Need to Define Time and Goals while Planning “External Ventricular Drain”

INTRODUCTION

The external ventricular drain (EVD) has been a cornerstone of neurocritical care for decades. It is a temporary device placed into the lateral ventricles of the brain to allow external cerebrospinal fluid (CSF) drainage and/or monitoring of intracranial pressure (ICP).¹ Despite its widespread use, the terminology surrounding EVDs rarely reflects their specific clinical intent. An EVD may serve diverse roles: Continuous CSF drainage in subarachnoid hemorrhage, intermittent drainage to control elevated ICP, or exclusive ICP monitoring tool in traumatic brain injury (TBI). Despite these critical roles, the term “EVD” fails to convey these distinctions, thereby under-representing the device’s full therapeutic and diagnostic value.

ONE DEVICE, MANY ROLES

Accurate and complete information during intensive care unit rounds is essential for the safe management of EVDs. Patient handover involves the systematic transfer of clinical information, professional responsibility, and accountability between individuals and teams involved in patient care.² Ineffective communication during handover is a well-recognized cause of medical error and poses a significant risk to patient safety.³ Failure to explicitly define the goal of an EVD can lead to mismanagement, with potentially catastrophic consequences. Ambiguity commonly results in inconsistencies between nursing staff, neurosurgeons, and intensivists regarding whether the drain should be opened or clamped. This is further compounded by documentation lapses, where ambiguous charting of EVD goals or status or goals leads to confusion during handovers.

An EVD serves a dual purpose, enabling both ICP monitoring and CSF drainage. The ability to drain CSF enables tight control of ICP and optimization of cerebral perfusion pressure.⁴ The stopcock position determines whether ICP is transduced for monitoring or CSF is diverted into the collection bag.⁵ Without explicit clarification, these functions may be inadvertently interchanged by multidisciplinary teams, resulting in contrary interventions or missed therapeutic windows.

Once an EVD is placed, additional management goals include optimization of cerebral physiology, minimization of complications, and determination of readiness for weaning or removal.⁶ These objectives further underscore the importance of clearly defining and communicating the intended purpose of the device at the time of insertion.

SHIFTING TOWARD GOAL-ORIENTED TERMINOLOGY

We recommend discontinuing the unqualified use of the term “EVD” and adopting goal-specific descriptive words preceding the term such as:

• “ICP-monitoring-only EVD”

• “Therapeutic CSF diversion EVD”

• “Mixed-use EVD with scheduled drainage.”

During clinical handovers and in written documentation, these labels should be accompanied by a concise report including:¹

• Indication of EVD placement

• ICP trends, including qualitative evaluation of ICP waveform components

• Any data available from EVD clamp trials

• P1:P2 ratio evaluation to assess ICP compliance curve

• Data from EVD clamp trials, particularly during patient transport

Since ICP values fluctuate over time, the context of reported values must be clearly communicated. It should be specified whether the reported ICP represents a single time point, a mean value, or a range over a defined period. In a study analyzing simultaneous video recordings and continuous ICP monitoring during 15-min EVD clamp trials, the probability that a single ICP measurement reflected the entire observation period was found to be very low.⁴ The indication for EVD placement is pivotal, as it dictates the drainage strategy. Clinical management decision commonly involves choosing between continuous drainage with intermittent ICP monitoring (open EVD) and continuous ICP monitoring with intermittent CSF drainage (monitor EVD).⁷ Continuous drainage may impair the EVD’s ability to detect ICP trends.⁸ In adult patients with severe TBI, continuous drainage (open EVD) has been associated with improved ICP control,⁹ whereas in aneurysmal subarachnoid hemorrhage, open EVD management is associated with a higher complication rate.¹⁰

CONCLUSION

The term “EVD” is not sufficient as a standalone descriptor in modern neurocritical care. There is an urgent need to specify the intended purpose, time frame, and management strategy for each EVD placed. Adopting goal-directed terminology can ensure clearer communication, reduce errors, and result in improved patient outcomes. It is time to replace imprecise abbreviations with accurate, purpose-directed terminology.