NEUROSURGICAL ANESTHESIA

1. NEUROSURGICAL ANESTHESIA BY MOHGA ADEL (MD)

2. CASE STUDY A 65-year-old,male sustains minor head trauma ,He has a transient syncopal episode after the trauma, Three days later he presents in the ER with a history of vomiting and confusion. An emergency craniotomy is scheduled patient data were as follows: BP170/90,HR48,T38C, BUN55

3. OUR OUTLINE • URGENCY: This case is urgent although vital signs are highly suggestive of elevated ICP that will require surgical treatment the surgeon will require CT scan unless the patient neurological status is deteriorating. • So there is Some time for optimizing the patient medical condition

4. Reason for the exam • Differential diagnosis of signs and symptoms in life threatening scenario. • Conflicting therapies are possible. However, protecting the brain and managing complications are the major focus in this question

5. PREOPERATIVE QUESTIONS: What are the signs and symptoms of increased intracranial pressure? • Headache ,vomiting without nausea ,altered mental status(lethergy, confusion),and papilledema. Hypertension and bradycardia are classic symptoms of Cushing response to seriously elevated ICP • Obtundation ,focal neurological finding and hemodynamic instability are late finding that indicate uncal hernation

6. What are the funoscopic finding of ICP? • Papilledema is swelling and obliteration of the normal optic disc as due to back pressure and swelling of the optic nerve from increased ICP

7. What are the significance of papillary dilatation in a patient with head trauma? • Unilateral then bilateral papillary dilation (elliptical shape )are focal neurological finding that signal downward herniation of the Uncas through the tentorium of the brain with pressure exerted on cranial nerve III

8. Would you delay the operation for C-spine films in this patient ? Why and why not? • Assuming the patient has a normal airway and is able to respond appropriately to pain, in addition to lack of tenderness on the cervical spine it is very unlikely that the patient will have any fracture in the spine • If the patient neurological condition is not deteriorating so go for C-spine film, if not then intubate while doing traction,Dont wait for C spine film • Awake fibro optic intubation with potential for coughing and gagging would significantly increase ICP so judge the case

9. The patient become agitated in CT scanner what would you suggest? • Red flags if you suggest sedation without accompanying the patient in the CT scanner. it is a fatal mistake • Agitation can be a sign of deterioration of the neurological status ,hypoxemia or hemodynamic instability. • Sedation obscure the neurologic exam Surgical intervention may be necessary without the CT scan

10. What is the significance of elevated BP? should it be treated ? Why and why not? • The BP is up in this case for a reason ,the patient with increased ICP has reflex bradycardia so if you decrease the blood pressure you are lowering the cerebral perfusion pressure • CPP=MAP-ICP as ICP is increased so keep the BP high to maintain the CPP

11. Is your management altered by temperature of 38 ? • The elevated temperature increases the patient cerebral metabolic rate ,and o2 consumption ,give acetaminophen ,don’t warm the IV fluids or the room ,Check chest X ray he may have pneumonia from aspiration

12. Why is the BUN is elevated? How would you differentiate between perenal and renal azotemia? • A lot of things may cause this ,dehydration from vomiting ,preexisting intrinsic renal disease ,obstructive uropathy or reabsorbtion of hematoma all may cause elevated BUN • Old labs are of values, if it is a recent event don’t be in a miss, it is dehydration from vomiting ,confirm your diagnosis by blood gases and potassium level • You excpect hypokalemic ,hypocholermic metabolic alkalosis with a BUN/CR ratio>20/1

13. How would you differentiate between perenal and renal azotemia? • First the patient clinical condition, dehydration ,hypotention,low cardiac output suggest prerenal • BUN/CR ratio>20/1 • Fractional excretion of Na<1mmole • Urine Na<10 mmole as the kidney try to conserve Na in prerenal state • Vital signs are vital all are given to you for a reason

14. If grand mal seizure activity occurs what to do? • If grand mal seizure happened so bad thing is happening ,induce anesthesia at once with whatever monitors are available. • Grand mal increases ICP and CMRo2 • Hyper ventilate to pCo2(25-30)mmHg ,give lasix and mannitol, elevate head 30 degree • Steroids has nothing to do in head injury it is a vasogenic edema not cytotoxic

15. An arterial blood gases reveals,PH (7.54)pco2(34)po2(85)?interpret? What would you expect Cl level to be? • It represent mixed metabolic and respiratory alkalosis • Spontaneous hyperventilation is likely as a response to increased intracranial pressure • The metabolic component is due to vomiting with loss of K and hydrogen ions in vomits the Cl level will be low as result of excess bicarbonate

16. Would you place nasogastric tube in this patient? • No I would not ,gagging during its introduction will increase the ICP so this outweigh the benefit ,NG tube also tend to decrease the effectiveness of the oesephagogastric junction during rapid sequence induction

17. Intra operative question:How would you induce this patient? • Panthenol and rocuronium with lidocaine premedication ,panthenol decrease the CMRo2 rocuronium,is fast acting and haemodynamically neutral,lidocaine prevent rise of ICP with induction • If there was any concern about difficult airway use succsinylcholine it will prevent rise in ICP • Intubation should be rapid sequence in flexion position

18. What monitors would you use ,what fluid would you use? Do you use Glucose replacement? • In addition to routine ASA monitors including ETCO2 .capnography is now considered routine by most practitioner . • We would place a Foley cath ,arterial line multifocal CVP if no cardiac disease no need for PA cath.pericordial Doppler for surgeries where head is higher than the heart. • Any fluids can be given crystalloid or colloid you can use ringers or hetastarch.it is important that fluid used shouldn’t be hypotonic or contain dextrose to prevent elevation of ICP

19. Do you need special monitors during vessel clamping? • Parenchymal brain tissue Po2 electrode (Pbro2) is used for monitoring brain oxygenation during clamping • The brain oxygenation will be affected by retractors pressure rather than drugs and techniques causing reduction to both CMR and CBF,so using this monitor is not a novel during vascular clamping,you can depend on body Pao2

20. A right craniotomy is performed .During operation the patient acutely developed severe hypotention,and tachycardia what is your diagnosis? • The most common causes of acute hypotension is air embolism, other causes are anesthesia overdose ,hypovolemia and anaphylaxis • The diagnosis of venous air embolism is by transoesphegeal eco, pericardial Doppler ,end tidal nitrogen ,drop in end tidal Co2 ,increase in arterial to end tidalCo2gradient,increase in pulmonary artery pressure,ECG pattern of right heart strain, hemodynamic collapse

21. What is the treatment of venous air embolism? • Support circulation, give 100%O2 ,flood the wound with water, head down ,put the patient on the right side, take air from pulmonary outflow track and relieve the obstruction aspirate through CVP,raise CVP by fluid load be ready for CPR,avoid PEEP to prevent paradoxical air embolism through a patent foramen oval

22. Is invasive ICP monitoring necessary in this patient ? • ICP monitoring is important in this case Ventriculostomy is good choices sampling of CSF is available and can be used for drainage of CSF if ICP increases • Subdural bolt is pressure monitor only • The risks of ICP monitoring are tissue damage during placement and infection

23. What are the new techniques for cerebrovascularautoregulation monitoring(CVA)? • Continuous monitoring of CVA is through the use of pressure reactivity index PRx • It is a moving linear correlation coefficient between MAP and ICP • It is a good guide in optimizing the CPP in traumatic brain injury(CPPopt),it provides an important information regarding long term outcome a PRx above 0.2 threshold and CPP below CPPopt range are associated with worse outcome

24. THANK YOU