Anaesthetic management of conjoined twins’

1. PRESENTOR: Dr.Kumar
MODERATOR : Dr.chaitanya kumar

2. Introduction
 Conjoined twins are identical twins whose bodies are
joined in utero.
 It is a rare phenomenon; it is estimated to range from 1 in
50,000 births to 1 in 2,00,000 births.
 Higher incidence in southwest asia and africa.
 They are always the same sex and race.
 Approximately 75% of conjoined twin pairs are females.

3. Introduction
 They are identical twins(monozygotic and
monochorionic) who develop with a single placenta from
a single fertilized ovum.
 They are at a ratio of female to male 3:1.
 Of these, about 40% were stillborn, and 60% live born.
 About 25% of those are called miracle babies.

5. Embryology
 Two contradicting theories exist to explain the origins of conjoined twins.
 The older and most generally accepted theory is fission, in which the
fertilized egg splits partially.
 The second theory is fusion, in which a fertilized egg completely separates,
but stem cells(which search for similar cells) find like-stem cells on the
other twin and fuse the twins together.
 However, rather than 'fission' or 'fusion', the defect leading to conjoined
twins may well be a coalescence by overlapping of closely contiguous twin
embryonic axis formative fields within a single embryonic disc.

6. Embryology
 Zimmerman classic theory results when the inner
cell mass incompletely divides between 13-16 days of
fertilization.
 Incomplete division seems to be associated with
inhibition of complete differentation of various organ
systems.
 Exact reason of complex fusion is unknown.

7. Siamese Twins
 Famed twins, Chang and Bunker, were born in
Siam (now Thailand) in the early 1800's,
although they eventually settled in the United
States.
 While they were the first conjoined twins whose
medical history was documented, they were not
the first conjoined twins.
 As they traveled the world, later they were
known as "the Siamese twins."

8. Siamese Twins
 Records reference a set of conjoined boys living
in Constantinople in 945 A.D.
 Another well-known set, Mary and Eliza
Chulkhurst, lived in England in the twelth
century.

9. Classification
 Conjoined twins are usually classified by the point at
which they are joined (the Greek word pagus,
meaning "that which is fixed.")
 There have been as many as three dozen separate
types identified in the last century.

11.  Conjoined twins are further classified by the number
of limbs present and the internal organs that are
involved in the conjunction
1. Two arms: dibrachius
2. Three arms: tribrachius
3. Four arms: tertrabrachius
4. Two legs: bipus
5. Three legs: tripus
6. Four legs: tetrapus

12.  The degree of cardiac fusion, or degree of cardiopagus,
can be considered as follows (Andrews et al., 2006):
 A: Separate hearts and pericardium
 B: Separate hearts and a common/shared pericardium
 C: Fused atria and separate ventricles
 D: Fused atria and ventricle

13. Classification
TYPES OF CONJOINED TWINS:
 Those three dozen separate types are:
1. Conjunction never involving heart or umbilicus,
2. Conjunctions always involving the Umbilicus (Midline
Conjunctions) ,
3. Rare forms of conjoined twins, having different patterns..

14.  Conjunction never involving heart or umbilicus:
 I- Craniopagus.
 - Cranial union only.
 - 2% of all conjoined twins.
 II- Pygopagus.
- Posterior union of the rump.
- 19% of all conjoined twins.

15.  Conjunctions Always involving the Umbilicus (Midline
Conjunctions)
 I- Thoracopagus
 II- Cephalopagus
 III- Parapagus
 IV- Ischopagus
 V- Omphalopagus

16. Craniopagus
 There is cranial union only;
 it has an incidence of about 2% of all conjoined twins.
 Various forms and orientations of fusion may be seen,
with both neural and major vascular connections.
 Craniopagus parasiticus: A second bodiless head
attached to the head.

17. Craniopagus
 Separation is possible; depending on how much of the
brain is shared.
 There is high risk of brain damage.
 Winston (1987) described a classification based on the
deepest structures shared
1. Type A: Share only scalp and subcutaneous structures
2. Type B: Share dura mater
3. Type C: Share dura mater and arachnoid and pia mater
4. Type D: Share brain structures as well as structures
from types A, B, and C

19. Pygopagus
 Joined at the sacrum,
 Incidence is about 19% of all conjoined twins.
 Separation is possible.
 The survival rate is high.

21. Thoracopagus
 Anterior union of the upper half of the trunk.
 This is the most common form constituting approximately
35 -40 % .
 Babies face one another and have major junction at the
level of chest, with conjoined hearts and livers as well as
upper gastrointestinal (G.I) tract.
 Separation surgery depends on cardiac anatomy.

23. Omphalopagus
 Joined at the chest or abdomen.
 Similar to thoracopagus twins, but in this case the twins do not
share a heart.
 This is the second most common representing 30-35%.
 Highest rate of separation survival .
 Usually, only the liver is involved.
 Because the liver can regenerate itself, this scenario is preferred.
 Cephalothoracopagus or Janus.

25. Parapagus
 Lateral union of the lower half, extending variable distances
upward,
 Fused side-by-side with a shared pelvis
 Dithoracic: fused abdomen pelvis, not thorax
 Diprosopic: one trunk, one head, two faces with varying
fusion
 Dicephalic: one trunk, two heads, two, three, or four arms

27. Ischiopagus
 Anterior union of the lower half of the body, about 6% of all
conjoined twins.
 Heart is not involved.
 They are joined at the pelvis.
 Separation is physically possible; however, excretion and
sexual organs' impairment might present.

29. Parasitic Twins
 Rare forms of conjoined twins, having different patterns.
 1. Parasitic twins: Asymmetrical conjoined twins, one twin
being small, less formed and dependent upon the other.
 2. Fetus in fetus: Situation in which an imperfect fetus is
contained completely within the body of its sibling.

31. Anaesthetic Management
 Conjoined twinning is one of the most fascinating human
malformations.
 Treating conjoined twins can be a challenge for the surgeon
as well as anaesthesiologist.
 There are numerous conjoined twins in today's society.
 Most cases of separation are extremely risky and life
threatening.

33. Anaesthetic Management
It is a multidisciplinary team approach involving
a. extensive medical work-up
b. multiple meetings and discussions with all the
involved specialties and supporting staff.
c. involvement of parents, psychosocial counselling
of parents.
d. rehearsal of the planned surgical procedure,
media contact prior to surgery.

34. Anaesthetic Management
 There is at best a fifty-fifty shot of survival when it comes to
separation.
 If at all possible , surgery seems like the best option for
Conjoined Twins.
 Parents should make the final and informed decision on
separation.
 The rationale for deferring surgery should include single
heart, major communicating hearts or major anomalies.

35. Anaesthetic Management
 Elective separation for simple conjunctions can be
performed in the neonatal period with minimal problems
 Surgery can be best delayed until such infants are relatively
mature (4-11months of age).
 Operative survival was 50% in those operated on in the
neonatal period, but 90% in those over 4 months of age.

36. Indications for emergency separation
 Where there is damage to a connecting bridge (e.g.,
omphalopagus). This may occur at the time of delivery.
 When the condition of one twin threatens the survival of the other
(e.g., complex congenital heart disease, cardiomyopathy, sepsis).
 Deterioration of both twins because of hemodynamic and respiratory
compromise. This occurs typically in thoracopagus twins.
 When the condition of one twin is incompatible with life (e.g.,
anencephalic, acardiac, stillborn, or complex congenital anomalies) but
the other twin has a good chance of survival.

37. Concerns
 Conjoined Twins' physiology like crossed circulation,
distribution of blood volume and organ sharing with their
anaesthetic implications.
 Massive fluid shifts and loss of blood & blood components
and their rapid replenishment.
 Meticulous planning for organized management of long
hours of anaesthetic administration in two paediatric
subjects simultaneously.

38.  Airway problems due to - paediatric age, repositioning during
surgery, relative facing of twins – nasotracheal intubation is
usually carried out.
 Difficult acquiring vascular access – with the guide of
ultrasound, can be achieved.
 Thermoregulation - Fluids and blood were pre warmed before
transfusion; even irrigation fluid was also pre-warmed; twins
were draped .

39. Anaesthetic Management
 Goals of the anaesthesia care are
1. to pay meticulous attention to detail
2. monitoring
3. vigilance, & planning for the postoperative care in the
intensive care unit(ICU),
4. a dedicated team of anaesthesiologists and intensivists
for each child with duplication of all monitoring and
equipment in one operating room.

40. Anaesthetic Management
 Crossed circulation – problems
 Pharmacokinetics and Pharmacodynamics are in-consistent
in various types of twins.
 Estimation of circulatory mixing is useful to help calculate
drug dosage and fluid replacement during surgery.
 Drugs administered to one twin may have unexpected
effects on the other, especially for i.v administration when
circulatory admixing is present.

41. Anaesthetic Management
 Usually there is more cross-circulation in the
thoracopagus and craniopagus twins than in other types,
 So one can expect altered and unpredictable drug
responses.

42. Anaesthetic Management
 Crossed circulation – estimation
 The routine evaluation of cross circulation is performed
using many methods like tc-99m microcolloidal human
serum albumin (HSA).
 Injection of indigo carmine and the examination of its
excretion in urine of the other twin.
 Testing by administering drugs such as glycopyrrolate to
one twin and detecting the effect on the other twin.

44. Anaesthetic Management
 if surgery for separation is planed, careful angiographic or
radio isotopic imaging of the cross-circulation is necessary
for estimation of the cardiac output percentage which is
exchanged, as one of the twins might be dependent on the
other's circulation for survival.
 It should also be recognized that the degree of cross-
circulation is dynamic, highly dependent on both twins'
relative systemic vascular resistance.

45. Anaesthetic Management
 Szmuk P, Rabb MF, curry B described the first use of
bispectral index monitor for detection of cross-circulation in
conjoint twins,
 Synchronous ventilation is necessary to improve quality.
 These authors decided to use the carlens (y) adaptor to
achieve synchronous ventilation.

46. Anaesthetic Management
 Drug dosages:
 Recommended i.v doses of anaesthetic agents for the
combined body weight of the twins are usually halved and
then divided into two equal doses to be administered to
each twin.
 Reduced incremental doses are titrated against response
and help minimize the dangers of compounding drug effects
in one twin.

47. Importance must be given to
assessing the following
 The Airway:
Problems with the airway in conjoined twins include
1. Access to the mouth and larynx is difficult.
2. Visualization of the vocal cords may be impossible.
Close faces leave little room to move to insert
instruments in the airway.
3. Placement of the ETT through the cords is
challenging, because it tends to get caught on
the subglottis.

48.  Mechanisms of Ventilation:
 It is important to ascertain whether or not the diaphragm is
involved in the junction, or whether its function will be
affected by surgery.
 Lung compliance is affected, areas of atelectasis develop
because of the limited space between the two infants and the
abnormal anatomy of thoracic structures, the hearts are
usually abnormal.
 As one twin develops cardiorespiratory compromise with
tachycardia, tachypnea, and coughing, the other is also
affected

49.  Cardiovascular System:
 Assessment of the heart and major vascular anatomy is
crucial, because this impacts anesthesia and vice
versa.
 Craniopagus twins may, as with thoracopagus
twins, have cardiac failure.
 Because many of these infants will have spent
considerable time in the hospital, venous access
may be a challenging

50.  Disability:
1. In craniopagus twins or any of the types where the spinal
cord may be involved in surgery.
2. a full neurologic examination is required.- if any
neuroaxial intervention or procedure is planned as part
of the anesthetic.
3. Bowel and bladder function must be documented.
4. It may not always be possible to place a urinary catheter,
and urine output may not always come from the kidneys
of that infant.

51.  Gastroesophageal Reflux:
 Gastroesophageal reflux is most common in
thoracopagus twins.
 Nursing the infants with their heads up is helpful, and
the use of antireflux medication should be considered.
 While they are waiting for separation, good
nutrition is crucial to the infants’ growth.
 The body composition differs between the two twins,
as does their resting energy expenditure and caloric
intake.

52.  Skin Cover: Tissue Expanders
 Tissue expanders are inserted to facilitate skin closure
when surgery will leave a significant area uncovered.
 Anesthetic implications of the use of tissue expanders
include preoperative assessment of the pressure effects of
the expanders on the different organ systems.
 This includes the effects on the skin and the
cardiovascular system

53. Anaesthetic Management
 Requirements:
 Two sets of anaesthesiologists,
 2 work stations,
 2 operating tables,
 2 monitors,
 2 suction apparatus,
 2 sets of airway equipment &
 2 sets of resuscitative equipment,
one for each infant, are essential, as each infant
has to be separately monitored throughout the procedure.

55. MONITORING
 Standard monitoring consists of SpO2, ECG, NIBP, capnography,
temperature and urinary output is necessary.
 Arterial BP, CVP along with respiratory variables like RR, TV, Paw, and ABG
are to be monitored ,
 Urinary bladder to be catheterized for urine output measurement ,
 naso pharyngeal temperature probe for temperature monitoring,
 neuromuscular monitoring also to be placed.

56. Premedication
 Sedative or anxiolytic premedication is generally not required.
 In older sets of twins, sedation options include midazolam, chloral
hydrate—each of these has been used successfully in some twins
over 6 months of age .
 Atropine has been used for neonatal twins, but this is only necessary
when vagal stimulation is likely to occur (e.g., with laryngoscopy or
bronchoscopy) or when the use of ketamine is planned.
 If an intravenous induction is planned, the use of a topical local
anesthetic cream before venipuncture.

57. Induction
 Techniques for induction of anesthesia are determined by the airway,
the availability of intravenous access at induction, the state of
health of each infant.
 In those twins with potentially difficult airways, spontaneous
respiration with inhalational induction with sevoflurane or the
intravenous use of ketamine is helpful.
 In infants with cyanotic congenital heart disease or in those with
complex anatomy, intravenous ketamine is a safe option.

58.  Muscle relaxation must not be used until airway access is
assured.
 Rapid sequence induction is often not possible in ventrally
conjoined twins.
 Inhalational induction may be followed by the use of topical local
anesthetic spray (2% lidocaine) to the vocal cords to facilitate
intubation.
 The type of ETT and the route used (oral or nasal) are determined by
the type of conjunction (nasal is not suitable for craniopagus twins
surgery, and this route is often very difficult in thoracopagus
twins).

60. Color coding

61. Intraoperative Management
 aim to provide ideal surgical conditions in a safe and appropriate
way for the type of conjoined twins undergoing the procedure.
 Analgesia, amnesia, and muscle relaxation should be provided,
with control of the airway, ventilation, hemodynamic stability,
and temperature regulation.
 Challenges with cardiovascular depression, difficult ventilation
in thoracopagus twins and unpredictable drug absorption and
responses with uncertain degrees of cross circulation all
necessitate regular adjustments in anesthetic agents and
muscle relaxation

62.  During anesthesia, vasodilation in one infant may
result in blood being diverted to this infant, causing a
significant drop in the blood pressure of the other
twin.
 Fluid and blood loss may be anything from half to
more than five times each infant’s estimated blood
volume.
 Blood loss may be massive in craniopagus or
cardiopagus twins, in those whose livers are
extensively fused, and in those where a significant
bony fusion is to be separated.

63.  Temperature monitoring should aim at normothermia, and
all techniques available should be used to ensure proper
temperature control.
 The use of plastic drapes, padded bandages around the
limbs, and waterproof plastic bandages makes a significant
difference to temperature control during the surgery.
 After each surgical group has operated and the positions
have changed, these measures also need to be moved.
 To facilitate postoperative ventilation, oral tubes may be
changed to nasal tubes at the end of the procedure.

65. Postoperative Care
 Problems in the immediate postoperative period relate to
the consequences of
1. massive blood transfusion,
2. tight closure,
3. prolonged surgery, and
4. alterations in preoperative anatomy.
 Monitoring for bleeding, hypoxia, hypercarbia, acidosis,
hypothermia, hypotension, and electrolyte imbalance is
mandatory.
 Ongoing volume losses, cardiac instability, and
respiratory impairment are common at this time.

66.  When weaning the infants from mechanical
ventilation, attention must be paid to sternal
insufficiency, diaphragmatic dysfunction, and to
the mechanics of breathing.
 Good pain relief is obligatory and may include the
use of intravenous acetaminophen (paracetamol),
which can be given orally or rectally.
 If chronic pain syndromes are anticipated, the early
use of gabapentin should be considered.

67. Prognosis
 Immediate and long-term survival of conjoined
twins is extremely variable.
 Hidden long-term morbidity and mortality occur with
unresolved aspiration after thoracopagus separation;
bronchopneumonia, arrhythmias, and embolic
cerebrovascular pathology.
 Some survivors will be disabled and require lifelong
follow-up care