Balanced Anaesthesia for paediatric Ophthalmic Procedures-Juniper Publishers
Juniper Publishers-Journal of Anesthesia
Abstract
Background: Paediatric
ophthalmic surgery on under general anaesthesia poses several challenges
and is quite stressful to the child, parents as well as to the
anaesthesiologist. Unfortunately there is a paucity of literature on the
subject of anaesthetic management of visually challenged hyperactive
children posted for Vitreoretinal surgery [1,2].
Objective: Here under, balanced anaesthesia
approach where prolonged paediatric Vitreoretinal surgical procedures
are conducted under general anaesthesia as well as the eye block is
being evaluated to provide a stress free as well as event free
anaesthesia course in children.
Methods: Forty children scheduled to undergo a
variety of minimally invasive Vitreoretinal surgery [MIVS] under
general anaesthesia were recruited under the study and equal number of
subjects were randomly distributed under control group and study group.
All the children followed a standard protocol for general anaesthesia
and the monitoring. The subjects under control group received
sub-conjunctival LA block just before extubation. Whereas the subjects
under the study group received sub-tenon's block soon after induction.
The comparative parameters that were observed during the study included,
amount of Local anaesthetic that was used to produce the block, airway
device that was selected, changes in the vitals that were monitored like
ECG, HR, PR, SPO2 and NIBP, and need for reversal agent and immediate
rescue analgesia depending on the emergence status at the end of
anaesthesia.
Observation: 20 subjects under the study group
and the control group demographically matched in all the respects. All
the children underwent Vitreoretinal surgery lasting around 90 minutes.
The observed change in the heart rate was significant in the study
group. Where the heart rate fell following the LA block. The peak fall
in the heart rate was by 20% from that of basal value. This was
reflected as any significant deviation in blood pressure or the SPO2 or the ETCO2
values. In case of control group the heart rate remained stable around
its basal rate. The other noticeable change that was with respect to the
changes in the perfusion Index. In case of control group the perfusion
index came down to around 0.40 from the initial reading of 4.3. Whereas
in case of study group, the perfusion index remained stable around 3.9
throughout the procedure. On an average 5 ml of LA agent was used to
produce sub-tenon's block and 35% of patients were managed with LMA.
None of subject under study group required additional increments of
sedation, narcotics or the muscle relaxant during the course of
anaesthesia and these subjects did not require reversal agent at the
conclusion of the surgery. There was a smooth emergence and extubation
response In the study group when compared to the control group.
Keywords: Balanced anaesthesia; Vitreoretinal surgery; Paediatric anaesthesia Review of Literature
The literature search for evidence and experience of
eye blocks in paediatric Vitreoretinal surgery under general anaesthesia
yielded very few studies to draw any convincing recommendation.
Recently Chhabra A [3]
has made an enormous attempt to collect the relevant data from the year
1996. The pooled data was further analysed on 1021 children ranging
from 1 month to 16 years. Majority of children in these studies
underwent strabismus surgery and another two studies consisting of 177
children included Vitreoretinal surgery. The LA blocks that were
selected included retro bulbar block (1), peribulbar block (5) and
sub-Tenon's block (8) as adjuvant to general anaesthesia.
Discussion
In the year 1926 Lundy suggested that a balance of
agents and the technique to be used to suppress the difference
components of anaesthesia i.e. Analgesia, amnesia, muscle relaxation.
Most importantly it was later realised that abolition or attenuation of
autonomic reflexes would result in better outcome due to attenuation of
surgical stress. Administering LA block as an adjuvant to general
anaesthesia under balanced anaesthesia protocol in children undergoing
Vitreoretinal surgery would block the afferents from the site of origin
of neuro-ophthalmic reflexes. In addition, blocking of the sympathetic
component of the autonomic nervous system results in attenuation of the
profound metabolic as well as the endocrine response to the surgical
stress. Thus, the profound attenuation of surgical response can alter
and improve the outcome. These effects have been well established in the
presence of continuous thoracic epidural or following infiltration of
local anaesthetic at the site of surgery that resulted in a minimal
increase in plasma concentration of catecholamine's, cortisol and
glucagon. It has also been established that to mimic similar stress free
response under general anaesthesia alone, one has to administer large
doses of polyphramacological agents. The findings of the present study
supports the view that administration of LA Block as an adjuvant to
general anaesthesia in children blocks the sympathetic component of the
autonomic nervous system as well as the neuro-ophthalmic reflex to
provide a stress free anaesthesia even at lighter planes. This has
reflected in a stable perfusion index and heart rate when compared to
the control group. The block at the site of origin of neuro-ophthalmic
reflexes resulted in [a]. Eye remaining in the centre position. [b]
Anaesthetic sparing effect with minimal need for muscle relaxant and the
reversal agent or the rescue post operative analgesia [c]. assures a
smooth and event free emergence from anaesthesia.
Conclusion
Sub-tenon's block after administering general
anaesthesia under balanced anaesthesia technique provides a stress free
and stable outcome in children undergoing Vitreoretinal surgery.
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