Table 2.

Individual patient serum sodium and intracranial pressure correlations

Patient group	Patients in each R2 quartile
	< 0.25	0.26 to 0.5	0.51 to 0.75	> 0.75
All patients	63 (81%)	9 (11%)	6 (8%)	0 (0%)
Those with craniotomy/craniectomy	33 (77%)	6 (14%)	4 (9%)	0 (0%)
Those with ventriculostomy	28 (90%)	2 (7%)	1 (3%)	0 (0%)
Those with continuous infusion hypertonic saline	10 (100%)	0 (0%)	0 (0%)	0 (0%)
Those without ventriculostomy, craniotomy/craniectomy, or continuous infusion hypertonic saline	19 (90%)	2 (10%)	0 (0%)	0 (0%)

Data presented as n (%). Each serum sodium measurement was matched to the corresponding intracranial pressure to calculate individual R² values for every patient. Patients were divided into different groups based on whether or not they received various treatments and/or procedures during the study period (for example, craniectomy, ventriculostomy, continuous infusion hypertonic saline). The number of patients per group falling into each R² quartile is provided.