Mind the drain: expanding TIMING-ICP discussion

To the Editor,

We found the multicenter TIMING-ICP study by Mariani et al. [1] insightful, as it underscores time-related differences in severe brain injury management and the importance of efficient intracranial pressure (ICP) monitoring workflows. The study elegantly highlights practical time-dependent disparities in the management of severe brain injury and reinforces the need for streamlined workflows in ICP monitoring. While noninvasive multimodality strategies can reduce delays in neurological monitoring, invasive ICP monitoring remains essential in neurocritical care [2]. While we appreciate the authors’ efforts to reduce delays — a goal we strongly support — we respectfully believe some methodological concerns limit the study’s conclusions and clinical applicability.

The strength of the Timing-ICP study lies in demonstrating that initiating ICP monitoring earlier than current standard practice is feasible and potentially beneficial. However, the choice between monitoring modalities should be based on individual patient needs and the therapeutic capabilities required, not solely on procedural timing. In the study, intensivists treated predominantly severe TBI cases (82% vs. 49%), while neurosurgeons managed more SAH patients (27% vs. 11%). SAH patients typically require EVDs for hydrocephalus management and CSF blood clearance, while most severe TBI patients may be appropriately managed with parenchymal probes (bolts) alone. This indicates that device selection was based on clinical need rather than for study purposes, so comparing timing across different patient groups and situations is inappropriate.

Although the study utilizes an observational, non-randomized design, it is important to note that it evaluates inherently distinct procedures rather than different practitioners performing the same intervention. External ventricular drains (EVDs), when placed by neurosurgeons, fulfill both diagnostic and therapeutic roles by permitting cerebrospinal fluid (CSF) drainage for immediate ICP reduction. In contrast, bolts are limited to providing monitoring capabilities. While these probes are simpler to place, they do not facilitate CSF drainage—a critical component in the therapeutic management of intracranial hypertension.

EVDs enable precise ICP measurement and uniquely allow for dynamic regulation of ICP through CSF diversion, which is particularly beneficial for patients presenting with hydrocephalus, subarachnoid hemorrhage, or intraventricular hemorrhage [3]. On the other hand, measured intraparenchymal pressure can differ from ICP measured in the ventricles, with an average difference up to ± 6 mmHg [4]. Additional advantages of EVDs include their utility in CSF sampling for biomarker analysis [5] and the removal of intraventricular blood to enhance CSF flow [6]. EVDs are widely considered the gold standard for both diagnostic and therapeutic applications, especially in cases requiring long-term management of intracranial pressure [7].

The study inadvertently sheds light on a fundamental issue: patients requiring EVDs (for hydrocephalus, intraventricular hemorrhage, or therapeutic CSF drainage) may face longer delays, regardless of timing optimization efforts. Since EVD placement is inherently more complex than parenchymal probe insertion, higher complication rates in the neurosurgery group would be expected based on procedural differences alone. Therefore, comparing complication incidence between groups is also methodologically flawed and does not provide valid safety comparisons.

Standardizing procedures, patient profiles, therapeutic intensity, outcome measures, and employing randomized designs could clarify the feasibility of having intensivists implant ICP monitors.

No datasets were generated or analysed during the current study.

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Authors and Affiliations

1. Experimental Surgery Laboratory, Division of Neurological Surgery, University of São Paulo Medical School, Sao Paulo, Brazil

   Sergio Brasil, Samia Yasin Wayhs, Davi Jorge F. Solla & Raphael Bertani

2. University of São Paulo, Av. Eneas de Carvalho Aguiar 255, São Paulo, Brazil

   Sergio Brasil, Samia Yasin Wayhs, Davi Jorge F. Solla & Raphael Bertani

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1. Sergio BrasilView author publications

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2. Samia Yasin WayhsView author publications

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3. Davi Jorge F. SollaView author publications

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4. Raphael BertaniView author publications

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All authors equally contributed with paper writing and revision.

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Correspondence to Sergio Brasil.

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Brasil, S., Wayhs, S.Y., Solla, D. et al. Mind the drain: expanding TIMING-ICP discussion. Crit Care 29, 355 (2025). https://doi.org/10.1186/s13054-025-05607-0

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• Received: 01 August 2025

• Accepted: 05 August 2025

• Published: 14 August 2025

• DOI: https://doi.org/10.1186/s13054-025-05607-0

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