Pediatric Anesthesia

Anesthetic Neurotoxicity in Children

This article discusses the issues raised by many studies of potential neurotoxicity of anesthetics in infants, toddlers and children.

It attempts to address varying results of different studies, and to synthesize animal evidence with pediatric studies, different times of exposure and number of anesthetics.

The authors note that test batteries may not have sufficient ability to detect subtle changes in IQ, behavioural issues and academic performance, and argue for a redirecting of testing to identify potentially subtle effects that could be related to anesthesia.

There are still no studies that show overwhelmingly that anesthesia causes harm in pediatric anesthesia and at this time no practice change is felt to be warranted for performing necessary surgeries in children

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Oxygen Saturation Index Vs. Oxygenation Index in Neonates

Beyond the PaO2/FiO2 ratio in hypoxic respiratory failure, the Oxygenation Index (OI) is used in neonates, with 15/25/40 representing mild, moderate and severe illness. This retrospective study compared invasive with non-invasive measures of severity of respiratory failure.

OI = MAP × Fio2 × 100 / Pao2, where MAP indicates mean airway pressure.

Oxygen Saturation Index (OSI), a non-invasive counterpart is defined as OSI = MAP × Fio2 × 100 / Spo2

OI and OSI showed a strong correlation. Derived OI from OSI was in good agreement and strongly predictive of clinically relevant OI cutoffs from 5 to 25.

More studies in different disease severity are needed but OSI may provide a useful non-invasive alternative to OI in this setting.

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Perioperative Opioids in Children Guidelines

The Society for Pediatric Anesthesiology issues guidelines for perioperative opioid use. Many of the recommendations are not that different to adults in terms of assessing pain, safety/monitoring, patient controlled analgesia, outpatient analgesia, side effects, adjunctive agents/regional anesthesia…

Caution is advised with the potential seizure activity of both Meperidine (Pethidine) and Tramadol, and Codeine is advised against once again due to unpredictable metabolism.

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Children’s Pain Memory

Negative pain experiences can colour children’s response to pain in the long term.

This study showed that parent, but not child, anxiety before surgery contributed to the development of negative biases in children’s memories for pain-related fear 1 month later. “Specifically, higher levels of parent trait anxiety led to children recalling higher levels of pain-related fear than they initially reported”.

Children who initially reported higher levels of pain intensity and pain-related fear tended to recall higher levels pain intensity and pain-related fear. Children who developed negatively biased memories of pain-related fear had higher postsurgical pain after surgery (ie, 3 days after discharge).

The message is to target parental anxiety as well as manage pain early and for the first few days after surgery.

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Transfontanelle Ultrasound to Predict Fluid Responsiveness in Infants

Studies have found a relationship between fluid responsiveness and respiratory variation in the arterial blood flow peak velocity in the ascending aorta.

This was a prospective observational study of 30 infants undergoing cardiac surgery. Before and after the administration of 10ml · kg–1 crystalloid, established measures – respiratory variation of the aorta blood flow peak velocity, pulse pressure variation, and central venous pressure were obtained. The respiratory variation of the internal carotid artery blood flow peak velocity was measured using transfontanelle ultrasound.

In this study the respiratory variation of the internal carotid artery blood flow peak velocity as measured using transfontanelle ultrasound predicts an increase in stroke volume in response to an intravenous fluid bolus.

Cutoffs for respiratory variation were different than aortic velocity and further larger studies are needed in diverse populations before this potentially useful non-invasive fluid responsiveness assessment modality can be more widely recommended in infants.

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Prenatal surgery of fetal open spinal neural tube defects

A full text article describes some of the unique features of anesthesia for prenatal open and fetoscopic surgery of fetal open spinal neural tube defects.

For uterine relaxation, higher MACs of Sevoflurane were used, as well as nitroglycerin and tocolytics. Higher doses as well as greater hemodynamic disturbance occurred with open surgery. Colloids were used more, presumably to lower the risk of pulmonary edema which occurred in 10%, attributable to gestational physiologic changes, tocolytic administration and liberal fluid therapy.

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Pediatric Severe Traumatic Brain Injury Guidelines

These updated guidelines on brain trauma in infants, children and adolescents help in determining our approach to brain trauma. The article does note that while progress has been made, overall the level of evidence informing these guidelines remains low. There is a need for quality randomized trials. With that in mind, the guidelines and evidence level include:

Use of ICP monitoring suggested (III)

If brain tissue oxygenation (PbrO2) used, keep > 10 mm Hg (III)

Excluding elevated ICP from a normal initial (0–6 hr after injury) CT examination of the brain is not suggested in comatose pediatric patients (III)

Routine repeat CT scan after 24 hours is not suggested for decisions about neurosurgical intervention, unless there is either evidence of neurologic deterioration or increasing ICP (III)

ICP target < 20 mm Hg suggested (III)

CPP minimum target 40 mm Hg (40-50 suggested) (III)

Bolus Hypertonic Saline (HTS) (3%) is recommended for intracranial hypertension. Recommended 2 to 5 mL/kg over 10–20 minutes (II)

Continuous infusion HTS is suggested in patients with intracranial hypertension. Suggested 3% saline between 0.1 and 1.0 mL/kg of body weight per hour, administered on a sliding scale. The minimum dose needed to maintain ICP less than 20 mm Hg is suggested (III)

Bolus of 23.4% HTS is suggested for refractory ICP. The suggested dose is 0.5 mL/kg with a maximum of 30 mL (III)

Avoid bolus administration of midazolam and/or fentanyl during ICP crises due to risks of cerebral hypoperfusion (III)

Prophylactic seizure treatment is suggested to reduce the occurrence of early (within 7 d) seizures (III)

Hyperventilation to a PaCO2 less than 30 mm Hg in the initial 48 hours not recommended. If used for refractory intracranial hypertension, advanced neuromonitoring for evaluation of cerebral ischemia is suggested (III)

Prophylactic moderate (32–33°C) hypothermia is not recommended over normothermia (II)

Moderate (32–33°C) hypothermia is suggested for ICP control, with slow rewarding 0.5-1° per 12 – 24 h (III)

High-dose barbiturate therapy is suggested in hemodynamically stable patients with refractory intracranial hypertension despite maximal medical and surgical management (III)

Decompressive craniectomy (DC) is suggested to treat refractory neurologic deterioration, herniation, or intracranial hypertension (III)

Decompressive craniectomy is suggested to treat refractory neurologic deterioration, herniation, or refractory intracranial hypertension (III)

Use of an immune-modulating diet is not recommended (II)

Initiation of early enteral nutritional support (within 72 hr from injury) is suggested (III)

The use of corticosteroids is not suggested to improve outcome or reduce ICP (III)

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Perioperative surgical home implementation and transfusion

A case control study in adolescents with idiopathic scoliosis undergoing spinal fusion analysed the impact of implementing blood‐conservation strategies within the perioperative surgical home on transfusion rates.

The standardized clinical pathway included judicious use of crystalloid management, restrictive transfusion strategy, routine use of cell saver, and standardized administration of anti‐fibrinolytics.

The primary outcome showed a significant decrease in perioperative blood transfusions.

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Anesthesia in Infancy and Neurodevelopmental Outcome

The ongoing topic of the potential harmful effects of general anesthesia on the developing brain is subjected to an international randomized study. Infants of less than 60 weeks’ postmenstrual age who were born at more than 26 weeks’ gestation undergoing inguinal herniorrhaphy, without previous exposure to general anaesthesia or risk factors for neurological injury were randomized to receive either awake-regional anaesthetic or sevoflurane-based general anaesthetia.

The primary outcome was FSIQ in the Wechsler Preschool and Primary Scale of Intelligence.

Conclusion: Slightly less than 1 h of general anaesthesia in early infancy does not alter neurodevelopmental outcome at age 5 years compared with awake-regional anaesthesia in a predominantly male study population.

This is another reassuring finding for the concerns promoted by animal, preclinical and observational studies on the same topic.

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