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                                  Nebraska Supreme Court A dvance Sheets
                                          298 Nebraska R eports
                                          EWERS v. SAUNDERS COUNTY
                                              Cite as 298 Neb. 944




                             T. Louise Ewers, personally and as Personal
                               R epresentative of the Estate of Mickley
                                  (Michael) Lynn Ellis, appellant, v.
                                Saunders County, Nebraska, a political
                                     subdivision, et al., appellees.
                                                   ___ N.W.2d ___

                                        Filed February 9, 2018.   No. S-17-251.

                1.	 Pretrial Procedure: Appeal and Error. Decisions regarding discovery
                    are directed to the discretion of the trial court, and will be upheld in the
                    absence of an abuse of discretion.
                2.	 Pretrial Procedure: Proof: Appeal and Error. The party asserting
                    error in a discovery ruling bears the burden of showing that the ruling
                    was an abuse of discretion.
                3.	 Summary Judgment: Appeal and Error. In reviewing a summary
                    judgment, an appellate court views the evidence in the light most
                    favorable to the party against whom the judgment was granted and
                    gives that party the benefit of all reasonable inferences deducible from
                    the evidence.
                4.	 Pretrial Procedure: Evidence. A party’s failure to make a timely
                    and appropriate response to a request for admission constitutes an
                    admission of the subject matter of the request, which matter is conclu-
                    sively established unless, on motion, the court permits withdrawal of
                    the admission.
                5.	 Rules of the Supreme Court: Pretrial Procedure. Neb. Ct. R. Disc.
                    § 6-336 is self-enforcing, without the necessity of judicial action to
                    effect an admission which results from a party’s failure to answer or
                    object to a request for admission.
                6.	 Rules of the Supreme Court: Pretrial Procedure: Evidence: Proof.
                    Neb. Ct. R. Disc. § 6-336 is not self-executing. Thus, a party that seeks
                    to claim another party’s admission, as a result of that party’s failure
                    to respond properly to a request for admission, must prove service
                    of the request for admission and the served party’s failure to answer
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              Nebraska Supreme Court A dvance Sheets
                      298 Nebraska R eports
                        EWERS v. SAUNDERS COUNTY
                            Cite as 298 Neb. 944

     or object to the request and must also offer the request for admission
     as evidence.
 7.	 Rules of the Supreme Court: Pretrial Procedure. If the necessary
     foundational requirements are met and no motion is sustained to with-
     draw an admission, a trial court is obligated to give effect to the pro-
     visions of Neb. Ct. R. Disc. § 6-336 which require that the matter be
     deemed admitted.
 8.	 Malpractice: Physician and Patient: Proof: Proximate Cause. In
     a malpractice action involving professional negligence, the burden of
     proof is upon the plaintiff to demonstrate the generally recognized
     medical standard of care, that there was a deviation from that standard
     by the defendant, and that the deviation was a proximate cause of the
     plaintiff’s alleged injuries.
 9.	 Malpractice: Physicians and Surgeons: Proximate Cause: Damages.
     In the medical malpractice context, the element of proximate causation
     requires proof that the physician’s deviation from the standard of care
     caused or contributed to the injury or damage to the plaintiff.
10.	 Negligence: Proximate Cause. A defendant’s negligence is not action-
     able unless it is a proximate cause of the plaintiff’s injuries or is a cause
     that proximately contributed to them.
11.	 Negligence: Proximate Cause: Words and Phrases. A proximate cause
     is a cause that produces a result in a natural and continuous sequence
     and without which the result would not have occurred.
12.	 Proximate Cause: Words and Phrases. A defendant’s conduct is a
     proximate cause of an event if the event would not have occurred but
     for that conduct, but it is not a proximate cause if the event would have
     occurred without that conduct.
13.	 Expert Witnesses: Proximate Cause. Expert testimony is almost
     always required to prove proximate causation.

   Appeal from the District Court for Saunders County: James
C. Stecker, Judge. Affirmed.
   Larry R. Demerath, of Demerath Law Office, and Justin B.
Demerath, of O’Hanlon, McCollom & Demerath Law Firm,
for appellant.
  Joseph S. Daly and Mary M. Schott, of Sodoro, Daly,
Shomaker & Selde, P.C., L.L.O., and J. Scott Paul, of McGrath,
North, Mullin & Kratz, P.C., L.L.O., for appellees Advanced
Correctional Health Care, Inc., et al.
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           Nebraska Supreme Court A dvance Sheets
                   298 Nebraska R eports
                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

  Heavican, C.J., Miller-Lerman, Cassel, Stacy, K elch, and
Funke, JJ.
  K elch, J.
                       INTRODUCTION
   This appeal arises from the in-custody death of Mickley
(Michael) Lynn Ellis. T. Louise Ewers, personally and as per-
sonal representative of Ellis’ estate, brought a wrongful death
action alleging medical malpractice by Advanced Correctional
Healthcare, Inc. (ACH), and its agents in their individual and
official capacities (collectively Appellees). Ewers also filed
suit against Saunders County, the Saunders County sher-
iff’s office, Saunders County Corrections, Saunders Medical
Center, and Dan Scott, but those causes of action are not
relevant to this appeal. Ewers now appeals from the orders
of the district court for Saunders County that denied her dis-
covery motions and granted Appellees’ motion for summary
judgment. We conclude that the district court did not err, and
we affirm.
                        BACKGROUND
   Ellis was incarcerated in the Saunders County jail on May
27, 2010. During the morning of June 22, he spoke with
Mallory Reeves, a licensed practical nurse employed by ACH,
the medical contractor hired by Saunders County. In her notes,
Reeves stated that Ellis wanted to talk to a counselor about
nightmares he was having and that she told him to fill out a
“sick call,” which is how an inmate reports medical issues.
   Instead of filling out a “sick call,” Ellis filled out a “kite”
form, which is how an inmate relays reports or requests to
jail personnel. In the form, he requested help with his night-
mares. He mentioned that he was having chest pain and “hard”
breathing when he awoke from the nightmares and that he was
waiting to find the right medication to help him. Ellis had a
history of chest pain and shortness of breath after nightmares
and, about 3 weeks prior, had been taken to a hospital for men-
tal health issues.
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                  EWERS v. SAUNDERS COUNTY
                      Cite as 298 Neb. 944

   After receiving the “kite” form, jail personnel completed
an incident narrative. According to the incident narrative, jail
personnel informed Reeves of the physical complaints Ellis
described on the “kite” form, and she responded that it was not
a medical issue, as Ellis was requesting to speak with some-
one, and that there was not anything she could do for him.
At her deposition, Reeves did not recall that conversation but
admitted that chest pain was a serious complaint that could be
life-threatening. As a result of the “kite” form, an appointment
was made for Ellis to speak with a pastor.
   Ellis made no further complaints until 3:40 a.m. on June
25, 2010. He told jail personnel that he was having trouble
breathing and that his back hurt. At 4 a.m., jail personnel
contacted Mary Scherling, a nurse practitioner employed by
ACH. She suggested that Ellis breathe into a bag, believing
he was having a panic attack. At 4:08 a.m., jail personnel
called Scherling back and reported that breathing into the bag
was not helping and that Ellis was now complaining of chest
pain. Scherling instructed jail personnel to take Ellis to the
hospital. At the Saunders Medical Center, Ellis was treated
for a heart attack, but he died at 6:20 a.m. from a bilateral
pulmonary embolism.
   Ewers, who is Ellis’ sister, filed suit, alleging that Ellis’
death and associated damages resulted from the negligence of
Reeves and Scherling. Ewers sought damages from Reeves and
Scherling in their individual capacities and from ACH. In part,
Ewers specifically averred that as a result of the negligence of
Appellees, Ellis experienced damages and injuries, including
chest pain, trouble breathing, and nightmares.
                      Summary Judgment
   On January 6, 2017, Appellees filed a motion for summary
judgment. The district court conducted a hearing and received
evidence. For purposes of the appeal of the summary judgment,
only the evidence relating to Reeves’ conduct is relevant.
   Victoria Halstead, a registered nurse, reviewed the autopsy
report and medical records for Ellis and depositions by Reeves,
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           Nebraska Supreme Court A dvance Sheets
                   298 Nebraska R eports
                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

Scherling, the sheriff, and jail personnel. She explained in
a deposition that any person who complains of chest pain
or shortness of breath requires a face-to-face assessment.
Therefore, she opined that Reeves should have conducted an
in-person assessment of Ellis’ condition on June 22, 2010.
Further, in Halstead’s opinion, Ellis should have been taken to
a hospital to be examined by a physician that day.
    Halstead conceded that other than the “kite” form that Ellis
filled out on June 22, 2010, he made no further reports of chest
pain, shortness of breath, or other issues on June 22, 23, or 24.
She stated that she could not predict whether the results of a
complete medical assessment on June 22 would have yielded
normal or abnormal results, but she suspected that the results
would have been abnormal. But she testified that she did not
have an opinion as to what a medical “workup” on June 22
would have shown.
    The district court received the deposition testimony of Joyce
Black, a registered nurse with a Ph.D. in nursing who both par-
ties used as an expert witness. Ewers’ counsel conducted direct
examination for Black’s deposition, and Appellees’ counsel
cross-examined her.
    Black testified that she instructs graduate students on the
subject of pulmonary embolism. To prepare for her testi-
mony, Black reviewed records from the Saunders County jail;
records of Ellis’ emergency room visits, autopsy and forensic
toxicology report, and death certificate; narratives of events
from jail personnel; and the Nebraska State Patrol investiga-
tive report.
    Black explained that a blood clot, or embolus, can form,
perhaps in the leg, and that a piece of the clot can break
off and travel through the body until it becomes lodged in a
lung (a pulmonary embolism). As a result, the clot will then
block the flow of blood and oxygen to the tissue beyond
the clot, and that tissue stops functioning. She testified that
“[e]arly diagnosis is better in all cases because you want to
stop the extension and additional clots from forming, and
you do that with anti-coagulation.” But Black also stated
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                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

that even with early treatment, not all pulmonary embolisms
are survivable.
   Black further explained that the body mounts an inflamma-
tory response to a pulmonary embolism. According to Black,
the pain is “exquisite” or “excruciating” and does not go away.
Black testified that the pain continues during the entire inflam-
matory response, which lasts about 72 hours. Black testified
that in addition to excruciating pain, someone dying of a pul-
monary embolism would experience the sensation of difficulty
breathing and possibly the feeling of impending doom. She
testified that once blood flow is completely blocked, a patient
would remain conscious for less than 1 minute.
   Black testified that surgeons would remove saddle emboli,
the type that Ellis suffered, only when such emboli are posi-
tioned a certain way and that even then, there was a risk
that the clot would break during surgery and kill the patient.
She described having a patient’s family say goodbye prior to
surgery because “that’s how uniformly fatal that particular
embolus is.”
   Based on Ellis’ history; his complaint on June 22, 2010;
and the absence of additional complaints until June 25, Black
offered her opinion that there was no pulmonary embolus on
June 22. Black testified with “reasonable medical certainty”
that an examination on June 22 would not have shown that
Ellis was having a medical issue or a pulmonary embolism.
She stated that if Ellis had experienced a pulmonary embo-
lism on June 22, his condition would have worsened on June
22, 23, and 24. According to Black, based on Ellis’ history of
anxiety, it was not problematic for Reeves not to examine him
on June 22.
   Upon examination by Ewers’ counsel, Black agreed that if,
hypothetically, Ellis had a pulmonary embolism on June 22,
2010, then Reeves, hypothetically, should have examined him.
She also agreed that if Ellis had a pulmonary embolism on
June 22 and had been treated for it, his chances of recovery
would have been higher. Black emphasized, however, that in
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                   298 Nebraska R eports
                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

her opinion, Ellis did not suffer a pulmonary embolism on
June 22.
   The district court granted the motion for summary judg-
ment, finding no material issue of fact as to causation. It
found that there was no expert testimony establishing a causal
link between the acts of Reeves and Scherling and injuries or
damages suffered by Ellis or Ewers. Specifically, the district
court discerned no evidence that Ellis suffered a pulmonary
embolism on June 22, 2010, or that an examination of Ellis
on June 22 would have identified the presence of a pulmonary
embolism on that date. It expressly rejected Ewers’ argument
that Black’s response to a hypothetical question, that early
detection of a pulmonary embolism on June 22 could have
helped Ellis if he suffered from such condition on that day,
was sufficient to show causation, because Black did not sub-
scribe to the version of the facts presented in the hypotheti-
cal question.
   Ewers now appeals the order granting summary judgment.
                            Discovery
   In addition to challenging the summary judgment, Ewers
assigns errors pertaining to the discovery process and Appellees’
alleged failure to timely and properly respond to requests for
admission, requests for production, and interrogatories.
   On April 8, 2014, Ewers filed a motion to compel discovery,
which alleged that Appellees had provided “[i]mproper and/
or inadequate” responses to certain requests for admission,
requests for production, and interrogatories, purportedly “Sent
11-20-13.”
   On April 21, 2014, the district court sustained the motion
and gave Appellees another opportunity to answer Ewers’ “11-
20-13” discovery. Ewers claims that the district court allowed
Appellees 2 weeks to provide its answers.
   On July 16, 2014, Ewers filed a motion to deem requests for
admission admitted and to dismiss Appellees’ answer, regard-
ing “11-20-13” discovery. Ewers contended that Appellees
had not provided the answers required by the district court’s
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           Nebraska Supreme Court A dvance Sheets
                   298 Nebraska R eports
                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

previous order. On August 18, 2014, the district court ordered
that supplemental answers and admissions be provided by
August 25 or be deemed admitted.
   On September 16, 2014, Ewers filed an amended motion
to deem requests for admission admitted and to dismiss
Appellees’ answers, regarding the discovery for ACH, Reeves,
and Scherling on November 13, 2013, and March 27 and April
9, 2014. She alleged that Appellees failed to comply with the
district court’s previous order because they had not submitted
their responses to the requests for admission by August 25,
2014, and alleged such responses were improper. Further, she
alleged that Appellees had provided untimely and insufficient
responses to other requests for admission and no response to
her other requests for documents and interrogatories. Following
a hearing on September 16, 2014, the district court found that
there was not sufficient evidence to ascertain the degree to
which the requests were incomplete or had been or not been
complied with. Given this, the district court made no ruling on
the timeliness of the admissions.
   On September 25, 2014, Ewers filed a motion to deem
requests for admission admitted and to dismiss Appellees’
answer, regarding the same discovery as the previous motion.
Following a hearing, Ewers filed an “Explanation of Discovery
Responses From Defendants,” which alleged that Appellees
had failed to comply with previous court orders to provide
discovery responses and Black’s expert report, or allow Ewers
to depose Jessica Young, an attorney for ACH. On October 27,
the district court’s pretrial order stated, “Rule 37 request to be
responded to within 30 days. Court will address the issue of
imposition of costs as the result of the delay in discovery at
time of trial.”
   On December 5, 2014, Ewers filed a motion to deem
requests for admission admitted and to dismiss defendant’s
answer, again regarding the same discovery as the previous
motion. On December 17, the district court noted that the
record had become “voluminous and confusing” and that “it
is difficult, if not impossible for the court to ascertain what
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                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

has and has not been requested and what has and what has not
been appropriately answered.” It ordered the parties to submit
all discovery disputes to the district court in a specific outline
format and to meet and discuss the outline in advance of the
next hearing. The district court attached an outline form for
the parties to fill in and provided explicit instructions on how
to do so.
   On February 11, 2015, Ewers filed a motion to compel “B”
discovery or, in the alternative, dismissal of Appellees’ answer,
which concerned Appellees’ responses to requests for admis-
sion and interrogatories. A hearing was held on February 23.
Ewers used a paragraph format to summarize the litigation and
did not comply with the outline format required by the district
court’s previous order, claiming at the hearing that the issues
were too complex for an outline format. On February 25, the
district court ruled that all discovery matters not presented in
the format it had ordered were waived. However, the district
court did order that all interrogatories must be signed under
oath within 10 days.
   Appellees subsequently submitted responses to interrogato-
ries signed under oath by Sherri Miller, not Young, who had
previously signed the responses, but not under oath.
   On April 3, 2015, Ewers filed an “Amended Motion to
Compel ‘B’ Discovery or . . . Dismissal of Defendants’
Answers and/or . . . Hold Defendants in Contempt and/or . . .
Disqualify Defendants’ Counsel for a Conflict of Interests.”
The motion stated that Appellees’ counsel had committed
repeated and intentional violations of court and ethical rules.
On April 14, the district court denied all relief requested by
Ewers’ motion.
   On November 30, 2016, following the sua sponte recusal of
the initial judge, Ewers filed a motion to dismiss Appellees’
answers or, in the alternative, to deem requests for admission
admitted. The motion alleged that Appellees had repeatedly
refused to answer discovery requests, comply with orders of
the court regarding discovery, and timely answer requests for
admission. On December 30, with a new judge presiding, the
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           Nebraska Supreme Court A dvance Sheets
                   298 Nebraska R eports
                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

district court overruled the motion, finding the district court’s
previous orders were the law of the case. Regarding discovery
documents now addressed on appeal, it observed that Ewers
had refused to use the outline format ordered by the previous
judge. The district court further noted that all prior motions to
deem requests for admission admitted or dismiss Appellees’
answers were denied by the district court and that Ewers
had failed to show a fundamental change or that the earlier
orders were erroneous. In addition to denying Ewers’ latest
motion, the district court ruled that it was frivolous and granted
Appellees attorney fees of $500.
   On January 27, 2017, the district court made a journal entry
memorializing that Ewers had been given 10 days to pay
the $500 attorney fees pursuant to the December 30, 2016,
order.
   Ewers now appeals the order dated December 30, 2016, and
the journal entry dated January 27, 2017.
                  ASSIGNMENTS OF ERROR
   Ewers assigns, renumbered and restated, that the district
court erred in (1) failing to correctly apply the law by not
deeming the request for admission as admitted, failing to
impose Neb. Ct. R. Disc. § 6-337 sanctions on Appellees for
failure to follow Nebraska Court Rules of Discovery in Civil
Cases, such as dismissing the answer of Appellees; (2) failing
to find there is a genuine issue of material fact in this case
and granting Appellees’ motion for summary judgment; and
(3) failing to find that Reeves was also the proximate cause of
Ellis’ pain and suffering.
                   STANDARD OF REVIEW
   [1,2] Decisions regarding discovery are directed to the dis-
cretion of the trial court, and will be upheld in the absence of
an abuse of discretion. Moreno v. City of Gering, 293 Neb.
320, 878 N.W.2d 529 (2016). The party asserting error in a
discovery ruling bears the burden of showing that the ruling
was an abuse of discretion. Id.
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                  EWERS v. SAUNDERS COUNTY
                      Cite as 298 Neb. 944

   [3] In reviewing a summary judgment, an appellate court
views the evidence in the light most favorable to the party
against whom the judgment was granted and gives that party
the benefit of all reasonable inferences deducible from the
evidence. White v. Busboom, 297 Neb. 717, 901 N.W.2d
294 (2017).

                          ANALYSIS
                          Discovery
   Over the course of the litigation, Ewers filed several
motions to compel discovery, to impose sanctions, to deem
her requests for admission admitted, and to dismiss Appellees’
answers, all of which the district court denied. Now on appeal,
Ewers claims that the district court erroneously applied the
law by not deeming her requests for admission admitted
and by declining to impose § 6-337 sanctions on Appellees
for failure to follow Nebraska Court Rules of Discovery in
Civil Cases.
   [4,5] Ewers correctly notes that the Nebraska Supreme
Court rules relating to discovery provide that a party may
serve on another party written requests for admission and that
unless answered, objected to within 30 days after service, or
requested to be withdrawn, the requests are deemed admitted.
See Neb. Ct. R. Disc. § 6-336. We have held that a party’s
failure to make a timely and appropriate response to a request
for admission constitutes an admission of the subject mat-
ter of the request, which matter is conclusively established
unless, on motion, the court permits withdrawal of the admis-
sion. Tymar v. Two Men and a Truck, 282 Neb. 692, 805
N.W.2d 648 (2011). We have recognized that § 6-336 is self-
enforcing, without the necessity of judicial action to effect an
admission which results from a party’s failure to answer or
object to a request for admission. Tymar v. Two Men and a
Truck, supra.
   [6,7] We have noted, however, that § 6-336 is not self-
executing. Tymar v. Two Men and a Truck, supra. Thus, a party
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                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

that seeks to claim another party’s admission, as a result of
that party’s failure to respond properly to a request for admis-
sion, must prove service of the request for admission and the
served party’s failure to answer or object to the request and
must also offer the request for admission as evidence. Id. If the
necessary foundational requirements are met and no motion is
sustained to withdraw an admission, a trial court is obligated
to give effect to the provisions of § 6-336 which require that
the matter be deemed admitted. Tymar v. Two Men and a
Truck, supra.
   In her reply brief, Ewers points to several exhibits and
argues that the record reflects compliance with the prereq-
uisites to deem requests for admission admitted pursuant to
§ 6-336. One exhibit cited is an affidavit from counsel for
Ewers verifying the accuracy of several exhibits and purport-
ing to verify delivery of discovery. The affidavit states in part,
“Exhibit 73, Delivery to ACH, 11/20/13.” Exhibit 73 itself
was not attached to the affidavit. Exhibit 73, along with other
exhibits in the record referenced by Ewers, contains the front
page of Ewers’ request for admission and the responses from
ACH. These exhibits do not contain, as required, a complete
copy of the request for admission or a copy of any certificate
of service (notice of service) that would have been completed
in conjunction with the admissions. As the district court spe-
cifically pointed out, this lack of evidence prevented it from
ruling on Ewers’ motions, and it ultimately resulted in the
district court’s requesting that Ewers set forth her requested
discovery and any alleged failure to respond in a format that
the district court could use in its determination. Ewers, how-
ever, failed to comply with the order. Consequently, we find no
abuse of discretion by the district court in declining to impose
sanctions or to deem Ewers’ requests for admission admitted
by Appellees.
                   Summary Judgment
  Ewers assigns that the district court erred in granting
Appellees’ motion for summary judgment. As the parties
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                  EWERS v. SAUNDERS COUNTY
                      Cite as 298 Neb. 944

moving for summary judgment, Appellees had the burden
to show that no genuine issue of material fact exists and to
produce sufficient evidence to demonstrate that they were
entitled to judgment as a matter of law. See Barnes v. American
Standard Ins. Co. of Wis., 297 Neb. 331, 900 N.W.2d 22
(2017). In reviewing a summary judgment, we view the evi-
dence in the light most favorable to the party against whom
the judgment was granted and give that party the benefit of all
reasonable inferences deducible from the evidence. White v.
Busboom, 297 Neb. 717, 901 N.W.2d 294 (2017).
   [8,9] Here, the substantive issue is whether there is a
genuine issue of material fact that Appellees committed medi-
cal malpractice when treating Ellis at the jail. Currently, in
Nebraska, in a malpractice action involving professional negli-
gence, the burden of proof is upon the plaintiff to demonstrate
the generally recognized medical standard of care, that there
was a deviation from that standard by the defendant, and that
the deviation was a proximate cause of the plaintiff’s alleged
injuries. Cohan v. Medical Imaging Consultants, 297 Neb. 111,
900 N.W.2d 732 (2017). In the medical malpractice context,
the element of proximate causation requires proof that the
physician’s deviation from the standard of care caused or con-
tributed to the injury or damage to the plaintiff. Id.
   Ewers claims that Halstead’s expert opinion, that a medi-
cal examination should occur when someone is complaining
of chest pain or shortness of breath, is sufficient proof of
the standard of care. Therefore, Ewers contends that Reeves
should have examined Ellis in person on June 22, 2010, and
that without such an examination or admission to the hospital
on June 22, a breach of the standard of care occurred. On our
review, we give Ewers the benefit of this inference that the
standard of care had been breached by Appellees. See White v.
Busboom, supra.
   [10-12] However, a defendant’s negligence is not action-
able unless it is a proximate cause of the plaintiff’s injuries
or is a cause that proximately contributed to them. Hamilton
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                   EWERS v. SAUNDERS COUNTY
                       Cite as 298 Neb. 944

v. Bares, 267 Neb. 816, 678 N.W.2d 74 (2004). A proximate
cause is a cause that produces a result in a natural and con-
tinuous sequence and without which the result would not have
occurred. Radiology Servs. v. Hall, 279 Neb. 553, 780 N.W.2d
17 (2010). A defendant’s conduct is a proximate cause of an
event if the event would not have occurred but for that con-
duct, but it is not a proximate cause if the event would have
occurred without that conduct. Worth v. Kolbeck, 273 Neb.
163, 728 N.W.2d 282 (2007). Appellees assert that there was
no expert testimony in this record, from anyone qualified to
render a medical opinion, that the breach of the standard of
care by Reeves on June 22, 2010, was causally connected to
the fatal pulmonary embolism suffered by Ellis on June 25.
We agree.
   To support her position, Ewers points to Halstead’s testi-
mony. Although Halstead opined that Reeves breached the
standard of care, she did not causally connect Reeves’ fail-
ure to examine Ellis in person on June 22, 2010, to his fatal
pulmonary embolism on June 25, nor did she opine that
such an examination would have resulted in a different out-
come. In other words, Halstead offered no testimony show-
ing causation.
   Ewers also relies on Black’s statement that “[e]arly diagno-
sis is better in all cases because you want to stop the exten-
sion and additional clots from forming, and you do that with
anti-coagulation.” She argues that this evidence translates into
causation pursuant to Richardson v. Children’s Hosp., 280 Neb.
396, 787 N.W.2d 235 (2010). In Richardson, we held that an
expert’s opinion that the outcome would have been different
had a patient, who died of necrotizing hemorrhagic pancreati-
tis, earlier received intravenous fluids was sufficiently akin to
a degree of medical certainty and was sufficient to establish
causation for purposes of a medical malpractice case. In so
holding, we reiterated the principle that expert opinion is to be
judged in view of the entirety of the expert’s opinion and is not
validated or invalidated solely on the basis of the presence or
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lack of the magic words “‘reasonable medical certainty.’” Id.
at 405, 787 N.W.2d at 243.
   In countering, Appellees note that Black’s statement that
“[e]arly diagnosis is better in all cases . . .” does not prove
causation because it was a general medical opinion taken out
of context. Appellees further assert that Ewers is misguided
in relying on Black’s hypothetical opinion that if Ellis had
been examined on June 22, 2010, and if a nonfatal pulmo-
nary embolus had been discovered on that date, his chances
of recovery would have been higher. As Black emphasized in
her testimony, the facts in Ellis’ case were different from the
facts posed in the hypothetical question. In addition, Black
opined that Ellis did not experience a pulmonary embolus on
June 22, because he did not complain of any pain from June
22 to 25 and had himself advised medical staff of his history
of anxiety-related chest pain. Black stated that if Ewers had
actually suffered a pulmonary embolus on June 22, his con-
dition would have worsened from that point forward to June
25. And the facts here show that after reporting his symp-
toms on June 22, Ellis did not complain of pain again until
June 25.
   [13] Expert testimony is almost always required to prove
proximate causation. Thone v. Regional West Med. Ctr., 275
Neb. 238, 745 N.W.2d 898 (2008). In the absence of expert
testimony on causation, the finder of fact would be left to
resort to guess, speculation, or conjecture as to the issue. See
Snyder v. Contemporary Obstetrics & Gyn., 258 Neb. 643, 605
N.W.2d 782 (2000) (burden of proving cause of action is not
sustained by evidence from which jury can arrive at its conclu-
sions only by guess, speculation, conjecture, or choice of pos-
sibilities; there must be something more which would lead a
reasoning mind to one conclusion rather than to another). Our
previous cases discussing the sufficiency of expert opinions
in a medical malpractice case have held that expert medical
testimony based on “could,” “may,” or “possibly” lacks the
definiteness required to meet the claimant’s burden to prove
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                   EWERS v. SAUNDERS COUNTY
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causation. See, e.g., Paulsen v. State, 249 Neb. 112, 541
N.W.2d 636 (1996). As we have observed:
      Our well-known preference for the use of the phrases
      “reasonable degree of medical certainty” or “reasonable
      degree of probability” is an indication to courts and par-
      ties of the necessity that the medical expert opinion must
      be stated in terms that the trier of fact is not required to
      guess or speculate at the cause of the injury.
Id. at 121, 541 N.W.2d at 643. Here, Black’s answer to a
hypothetical question assuming facts not present does not rise
to the level of certainty required and would invite the trier of
fact to speculate. Therefore, Black’s testimony on early diag-
nosis being beneficial did not establish causation as argued by
Ewers. But whether Black, a registered nurse, could render an
opinion on medical causation was not raised as an issue in this
case, and we make no comment thereon.
   Ewers further claims that Appellees withheld an email from
Black which may have affected her opinions. However, Ewers
took Black’s deposition, apparently did not provide her the
email during the deposition, but ultimately named Black as her
expert even though Black had not seen the email. Under these
circumstances, Ewers had the opportunity to question Black
about the email and could have supplemented her deposition or
other discovery. Therefore, this argument has no merit.
   In sum, even giving Ewers the benefit of every reason-
able inference, without any expert testimony showing that
Appellees’ actions were the proximate cause of the fatal pul-
monary embolism suffered by Ellis on June 25, 2010, or were
a cause that proximately contributed to it, the district court
correctly found that there was no genuine issue of material fact
as to causation and that Appellees were entitled to judgment as
a matter of law.
   Lastly, Ewers claims that the district court erred in failing
to find that Reeves was also the proximate cause of Ellis’
pain and suffering. Ewers argues that Black’s description of
the pain inflicted by an embolus traveling through a patient’s
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                  EWERS v. SAUNDERS COUNTY
                      Cite as 298 Neb. 944

lung established proximate cause. However, this argument
also fails due to the absence of expert testimony establishing a
causal connection between Reeve’s conduct on June 22, 2010,
and the pulmonary emboli on June 25. Evidence of the pain
Ellis suffered on June 25 would apply to damages, not causa-
tion. Therefore, this assignment of error is without merit.
                         CONCLUSION
   For the reasons stated above, we conclude that the district
court did not abuse its discretion in declining to deem Ewers’
requests for admission admitted, to dismiss Appellees’ answers
to discovery, and to sanction Appellees. Further, finding no
genuine issue of material fact as to causation, we conclude that
the district court did not err in granting Appellees’ motion for
summary judgment. We affirm.
                                                     A ffirmed.
   Wright, J., not participating.
