title: Head and neck cooling decreases tympanic and skin temperature, but significantly increases blood pressure.
abstract: OBJECTIVE
  Localized head and neck cooling might be suited to induce therapeutic hypothermia in acute brain injury such as stroke. Safety issues of head and neck cooling are undetermined and may include cardiovascular autonomic side effects that were identified in this study.
  
  
  METHODS
  Ten healthy men (age 35±13 years) underwent 120 minutes of combined head and neck cooling (Sovika, HVM Medical). Before and after onset of cooling, after 60 and 120 minutes, we determined rectal, tympanic, and forehead skin temperatures, RR intervals, systolic and diastolic blood pressures (BP), laser-Doppler skin blood flow at the index finger and cheek, and spectral powers of mainly sympathetic low-frequency (0.04-0.15 Hz) and parasympathetic high-frequency (0.15-0.5 Hz) RR interval oscillations and sympathetic low-frequency oscillations of BP. We compared values before and during cooling using analysis of variance with post hoc analysis; (significance, P<0.05).
  
  
  RESULTS
  Forehead skin temperature dropped by 5.5±2.2°C with cooling onset and by 12.4±3.2°C after 20 minutes. Tympanic temperature decreased by 4.7±0.7°C within 40 minutes, and rectal temperature by only 0.3±0.3°C after 120 minutes. Systolic and diastolic BP increased immediately on cooling onset and rose by 15.3±20.8 mm Hg and 16.5±13.4 mm Hg (P=0.004) after 120 minutes, whereas skin blood flow fell significantly during cooling. RR intervals and parasympathetic RR interval high-frequency powers increased with cooling onset and were significantly higher after 60 and 120 minutes than they were before cooling.
  
  
  CONCLUSIONS
  Head and neck cooling prominently reduced tympanic temperature and thus might also induce intracerebral hypothermia; however, it did not significantly lower body core temperature. Profound skin temperature decrease induced sympathetically mediated peripheral vasoconstriction and prominent BP increases that are not offset by simultaneous parasympathetic heart rate slowing. Prominent peripheral vasoconstriction and BP increase must be considered as possibly harmful during head and neck cooling.
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Koehn
authors.forename: Rainer
authors.initials: R
authors.lastname: Kollmar
authors.forename: Camelia-Lucia
authors.initials: CL
authors.lastname: Cimpianu
authors.forename: Bernd
authors.initials: B
authors.lastname: Kallmünzer
authors.forename: Sebastian
authors.initials: S
authors.lastname: Moeller
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwab
authors.forename: Max J
authors.initials: MJ
authors.lastname: Hilz
mesh_terms: D000368:Aged; D001341:Autonomic Nervous System / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D004562:Electrocardiography; D005385:Fingers / Q000098:blood supply; D006257:Head; D006339:Heart Rate / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects* / Q000379:methods*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009333:Neck; D012039:Regional Blood Flow; D015656:Respiratory Mechanics / Q000502:physiology; D012867:Skin / Q000098:blood supply; D012879:Skin Physiological Phenomena; D012881:Skin Temperature; D020521:Stroke / Q000628:therapy*; D016683:Supine Position; D014432:Tympanic Membrane / Q000502:physiology*