Just as we were publishing last week’s update on OR fires a story out of the UK reminded us that OR fires are not the only cause of burns in the OR. A 58 y.o. man underwent surgery for a renal cyst and ended up with third degree burns on his buttock and hip that ultimately required skin grafting (The Guardian 2014). The cause - a warming blanket. We’ve briefly noted burns from warming blankets in our previous columns on iatrogenic burns (see our Patient Safety Tips of the Week for June 1, 2010 “Iatrogenic Burns” and October 5, 2010 “ ”). But this one had a unique twist. During the surgery a cold saline bag was in contact with a sensor, leading the system to perceive that the patient was hypothermic and thus increase the temperature. Investigation and a subsequent court case revealed that two other patients had received minor burns in similar circumstances at that hospital and that staff had been inadequately trained in use of the devices (Pilkington 2014).
Avoiding perioperative hypothermia improves patient outcomes by reducing the risks of infections and coagulopathy, facilitating recovery, etc. Avoiding perioperative hypothermia has become a quality focus for SCIP, Joint Commission, CMS, and other pay-for-performance programs. Warming blankets and related devices are extremely important tools used to help maintain perioperative normothermia. When used correctly they are effective, efficient and safe. We found cases of thermal injuries related to warming blankets going back as far as the 1960’s. Almost every reported case of thermal injury related to such devices had unusual additional factors or circumstances that contributed to the occurrence of thermal injury.
Poor tissue perfusion has long been recognized as a risk factor for thermal injuries with warming devices. Hence such devices typically have a warning to avoid use in patients with peripheral vascular disease, low cardiac output, aortic cross-clamping, or other causes of poor perfusion. Sometimes poor tissue perfusion may be aggravated by perioperative events. In a 3-year old having surgery for transposition of the great arteries, second- and third-degree burns developed and corresponded anatomically to the warm air exit holes of the warming blanket (Truell 2000). In addition to poor tissue perfusion related to the chronic cyanotic heart disease, the patient had significant intraoperative bleeding treated with controlled hypotension and blood product replacement and received low-dose pressor agents.
Probably the best known factor reported in burns related to warming blankets has been the practice of “hosing” or “free-hosing”. This refers to simply using the hose of the warming device without the blanket attachment and allowing the hot air to blow directly onto the patient, forcing the hot air onto one focused area of the body (Marders 2002). In an analysis of the ASA Closed Claims Project, 13 of 15 burns related to warming blankets were due to “hosing” (Mehta 2013). The occurrence of “hosing” even prompted one manufacturer of warming blankets to initiate a campaign www.stophosing.com to provide anti-hosing materials for healthcare facilities and practitioners (Augustine 2002). Mehta recommended that if you anticipate your patient might need active warming during surgery you should apply the disposable warming blanket before surgical draping (since the cost of the disposable blanket is far less than the cost of a burn injury).
And burns may develop from “hosing” in relatively short periods. A case was described in which a patient complained of feeling cold after surgery so 43o C hot air was blown directly on the patient for 30 minutes via the hose of a warming device that was not connected to a blanket (Chung 2012). The patient developed a burn in the left lower abdomen. The patient had also had epidural anesthesia with a blocking level of T10 so it is unclear whether residual loss of sensation in the area might have been an additional contributory factor.
A case that nicely describes how extrinsic factors may contribute to the risk of burns from warming devices was described by Hansen and colleagues (Hansen 2014). They described a case in which a 44-year-old man undergoing ambulatory ENT surgery sustained a 5% total body surface first-degree burn on his lower and lateral torso and upper thigh related to use of a new forced-air warming “gown” system. Because the table on which the patient lay would be rotated to facilitate access to the mouth, special straps were applied to the patient to prevent him from falling off the table. The warming device was set to a “high” setting (43o C) for almost a 4-hour surgical procedure. In addition, during the procedure several instruments, retractors, and other operative devices had been placed on top of the warming device over the patient’s abdomen. On completion of the surgery it was noted the patient had thermal injuries to his flank, lateral torso and upper thigh. The skin abnormalities corresponded to areas underneath the warming device inflow hose and the small airflow perforations in the warming gown. The authors did a root cause analysis and simulated reconstruction that found several very valuable lessons learned. Basically, rather than dispersing the heat over the whole “gown” the heat was confined to a small area bounded by the special straps, the instruments on the abdomen, and the table. The rest of the “gown” was underinflated.
The other key finding was that despite the temperature setting being on “high” for the duration of surgery, the patient’s temperature never rose above 35.7o C during the procedure. The authors retrospectively note that should have been a flag that something was not right. The patient’s temperature was being monitored via the axilla and staff may have attributed some of the problem to the fact that axillary temperatures are less reliable than oral, rectal or bladder temperatures.
Their conclusions and recommendations, plus those in the accompanying editorial (Rohr 2014), would be:
Note: We have a special comment about instruments placed on top of the patient. In our previous two columns on iatrogenic burns we noted instances where flash-sterilized tools or instruments that were “too hot to handle” were placed on drapes overlying the patient, resulting in burns to the patient.
Another paper highlighting multiple contributory factors described burns in two infants that were just opposite the exit vents of their warming blankets (Azzam 1995). In both cases the high setting (45o C) was used initially and converted to the medium setting once the infant’s temperature reached 37o C. They felt that the combination of a warming cover, plastic drape, and surgical sheets may have created a microenvironment which prevented dissipation of the heat. They note the FDA had previously mentioned contact of heated plastic with skin as a contributing factor to some warming blanket-related thermal injuries. Azzam and Krock’s recommendations were:
The role of sensory loss may also be significant. Warnings about risks of using warming blankets in diabetic patients go way back. While many of those warnings were lumped together with other warnings about using such devices in patients with poor tissue perfusion, the other significant factor in diabetics is neuropathy and loss of sensation. One report (Uzun 2010) described a 64-year-old man with type 2 diabetes of 12 years’ duration who developed a third-degree burn on his ankle after coronary bypass surgery. He had begun complaining of cold after surgery so was heated with a forced-air warming system. The nozzle of the device was not connected to the blanket and hot air at 40–43°C was blown directly onto his legs for nearly 2 hours. In addition to absent pedal pulses the 10-g-Semmes–Weinstein monofilament test revealed reduced sensation suggestive of diabetic peripheral neuropathy. In the case we noted earlier (Chung 2012) we speculated that loss of sensation related to epidural anesthesia might have been an additional factor contributing to a burn. And in a case noted below (Khan 2011), due to a hot pack rather than a warming blanket, loss of sensation in a paraplegic patient likely contributed to the burn.
The role of pressure, particularly over bony prominences, has also contributed in some cases. In one of the earliest reports of injuries related to thermal blankets in the OR, Scott reported 3 cases of skin and tissue necrosis in direct relationship to thermal blankets (Scott 1967). Each patient had prolonged exposure to warming blankets during cardiac surgery, often first at room temperature then at 40-42o C. The analysis focuses as much on the role of pressure over bony protruberances as on thermal injury. However, in one case a metal plate overlying the skin might have acted as a heat conductor. Crino and Nagel also found burns overlying bony prominences in two patients with burns related to warming blankets (Crino 1968). In describing a sacral thermal burn due to use of a “hot pack” in a paraplegic patient who had lost sensation in the area being treated Khan et al. (Khan 2011) noted multiple factors played a role in the tissue damage. In addition to the patient being insensate to the heat, the duration of the treatment was longer than usual and the hot pack was encased in its synthetic case, lacking the usual padding or towel wraps used with such treatments. That additional pressure likely played a role. Note that the risk equation for burns has usually been described as “temperature x duration”. Perhaps it should be “temperature x duration x pressure”. In fact, in view of the “hosing” injuries and the cases described with very focused exposure to hot air (Hansen 2014, Uzun 2010, Chung 2012) the role of surface area exposed to heat needs to be considered as well. Perhaps the risk equation should be “temperature x duration x pressure x area of exposure”.
Crino and Nagel (Crino 1968) also called attention to the need to consider duration of the procedure. Note that we have always recommended an issue to be discussed during the pre-op huddle/briefing (see, for example, our July 22, 2014 Patient Safety Tip of the Week “More on Operating Room Briefings and Debriefings”) is the expected duration of the procedure and what contingencies need to be considered if that duration is exceeded. The usual considerations would be things like additional doses of prophylactic antibiotics, repositioning of patients to avoid nerve injuries or decubiti, and consideration for DVT prophylaxis. It would probably be wise to add consideration of factors related to warming blankets or related devices (eg. skin examination, temperature settings, etc.) to your pre-op huddle/briefing.
And, lest one get the impression that burns suffered from misuse of or malfunction of warming blankets and related devices, a case of a fatal 30% full-thickness total body surface area burn has been reported (Sadove 1992).
Note also that, though we have focused on warming blankets and related devices in today’s column, many of the same contributory factors and considerations also apply to use of hot packs, hot water bottles and similar devices. In Massachusetts (Massachusetts DPH 2014) there were 16 serious reportable events related to serious injury or death from burns in 2013, up from 6 in 2011 (though the definition of such events was expanded in 2012). Though some of these were due to operating room fires or hot beverage spills, others were due to heating packs applied without protective cover, for too long a period of time, or not meeting safe standards (e.g. improvised heating pads). Factors such as insensitivity to pain and pressure over bony prominences may contribute to these injuries as well. In describing a thermal burn due to use of a “hot pack” in a paraplegic patient who had lost sensation in the area being treated Khan et al. (Khan 2011) noted multiple factors played a role in the tissue damage. In addition to the patient being insensate to the heat, the duration of the treatment was longer than usual and the hot pack was encased in its synthetic case, lacking the usual padding or towel wraps used with such treatments.
To reiterate recommendations to avoid thermal injuries from warming blankets and related devices:
While today’s focus is on warming blankets and related devices you’ll find many valuable lessons about other iatrogenic burns and OR fires in our prior columns.
Our prior columns on iatrogenic burns:
Our prior columns on surgical fires:
Press Association. Hospital trust faces fine after surgery patient is burned by warming blanket. The Guardian 2014; Friday 12 December 2014
Pilkington D. The hi-tech hospital mattress that left this man with third-degree burns: Equipment similar to an electric blanket overheated during surgery. The Daily Mail 2014; 14 October 2014
Truell KD, Bakerman PR, Teodori MF, Maze A. Third-degree burns due to intraoperative use of a Bair Hugger warming device. Annals of Thoracic Surgery 2000; 69(6): 1933-1934
Marders J. FDA Encourages the Reporting of Medical Device Adverse Events: Free-Hosing Hazards. APSF Newsletter 2002; 17(3): Fall 2002
Mehta SP. Burn Injuries From Warming Devices in the Operating Room. American Society of Anesthesiologists Newsletter 2013; 77(2): 16-17
Stop Hosing website.
Augustine S. Misuse of Forced-Air Warming Devices Causes Burns. APSF Newsletter 2002; 17(1): Spring 2002
Chung, K., Lee, S., Oh, S.-C., Choi, J., & Cho, H.-S. (2012). Thermal burn injury associated with a forced-air warming device. Korean Journal of Anesthesiology 2012; 62(4): 391-392
Hansen EK, Apostolidou I, Layton H, et al. Thermal Burn Associated with Intraoperative Convective Forced-Air Warming Blanket (Bair Paws™ Flex Gown System). A&A Case Reports 2014; 3(7): 81-83
Rohr JM. Editorial Comment: Manufacturer’s Response to Thermal Burn Associated with Intraoperative Convective Forced-Air Warming Blanket (Bair Paws™ Flex Gown System). A&A Case Reports 2014; 3(7): 84
Azzam FJ, Krock JL. Thermal Burns in Two Infants Associated with a Forced Air Warming System. Anesth Analg 1995; 81(3): 861
Uzun G, Mutluoglu M, Evinc R, Ozdemir Y, Sen H. Severe burn injury associated with misuse of forced-air warming device. J Anesth 2010; 24: 980-981
Khan MA, Jamnadas-Khoda B, Gorman M, et al. Iatrogenic burns from the use of hot packs in paraplegic insensate patients. Injury Extra 2011; 42(6): 64-65
Scott SM. Thermal blanket injury in the operating room. Arch Surg 1967; 94(2): 181
Crino MH, Nagel el. Thermal Burns Caused by Warming Blankets in the Operating Room. Anesthesiology 1968; 29(1): 149-150
Sadove RC, Furgasen TG. Major thermal burn as a result of intraoperative heating blanket use. J Burn Care Rehabil 1992; 13(4): 443-445
Massachusetts Department of Public Health. Public Health Council Presentation on Serious Reportable Events in Massachusetts Hospitals – August 2014
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