Unusual Source of Air Leak in a Pediatric Anesthesia Breathing Circuit

Abstract Mechanical respirators typically use a plastic circuit apparatus to pass gases from the ventilator to the patient. Structural integrity of these circuits is crucial for maintaining oxygenation. Anesthesiologists, respiratory therapists, and other critical care professionals rely on the circuit to be free of defects. The American Society for Testing and Materials maintains standards of medical devices and had a standard (titled Standard Specification for Anesthesia Breathing Tubes) that included circuits. This standard, which was last updated in 2008, has since been withdrawn. Lack of a defined standard can invite quality fade—the phenomenon whereby manufacturers deliberately but surreptitiously reduce material quality to widen profit margins. With plastics, this is often in the form of thinner material. A minimum thickness delineated in the breathing circuit standard would help ensure product quality, maintain tolerance to mechanical insults, and avert leaks. Our impression is that over the recent years, the plastic in many of the commercially available breathing circuits has gotten thinner. We experienced a circuit leak in the middle of a laminectomy due to compromised plastic tubing in a location that evaded the safety circuit leak check that is performed prior to surgery. This compromised ventilation and oxygenation in the middle of a surgery in which the patient is positioned prone and hence with a minimally accessible airway; it could have resulted in anoxic brain injury or death. The incident led us to reflect on the degree of thinness of the circuit's plastic.

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Effects of a Heated Anesthesia Breathing Circuit on Body Temperature in Anesthetized Rhesus Macaques (Macaca mulatta)

Journal of the American Association for Laboratory Animal Science ◽

10.30802/aalas-jaalas-21-000058 ◽

2021 ◽

Author(s):

Philip A Bowling ◽

Michael A Bencivenga ◽

Mary E Leyva ◽

Briittnee E Grego ◽

Robin N Cornelius ◽

...

Keyword(s):

Body Temperature ◽

Rhesus Macaques ◽

Breathing Circuit ◽

Body Temperatures ◽

Intraoperative Complication ◽

Forced Air Warming ◽

Initial Drop ◽

Anesthesia Breathing ◽

Forced Air ◽

Warming Devices

This study evaluated the effects of using a heated anesthesia breathing circuit in addition to forced-air warming on bodytemperature in anesthetized rhesus macaques as compared with forced-air warming alone. Hypothermia is a common perianestheticand intraoperative complication that can increase the risk of negative outcomes. Body heat is lost through 4 mechanisms during anesthesia: radiation, conduction, convection, and evaporation. Typical warming methods such as forced-air warming devices, conductive heating pads, and heated surgical tables only influence radiative and conductive mechanisms of heatloss. A commercially available heated breathing circuit that delivers gas warmed to 104 °F can easily be integrated into ananesthesia machine. We hypothesized that heating the inspired anesthetic gas to address the evaporative mechanism of heatloss would result in higher body temperature during anesthesia in rhesus macaques. Body temperatures were measured at 5-min intervals in a group of 10 adult male rhesus macaques during 2 anesthetic events: one with a heated anesthesia breathing circuit in addition to forced-air warming, and one with forced-air warming alone. The addition of a heated breathing circuit had a significant positive effect on perianesthetic body temperature, with a faster return to baseline temperature, earlier nadir of initial drop in body temperature, and higher body temperatures during a 2-h anesthetic procedure. Use of a heated anesthesia breathing circuit should be considered as a significant refinement to thermal support during macaque anesthesia, especially for procedures lasting longer than one hour.

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