Pediatric neuraxial blockade

The hemodynamic effects of newborn caudal anesthesia assessed by transthoracic echocardiography: a randomized, double-blind, controlled study

BACKGROUND

Caudal anesthesia has been increasingly used in abdominal, urinary tract, and lower extremity surgery of infants. However, little was known about the hemodynamic effects of caudal anesthesia in them, especially in neonates. The purpose of this prospective study was designed to investigate the hemodynamic alterations by transthoracic echocardiography in newborn baby after caudal anesthesia with plain Bupivacaine or with epinephrine added Bupivacaine.

METHODS

Thirty full-term newborn infants scheduled for lower abdominal or urinary tract surgery were randomly allocated into three groups (n = 10 each) as follows: (i) GA group: general anesthesia with sevoflurane; (ii) GA+CP group: GA with sevoflurane, combined with caudal anesthesia of plain Bupivacaine (1.25 ml x kg(-1) of 0.2%); (iii) GA+CA group: sevoflurane GA combined with caudal anesthesia of epinephrine-added Bupivacaine (1.25 ml x kg(-1) of 0.2% Bupivacaine plus 1/200,000 epinephrine). Cardiac output (CO), arterial blood pressure, and heart rate were measured before (T-5) and 5(T5), 10(T10), 15(T15) min after performance of caudal anesthesia.

RESULTS

In GA group, no significant hemodynamic alteration was observed in comparison with T-5, except HR, which decreased by 7% at T15; In GA+CP group, compared with T-5, HR decreased significantly at T5, T10 and T15, respectively, by 6%, 7% and 10%. And also CO decreased significantly at T15 by 8% compared with T-5; In GA+CA group, no significant hemodynamic alteration was observed expect diastolic arterial blood, which decreased significantly at T15 by 10% compared with T-5; At T15, the larger decrease of systolic arterial blood in GA+CP group and GA+CA group vs (GA) group (P < 0.05).

CONCLUSIONS

The study shows the stability of hemodynamic variables during caudal anesthesia with Bupivacaine and with epinephrine-added Bupivacaine in newborn infants.

The transesophageal Doppler and hemodynamic effects of epidural anesthesia in infants anesthetized with sevoflurane and sufentanil

BACKGROUND

It is thought that pediatric epidural anesthesia (EA) provides hemodynamic stability in children. However, when compared with information relating to adults, little is known about the hemodynamic effects of epidural EA on cardiac output (CO) in infants.

METHODS

Using transesophageal Doppler to monitor CO, we prospectively studied 14 infants <10 kg who were scheduled for abdominal surgery. During sevoflurane general anesthesia, CO transesophageal Doppler monitoring was performed before and after lumbar EA with 0.75 mL/kg of 0.25% bupivacaine and 1:200,000 adrenaline. CO, arterial blood pressure, and heart rate were measured before and 5, 15, and 20 min after performance of EA.

RESULTS

In patients anesthetized with sevoflurane and sufentanil, EA resulted in an increase in stroke volume by 29% (P < 0.0001) and a decrease in heart rate by 13% (P < 0.0001). EA also induced a significant decrease in systolic, diastolic, mean arterial blood pressure, and systemic vascular resistance by 11%, 18%, 15%, and 25%, respectively. Conversely, CO remained unchanged.

CONCLUSIONS

The increase in stroke volume observed is probably explained by optimization of afterload because of the sympathetic blockade induced by EA. These results confirm that EA provides hemodynamic stability in infants weighing <10 kg and supports the use of EA in this pediatric population.

The effects of spread of block and adrenaline on cardiac output after epidural anesthesia in young children: a randomized, double-blind, prospective study

Epidural anesthesia is considered to be without significant hemodynamic consequence in young children. However, conversely to adults, few studies have investigated cardiac output. Using transesophageal Doppler monitoring of cardiac output, we prospectively investigated hemodynamic alterations in 48 children (median age, 22.5 mo) receiving sevoflurane general anesthesia combined with caudal or thoracolumbar epidural anesthesia. They were randomly assigned to receive 0.8 mL/kg of plain local anesthetic mixture (lidocaine 1% + bupivacaine 0.25% (50/50) + 1 microg/mL of fentanyl) or 1 mL/kg of the same mixture with 5 microg/mL of adrenaline. No significant hemodynamic alteration was elicited in caudal and thoracolumbar groups receiving the plain mixture except a moderate decrease in heart rate. Conversely, a mixture with adrenaline added provoked a significant decrease in mean arterial blood pressure by 14% and 17%, in systemic vascular resistance by 24% and 40%, and an increase in cardiac output by 20% and 34% in caudal and thoracolumbar groups, respectively. The adrenaline effect was greater by the thoracolumbar than the caudal approach. In young children, epidural anesthesia induces an increase in cardiac output only when adrenaline is added to local anesthetics, probably through its systemic absorption from the epidural space.

IMPLICATIONS

Epidural anesthesia may induce significant hemodynamic changes, well documented in adults. Using noninvasive hemodynamic monitoring in children, we reported an increase in cardiac output and a decrease in arterial blood pressure only when epinephrine was added to epidurally-injected local anesthetics.

Benefit and risks of local anesthetics in infants and children

Regional anesthesia has become a routine part of the practice of anesthesiology in infants and children. Local anesthetic toxicity is extremely rare in infants and children; however, seizures, dysrhythmias, cardiovascular collapse, and transient neuropathic symptoms have been reported. Infants and children may be at increased risk from local anesthetics compared with adults. Larger volumes of local anesthetics are used for epidural anesthesia in infants and children than in adults. Metabolism and elimination of local anesthetics can be delayed in neonates, who also have decreased plasma concentrations of alpha(1)-acid glycoprotein, leading to increased concentrations of unbound bupivacaine. Most regional anesthetic procedures in infants and children are performed with the patient heavily sedated or anesthetized; because of this, and because a test dose is not a particularly sensitive marker of intravenous injection in the anesthetized patient, detection of intravascular local anesthetic injection is extremely difficult. The same local anesthetics used in adult anesthetic practice are also used in infants and children. Because of its extremely short duration of action, chloroprocaine has been used primarily for continuous epidural techniques in infants and children. The use of tetracaine has generally been limited to spinal and topical anesthesia. Lidocaine (lignocaine) has been used extensively in infants and children for topical, regional, plexus, epidural and spinal anesthesia. The association between prilocaine and methemoglobinemia has generally restricted prilocaine use in infants and children to the eutectic mixture of local anesthetics (EMLA). Because of its greater degree of motor block compared with other long-acting local anesthetics, etidocaine has generally been limited to plexus blocks in infants and children. Mepivacaine has been used for both plexus and epidural anesthesia in infants and children. Because postoperative analgesia is often the primary justification for regional anesthesia in infants and children, bupivacaine, a long-acting local anesthetic, is the most commonly reported local anesthetic for pediatric regional anesthesia. Given the lower toxic threshold of bupivacaine compared with other local anesthetics, the risk-benefit ratio of bupivacaine may be greater than that of other local anesthetics. Two new enantiomerically pure local anesthetics, ropivacaine and levobupivacaine, offer clinical profiles comparable to that of bupivacaine but without its lower toxic threshold. The extreme rarity of major toxicity from local anesthetics suggests that widespread replacement of bupivacaine with ropivacaine or levobupivacaine is probably not necessary. However, there are clinical situations, including prolonged local anesthetic infusions, use in neonates, impaired hepatic metabolic function, and anesthetic techniques requiring a large mass of local anesthetic, where replacement of bupivacaine with ropivacaine, levobupivacaine or (for continuous techniques) chloroprocaine appears prudent.

Spinal anaesthesia in a child with hypoplastic left heart syndrome

Hypoplastic left heart syndrome (HLHS), a complex congenital heart disease, is the most common lethal cardiac defect in neonates. Its treatment includes cardiac transplantation and/or surgical palliation. Associated extracardiac congenital abnormalities are exceptional. We report the case of a neonate with HLHS and anorectal atresia who required urgent surgical management to relieve intestinal obstruction. The surgery was successfully performed under spinal anaesthesia.

The hemodynamic effects of pediatric caudal anesthesia assessed by esophageal Doppler

Pediatric caudal anesthesia is an effective method with an infrequent complication rate. However, little is known about its cardiovascular consequences. Transesophageal Doppler, a noninvasive method, provides the opportunity for a reappraisal of the hemodynamic effects of this technique. After parental informed consent, we studied 10 children aged 2 mo to 5 yr who were scheduled for lower abdominal surgery. General anesthesia was induced using sevoflurane and was followed by the insertion of a transesophageal Doppler probe. Caudal anesthesia was performed using 1 mL/kg of 0.25% bupivacaine with 1/200,000 epinephrine. Hemodynamic variables were collected before and after caudal anesthesia. No complications arose during insertion of the probe. The mean time between the two sets of measurements was 15 min. Heart rate, systolic, diastolic, and mean arterial blood pressures were not modified by caudal anesthesia. Descending aortic blood flow increased significantly from 1.14 to 1.92 L/min. (P = 0.0002). Aortic ejection volume increased from 8.5 to 14.5 mL (P = 0.0002). Aortic vascular resistances decreased from 6279 to 3901 dynes. s(-1) x m(-5) (P = 0.005). Caudal anesthesia did not affect heart rate and mean arterial blood pressure but induced a significant increase in descending aortic blood flow.

IMPLICATIONS

Although pediatric caudal anesthesia does not alter heart rate nor arterial blood pressure, significant changes occur in regional blood flow distribution. Descending aortic blood flow increases significantly after caudal anesthesia, whereas lower body vascular resistances decrease.

The effect of bispectral index monitoring on anesthetic use and recovery in children anesthetized with sevoflurane in nitrous oxide

The utility of bispectral index (BIS) monitoring to guide anesthetic administration has been demonstrated in adults. This prospective, randomized observer-blinded study was designed to evaluate the effect of BIS monitoring on anesthetic use and recovery characteristics in pediatric patients. After data collection in 38 historical controls, 202 patients age 0-18 yr were randomized into one of two groups: standard practice (SP) and BIS guided (BIS). Patients age 0-3 yr undergoing inguinal hernia repair (IH) and patients age 3-18 yr undergoing tonsillectomy and/or adenoidectomy (TA) were selected. All patients were anesthetized with sevoflurane in 60% N(2)O/O(2). Hernia patients also received a caudal epidural anesthetic before surgery. In the BIS group, anesthetic delivery was adjusted in an effort to achieve a target BIS of 45-60 during maintenance and 60-70 during the last 15 min of the procedure. BIS was recorded throughout surgery in all patients, but data were unavailable to the anesthesiologist in the SP group. In the TA patients, BIS monitoring was associated with a significant reduction in end-tidal sevoflurane concentration during maintenance (2.4 +/- 0.6%, SP and 1.8 +/- 0.4% BIS, mean +/- SD) and during the last 15 min of the procedure (2.1 +/- 0.7, SP and 1.6 +/- 0.6, BIS). There was a 25%-40% decrease in measured recovery times. In the patients 0-6 mo of age undergoing IH, sevoflurane concentrations during maintenance (2.0 +/- 0.4% SP, 0.9 +/- 0.8 BIS), during the last 15 min (1.6 +/- 0.4% SP, 0.6 +/- 0.6% BIS), and at the end of the procedure (1.1 +/- 0.6% SP, 0.3 +/- 0.3% BIS) were smaller in the BIS group. Emergence and recovery measures were unaffected by BIS titration. In the children 6 mo-3 yr of age, there were no significant differences between the SP and BIS groups in anesthetic use or recovery measures.

IMPLICATIONS

Bispectral index monitoring in children results in less anesthetic use and faster recovery than standard practice.