From the Guidelines
Permissive hypertension protocol involves intentionally maintaining blood pressure at higher than normal levels, typically ranging from 160-180/90-105 mmHg, in specific clinical scenarios such as large vessel occlusive stroke, severe intracranial stenosis, or in the immediate post-thrombectomy period. This approach is based on the physiological principle that elevated blood pressure helps maintain cerebral perfusion pressure in areas with compromised blood flow, potentially preserving the ischemic penumbra 1. The protocol should be maintained for 24-72 hours after stroke onset or intervention, with gradual transition to normal blood pressure goals thereafter. Implementation involves withholding antihypertensive medications unless blood pressure exceeds the upper threshold, using short-acting agents like labetalol (10-20 mg IV), nicardipine (5-15 mg/hr IV), or clevidipine (1-2 mg/hr IV) when intervention is needed.
Some key points to consider when implementing the permissive hypertension protocol include:
- Withholding antihypertensive medications unless blood pressure exceeds the upper threshold
- Using short-acting agents like labetalol, nicardipine, or clevidipine when intervention is needed
- Maintaining the protocol for 24-72 hours after stroke onset or intervention
- Gradually transitioning to normal blood pressure goals thereafter
- Regular neurological assessments to monitor for clinical deterioration
- Individualizing the approach based on specific patient factors such as stroke etiology, location, and comorbidities.
It's worth noting that the 2007 guidelines for the management of arterial hypertension recommend lowering blood pressure to at least below 140/90 mmHg in all hypertensive patients, and pursuing lower values if tolerated 1. However, in the context of permissive hypertension, the goal is to maintain higher blood pressure levels to ensure adequate cerebral perfusion. The most recent and highest quality study, published in 2020, provides guidance on the diagnosis and management of hypertension in the primary care setting, but does not specifically address the permissive hypertension protocol 1.
From the Research
Permissive Hypertension (HTN) Protocol
There is limited information available on the permissive Hypertension (HTN) protocol in the provided studies. However, some studies discuss blood pressure goals in critically ill patients, which may be relevant to the permissive HTN protocol.
- The concept of permissive hypertension is not explicitly mentioned in the studies, but some studies discuss the importance of individualizing blood pressure targets in critically ill patients 2, 3.
- A study published in 2022 found that targeting a higher mean arterial pressure (MAP) goal of > 70 mm Hg was associated with similar risks of mortality, duration of mechanical ventilation, and ICU length of stay compared to a standard MAP goal of 60 - 70 mm Hg 4.
- Another study published in 2015 suggested that targeting an MAP of 65-70 mmHg in patients with septic shock who do not have chronic hypertension is a reasonable first approximation, while targeting a higher MAP of 80-85 mmHg in patients with chronic hypertension may minimize renal injury but increases the risk of arrhythmias 2.
- A review published in 2023 emphasized the importance of individualizing blood pressure targets in the ICU, taking into account specific cardiac pathophysiology and patient characteristics, and using both invasive and noninvasive monitoring modalities to ensure adequate blood pressure and end-organ perfusion 3.
Blood Pressure Targets
The studies suggest that blood pressure targets should be individualized based on patient characteristics and underlying conditions. Some general guidelines for blood pressure targets include:
- Targeting an MAP of 65-70 mmHg in patients with septic shock who do not have chronic hypertension 2.
- Targeting a higher MAP of 80-85 mmHg in patients with chronic hypertension to minimize renal injury, but with increased risk of arrhythmias 2.
- Maintaining adequate blood pressure within a certain range to support cardiac function and ensure end-organ perfusion in the cardiac ICU 3.