Evaluation of pain severity in critically ill patients on mechanical ventilation.

Objectives: To elucidate how patients' illness severity, respiratory status, or haemodynamics are associated with the pain score of critically ill patients.

Methods: This was an observational study of patients on mechanical ventilation after surgeries. At rest and on turning, patient pain was evaluated using the Behavioural Pain Scale (BPS) and the Critical-Care Pain Observation Tool (CPOT). Related factors were collected from medical records and analysed.

Findings: Multiple logistic regression analysis was performed using data on 127 scenarios. An increase of >2 in BPS score on turning was affected by the Acute Physiology and Chronic Health Evaluation (APACHE) II score (odds ratio [OR] = 0.864), systolic blood pressure at rest (OR = 1.032), BPS at rest (OR = 0.638), heart rate difference (OR = 1.124), and tidal volume difference (OR = 0.548). An increase of >2 in CPOT on turning score was associated with the APACHE II score (OR = 0.894), Sequential Organ Failure Assessment score (OR = 1.248), systolic blood pressure at rest (OR = 1.025), heart rate difference (OR = 1.096), and tidal volume difference (OR = 0.578).

Conclusion: The Behavioural Pain Scale and the Critical-Care Pain Observation Tools were associated with illness severity and haemodynamics. A reduction in tidal volume may be useful in assessing pain.