SYSTEM, THERMAL REGULATING 74-DWJ

K960167 · Augustine Medical, Inc. · DWJ · Jun 17, 1996 · Cardiovascular

Device Facts

• Record ID: K960167
• Device Name: SYSTEM, THERMAL REGULATING 74-DWJ
• Applicant: Augustine Medical, Inc.
• Product Code: DWJ · Cardiovascular
• Decision Date: Jun 17, 1996
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 870.5900
• Device Class: Class 2
• Attributes: Therapeutic

Device Story

Bair Hugger Model 505 Warming Unit is a convective patient warming system. Device draws air, filters it through a 0.2-micron filter, heats it, and delivers it via a hose to an inflatable blanket placed over the patient. Used in clinical settings, including operating rooms, to maintain normothermia. Operated by healthcare professionals. Safety features include independent mechanical thermostats for over-temperature detection, triggering audible/visual alarms and automatic heating element shutdown. Blankets include tape barriers to prevent air migration toward surgical sites. Output is warm air; clinical benefit is prevention of hypothermia. Effectiveness is established by comparing air temperature specifications to the predicate Model 500 unit.

Clinical Evidence

Bench testing only. Performance data demonstrates air temperature delivery within specified ranges. Literature cited (Hall 1991, Zink 1992/1993) indicates that the 500 Series units do not increase the incidence of microbial or wound contamination in the operating room.

Technological Characteristics

Convective warming system; 0.2-micron air filtration; mechanical thermostat-based over-temperature detection system; audible and visual alarm indicators; heating elements; hose and inflatable blanket interface. No software or digital components described.

Indications for Use

Indicated for patient warming therapy. Contraindicated for use on lower extremities during aortic cross-clamping due to risk of thermal injury to ischemic limbs. Patients with poor perfusion require monitoring during prolonged warming sessions.

Regulatory Classification

Identification

A thermal regulating system is an external system consisting of a device that is placed in contact with the patient and a temperature controller for the device. The system is used to regulate patient temperature.

Predicate Devices

• Bair Hugger Patient Warming System, Model 500 Warming Unit

Submission Summary (Full Text)

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JUN 17 1996
k960167
January 10, 1996

# 510(k) Summary of Safety & Effectiveness

## SAFETY

This 510(k) Summary of Safety & Effectiveness information is being submitted in accordance with the requirements of SMDA 1990 and 21 CFR 807.92. The device is a Class II device, System Thermal Regulating 74 DWG, Patient Warming System called the Bair Hugger® Total Temperature Management® System - Model 505 Warming Unit. The predicate device is the Bair Hugger® Patient Warming System, Model 500 Warming Unit. The following summarizes safety issues related to skin surface warming devices and the measures to prevent these problems.

## 1. Summary of Safety:

### A. Injuries to tissue:

Cutaneous burns. Thermal injury is determined by a combination of temperature and time. Patients with ischemic limbs or extremely poor perfusion are especially susceptible to thermal injuries.

**Prevention:** The Bair Hugger® Series 500's Maximum Heat Output (setting III at 43°C) does not provide temperatures high enough to cause burns to tissue when used as directed. Performance testing demonstrated that by the time the air leaves the Bair Hugger Temperature Management Units, flows through the hose and is circulated through the inflatable Blanket placed over the patient, temperatures have dropped from 43°C to 41°C. These temperatures are well within the range of safety¹,².

**Over-temperature condition:** Bair Hugger Temperature Management Units temperature-out-of-range detection system is an independent, mechanical, using thermostats to detect over temperature conditions. The system triggers audible and visual alarms and shuts the heating elements down when over-temperature conditions are detected.

**Labeling:** Labels affixed to each Bair Hugger Blanket at the inlet port and packaged with each Bair Hugger Blanket read as follows:

"Contraindications: 1. Do not apply heat to lower extremities during aortic cross-clamping. Thermal injury to ischemic limbs may occur.

2. Do not leave patients with poor perfusion unmonitored during prolonged warming therapy sessions."

### B. Hyperthermia:

Warming treatment continued past the point of the patient reaching normothermia may eventually produce hyperthermia³.

**Prevention:** Instructions packaged with each Bair Hugger® Blanket instruct the user to "Monitor the patient's temperature at least every 10-20 minutes."

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C. Other Safety Concerns:

1. Contamination. Airborne contamination from air blown intraoperatively across the surgical wound may result in airborne contamination.

**Prevention of airborne contamination:** All Bair Hugger® Blankets designed for use in the operating room feature a tape barrier which prevent air from migrating toward the surgical site. Additionally, air is filtered through a 0.2 micron filter. Two studies have concluded that the Bair Hugger® 500 Series Units (that have the same air output specifications and the same filter density as the Model 505) do not increase the incidence of microbial or wound contamination⁴,⁵.

2. Summary of Effectiveness. Performance data show that the Model 505 Patient Warming System delivers air temperatures in the warming mode within the same specifications as the Bair Hugger® Model 500 Patient Warming System, using the same Bair Hugger® Blankets.

Bibliography on which the above summary is based:

1. Moritz AR, Henriques FC. The Relative Importance of the Time and Surface Temperature in the Causation of Cutaneous Burns. Am J Path 23:695-720, 1947.
2. Stoll AM, Green LC. Relationship Between Pain and Tissue Damage Due to Thermal Radiation. J Apply Phys 14:373-382, 1959.
3. Genauer, MB. Postoperative Heat Stroke. Anesthesiology 7:302-309, 1946.
4. Hall, A. Bair Hugger® Warmer Does Not Increase Microbial Contamination in the Operating Room. Abstract presented at the Post Graduate Assembly, New York Society of Anesthesiologists, New York, NY, December 1991.
5. Zink, RS. Convective Warming Therapy Does Not Increase the Risk of Wound Contamination in the Operating Room. Anesthesiology 77:A1093, 1992 & Anesth Analg, 1993:76;50-3.

CONTACT PERSON: Scott D. Augustine

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