fluid management in neurosurgical pts.pptx

Fluid management in neuro surgical cases

1. Fluid management during neurosurgery Presenter- Dr. Surya Kant Moderator- dr. Ashutosh kaushal

2. INTRODUCTION AIM OF THERAPY- Early detection & correction of fluid abnormalities which helps in the preservation & restoration of neurologic function; however, these patients may be volume depleted due to diuretic therapy; intraoperatively they are exposed to the vasodilatory effects of potent anesthetic agents, third space losses, perioperative volume losses. GOAL OF INITIAL FLUID THERAPY Maintenance of normovolemia and as a result cerebral and spinal cord perfusion pressures is maintained. Restore intravascular volume Optimize hemodynamics Maintain tissue perfusion, integrity and function.

3. PHYSIOLOGY Fluid movements between vasculature and tissues: Earnest starling described the forces that determine the movement of water between vasculature and tissues, which was formalized subsequently into starling equation, as follows: Qf = kfs [(pc−pt)−δ (πc−πt)] Where, Qf = net amount of fluid that moves between the capillaries and the surrounding extracellular space Kf = filtration coefficient for the membrane, S is the surface area of the membrane, pc is the hydrostatic pressure in the capillary membrane, pt is the hydrostatic pressure of the surrounding tissue, δ is the coefficient of reflection that can vary from 1=no movement to 0=free diffusion of the solute across the membrane, πc is the oncotic pressure of the plasma, And πt = oncotic pressure of the fluid in the extracellular space.

4. FLUID MOVEMENTS BETWEEN THE CAPILLARIES AND THE BRAIN

5. CHOICE OF FLUIDS

6. crystalloids Iso-osmolar crystalloids are given at a rate sufficient to replace the patient’s urine output and insensible losses. Hypo-osmolar and dextrose-containing solutions should be avoided . Blood loss is replaced at about 3:1 ratio (crystalloid/blood) down to a hematocrit of approx 25–30%, depending on the rate of hemorrhage and the patient’s physical status. Patients with SAH are more likely to suffer from cerebral infarction if their intravascular volume and sodium are not adequately replaced. Hypotonic solutions should be avoided in neurosurgical patients and TBI patients(Grade 1C). A slight reduction in plasma osmolality by 1mOsm/L increases the pressure of fluid shifts across the BBB to 19  mmHg .

7. Furthermore, a decline in plasma osmolality by 3% leads to overt cerebral edema with a 30% reduction in intracranial blood CSF volume. Strong ion difference (SID), calculated as the sum of all ions, should be taken into consideration in patients undergoing neurosurgical procedures, due to its effect on pH.   Administration of fluids with a SID of zero , such as 0.9% sodium chloride (NaCl), induces metabolic acidosis . Administration of fluids with SID >40 ( plasmalyte A) induces metabolic alkalosis . Chloride-rich solutions may induce hyperchloremic acidosis, associated with impaired renal blood flow. Maintaining euvolemia is important as any disorders in renal blood flow may lead to AKI.

8. Hyperchloremia is also associated with increased 30-day mortality and LOS in non-cardiac surgical patients. Evidence also suggests that chloride-rich fluids contribute to delayed recovery of gut function and reduced gastric blood flow, which may stimulate postoperative vomiting and subsequent increases in ICP. Therefore, treatment with BSS is preferred over 0.9% NaCl in patients undergoing neurosurgical procedures. NS can affect coagulation parameters , increasing activation of natural anticoagulation in the brain that results in activated fibrinolysis in serum and upregulation of vascular adhesion molecule expression in the injured brain. It has been suggested to use an infusion of NS or HS in hypovolemic TBI patients with metabolic alkalosis . The administration of saline solutions corrects volume deficit and acid-balance disorders via induction of metabolic acidosis, while HS has the added advantage of potentially reducing ICP.

9. Balanced salt solution Some crystalloids are buffered and termed balanced solutions. A buffer is a partially neutralized acid that resists changes in pH.   Citrate , a crystalloid buffer, binds intravascular ionized calcium, thus stimulating coagulation disorders . Use of large volumes of such fluids may cause serious problems, particularly when rapidly infused during sudden perioperative bleeding. Their composition more closely resembles intravascular fluid . Balanced crystalloids do not affect acid-base balance to the same degree and have a lower incidence of hyperchloremic acidosis, peri-operative AKI, electrolyte disturbances, need for blood transfusion, and systemic inflammation. In TBI patients, the administration of BSS did not affect ICP, SID, phosphate, Na, or Cl levels, unlike saline solutions. BSS is also more effective treatment of hypovolemia-induced acidosis .

10. HyperTONIC sALINE Used as a resuscitation fluid in hemorrhagic hypovolemia. As an osmotherapeutic agent reducing brain edema or elevated ICP. Osmotically shift water from the interstitial and intracellular spaces of the CNS to the intravascular space. Additionally, it reduces CSF production. Hypertonic saline can be administered as a bolus or continuous infusion. Dose can be titrated according to serum sodium levels and/or serum osmolality. Frequent serum sodium checks every 4–6 hours are recommended. The sodium load and consequent hypernatremia may be a concern in patients with neurologic injury who are at risk for seizures and who may have altered mental status due to an underlying injury.

11. Dextrose solutions Hyperglycemia has been associated with worsened neurologic outcome and/or mortality after TBI, AIS, SAH and ICH. Probable hypothesis : Glucose loading provides additional substrate for the production of lactic acid during the ischemic period. This increased intracellular lactate is thought to be neurotoxic, resulting in neuronal death. By enhancing glutamate release in the neocortex.

12. studies A post hoc analysis of data from the IHAST study showed that patients with glucose levels >129mg/dL at the time of aneurysm clipping had more cognitive impairment at 3  months compared to normoglycemic patients . In the NICE-SUGAR trial (Intensive control group, target glucose 81–108mg/dL Vs conventional control group, target glucose ≤180mg/ dL), mortality at 90 days was higher in the intensive-control group (27.5%) compared to the conventional-control group (24.9). The incidence of severe hypoglycemia (glucose ≤40mg/dL) was also higher in the intensive control group . New single or multiple organ failure and hospital or ICU lengths of stay were no different between the groups.

13. mannitol Use: when significant brain swelling occurs or when it becomes necessary to decrease brain volume to facilitate exposure and thereby reduce brain retractor ischemia. It should be given only after other potential causes of increased brain volume have been considered ( eg , hypercapnia, vasodilators, obstruction to venous outflow). Current guidelines recommend mannitol at the dose of 0.25–1 g/kg as basic hyperosmotic therapy in patients with ICH. It should preferably be used in patients with low plasma osmolality, and avoided when plasma osmolality > 320  mOsm /kg H2O . 

14. In addition to the increase in plasma osmolality, there can be a decrease in serum sodium and bicarbonate concentrations (osmotically induced expansion of ECF), or hyperkalemia (maximum mean increase: 1.5mmol/L, due to solvent drag or hemolysis). Contraindication : patients with ESRD or severe CHF. Biphasic effect on ICP : Concomitant with the infusion, ICP may transiently increase (vasodilation of cerebral vessels in response to the sudden increase in plasma osmolality). A subsequent reduction in ICP occur by the movement of water from the brain’s interstitial and intracellular spaces into the vasculature.

15. colloids Hetastarch : It is a 6% solution of hydroxyethyl starch (HES) in normal (0.9%) saline. HES is an enzymatically hydrolyzed amylopectin , which is chemically modified by hydroxy- ethylation of glucose subunits at carbon positions C2, C3 or C6. The metabolism and plasma clearance of HES is determined by the molecular weight, degree of molar hydroxyethyl substitution and the pattern of this substitution (C2/ C6 ratio). HES with lower MW, molar substitution, and C2/ C6 ratio are degraded faster , resulting in faster renal elimination, shorter volume effect, and fewer adverse effects on coagulation.

16. recommendations The European Medicines Agency: HES solutions must no longer be used to treat patients with sepsis or burn injuries or critically ill patients because of an increased risk of kidney injury and mortality. HES solutions may still be used for fluid resuscitation in addition to crystalloids in patients with acute blood loss ; their use should be limited to 24 hours with renal function monitoring. FDA : HES products not be used in critically ill patients or in patients with pre-existing renal dysfunction. Based on current evidence, the use of HES is not recommended until it is clearly demonstrated that such products provide benefit in the neurosurgical patient and do not cause harm when infused in limited volumes.

17. dextran Dextran solutions are colloids composed of glucose polymers with predominantly 1–6 glycosidic linkages. Both dextran 40 and 70 are hyperosmolar ; and thus can actually draw water from the interstitial into the intravascular compartment. Adverse effects : Interfere with normal blood coagulation . Allergic and pseudoallergic reactions. Interfere with blood typing and cross-matching. Interfere with blood glucose, bilirubin, and protein measurement. Acute renal failure is reported following the overzealous administration of dextran 40.

18. Red blood cells RBCs should be given only to keep hematocrit at a “safe” level . This level varies from patient to patient ; and even in a specific circumstance, it may be difficult to objectively define what constitutes “safe.” Oxygen delivery to the tissues is maximal at a hematocrit of approx 30%. At higher hematocrit, oxygen delivery is compromised by increased blood viscosity, whereas at hematocrits < 25% , delivery decreases because of reduced oxygen carrying capacity of the blood. Healthy individuals show signs of cognitive impairment with Hb below 7 g/dL and may tolerate low levels of hematocrit (20–25%) without complications when undergoing elective surgery. Evidence from studies of patients who are critically ill but without serious cardiac disease, supports a restrictive transfusion strategy (hemoglobin ~ 7 g/dL).

19. There is a large variability in transfusion triggers for patients with TBI, AIS, ICH and SAH and studies show that both anemia and RBC transfusion may negatively influence outcome . In patients with spontaneous ICH, anemia has been an independent predictor of hematoma size and is associated with poor outcomes. Anemia in ischemic stroke is linked with stroke deterioration and poor outcome, and is also an independent predictor of mortality. Anemia in SAH has been associated with a worse outcome regardless of WFNS, modified Fisher score or vasospasm. In patients with high-grade SAH, Hb < 9gm/L is associated with risk of increased brain hypoxia, cell energy dysfunction and impaired auto-regulation.

20. plasma Plasma should only be administered to correct coagulation defect caused by deficiency of the coagulation factors. Volume expansion is no longer considered an appropriate use of this blood product. Coagulation defects may arise in neurosurgical patients for a variety of reasons. Abnormality in the PT, aPTT , or platelet count may be present in around 55% of head injury patients at admission. Victims of TBI may require massive fluid resuscitation because of hemorrhagic hypovolemia. If this initial fluid resuscitation is achieved with asanguinous fluids, a dilutional coagulopathy may aggravate a preexisting clotting disorder.

21. albumin In a retrospective study of patients with SAH, there was a higher proportion of patients with good outcomes at 3 months in the albumin group than in the non-albumin group, although there was no significant difference in the incidence of symptomatic vasospasm. However, the SAFE trial , a multicenter, randomized, double-blinded trial, compared 4% albumin and NS in critically ill patients and showed no significant difference in mortality, proportions of organ failures, duration of ICU stay and hospital stay, duration of mechanical ventilation, and duration of RRT. However, in the subgroup analysis, the RR of death of trauma patients in the albumin group compared to the saline group (RR = 1.36) was higher than that in the patients without trauma (RR = 0.96). The difference in RR of death was because more brain injury patients were assigned to the albumin group than to the saline group.

22. A post-hoc analysis of a subgroup of patients with TBI in the SAFE trial, the SAFE-TBI study , showed that the 2-year mortality of patients with severe brain injury was significantly higher in the albumin group than in the saline group. Increased ICP may have contributed to the high mortality in the albumin group . The results of the SAFE trial and post-hoc analysis continue to influence albumin use in patients with TBI. Limitations of SAFE-TBI trial: The mortality of TBI patients was not the primary endpoint, and the trial design was not randomized for TBI analysis . 4% human albumin is a hypo-osmolar solution that may potentially increase the ICP and cause cerebral edema The Albumin in Subarachnoid Hemorrhage (ALISAH trial) , designed to determine the feasibility and safety of albumin in SAH patients, was terminated as serious complication of pulmonary edema were reported.

23. Patients receiving 1.25 g/kg/d of 25% albumin for 7 days demonstrated better neurological outcomes than those receiving a lower dose (0.625 g/kg). Follow-up analysis of the ALISAH trial showed that higher doses of albumin (1.875 g/kg and 2.5 g/kg) were associated with a lower incidence of vasospasm, DCI, and cerebral infarction. However, these results should be interpreted with caution: The said trial had an inadequate sample size and insufficient power . The Albumin therapy for acute ischemic stroke ( ALIAS pilot trial) suggested that high-dose albumin therapy (1.37 to 2.05 g/kg of 25% albumin) has potential neuroprotective effects after AIS. ALIAS part 1 trial was suspended after safety analysis revealed an increased incidence of pulmonary edema and mortality .

24. ALIAS part 2 trial , which was modified by adding exclusion criteria and safety measures, was also suspended because of the high incidence of pulmonary edema in the albumin group. Pooled data analysis from ALIAS part 1 and 2 trials showed no difference in the 90-day neurological outcomes and mortality between the 25% albumin and saline groups. However, there was an increased risk of pulmonary edema and ICH in the patients administered with albumin 25% at 2 g/kg. Based on this evidence, the European Society of Intensive Care Medicine ( ESICM ) recommends against the use of high-dose albumin in patients with AIS and the use of low- (4%) or high-dose (20–25%) albumin in neurointensive care patients.

25. Fluid administration during craniotomy Preoperative deficits: For the nonfebrile adult patient, daily water loss averages approx 100mL/h. Fluid loss can occur by nasogastric suction, diarrhea, emesis, and phlebotomy. Respiratory and insensible losses are higher in patients who are febrile from any cause in the preoperative period

26. Hemodynamic goals Goal of perioperative fluid management : optimize the circulatory system with adequate CBF, maintain an adequate CO, and avoid excessive fluid loading. Analysis of continuous invasive arterial BP has been frequently criticized when used as the only method for evaluating volume status in neurosurgical patient. Goal directed therapy has been recommended for patients undergoing neurosurgical procedures Rapid and uncontrolled infusion of fluids immediately after induction of anesthesia may negatively affect local, tumor-related brain edema in fluid-unresponsive patients. Similarly, it may also result in iatrogenic hemodilution in patients receiving hyperosmolar therapy in the preoperative period. Iatrogenic hemodilution may further induce dilutional coagulopathy leading to increased surgical bleeding and increased use of intraoperative blood transfusion.

27. Dynamic hemodynamic parameters such as PPV, SVV, pleth variability index ( PVi ), and delta down during positive-pressure ventilation are thought to provide a more accurate picture of volume status and responsiveness to fluid expansion. SVV is a sensitive predictor of fluid responsiveness , especially in patients receiving hyperosmotic therapy in the perioperative period. SVV is also a sensitive predictor of fluid responsiveness before and during brain surgery and can more sensitively predict an increase of > 10% in the SV compared to MAP, HR, CO, and CVP. The target of the SVV of GDFT can affect clinical outcomes for supratentorial brain tumor resection. Comparing two GDFT regimens for supratentorial tumor resection (with threshold SVV values set at 10 for the low SVV group and at 18 for the high SVV group), the low SVV group had lower postoperative serum lactate levels, shorter length of ICU stay, and a lower incidence of postoperative neurologic events than the high SVV group.

28. Comparing the GDFT group managed fluid by hemodynamic parameters (including SVV) with a control group managed fluid by the therapeutic decision of the anesthesiologist, the former had less administered fluids, shorter length of ICU stay, lower ICU costs, and lower lactate levels than the control group. The PPV and PVI have also been reported to be good predictors of fluid reactivity during brain surgery. Between the CVP group, which maintained a CVP of 5–10 cmH2O, and the PPV group, which maintained a PPV below 13%, in patients undergoing a brain tumor surgery, the latter had better postoperative hemodynamic stability and less postoperative fluid requirement. The PPV-guided GDFT during supratentorial tumor resection had a comparable brain relaxation scale, low serum lactate levels, more intra operative fluids, and higher urine output than the standard care group .

29. Fluid management in specific conditions Traumatic Brain Injury: Main goal: to restore and maintain adequate CPP. Perioperative hypotension has been observed in 36–65% of patients undergoing emergency craniotomy following TBI. BSS should be the first line choice to correct hemodynamic instability (in patients who remain fluid responsive). HS solutions have been used successfully to treat hypovolemia and intracranial hypertension. Hypotonic and glucose containing solutions should be avoided . Synthetic colloids can be used together with crystalloids, guided by plasma AKI biomarkers. Inotropic support should be added in all cases with fluid unresponsive hypotension.

30. Brain tumour surgeries Primary goal : maintain preoperative MAP during the intraoperative and early postoperative period. Maintain normovolemia and normotension. Rapid changes in mean and diastolic BP, fluid balance, and length of surgery are all independently associated with perioperative cerebral infarct size and overall survival after elective brain tumor surgery . An elevated plasma osmolality following preoperative hyperosmotic therapy significantly limits the use of hypertonic crystalloids during the perioperative period. Glucose containing or hypotonic solutions should be avoided . The use of BSS seems be the best option for initial fluid resuscitation, since colloids impair coagulation during and after surgery . Colloids may impair kidney function , especially in patients receiving mannitol in the preoperative period. Hematocrit should be kept > 28%.

31. Cerebral aneurysm surgeries Goal: To maintain normovolemia before aneurism clipping and slight hypervolumia after clipping . Glucose containing or hypo osmolar solutions should be avoided . Physiological solutions like BSS or NS is best preferred. The use of colloids in patients with SAH is associated with increased inflammatory responses , more requirements for blood transfusion, and altered cerebral autoregulation when compared to those treated with BSS. Hetastarch should not be used or used sparingly (<500 ml).

32. Commonly encountered fluid abnormalities

33. management SIADH- Free water restriction sufficient to reduce total body water by 0.5-1 L /day . Demeclocycline & lithium antagonize the renal actions of ADH in refractory cases. Neurologic symptoms with profound hyponatremia( S.Na <115-120 meq /l) require aggressive therapy. 3% saline @1-2ml/kg/h ( indicated in pts. who have seizures or who develop signs of water intoxication) to increase S.Na by 1-2meq/l/h & should be monitored every 1-2h to avoid over correction. Cerebral salt wasting syndrome- Rapid restoration of the blood volume & recommended fluid for resuscitation is 0.9% saline.

34. Diabetes insipidus- Central d.i - Requires exogenous replacement of ADH with either desmopressin or aqueous vasopressin . 1-4 mcg s/c every 12-24h or intra nasally at a dose 5 times larger . PARTIAL D.I- Chlorpropamide 250-750 mg/day; clofibrate 250-500mg/6-8h or carbamazepine 400-1000mg/day. NEPHROGENIC D.I- Restricting Na & water intake & Hydrochlorothiazide to 50-100 mg/day.

35. Which fluid to choose ? Remain controversial The slight hypo-osmotic nature of the buffered Ringer solutions does harm in this context is debatable . The viable alternative is isotonic saline, which causes metabolic acidosis & plasmalyte , which still requires a full elucidation of its place in neurosurgery. Mannitol & hypertonic saline should be reserved for treatment of raised ICP & not as routine resuscitation fluids in neurotrauma & neurosurgery. Crystalloid fluid volumes > 3L – prolong GI recovery time after the surgery & volumes upto 6L- increase the risk of impaired wound healing, bleeding, pulmonary congestion & pulmonary edema .

36. Therefore, a rational decision is to start compensating the ongoing hemorrhage with a colloid fluid when 3L of crystalloid fluid has been infused . >1.5L colloid fluid volumes per day should be avoided due to their effects on the coagulation system. By that time, the trigger for transfusing erythrocytes has usually been reached in any case. Albumin and gelatin are currently the most reliable choices among the colloid fluids. However, these preparations are generally not favored in trauma 24 and more specifically, isotonic saline gives a better outcome than albumin when used in neurotrauma.25

37. In the intensive care setting, no superiority is evident for crystalloid over colloid fluid therapy when evaluated after 30days.26 Starch has been shown to cause kidney injury in patients with sepsis , while neither albumin nor gelatin seems to cause this problem.27,28 There is still no firm evidence of starch causing harm when used in the operating room . To ensure optimal perfusion to all body regions during surgery, the anesthetist might individualize the fluid treatment by monitoring the urinary excretion and the central hemodynamics . A technique called “ goal-directed fluid therapy ” implies that repeated bolus infusions of 200–300mL of a colloid fluid are given until the increase in stroke volume for each bolus is less than 10%. Once this occurs, further fluid infusions are futile because they will only act to decrease oxygen delivery by diluting the hemoglobin concentration without increasing cardiac output.14,29

38. conclusion The choice of fluid during neurosurgical procedures depends largely on the patient’s clinical condition, particularly renal function . BSS are a good first choice to restore and/or maintain intravascular volume and hemodynamic stability and is superior to normal saline. Generally, NS should be avoided; however HS solutions can be administrated in selected patients, guided by plasma electrolyte concentrations and acid-base balance. Hypotonic solutions and colloids (HES) should be avoided . Fluids should be treated as drugs , always considering the dose and duration of administration, and moving toward de-escalation when no longer needed. Fluid administration should be guided by dynamic variables assessing fluid responsiveness .

39. Extra edge Urea and glycerol are now rarely used because over time they penetrate the BBB and may cause worsening of ICH hours after their initial beneficial effect. Intravenous administration of mannitol has also been associated with the leakage into white matter near gliomas possibly due to the changes in BBB permeability near tumors . Mannitol leak may exacerbate peritumoral edema and lead to ICP rebound. Although survival has been reported with serum sodium levels as high as 202mEq/L , acute increases to values that exceed 170mEq/L are likely to result in a depressed level of consciousness or seizures. Intensive glucose control (target < 110mg/dL) carries a definite risk of hypoglycemia and may be harmful in the critically ill patient. Evidence is accumulating, however, that tighter glucose control may improve neurologic outcome and lower risk of infections, especially in patients with SAH.

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