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Anesthetic management of conjoined twins undergoing one-stage surgical separation: A single center experience.

Byline: He-Jiang Zhong, Hong Li, Zhi-Yong Du, He Huan, Tian-De Yang and Yue-Yong Qi

ABSTRACT

Objective: To summarize our experience in the anesthetic management of conjoined twins undergoing one-stage surgical separation.

Methodology: Medical records of conjoined twins admitted to our hospital for treatment and considered for surgical separation from 1996 to present were retrospectively reviewed. Four cases of conjoined twins underwent one-stage surgical separation under general anesthesia. Preoperative evaluation was performed to determine the extent of anatomical conjunction and associated anomalies. Anesthesia was simultaneously induced in all conjoined twins. The intubation procedure was successfully performed with the head slightly rotated to each baby's side, followed by the administration of vecuronium. Anesthetic agents were administered according to the estimated weight of each baby. One case of conjoined twins underwent surgical separation with cardiopulmonary bypass due to shared hearts.

Results: All conjoined twins were successfully separated. No significant respiratory or cardiac events occurred during surgery except for one twin, which died after separation because of complicated congenital heart disease.

Conclusions: Accurate preoperative evaluation, respiratory and circulatory management, and close cooperation of the multidisciplinary team are important aspects of anesthetic management of conjoined twins surgery.

KEY WORDS: Conjoined twins, Separation, Anesthetic management, Surgery.

INTRODUCTION

Conjoined twins represent an uncommon congenital malformation, with an estimated incidence of 1: 50,000-1: 100,000,1 and approximate 75 Percent of cases are females.2,3 Usually, conjoined twins are classified according to the most prominent site of conjunction: thorax (thoracopagus) 40 Percent , abdomen (xiphopagus and omphalopagus) 33 Percent , sacrum (pygopagus) 18 Percent , pelvis (ischiopagus) 6 Percent , and craniopagus (1-2 Percent).3,4

Conjoined twins usually present complex anatomical conjunction, multiple congenital anomalies, and different extents of cross- circulation. These pose multiple challenges in anesthetic management, particularly in per- operative evaluation, anesthesia induction, airway management, and maintenance of hemodynamic stability. In 1996, the first case of conjoined twins was admitted to our hospital, and since then, four cases have been undergone surgical separation.

The purpose of this case series was to summa- rize our experience in the anesthetic management of these conjoined twins who underwent one-stage surgical separation, and to review our anesthetic management strategies.

METHODOLOGY

Approval for analysis and publication of these data was obtained from the Institutional Review Board of the Xinqiao Hospital of Third Military Medical University (Chongqing, China). From 1996 to present, all conjoined twins admitted to our hospital and underwent surgical separation were retrospectively reviewed, and informed consent was given by parents or guardians. Careful physical examination and laboratory tests were performed in all conjoined twins. A detailed treatment plan was designed, according to the conditions of each case of twins.

Four cases of conjoined twins had undergone surgical separation. Anesthesia team, anesthesia machine, and monitoring system were duplicated. Anesthesia was simultaneously induced for each case of conjoined twins. Anesthetic agents were calculated according to the estimated weight of each baby and administered individually. The first case of twins was sedated with ketamine and gamma-hydroxybutyrate. The separation procedure was performed under local infiltration of 0.25 Percent procaine. In cases 2, 3, and 4, babies were induced with ketamine, midazolam, and fentanyl. All twins were facing each other, which hindered the intubation procedure. The heads of both babies were rotated, allowing a reasonable intubating position. When one baby was nasotracheally intubated with the Mcgill's forceps, the other one was continuously preoxygenated via a face mask with hand ventilation. As soon as the correct position of the tube was ensured, the procedure was repeated on the other twin.

All babies were intubated without difficulty after administration of vecuronium. The lungs were ventilated using pressure-controlled ventilation with 70-80 Percent oxygen. Anesthesia was maintained with ketamine, propofol, isoflurane or sevoflurane, fentanyl, and repeated doses of vecuronium, as required.

One-stage surgical separation was performed through an incision made on the skin bridge be- tween twins in each case. In case 4, cardiac separa- tion and reconstruction of twin B's heart were per- formed under cardiopulmonary bypass (CPB). At the end of the surgery, all babies were transferred to the ICU for close observation and care. Long term follow-up was performed after hospital discharge.

RESULTS

Patient characteristics: From 1996 to present, four cases of conjoined twins were admitted to our hos- pital and had undergone surgical separation. These included three cases of thoracopagus and one xi- pho-omphalopagus. All conjoined twins' character- istics are shown in Table-I. Three of the four cases were male, the birth weight ranged between 4.86 and 5.7 kg, averaging 5.315 kg.

All conjoined twins shared livers, and case 4 shared hearts. Other shared organs included sternum (cases 2, 3, and 4) and pericardium (cases 2 and 4). In case 4, inferior vena cava (IVC) and cholecyst were shared. Cardiovascular anomalies were detected in all conjoined twins, particularly

Table-I: Clinical characteristics of conjoined twins.

Case Year###Type Sex###Birth###Shared organs###Associated anomalies###Age at###Treatment

###weight (kg)###operation (days)

1###1996###XO###M###5.5###Liver###A: CTGA, VSD###28###Elective separation

###B: None

2###2000###TO###M###5.7###Sternum, pericardium, liver###A: ASD###96###Elective separation

###B: FDA

3###2006###TO###M###5.2###Sternum, liver###A: None###91###Elective separation

###B: FF0

4###2010###TO###F###4.86###Sternum, pericardium, heart,###A: Single ventricle,###24###Emergent

###inferior vena cava, liver,###aortectasis###separation

###cholecyst###B: Congenital heart defects no.

XO = Xipho-omphalopagus; TO = Thoracopagus; M = Male; F = Female;

CTGA = Corrected transposition of the great arteries; VSD = Ventricular septal defect;

PDA = Patent ductus arteriosus; PFO = Patent foramen ovale. No.Detailed cardiac defects was not available.

Table-II: Intraoperative anesthetic management.

Case###Weight before###Loss of###Blood products###Fluids###CPB time###Time of###Time of

###separation (kg)###blood (ml)###(ml)###(ml)###(mm)###surgery (mm)###anesthesia (mm)

1###A###4.895###60###WB: 80###70###-###152###270

B###65###WB: 80###90###-###157###270

2###A###9.4###140###WB:260###325###-###285###385

B###50###WB:150###310###-###270###385

3###A###9.95###50###PRBC:100

###FFP: 50###270###-###180###220

B###75###PRBC:100

###FFP: 50###305###-###185###220

4###A###4.45###-###115###235

B###300###PRBC:350

###FFP:100###874.5###105###370###500

in cases 1 and 4. Twin A of case 1 had corrected transposition of the great arteries (CTGA) and ventricular septal defect (VSD). In case 4, twin A presented with a single ventricle and complicated with aortectasis. Twin B also had congenital heart defects.

Intraoperative anesthetic management: Four cases of conjoined twins had undergone surgical separation under general anesthesia. Table-II provides a summary of anesthetic management during surgery. The weight before separation was 4.45-9.95 kg, averaging 7.184 kg.

In case 1, babies were kept on spontaneous breathing during surgery, except when abdominal closure required muscular relaxation. The hand ventilation was used after administration of succinylcholine in each baby. The intraoperative period was uneventful. These were also confirmed by the clinical observation of good chest expansion, satisfactory skin color, and stable vital signs.

In cases 2, 3, and 4, adequate oxygenation, venti- lation and operative conditions were achieved dur- ing surgery. Because babies required high respira- tory rates during separation of shared livers, it was necessary to hand-ventilate each baby during this procedure. In case 4, the separation procedure was performed under CPB due to shared hearts. Twin A presented with complex congenital heart disease, which unfortunately lead to death after separation. Twin B was extubated at the end of surgery and re- intubated nasally with a wire-reinforced tracheal tube to simplify postoperative ventilatory support. During surgery, the total estimated blood loss ranged between 50 and 300 ml, averaging 106 ml. Blood units were administered according to hemoglobin level (targeted level Greater than 10 g/dl). The amount of blood products administered varied between 80 and 450 ml. Warming blankets were placed under and on top of the babies, and all intravenous and irrigation fluids were prewarmed.

Table-III: Postoperative care and outcomes.

Case###Extubation time###Time in###Stay at###Complications###Surgery after###Outcome

###after operation (days)###ICU (days)###hospital (days)###separation

1###A###-###36###60###Aspiration pneumonia###-###Died at 36 days after

###separation

###B###-###17###45###-###-###Alive

2###A###3###5###74###-###-###Alive

###B###3###5###74###-###-###Died at 5 years after

###separation

3###A###4###5###146###Thoracic deformity###CTD###Alive, epilepsy

###B###4###5###146###Thoracic deformity###CTD###Alive

4###A###4###-###-###Died at separation

###B###-###29###32###MODF, DIC###DSC###Died at 29 days after

###separation

ICU = Intensive care unit; MODF = Multiple organ dysfunction failure;

DIC = Disseminated intravascular coagulation; CTD = Correct thoracic deformity; DSC = Delayed sternal closure.

The mean rectal temperature was maintained at 36 +- 1.6 oC. The mean surgical time was 214 minutes, and mean anesthesia time was 311 minutes. In case 4, the CPB time was 105 minutes. No significant respiratory or cardiac events occurred in these babies during surgery.

Postoperative care and outcomes: The postoperative care and outcomes are shown in Table-III. Twin A of case one developed aspiration pneumonia on postoperative day 3 and died of pneumonia at 36 days after separation. In cases 2 and 3, the postoperative period was uneventful. However, twin B of case 2 died of pneumonia at 5 years of age. Each child of case 3 had returned to our hospital for correction of thoracic deformity (CTD) 4 years after their separation. As for twin B of case 4, cardiac arrest occurred at 10 h after surgery. Open-chest car diac massage was performed in the ICU. Minutes later the baby regained a normal heartbeat.

How ever, the sternum could not be closed without pro ducing hypotension. Delayed sternal closure (DSC) was performed on postoperative day 5. Unfortu nately, this baby died of disseminated intravascular coagulation (DIC) and multiple organ dysfunction failure (MODF) at 29 days after separation. All survivors (n=4) in this study are now living healthily at home except for twin A of case 3, which presentsepilepsy.

DISCUSSION

This study summarizes the anesthetic management of conjoined twins who were admitted to our hospital for surgical separation. Detailed preoperative evaluation, careful intraoperative anesthetic management, and postoperative care are crucial to ensure a successful separation and a safe perioperative course.

Accurate evaluation of shared organs and asso- ciated anomalies is crucial for anesthetic manage- ment. It is necessary to define the anatomy and vascular supply of the shared organs, especially for the vital organs, such as the heart, liver, and gas- trointestinal system. The successful separation of thoracopagus twins is heavily dependent on the de- gree of cardiac fusion.5 Gastrointestinal contrast ex- amination may help to detect the conjunction of the gastrointestinal tract. MRI angiography combined with three-dimensional imaging may provide more information about shared organs.6

Although elective separation is probably preferred, emergent separation must be performed when the condition of conjoined twins deteriorates to a life threatening degree, such as one twin being difficult to resuscitate or being stillborn, severe injury of the connecting bridge during delivery, severely compromised hemodynamics or respiration, and correctable life-threatening congenital anomaly.2,6-8 However, emergent separation has a markedly higher mortality rate (70 Percent -80 Percent) than elective separation.2 In case 4, twin A deteriorated progressively towards respiratory failure with severe metabolic acidosis, the babies requiring emergent separation. Unfortunately, they presented with complex cardiac fusion, and twin A died after separation. The other baby died of MODF 29 days after separation.

General anesthesia with tracheal intubation might be preferable in conjoined twins undergoing surgical separation.4,9,10 Caudal epidural anesthesia combined with general anesthesia was also described in omphalopagus twins.11 Surgical separation of case one was performed under local anesthesia plus general anesthesia without tracheal intubation. Spontaneous breathing with 100 Percent oxygen by face mask, careful attention to drug usage, and cautious respiratory monitoring were important factors for maintaining adequate oxygenation and ventilation during surgery.

In spite of successful separation, we believe these anesthetic procedures should only be considered for twins with a simple conjunction. Tracheal intubation with mechanical ventilation would have more advantages in airway management during surgery.

Anesthetic induction may be very challenging and fraught with potential risks in conjoined twins. Induction agents and muscle relaxants administered to one baby can cause airway obstruction, hypoventilation, or apnea in the other one, particularly in conjoined twins with marked cross circulation. On the basis of these concerns, anesthesia was simultaneously induced in our conjoined twins.

Furthermore, anesthetic induction should start only when both babies can be mask-ventilated. In duction agents should be administered in relation with the weight of each baby individually.11 How ever, the exact weight of each baby is not available in conjoined twins. The approximate weight may be estimated according to the relative size. Meanwhile, in order to reduce adverse effects of anesthetics, all intravenous agents were carefully administered inreduced incremental doses.4,10

Tracheal intubation can be difficult in conjoined twins due to abnormal anatomy positioning.12

Muscle relaxant should be administered when the airway is reliably secured in both babies.8

Some authors have described that tracheal intubation was performed in conjoined twins while holding one baby above the other.5 However, other authors insisted this procedure would cause auto- transfusion between twins and induce hemodynamic disturbances,8,9 particularly in conjoined twins with significant cross-circulation. In our study, intubation procedures were successfully performed with the head slightly rotated to each baby's side, following administration of vecuronium. During this procedure, it was necessary to require another anesthesiologist to perform mask-assisted ventilation in the other baby. Some authors have suggested an awake tracheal intubation should be recommended to prevent pulmonary aspiration and airway obstruction,10 as well as avoiding suspected difficult intubation and significant cross-circulation between twins.4

However, an awake tracheal intubation may generate several problems, including coughing and straining, which can increase the risk of laryngospasm and induce serious cardiovascular responses.4,11

It is also critical to maintain the circulating volume and hemodynamic stability during surgery. We replaced fluid and blood products on the basis of arterial pressure, CVP, peripheral perfusion and hematocrit. However, because of some extent of cross-circulation between twins, it is difficult to precisely determine blood loss from each baby. Usually, weighing the gauzes, measuring the volumes in the vacuum suction bottles and serial hematocrits, contributed to determining the blood loss. The two anesthetic teams should be in close communication regarding blood loss evaluation for each baby.

Postoperative care, including mechanical ventilation, regulation of fluid and electrolyte balance, prevention of infection, and maintenance of hemodynamic stability, should be carefully managed.2 For simple procedures, postoperative ventilation may not be necessary. For prolonged surgery, postoperative mechanical ventilation may be required.

CONCLUSION

Meticulous anesthetic management is a central factor during surgical separation. Accurate preoperative evaluation, careful monitoring, maintenance of adequate ventilation, and, most of all, close cooperation between all members of the multidisciplinary team, guarantee a successful anesthetic management.

ACKNOWLEDGEMENTS

The authors are grateful to all the other anesthesiologists and specialists, who were involved in the management of these conjoined twins, and provided invaluable help.

REFERENCES

1. Mutchinick OM, Luna-Munoz L, Amar E, Bakker MK, Clementi M, Cocchi G, et al. Conjoined twins: A worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research. Am J Med Genet C Semin Med Genet. 2011;157(4):274-287.

2. Spitz L, Kiely EM. Conjoined twins. JAMA.2003;289(10):1307-1310.

3. O'Neill JA, Jr., Holcomb GW, 3rd, Schnaufer L, Templeton JM, Jr., Bishop HC, Ross AJ, 3rd, et al. Surgical experience with thirteen conjoined twins. Ann Surg. 1988;208(3):299-312.

4. Leelanukrom R, Somboonviboon W, Bunburaphong P,Kiatkungwanklai P. Anaesthetic experiences in three sets of conjoined twins in King Chulalongkorn Memorial Hospital.Paediatr Anaesth. 2004;14(2):176-183.

5. Szmuk P, Rabb MF, Curry B, Smith KJ, Lantin-Hermoso MR, Ezri T. Anaesthetic management of thoracopagus twins with complex cyanotic heart disease for cardiac assessment: special considerations related to ventilation and cross circulation. Br J Anaesth. 2006;96(3):341-345.

6. Spitz L, Kiely EM. Experience in the management of conjoined twins. Br J Surg. 2002;89(9):1188-1192.

7. Shi CR, Cai W, Jin HM, Chen F, Zhou Y, Zhou DX. Surgical management to conjoined twins in Shanghai area. Pediatr Surg Int. 2006;22(10):791-795.

8. Thomas JM. Anaesthesia for conjoined twins. Childs Nerv Syst. 2004;20(8-9):538-546.

9. Thomas JM, Lopez JT. Conjoined twins--the anaesthetic management of 15 sets from 1991-2002. Paediatr Anaesth. 2004;14(2):117-129.

10. Diaz JH, Furman EB. Perioperative management of conjoined twins. Anesthesiology. 1987;67(6):965-973.

11. Greenberg M, Frankville DD, Hilfiker M. Separation of omphalopagus conjoined twins using combined caudal epidural-general anesthesia. Can J Anaesth. 2001;48(5):478-482.

12. Shank E, Manohar N, Schmidt U. Anesthetic management for thoracopagus twins with complex cyanotic heart disease in the magnetic resonance imaging suite. Anesth Analg. 2005;100(2):361-364.

Authors Contributions:

He-Jiang Zhong, Hong Li, Zhi-Yong Du, He Huan, and Tian-De Yang provided perioperative care to the patients. He-Jiang Zhong was involved in acquisition of data and wrote the original draft of the manuscript. Yue-Yong Qi was involved in acquisition of data. Tian-De Yang was involved in the critical revision of the intellectual content of the manuscript.

How to cite this: Zhong HJ, Li H, Du ZY, Huan H, Yang TD, Qi YY. Anesthetic management of conjoined twins undergoing one-stage surgical separation: A single center experience. Pak J Med Sci 2013;29(2):509-513.doi: http://dx.doi.org/10.12669/pjms.292.3275

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Department of Radiology,

Department of Anesthesiology,

Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.

Correspondence: Tian-De Yang,

Department of Anesthesiology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. E-mail: 31011@sina.com
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Publication:Pakistan Journal of Medical Sciences
Date:Jun 30, 2013
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