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BLOOD LOSS

BLOOD LOSS. COLLATERALS IN VERTEBRAL VENOUS PLEXUS. GASTRIC INFLATION, COUGHING, BUCKING, ↑ Paw. SANDBAGS MATTRESSES. PRESSURE ON IVC. BLOOD LOSS. COLLATERALS IN VERTEBRAL VENOUS PLEXUS. ↑↑ BLEEDING. PRESSURE ON IVC. BLOOD LOSS. ANESTHETIC FACTORS. SURGICAL FACTORS:. POSTURAL FACTORS.

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BLOOD LOSS

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  1. BLOOD LOSS COLLATERALS IN VERTEBRAL VENOUS PLEXUS GASTRIC INFLATION, COUGHING, BUCKING, ↑Paw SANDBAGS MATTRESSES PRESSURE ON IVC

  2. BLOOD LOSS COLLATERALS IN VERTEBRAL VENOUS PLEXUS ↑↑ BLEEDING PRESSURE ON IVC

  3. BLOOD LOSS ANESTHETIC FACTORS SURGICAL FACTORS: POSTURAL FACTORS BLOOD LOSS RESPIRATORY FACTORS

  4. BLOOD LOSS SURGICAL FACTORS: • EXTENT OF DISSECTION • DURATION OF SUGERY • SITE AND SIZE OF BONE GRAFT • PREVIOUS SPINAL FUSION • SURGICAL TECHNIQUE • 15-25 mL/kg in uncomplicated spine fusion • with Harrington rods or cotrel-dubousset instrumentation • Massive blood loss: • Anterior posterior spine fusion • Instrumentation into pelvis • Osteotomy of spine to correct rigid abnormalities

  5. BLOOD LOSS ANESTHETIC FACTORS INCREASED ARTERIAL PRESSURE INCREASED PRESSURE ON VERTBRAL VENOUS PLEXUS

  6. BLOOD LOSS POSTURAL FACTORS INCREASED ABDOMINAL WALL TENSION INCREASED INTRA- ABDOMINAL PRESSURE EXTRINSIC PRESSURE

  7. BLOOD LOSS INTERMITTENT POSITIVE PRESSURE VENTILATION INCREASED PRESSURE ON IVC DIVERSION TO VERTEBRAL VENOUS PLEXUS RESPIRATORY FACTORS

  8. BLOOD LOSS: • Calculate MABL • Judicious blood transfusion • Consider alternatives: • Autologous tranfusion • Induced hypotension • Pre-operative Autologous Blood Donation • Normovolemic or hypervolemic hemodilution • Cell salvage

  9. MINIMISING BLOOD LOSS • SURGICAL TECHNIQUE: Sub-periosteal dissection Compressing wound edge with finger tips Packs and retractors • MINIMISE INTRA- ABDOMINAL PRESSURE- (vertebral venous plexus bleeding) Special frames – Relton –Hall frame Adequate muscle relaxation Deep plane of anesthesia Abdomen free of pressure

  10. MINIMISING BLOOD LOSS 3. INFILTRATION WITH EPINEPHRINE: Local vasoconstriction & hydrostatic pressure of fluid volume Maximum dosage with volatile anesthetics- Halothane – 1.0 μg/kg Isoflurane – 3.5 μg/kg (sevo/ des) Enflurane – 5.5 μg/kg Arrhythmias – rare in children

  11. MINIMISING BLOOD LOSS • 5. DELIBERATE HYPOTENSION: • Decreases blood loss by 30-50% when MAP is maintained between 50-60 mmHg. • Concern: Deliberate hypotension reduces SCBF during distraction of spine. • Returns to normal in 35 min. • Hence, distraction no more than 35 min after the start of delberate hypotension. • morbidity of 0.85 per cent • Mortality- between one in 200 and one in 500 patients • Disadvantage- if cardiac arrest or accidental extubation occurs, the patient is in an inappropriate position for therapy

  12. Slowly over 10-15 min • Cerebral, coronary, renal vasodilation • SBP – 75 mmHg • Warning signs: • Excessively dry field • Dark venous blood • Deterioration of SSEPs • Arterial cannulation • U. output – 0.5 mL/kg/hr

  13. Near- normal PaCO2 and SCBF. • PETCO2- reliable estimate of paCO2 in children • Adults – Vd/Vt increases

  14. BLOOD LOSS • 2. Hemodilution – • Upto a hematocrit of 20-25% • Withdraw blood (if isovolemic) • Replace with 3 units crystalloids or 1 unit colloid for every 350 -400 ml of blood withdrawn • Intraop. Assessment of Hb and H‘crit. • Jehovah’s witness

  15. Blood loss 2. PRE-OPERATIVE AUTOLOGOUS BLOOD DONATION: • Replace blood loss with autologous blood • Prevents complications of allogenic blood • IDEAL PATIENT: • Healthy to undergo elective surgery • Likely to need transfusion after surgery • Has Hb > 11g/dL

  16. BLOOD LOSS… • AMERICAN ASSOCIATION OF BLOOD BANKS: • No less than 4 days between donations • No less than 3 days before surgery • Once a week donations for three weeks prior to surgery. • Complications: • Lightheadedness • Vasovagal reaction • Delay surgery • Cost • Inconvenience • Not applicable to Jehovah’s witness

  17. CONTRAINDICATIONS: • Bacteremia • Decreased oxygen delivery( fixed output, anemia, hypoxemia) • Pediatric age group • ?HUMAN ERYTHROPEITIN OR IRON ADJUNCTS • Erythropoeitin: • 600 U/kg twice weekly • 400 U/kg s.c. once a week for 4 weeks (Kulier)

  18. BLOOD LOSS • 3. Cell- salvage: • 50-60% of RBCs can be salvaged • Recover- concentrate- wash- return to patient • Disadvantage- lack of plasma and platelets • INDICATIONS: • Children > 10kg • Blood loss – 20% of blood volume • Procedures in which more than 10% pts are tranfused more than 1 unit blood

  19. CELL SALVAGE ANTICOAGULANT TRANSFUSION (Hcrit- 50 -70%) SALINE WASTE PRODUCTS (WBCs,anticoag, contaminants) STERILE RESERVOIR CENTRIFUGE (5000 rpm)

  20. PROCESSED BLOOD: • Thrombocytopenia • Hypofibrinogenemia • Platelet dysfunction • DIC

  21. CONTRAINDICATIONS: • Extravasated blood > 6 hrs • Excessively hemolysed blood • Bowel contents • Malignant cells • Microfibrillar collagen hemostat • ?Sickle cell anemia • ? Jehovah’s witness

  22. BLOOD LOSS… • 4. Anti-fibrinolytic agents: • Tranexamic acid and EACA: • Hypotension • Cautious during induced hypotension • Better in paediatric patients and neuromuscular disease • DDAVP: • Increases Vwf. • Single dose og 10 mcg/sq.m – dec 30 % loss • Worsen SIADH

  23. AIR EMBOLISM • AIR EMBOLISM: • High risk- 50% • CVC in place • Detection- ETCO2, Bubbling in the wound (1st sign) • Transthoracic doppler ECHO • TEE • Treat- Flood field with saline • Switch of N2O • IV fliuids

  24. EVOKED POTENTIALS SOMATO SENSORY EVOKED POTENTIALS

  25. EVOKED POTENTIALS • SSEPs: • Stimulus: Peripheral nerve • Pathway: Posterior column • Cerebral cortex • EEG scalp electrodes

  26. SSEPs…. • Latency • Amplitude • Increase in latency or decrease in amplitude is taken as surgical injury or ischemia unless proved otherwise • Latency – inc by 10-15% • Amplitude – dec by 50% - CAUSE FOR CONCERN

  27. SSEP… Amplitude Latency

  28. EFFECT OF ANESTHESIA

  29. Motor EVOKED POTENTIALS MOTOR EVOKED POTENTIALS

  30. MEPs • MEPs: • Stimulus: Motor cortex • Pathway:Anterior column • Motor nerve- electromyographic signals, peripheral electrodes, actual limb movements • EEG scalp electrodes

  31. ANESTHETIC REGIMEN • Avoid pre-medication • Induction – short acting drugs, short acting relaxants • Supplemental opioid boluses • Maintenance- 50% N2O + volatile anesthetic 0.25 MAC • Or infusion of etomidate 0.01-0.02 mg/kg/min or propofol 0.1-0.2 mg/kg/min • Discontinue 30 -45 min before testing and continue with etomidate or ketamine infusion at low doses. • Keep TOF at 3-4 • NTG or esmolol infusion – hemodynamic stability

  32. WAKE UP TEST • PRINCIPLE: “Lighten” the anesthetic plane sufficiently to allow the patient follow commands • WHEN TO PERFORM? • Distraction of spinal column • After all instrumentation is in place • PROCEDURE: • Pre- op counselling and rehearsal • Prepare adequate narcotic and i.v. induction agent

  33. Monitor muscle relaxation- allow adequate spontaneous respiration or TOF count of 4 • Reduce inhalational agent to MAC 0.5 • R/O resp. depression by narcotic (?Naloxone) • Command patient to squeeze your hand • Move leg

  34. COMPLICATIONS: • Extubation in prone position • Recall • MI • Self injury • Dislodgement of instrumentation • Air embolism from open venous sinuses

  35. EXTUBATION • INDIVIDUALISED DECISION: • Pre-operative decision • Adult idiopathic scoliosis with mild to moderate PFT abnormailties- EXTUBATION IN OR • PRE- OPERATIVE FACTORS: • Severe PFT derangement- (VC<30% predicted), Abnormal blood gases- MECHANICAL VENTILATION • INTRA OPERATIVE FACTORS: • Pleural nick by surgeon • Antero- lateral or anterior approach • Thoracotomy or lung collapse • Abnormal blood gases

  36. PRE- EXTUBATION FACTORS: • VC> 10mL /kg • TV>3mL/kg • RR spont < 30/min • NIF >-30 cmH2O

  37. POST OPERATIVE CARE • Chest physiotherapy: • Coughing • Deep breathing • Incentive spirometry • Bronchodilators • Pain relief • Multimodal • Systemic- continuos / intermittent/ PCA • Epidural- intermittent/ continous/ PCEA

  38. RESPIRATORY FUNCTION AFTER SCOLIOSIS CORRECTION • Lung volumes – reduced for 1st 10 days • PaO2 – recuced for 2 days • PaCO2 and pH – normal • FRC – normalises on 5th post operative day • Mechanical properties of chest wall • Pain – reduced expansion • Rib configuration • Chest wall edema • Impaired resp. muscle function

  39. Mechanical properties of lungs: • Increased lung water • Increased surface tension • Atelectasis • Inability to cough • Infection

  40. LONG TERM CHANGES • Lung volume – unaltered • Gas – exchange – improved • Dead space – reduced by 40% • Hypoxemia – relieved • Ventilatory equivalent – reduced by 20% • Regional blood flow – improved

  41. SURGICAL CORRECTION

  42. Posterior fixation with harrington rods

  43. CONCERNS: • Pre-incisional infiltration • Sub-periosteal resection • Stripping of erector spinae- • Osteotomy and wedge resection of vertebre • Distraction • Instrumentation

  44. Other approaches • ANTERIOR APPROACH: • Presence of co-existing vertebral anomaly (spina- bifida or hemi- vertebrae) CONCERNS: Blood loss – lesser than posterior approach Full muscle relaxation High FiO2 and selective one-lung ventilation Post-operative hypoventilation Atelectasis Pain Infection

  45. COMBINED APPROACH: • Anterior and posterior • Single or multiple stages • Massive blood loss and repeated positioning

  46. RECENT ADVANCES

  47. LASER SPINE SURGERIES • CO2 laser • Holmium, Nd YAG lasers • Minimal blood loss • Acceptable correction with minimal scarring • Disadvantages: • Expertise • Economic constraints • Laser hazards

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