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

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Presentation on theme: "PRESSURE ON IVC COLLATERALS IN VERTEBRAL VENOUS PLEXUS SANDBAGS MATTRESSES GASTRIC INFLATION, COUGHING, BUCKING, ↑ Paw."— Presentation transcript:

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2 PRESSURE ON IVC COLLATERALS IN VERTEBRAL VENOUS PLEXUS SANDBAGS MATTRESSES GASTRIC INFLATION, COUGHING, BUCKING, ↑ Paw

3 PRESSURE ON IVC COLLATERALS IN VERTEBRAL VENOUS PLEXUS ↑↑ BLEEDING

4 BLOOD LOSS POSTURAL FACTORS ANESTHETIC FACTORS SURGICAL FACTORS: RESPIRATORY FACTORS

5 SURGICAL FACTORS: EXTENT OF DISSECTION DURATION OF SUGERY SITE AND SIZE OF BONE GRAFT PREVIOUS SPINAL FUSION SURGICAL TECHNIQUE 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

6 ANESTHETIC FACTORS INCREASED ARTERIAL PRESSURE INCREASED PRESSURE ON VERTBRAL VENOUS PLEXUS

7 POSTURAL FACTORS INCREASED ABDOMINAL WALL TENSION INCREASED INTRA- ABDOMINAL PRESSURE EXTRINSIC PRESSURE

8 RESPIRATORY FACTORS INTERMITTENT POSITIVE PRESSURE VENTILATION INCREASED PRESSURE ON IVC DIVERSION TO VERTEBRAL VENOUS PLEXUS

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

10 1. SURGICAL TECHNIQUE: Sub-periosteal dissection Compressing wound edge with finger tips Packs and retractors 2. MINIMISE INTRA- ABDOMINAL PRESSURE- (vertebral venous plexus bleeding) Special frames – Relton –Hall frame Adequate muscle relaxation Deep plane of anesthesia Abdomen free of pressure

11 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

12  5. DELIBERATE HYPOTENSION:  Decreases blood loss by 30-50% when MAP is maintained between 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

13 INHALATIO NAL GANGLION BLOCKERS DIRECT ACTING VD Ca CHANNEL BLOCKERS Β - BLOCKERS Use as adjunct. sole agents: 1.myocardi al function Impaired. 2.Unsatisfac tory control 3.Sluggish return of BP 4.Longer latency - wake up tests and SSEP Disadvantag es: Reflex tachycardia by barorecepto rs Counteracts hypotension Tachyphylax is Resistant hypotension Rebound hypertensio n At comparable levels of hypotension, NTG produced lesser blood loss than SNP. Lower venous pressure with NTG Nicardipine: Context sensitive t ½ = 1-8 hrs Cannot revert BP promptly on stopping infusion Reflex tachycardia PPl – 0.06 mg/kg Esmolol- 500 mcg/kg/mi n Rapid onset, short titratable duration, Cardioselec tive

14  Slowly over 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

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

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

17 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

18  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

19  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)

20  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

21 ANTICOAGULANT STERILE RESERVOIR CENTRIFUGE (5000 rpm) SALINE WASTE PRODUCTS (WBCs,anticoag, contaminants) TRANSFUSION (Hcrit %)

22  PROCESSED BLOOD:  Thrombocytopenia  Hypofibrinogenemia  Platelet dysfunction  DIC

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

24  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

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

26 SOMATO SENSORY EVOKED POTENTIALS

27  SSEPs:  Stimulus: Peripheral nerve  Pathway: Posterior column  Cerebral cortex  EEG scalp electrodes

28  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

29 Latency Amplitude

30 DRUGLATENCYAMPLITUDE INHALATIONALS ↑↓ Barbiturates, BZDs ↑↓ Propofol ↑ 0 Fentanyl, morphine ↑↓ Sufentanil, Alfentanil0 ↓ Meperidine ↑↓ N2O, midazolam0 ↓ Etomidate ↑↑ Ketamine0 ↑

31 MOTOR EVOKED POTENTIALS

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33  MEPs:  Stimulus: Motor cortex  Pathway:Anterior column  Motor nerve- electromyographic signals, peripheral electrodes, actual limb movements  EEG scalp electrodes

34  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 mg/kg/min or propofol mg/kg/min  Discontinue min before testing and continue with etomidate or ketamine infusion at low doses.  Keep TOF at 3-4  NTG or esmolol infusion – hemodynamic stability

35  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

36  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

37  COMPLICATIONS:  Extubation in prone position  Recall  MI  Self injury  Dislodgement of instrumentation  Air embolism from open venous sinuses

38  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

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

40  Chest physiotherapy:  Coughing  Deep breathing  Incentive spirometry  Bronchodilators  Pain relief  Multimodal  Systemic- continuos / intermittent/ PCA  Epidural- intermittent/ continous/ PCEA

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

42  Mechanical properties of lungs:  Increased lung water  Increased surface tension  Atelectasis  Inability to cough  Infection

43  Lung volume – unaltered  Gas – exchange – improved  Dead space – reduced by 40%  Hypoxemia – relieved  Ventilatory equivalent – reduced by 20%  Regional blood flow – improved

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46 CONCERNS: 1.Pre-incisional infiltration 2.Sub-periosteal resection 3.Stripping of erector spinae- 4.Osteotomy and wedge resection of vertebre 5.Distraction 6.Instrumentation

47  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

48  COMBINED APPROACH:  Anterior and posterior  Single or multiple stages  Massive blood loss and repeated positioning

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50  CO2 laser  Holmium, Nd YAG lasers  Minimal blood loss  Acceptable correction with minimal scarring  Disadvantages:  Expertise  Economic constraints  Laser hazards

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52  Higher mental functions  GCS  Pupils  Cranial nerves  Sensory  Motor  Reflexes  Bowel and bladder  Peripheral nerves

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55  Miller’s Anesthesia 7 th ed  Stoelting’s Anesthesia and Co existing disease  Problem oriented Anesthesiology –Yao  Pediatric Anesthesia- Gregory 4 th ed.  Handbook of Neuroanesthesia – Cotrell 3 rd ed  a contribution to the pathological anatomy ofscoliosis f. Beely J Bone Joint Surg Am. 1891;s1-4:  Anaesthesia for spinal surgery in adults D. A. Raw, J. K. Beattie and J. M. Hunter British Journal of Anaesthesia 91 (6): 886±904  Spine Sugery: Comlpications and how to prevent them


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