Elisabeth Dewhirst

Cardiac Arrest Following Ketamine Administration for Rapid Sequence Intubation

Given their relative hemodynamic stability, ketamine and etomidate are commonly chosen anesthetic agents for sedation during the endotracheal intubation of critically ill patients. As the use of etomidate has come into question particularly in patients with sepsis, due to its effect of adrenal suppression, there has been a shift in practice with more reliance on ketamine. However, as ketamine relies on a secondary sympathomimetic effect for its cardiovascular stability, cardiovascular and hemodynamic compromise may occur in patients who are catecholamine depleted. We present 2 critically ill patients who experienced cardiac arrest following the administration of ketamine for rapid sequence intubation (RSI). The literature regarding the use of etomidate and ketamine for RSI in critically ill patients is reviewed and options for sedation during endotracheal intubation in this population are discussed.

Chest wall rigidity in two infants after low-dose fentanyl administration.

Since its introduction into clinical practice, it has been known that fentanyl and other synthetic opioids may cause skeletal muscle rigidity. Involvement of the respiratory musculature, laryngeal structures, or the chest wall may impair ventilation, resulting in hypercarbia and hypoxemia. Although most common with the rapid administration of large doses, this rare adverse effect may occur with small doses especially in neonates and infants. We present 2 infants who developed chest wall rigidity, requiring the administration of neuromuscular blocking agents and controlled ventilation after analgesic doses of fentanyl. Previous reports regarding chest wall rigidity after the administration of low-dose fentanyl in infants and children are reviewed, the pathogenesis of the disorder is discussed, and treatment options offered.

Accuracy of Noninvasive and Continuous Hemoglobin Measurement by Pulse Co-Oximetry During Preoperative Phlebotomy

Background: In recent years, the continuous noninvasive hemoglobin measurement has been offered by devices using advanced pulse oximetry technology. Accuracy has been established in healthy adults as well as in surgical and intensive care unit patients but not in the setting of acute hemorrhage. In this study, we evaluated the accuracy of such a device in the clinical setting of preoperative phlebotomy thereby mimicking a scenario of acute blood loss. Methods: This prospective study included patients undergoing surgical repair of congenital heart disease (CHD) for whom preoperative phlebotomy was planned. Blood was removed after the induction of anesthesia and prior to the start of the surgical procedure. Replacement with crystalloid was guided by hemodynamic variables and cerebral oxygenation measured by near-infrared spectroscopy. Hemoglobin was measured by bedside whole blood analysis (total hemoglobin [tHb]) before and after phlebotomy, and concurrent measurements from the pulse co-oximeter (noninvasive, continuous, or spot-check testing of total hemoglobin [SpHb]) were recorded. Results: The study cohort included 45 patients ranging in age from 3 months to 50 years. Preoperative phlebotomy removed an average of 9.2 mL/kg of blood that was replaced with an average of 7.2 mL/kg of crystalloid. The pre- and postphlebotomy tHb values were 13.0 ± 1.9 and 12.4 ± 1.8 g/dL, respectively. The absolute difference between the tHb and SpHb (▵Hb) was 1.2 ± 0.1 g/dL. Bland-Altman analysis revealed a bias of 0.1 g/dL, a precision of 1.5 g/dL, and 95% limits of agreement of −2.8 to 3.1 g/dL. In 52.2% of the sample sets, the SpHb was within 1 g/dL of the actual hemoglobin value (tHb), and in 80% of the sample sets, the SpHb was within 2 g/dL. No variation in the accuracy of the deviation was noted based on the patient’s age, weight, or type of CHD (cyanotic versus acyanotic). Conclusion: The current study demonstrates that the accuracy of continuous, noninvasive hemoglobin measurement was not affected by acute blood loss simulated by preoperative phlebotomy. Although the device provided a clinically acceptable correlation with the actual hemoglobin value and offers the value of a continuous trend monitor, given the precision of the device, it does not appear that actual transfusion decisions can be based on the device alone.

Ultrasound-guided trunk and core blocks in infants and children

Regional anesthetic techniques for perioperative analgesia in children are being increasingly utilized with the reported advantages of providing superior analgesia, decreasing opioid consumption, and reducing opioid-related adverse effects. The following article reviews the available literature regarding core and trunk blocks in infants and children; specifically, transversus abdominis plane, ilioinguinal/iliohypogastric nerve, rectus sheath, lumbar plexus, and paravertebral and intercostal nerve blockade. The common indications and potential complications and adverse effects for each block are presented. Additionally, the anatomy and techniques needed for their performance are reviewed. Finally, a summary of the relevant literature in relation to each peripheral nerve block technique is included.

Perioperative management of the pediatric patient with traumatic brain injury

TBI and its sequelae remain a major healthcare issue throughout the world. With an improved understanding of the pathophysiology of TBI, refinements of monitoring technology, and ongoing research to determine optimal care, the prognosis of TBI continues to improve. In 2003, the Society of Critical Care Medicine published guidelines for the acute management of severe TBI in infants, children, and adolescents. As pediatric anesthesiologists are frequently involved in the perioperative management of such patients including their stabilization in the emergency department, familiarity with these guidelines is necessary to limit preventable secondary damage related to physiologic disturbances. This manuscript reviews the current evidence‐based medicine regarding the care of pediatric patients with TBI as it relates to the perioperative care of such patients. The issues reviewed include those related to initial stabilization, airway management, intra‐operative mechanical ventilation, hemodynamic support, administration of blood and blood products, positioning, and choice of anesthetic technique. The literature is reviewed regarding fluid management, glucose control, hyperosmolar therapy, therapeutic hypothermia, and corticosteroids. Whenever possible, management recommendations are provided.

Accuracy of the CNAP monitor, a noninvasive continuous blood pressure device, in providing beat-to-beat blood pressure readings in the prone position

STUDY OBJECTIVE To assess the accuracy of a noninvasive continuous arterial pressure (CNAP) monitor in patients who are positioned prone in the operating room. DESIGN Prospective study. SETTING Operating room at a childrens hospital. PATIENTS 20 pediatric patients, aged 13.8 ± 2 years, and weight 63.7 ± 18.8 kg, scheduled for surgery in the prone position, and for which arterial catheter placement was planned. INTERVENTIONS Measurements were recorded with an arterial line (AL) and a new noninvasive continuous blood pressure (BP) monitor. MEASUREMENTS Systolic (SBP), diastolic (DBP), and mean arterial (MAP) pressure readings were captured from an arterial cannula and the CNAP device every minute during anesthesia. MAIN RESULTS The study cohort consisted of analysis of 4104 pairs of SBP, DBP, and MAP values, which showed an absolute difference between the AL and CNAP device readings of 7.9 ± 6.3 mmHg for SBP, 5.3 ± 4.3 mmHg for DBP, and 4.6 ± 3.9 mmHg for MAP. Bland-Altman analysis of MAP values showed a bias of 0.26 mmHg, with upper and lower limits of agreement of 12.18 mmHg and -11.67 mmHg, respectively. CNAP readings deviated from arterial values by ≤ 5 mmHg in 67% of MAP values, 59% of DBP values, and 43% of SBP readings. The difference was ≤ 10 mmHg for 94% of MAP readings, 90% of DBP values, and 73% of SBP readings. CONCLUSIONS During prone positioning, the CNAP monitor provided clinically acceptable accuracy for MAP values, similar to those reported in adults in the supine position.

Dexmedetomidine as part of balanced anesthesia care in children with malignant hyperthermia risk and egg allergy.

Malignant hyperthermia is an acute hypermetabolic crisis triggered in susceptible patients by the administration of succinylcholine or a volatile anesthetic agent. When anesthesia care is provided to malignant hyperthermia-susceptible patients, a total intravenous anesthesia technique with propofol is frequently chosen. However, coexisting allergies to egg and soybeans may contraindicate the use of propofol. We present our experience with the use of dexmedetomidine as part of the anesthesia regimen in 3 patients with family histories of malignant hyperthermia and personal histories of egg or soybean allergies. In 2 patients, dexmedetomidine was used as part of a general anesthesia regimen and for sedation during spinal anesthesia in the third patient. Previous reports of the use of dexmedetomidine in patients susceptible to malignant hyperthermia are reviewed, and its benefits in such patients are discussed.

Propofol and remifentanil for rapid sequence intubation in a pediatric patient at risk for aspiration with elevated intracranial pressure.

Aspiration is a significant cause of anesthetic morbidity, occurring most commonly during the induction of anesthesia. For patients with a high likelihood of aspiration, rapid sequence intubation (RSI) techniques may minimize this risk by reducing the time between the loss of protective airway reflexes and the placement of a cuffed endotracheal tube. Although RSI frequently involves the administration of a neuromuscular-blocking agent (NMBA) such as succinylcholine or rocuronium, there are times when the administration of an NMBA is contraindicated or undesirable. We present an 11-year-old boy who presented with vomiting, papilledema, and a history concerning for an undiagnosed neuromuscular disorder. Deep sedation or anesthesia was required during an emergent lumbar puncture to evaluate his symptoms. Rapid sequence intubation was successfully performed with propofol and remifentanil without the use of an NMBA. We highlight the anesthetic considerations in such a clinical scenario and review the literature regarding the combination of remifentanil and propofol for RSI.