Jason Hayes

Duchenne muscular dystrophy: an old anesthesia problem revisited

Patients with Duchenne and Becker muscular dystrophy suffer from a progressive deterioration in muscle secondary to a defect in the dystrophin gene. As such, they are susceptible to perioperative respiratory, cardiac and other complications, such as rhabdomyolysis. Inhalational anesthetic agents have been implicated as a cause of acute rhabdomyolysis that can resemble malignant hyperthermia (MH). This article reviews perioperative ‘MH‐like’ reactions reported in muscular dystrophy patients and groups them into three categories according to clinical presentation. The etiology and underlying pathophysiological process responsible for these reactions is discussed and recommendations are proposed for the safe anesthetic management of these patients.

Dose-response of remifentanil for tracheal intubation in infants

To compare the dose-response of remifentanil for tracheal intubation in infants and children, 32 healthy full-term infants and 32 children were anesthetized with 10 &mgr;g/kg glycopyrrolate and 4.0 mg/kg propofol and administered 1 of 4 doses of remifentanil (1.25, 1.50, 1.75, or 2.00 &mgr;g/kg) to facilitate tracheal intubation. We determined the effective doses of remifentanil in 50% (ED50) and 98% (ED98) of patients by using logistic regression analysis. We found that logistic regression curves were similar for infants and children (P = 0.38). ED50 and ED98 values for remifentanil were 1.70 ± 0.1 &mgr;g/kg and 2.88 ± 0.5 &mgr;g/kg, respectively. In a second double-blind study, 24 infants were anesthetized with propofol and randomized to receive either 3.0 &mgr;g/kg remifentanil or 2.0 mg/kg succinylcholine to facilitate tracheal intubation. The duration of apnea, tracheal intubating conditions and hemodynamic changes were determined. We found that the duration of apnea and intubating conditions after propofol/remifentanil were similar to those after propofol/succinylcholine. Bradycardia, hypotension, and chest wall rigidity did not occur. We conclude that the dose-response of remifentanil for tracheal intubation is similar in infants and children. Propofol/remifentanil provides clinically acceptable intubating conditions, stable hemodynamics, and a duration of apnea comparable to that with propofol/succinylcholine in infants.

A pilot study of the rectus sheath block for pain control after umbilical hernia repair

Background : Umbilical hernia repair, a common day surgery procedure in children, is associated with significant postoperative discomfort. The rectus sheath block may offer improved pain management following umbilical hernia repair. In this pilot study, we compared the efficacy of the rectus sheath block with that of our current standard practice – local anesthetic infiltration into the surgical wound – for pain control after umbilical hernia repair in children.

Substrate reduction therapy in juvenile GM2 gangliosidosis

Substrate reduction therapy (SRT) is considered to be a potential therapeutic option for juvenile GM2 gangliosidosis (jGM2g). We evaluated the efficacy of SRT in jGM2g, assessing neurological, neuropsychological and brain magnetic resonance imaging (MRI) outcomes over a 24-month period of treatment. In an open-label and single-center study, five jGM2g patients (mean age 14.6+/-4.5 years) received oral miglustat at doses of 100-200mg t.i.d. adjusted to body surface area. Patients underwent general and neurological examinations, neuropsychological, electrophysiological, and brain MRI studies. All patients showed neurological deterioration over the period of the study, with particularly notable worsening of gait, speech and coordination. One patient experienced acute psychosis, and another showed worsening of pre-existing epilepsy. Some neuropsychological tests showed no evidence of deterioration in the three patients with high enough cognitive functioning for reliable assessment. Profound cognitive impairment in two children precluded neuropsychological evaluation. In four patients, evaluation of brain MRI showed no changes in white matter signal abnormalities and cerebellar atrophy noted at baseline, while one patient showed progression of cerebellar and supratentorial brain atrophy. Transmission electron microscopy analysis of peripheral mononuclear cells showed reduction of intracytoplasmatic inclusions with treatment. SRT with miglustat of patients with jGM2g failed to ameliorate progressive neurological deterioration, but apparently no worsening of some areas of cognitive function tested and brain MRI lesions was noted over 24 months of treatment. The results must be interpreted with care owing to the small sample of patients and the lack of a control-arm.

Rhabdomyolysis and anesthesia

documented either. It is usually either because the digital pulsation on the radial artery is weak or it has already been unsuccessfully attempted prior to operation and the artery cannulation must be on that specific site so an attempt on the other radial artery was not applied. This is supported by the observation that most common cardiac pathologies that brachial cannulations exist were creation of shunts and arterial switch operations. The reason for the former pathology was the restriction of cannulation site to a single extremity. In the cases of transposition of the great arteries, smaller size of children and the anticipated longer duration in the ICU let us prefer relatively large size arteries to use larger cannula. We leave femoral site for both arterial and venous lines as the last choice because of the higher incidence of mechanical as well as thrombotic and infectious complications reported with it (2,3). Several potential mechanisms have been proposed to contribute the thrombotic complications such as development of intimal flaps or arterial spasms during puncture, polycythemia, poor cardiac function, and extracellular fluid deficits, which are all possible considerations for pediatric cardiac surgery (4). Brachial artery catheterization is usually undesirable because of less collateral circulation and risk of median nerve injury. However, using smaller sized catheters and palpation of adequate pulse distally minimize the risk of occlusive complications. Over the 3.5 years presented, the only major critical event was the temporary ischemic change observed in the small finger of a child. The cannula was a relatively tight one in the artery, which was not timely inspected. It was withdrawn when recognized and the ischemia resolved spontaneously over time without any permanent sequel. This child had major hemodynamic instability, which might have contributed the vascular deterioration. There were not any local infections, hematomas or permanent ischemic changes reported. The major limitation of this report is its being a retrospective data collection. The exact duration of catheters and the incidence of minor signs pointing out vascular worsening like discoloration of skin were not documented, either. Despite all suggested drawbacks of using brachial artery catheterization and lack of prospective studies, our experience with large number of patients in clinical practice encourages us to use it increasingly more over time. Thus since the dates given above, the ratio of brachial artery to all arterial interventions is becoming even more than 7.2% which is reported in this data. In conclusion, we also suggest that brachial artery can be safely considered as an alternative cannulation site for not only neonates and infants but also for the older children undergoing pediatric cardiac surgery. However, proper catheter selection as well as close and regular inspection of the arm and palpation of the pulses are mandatory to avoid major vascular complications. Elif A. Akpek Asli Donmez Department of Anesthesiology, Faculty of Medicine, Baskent University, Ankara, Turkey (email: elifakpek@baskent-ank.edu.tr)

The role of corticosteroids in Duchenne muscular dystrophy: a review for the anesthetist

Corticosteroids are a diverse class of drugs that are used in a wide variety of clinical disorders. Anesthetists are most familiar with corticosteroids in the context of their use in conditions such as cerebral edema, asthma, acute respiratory distress syndrome, and in the prevention of postoperative nausea and vomiting. In recent years, the use of these drugs has gained prominence in the management of patients with Duchenne muscular dystrophy (DMD). Although reviews of DMD have been published in the anesthesia literature, none has discussed the effects of corticosteroids on the course of this debilitating disease (1,2). This review will focus on the role of corticosteroids and their implications for anesthetic management in DMD.

Coadministration of Propofol and Remifentanil for Lumbar Puncture in Children Dose-Response and an Evaluation of Two Dose Combinations

Background:The combination of propofol and remifentanil may be particularly suitable for short-duration procedures such as lumbar puncture. The authors undertook a two-part study to evaluate coadministration of propofol and remifentanil as an anesthetic technique for lumbar puncture in children. Methods:The first part was a sequential allocation dose-finding study to determine the minimum effective dose of remifentanil when coadministered with 2.0 or 4.0 mg/kg propofol. The second was a randomized double-blind study to compare the intraoperative and recovery characteristics of 2.0 or 4.0 mg/kg propofol coadministered with the corresponding effective dose of remifentanil. Results:Effective doses of remifentanil in 98% of children were 1.50 ± 1.00 and 0.52 ± 1.06 &mgr;g/kg when coadministered with 2.0 and 4.0 mg/kg propofol, respectively. The duration of apnea was longer (median, 110 vs. 73 s; P < 0.05) and the time to awakening was shorter (median, 10 vs. 23 min; P < 0.05) after 2.0 mg/kg propofol plus 1.5 &mgr;g/kg remifentanil compared with 4.0 mg/kg propofol plus 0.5 &mgr;g/kg remifentanil. No child experienced hypotension or postprocedure nausea or vomiting after either dose combination. Conclusions:Both dose combinations (2.0 mg/kg propofol plus 1.5 &mgr;g/kg remifentanil and 4.0 mg/kg propofol plus 0.5 &mgr;g/kg remifentanil) provide effective anesthesia for lumbar puncture in children. However, the intraoperative and recovery characteristics of the two dose combinations differ in that the duration of apnea increases whereas recovery time decreases as the dose of remifentanil is increased and that of propofol is decreased.

Accuracy of manual palpation vs ultrasound for identifying the L3-L4 intervertebral space level in children.

Insertion of needles into the spinal or epidural space is an important component of modern anesthetic practice. Needles are usually inserted at or below the L3–L4 intervertebral space to minimize the risk of spinal cord injury. Manual palpation is the most common method for identifying intervertebral spaces. However, anesthesiologists are increasingly using ultrasonography to guide the placement of regional, including neuraxial, anesthetic, and analgesic blocks. We undertook an observational study to compare the accuracy of manual palpation and ultrasound for determining the L3–L4 intervertebral space level.

Liver biopsy complicated by hemorrhage in a patient with ARC syndrome

ARC syndrome is a rare disorder consisting of arthrogryposis, renal tubular acidosis and cholestatic liver disease. We report the case of a 5‐week‐old patient who underwent a percutaneous liver biopsy complicated by hemorrhage, and was subsequently diagnosed with ARC syndrome. A review of the literature demonstrates that these patients are at increased risk of bleeding caused by platelet dysfunction. The evaluation and management of unexpected hemorrhage in pediatric patients as a result of undiagnosed congenital bleeding problems is discussed.

The safety of modern anesthesia for children with long QT syndrome.

BACKGROUND:Patients with long QT syndrome (LQTS) may experience a clinical spectrum of symptoms, ranging from asymptomatic, through presyncope, syncope, and aborted cardiac arrest, to sudden cardiac death. Arrhythmias in LQTS are often precipitated by autonomic changes. This patient population is believed to be at high risk for perioperative arrhythmia, specifically torsades de pointes (TdP), although this perception is largely based on limited literature that predates current anesthetic drugs and standards of perioperative monitoring. We present the largest multicenter review to date of anesthetic management in children with LQTS. METHODS:We conducted a multicentered retrospective chart review of perioperative management of children with clinically diagnosed LQTS, aged 18 years or younger, who received general anesthesia (GA) between January 2005 and January 2010. Data from 8 institutions were collated in an anonymized database. RESULTS:One hundred three patients with LQTS underwent a total of 158 episodes of GA. The median (interquartile range) age and weight of the patients at the time of GA was 9 (3–15) years and 30.3 (15.4–54) kg, respectively. Surgery was LQTS-related in 81 (51%) GA episodes (including pacemaker, implantable cardioverter-defibrillator, and loop recorder insertions and revisions and lead extractions) and incidental in 77 (49%). &bgr;-blocker therapy was administered to 76% of patients on the day of surgery and 47% received sedative premedication. Nineteen percent of patients received total IV anesthesia, 30% received total inhaled anesthesia, and the remaining 51% received a combination. No patient received droperidol. There were 5 perioperative episodes of TdP, all in neonates or infants, all in surgery that was LQTS-related, and none of which was overtly attributable to anesthetic regimen. Thus the incidence (95% confidence interval) of perioperative TdP in incidental versus LQTS-related surgery was 0/77 (0%; 0%–5%) vs 5/81 (6.2%; 2%–14%). CONCLUSIONS:With optimized perioperative management, modern anesthesia for incidental surgery in patients with LQTS is safer than anecdotal case report literature might suggest. Our series suggests that the risk of perioperative TdP is concentrated in neonates and infants requiring urgent interventions after failed first-line management of LQTS.