Thermogard XP for therapeutic hypothermia after cardiac arrest

Search strategy

The search strategy was designed to identify evidence on the clinical and cost effectiveness of Thermogard for therapeutic cooling in post‑cardiac arrest.

The strategy was developed for MEDLINE (Ovid interface). The strategy was devised using a combination of subject indexing terms and free text search terms in the title, abstract and keyword heading word fields. The search terms were identified through discussion within the research team, scanning background literature, browsing database thesauri and use of the PubMed PubReMiner tool. The strategy reflected the nature of the MIB assessments as rapid evidence reviews.

The main structure of the search strategy comprised 3 concepts:

The search concepts were combined as follows: Induced hypothermia AND key device characteristic AND cardiac arrest.

Additional search lines included a search on manufacturer terms, a search on device brand name terms, and highly focused searches on invasive cooling, non‑specific cooling systems and devices described as 'temperature modulation' therapies. These additional lines were designed to capture any records that may have been missed by the main 3‑concept approach.

The strategy excluded non‑English language publications. Animal studies were also excluded using a standard algorithm. No additional filters for study design were applied. Results were limited to studies published from 2000. This date reflected the year in which the device first became commercially available.

The final MEDLINE strategy was peer‑reviewed by an independent information specialist. The MEDLINE strategy was translated appropriately for the other databases searched. The PubMed search was limited to records which were not fully indexed on MEDLINE. Conference‑related records were excluded from the Embase search.

The following databases were searched:

Evidence selection

A total of 997 records were retrieved from the literature search. After de‑duplication, 594 records remained and were sifted against the inclusion criteria at title and abstract level.

Records were sifted independently by 2 researchers. Any disagreements were discussed and agreement was reached in all cases, so a third independent arbiter was not required. The first sift removed 541 records based on the following exclusion criteria:

Full articles were retrieved for the 53 remaining studies and a full text assessment was done independently by 2 researchers to identify relevant primary research addressing the key cooling efficiency outcomes of interest. One study explicitly investigated Thermogard XP and 2 additional studies explicitly stated that the intervention was the immediate predecessor CoolGard 3000 system. These 3 studies were included for full review.

A further 7 studies reporting relevant outcomes of interest stated that the intervention was the CoolGard system, but it could not be absolutely determined whether evidence from these 7 studies included cases using the earlier CoolGard 2050 system as the intervention.