a b s t r a c t

Introduction: hand injuries represent the most common and potentially Serious injuries associated with the use of snow blowers. Little research has been conducted on a national scale to examine these types of injuries. There- fore, the purpose of the study was to examine hand injuries among patients treated in an emergency department (ED) related to attempting to clear snow out of a clogged snow blower.

Methods: Data were obtained from the National Electronic Injury surveillance System for the years 2009-2017. National estimates of ED visits for hand injuries associated with the use of a snow blower were analyzed by na- ture of injury, age, and disposition. Trends in age adjusted rates were also obtained.

Results: During the 10 year period, there were 27,826 hand injuries treated in emergency departments associated with the use of snow blowers. The majority of the injuries were fractures and lacerations, with an additional 22% being amputations. The majority (95%) were among males and most occurred among middle aged adults. Over- all, hand injuries associated with the use of snow blowers declined during the study period.

Conclusions: Hand injuries remain the main threat of injury among snow blower operators. While trends are de- clining, given the seriousness of the injuries involved, further public health education campaigns and design modifications are warranted.

(C) 2019

Introduction

Hand injuries represent a potentially serious injury associated with reaching into snow blowers [1-8]. Trends in snowfall have changed over time, which has resulted in a lower total snowfall in the U.S. since 1970. However, during the same timeframe there has been an in- crease in extreme weather events. This in turn has caused some individ- ual storms to produce heavier volumes of snowfall during a shorter period of time [9]. Given these changes in weather patterns, it is likely that snow blowers may be increasingly used to remove larger amounts of wet snow, thereby predisposing the user to injuries associated with removing snow from clogged machines. Previous case studies focusing on serious hand injuries have shown that the majority of persons were injured while attempting to clear snow from a clogged machine and were subsequently struck by the moving auger blade, which works to discharge the snow away from the machine. The results were injuries inclusive of amputations, lacerations and/or fractures of the hand and/or fingers [1-8].

While improvements in the design of machines, such as operator

presence controls that stop the machine when the operator releases

* Corresponding author.

E-mail addresses: [email protected] (B. Hammig), [email protected] (C. Jones).

the power lever, have occurred over time, hand injuries remain a prob- lem. While relatively uncommon compared to other injuries, injuries associated with snow blower use have the potential to be severe, specif- ically if the injury is to the hand, which can result in a life altering injury to those afflicted [1-4]. Due to the lack of population based studies re- garding snow blower injuries, the change and improvement to the de- sign of such products over time, as well as changes in extreme weather events, we sought to examine national data to describe injuries presenting to emergency departments that were associated with the biggest threat to using a snow blower, which is reaching into a snow blower to clear the machine of clogged snow.

Methods

Using data from 2008 to 2017, we analyzed the National Electronic Injury Surveillance System for hand injuries associated with reaching into a snow blower [10]. The NEISS surveillance system, oper- ated by the Consumer Products Safety Commission (CPSC), collects in- jury data on visits to emergency departments that are associated with consumer products. The NEISS is a nationally Representative sample of

U.S. hospitals that have a minimum of 6 beds and a 24 hour ED, and pro- vides estimates on initial injury visits treated in hospital emergency rooms [10].

https://doi.org/10.1016/j.ajem.2019.06.042

0735-6757/(C) 2019

786 B. Hammig, C. Jones / American Journal of Emergency Medicine 38 (2020) 785-788

Measures

Cases were defined as anyone presenting to an emergency depart- ment for an injury to the hand or fingers related to the use of a snow blower (product codes 1458, 1459, 1406). In an effort to limit the scope of injuries to those attributed to sticking a hand into a snow blower to clear clogged snow, we analyzed the narrative text entries which help to delineate the circumstances of the injury. After segmenting injuries by consumer product (snow blower) and body part injured (hand or fingers), we then analyzed narrative text entries. This ensued in a 3 stage process in which we first omitted cases in which the narrative text clearly demonstrated that the injury was not due to reaching into the snow blower. For example, “48 yom fell while snow blowing at home and injured handdx/left hand sprain” and “24yom cut rt 2nd finger on wheel of snow blower. dx; finger lac” This removed 10.2% of our sample of injury cases. Next, we reviewed the remaining cases for indications that the injury was due to reaching into the snow blower. This was defined by searching the text narratives for terms or phrases inclusive of “reaching in” “cleaning out” “unclog” and “stuck hand in” or similar phrasing, such “clear clog” or combina- tions of the aforementioned terms that indicated the patient was attempting to clear lodged snow. (e.g. “40 yr old male reached into snow blower to dslodge clogs and lac finger” and “34ym unclogging his snow blower&got finger caught in the bladeNNopen fx/lac”). This left a portion of narrative text entries that were suspicious of reaching into a snow blower to unclog snow, but not conclusive. To increase the sensitivity of our definition, we then examined these remaining nar- rative texts and if the diagnosis was also amputation, we labeled the in- cident as an injury that occurred while trying to clear clogged snow from the machine. For example, the following texts were labeled as such: “28yom amputated finger while using snow blower” and “rt 3rd and 4th finger amputation.48yom amputated finger while using a snow blower.” The justification for this latter coding scheme is that the most likely scenario for a hand or finger amputation when using a snow blower is if the patient was reaching into the machine to clear clogged snow. Other variables measured included gender, disposition, age, and principal diagnosis, inclusive of fractures, lacerations, avul- sions, and amputations. With regard to amputations, injuries were fur- ther stratified into partial or complete amputations by examining the narrative text associated with the injury diagnosis. This study was ex- empt from approval by the Institutional Review Board (IRB).

Statistical analysis

Data analyses were conducted using STATA 13.1. Sample weights were applied to the patient visits to produce national estimates. To ac- count for the multistage sampling design of the NEISS, all estimates were calculated incorporating the sample design variables into the anal- yses. Average annual rates and age adjusted rates were calculated using

U.S. Census Bureau bridged race estimates as the denominator. Because

Table 1 Average annual number, percent, and rate of snow blower injuries related to reaching into a snow blower, males by age group, 2008-2017.

N % (95% CI) Average annual rate per 100,000 Total 2783 100 1.8 (1.1-2.5)

Age group

b+14	16	b1.0	-
15-24	197	7.1 (5.2-9.7)	0.9 (0.39-1.4)
25-34	370	13.3 (10.5-16.7)	3.2 (1.6-4.7)
35-44	530	19.1 (15.9-22.6)	2.6 (1.4-3.8)

45-54 826 29.7 (25.5-34.2) 3.8 (2.3-5.4)

55-65 493 17.7 (14.8-21.1) 2.6 (1.5-3.8)

65+ 350 1.8 (9.5-16.6) 1.8 (1.0-2.6)

10 year study period, resulting in an average annual frequency of 2929 cases per year. Among those injured, 95% were male, which resulted in an average annual rate among males of 1.8 ED visits per 100,000. Among males, those aged 25-34 years and those aged 45-54 years ex- hibited the highest average annual rate of injuries. See Table 1.

Fractures and lacerations accounted for the majority of injuries treated in ED’s, with 42.8% and 28.3%, respectively. Amputations, which are likely the most traumatic injury associated with snow blower usage, accounted for 22.2% of all hand injuries. Additionally, 15% of those injured were hospitalized or transferred to another care facility. See Table 2. Among those presenting with amputation injuries, 26.8% were categorized as partial amputations, 45.6% were complete amputa- tions of either a fingertip or digit amputation, and 27.4% were complete multiple fingertip or digit amputations. None appeared to involve the thumb. This resulted in 6512 amputations during the 10 year study period.

Trends in age adjusted rates of hand injuries associated with snow blowers have changed over time, as depicted in Fig. 1. Graphically, rates increased between 2008 and 2010, though this was a non- significant change [annual percent change (APC) = 17.0, P = .6]. How- ever, rates of hand injuries significantly declined between 2010 and 2017 (APC = -13.2, P b .01).

4. Discussion

Hand injuries represent a potentially serious injury associated with reaching into snow blowers. The finding that amputations, fractures, and avulsions account for almost 70% of all hand injuries signifies that problems associated with unclogging snow blowers continue to repre- sent a serious hazard among users. Snow blowers are most likely to clog when the snowfall is wet and heavy. Because of this, recent design

Table 2 Average annual number and percent of emergency department visits for hand injuries re- lated to reaching into a snow blower: diagnoses and disposition, U.S., 2008-2017.

the number of people using snow blowers is not known and could not be adequately estimated, rates per 100,000 are based on the U.S. popu- lation. Significance of trends over the 10 year study period was esti-

mated using Joinpoint regression analyses [11]. The Joinpoint

Injury diagnosis

No. of

visits-weighted (95% CI)

Total percent (95%

CI)^a

regression model was fitted to estimate annual percent change (APC) in age adjusted rates and to identify possible joinpoints defined as years at which trends changed significantly. Because we analyzed 10 years of data, a maximum of 1 joinpoint was allowed. Sample size es- timates based on fewer than 20 raw cases (or 1200 weighted cases), or

which had a coefficient of variation equal to or N30%, were considered unreliable [10].

Fracture 1254 (724-1784) 42.8 (37.3-48.5)

Laceration 828 (502-1155) 28.3 (23.8-33.2)

Amputation 651 (329-974) 22.2 (17.2-28.2)

Avulsion 86 (34.3-138) 2.9 (1.9-4.5)

Contusion 38 (9-66) 1.3 (0.6-2.6)

Other 71 (20-123) 2.5 (1.2-4.8)

Disposition

Treated and released 2475 (1462-3488) 84.5 (79.7-88.4)

Hospitalized/transferred and

hospitalized

438 (252-623) 14.9 (11.1-19.8)

3. Results

There were a total of 29,287 hand injuries treated in ED’s that were associated with reaching into a snow blower to clear snow during the

Other ^{b b}

Abbreviations: CI, confidence interval.

^a Percents may not add up to 100% due to rounding.

^b Denotes figure does not meet standard for reliability or precision.

B. Hammig, C. Jones / American Journal of Emergency Medicine 38 (2020) 785-788 787

Fig. 1. Age-adjusted rates of hand injuries associated with reaching into a snow blower by year, 2008-2017.

changes in snow blower machines have evolved. New models on the market include a 3 stage snow blower that is manufactured and marketed to specifically break down and discharge heavy, wet snow. This design appears very similar to the more commonly used 2 stage models (in which a front auger picks up the snow and an internal impel- ler discharges the snow), except that it splits the front auger into 2 stages. First, two collection augers located on the front of the machine collect the snow and move it to the middle of the machine, where a 2nd high speed auger breaks down heavy snow and delivers it to the 3rd internal impeller where it is then discharged into the air. This is the impeller linked to the vast majority of hand injuries. However, no evidence is yet available to determine if these machines are less likely to clog. Additionally, depending on how they are advertised, 3 stage models could invite people to become overconfident in the machines capability and invoke them to attempt to clear deeper and heavier snow than is recommended for the machine. This could increase the risk of clogging of the impeller, and subsequently pose an injury risk. To date, 2 stage snow blowers remain the most common form on the market.

We anecdotally analyzed safety sections of operator manuals chosen from 8 top brands recently available at major big box hardware stores. All manuals provided warnings stating that unclogging the discharge shoot of snow was a hazardous activity and that hands should never be placed in or near the discharge shoot. Some manufacturers specifi- cally state that amputation and sever lacerations can occur. Further- more, directions are given describing how to unclog a discharge shoot by ensuring the engine is off and using either an included “hand tool” to discharge the snow, though some manufacturers specifically stated user should find and use a “stick.” One major manufacturer recently in- cluded information about the possibility that rotational force could be stored up in the augers when they become clogged, that could then ro- tate once the snow is cleared (even though the engine is off), thereby resulting in possible injury. Though anecdotal evidence [6,8], (including the narrative text of injury occurrence in the present study) does exist for this stored rotational force effect when the engine is off, we were un- able to corroborate this with any evidence via published sources in the engineering field.

While we found a decreasing trend in injuries, it is not known

whether this was due to better communication of safety information, better design of machines, or less usage, (and hence exposure) due to changing weather patterns. As such, we cannot make any conclusions on the risk of injury over time. With warming temperatures and higher

humidity, the snow that is falling tends to be wetter and heavier [9,12], which is the main cause of clogged machines. This could lend itself to more “outbreaks” of hand injuries during extreme weather events. While we found an overall decreasing trend in injuries, it may be that when injuries do occur, they occur in larger frequency in a very Short period of time during these extreme snowfalls. Therefore, there may be opportune time around these extreme winter events where public service announcement could encourage the safe use of snow blowers. Additionally, emergency departments may be advised to prepare for an influx of hand trauma cases during these events and/or be equipped to staff or refer patients to hospitals with hand trauma surgeons.

Some limitations exist with the NEISS data, including that the fre- quency of injuries are under-represented, as NEISS reports only emer- gency department visits. Also, because we do not know the number of people who use snow blowers or for what length of time, exposure data is void. Therefore, it is impossible to estimate the true incidence of snow blower-related injuries or to compare the relative risk of snow blower injuries with other types of similar products. Also, we opted for a more sensitive case definition of reaching into a machine to clear clogged snow, which could result in an overestimate of associ- ated injuries. However, given the justification of our case definition, we don’t feel this is a major weakness. Strengths of our study include the use narrative text entries to further delineate hand injuries, and the large, national sample on which to provide epidemiologic analyses. In conclusion, snow blower injuries, while relatively small in num- ber, continue to present a potentially serious, life altering injury to those affected. Reduction and elimination of these injuries will require collaborative efforts between health professionals, engineers, and man- ufacturers. Findings from this study support that the most serious inju- ries have been narrowed to those involved with reaching into a machine to clear clogged snow. Therefore, Manufacturers are urged to continue to reflect on injury findings associated with their products and modify designs to make the product safer for users. Lastly, an increased empha- sis on awareness of injury is warranted, particularly when extreme

weather events may be forecast.

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