Thermoregulation Issues: A Review of Normothermia Guidelines and MH

Transcription

1 Thermoregulation Issues: A Review of Normothermia Guidelines and MH Terry Clifford, MSN, RN, CPAN ASPAN President Mercy Hospital, Portland, Maine

2 OBJECTIVES Part I: Hypothermia Risk Factors Consequences Interventions Part II: Review MH History Etiology S&S Treatment Management

3 ASPAN S EVIDENCE-BASED CLINICAL PRACTICE GUIDELINE FOR THE PROMOTION OF PERIOPERATIVE NORMOTHERMIA

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5 First developed in 1998, published in 2000 Consensus Conference in Bethesda Maryland Multidisciplinary EBP goal, to improve patient outcomes through the maintenance of normothermia Revision 2/08 foiled by snow! Revision completed 10/08 to be published 10/09

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7 Scope and Significance of the Condition Every patient undergoing surgery is at risk for developing perioperative hypothermia.

8 Negative Consequences Patient discomfort from shivering. Shivering is most important!! Physiological consequences of shivering include: increased O 2 demands CV system strain patient dissatisfaction

9 Negative Consequences Low temps cause adrenergic stimulation with a resultant increase in serum catecholamine levels. Increases in heart rate, BP, glucose levels, general sympathetic nervous system reactions Altered drug metabolism. Core hypothermia prolongs the time it takes to recover the first twitch in the TOF Hypothermic patients require longer periods of time to metabolize anesthetics

10 Negative Consequences Impaired wound healing with increased susceptibility to infection. Normothermic patients got infections 64% less often than colder patients The functionality of neutrophils and phagocytes (which fight infection) was significantly reduced intraoperatively Considered contributing cause of hypothermia induced reduction in resistance to infection Intraoperative hypothermia can induce suppression of immune function!! Elective hernia repair, varicose vein surgery, or breast surgery

11 Negative Consequences Increased length of PACU, ICU, and hospital stay. Hypothermic required 40 more minutes than normothermic to reach target score in PACU Patients in the normothermic group were discharged from the hospital 40% earlier and spent 43% less time in the ICU Increased red blood cell (RBC), plasma, and platelet infusions Impaired platelet function and reduced effectiveness of the coagulation pathway. Significant increase in transfusions in the hypothermic group (P<.05) or 86% more units

12 Negative Consequences Increased need for mechanical ventilation. Normothermic patients need mechanical ventilation 34% less often than colder patients. Increased cardiac problems and associated costs. Adverse outcomes included cardiac arrhythmias, increased SVR, decreased cardiac output, and leftward shift of the oxyhemoglobin curve. Outcomes include organ dysfunction, prolonged hospital stay, hypoperfusion, and mortality

13 Pathophysiology a b c 26 C 28 C 28.5 C 29.5 C d

14 Classes and levels of evidence Class I: The benefit far outweighs the risk and the recommendation should be performed or administered. Class IIa: The benefit outweighs the risk and it is reasonable to perform or administer the recommendation. Class IIb: The benefit is equal to the risk and it is not unreasonable to perform or administer the recommendation. Class III: The risk outweighs the benefit and the recommendation should not be performed or administered. Level A: Evidence from multiple randomized trials or meta-analysis evaluating multiple populations with general consistency of direction and magnitude of effect. Level B: Evidence from single randomized trials or non-randomized studies evaluating limited populations. Level C: Evidence from case studies, standards of care, or expert opinion involving very limited populations.

15 Contributing risk factors Risk Factors Supported by Strong Evidence There were no risk factors supported by strong evidence. Risk Factors Supported By Weak Evidence (Class IIa or IIb, Level B) Age (Class IIa, Level B) Systolic blood pressure (Class IIa, Level B) preoperative systolic blood pressure less than 140 more likely to develop hypothermia postoperatively Female gender (Class IIb, Level B) Level of spinal block (Class IIb, Level B)

16 Contributing risk factors Risk Factors Supported By Insufficient Evidence (Class IIa or IIb, Level C) BMI below normal (Class IIa, Level C) Normal BMI (Class IIb, Level C) Procedural duration (Class IIb, Level C) Body surface/wound area uncovered (Class IIb, Level C) Anesthesia duration (Class IIb, Level C) History of diabetes with autonomic dysfunction (Class IIb/Level C)

17 Temperature Measurements Temperature Measurement Recommendations Supported by Strong Evidence Near-core measures of oral temperature best approximates core (Class 1, Level B) The same route of temperature measurement should be used throughout the perianesthesia period for comparison purposes (Class 1, Level C) Caution should be taken in interpreting extreme values (< 35 0 C, > 39 0 C) from any site with near-core instruments (Class 1, Level C)

18 Temperature Measurements Temperature Measurement Recommendations Supported by Weak Evidence Temporal artery measurements approximate core temperature at normothermic temperatures but not extremes outside of normothermia (Class IIb, Level C) Infrared tympanic thermometry does not provide accurate temperature measurements during the perianesthesia period (Class 11b, Level B) Temperature Measurement Recommendations Supported by Conflicting Evidence Oral chemical dot thermometers are acceptable near-core alternatives (Class 1, Level B)

19 Equivalency Chart

20 Preadmission /Preoperative Recommendations Assessment Assess for risk factors for perioperative hypothermia (Class I, Level C) Measure patient temperature on admission (Class I, Level C) Determine patient s thermal comfort level (Class I, Level C) Assess for signs and symptoms of hypothermia (e.g. shivering, piloerection, and/or cold extremities (Class I, Level C) Document and communicate all risk factor assessment findings to all members of the anesthesia/surgical team. (Class I, Level A)

21 Preadmission /Preoperative Recommendations Interventions Implement passive thermal care measures (Class I, Level B) Maintain ambient room temperature at or above 24 C or 75 F. (Class I, Level C) Institute active warming for patients who are hypothermic. (Class IIb, Level B) Consider preoperative warming to reduce the risk of intra/postoperative hypothermia (Class IIb, Level B) Evidence suggests prewarming for a minimum of 30 minutes may reduce the risk of subsequent hypothermia

22 Intraoperative Recommendations Assessment: Identify patient s risk factors for unplanned perioperative hypothermia (Class I, Level C) Frequent intraoperative temperature monitoring should be considered in all cases. (Class I, Level C) Assess for signs and symptoms of hypothermia (Class IIb, Level C) Determine patient s thermal comfort level (Class IIb, Level C) Document and communicate all risk factor assessment findings to all members of the anesthesia/surgical team. (Class I, Level A)

23 Intraoperative Recommendations Interventions All patients should receive the following: Limit skin exposure to lower ambient environmental temperatures (Class I/Level C) Initiate passive warming measures (Class I/Level C). Passive warming interventions include: cotton blankets, surgical drapes, plastic sheeting and reflective composites ( space blankets ). Maintain ambient room temperature from C based on AORN and architectural recommendations. (Class I/Level C) Patients undergoing a procedure with an anticipated anesthesia time > 30 minutes (Class I/Level C), who are hypothermic preoperatively (Class I/Level A), and/or patients at risk for hypothermia (Class I/Level C) Active warming should be implemented (Class I/Level A)

24 Intraoperative Recommendations Special Notation: While one study evaluating the use of forcedair warming devices compared its use according to the manufacturer s recommendations versus placing the forced air warming device between two standard hospital blankets did not report any thermal injuries, this technique should never be used as it falls outside of the parameters of manufacturer recommendations (Class III/Level C).

25 Intraoperative Recommendations There is evidence to suggest that alternative active warming measures may maintain normothermia when used alone or in combination with forced air warming (Class IIb/Level B). These warming measures include: Warmed IV fluids (Class IIa/ Level B) Warmed irrigation fluids (Class IIb/ Level B) Circulating water garments (Class IIb/Level B) Circulating water mattresses (Class IIb/ Level B) Radiant heat (Class IIb/ Level B) Gel pad (Arctic Sun ) surface warming (Class IIa/ Level B) Resistive heating (Class IIa/ Level B)

26 Phase I/II PACU Postoperative Patient Management Recommendations Assessment Identify the patient s risk factors for perioperative hypothermia (Class I, Level C) Document and communicate all risk factor assessment findings to all members of the healthcare team. (Class I, Level A) Measure patient temperature on admission to the PACU (Class I, Level C) If normothermic, continue to measure temperature at least hourly, at discharge, and as indicated by patient condition (Class I, Level C) If hypothermic, measure temperature at a minimum of every 15 minutes until normothermia is achieved (Class I, Level C) Determine patient s thermal comfort level (Class I, Level C) Assess for signs and symptoms of hypothermia (e.g. shivering, piloerection, and/or cold extremities) (Class I, Level C)

27 Phase I/II PACU Postoperative Patient Management Recommendations Interventions If the patient is normothermic: Institute thermal comfort measures: Implement passive thermal care measures (Class I, Level C) Maintain ambient room temperature at or above 24 C or 75 F (Class I, Level C) Assess patient thermal comfort level on admission, discharge, and more frequently as indicated (Class I, Level C) Observe for signs and symptoms of hypothermia (e.g. shivering, piloerection, and/or cold extremities) (Class I, Level C) Reassess temperature if patient s thermal comfort level changes and/or signs or symptoms of hypothermia occur (Class I, Level C) Implement active warming measures as indicated Measure patient temperature prior to discharge (Class I, Level C) If the patient is hypothermic: In addition to normothermic interventions, initiate active warming measures: Apply forced air warming system (Class I, Level A) Consider adjuvant measures: Warmed intravenous fluids (Class IIb, Level B) Humidified warm oxygen (Class IIb, Level C) Assess temperature and thermal comfort level every 15 minutes until normothermia is achieved (Class I, Level C)

28 Phase I/II PACU Postoperative Patient Management Recommendations Discharge teaching: Instruct the patient and responsible adult of methods to maintain normothermia after discharge (e.g. warm liquids, blankets, socks, increased clothing, increased room temperature) (Class I, Level C)

29 Multidisciplinary Problem Managing hypothermia requires the coordinated efforts of anesthesia providers, Surgeons, perioperative, perianesthesia, and critical care nurses.

30 ASA ( Normothermia should be a goal during emergence and recovery. When available, forced air warming systems should be used for treating hypothermia. Hypothermia = adverse consequences increased susceptibility to infection, impaired coagulation and increased transfusion requirements cardiovascular stress and cardiac complications, postanesthetic shivering and thermal discomfort. Forced air convection warming systems are effective for restoring temp to > than or equal to 36 o C (or 96.8 o F)

31 AORN ( Unplanned hypothermia can cause serious patient problems. Even mild hypothermia (ie, temperature < 36 o C [< 96.8 o F]) has been consistently linked with perioperative patient complications, including * shivering, * wound infections, * cardiovascular ischemia, * coagulopathy, * altered drug metabolism, and * prolonged postoperative recovery.

32 Limitations NEW monitoring devices such as the Temporal Artery Thermometer The current research is ADULT based The guideline is based on routine surgery not on critical care or trauma cases

33 Warming Things Up Warming devices that are commonly available include warmed cotton blankets, thermal drapes, fluid warmers, water mattresses forced air warming systems. Meta analysis regarding warming methods showed forced air warming systems the most effective method (comfort AND satisfaction)

34 Malignant Hyperthermia

35 What is MH? MH is an inherited disorder of skeletal muscle MH is usually triggered by inhalation agents and/or succinylcholine Results in hypermetabolic state with muscle damage, hyperthermia and death if untreated.

36 History of MH In 1960 a young man, Mr. Proband, in Australia refused general anesthesia to set a broken leg because he knew that 10 of his family members mysteriously died in the OR After this case, Denborough and Lovell described MH in literature ANESTHETIC DEATHS IN A FAMILY [ 62] 1970/71 Caffeine Halothane contracture test identified 1970s Relation of masseter muscle rigidity to MH realized 1971 First International Symposium on MH in Toronto, CA

37 History of MH 1979 Dantrolene identified as antidote received FDA approval 1980s End tidal CO2 identified as an early sign 1982 National society formed establishing the MH hotline 1987/88 North American (NA) MH Registry 1995 MHAUS & NA MH Registry merge 1990 s to 2000 s Genetic testing continues

38 Etiology The condition involves regulation of intracellular Ca + Ryanodine receptor/mediator (releases Ca + in Ca + channel) is most commonly involved Exposure to certain anesthetic agents causes an abnormal release of Ca + This results in a sustained muscle contraction and the abnormal increase in energy utilization and heat production. Muscle cells eventually run out of energy, and die, and release large amounts of potassium into the bloodstream, which can lead to heart rhythm abnormalities. Can cause cardiac arrest, kidney failure, blood coagulation problems, internal hemorrhage, brain injury, liver failure, and may be fatal.

39 Etiology Summarized

40 Incidence Most patients are aware of family hx Inherited component; autosomal dominant (only need to get the abnormal gene from one parent in order to inherit the disease) More common Europeans (northern) Incidence is 1:10,000 to 1:50,000 patients Mean age for MH is 15 Reactions tend to occur at extremes of age Before Dantrolene, mortality rate was approximately 80%. Since Dantrolene, mortality rate is approximately 10% Some patients can receive triggering agents and

41 Triggering Agents for MH Pharmacologic agents Non trigger agents Opioids Halothane Sevoflurane Non depolarizing muscle relaxants Isoflurane Ketamine Desflurane Propofol Succinylcholine Anxiolytics Possibly also triggered by heat & exercise Nitrous oxide

42 Signs of MH Increased metabolism, manifested as increased CO 2 production, increased minute ventilation, and elevated end tidal CO 2. Increased oxygen consumption manifested by decreased mixed venous oxygen, hypoxia, cyanosis, and mottling. Tachypnea (only seen with spontaneous ventilation). If ventilation is controlled, the need to increase minute ventilation to maintain end tidal CO 2 at a given level can be a valuable early sign. Tachycardia (may progress to other dysrhythmias). Rigidity is the most unique sign of MH, but is not the most constant. Fever/profuse sweating. Fever is a late sign because metabolic events in muscle have overcame the body s ability to dissipate the heat, so the rate of rise may be very rapid. Acidosis (respiratory and metabolic). Muscle damage. Myoglobinuria/myoglobinemia, creatine kinase elevation, hyperkalemia, hypercalcemia, and hyperphosphatemia.

43 Signs of MH Muscle rigidity may or may not be present early sign: end tidal CO2 late sign: temp MH may occur at any point during an anesthetic even on emergence and LATER in PACU May reoccur despite treatment

44 Diagnosis of MH GOLD STANDARD: Caffeine/Halothane contracture test (CHCT) using muscle biopsy $6, not covered by insurance Must go to the center because sample has to be FRESH Newer Genetics looking for mutation of the calcium channel receptor RYR 1 hits only 30% of MH positive so far

45 Muscle Biopsy Centers 1. University of Minnesota Minneapolis, MN 2. Uniformed Services University of the Health Sciences Bethesda, MD 3. University of California Davis, CA 4. University of California Los Angeles, CA 5. Wake Forest University Winston Salem, NC

46 Immediate Therapy of MH Discontinue triggering agents Hyperventilate with oxygen Get help!! Dantrolene 2.5 mg/kg push. Must dilute 20 mg bottle with 60 ml DW. Continue for hours Initate aggressive cooling of patient Do not give calcium channel blockers Labs as necessary for K+, myoglobin

47 Immediate Therapy of MH Place a second large bore IV for rapid cool fluid administration Insertion of a Foley catheter, NGT, rectal tube Bicarbonate may be administered for a severe metabolic acidosis (ph 6.55) Glucose, insulin, and calcium carbonate may be given for elevated serum potassium Make arrangements for an emergent intensive care unit (ICU) bed

48 Shelf life of three years from the date of manufacture Dantrolene is like a defibrillator; it is kept ready for use at all times, even though the need is rare. The cost of maintaining 36 vials in stock is approximately $909 per year, $76/month or $2.51/day a tiny fraction of most facility budgets and a very small price to pay for safety.

49 **Now there s a generic choice that works every bit as well at a price that s much more appealing. Introducing Dantrolene Sodium for Injection from US World Meds.

50 Prevention of MH Good preop history: Hx of MH susceptibility, muscle diseases, family anesthesia problems CO 2 and temperature monitoring during anesthesia Recognition of masseter rigidity Investigation of unexplained tachycardia, hypercarbia and hyperthermia

51 Prevention of MH Use succinylcholine only when indicated Avoid triggering agents in MH susceptible patients Have dantrolene available in any location using general anesthesia

52 Preparation for MH Susceptible Patient Disable vaporizers Flush system for 20 min with 10 l/min oxygen; change CO 2 absorber Hide succinylcholine!! Use non triggering anesthesia agents Have dantrolene available Monitor in PACU for at least 2 hours

53 Anesthesia for MH Proven Anxiolytic Propofol narcotic induction Non depolarizing muscle relaxants (mivacurium, rocuronium, vecuronium, atracurium) Maintenance with nitrous narcotic propofolrelaxant technique Reversal of muscle relaxant Observe for 4 hours

54 North American MH Hotline Emergency: MH HYPER 24/7 Routine: MHAUS Registry:

55 Future Developments Additional work on genetics and genetic testing Better dantrolene (the current formulation is hard to dissolve) Better understanding of pathophysiology

56 What Can YOU do? Identify location and contents of the MH Cart Who maintains this cart? Stocks it? Review interventions as annual competency Run Mock Codes!!! Stat page anesthesia Activate internal code system Obtain MH cart Contact kitchen for buckets of ice Notify CCU of pending transfer Notify surgeon/physician Mixers for Dantrolene. Support Cooling measures Obtain labs, EKG, outputs

57 Date: Time: Surgeon MDA RN RN RN Age: Location: Surgery: CRNA RN RN RN INTERVENTION TIME INITIAL INTERVENTION TIME INITIAL Patient weight: Discontinue Anesthesia Correct Acidosis Change Soda Lime Administer Sod. Bicarb 1-2 meq/kg Flush tubing & machine with 100% O 2 Treat Arrhythmias (no calcium blockers) Hyperventilate with 100% oxygen Lidocaine 1 mg/kg IV Mix Dantrolene Secure Monitoring Administer 2.5 mg/kg IV Dantrolene Arterial Line Cooling measures (stop when temp 38C) CVP Call kitchen for ice Preserve Renal Function Ice major arteries (groin, axillae, neck) Maintain IVs at 2 8 ml/kg (get frozen IV bags from OR) Insert NG tube/ice lavage with NS Furosemide 50 mg IV (up to 4 doses) Insert Foley/ice lavage with NS Treat Hyperkalemia Insert Rectal tube/ice lavage with NS Reg. Insulin 10units in 10 ml Dextrose and H 2 O via IV Hang cold IV solutions Transfer to CCU Obtain ABG LABS Obtain Lytes EKG Glu BU Cal- Phosphoru LFT SGO LD CP **After MA hours: HG Page HC Clinical Plt Thyro- Advisor Lactat - N ciu s s T H K ( ) G B T xin e cose m Results Repeat Values Pt PT T Urine Myoglobins

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