Table 2 Studies associated with HVAC use

Price et al. 2003, [37],

“Cooling strategies for patients with severe cerebral insult in ICU”

Clinical trial

Analysis of the efficacy of different cooling strategies for patients with cerebral insult and elevated body temperature

• (I) -Group a) paracetamol and depending on the clinical course: Continuation of paracetamol and additional “fanning” [portable rotary fans were preferably used]

-Group b) no paracetamol and depending on the clinical course: Continuation with no intervention or additional “fanning”

• (C) -Group a) paracetamol and depending on the clinical course: Continuation of paracetamol alone or paracetamol and additional other cooling methods (e.g. ice packs)

• -Group b) no paracetamol and depending on the clinical course: Continuation with no intervention or use of other cooling methods (e.g. ice packs)

• (S) Intensive care unit

• (D) Criteria to end the procedure were not stated; it is referred to temperature measurements over 24 h

• N total = 67

Intervention:

-Group a) paracetamol and fanning:

n = 12

-Group b) no paracetamol and fanning:

n = 16

Control:

-Group a) paracetamol and another cooling strategy:

n = 25

-Group b) no paracetamol and another cooling strategy:

n = 14

• Physical cooling strategies (fanning) do not add to body cooling regardless of paracetamol use

• Use of fan is negatively associated with a reduction in body temperature

• Report of hygiene problems associated with fan use

• Uneven patient allocation to different cooling methods

• “Fanning” could not be specified

Ferguson & Martin 1991, [38],

“A study of skin temperatures, sweat rate and heat loss for burned patients”

Clinical trial

Analysis of the influence of the thermal environment on heat loss/ evaporation of patients with severe burns

- Intensive care unit: Measurement of skin temperature of volunteers; measurement of wound temperatures, evaporation from burn wounds and sweating rates of burned patients

- General ward: Measurement of sweating rates of patients

• (I) - Intensive care unit: Clean air unit: Small box with ultra-flow clean air system with uniform heated airflow (cf. 41)

(28 °C – 38 °C);

- General ward: Additional heating

• (C) Not fully applicable

• (S) Intensive care unit, general ward

• (D) Few days/until wounds dried off

Intervention 1 (intensive care unit):

n = 12, volunteers:

n = 6

Intervention 2 (general ward), temperature not specified:

n = 7

• During the first 3 days wound temperature was cooler than intact skin; after that time wound temperature was higher

• Evaporation rate from wounds varied between 100 and 700g/m²/h

• With a higher percentage of burned surface, room temperature could be higher without initiating sweating

• Radiation and convection loss is lower in ICU (higher temperature). Losses from burn wounds were lower in the first few days (lower wound temperature). Overall convective losses: Similar in ICU and general ward.

• Difficult to identify participants in intervention groups

• Healthy volunteers were enrolled

• Clean air unit shows features of air conditioning but reported maximum room temperatures are outside the thermal comfort range

Johnston et al. 2006, [39],

“Body temperature management after severe traumatic brain injury: methods and protocols used in the United Kingdom and Ireland”

Cross-sectional

Survey on “methods and protocols used in the management of body temperature in patients with severe TBI“

• (I) Convection fan and other methods

• (C) Not fully applicable

• (S) Intensive care unit

• (D) Up to 48 h

• 33 centres

• Besides fans, a variety of methods is used for temperature management

• Only 2 out of 33 intensive care units have a convection fan implemented as the first-line method

• If the first-line method failed to lower body temperature, mostly a combination of direct body cooling methods was used

• Fan use was mentioned as an adjunct to first-line treatment

• The survey was conducted with intensive care nurses

• “Convection fan” could not be specified

De Vries & Feix 2018, [40],

“Fever burden, septic screening, and cooling therapies in brain injury patients on a regional neurosciences intensive care unit”

Cross-sectional

Analysis of fever incidence and adherence to fever management protocols in the intensive care unit

• (I) “Cold air humidification”, “fan” and other physical and medical cooling methods

• (C) Not applicable

• (S) Intensive care unit

• (D) Not specified

• N = 38

• Temperature burden in febrile patients was high

• Besides screening for fever causes, 9 patients were treated with paracetamol alone, 9 patients had two or more cooling methods, 5 febrile patients were not treated

• Outcomes according to different methods are not reported

• The analysis deals with adherence to fever treatment protocols

• Most patients (n = 29) had a subarachnoid haemorrhage

• Interventions are part of a bundle of cooling strategies including medical treatment (e.g. paracetamol)

• Frequencies for use of “cold air humidification” or “fan” are not specified

• “Fan” could not be specified