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Nursing care of patients with Induced Hypothermia

Nursing care of patients with Induced Hypothermia. Danny Chan NO ICU 24/9/2010. Introduction. Numerous studies have been performed in an effort to demonstrate that hypothermia provides neuroprotection to an injured brain, preventing or altering the biological cascade of secondary injury

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Nursing care of patients with Induced Hypothermia

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  1. Nursing care of patients with Induced Hypothermia Danny Chan NO ICU 24/9/2010

  2. Introduction • Numerous studies have been performed in an effort to demonstrate that hypothermia provides neuroprotection to an injured brain, preventing or altering the biological cascade of secondary injury • Hyperthermia appears to be detrimental, worsening the degree of injury produced by the primary and secondary injury processes

  3. Introduction(continue) • Induced hypothermia can be used to protect the brain from post-ischemic and traumaticneurological injury • These side effectscan be serious and, if not properly dealt with, may negate some or all of hypothermia’s potentialbenefits • Many of these side effects can be prevented by careful monitoring of fluid balance, tight control of metabolic aspects such as glucose and electrolyte levels, prevention of infectious complications and various other interventions

  4. Introduction(continue) • The speed and duration of cooling and rate of re-warming are key factors indetermining whether hypothermia will be effective • Nurses need to realize hypothermia’s full therapeutic potential will therefore requiremeticulous attention to the prevention and/or early treatment of side effects, as well as a basicknowledge andunderstanding of the underlying physiological and pathophysiological mechanisms.

  5. Introduction(continue) • Cerebral injury occurs after any condition in whichthere is inadequate blood flow to the brain formore than 5 min. • Cerebral ischemia producesa cascade of effects including ATP energy depletion,ion pump failure, release of free radicalsand excitotoxic agents such as glutamate andcalcium • The formationof free radicals and release of glutamateinto theextracellular space are proportional tothe intraischemic temperature.

  6. Effects of therapeutichypothermia • retardation ofdestructive enzymatic reactions • suppression offree-radicals reactions • reduction of the oxygen demand in low-flow regions • reduction of intracellular acidosis • inhibition of the biosynthesis, and release and uptake of excitatory neurotransmitters • improves oxygen supply to areas of ischemic brain and decreases intracranial pressure (ICP) • attenuated the ischemia-induced striatal glutamate and dopamine release during reperfusion,therefore reducing brain damage, ischemic neurons and excitotoxic processes

  7. Non-invasivetechniques of therapeutichypothermia • Cooling blanketsAir-filledWater-circulating • Ice packs • Caps of helmetsAir-filledWater-circulating • Immersion incold-water • Self-adhesive hydrogel-coated cooling pads

  8. Methods of cooling ( Non invasive) External cooling methods: • ice packs, coolingblankets, wet towels and cooling helmets • simple to use, widely available and may beused in the pre-hospital setting • generally slow at reducing core temperatureand it is difficult to control the core temperature when the target is reached.

  9. Methods of cooling( Non invasive) • Complications, such as arrhythmias and infection, are more common if the temperaturereduces below 30 ℃. • Control of re-warming is also difficult.

  10. External cooling methods Gaymar MEDITHERM 3 PATIENT COOLING / REWARMING THERAPEUTIC HYPOTHERMIA unit

  11. Invasive techniques of therapeutichypothermia • Infusion of cold IV fluidsRinger’s lactate/ Saline • Retrograde jugular vein flush • Extracorporeal circulatingcooled bloodCardiopulmonary bypass Femoral-carotid bypass • Nasal, nasogastric andrectal lavage • Peritoneal lavage withcold exchanges

  12. Methods of cooling (Invasive) Intravascular cooling methods: • with heat exchange catheters provides an effective method ofreducing body temperature, and maintaining it within the desired range. • a closed loop heat exchange device placed in the inferior vena cava, followed by control warming. • enables tightercontrol of core temperature and allows slow, controlled re-warming

  13. Intravascular cooling methods • ALSIUS cooling catheter • CoolGard 3000® thermal regulation system

  14. Clinical paper Larsson, Wallin & Rubertsson (2010) Cold saline infusion and ice packs alone are effective in inducing andmaintaining therapeutic hypothermia after cardiac arrestResuscitation 81,15-19 Cooling methods • Pt was given 4℃ NS IV of 30ml/kg at 100 ml/min via two IV catheters • Covered ice packs ( NS infusion bags 250 ml ) applied in groins, axillae and along the neck • Change/remove the ice pack PRN to keep core temp. 32-34 ℃ • Cooling duration - 24 hr • Passive rewarming to 36 ℃ over 8 hr

  15. Discussion • cold saline infusioncombined with ice packs was found to be effective in inducingand maintaining therapeutic hypothermia and also in controlling rewarming • all patients in the study (n = 38) reached the target temperatureof 32–34 ◦C, on average 4.4 h from cardiac arrest and3.4 h after initiation of hypothermia treatment • the target temperature remained stableduring maintenance of hypothermia treatment with only minorinterventions, consisting either of application of ice packs whenthe temperature started to rise above 33.5 ◦C or removal of the icepacks when it fell below 32.5 ◦C.

  16. Discussion • the infusion of cooled saline solution was targeted to a volumeof 30 ml/kg and a rate of 100 ml/min to induce hypothermia • did not result in any clinical signs of right heartfailure or pulmonary oedema in any of the patients • cooling below the target temperature range did occur but was not a major problem • the temperaturewasmonitoredcontinuously and recorded every 15 min during hypothermia treatmentand rewarming • the rewarming time was 8.2 h and not exceeding 0.5 ℃/hr • additional sedation was given or ice packs re-applied in an effort to prevent too fast rewarming The method is feasible in clinical practice at low cost and should be considered as an alternative to other methods of planned hypothermia treatment

  17. Hypothermia protocols St. Mary’s Hospital NevadaUSA • Inclusion Criteria-> 18 yrs.-Cardiac arrest with ROSC-Persistent coma with GCS < 9-BP > or = 90 mmHg • Exclusion Criteria-Pregnancy-CPR > 45 min or downtime >10 min-Severe coagulopathy-Other causes of coma

  18. Hypothermia protocols Cooling and rewarming protocals • Initiate cooling with iced NS gastric lavage and ice packs on pt’s axilla and groin until cooling blanket started • Place the cooling blanket according to instruction • Select ‘Manual’ mode on the cooling machine to 5℃ till pt’s core temp to 33 ℃ (will take 3-8 hrs)

  19. Hypothermia protocols • Then select ‘Auto’ and set the target temp to 33 ℃ • After 24 hrs, rewarm passively to 36.5 ℃ by setting the machine to ‘Manual’ mode and reset unit by increasing target temp by 1℃ every 2-4 hrs • Stop all K+ supplement 8 hrs prior to rewarming – prevent rebound hyperkalemia • Maintain complete sedation and paralysis as prescribed

  20. Hypothermia protocols BP and Volume management • SBP >90 mmHg, MAP >80 mmHg to maintain cerebral perfusion Medication and fluids • NS 100 mL/hr • Inotropes to maintain MAP> 80 mmHg • Stop all K+ administration 8 hrs prior to rewarming

  21. Hypothermia protocols Sedation • Titrate Propofol / Midazolam accordingly to BIS reading 40-60 Paralysis • Vecuronium to suppress shivering • Discontinue paralytic after pt is warmed to 36.5 ℃

  22. Nursing interventions • VAP preventive measures • DVT prophylaxis • PUD prophylaxis • Laboratory blood test

  23. Effects of therapeutic hypothermia • Hypothermia activates the sympathetic nervous system causing vasoconstriction and shivering. • Shivering increases oxygen (O2) consumption by 40-100% which is undesirable in the post hypoxic pt. • Hypothermia shifts the oxyhemoglobin curve to the left and may result in decreased O2 delivery.

  24. Effects of therapeutic hypothermia • Elderly pts will cool more quickly than younger or obese pts. • Initiating paralysis in a pt who is already hypothermia should be avoided -> can result in a precipitous drop in core body temp.

  25. Effects of therapeutic hypothermia • Hypothermia shifts the oxyhemoglobin curve to the left and may result in decreased O2 delivery. • However, the metabolic rate is also lowered, decreasing O2 consumption/ carbon dioxide (CO2) production. • Ventilator settings may need to be adjusted due to decreased CO2 production, using temperature corrected blood gases.

  26. Effects of therapeutic hypothermia • Hypothermia initially causes sinus tachycardia, then bradycardia. 1. Extremely important to keep temp >30ºC. 2. Temperatures: a. <30º C, increased risk for arrhythmias. b. <28º C, increased risk for ventricular fibrillation. • Severely hypothermic myocardium (<30°C) is less responsive to defibrillation and medications

  27. Effects of therapeutic hypothermia • Hypothermia decreases cardiac output and increases systemic vascular resistance (SVR). • Hypothermia can induce coagulopathy which is treatable with platelets and fresh frozen plasma • Hypothermia-induced diuresis is to be expected and should be treated aggressively with fluid and electrolyte repletion. Magnesium, phosphorus and potassium should be monitored closely and maintained in the normal range.

  28. Effects of therapeutic hypothermia • Decreased insulin secretion and sensitivity leads to hyperglycemia, which should be treated aggressively. • Re-warming must proceed slowly over 6-8 hours to prevent vasodilation, hypotension, and rapid fluid and electrolyte shifts.

  29. Complications of Hypothermia • Pneumonia • Cardiac arrthymias • Hypovolemia • Electrolyte disorders • Insulin resistance • Decreased insuline secretion • Thrombocytopenia • Leukocytopenia • Metabolic acidosis • Impaired coagulation • Shivering • Hiccups

  30. Monitoring • Goal is to maintain patient’s core temperature between 32° and 34°C for 24 hours. a. If temp < 31° C, consider infusing 250 ml boluses of warm 40°C IV NS or LR untiltemperature > 32°C. b. Monitor closely for arrhythmias whentemperature < 32°C.

  31. Monitoring • Hemodynamic Assessment: • Continuous SaO2 monitoring • Maintain MAP 65-120 mmHg with IV fluids, vasopressors, or nitrates as ordered.

  32. Monitoring Laboratory tests: • ABG, RFT, CBC, Clotting, Ca, PO4, • Blood glucose Urine output: • Hypothermia-induced diuresis is common. • Aggressive IV fluid repletion may be required.

  33. Re-warming • Begin re-warming 24 hours after target temperature reached • Re-warming too rapidly can cause vasodilatation, hypotension, and rapid electrolyte shift

  34. Re-warming Prior to rewarming: • Volume load aggressively with Normal Saline to compensate for reductions in BP, Scv02, and central venous pressure (CVP). • K+ shifts to extra cellular compartment during re-warming. • STOP all K+ containing fluids • However, always correct hypokalemia, and other electrolytes, to the normal range.

  35. Re-warming • Re-warmed gradually in a controlled manner to avoid vasodilatation and hypotension. • Goal is to re-warm the patient over 6-8 hours. • Increase Cooling blanket setting by 0.5°C every 1 to 2 hour.

  36. Re-warming • Assess vital signs • Monitor K+ every 4 hours and more frequently if needed • Monitor serum glucose levels closely as insulin resistance resolves, increased risk for hypoglycemia. • Follow ABGs as needed (temperature corrected) Adjust ventilator settings accordingly

  37. Re-warming • Anticipate reduction in venous return (cardiac output) and BP, as cooler blood shifts from core to extremities. Aggressive IV fluids may be necessary to maintain adequate volume status during re-warming. • Maintain paralysis until patient temperature > 36°C. Once temperature > 36°C, paralysis can be stopped. Titrate sedation to comfort and ventilator synchrony.

  38. Conclusion • Evidences suggested that hypothermia can be used to prevent or limit damage to the injured brain • It is important to induce hypothermia as quickly as possible, as protection appears to be greater when cooling is initiated early • The successful application of hypothermia requires the use of strict protocols, vigilance and close attention to the prevention of side effects • Some major side effects such as: hypovolemia, hypotension, electrolyte disorders, arrhythmias, hyperglycemia, bleeding complications, infection need to be monitoring closely and treated promptly • The best coolingtechnique is one that is easy to use and at thesame time effective.

  39. References • Laura H. Mcilvoy(2005)The Effect of Hypothermia andHyperthermia on Acute Brain InjuryAACN Clinical IssuesVol. 16, No. 4,pp. 488–500 • Nursing practice manual (2007) Post Cardiac Arrest Therapeutic Hypothermia Hospital of the University of Pennsylvania Nov • K. H. Polderman (2004) Application of therapeutic hypothermia in the intensive care unit Intensive Care Medicine • I Larsson, E Wallin, S Rubertsson (2010) Cold saline infusion and ice packs alone are effective in inducing and maintaining therapeutic hypothermia after cardiac arrest Resuscitation 81 (2010) 15–19 • A Alzaga, M Cerdan, J Varon (2006) Therapeutic hypothermia Resuscitation 70,369-380 • T.M. Kozik (2007) Induced Hypothermia for Pt with Cardiac Arrest Critical Care Nurse Vol.26 No.5 OCT

  40. Thank You

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