             IN THE SUPREME COURT, STATE OF WYOMING

                                     2013 WY 96

                                                     APRIL TERM, A.D. 2013

                                                             August 13, 2013

IN THE MATTER OF THE WORKER’S
COMPENSATION CLAIM OF:

JOSEPH O. HAYES,

Appellant
(Petitioner/Claimant),
                                                 S-12-0280
v.

STATE OF WYOMING, ex rel.,
WYOMING WORKERS’ SAFETY AND
COMPENSATION DIVISION,

Appellee
(Respondent).

                     Appeal from the District Court of Platte County
                         The Honorable John C. Brooks, Judge

Representing Appellant:
      Lynn Boak of Lynn Boak, Attorney at Law, LLC, Cheyenne, Wyoming.

Representing Appellee:
      Gregory A. Phillips, Wyoming Attorney General; John D. Rossetti, Deputy
      Attorney General; Michael J. Finn, Senior Assistant Attorney General; Kelly
      Roseberry, Assistant Attorney General.

Before KITE, C.J., and HILL, VOIGT, BURKE, and DAVIS, JJ.
NOTICE: This opinion is subject to formal revision before publication in Pacific Reporter Third.
Readers are requested to notify the Clerk of the Supreme Court, Supreme Court Building,
Cheyenne, Wyoming 82002, of typographical or other formal errors so correction may be made
before final publication in the permanent volume.
KITE, Chief Justice.

[¶1] Joseph O. Hayes, who suffers from cystic fibrosis, sought worker’s compensation
benefits for treatment of pulmonary and other symptoms he believed were related to a
workplace accident. The Office of Administrative Hearings (OAH) upheld the Wyoming
Workers’ Safety and Compensation Division’s (Division) denial of benefits, and the
district court affirmed the OAH decision. Mr. Hayes appeals to this Court, claiming the
OAH erred by failing to find a causal connection between his work injury and his later
medical conditions. He asserts he presented sufficient evidence of the causal connection
by his own testimony and the opinion of a registered nurse. We affirm.

                                          ISSUES

[¶2] Although Mr. Hayes phrases the issues differently, the issues requiring resolution
in this case are:

       1. Whether there was substantial evidence to support the OAH conclusion
          that Mr. Hayes failed to prove the causal connection between his job-
          related broken hand and his later symptoms requiring hospitalization.

       2. Whether the OAH properly disregarded Mr. Hayes’ expert’s report.

       3. Whether medical testimony was required to establish causation.

The State’s statement of the issue contains the same general questions.

                                          FACTS

[¶3] Mr. Hayes was diagnosed with cystic fibrosis when he was a few months old.
Cystic fibrosis is an inherited chronic disease of the exocrine glands that affects the
pancreas, respiratory system and sweat glands. “It is marked by the production of
abnormally viscous mucous by the affected glands, usually resulting in chronic
respiratory infections and impaired pancreatic function.” The American Heritage
Stedman’s Medical Dictionary (2002). As a child, Mr. Hayes had frequent bouts of
pneumonia associated with his condition. When he became older, he used regular
strenuous exercise to keep his lungs relatively free of mucous and, therefore, less
susceptible to infection. In fact, prior to the incident at issue here, Mr. Hayes had not had
any serious lung issues for many years. Although Mr. Hayes exercised regularly, he
disregarded his physicians’ recommendations to use “daily Flutter therapy with
compression and nebulizer” to aid in keeping his airways open.

[¶4] Mr. Hayes was employed as a police officer by the Guernsey, Wyoming police
department. He was required to be certified in the use of a taser and on August 18, 2010,

                                             1
underwent a training session which included him being “tased.” When the taser was
energized, he fell from a kneeling position onto a mat and his chest hit his left hand. He
went to the emergency room, where x-rays showed his left hand was broken. The
emergency room doctor prescribed pain medication and directed him to consult with an
orthopedic surgeon, who recommended surgery.

[¶5] On August 21, 2010, Mr. Hayes went back to the emergency room complaining of
pain in his chest. A chest x-ray did not show any rib fractures, although there were
findings consistent with cystic fibrosis. He was diagnosed with a chest contusion and
prescribed additional pain medication. The next day, August 22, he returned to the
emergency room complaining of “out of control” pain, and received more pain
medication. Mr. Hayes underwent surgery on August 24, 2010, to pin the fractured hand.

[¶6] On September 11, 2010, Mr. Hayes returned to the emergency room with an
“awful” metallic taste causing him to feel nauseous. The emergency room physician
thought the metallic taste was coming from a sinus infection or the pins in his hand. Mr.
Hayes was prescribed antibiotics for the sinus infection.

[¶7] On September 17, 2010, Mr. Hayes again visited the emergency room with
complaints of joint pain, chest tightness, chills, fever, weakness, and coughing. Chest x-
rays showed evidence of cystic fibrosis but were “stable from August.” He was admitted
to the hospital, and Jeffrey A. Cecil, M.D. treated him for the joint pain and gave him
additional antibiotics and respiratory treatments. Mr. Hayes’ condition improved and he
was discharged on September 21, 2010, with a diagnosis of “pneumonia, sinusitis with
cystic fibrosis.”

[¶8] Although the Division granted benefits for the medical treatment associated with
his broken hand, it denied benefits for his hospitalization and associated treatment, stating
that treatment for pneumonia and cystic fibrosis was not related to his work injury. Mr.
Hayes disagreed with the Division’s decision and requested a hearing. He stated his
ailments were the result of being unable to exercise because of his broken hand. The
matter was referred to the OAH for a contested case hearing.

[¶9] At the contested case hearing, Mr. Hayes presented a report from registered nurse
Rhonda Walker (Nurse Walker) in which she opined that his hospitalization was related
to his work accident. Mr. Hayes also testified on his own behalf. The Division presented
an expert medical opinion from Lawrence Repsher, M.D., who stated there was no
evidence of any clinically significant injury to Mr. Hayes’ chest wall or pneumonia, and
he had adult cystic fibrosis.

[¶10] After the hearing, the OAH upheld the Division’s denial of Mr. Hayes’ requests
for benefits on the ground he had not met his burden of proving his hospitalization and
associated treatment were causally connected to the tasing incident. Mr. Hayes petitioned


                                             2
the district court for review, and it affirmed the OAH decision. He then appealed to this
Court.

                              STANDARD OF REVIEW

[¶11] On appeal from a district court’s review of an administrative agency’s decision,
we consider the case as if it had come directly from the administrative agency. Kenyon v.
State ex rel. Wyo. Workers’ Safety & Comp. Div’n, 2011WY 14, ¶ 10, 247 P.3d 845, 848
(Wyo. 2011); Dutcher v. State ex rel. Wyo. Workers’ Safety & Comp. Div’n, 2010 WY
10, ¶ 9, 223 P.3d 559, 561 (Wyo. 2010); Dale v. S & S Builders, LLC, 2008 WY 84, ¶ 8,
188 P.3d 554, 557 (Wyo. 2008). Our review is governed by Wyo. Stat. Ann. § 16-3-
114(c) (LexisNexis 2013):

               (c) To the extent necessary to make a decision and when
             presented, the reviewing court shall decide all relevant
             questions of law, interpret constitutional and statutory
             provisions, and determine the meaning or applicability of the
             terms of an agency action. In making the following
             determinations, the court shall review the whole record or
             those parts of it cited by a party and due account shall be
             taken of the rule of prejudicial error. The reviewing court
             shall:
                     (i) Compel agency action unlawfully withheld or
             unreasonably delayed; and
                     (ii) Hold unlawful and set aside agency action,
             findings and conclusions found to be:
                            (A) Arbitrary, capricious, an abuse of discretion
             or otherwise not in accordance with law;
                            (B) Contrary to constitutional right, power,
             privilege or immunity;
                            (C) In excess of statutory jurisdiction, authority
             or limitations or lacking statutory right;
                            (D) Without observance of procedure required
             by law; or
                            (E) Unsupported by substantial evidence in a
             case reviewed on the record of an agency hearing provided by
             statute.

[¶12] We review the agency’s findings of fact by applying the substantial evidence
standard. Dale, ¶ 22, 188 P.3d at 561. Substantial evidence means “such relevant
evidence as a reasonable mind might accept as adequate to support a conclusion.” Bush v.
State ex rel. Wyo. Workers’ Comp. Div., 2005 WY 120, ¶ 5, 120 P.3d 176, 179 (Wyo.



                                            3
2005) (citation omitted). Findings of fact are supported by substantial evidence if we can
discern a rational premise for the findings from the evidence in the record. Id.

[¶13] Considering an agency determination that the claimant did not satisfy his burden
of proof, we have said:

             If the hearing examiner determines that the burdened party
             failed to meet his burden of proof, we will decide whether
             there is substantial evidence to support the agency’s decision
             to reject the evidence offered by the burdened party by
             considering whether that conclusion was contrary to the
             overwhelming weight of the evidence in the record as a
             whole. If, in the course of its decision making process, the
             agency disregards certain evidence and explains its reasons
             for doing so based upon determinations of credibility or other
             factors contained in the record, its decision will be sustainable
             under the substantial evidence test. Importantly, our review of
             any particular decision turns not on whether we agree with
             the outcome, but on whether the agency could reasonably
             conclude as it did, based on all the evidence before it.

Dale, ¶ 22, 188 P.3d at 561 (citations omitted). An agency’s conclusions of law are
always reviewed de novo, and we will affirm only if they are in accordance with the law.
Moss v. State ex rel. Wyo. Workers’ Comp. Div’n, 2010 WY 66, ¶ 11, 232 P.3d 1, 4
(Wyo. 2010); Dale, ¶ 22, 188 P.3d at 561.

                                     DISCUSSION

[¶14] A claimant for workers’ compensation benefits must prove all of the essential
elements of his claim by a preponderance of the evidence. Middlemass v. State ex rel.
Wyo. Workers’ Safety & Comp. Div’n, 2011 WY 118, ¶ 14, 259 P.3d 1161, 1165 (Wyo.
2011); State ex rel. Wyo. Workers’ Safety & Comp. Div. v. Slaymaker, 2007 WY 65, ¶ 13,
156 P.3d 977, 981 (Wyo. 2007). “‘This burden includes establishing the cause of the
condition for which compensation is claimed and proving that the injury arose out of and
in the course of employment.’” Middlemass, ¶ 14, 259 P.3d at 1165, quoting Hanks v.
City of Casper, 2001 WY 4, ¶ 6, 16 P.3d 710, 711 (Wyo. 2001). Although pre-existing
conditions are excluded from the definition of compensable injury by Wyo. Stat. Ann. §
27-14-102(a)(xi)(F) (LexisNexis 2013), an employee may recover if his employment
“aggravated, accelerated, or combined with the disease or infirmity” to produce the
condition for which compensation is sought. Dutcher, ¶ 14, 223 P.3d at 562.

[¶15] The OAH stated the following regarding the causation evidence in Mr. Hayes’
case:


                                            4
       33. . . . Hayes failed to establish the requisite casual
(sic) connection between the symptoms and treatment from
September 17, 2010, through September 21, 2010 and his
August 18, 2010, left hand injury, which Dr. Bienz surgically
treated on August 24, 2010. Indeed, the evidence presented
did not inform this Office what Hayes was suffering from on
the date he was admitted to Platte County Memorial. Thus, it
was not possible for this Office to connect Hayes’ August 18,
2010, work injury, to the various pain and pulmonary
symptoms he complained of on September 17, 2010. Hayes
may well be correct that he did not have pneumonia during
his hospital stay in September 2010. Indeed, Dr. Repsher
could find no evidence of pneumonia. That situation begs the
question as to what caused Hayes’ symptoms. Hayes himself
acknowledged he was speculating that the electricity from the
tasing caused his joint pain. There was no evidence presented
at [the] hearing establishing the side effects, if any, of tasing.
There was no evidence presented establishing that tasing
causes an onset of sinusitis or other pulmonary symptom[s].
Nor was there any evidence presented that tasing causes joint
pain. Because Hayes’ symptoms between September 17,
2010 and September 21, 2010, do not appear to be the natural
causes of tasing, medical testimony was necessary to
demonstrate the required causal connection. This Office
found Nurse Walker to be completely unqualified to render a
medical opinion and her reasoning not well supported. . . .
[T]his Office overruled the Division’s objection to the
admission of Nurse Walker’s report and ruled her
qualifications went to the weight of the evidence rather than
its admissibility. In reviewing Nurse Walker’s Overview, it is
the clear impression of this Office that Nurse Walker strayed
from reviewing Hayes’ medical records into advocating for
Hayes. Nurse Walker’s credentials do not qualify her to
render medical opinions.

       34. . . . Dr. Repsher is extremely well qualified in
pulmonary diagnosis and care. Dr. Repsher’s opinion was
very narrow. All he said was there was no evidence of a
clinically significant chest wall injury and there was no
evidence of pneumonia from September 17, 2010 through
September 21, 2010. Dr. Repsher’s opinion is accepted.
However, that does not establish the cause of Hayes’


                                5
                symptoms. Thus, this Office is left to speculate as to the
                cause of Hayes’ complaints on September 17, 2010. This
                Office is not willing to do so. It should be noted that even if
                the evidence established Hayes suffered from pneumonia on
                September 17, 2010, there was no evidence connecting this
                condition to the tasing on August 18, 2010. It is the finding
                of this Office that Hayes has not proved the connection
                between his symptoms on September 17, 2010 through
                September 2[1], 2010 . . . to the tasing he underwent on
                August 18, 2010.
                       ....
                        47. There was no evidence presented that Hayes’
                pain and pulmonary symptoms would be the immediate,
                natural or direct result of the tasing or of his broken finger.
                Thus, medical evidence establishing the causal relationship
                between his pain and pulmonary symptoms on September 17,
                2010 . . . was necessary. There was no medical evidence
                presented establishing this causal relationship.
                       ....
                       50. As noted above, there was no medical evidence
                presented that established a causal connection between the
                tasing incident on August 18, 2010 and Hayes’ symptoms on
                September 17, 2010 through September 28, 2010 . . . Indeed,
                there was no evidence presented that established the cause of
                Hayes’ symptoms on September 17, 2010 . . . Also, there was
                no[] evidence presented that tasing aggravates cystic fibrosis
                or causes fevers. Thus, there can be no finding of a material
                aggravation of any condition that Hayes suffered from prior
                to August 18, 2010.

[¶16] Mr. Hayes’ argument that his causation evidence was sufficient is scattered. First,
he challenges the hearing examiner’s decision to disregard Nurse Walker’s opinion and
accept the Division’s expert’s opinion. We note this is not a case where the hearing
examiner denied admission of a proposed expert witness opinion.1 Instead, he admitted

1
  As the hearing examiner recognized, Wyo. Stat. Ann. § 16-3-108(a) (LexisNexis 2013) states: “In
contested cases irrelevant, immaterial or unduly repetitious evidence shall be excluded and no sanction
shall be imposed or order issued . . . unless supported by the type of evidence commonly relied upon by
reasonably prudent men in the conduct of their serious affairs.” The hearing examiner suggested that
reasonably prudent men may rely on the advice or opinion of a nurse in the conduct of their serious
affairs. It is unnecessary to determine, in this case, whether a registered nurse is generally qualified to
offer a medical opinion because we conclude the hearing examiner properly disregarded Nurse Walker’s
opinion due to her lack of expertise in pulmonary issues and her failure to specifically connect Mr. Hayes’
condition to his work injury.


                                                    6
the nurse’s report but ultimately gave it no weight. When conflicting medical opinions
are presented at the contested case hearing, the agency has the

                 responsibility, as the trier of fact, to determine relevancy,
                 assign probative value, and ascribe the relevant weight
                 given to the evidence presented. Clark v. State ex rel.
                 Wyoming Workers’ Safety & Compensation Div., 934 P.2d
                 1269, 1271 (Wyo.1997). The [agency] is in the best
                 position to judge and weigh medical evidence and may
                 disregard an expert opinion if it finds the opinion
                 unreasonable or not adequately supported by the facts
                 upon which the opinion is based. Id.; Matter of Goddard,
                 914 P.2d 1233, 1238 (Wyo.1996).

              Spletzer v. State ex rel. Wyo. Workers’ Safety & Comp. Div.,
              2005 WY 90, ¶ 21, 116 P.3d 1103, 1112 (Wyo. 2005). We do
              not re-weigh the evidence, but defer to the agency’s decision
              so long as it is based on relevant evidence that a reasonable
              mind might accept as supporting that decision. Id., ¶ 22, 116
              P.3d at 1112.

Chavez v. State ex rel. Wyo. Workers’ Safety & Comp. Div’n, 2009 WY 46, ¶ 18, 204
P.3d 967, 971 (Wyo. 2009).

[¶17] Nurse Walker did not have any specific educational background or vocational
experience with cystic fibrosis or pulmonary complications; her opinions appeared to be
based only upon a review of literature covering those medical issues. The hearing
examiner’s refusal to recognize her opinions is, therefore, understandable. Moreover,
although she stated that pulmonary complications can result from a cystic fibrosis
patient’s failure to exercise or ingestion of pain medication, she did not relate a specific
mechanism or process to the clinical findings in Mr. Hayes’ case. As such, Nurse
Walker’s opinion could properly be found to be unreasonable and/or not adequately
supported by the facts. Chavez, ¶ 18, 204 P.3d at 971. The record contains ample
support for the hearing officer’s ruling that Nurse Walker’s opinion was not entitled to
any weight.

[¶18] On the other hand, the hearing examiner accepted Dr. Repsher’s narrow opinion
that there was no evidence of chest wall injury or pneumonia. He concluded Dr. Repsher
was “extremely well qualified in pulmonary diagnosis and care,” and that conclusion is
well supported in the record. Dr. Repsher had extensive education, professional
experience and many publications in the realm of pulmonary disease and care. The
hearing examiner properly weighed the expert evidence, and we will not interfere with
his decision.


                                             7
[¶19] Mr. Hayes also argues the OAH erred by ruling that expert medical testimony was
necessary to establish causation in his case. We have stated that when a single incident is
alleged to have caused an injury, medical testimony may not be required to establish
causation. Hampton v. State ex rel. Wyo. Workers’ Safety & Comp. Div’n, 2013 WY 17,
¶ 14, 296 P.3d 934, 938 (Wyo. 2013); Thornberg v. State ex rel. Wyo. Workers’ Comp.
Div’n, 913 P.2d 863, 867 (Wyo. 1996). This rule is limited, however, to injuries which
are “immediately and directly or naturally and probably the result of an accident.”
Thornberg, 913 P.2d at 867. Regarding proof of aggravation of a preexisting condition
we have stated that “expert medical testimony ordinarily will be required to establish the
link between the worsening of the medical condition and the claimant’s work activities,
rather than some other factor.” Boyce v. State ex rel. Wyo. Workers’ Safety & Comp.
Div’n, 2005 WY 9, ¶ 16, 105 P.3d 451, 456 (Wyo. 2005).

[¶20] As pointed out by Mr. Hayes, we ruled in Herrera v. State ex rel. Wyo. Workers’
Safety & Comp. Div’n, 2010 WY 103, 236 P.3d 277 (Wyo. 2010), that medical testimony
was not necessary to confirm the causal link between Mr. Herrera’s need for a
prescription anti-depression medication and his work-related physical injury. His
medical records and uncontradicted personal testimony that the medication helped control
his pain and blood pressure were sufficient to satisfy the causation element in his case.
Id., ¶¶ 23-24, 236 P.3d at 283-84.

[¶21] In Jacobs v. State ex rel. Wyo. Workers’ Safety & Comp. Div’n, 2013 WY 62, 301
P.3d 137 (Wyo. 2013), by contrast, we ruled medical testimony was necessary. Mr.
Jacobs developed abdominal pain after being prescribed an antibiotic to treat an infection
resulting from his work-related injury and was diagnosed with antibiotic induced colitis.
Id., ¶ 4, 301 P.3d at 139. He continued to suffer from abdominal pain for many years and
eventually the Division denied benefits on the grounds his abdominal pain was not
associated with the work injury. Id., ¶ 5, 301 P.3d at 140. After reviewing voluminous
medical records, the Medical Commission concluded the claimant failed to prove the
causal connection between his on-going abdominal pain and the work injury. We
affirmed the Medical Commission decision because the medical professionals were
unable to attribute his continued abdominal pain to the use of antibiotics years before.
Id., ¶¶ 19-20, 301 P.3d at 145-46. This Court remarked that, in contrast to cases like
those discussed in Thornberg, expert medical testimony was necessary to demonstrate the
causal connection between Mr. Jacob’s continuing abdominal pain and his work place
injury. Id., ¶ 11, n.1, 301 P.3d at 142, n.1. We held the temporal relationship between
his pain and the workplace injury, i.e., his pain started when antibiotics were used to treat
the infection from his work injury, was insufficient to establish the necessary causal link.
Id., ¶¶ 19-25, 301 P.3d at 145-48.

[¶22] In some respects Jacobs is similar to the case at bar. There is arguably a temporal
relationship between Mr. Hayes’ injury and hospitalization for pulmonary and joint pain


                                             8
issues one month later. Nevertheless, like in Jacobs, Mr. Hayes’ subsequent
hospitalization for unexplained lung and joint issues is not the type of immediate and
direct or natural and probable result of an accident contemplated by the rule articulated in
Thornberg. The present case involves complex issues related to cystic fibrosis, infection
and the physical effects of tasing, making medical evidence necessary to establish
causation. There was no credible medical evidence to connect the incidents.

[¶23] Even Mr. Hayes’ position as to the cause of his hospitalization is somewhat
confusing. In response to the Division’s initial denials of his claims, he stated that his
condition had nothing to do with his cystic fibrosis. As his argument developed,
however, he maintained his cystic fibrosis was aggravated because his injuries from the
tasing prevented him from exercising. His expert, Nurse Walker, agreed with that
position and opined the lack of exercise led to pneumonia. Mr. Hayes, however, stated
that he does not believe he had pneumonia (a position with which the Division’s expert
agreed) but that his condition was somehow related to the tasing. Contrary to the
situation in Herrara, Mr. Hayes’ evidence was confusing and contradictory and certainly
did not confirm a causal relationship.

[¶24] Mr. Hayes also argues the fact that no specific cause of the symptoms leading to
his hospitalization was determined should not preclude him from proving his work injury
caused the symptoms. He cites Murray v. State ex rel. Wyoming Workers’ Safety &
Comp. Div’n, 993 P.2d 327 (Wyo. 1999), in support of his argument. In Murray, 993
P.3d at 328, the claimant sought workers’ compensation benefits for a skin condition that
developed after he drew a sample of raw gas at work. After visits to several medical
practitioners, he was eventually diagnosed with an allergy to petroleum products. Id. at
329. The hearing examiner concluded the claimant had failed to meet his burden of
proving the skin condition was related to his employment because he could not identify
the specific source or chemical that caused his condition. Id. at 331.

[¶25] We reversed, stating “causation must be considered in light of all the
circumstances surrounding the incident.” Id. We observed that medical science
“‘probably never will be able to foretell accurately the reaction of every particular human
body to every particular hurt it may sustain in industrial employment.’” Id. at 332,
quoting Baldwin v. Scullion, 50 Wyo. 508, 62 P.2d 531, 539 (Wyo. 1936). Nevertheless,
the medical evidence together with the claimant’s testimony established his skin
condition occurred on the work premises and was triggered by his exposure to chemicals
while at work. It was, therefore, sufficient to establish causation despite the claimant’s
failure to identify the specific cause or chemical leading to his condition. Id. at 333.

[¶26] In Murray, there was a clear relationship between the claimant’s medical condition
and his work activities. Here, other than the fact Mr. Hayes was hospitalized within a
month after the hand injury, there was no clear relationship between the work accident
and his later condition. In addition, his case presents a complexity that did not exist in


                                             9
Murray—Mr. Hayes suffers from a preexisting condition. Mr. Hayes apparently asserts
that he should not be penalized because cystic fibrosis and the effects of tasing are poorly
understood by medical science and his testimony that exercise helps keep his disease
under control and he was unable to exercise because of his condition should be enough.

[¶27] Mr. Hayes did not, however, present any credible evidence that his condition was
actually exacerbated by the tasing incident or his failure to exercise. Mr. Hayes was
required to show his hospitalization was related to his work injury. This is true regardless
of whether his condition was associated with pneumonia or any other aggravation of his
pre-existing cystic fibrosis. He did not make that connection. See Middlemass, ¶ 27, 259
P.3d at 1168 (holding that regardless of whether the injury was an aggravation of a
preexisting condition or a new injury, claimant was required to prove her condition was
caused by her work activities).

[¶28] Finally, Mr. Hayes contends that the hearing examiner did not properly consider
the possibilities that his chest contusion and/or the pain medication caused the condition
that led to his hospitalization. Although Dr. Repsher did not opine as to the cause of Mr.
Hayes’ pulmonary problems, the doctor’s conclusion that he did not suffer a significant
chest wall injury from the tasing incident supports the hearing examiner’s decision that
Mr. Hayes did not meet his burden of proving the causal connection between the chest
contusion from the tasing incident and his subsequent hospitalization. In addition, Mr.
Hayes does not direct us to any other evidence relating the chest contusion to his later
lung condition.

[¶29] With regard to the pain medication, Nurse Walker stated that the side effects of
several pain medications include depressed respiration which can exacerbate cystic
fibrosis. The hearing examiner, of course, rejected her opinion and we have affirmed that
ruling. Furthermore, Mr. Hayes does not direct us to any medical evidence showing that
he actually had depressed respiration as a result of the pain medication or that it led to an
aggravation of his preexisting condition.

[¶30] In sum, Mr. Hayes maintains that he had been successful in keeping his cystic
fibrosis under control for many years by engaging in regular, strenuous exercise. He was
unable to exercise because of his work injury and within a month he experienced
respiratory problems and joint pain. According to him, it is a natural conclusion that the
injury led to his subsequent ailments. The problem with his argument is that he did not
prove the critical causal link with credible medical evidence. Substantial evidence exists
in the record to support the hearing examiner’s decision to reject the causation evidence
offered by Mr. Hayes and that conclusion was not contrary to the overwhelming weight
of the evidence. See Dale, ¶ 22, 188 P.3d at 561.

[¶31] Affirmed.



                                             10
