1. 1. PRESENTOR: Dr.Kumar MODERATOR : Dr.chaitanya kumar
2. 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. 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.
4. 4. 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.
5. 5. 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.
6. 6. 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."
7. 7. 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.
8. 8. 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.
9. 9. 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
10. 10. 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
11. 11. 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..
12. 12. 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.
13. 13. Conjunctions Always involving the Umbilicus (Midline Conjunctions) I- Thoracopagus II- Cephalopagus III- Parapagus IV- Ischopagus V- Omphalopagus
14. 14. 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.
15. 15. 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
16. 16. Pygopagus Joined at the sacrum, Incidence is about 19% of all conjoined twins. Separation is possible. The survival rate is high.
17. 17. 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.
18. 18. 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.
19. 19. 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
20. 20. 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.
21. 21. 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.
22. 22. 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.
23. 23. 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.
24. 24. 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.
25. 25. 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.
26. 26. 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.
27. 27. 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.
28. 28. 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 .
29. 29. 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.
30. 30. 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.
31. 31. 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.
32. 32. 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.
33. 33. 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.
34. 34. 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.
35. 35. 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.
36. 36. 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.
37. 37. 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
38. 38. 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
39. 39. 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.
40. 40. 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.
41. 41. 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
42. 42. 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.
43. 43. 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.
44. 44. Premedication Sedative or anxiolytic premedication is generally not required. In older sets of twins, sedation options include midazolam, chloral hydrateeach 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.
45. 45. 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.
46. 46. 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).
47. 47. Color coding
48. 48. 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
49. 49. 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 infants 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.
50. 50. 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.
51. 51. 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.
52. 52. 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.
53. 53. 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