Children in the experimental group received a therapeutic video game intervention in addition to the pre-treatment routine.

Children in the control group underwent routine clinical practice. No other intervention was performed.

Half an hour before the first treatment in the morning, the screens around the patients' beds were closed by the researcher. The child was asked to choose one of the introduced games and the game he/she chose from the tablet was turned on. Children were asked to wear headphones for sound isolation and the sound was adjusted at the appropriate decibel setting. Half an hour before the treatment, children were allowed to play the video game until the treatment without any different warning. Physiologic Parameter Assessment Form, Child Anxiety and Fear Scale, Child Pain Scale were filled by the researcher 1 minute before and 1 minute after the procedure. Finally, Parental Satisfaction Scale was completed at the end of the intervention.

A descriptive characteristics information form for parents and children was prepared by the researchers in line with the literature and the data of both the experimental and control groups were collected before the intervention.

The descriptive characteristics form was based on a literature review by the investigator. Heart rate (min), oxygen saturation (SpO2%), blood pressure (mmHg) and respiratory rate (min) were measured 1 minute before treatment administration.

Children's State Anxiety and Children's Fear Scale was developed by McMurtry et al. in 2011. The scale was designed to measure the fear levels of children aged 4-10 years. The scale was translated into Turkish by Gerçeker et al. in 2018 and the validity-reliability coefficient was found to be 0.89. The scale score is formed by scoring five drawn facial expressions (0=no fear to 4=severe fear) shown visually to the child. Anxiety and fear scores of the child were scored one minute before the treatment.

Visual Analog Scale (VAS) was developed by Wong and Baker in 1988. Patients' pain levels are evaluated by scoring with facial expressions. It is used in children who have the ability to communicate and are conscious. The scale has 6 faces that are scored between 0 and 5. In scoring, the child chooses the face that best expresses him/her and "0" indicates no pain, "1" indicates a little pain, "2" indicates a little more pain, "3" indicates more pain, "4" indicates quite a lot of pain and "5" indicates the most severe pain level. One minute before the treatment, the child's pain is scored by VAS.

Heart rate (min), oxygen saturation (SpO2%), blood pressure (mmHg) and respiratory rate (min) were measured one minute after treatment administration.