly decrease brain size?
An infant is delivered by forceps following labor in which variable decelerations were noted. Amniotic fluid was clear. Initial evaluation shows a cyanotic, limp infant with a heart rate of 80 bpm, poor respiratory efforts, and grimacing in response to suctioning. The most appropriate method of resuscitation for this newborn is
(A) vigorous tactile stimulation
(B) bag and mask ventilation with oxygen
(C) immediate endotracheal intubation
(D) administration of sodium bicarbonate 1 mEq/kg
(E) volume expansion with normal saline solution 10 mL/kg