Hypothermia: Take the Chill Off

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Hypothermia Take the Chill Off

• Susan Fossum BSN, RN, CPAN
• ASPAN Immediate Past President
• IARNA Oct 2008

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Objectives

• Describe the thermoregulatory process
• Identify the risk factors for hypothermia
• Identify strategies for management of Unplanned
  Hypothermia
• Discuss ASPANs Hypothermia Clinical Guideline

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Hypothermia Concerns

• Focused efforts on patient safety, elimination of
  preventable surgical complications
• Joint Commission
• Institute of Healthcare Imp (5 million lives)
• WHO World Health Organization
• Every patient at risk 70 estimate
• memorable experience

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Physiology of Normothermia

• Balance of heat production vs heat loss
• Body heat byproduct of bodys metabolic
  processes cellular metabolism - muscle
• Regulation - Negative feedback system in the CNS
  hypothalamus - change of lt1C core vs skin
  temp set point activated
• Voluntary Involuntary

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Thermoregulation

• Thermoreceptors skin, nose, oral cavity visera,
  spinal cord
• Physiologic responses- vasomotor tone
• 2 thermal compartments
• - core (head, trunk)
• - periphery (extremities)
• Core temperature narrow range (36 - 38C)
• Each patient has unique baseline core temp
  preop temp reference point

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Perioperative Induced or Unplanned Perioperative
Hypothermia

• Heat loss during any procedure
• bring in / strip down ?Preventative measures
• Dependent on environment / anesthetic induced
  situation
• Interthreshold range increases 20 times over
  set point with induction
• Redistribution of heat core to periphery
  unplanned hypothermia

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Definitions

• Normothermia 36C - 38C
• Hypothermia defined as a core temperature lt36C
  
• Three levels
• Mild 32C to 36C
• Moderate 30C to 32C
• Severe lt 30C
• forgotten VS

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Mechanisms of Heat Loss
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Radiation

• Loss of heat transfer between 2 surfaces of
  different temps (no contact)
• Accounts for 40-60 of heat loss
• Problematic in OR cold rooms (lt21C)
• Most vulnerable elderly, neonates

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Convection

• Heat loss to circulating air currents gradient
  between body/air
• wind chill factor
• 25-50 heat loss
• Ventilation systems/air exchanges
• Laminar flow

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Conduction

• Physical contact with another object - warm
  surface meets cold surface transfer of heat
• Cold table, IV fluids, blood, cold irrigants,
  prep solutions, cold sheets/drapes
• 10 of heat loss

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Evaporation

• Heat transfer insensible water loss (fluid to
  gas)
• Perspiration
• Ventilation
• Exposed viscera
• Evaporation of skin prep (alcohol based)
• 25 of heat loss

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Unplanned Perioperative Hypothermia

• Culprits GA / Regional anesthesia
• 3 phases redistribution, linear decrease,
  thermal plateau
• Redistribution 1C within 30 min induction,
  continues for first hour (1 - 5C)
• Linear slow decrease during second hours (heat
  loss gt ability to produce heat)
• Plateau 3-5 hours core temp remains constant

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The Usual Suspects

• Balanced anesthesia
• Inhalation agents vasodilation, loss of
  thermoregulatory control, inhibits shivering
  reflex, reduces metabolism
• Muscle relaxants prevent shivering
• Barbituates peripheral vasodilation
• Regional inhibits cold sensation,
  vasodilation, proportional to block height
  tourniquets
• Narcotics vasodilation induce central
  hypothermia

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Whos at Risk?

• Extremes of age
• Body habitus
• Trauma, Burn victims
• Sex
• Length, type of procedure
• Low body wt, cachexia
• Pre-existing disorders endocrine, PVD
• Significant fluid shifts
• General / Regional Anesthesia

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Signs and Symptoms

• Compensatory Mechanisms - Depends on severity
  body
• attempts to balance
• Piloerection
• Shivering
• Tachypnea
• Increased HR, BP
• Increased CO, PVR
• Cold extremities

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Adverse Reactions

• Increased oxygen consumption
• Increased metabolic demand
• (400-500)
• Metabolic acidosis
• Decrease reflexes
• Dysfunction of coagulation cascade
• Untoward cardiac events increased mortality

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Theres more.

• Increased incidence of wound infection SCIP
  project - 2-10 (Sessler 2003)
• Prolonged medication metabolism
• Increased need for mechanical ventilation
• Longer PACU stays
• Patient discomfort / family satisfaction
• Higher patient costs reimbursement (2500-7000)
  (Mahoney, Odom 1999)

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Temperature Measurementcore vs near core

• Pulmonary artery
• Tympanic
• Temporal
• Oral
• Skin
• Axillary
• Rectal

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Which Device to Use?

• Accessibility of the measurement site
• Patient comfort and safety
• Practitioners ability to use device correctly
• Accuracy of the device
• Device consistency
• One temp does not a story tell

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Challenge

• Among most common surgical complication
• Evaluate risk
• Use of data available assessment, chart review,
  patient interview, scheduled surgery, planned
  anesthesia technique
• Be aware be prepared!

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ASPAN Clinical Guideline for the Prevention of
Unplanned Perioperative Hypothermia

• Need identification assessment / management
• 1998 Consensus conference multidisciplinary,
  multispecialty
• Recommendation - Develop Guideline / Test
• Pilot tested 6 institutions
• Published 2000-2001interventions not evidence
  based
• Revision underway (2009)

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5 Goals

• Establish a definition of normothermia
• Establish a definition of hypothermia
• Alert healthcare providers to the importance of
  maintaining perioperative hypothermia
• Provide guidelines for management
• Improve patient outcomes

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Management and Treatment

• Prevention of Unplanned Perioperative Hypothermia

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Phase Specific Recommendations
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Assessment - Preop

• Identify risk factors
• Assess patient temperature baseline
• Determine thermal comfort are you cold?
• Assess s/s of hypothermia (shivering,
  piloerection)
• Previous history

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Interventions - Preop

• Normothermic - institute preventive passive
  warming measures (warm blankets, head, foot
  covers, limit exposure)
• Active measures if temp lt36C (forced air, warmed
  fluids)
• Increase ambient room temperature
• Handoff to OR
• Expected outcome - 36C minimum

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Assessment Intraop

• Identify risk factors
• Thermal comfort prior to induction
• Assess for s/s of hypothermia 1st hour
• Follow ASA, AANA Standards of Practice

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Interventions - Intraop

• Follow AORN Guidelines ambient room temp
  (20-23C)
• Limit skin exposure, Monitor temperature
• Institute passive measures
• Active warming measure interventions forced air
  warming, room temp, warmed solutions, humidified
  oxygen, lights
• Expected outcomes normothermia maintained unless
  hypothermia desired

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Assessment Postop Phase I

• Identify risk factors
• Assess patients temp admit and q 30 minutes
• Determine thermal comfort
• Assess s/s of hypothermia

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Interventions Postop

• Normothermic preventative measures
• Temp may continue to drop, assess other s/s
• Assess patient comfort
• Temp lt36C active warming measures (forced warm
  air, warm fluids, irrigants, passive insulation)
• Increase ambient room temp (21-24C)
• Continue to monitor temp with VS, thermal comfort
• Medicate Demerol
• No hosing

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Expected Outcomes

• Patients minimum temp will be 36C prior to
  discharge from PACU
• Patient verbalizes acceptable comfort level
• S/S of hypothermia absent
• Handoff of treatment to next caregiver

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Phase II Assessment (PACU/ASU)

• Identify risk factors
• Temp on admission / discharge
• Ask patient about thermal comfort
• Observe for s/s
• Normothermic passive measures
• Hypothermic active measures

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Phase II Expected Outcomes

• Minimum temp 36C (or return to baseline) prior
  to discharge
• Patient has satisfactory thermal comfort level
• No s/s of hypothermia

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Phase II / Extended Care- Discharge

• Assess Temp risk factors pre/post
• Handoff to ICU / floor
• Instructions for dc home (monitor temp, limit
  exposure, warmed fluids)
• Follow up phone call expected outcomes

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http//www.nice.org.uk/nicemedia/pdf/CG65Guidance.
pdf
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Pearls of Wisdom

• Baseline temp
• Assessment is key
• Multidisciplinary / Multi-specialty approach
• Communicate with team
• Dont underestimate the effects of hypothermia

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References / Resources

• PeriAnesthesia Nursing Core Curriculum DeFazio
  Quinn, Schick, 2004.
• Ambulatory Surgical Nursing Core Curriculum,
  DeFazio Quinn, 1999.
• Recommended Practices for the Prevention of
  Unplanned Perioperative Hypothermia, AORN
  Journal, May 2007
• Warm Up to Your Patients, Hypothermia Management
  OR Nurse 2007
• ASPAN Competency Based Orientation, Chapter 11,
  Thermoregulation
• Perioperative Standards and Recommended
  Practices AORN 2008
• Proper Use of Patient Warming Devices Maintain
  normothermia without getting burned by heating
  mishaps Outpatient Surgery Magazine Dec 2006
• ASPAN 2006-2008 Standards Clinical Guideline for
  the Prevention of Unplanned Perioperative
  Hypothermia
• Postoperative hypothermia-The chilling
  consequences. AORN Journal May 2006
• Sessler DI Current concepts Mild
  interoperative hypothermia. N Eng J Med 336, 1997
• Kurz A, Marker E, Goll V, et al Interoperative
  hypothermia prolongs duration of postoperative
  recovery. Anesthesiology 87. 1997