Head and Neck Cooling Decreases Tympanic and Skin Temperature, But Significantly Increases Blood Pressure

Abstract

Background and Purpose-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 35Ϯ13 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 highfrequency (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, PϽ0.05). Results-Forehead skin temperature dropped by 5.5Ϯ2.2°C with cooling onset and by 12.4Ϯ3.2°C after 20 minutes. Tympanic temperature decreased by 4.7Ϯ0.7°C within 40 minutes, and rectal temperature by only 0.3Ϯ0.3°C after 120 minutes. Systolic and diastolic BP increased immediately on cooling onset and rose by 15.3Ϯ20.8 mm Hg and 16.5Ϯ13.4 mm Hg (Pϭ0.004) 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. (Stroke. 2012;43:2142-2148.)

Induction of Cooling With a Passive Head and Neck Cooling Device

“…19 Consistent with the 2 recent trials, we found a large drop of in tympanic temperature starting immediately after external head cooling with the Sovika was applied reaching −1.69°C in mean after 1 hour of cooling. 12,13 Others reported a similar decrease of tympanic temperature using different passive head cooling devices. 20,21 Recording brain and tympanic temperature simultaneously, we clearly demonstrate that this drop is a local cooling effect overestimating, by far, the effect on brain temperature.…”

“…This may be attributable to selective brain cooling as concluded by Wang et al 10 or may be a delayed response of bladder temperature during rapid temperature changes when compared with other body core temperatures. 23 Regarding treatment effects on blood pressure Koehn et al 13 and Kallmünzer et al 12 reported conflicting data in healthy volunteers. Interestingly, Koehn et al 13 observed an immediate increase of blood pressure on cooling onset followed by a steady increase over a 2-hour time period, whereas the blood pressure increase in our study was also immediate, but transient (Figure 2).…”

“…23 Regarding treatment effects on blood pressure Koehn et al 13 and Kallmünzer et al 12 reported conflicting data in healthy volunteers. Interestingly, Koehn et al 13 observed an immediate increase of blood pressure on cooling onset followed by a steady increase over a 2-hour time period, whereas the blood pressure increase in our study was also immediate, but transient (Figure 2). Kallmünzer et al 12 did not observe any relevant blood pressure changes.…”

Effect of wearing an N95 respirator on infrared tympanic membrane temperature measurements

“…Temperature readings are routinely obtained on patients to screen for fever and, since 1986, the use of infrared thermometers for tympanic membrane temperature (TMT) measurements has become widespread in hospitals, clinics and medical practitioners’ offices because of their ease of use, rapid results, data storage capability, cleanliness, safety and assumed relationship to core body temperature [1, 2]. Prior research has shown that local alterations of facial, scalp and neck temperatures can impact TMT, presumably due to thermal effects on local dermal blood vessels that share circulation with vessels supplying the tympanic membrane [3–5]. Increased skin temperature, with concomitant warming of local dermal vessels in that area of the face covered by protective facemasks, results from a barrier effect upon local heat release mechanisms (i.e., facial skin heat convection, radiation and sweat evaporation) and from the trapping of warmed exhaled air in the mask deadspace [6–8].…”

Effect of temperature on FAD and NADH-derived signals and neurometabolic coupling in the mouse auditory and motor cortex

“…The biological factors that are sensitive to temperature in the whole animal, such as systemic or cerebral blood flow, blood pressure, and the affinity of oxygen to hemoglobin [53,109,4,72], were not present in the current preparation. As such, in the current study, it is not possible to account for the complex physiological environment of the brain and the network between brain and periphery.…”