Physiological Changes in Adult Intensive Care Patients Following Contact With Their Primary Caregiver

This study is a randomized, controlled, parallel-group, double-blind clinical trial designed to evaluate the effect of therapeutic contact provided by the primary caregiver on physiological parameters in adult intensive care unit (ICU) patients. Participants will be randomly assigned in a 1:1 ratio to either the intervention group (therapeutic contact) or the control group (no therapeutic contact) using block randomization generated by an independent external advisor. Allocation concealment will be ensured through the use of sequentially numbered, opaque, sealed, tamper-evident envelopes.

Sample size was calculated for the comparison of means between two independent groups using a 95% confidence level (α = 0.05), 80% statistical power (β = 0.20), a standard deviation of 7.6, and a minimum clinically meaningful difference of 5 units. The estimated sample size was 36 participants per group. After adjustment for an anticipated 10% attrition rate, a total of 80 participants (40 per group) will be enrolled.

Physiological outcomes include heart rate, systolic blood pressure, diastolic blood pressure, respiratory rate, oxygen saturation, and body temperature. Measurements will be obtained using a bedside multiparameter monitor and recorded on a standardized physiological data collection form. Equipment calibration will be verified before each measurement. Outcomes will be assessed 10 minutes before the caregiver visit, 10 minutes after the start of the visit, and 10 minutes after completion of the visit.

Changes in physiological outcomes will be calculated as the difference between baseline measurements and subsequent assessments. Data analysis will be performed using IBM SPSS Statistics Version 29.0 (IBM Corp., Armonk, NY, USA). Continuous variables will be summarized using means and standard deviations or medians and interquartile ranges, according to data distribution. Categorical variables will be summarized using frequencies and percentages. Normality will be evaluated using the Kolmogorov-Smirnov test. For each physiological outcome, change scores will be calculated by subtracting baseline values from measurements obtained during and after the caregiver visit. Mean changes between the intervention and control groups will be compared using the independent-samples t-test or the Mann-Whitney U test, as appropriate. Effect sizes will be estimated using Cohen's d. Statistical significance will be established at p < 0.05. The study was approved by the Research Ethics Committee of the Instituto Nacional de Enfermedades Respiratorias "Ismael Cosío Villegas". The trial will be conducted in accordance with the Declaration of Helsinki and applicable Mexican regulations governing health research. Written informed consent will be obtained from all participants or their legally authorized representatives before enrollment. Adverse events will be documented and reported to the institutional ethics committee and ClinicalTrials.gov according to applicable regulatory requirements.

Inclusion criteria

Patient Criteria:

• Adults aged 18 years or older.
• Admission to the intensive care unit (ICU) for 24 to 48 hours.
• Richmond Agitation-Sedation Scale (RASS) score between -3 and -1 or between 0 and +3.
• Glasgow Coma Scale score greater than 13.

Primary Caregiver Criteria:

• Identified as the patient's primary caregiver.
• Willing and able to participate in the study.
• Provides written informed consent prior to study participation.

Exclusion criteria

Patient Criteria:

• Diagnosis of a neurological disorder (e.g., cerebrovascular disease or stroke).
• Multiple organ dysfunction syndrome (MODS).
• Unstable or difficult-to-control cardiac arrhythmias.
• Fever (body temperature ≥ 37.5°C) at the time of assessment.
• Hypertension (blood pressure ≥ 130/80 mmHg) at the time of assessment.

Primary Caregiver Criteria:

• Unable to be present to perform the intervention according to the study protocol.