Separation surgery for conjoined twins is extremely long and entails massive blood loss and fluid shifts; therefore, it should not be performed during the neonatal period . To facilitate safer management, it is usually planned for between the postnatal age of 4 and 11 months . In the present case, the general health of both twins was stable and it was decided that the surgery would be performed at 5 months after birth.
Conjoined twins are classified according to the site of conjunction: chest (thoracopagus), abdomen (omphalopagus), sacrum (pygopagus), pelvis (ischiopagus), and head (craniopagus). Thoracopagus conjunction is the most common type and is associated with a significant risk for respiratory and cardiovascular complications. Some omphalopagus twins have fused livers in which case blood loss may be considerable during separation surgery. Airway management can be challenging due to positioning issues in thoracopagus and omphalopagus .
The current case was pygopagus, which accounts for approximately 6–19% of all conjoined twins [4, 5]. Because of the rotation of the spine, the upper bodies of both twins were in a supine position and they could be positioned side by side. They had no facial abnormalities and difficult mask ventilation was not anticipated. The effects of cross-circulation should be assessed, especially in thoracopagus and omphalopagus twins. In the current pygopagus case, preoperative imaging studies revealed limited shared circulation. Based on these respiratory and circulatory evaluations, intravenous induction was planned.
The anesthetic management of conjoined twins is challenging and requires cooperation between a large number of medical staff. A preoperative examination is essential, including the site of attachment, shared organ systems, any complications that are present, and airway assessment. Multidisciplinary team preparation is key to the successful management of separation surgery [4, 6]. It is also recommended that simulations be performed in the operating room [2, 7]. The team conducted surgical planning and simulations twice and consequently established good communication.
Two anesthesia machines, two anesthesia medication carts, and two patient monitors were used in one large operating theater. To avoid any confusion, color-coding is recommended [4, 8]. All infusion lines, equipment, respiratory systems, and drugs were color-coded for each twin (i.e., purple for twin A and orange for twin B; see Figs. 2b and Fig. 3 b).
The main intraoperative complication was the positional change of the babies. Prone position was required during the surgery for anatomical reasons. In the present case, the relationship between the left and right babies was reversed by a position change from supine to prone, causing the monitors and respiratory circuits to cross over. We realized the problem during the second simulation. Changes in the position of the babies also posed a risk for medication-related errors and dislocation of endotracheal tubes . A drug administration error resulting from the crossover of venous lines in the prone position has been reported in a similar case . To reduce this risk, we used the anesthesia machine and monitor on the opposite side during anesthesia induction in both twins. That is, at the time of anesthesia induction, the anesthesia machine and monitor on the right side were used for the baby on the left side and the equipment on the left side was used for the baby on the right side (Fig. 2b). The positional relationship between the babies and the anesthesia machines and monitors normalized after they were changed to the prone position (Fig. 3b).
In conclusion, anesthesiologists should be aware of the intersection of respiratory circuits and arteriovenous lines due to the change of position from supine to prone in separation surgery for conjoined twins. We used the anesthesia machines and monitors on the opposite side of each twin during anesthesia induction. This method was effective for distinguishing the twins, avoiding drug administration errors, and preventing associated problems and confusion throughout the operation.