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 “More
Iatrogenic Burns”). 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:
References:
Press Association. Hospital trust faces fine after surgery
patient is burned by warming blanket. The Guardian 2014; Friday 12 December
2014
http://www.theguardian.com/uk-news/2014/dec/12/hospital-fine-burn-warming-blanket-surgery-maidstone
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
http://www.annalsthoracicsurgery.org/article/S0003-4975%2800%2901322-9/fulltext
Marders J. FDA Encourages the
Reporting of Medical Device Adverse Events: Free-Hosing Hazards. APSF
Newsletter 2002; 17(3): Fall 2002
http://www.apsf.org/newsletters/html/2002/fall/09reportevents.htm
Mehta SP. Burn Injuries From
Warming Devices in the Operating Room. American Society of Anesthesiologists Newsletter
2013; 77(2): 16-17
http://depts.washington.edu/asaccp/sites/default/files/pdf/Click%20here%20for_1.pdf
Stop Hosing website.
http://www.stophosing.com/spw/
Augustine S. Misuse of Forced-Air Warming Devices Causes
Burns. APSF Newsletter 2002; 17(1): Spring 2002
http://www.apsf.org/newsletters/html/2002/spring/13warmingdevices.htm
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
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3337390/
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
http://journals.lww.com/aacr/Abstract/2014/10010/Thermal_Burn_Associated_with_Intraoperative.1.aspx
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
http://link.springer.com/article/10.1007/s00540-010-1031-1
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
http://archsurg.jamanetwork.com/article.aspx?articleid=565611
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
http://www.mass.gov/eohhs/docs/dph/quality/sres/2014-sre-presentation.pptx
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