MECHANICAL VENTILATION WEANING PROTOCOL FOR …

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POST-CARDIAC ARREST HYPOTHERMIA PROTOCOL FOR CRITICAL CARE PATIENTS AT WALTER REED NATIONAL MILITARY MEDICAL CENTERSUBJECT: Poor neurological outcome is common after cardiac arrest. Experimental and animal studies indicate that therapeutic hypothermia may inhibit many of the damaging chemical reactions that follow cerebral anoxia. Multiple studies have demonstrated improved neurological outcomes with the use of induced, mild hypothermia following out-of-hospital cardiac arrest from ventricular fibrillation. Further data suggests other patients with cardiac arrest, such as in-hospital asystolic or PEA arrests, may also derive benefit from induction of mild hypothermia. REFERENCES:Nolan JP, et al. Therapeutic Hypothermia After Cardiac Arrest. ILCOR Advisory Statement. Circulation 2003; 108: 118-121.2005 American Heart Association Guidelines for CPR and Emergency Cardiovascular Care.Bernard SA, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. NEJM 2002; 346: 557-563.The Hypothermia After Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. NEJM 2002; 346: 549-556.Cheung, KW, et al. Systematic review of randomized controlled trials of therapeutic hypothermia as a neuroprotectant in post cardiac arrest patients. CJEM 2006; 8: 329-337.Polderman, KH. Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of a promising treatment modality. Part I: Indications and evidence. Intensive Care Med 2004;30:556-575Polderman, KH. Application of therapeutic hypothermia in the ICU: opportunities and pitfalls of a promising treatment modality. Part 2: Practical aspects and side effects. Intensive Care Med 2004;30:757-769PURPOSE: This SOP outlines the criteria for appropriate selection of patients for mild therapeutic hypothermia and the procedure for induction of mild therapeutic hypothermia. By following this protocol, appropriate patients will be selected for therapy and achieve the target temperature for therapeutic hypothermia. Therefore, the number of patients with good neurological outcome following cardiac arrest should increase. SCOPE: This SOP applies to all physicians and nurses working with comatose patients with return of spontaneous circulation following cardiac arrest in the critical care units of Walter Reed National Military Medical Center.INDICATIONS: Patients with cardiac arrest and return of spontaneous circulation who remain comatose, particularly if initial rhythm was ventricular fibrillation. For purposes of this protocol, comatose is defined as GCS < 9 (either does not follow commands OR does not open eyes to pain) immediately after ROSC.Patients with cardiac arrest of other etiologies should be considered on a case by case basis.Hemodynamic stability with MAP > 60. Use of vasoactive medication is acceptable.Known time of cardiac arrest.CONTRAINDICATIONS:Hemodynamic instability (SBP < 90) despite vasoactive medicationsComa of other etiology (ie drug overdose)Clinically significant bleedingPregnancyHypoxemia (O2 sat < 85%) despite maximal ventilatory supportKnown terminal illnessThrombocytopenia with platelet count < 30k, until corrected.Major head trauma or irreversible neurologic injuryPROCEDURE:Target temperature is 32-34 degrees Celsius. Temperature should be measured continuously by bladder, esophageal, or rectal probes. Temperatures obtained from a pulmonary artery catheter are also acceptable. Typmpanic membrane temperatures are inaccurate in hypothermia and should be avoided. Initial evaluation should include EKG, CXR, CMP, CBC, Coags, abg, and for females < 60 hcg.The goal of cooling should be to obtain the target temperature within 4 hours of ROSC. Cooling should not be delayed for other diagnositic/therapeutic interventions. Cooling should be initiated as soon as possible after ROSC, however patients cooled up to 6 hours after ROSC may still benefit.Therapeutic hypothermia with temperature 32-34 deg C should be continued for 12-24 hours.Acceptable methods of cooling include:Commercially available cooling devices (vests and blankets), ie Artic Sun. Intravascular cooling catheters are also commercially available and considered acceptable, but are not currently available at Walter Reed National Military Medical Center. Ice packs applied to the head, neck, axilla, torso and groin. If ice packs are used, they should be removed once target temperature is obtained, and replaced as needed to maintain target temperature. Decrease temperature of roomUse of HME instead of heated humidifier on ventilatorPatients should be adequately sedated per the Walter Reed National Military Medical Center sedation protocol. Primary agents are midazolam, propofol, and fentanyl.Shivering is associated with increased metabolic demand and must be avoided. Shivering is most profound during induction of hypothermia. Deeper sedation may be required during this time period to prevent shivering. Rapid cooling will minimize shivering during induction.Shivering can be mild (localized to the neck and/or thorax, may be palpable only, may visualize on ECG), moderate (involves gross movement of extremities), or severe (gross movement of trunk, upper and lower extremitiesWarming of distal extremities (hands and feet only) may be effective in preventing shivering. Use of heat packs, blankets, or “bear hugger” (to hands and feet only) are acceptable.Meperidine 50-100 mg iv bolus then 12.5 to 50 mg/hr may prevent shivering. Avoid meperidine in renal failure or with documented seizure. Neuromuscular blockers (ie vecuronium 0.1 mg/kg, then 1 microgram/kg/min titrated to train of fours per protocol) should be used as needed to prevent shivering. Sedation is required with the use of neuromuscular blockade.Other complications of cooling.HypotensionEnsure adequate volume status and utilize vasopressors as indicatedDiuresis may occur with hypothermiaHyperglycemia. Blood glucose should be monitored q6 hrs, with goal blood glucose < 150.Electrolyte abnormalitiesMonitor electrolytes q 4 hrs. Goal serum K is 3.5 to 4.0. Avoid over-aggressive repletion as rebound hyperkalemia is common during rewarming. Stop infusions during rewarming.Replace phos and Mg per routine.ArrythmiasCoagulopathy. Discontinue cooling for clinically significant bleeding. Immunosuprression. Aggressive monitoring for infection is indicated.Rewarming. After the determined period of therapeutic hypothermia (24 hrs), the patient should be allowed to passively return to normothermia. Rate of rewarming should not exceed 0.3 deg C per hour.Turn off artic sun device.Return room temperature to normalResume use of heated humidifier on ventilator, if applicable.Discontinue electrolyte drips.Regular blankets may be used. Heating blankets should be avoided unless temperature is <36 degrees after 12 hours of passive rewarming. Avoid rebound hyperthermia.Ensure adequate volume status as rewarming will cause vasodilation.If using neuromuscular blockers, stop when Temp reaches 36 deg plications of rewarming include hyperkalemia, hypoglycemia, hypotension, shivering. Protocol discontinuation. Certain clinical circumstances reflect severe neurologic devastation following cardiac arrest and may be difficult to recognize during resuscitation and induction of therapeutic hypothermia. If present, consider discontinuation of this protocol and consider withdrawal of life support or limiting further interventions.MyoclonusRefractory hypotension in the setting of rising vasopressor requirements and stress dose steroidsRecurrent cardiac arrestProtocol reviewed and accepted by members of the protocol committee. Robert Browning, MDJessica Bunin, MDCDR, MC, USNMAJ, MC, USAChief, Department of Critical CareChair, Protocol CommitteeWRNMMCInduced Hypothermia After Cardiac ArrestSupplemental DataAlgorithm 1: Criteria, Cautions, and PreparationRationale: Use of hypothermia treatment in patients following cardiac arrest lessens the chance of ischemic brain damage and leads to improved neurological outcomes at 6 months.GOALS / TIMELINEInitiate hypothermia within 6 hours of cardiac arrest.Sustain hypothermia for 24 hours from time of initiation of cooling to a body temperature of 32-34° C(89.6-93.2° F)After 24 hours of cooling, begin rewarming at a rate of 0.3–0.5° C (0.5–0.9° F) every hour up to a target of 36° C (96.8° F)Criteria for Induced HypothermiaCardiac arrest out of hospital, with initial arrest heart rhythm of ventricular fibrillation or pulseless ventricular tachycardia.Cardiac arrest within past 6 hours.Patient intubated with mechanical ventilation.Presence of spontaneous circulation, with or without vasopressor agent a at time of cooling (coma defined here as no purposeful movement to verbal command). - Brainstem reflexes and pathological posturing movements permissible. - Patients with Glasgow Coma Scale (GCS) <9 are eligibleCautionsUse caution in patients with these conditions:Intracranial hemorrhage.Major surgery within 14 days.Systemic infection / sepsis.Known bleeding diathesis or active ongoing bleeding.Temperature less than 30 C after cardiac arrestPreparationAvoid initial rewarming. - Do not actively warm patients who are spontaneously hypothermic following cardiac arrest.Continue other therapies as indicated.Begin treatment early. - Confirm eligibility and gather materials. - Start cooling as early as possible for maximum effectiveness. - Initiate therapy in the ED when possible. - Continue treatment in the cath lab or ICU.Monitor temperature to prevent “overcooling.” - Continuous Temperature Monitoring: Use an esophageal or bladder temperature probe or pulmonary artery temperature probe. - Secondary Temperature Monitoring: Use a secondary temperature device as a safety monitor. Use routine techniques in ICU every 30 minutes during cooling and rewarming, and every hour during maintenance.Algorithm 2: Cooling MethodsProvide Continuous SedationMaintain continuous medication infusion for patient’s comfort and sedation. (Follow ICU Guidelines)Prevent ShiveringSedate the patient during the cooling phase. Consider paralytics if necessary. (Follow interventions for shivering on protocol) - The train-of four method of monitoring neuromuscular blockade is unreliable when the patient is hypothermic, and it is not recommended. - Discontinue paralytic agent infusion once temperature is less than 34? C (93.2? F). If shivering occurs, resume neuromuscular blockade.)Consider Cold FluidsConsider cold saline infusion via a peripheral line or femoral venous catheter to assist in achieving goal temperature. (Cold saline is stored in the emergency department.) - The infusion is 30 ml/kg of 4? C (39.2° F) normal saline over 30 minutes (2 L for a normal-size adult). - Do NOT give cold fluids if there is clinical evidence of CHF or CVP greater than 20. - DO NOT give cold fluid via a jugular or subclavian line.Provide External Cooling with Arctic Sun and IceObtain Ice packsObtain ArcticGel Pads, cables, and one Arctic Sun machine to envelope the patient.Prior to using/setting up electronic cooling device, pack patient in ice (groin, chest, axillae, side of neck) to bring temperature between 32-34? C (89.6-93.2? F). Avoid packing ice on top of the chest, as this may impair chest-wall motion.Once temperature is less than 34? C (93.2? F) and cooling device is ready for use, remove ice bags to prevent excessive drop in patient’s core temperature.Arctic Sun is the electronic external cooling device used at WRAMCMonitor Arterial PressureEnsure an arterial line is placed for arterial pressure monitoring.Algorithm 3: Supportive Therapy and Controlled RewarmingSupportive TherapyTo optimize cerebral perfusion, a mean arterial pressure (MAP) goal of 80-100 mm Hg is preferred. - If MAP less than 80 mm Hg, norepinephrine may be used beginning at 0.1 mcg/kg/min to titrate MAP above 80 mm Hg. - Determine MAP goal by balancing the cardiac safety with the theoretical advantage of higher cerebral perfusion pressure. - Because of peripheral vasoconstriction, BP often remains elevated during hypothermia. - Hypotension (MAP less than 80 mm Hg) from vasodilation is a concern during warming phase.Monitor patient for arrhythmia associated with hypothermia. If persistent, life-threatening dysrhythmias, hemodynamic instability, or bleeding develop, discontinue cooling, and ensure that the patient is actively re-warmed. - Heart rates less than 40 are frequent and are not alone a cause for concern in the absence of other evidence of hemodynamic instability.Obtain Chem 7 and blood gas at time 0. Obtain glucose, K+, and blood gas at hours 6, 12, 18, and 24.Treat potassium values less than 4.0 mEq/L with IV or nasogastric administration of K+ while the patient is being cooled. Stop potassium administration once rewarming begins.Hyperglycemia (> 150) should be avoided. Treat with insulin if elevated. (See IV Insulin Protocols.)Maintain PCO2 in the normal range (35-45 mm Hg).Check skin every two hours for injury caused by ice or cold blankets.Do not provide enteral nutrition during the initiation, maintenance, or re-warming phases of therapy.Controlled RewarmingBegin rewarming 24 hours after initiating cooling.Rewarm at a rate of 0.3–0.5? C (0.5-0.9° F) every hour.Most patients require about eight hours to rewarm.The goal after rewarming is normothermia.Medications During RewarmingMaintain sedation until a temperature of 35° C (95° F) is reached.- If a neuromuscular blocking agent is infusing solely to prevent shivering, discontinue the neuromuscular blocking agent before the sedative/analgesic agents.- Do not discontinue the sedative/analgesic until thepatient is moving or until the neuromuscular blockingagent has been discontinued for at least 3 to 5half lives of the paralytic.Monitor patient for hypotension (secondary to vasodilatation)induced by rewarming.Discontinue potassium infusions.Acetaminophen and external cooling p.r.n. to keeptemperature less than 37.5° C (99.5° F) for 48 hours afteradmissionRewarming with the Arctic Sun DeviceThe goal is to have the patient warm at about 0.3° C(0.5° F) per hour, up to a target of 36°C (96.8° F).Increase water temp by 0.5°C (0.9° F) every 1 to 2hours.Remove the Arctic Sun Gel pads and blankets after a stabletemperature of 36°C (96.8° F) for 1 hour has beenreached.Order Set: ................
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