Teamwork impacts staff wellbeing and patient outcomes. This study focuses on the factors that facilitate or challenge teamworking practices in ICUs. A rapid ethnographic approach, including observation and interviews, ensures that what people say they do and what they actually do match up in practice. This project has two interrelated components: observation and one-on-one interviews.

Observations: A researcher will shadow various healthcare professionals in 10 different ICU units. These observations will cover multiple professions and different shift patterns, including handovers, ward rounds, and multi-disciplinary team meetings. This allows for a range of interactions to be covered which will elucidate how healthcare professionals work together. Written consent will be obtained from each healthcare professional shadowed, and researchers will observe in 20-minute blocks where possible to minimize burden. Researchers will record their observations in the form of fieldnotes which will be either hand-written or recorded on a dedicated iPad. Fieldnotes will later be expanded on, typed up, and pseudonymized. During this observation period, researchers may engage in informal discussions with healthcare professionals to clarify what they observe where appropriate though these will not be audio recorded. Additionally, while patients and their family members will provide verbal consent where possible for the researcher to be present in the room or at the bedside, data will not be collected on them.

All three members of the research team will visit each site; however, one researcher will remain at the site for the duration of the research period. Each site will incur a minimum of 75 observation hours over the course of four weeks.

Interviews: To supplement the observations, researchers will conduct one-on-one semi-structured interviews with key healthcare professionals in each study site. Initially, these individuals will be identified and approached by the researcher during the observation phase. Researchers will then employ a snowball method to identify further potential healthcare professionals to include. At least 15 healthcare professionals per site will be interviewed for this study. All healthcare professionals will provide their written consent for the interview.

Data analysis: All formal interview audio recordings will be recorded using a Dictaphone voice recorder with the participant's consent. These recordings will be transcribed using a King's College London approved transcription service and anonymised. Thematic analysis will be conducted to identify recurring themes (Braun and Clarke, 2006). The transcripts will be read and reread for familiarization before coding the data. During the coding process, a code book will be created with a list of codes and descriptions to accompany. To validate the coding, each researcher will code a small, random selection of the transcripts using the code book. Coding will be discussed to reach an agreement. Field notes obtained through observation will be spoken aloud by the researcher using a Dictaphone voice recorder and sent to the transcription service. The transcripts will be anonymized and uploaded to NVivo to be thematically analysed. The analysis will focus on answering the research questions, using constructs from the conceptual frameworks to sensitize the analysis.