Age-related changes in blood pressure and duration of motor block in spinal anesthesia

Common Inflammatory Markers and Outcome After Pediatric Cardiac Surgery With High Thoracic Epidural Anesthesia: A Randomized Controlled Study

Background: High thoracic epidural analgesia (HTEA) plays a pivotal role in reducing stress and neuroendocrine response in cardiac surgeries. Aim: The primary objective is to assess the effect of HTEA, in pediatric cardiac surgery, on inflammatory markers (interleukin [IL]-6, IL-8, and tumor necrosis factor-α). The secondary objectives are to assess its effect on various organ systems, that is, pulmonary (PaO2, P/F ratio), renal (Creatinine clearance, somatic near infrared spectroscopy [NIRS], serum neutrophil gelatinase-associated lipocalin values), cardiac (cardiac index, serum Trop-I, and lactate levels), mechanical ventilation duration, and length of stay in hospital (LOS). Methods: The study included 188 pediatric patients, who underwent, on-pump cardiac surgery randomized into the Epidural Group (n = 92) and Non-Epidural Group (n = 96). After general anesthesia, a 23 G epidural catheter was placed at the T4-5 level with a Bupivacaine infusion while the Non-epidural Group received fentanyl infusion. Blood samples were collected at four-time points, T0(preop), T1(4 h), and on the first and second postoperative days (T2 and T3). Results: The inflammatory markers were reduced, while the outcomes variables of mechanical ventilation (MV) duration had lower values in the epidural group (19.5 h vs 47.3 h, P = .002). LOS was shorter (10.1 days vs 13.3 days, P = .016). pO2, PF ratio, and renal NIRS values were better in the Epidural Gp, while other parameters were comparable. Non-epidural Gp had more complications esp. Acute kidney injury requires RRT. Conclusion: HTEA use in pediatric, on-pump cardiac surgery offers a favorable profile in terms of reduction in the inflammatory markers and positive effect on the organ systems with lesser MV duration and the LOS.

Spinal anaesthesia in neonates and infants: what about the cerebral oxygen saturation?

Background

Spinal Anaesthesia (SA) has been firmly established as an efficient and safe technique, with minimal cardio-respiratory disturbance when administered in the neonatal period. Our objective was to assess the haemodynamic consequences of SA in infants, particularly its impact on cerebral perfusion using near-infrared spectroscopy (NIRS)-based cerebral oximetry (rSco2).

Methods

All infants up to 60 weeks' postmenstrual age, whether formerly preterm or not, and undergoing spinal anaesthesia, were enrolled. Haemodynamic data records, rSco2 and mean arterial blood pressure (MAP), were prospectively collected before SA (T0) and every five min for 30 min (T30) after the puncture. Compared with baseline measures, any changes of > 10% in rSco2 and of > 20% in MAP were considered clinically significant. Relative variations of data between T0 and T30 were analysed.

Results

Data of 103 infants were analysed. The mean relative changes in rSco2 were -2.25% (97.5% CI [-3.97; -0.5]) at T15, and 0.11% (97.5% CI [-1.67; 1.90]) at T30. No significant variation of rSco2 was recorded. The mean changes in MAP were respectively -13.94% (97.5% CI [-17.74; -10.14]) at T15 and -20.27% (97.5% CI [-24,25; -16.29]) at T30. MAP decrease was statistically and clinically significant 30 min after SA. No correlation between changes in MAP and rSco2 was found. The subgroup analysis did not reveal any effect of added intrathecal clonidine or preterm birth history on these results.

Conclusions

In neonate and infants, SA did not cause clinically significant variation in cerebral oxygen saturation. Despite a significant decrease in MAP, cerebral auto-regulation seems to remain effective in neonates and not altered by spinal anaesthesia.

Intraoperative Comparison and Evaluation of Intrathecal Bupivacaine Combined with Clonidine versus Fentanyl in Children Undergoing Hernia Repair or Genital Surgery: A Prospective, Randomized Controlled Trial

Background:

Nowadays, spinal anesthesia is commonly being used in infants and children for infraumblical surgeries. Intrathecal adjuvants such as clonidine and fentanyl are used with local anesthetics for additive effects.

Aim:

The present study aims to assess and compare the effects of adding clonidine versus fentanyl to bupivacaine intrathecally in terms of propofol consumption, hemodynamic profile, adverse events, and complications intraoperatively in pediatric patients.

Settings and Design:

A prospective randomized controlled trial was conducted between June 2016 and October 2018 in pediatric patients aged 3–8 years undergoing hernia repair or genital surgery under spinal anesthesia after approval of the Institutional Ethical Committee (Reference No: SGRR/IEC/04/16).

Materials and Methods:

Patients were randomly divided into two equal sized (n = 42) study groups, while analysis was done in (n = 40) each group. Group 1 (BC) received clonidine 1 μg/kg with 0.5% bupivacaine (heavy) and Group 2 (BF) received fentanyl 0.5 μg/kg with 0.5% bupivacaine (heavy).

Statistical Analysis:

Quantitative data were expressed in mean and standard deviation. Qualitative data were expressed in proportion and percentages. Independent t-test was applied to compare the means of quantitative data, and Chi-square test was used to compare categorical data. P < 0.05 was considered statistically significant.

Results:

Patient characteristics regarding age, weight, and surgical time were comparable in the two groups. The maintenance dose and bolus dose of propofol consumed during surgery were less in Group 1 than that in the Group 2 and were found to be statistically insignificant. The values of hemodynamic parameters such as heart rate, systolic blood pressure, and diastolic blood pressure were less in Group 1 and were statistically significant at different time intervals. Sedation scores were comparable in both groups. Intraoperative incidence of bradycardia, systolic hypotension, and diastolic hypotension were high in Group 1, whereas the incidence of desaturation was high in Group 2. Intraoperative complications such as apnea and respiratory obstruction were high in Group 2, but were statistically insignificant.

Conclusion:

We conclude that intrathecal adjuvant fentanyl maintains a better hemodynamic profile in terms of adverse events such as bradycardia, systolic hypotension, and diastolic hypotension. Intrathecal clonidine maintains a better sedation level requiring less propofol for sedation. Complications such as apnea and respiratory obstruction can be attributed more to the deep sedation caused by bolus of propofol rather than the inherent properties of intrathecal adjuvant clonidine or fentanyl.

Spinal anesthesia after intraoperative cardiac arrest during general anesthesia in an infant

Although generally safe and effective, severe perioperative complications, including cardiac arrest, may occur during general anesthesia in infants. With the emergence of evidence that specific anesthetic agents may affect future neurocognitive outcomes, there has been an increased focus on alternatives to general anesthesia, including spinal anesthesia. We present a case of cardiac arrest during general anesthesia in an infant who required urologic surgery. During the subsequent anesthetic care, spinal anesthesia was offered as an alternative to general anesthesia. The risks of severe perioperative complications during general anesthesia are reviewed, etiologic factors for such events are presented, and the use of spinal anesthesia as an alternative to general anesthesia is discussed.

The Use of Regional Anesthesia in Combination With General Anesthesia for Cardiac Surgery in Children

The use of regional anesthesia in combination with general anesthesia for children undergoing cardiac surgery is the subject of a growing number of publications and presenta tions. Benefits of regional anesthesia in patients having car diac surgery include attenuation of the neuroendocrine response to surgical stress, improved postoperative pulmo nary function, enhanced cardiovascular stability, and im proved postoperative analgesia. To the extent that regional anesthesia facilitates early tracheal extubation in cardiac surgical patients, complications and costs associated with postoperative mechanical ventilation may be reduced. These benefits must, however, be weighed against the ad verse effects that may accompany the use of regional anes thesia, including hypotension, postoperative respiratory de pression, and epidural hematoma formation. In this article, the benefits and risks of regional anesthesia in infants and children undergoing open heart surgery are reviewed. In addition, specific spinal and epidural techniques currently in use are described, including management of side effects. Copyright © 2001 by W.B. Saunders Company.

Hemodynamic changes during spinal anesthesia in premature infants with congenital heart disease undergoing inguinal hernia correction

INTRODUCTION

There are conflicting reports on the effects of spinal anesthesia (SA) on hemodynamics. Data on the hemodynamic effects of SA in infants with congenital heart disease (CHD) are limited.

METHODS

We reviewed our experience with 44 unsupplemented SA with 1 mg·kg(-1) of either hyperbaric tetracaine or bupivacaine in premature and former premature infants with noncyanotic CHD. Hemodynamics and oxyhemoglobin saturation (SpO(2)) were assessed. Neither preoperative fluid boluses nor atropine was administered to any of the infants.

RESULTS

There was no significant change in systolic, diastolic, or mean blood pressures from pre-SA induction compared with end of surgery. Heart rate showed a small but systematic decline (mean change of 10 beats per minute, P < 0.01) but was within the normative range values for age. There was a small, but clinically insignificant increase in SpO(2) across the time course. Intraoperatively, two infants developed transient apneic spells. No infant developed postoperative apnea, oxygen desaturation, or bradycardia.

CONCLUSIONS

The data suggest that SA with 1 mg·kg(-1) of either hyperbaric tetracaine or bupivacaine can be used safely as the sole anesthetic for inguinal hernia repair in infants with noncyanotic CHD even when fluid restricted and apparently causes minimal respiratory complications in these infants.

Safety in pediatric regional anesthesia

The use of regional anesthesia is increasingly common in pediatric practice. This review reports the complications and risks in pediatric regional anesthesia. Few large studies reported incidence of complications. However, the different studies have shown that regional anesthesia, when performed properly, carried a very low risk of morbidity in appropriately selected infants and children. In addition, the use of ultrasound-guided peripheral nerve blockade has shown some promise toward increasing the safety profile of these already safe techniques.

Caudal blocks

Caudal anesthesia is the single most important pediatric regional anesthetic technique. The technique is relatively easy to learn (1), has a remarkable safety record (2), and can be used for a large variety of procedures. The technique has been reviewed in the English (3) and French (4) literature, as well as in German guidelines (5) and in pediatric anesthesia textbooks (6).

Intrathecal clonidine decreases propofol sedation requirements during spinal anesthesia in infants

BACKGROUND

Propofol is a popular agent for providing procedural sedation in pediatric population during lumbar puncture and spinal anesthesia. Adjuvants like clonidine and fentanyl are administered intrathecally to prolong the duration of spinal anesthesia and to provide postoperative analgesia. We studied the propofol requirement after intrathecal administration of clonidine or fentanyl in infants undergoing lower abdominal surgeries.

METHODS

Sixty-five ASA I infants undergoing elective lower abdominal surgery under spinal anesthesia were assigned into four groups in this prospective randomized double-blinded study. Group B received bupivacaine based on body weight (<5 kg = 0.5 mg kg(-1); 5-10 kg = 0.4 mg kg(-1)). Group BC received 1 microg kg(-1) of clonidine with bupivacaine, group BF received 1 microg kg(-1) of fentanyl with bupivacaine, and patients in group BCF received 1 microg kg(-1) each of clonidine and fentanyl with bupivacaine. A bolus of 2-3 mg kg(-1) of propofol bolus was administered for lumbar puncture. Sedation was assessed using a six-point sedation score (0-5) and a five-point reactivity score (0-4) which was based on a behavioral score. After achieving a sedation and reactivity score of 3-4, the patients were placed lateral in knee chest position and lumbar puncture performed and test drug administered. Further intraoperative sedation was maintained with an infusion of 25-50 microg kg(-1) min(-1) of propofol infusion.

RESULTS

The mean +/- SD infusion requirement of propofol decreased from 35.5 +/- 4.5 in group B to 33.4 +/- 5.4 microg kg(-1) min(-1) in group BF and further decreased to 16.7 +/- 6.2 microg kg(-1) min(-1) and 14.8 +/- 4.9 microg kg(-1) min(-1) in group BC and BCF, respectively. There were no statistically significant differences between BC and BCF groups. The mean sedation and reactivity scores were higher in groups BC and BCF when compared to groups B and BF.

CONCLUSION

Our study show that the requirement of propofol sedation reduces with intrathecal adjuvants. The reduction was significant with the addition of clonidine and clonidine-fentanyl combination as opposed to bupivacaine alone or with fentanyl. There was no significant difference in propofol infusion requirement with the use of bupivacaine alone or with fentanyl.

Effects of intrathecal fentanyl on quality of spinal anesthesia in children undergoing inguinal hernia repair

BACKGROUND

The effect of intrathecal fentanyl on the characteristics of spinal anesthesia has not been investigated in children undergoing inguinal hernia repair. The purpose of this study was to assess whether the incidence and severity of pain during peritoneal sac traction is decreased by addition of fentanyl to bupivacaine in children undergoing inguinal hernia repair with spinal anesthesia.

METHODS

Children (6-14 years) were randomized into two groups. Group F (n = 25): hyperbaric bupivacaine plus 0.2 microg.kg(-1) of fentanyl. Group P (n = 25): hyperbaric bupivacaine plus 0.9% NaCl (placebo). The dose of bupivacaine was 0.4 mg.kg(-1). The primary variable was the incidence and severity of pain during peritoneal sac traction. Spinal block characteristics, duration of spinal anesthesia assessed by recovery of hip flexion and duration of analgesia were the secondary variables measured, and the side effects were noted.

RESULTS

There were significant differences in incidence of pain and pain scores during sac traction with lower incidence and scores in the fentanyl group (P = 0.009). Two groups were similar regarding the level of sensory block during sac traction and duration of spinal anesthesia. Duration of spinal analgesia was prolonged significantly in the fentanyl group (P = 0.025).

CONCLUSION

Intrathecal fentanyl at a dose of 0.2 microg.kg(-1) added to bupivacaine significantly improves the quality of intraoperative analgesia and prolongs postoperative analgesia in children undergoing inguinal hernia repair with spinal anesthesia.

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.

Sedation during spinal anaesthesia in infants

BACKGROUND

Neuraxial anaesthesia in adults decreases the dose of i.v. or inhalational anaesthetic needed to reach a desired level of sedation. Furthermore, spinal anaesthesia alone has a sedative effect. The mechanism behind this phenomenon is presumed to be decreased afferent stimulation of the reticular activating system after sympatholysis. We hypothesized that this mechanism is equally active in infants undergoing spinal anaesthesia.

METHODS

In total, 20 unpremedicated former preterm infants underwent surgery under spinal anaesthesia with hyperbaric bupivacaine 0.5% 1 mg kg(-1) with epinephrine 10 microg kg(-1). No additional sedatives or anaesthetics were administered. Sedation was evaluated using the bispectral index (BIS) score and the 95% spectral edge frequency (SEF(95)).

RESULTS

After spinal anaesthesia, mean (SD) BIS began to decrease significantly from baseline 97.0 (1.1) to 83.9 (14.4) after 15 min (P=0.006). BIS decreased further, reaching the lowest values after 30 min [62.2 (14.0); P<0.00001]. Mean (SD) SEF(95) declined from baseline 26.1 (1.8) Hz to 24.3 (3.1) after 5 min (P=0.02) and further to 9.9 (3.8) after 30 min (P<0.00001). Mean arterial pressure also decreased significantly from 66.5 (4.7) mm Hg within 10 min to 56.1 (5.6) after spinal anaesthesia (P=0.0002), while heart rate remained stable.

CONCLUSIONS

These results suggest that sedation after spinal anaesthesia in infants is at least as pronounced as in adults. The sedative effect of spinal anaesthesia should be kept in mind when additional sedatives are administered, especially in former preterm infants.

The safety and efficacy of spinal anesthesia for surgery in infants: the Vermont Infant Spinal Registry

Studies with modest numbers of patients have suggested that spinal anesthesia in infants is associated with a very infrequent incidence of complications, such as hypoxemia, bradycardia, and postoperative apnea. Although spinal anesthesia would seem to be a logical alternative to general anesthesia for many surgical procedures, it remains an underutilized technique. Since 1978, clinical data concerning all infants undergoing spinal anesthesia at the University of Vermont have been prospectively recorded. In all, 1554 patients have been studied. Anesthesia was performed by anesthesia trainees and attending anesthesiologists. The success rate for LP was 97.4%. An adequate level of spinal anesthesia was achieved in 95.4% of cases. The average time required to induce spinal anesthesia was 10 min. Oxygen hemoglobin desaturation to <90% was observed in 10 patients. Bradycardia (heart rate <100 bpm) occurred in 24 patients (1.6%). This study confirms the infrequent incidence of complications associated with spinal anesthesia in infants. Spinal anesthesia can be performed safely, efficiently, and with the expectation of a high degree of success. Spinal anesthesia should be strongly considered as an alternative to general anesthesia for lower abdominal and lower extremity surgery in infants.

Spinal anesthesia in children with isobaric local anesthetics: report on 307 patients under 13 years of age

BACKGROUND

Spinal anesthesia in expert hands is an excellent method for children for appropriate surgery. The aim of this study was to evaluate the effects of spinal anesthesia with isobaric solutions in 307 consecutive cases from May 2001 to August 2002.

METHODS

In this prospective study, 307 patients from 0 to 12 years of age were scheduled for spinal anesthesia with enantiomeric mixture of bupivacaine (S75 : 25R) 0.5% or racemic bupivacaine 0.5% or lidocaine 2% without glucose, for surgery compatible with the technique. The following were assessed: latency of analgesia, motor block, maximum length and duration of sensory blockade, cardiovascular changes, incidence of headache or transient neurological symptoms and cost.

RESULTS

The onset of sensory block occurred at 2.36 +/- 0.95 min. Duration of surgery was 1.29 +/- 0.83 h and the duration of stay in the postanesthesia care unit was 39.72 +/- 26.84 min. The highest level of analgesia ranged from T(9) to T(4) (mean T(6)). Onset of motor block was <2 min in all children and each had a modified Bromage score of 3 at the beginning of the surgery. At the end of the surgery 9% had score 3, 16%, score 2, 46%, score 1 and 29%, zero. Seventy five percent of all patients recovered from motor block 1 or zero at the end of the surgery. Patients older than 1 year were able to walk in 3.79 +/- 0.73 h. There was no case of oxygen desaturation. Hypotension and bradycardia occurred in one patient. Spinal anesthesia failed in five patients. Three children developed postdural puncture headache (PDPH), the youngest aged 2 years. PDPH in all three was mild or moderate. Transient radicular symptoms were not observed. The final cost of the spinal anesthesia was R dollars 49.00 compared with a mean cost of general anesthesia of R dollars 105.00.

CONCLUSIONS

Spinal anesthesia continues to gain acceptance as an alternative to general anesthesia in children. There has also been an increased use of spinal anesthesia for other surgical procedures including lower extremity orthopedic procedures as well as specific surgery procedures above the umbilicus and in patients past the neonatal period. Spinal anesthesia in children is a special method suitable for use only by anesthesiologists, expert in administering spinal anesthesia for adults. It was 54% less than the cost of general anesthesia.

Regional Anesthesia in Children

The future of regional anesthesia in children is to continue to use current techniques, but also to search for ways to make them easier to employ. The potential development of safe local anesthetic agents with much longer durations, will serve to facilitate improvements in the techniques and styles of practice. The advances in minimally invasive surgical techniques do not mean that regional techniques will not be necessary, but will result in an adaptation of techniques. Peripheral nerve blockade and local wound infiltration can still be used and in some instances, may be very appropriate.

Postoperative Analgesia After Spinal Blockade in Infants and Children Undergoing Cardiac Surgery

The aim of this prospective, randomized, controlled clinical trial was to define the opioid analgesic requirement after a remifentanil (REMI)-based anesthetic with spinal anesthetic blockade (SAB+REMI) or without (REMI) spinal blockade for open-heart surgery in children. We enrolled 45 patients who were candidates for tracheal extubation in the operating room after cardiac surgery. Exclusion criteria included age <3 mo and >6 yr, pulmonary hypertension, congestive heart failure, contraindication to SAB, and failure to obtain informed consent. All patients had an inhaled induction with sevoflurane and maintenance of anesthesia with REMI and isoflurane (0.3% end-tidal). In addition, patients assigned to the SAB+REMI group received SAB with tetracaine (0.5-2.0 mg/kg) and morphine (7 mug/kg). After tracheal extubation in the operating room, patients received fentanyl 0.3 mug/kg IV every 10 min by patient-controlled analgesia for pain score = 4. Pain scores and fentanyl doses were recorded every hour for 24 h or until the patient was ready for discharge from the intensive care unit. Patients in the SAB+REMI group had significantly lower pain scores (P = 0.046 for the first 8 h; P =0.05 for 24 h) and received less IV fentanyl (P = 0.003 for the first 8 h; P = 0.004 for 24 h) than those in the REMI group. There were no intergroup differences in adverse effects, including hypotension, bradycardia, highest PaCO(2), lowest pH, episodes of oxygen desaturation, pruritus, and vomiting.

[The use of regional anesthesia in orthopedics]

Regional anesthesia has its place in the perioperative pain management of orthopedic patients. A reduction in postoperative mortality and morbidity with regional anesthesia is acknowledged for subsets of patient populations. Single shot and continuous applications are techniques for providing regional analgesia. Continuous infusion of local anesthetics with catheter techniques provides for uninterrupted postoperative analgesia. The combination of regional and general anesthesia reduces the consumption of systemic anesthetics. The side effects of opioid therapy are thereby reduced. The inhibition of intraoperative stress reaction, especially with epidural anesthesia, helps to prevent or lower unwanted metabolic changes. Patient contentment with analgesic quality differs with the technique with which the regional anesthesia is applied (PDA, PCEA, IVRA, peripheral block, i.a. injection), and the medication (LA, opioid) used.

Spinal Anesthesia with Bupivacaine Decreases Cerebral Blood Flow in Former Preterm Infants

Spinal anesthesia is commonly used in former preterm infants (FPI). In these patients, hypotension induced by spinal anesthesia may impair cerebral blood flow. We measured cerebral blood flow velocity (CBFV) by transcranial Doppler ultrasound to assess the effect of hypotension induced by spinal anesthesia on cerebral hemodynamics. Twelve FPI scheduled for inguinal hernia repair were operated under spinal anesthesia using 1 mg/kg isobaric 0.5% bupivacaine. Systolic, diastolic, and mean middle cerebral artery CBFV were measured at 5 min before and 5 min and 10 min after spinal anesthesia using a transcranial pulsed Doppler ultrasonography. Arterial blood pressure and heart rate were recorded simultaneously. Cerebral arteries resistance index (RI) was calculated as RI = (peak systolic CBFV - end-diastolic CBFV)/peak systolic CBFV. Diastolic CBFV decreased significantly from 30.0 +/- 11.1 cm/s to 20.1 +/- 8.4 cm/s at 5 min and to 20.1 +/- 7.0 cm/s at 10 min. RI increased significantly from 0.7 +/- 0.1 to 0.8 +/- 0.1 at 5 min and 10 min. Systolic, diastolic, and mean arterial blood pressures decreased significantly at the same time intervals. We suggest that in FPI, spinal anesthesia induces a decrease in cerebral blood flow related to changes in arterial blood pressure. Whether these changes have deleterious consequences remains to be determined.

IMPLICATIONS

In former preterm infants having spinal anesthesia with bupivacaine, a decrease in cerebral blood flow velocity is displayed by middle cerebral artery transcranial Doppler examination.

Regional Anaesthesia in the Elderly

The number of elderly patients presenting for anaesthesia and surgery has increased exponentially in recent years. Regional anaesthesia is frequently used in elderly patients undergoing surgery. Although the type of anaesthesia (general versus regional anaesthesia) has no substantial effect on perioperative morbidity and mortality in any age group; it intuitively makes sense that elderly patients would benefit from regional anaesthesia because they remain minimally sedated throughout the procedures and awaken with excellent postoperative pain control. However, a multitude of factors influence the outcome, such as the type, duration and invasiveness of the operation, co-existing medical and mental status of the patient and the skill and expertise of the anaesthesiologist and surgeon. These factors make it difficult to decide if and when one technique is equivocally better than another. Thus, it is more important to optimise the overall management of the patient during the perioperative period and, in most cases, it is the quality of the anaesthetic administered rather than the type of anaesthetic which is most important. Sedatives used for regional anaesthesia in the elderly should be short acting, easy to administer, have a low adverse effect profile and high safety margin. Midazolam, lorazepam, ketamine, propofol and low-dose opioids have been successfully used for sedation in the elderly. Aging affects the pharmacokinetics and pharmacodynamics of local anaesthetics, composition and characteristics of tissues and organs within the body, and physiological functions of the body. Changes in the systematic absorption, distribution and clearance of local anaesthetics lead to an increased sensitivity, decreased dose requirement and a change in the onset and duration of action in the elderly. Decreases in neural population, neural conduction velocity and inter-Schwann cell distance can lead to an increased sensitivity to local anaesthetics in the elderly. The addition of an opioid and epinephrine (adrenaline) has been shown to be useful in central neuraxial blockade. Epinephrine also can prolong the duration of peripheral nerve blocks. However, caution must be exercised as epinephrine has the potential for causing ischaemic neurotoxicity in peripheral nerves. Regional anaesthesia appears to be safe and beneficial in elderly patients; however, every anaesthetic administered must be assessed on a case-by-case basis and particular consideration should be given to the health status of the patient, the operation being performed and the expertise of the anaesthesiologist.

Neuraxial blocks for anaesthesia and analgesia in children

PURPOSE OF REVIEW

The use of regional techniques in paediatric anaesthesia has increased dramatically. Our aim is to produce a comprehensive review of the recent literature on neuraxial blockade in infants and children, focusing on three topics: choice of local anaesthetic and adjunct drugs, technical aspects and complications.

RECENT FINDINGS

The current literature shows a trend towards using the single isomers (levobupivacaine or ropivacaine) rather than racemic bupivacaine. In addition, opioids as adjuncts are being challenged by clonidine and ketamine, which have more benign side effects. The spread of radiopaque dye within the epidural space (which may mimic that of local anaesthetic solutions) appears to be highly variable, although distribution is related to the volume injected. Recent techniques (e.g. ultrasound or stimulating catheters) have been developed to accurately identify the position of epidural catheters. In contrast to adults, neuraxial blockade using local anaesthetic solutions is associated with stable cardiovascular variables, even in children with congenital heart disease. Although the incidence of complications associated with paediatric neuraxial blockade is low, the potential risks must always be considered.

SUMMARY

It is likely that the use of epidural ketamine or clonidine as adjuncts to local anaesthetics will grow. Alternatives, such as midazolam, may offer advantages in particular circumstances, although rigorous evaluation of the safety of these solutions when injected along the neuraxis and the development of formulations without preservatives are needed. The use of stimulating caudal catheters or ultrasound-guided techniques appears to offer promising options for the future to more accurately position catheters.

Cerebral blood flow velocity in children anaesthetized with desflurane

BACKGROUND

Desflurane allows for rapid emergence and changes in depth of anaesthesia which makes it especially suitable for neuroanaesthesia. This study was designed to determine the effects of different desflurane concentrations on cerebral blood flow velocity (CBFV) in healthy children.

METHODS

Twenty children, aged 1-7 years undergoing urological surgery were studied. Anaesthesia was induced with sevoflurane in oxygen. After tracheal intubation, sevoflurane was discontinued and ventilation with desflurane in air/oxygen was initiated and normoventilation maintained. A caudal block was performed. The patients were randomized to receive three different desflurane concentrations (0.5, 1.0 and 1.5 MAC). Fifteen minutes were allowed to reach steady-state at which time CBFV was measured by transcranial Doppler sonography. Mean arterial pressure (MAP) and heart rate (HR) were simultaneously recorded at 1-min intervals.

RESULTS

Cerebral blood flow velocity increased from 0.5 to 1.0 MAC (P < 0.05), but not from 1.0 to 1.5 MAC. HR increased from 0.5 to 1.0 (P < 0.001) and from 1.0 to 1.5 MAC (P < 0.001), whereas the MAP decreased only from 0.5 to 1.0 MAC (P < 0.001).

CONCLUSIONS

Desflurane in concentrations of 1.0 and 1.5 MAC in children increases CBFV significantly when compared with 0.5 MAC. These changes were associated with a significant increase in HR and decrease in MAP.

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.

Single-dose caudal anaesthesia for two infants undergoing diagnostic brain magnetic resonance imaging: high risk and nonhigh risk

We present a case report of two infants given a bupivacaine caudal anaesthetic as a means of achieving sedation for a diagnostic brain magnetic resonance imaging (MRI). Patient 1 was born at 27 weeks of gestation and presented to our hospital at 39 weeks postconception with a history of bronchopulmonary dysplasia and apnoea/bradycardia spells. He was undergoing a brain MRI for the work up of persistent apnoea and craniofacial abnormalities. Patient 2 was a term infant at 42 weeks postconception undergoing a MRI for the work up of a seizure disorder. Both infants fell asleep shortly after placement of the caudal blocks and the studies were completed successfully without complications. Utilizing this technique, we avoided dealing with a potentially difficult airway (patient 1), exacerbating postoperative apnoea and the negative implications of intravenous sedation during a study where there is limited access to the patient's airway.

Haemodynamic changes during high spinal anaesthesia in children having open heart surgery

BACKGROUND

This prospective series examined the haemodynamic effects of high spinal anaesthesia in combination with light general anaesthesia in infants and children undergoing open heart surgery who were candidates for immediate or early postoperative extubation.

METHODS

After midazolam premedication and sevoflurane inhalation induction, 30 patients, aged 7 months to 13 years, who were undergoing open heart surgery, received spinal anaesthetics with 0.5% tetracaine D10 mixed with morphine. The spinal blocks were placed at the L2,3 or L3,4 interspace with cephalad spread being promoted by positioning the patient in 30 degrees of Trendelenburg for a minimum of 10 min. Maintenance of anaesthesia was with isoflurane 0.2-0.5% in 70% nitrous oxide to maintain heart rate and blood pressure within 20% of postinduction baseline values. Haemodynamic values were recorded at predetermined timed intervals and intraoperative events up to and including aortic cannulation. For analysis of the data, patients were divided into four age groups (< 1 years, 1-3 years, 4-6 years and > 7 years).

RESULTS

Haemodynamic stability was demonstrated in all four age groups. Statistically significant slowing of the heart rate did occur in the groups older than 1 year at 25 min, although clinically significant bradycardia requiring treatment never occurred. Hypotension did occur during specific surgical manipulations but recovered spontaneously. Atropine, fluid boluses and vasopressors were never used. At the conclusion of surgery, all patients met extubation criteria and could move all four extremities.

CONCLUSIONS

High spinal anaesthesia with hyperbaric tetracaine and morphine in combination with light general anaesthesia is well tolerated haemodynamically by the paediatric population studied.

Spinal anaesthesia for inguinal herniotomy in preterm infants sedated with nitrous oxide: a comparison of lumbar puncture in the lateral or sitting position

This study compares spinal anaesthesia for inguinal herniotomy in preterm infants in the lateral or sitting position. Thirty patients were randomly divided into two equal groups. One hour before spinal anaesthesia, a eutetic mixture of local anaesthetic cream was applied to the lower lumbar spine. Sedation with nitrous oxide 50% in oxygen was given to all patients before and during induction of spinal anaesthesia, and throughout surgery. Lumbar punctures were performed at the L4-5 interspace using a 2.5 cm 22 G needle. Isobaric bupivacaine 0.5% with epinephrine 1 : 200 000 at a bupivacaine dose of 1 mg.kg-1 was injected in the lateral or sitting position. Measurements included heart rate, blood pressure, oxygen saturation, maximum sensory block height and duration of motor block and analgesia. There were no statistically significant differences between the groups in any measured parameters. Median [range] maximum block height was T5[T4-T7] in the lateral group and T5[T4-T5] in the sitting group. The median [range] duration of motor blockade was 67 [50-85] min in the lateral group and 63 [50-80] min in the sitting group. Our results indicate that in preterm infants sedated with nitrous oxide, spinal anaesthesia for inguinal herniotomy performed with isobaric bupivacaine 0.5% at a dose 1.0 mg.kg-1 in the lateral or sitting position is equally effective and is associated with minimal side effects.

Anesthetic and perfusion issues in contemporary pediatric cardiac surgery

As the fields of pediatric cardiology and cardiac surgery advance in complexity and in accountability for clinical and economic outcomes, several issues traditionally associated with the operating room are becoming important to physicians, nurses, and respiratory therapists who take care of children after cardiac surgery. The article discusses the concepts of "fast track" cardiac surgery, regional anesthetic techniques, coagulopathies and bleeding after cardiopulmonary bypass, intraoperative ultrafiltration, and mechanical circulatory assist devices.

The timing of intravenous crystalloid administration and incidence of cardiovascular side effects during spinal anesthesia: the results from a randomized controlled trial

We conducted a randomized clinical trial to evaluate the efficacy of crystalloids in preventing spinal-induced hypotension (SIH) and cardiovascular side effects (CVSE) in a group of surgical patients. Participants were assigned to receive lactated Ringer's solution at 1-2 mL/min (Placebo group, n = 142); lactated Ringer's at 20 mL/kg starting 20 min before spinal block (n = 130); or lactated Ringer's at 20 mL/kg starting at the time of spinal block (n = 132). SIH was defined as a decrease of > or = 30% in baseline systolic blood pressure, and CVSE as SIH plus nausea, vomiting, or faintness requiring treatment. The incidence of SIH was similar in all treatment groups. Compared to placebo, crystalloid administration at the time of spinal block resulted in a significant reduction in the proportion of patients developing CVSE from 9.9% to 2.3%. The corresponding relative proportion was 0.23 (95% confidence interval, 0.07-0.78; P = 0.019), and one additional case of CVSE was avoided for each 13 patients receiving crystalloids at the time of spinal block instead of placebo. Administration of crystalloids at the time of spinal block seems to be effective because it provides additional intravascular fluids during the period of highest risk of CVSE after spinal anesthesia.

IMPLICATIONS

Crystalloids are frequently administered to nonobstetric patients minutes before spinal anesthesia to prevent cardiovascular side effects (CVSE). This randomized controlled trial shows that although crystalloids administered before spinal block result in no clinical benefit, they significantly reduce the risk of CVSE when administered at the time of spinal block.