Core-to-Big-Toe Temperature Gradient as a Marker of Peripheral Perfusion in Adult Patients With Septic Shock

NCT07871305 — Not yet recruiting, 54 participants, Assiut University

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Assessment of Core-to-Big-Toe Temperature Gradient (ΔT) as a Non-Invasive Marker of Peripheral Perfusion in Adult Patients With Septic Shock

Registry	NCT07871305
Status	Not yet recruiting
Study type	Observational
Enrollment	54 (Estimated)
Sponsor	Assiut University (Other)
Conditions	Septic Shock, Sepsis
Dates	start 2026-11-01 (estimated), primary completion 2027-11-01 (estimated), completion 2027-12-01 (estimated), first posted 2026-10-13, last updated 2026-10-13

-Summary

Septic shock is a life-threatening condition caused by severe infection that leads to dangerously low blood pressure and impaired blood flow to body tissues and organs. In the intensive care unit (ICU), restoring adequate tissue perfusion (blood flow) is essential during resuscitation. While doctors routinely monitor overall blood pressure, microcirculatory blood flow in peripheral tissues, such as the skin of the feet, can remain poor even after general blood pressure targets are reached. The difference between core body temperature and big-toe skin temperature (known as the core-to-big-toe temperature gradient, or ΔT) reflects blood vessel constriction in the extremities. When peripheral blood flow improves, skin temperature rises and this gradient narrows.

This prospective observational study aims to evaluate whether serial measurements of the core-to-big-toe temperature gradient significantly change during the first 12 hours of ICU resuscitation in adult patients presenting with septic shock. The study also examines whether changes in this gradient correlate with standard indicators of clinical recovery, including blood pressure, vasopressor medicine requirements, and blood lactate clearance.

All enrolled participants will receive standard, evidence-based medical care for septic shock in accordance with current international clinical guidelines; study participation will not interfere with, alter, or delay clinical treatment. Non-invasive measurements will be collected at three time points: at ICU admission (Hour 0), at 6 hours, and at 12 hours. These assessments include core body temperature, big-toe skin temperature measured with a calibrated infrared thermometer, finger capillary refill time, routine arterial blood pressure, and arterial blood lactate levels. If effective, this temperature gradient could provide clinicians with a simple, non-invasive, and cost-effective bedside indicator to monitor peripheral perfusion during critical care resuscitation.

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+Arms and interventions

Arm	Type	Interventions	Description
Adult Septic Shock Cohort			Adult intensive care unit (ICU) patients aged 18 years or older presenting with septic shock diagnosed according to Sepsis-3 criteria (suspected or documented infection, persistent hypotension requiring vasopressors to maintain MAP ≥ 65 mmHg, and serum lactate > 2 mmol/L despite initial intravenous fluid resuscitation of ≥ 30 mL/kg crystalloids within 3 hours). All patients receive standard-of-care resuscitation per institutional ICU protocols and international guidelines without experimental interventions. Serial observational measurements, including core temperature, big-toe skin temperature, core-to-big-toe temperature gradient (ΔT), capillary refill time (CRT), mean arterial pressure (MAP), serum lactate, and vasopressor dosage, are evaluated at ICU admission baseline (T0), 6 hours (T6), and 12 hours (T12).

+Outcome measures

Primary outcomes

Change in Core-to-Big-Toe Temperature Gradient (ΔT) From Baseline to 12 Hours [Baseline and Hour 12]: The core-to-big-toe temperature gradient (ΔT) is calculated as core temperature minus big-toe skin temperature (ΔT = Tcore - Ttoe), expressed in degrees Celsius (°C). Core temperature is measured via standard clinical ICU sensors (esophageal, urinary, or tympanic), and big-toe skin temperature is measured on the plantar surface of the big toe using a calibrated non-contact infrared thermometer (3 to 5 cm distance). Change is assessed as the value at Hour 12 minus the baseline value (Hour 0), where a reduction (negative change) reflects improved peripheral perfusion.

+Eligibility

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adult patients aged 18 years or older.
* ICU admission with a confirmed diagnosis of septic shock according to Sepsis-3 criteria (suspected or documented infection, persistent hypotension requiring vasopressors to maintain MAP ≥ 65 mmHg, and serum lactate > 2 mmol/L despite initial fluid resuscitation with at least 30 mL/kg of IV crystalloids within the first 3 hours).
* Enrollment during the initial resuscitation phase following ICU admission.
* Feasibility of obtaining serial temperature and hemodynamic measurements at the predefined study time points (baseline \[T0\], 6 hours \[T6\], and 12 hours \[T12\]).
* Written informed consent obtained from the patient or an authorized legal representative.

Exclusion Criteria:

* Pre-existing lower-limb peripheral vascular disease (PVD) or critical limb ischemia.
* Major lower-extremity trauma or amputation involving the measurement site.
* Deep vein thrombosis (DVT), active diabetic foot ulcer, severe peripheral edema, or occlusive dressing involving the big toe.
* Localized burns, infection, or severe skin pathology at the big-toe measurement site.
* Direct application of active thermal management devices to the lower limbs that may substantially affect temperature measurements.
* Severe underlying non-septic peripheral vascular or autonomic disorders expected to significantly affect peripheral temperature.
* Patients subjected to prolonged, non-standardized pre-ICU resuscitation exceeding 6 hours in the emergency department or hospital wards prior to ICU admission.
* Refusal or inability to obtain informed consent.

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