Anaesthesia concerns for magnetic resonance imaging (MRI) of conjoint twins.

Sir,

Conjoint twins are identical twins in utero. The most common type is the thoracopagus joined at the thorax, followed by xiphopagus, omphalopagus, pyopagus, ischiopagus, and craniopagus.[1] We describe the procedural sedation for two pyopagus twin sister infants, aged 6 weeks, weighing 5.2 kg (approximately 2.5–2.8 kg each) posted for magnetic resonance imaging (MRI) of the spine [Figure 1]. They were delivered by lower segment caesarean section at 8 months of gestation. For the MRI, they were fed 6 h prior to the procedure and premedicated with syrup phenergan (1 mg/kg) at night and 500 mg/5 mL oral pedicloryl (triclofos) for each nearly 45 min before the scheduled scan. Two anaesthesiologists were present in the MRI room; anaesthesiologists A and B were assigned to twins A and B. At all times, communication was a closed loop. As sedation was inadequate, 1 μg (0.4 μg/kg) dexmedetomidine intranasally 45 min was administered before the procedure to both infants. As we were limited by the availability of one MRI-compatible monitor and workstation, we used a Y connector to administer oxygen through a nasal cannula to both. Two paediatric venturi-masks, MRI-compatible plastic laryngoscopes, endotracheal tubes, i-gel, and Proseal laryngeal mask airways were kept available. To avoid being awakened from sleep by the MRI-room’s excessive noise, both babies’ ears were plugged with cotton. Two extension-tubing with three-way connectors were connected to burette sets (labeled A and B) providing Isolyte P @12 mL/h each. Due to resource constraints, we decided to use electrocardiography and pulse oximeter on twin A, non-invasive blood pressure, and end-tidal carbon-dioxide on twin B, switching peripheral saturation monitor every 5 min between the twins in between MRI sequences. We checked for cross circulation by giving twin A, 0.2 mg glycopyrrolate and monitoring both babies’ heart rates. After ruling out cross-circulation, we gave 0.2 mg (0.01 mg/kg) intravenous midazolam as considered necessary. Anaesthesia personnel A and B were vigilantly monitoring chest movements, pulse volume, and monitors. One aliquot of intravenous midazolam was required for twin A but not for twin B. The whole MRI procedure took an hour with stable haemodynamics and saturation. Twin A recovered from sedation in 110 min and twin B in 120 min.

Figure 1

(a) Conjoint twin sisters lying comfortably during pre-anaesthetic evaluation, (b) The pyopagus twins are joined at the sacrum

Conjoint twins occur in 1:49,000–1:2,000,000 and pyopagus occurs in 17%.[1] Co-twins pose anaesthetic challenges due to their low birth weight, immaturity of organs, poor positioning, and possible cross-circulation. Insufficient sedation causes procedure and diagnosis delays, increasing procedure costs and inconvenience to children and their parents. For non-painful procedures such as MRI, intranasal dexmedetomidine has been found to be a safe and effective option for children.[234] Two anaesthetic professionals, anaesthesia-workstations, MRI compatible monitors, airway gadgets, and suitable size endotracheal tubes and medication carts are required for an ideal situation of doing MRI of twins [Table 1]. Cross circulation between twins should be avoided to avoid unpredictable drug effects.[5]

Table 1

Ideal conditions for MRI of conjoint twins and anaesthetic implications

Equipment, drugs, procedure	Ideal requirement/Concerns	Implications
Preprocedural evaluation	Site of attachment of twins, Shared organ systems Associated congenital malformations Airway assessment Cross-circulation assessment. Premedication and NPO status	Multidisciplinary team preparation
Anaesthesia workstation and Monitors (Electrocardiography, Peripheral oxygen saturation, End-tidal carbon dioxide, and Non-invasive blood pressure)	Two experienced anaesthesiologists Two technical officers MRI compatible Two anaesthetic workstations Two sets of ASA standard monitors Two oxygen ports Two oxygen tubing and oxygen devices Two paediatric breathing circuits Two sets of appropriate size laryngoscopes/endotracheal tubes/supraglottic airway devices Two suction machines and catheters	Colour coding of lines Closed loop communication Alternative sedation plan in case of failure
Medications	Two anaesthesia medication carts including loaded syringes with emergency, sedative drugs and induction agents (if the need arises) Two drug charts (with appropriate weights) Two extension-tubings with three-way connectors Two burette sets MRI compatible infusion pumps	Total weight/two can be used for drug calculations
MRI procedure	Manipulation of position for MRI Dislocation of airway device Complications of sedation	Closed loop communication Access for emergent intubation
Emergency intubation	The twin requiring emergency intubation can be rotated slightly laterally to allow alignment of the airway axis and enabling easy mask ventilation.	Anaesthetic agents are administered individually. Watch for respiration in the other twin
Postprocedural	Monitoring	Residual sedation

ASA- American Society of Anesthesiologists, MRI- magnetic resonance imaging, NPO-nil per oral

Closed loop communication avoiding confusion and excluding cross-circulation, and adequate sedation remain the keys to safe MRI of conjoint twins. Ideal requirements may be difficult in most hospitals and hence vigilant monitoring of airway, breathing, and colour remain the best monitors in these cases.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.