Blunt Abdominal Trauma - PDF

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					          PSA Wagga Wagga
          2008



         Investigation of

         Blunt
         Abdominal
         Trauma
          Carolyn Vasey




Good morning. My name is Carolyn Vasey and I am a new SET trainee in
General Surgery. Hopefully those concerned about the future of surgery in
rural areas can be rest-assured that there are good quality young trainees out
there who are keen to be taught the range of knowledge and skills needed to
be a rural general surgeon. I grew up in Shepparton and I’ve noticed a number
of the Shepparton surgeons here today, in fact, he probably wont remember
this, but Roly Hunt ‘saved my life’ when he took my appendix out when I was
12!


Anyway, I thought this year I would present a summary of some of what I
learnt doing the Trauma job at Royal Melbourne Hospital, in particular I’m
going to look at the investigation and initial management of blunt abdominal
trauma because I thought it would be most useful for rural general surgeons.




                                                                                 1
        Blunt Abdominal Trauma (BAT)
        • Common in rural setting
            – MVA
            – farm accidents
            – falls

        • Initial management critical
           – ? local management v              transfer out




Detecting closed abdominal injuries is often challenging, especially if it
presents with a concurrent head injury or decreased GCS for any other
reason. There is a high prevelance of BAT in the rural setting with a high
number of open road car accidents (usually at high speed), farm accidents
involving heavy machinary, crush injuries, and falls.


The intial work up of these patients brought into regional hosptial Emergency
Departments is critical for the surgeons decision making and the outcome for
the patient. The right decision made quickly can save lives.


To assist in this rapid initial assessment, it is important to know which type of
imaging to use when. It is common with closed abdominal injury to have a
wide spectrum of injury severity, ranging from no injury at all despite a high-
risk mechanism to quite significant injury in what would seem realtively “minor”
trauma.




                                                                                    2
        Why rely on Imaging?
        •   Physical examination is unreliable
                     – Low sensitivity
                     –   GCS, distracting injuries
                     – Drugs, alcohol, head, spinal cord injuries
                     – Little examination findings in a large prospective observational study
                           »   Salim et al.,Arch Surg 2006;141:468-75
                     – One study of 157 patients with abdominal tenderness; only 40 (25.5%) had
                       intraabdominal injury on CT; Only 7 (20%) of those with seat belt sign had
                       confirmed intraabdominal injuries
                           »   Miller et al., J Trauma 2003;54:52-60




        • Need quick, decisive and appropriate Ix
                     – Facilitates definitive Mx and improves outcome
                     – Facilitates selection for non-operative Mx
                     – Fewer non-therapeutic laparotomies and missed injuries


        • Missed abdominal injuries
                     – Frequent cause of preventable morbidity and trauma deaths
                     – In one autopsy study 43% of abdominal injuries were missed during
                       primary ED screening
                          » Hodgson et al, Canadian J Surgery 2000;43(2):130-6




So… why do we need to rely so heavily on imaging to determine wheather or
not a patient needs to procede to laparotomy? Primarily because the physical
examination is often unreliable for a number of reasons; patients may have
distracting injuries, can uncoperative or obtunded, and often there is just not
much to find. If elicited, tenderness is not a particularly helpful finding as a
number of studies have shown no correlation between tenderness and
underlying injury. As such, confirming the presence of injury relies largely on
diagnositic adjuncts.


Negative imaging can also be reassuring to the surgeon in their decision to
manage some injuries conservatively, and has been shown to decrease the
“negative laparotomy” rate. Appropriate imaging helps to prevent significant,
life-threatening injuries from being missed (which, as Ian Farmer told us, can
be a problem rural ED where their may be inexperienced junior staff on
overnight, lack of trauma protocols, and problems accessing the right support
quickly if required).


At this point I should note that if a patient has a completely normal examination
– in particular, the patient has remained hameodynamically stable throughout
and the abdomen is soft and non-tender – there is a recognised role for serial
abdominal examinations repeated regularly in the first 24/24. Serial
examinations should also be performed if any injury found on initial imaging
(eg splenic laceration) has been managed conservatively.
                                                                                                    3
        Imaging Modalities



        1. FAST (Focused Abdominal Sonography for
            Trauma)

        2. DPL (Diagnostic Peritoneal Lavage)
        3. CT (Computed Tomographic Scanning)

                  Plain CXR & PXR




The three types of imaging I will cover today are the FAST, DLP, and CT scan.
A lot of data exists regarding their sensitivity, specificity, and overall
usefullness and I have attempted to summarise much of this to make it
relevate to the rural Australian hospital setting, where then may not always be
immediate access to the newer thin-slice, high resolution CT scanners.


Before going into detail about these modalities, I should make it clear than
none of these take the place of a plain CXR and PXR, which should be
routinely done all trauma patients. Although not particularly useful in imaging
the abdomen, these films can highlight rib or pelvic fractures which should
raise the possiblity of underlying intra-abdominal injury. It is also good to know
about the possibliity of a big retro-peritoneal haematoma caused by pelvic
fractures before thinking about putting a needle in the abdomen when doing a
DPL!




                                                                                     4
        Which modality when?

        • Access
           – equipment
           – time of day
           – staff avalibility eg radiology, laboratory

        • Patient Suitability
           – unstable pts NOT safe for CT

        • Clinical Suspicion
           – likely injury to hollow organ            DPL
             most useful



So when considering which imaging modality to use when it is obviously
important to consider which modality is avaliable, including factors that may
influence the amount of time it takes to get it organised (for example getting
the radiology department up and ready to go in the middle of the night might
make CT a little less accessible!)


CT scanning is also contra-indicated in the haemodynamically unstable or
shocked patient, including those who transiently respond to resusitation.
Patients are separated from the treating trauma team and often “crash” on the
CT table – as such, it is a very dangerous place for the unstable, undiagnosed
patient.


One’s clinical suspicision can also determine which investigation is used as
first line  for example DPL is very good at picking up mesenteric tears or
hollow organ perforations, but a lot less useful if concerned about pelvic
fractures and the bleeding associated with it.




                                                                                 5
       FAST
       • Effective and sensitive in detecting free peritoneal
         fluid
                 Several large studies of haemodynamically unstable pts
          found:
               • Sensitivity 79 – 100%
               • Specificity 95.6 – 100%
               • Accuracy comparable to that of DPL or CT
                       » Healy et al, J Trauma 1996;40:875-85
                       » Rozycki etal, Ann Surg 1998;228:557-67


       • Well established role in the UNSTABLE pt with
         BAT

       • Less reliable in the STABLE pt
                   – U/S is only reliable for detecting free intraabdominal
                     fluid
                        » Poletti et al., Radiology. 2003;227(suppl 1):95-103
             Often lack of haemoperitoneum in stable pts




The FAST scan has emerged as a useful diagnostic test in the evaluation of
BAT. It is an ultrasound done in ED, often by the surgeon, which takes 3 or 4
mins to complete, and can be performed concurrently with resuscitaiton. It’s
primary aim is to detect free fluid in the abdomen. Its role in the
haemodynamically unstable patient is well established, where it is a quick,
non-invasive way of detecting free fluid. It is not used in the haemodynamically
stable where serial examinations or CT should be performed.




                                                                                   6
        FAST
        • Rapid, portable, non-invasive
                  – Can be done by surgeon
                      » Smith SR, Arch Surg. 1998; 133:530-536
                      » Buzzaz GR, J Trauma, 1998; 44:604-608
                  – Avoids transporting unstable patient to CT



        • No radiation risk


        • Low cost


        • ? Easier access in rural areas


The FAST scan is highly portable and can easily be repeated at any stage
during the resuscitation process. There a number of papers that show the
surgeon-performed ultrasound can be learned without a signficant learning
curve and when compared with radiologists or ED physicians, surgeons were
just as good at doing the scan! This type of scan also avoids the problem of
transporting the shocked patient to the CT scanner.


Compared with the significant radiation doses involved with a CT, the US has
no radiation risk, particularly important in pregnant women.


Given my talk at this conference last year was on US guided TAP blocks,
some of the audience may suspect I’m working for GE on the side, but I can
reassure you I’m not – I just think that given the low cost, portability, and the
fact that these skills can be learnt relatively quickly, there is a signifcant role
for US based imaging in rural areas, as was discussed yesterday and today. I
worked for Mr Peter Milne (a vascular surgeon at RMH) earlier in the year who
flew me down to Bairnsdale to do a monthly clinic down there. My job was to
pack up his little US machine and carry it round so his vascular patients could
present, be worked up, and booked for surgery all in the same sitting in the
same tiny little room. When it came to the end of the day we unplugged the
portable machine, packed it up, and flew it home again! It was quiet impressive
really and very handy.


                                                                                      7
        Disadvantages
        • Minimum ~200ml free fluid

        • Hollow visceral injury

        • Solid organ injury
                CT follow up if –ve

        • Overall:
                       specificity: 98-100%
                       sensitivity: 73-88%
                       accuracy: 96-98%




The FAST does have some significant disadvantages however. For free fluid
to be detected, in the hands of most operators, there needs to be at least
200mls. Therefore injuries not assosicated with haemoperitonium can be
missed by the FAST.


Ultrasound is also unreliable in picking up hollow organ injury, where there
may be very little free fluid at all.


In addition, FAST cannot reliably grade solid organ injury, therefore in the
haemodynamically stable patient, a follow-up CT scan should be obtained if
non-operative management of any injury is contemplated.




                                                                               8
       What is the role for DPL?
       • First described in 1965
       • Shown to be highly accurate for
         intraperitoneal blood
                 – Sensitivity 95%, Specificity 99%
                     » Nagy et al., Experience with over 2500 diagnostic peritoneal
                       lavages Injury 1998;29:65-71

       • Reported to be more sensitive than
         CT or U/S for detection of hollow
         viscus injuries
                     » Hoff et al., J Trauma 2002; 53:602-15

       • Now regarded by many authors as
         obsolete
                 – FAST has replaced DPL as investigation of choice
                   in haemodynamically unstable patients




The Diagnostic Peritoneal Lavage is an old technique that was initally
discribed in 1965 and historically was the standard of care. The technique
again can be done in the trauma setting without transporting the patient, and
has been shown to be highly accurate for detecting intraperitoneal blood.
Compared to both CT and US it has a higher rate for detecting injuries to
bowel. However the technique is now rarely used, with FAST replacing its use
in haemodynamically unstable patients.




                                                                                      9
        Criteria for positive DPL

        • DPL positive if:

               • Gross Blood > 10ml
               • Red cells > 100,000/mm3
               • White cells > 500/mm3
               • Amylase > 175
               • GI contents
               • Bacteria on Gram stain




The DPL involves introducing a small amont of levage fluid into to the
abdoment and then taking off that fluid and inspecting it and getting a formal
analysis to detect blood, GI contents or the like.


Studies looking at the sensitivity of visual inspection of the levage fluid
compared with lab testing show poor sensitivity of visual inspection of the fluid,
especially in the equivocal range. Which means that this actually takes a little
longer that you would think, given that there is a delay in getting the sample to
the lab, looked at, and reported before any significant decision can be made.




                                                                                     10
        DPL
        • Disadvantages
                  – Invasive
                  – Small risk visceral injury (0.6%)
                  – Lavage fluid may interfere with interpretation of
                    subsequent imaging
                  – Not all patients with haemoperitoneum require
                    laparotomy
                      » May lead to high non-therapeutic laparotomy
                        rate – up to 36%
                             Eastern Association for the Surgery of Trauma 2003
                             Bain et al., Injury 1998;29:65-71

        • Role as second line investigation
           – adjunct to FAST




The disadvantages with DPL are that it is an invasive procedure, with a very
small risk to underlying organs.


Also, once fluid has been deliberatetly introduced into the abdomen it can
cloud futher assessment.


There are no absolutes with DPL and results should always be interpreted in
the context of overall clinical picture – for example a positive DPL does not
necessarily mandate immediate laparotomy in the haemodynamically stable
patient.


Really the role for DPL these days is as an adjuct to FAST    if fluid is found
on US then DPL can be a useful way of figuring out what it is and where it’s
come from.




                                                                                  11
       CT Scan
       •   Imaging modality of choice for haemodynamically stable patients

       •   High specificity for hepatic, splenic and renal injuries
                • Sensitivity 92 - 97.6%
                • Specificity up to 98.7%

       •   Assess retroperitoneum
       •   Detect injuries to diaphragm

       •   With newer 64 slice high definition CT
            – Better ability to grade severity of injury
                     – Select those for non-operative management
            – Better ability to detect contrast extravasation
                     – Which predicts need for surgery or angioembolisation




CT scanning is fantastic in the right setting – patients must be
haemodynamically stable and co-operative. If not it is contraindicated.


The CT scan is very good at assessing the retroperitonium and diaphragm. It
is also much better at grading the severity of injury and can quickly detect
extravasation of contrast which is very helpful in identifying the point of
bleeding and can determine if the bleeding needs operative mangament or
angioembolisation instead.




                                                                               12
       CT scan
       • Disadvantages
                  – Less sensitive in identifying hollow visceral injuries

                  – Need to transfer pt; separation of pt & trauma team

                  – Pt cooperative or sedated

                  – Higher radiation exposure

                  – Healthcare costs

       • Free fluid on CT without solid organ injury?
                  – Awake patients    serial examination
                  – Neurologically compromised     DPL ?nature of fluid
                                                           (bld v GI content)
                       »   Rodriguez et al. Isolated free fluid on CT scan in blunt abdominal trauma: a systematic review
                           of incidence and management. J Trauma 2002;53:79-85




CT scanning is renowend to be quiet poor at picking up injuries to hollow
viscera, as I’ve said needs the right type of patient, and exposes patients to a
significant level of radiation. One study done in the US in 1997 demonstrated a
projected cost saving of $41,000USD when FAST US were done in 300
patients rather than routinely CT scanning these patients.


The other problem with abdominal CT is what to do with those who have a
small amount of free fluid but no obvious solid organ injury in these patients,
provided they are awake and alert, conservative management with serial
abdominal examinations is best, but in those who are neurologically
compromised DPL should be considered to clarify the nature of the fluid.




                                                                                                                            13
        Inter-hospital Trauma Transfer
        • Ring Trauma Registrar/Consultant on
          call (24/7)

        • Verbal report of Ix & operative findings

        • Written op report very useful

        • Imaging (inc spinal clearance)

        • Follow-Up


Just before I finish I thought I would touch on the issue of transferring trauma
patients to the big smoke... I am very junior and have not had any experience
in transferring unstable trauma patients from rural areas, but I have been on
the receiving end of a transfer down to RMH on a number of occasions. These
are my basic suggestions to improve the communication between the rural
surgical team and the tertiary hospital.


It is very helpful to have a verbal handover of how the patient presented, what
Ix they have had and what the operative findings were. I know it must often
feel like there are many different Registrars and you can never seem to speak
to the same one twice, do try and phone ahead and let them know what you’ve
found and what you are thinking. Hopefully the Registrar wont speak loudly
and slowly to you just because you’re from the country!


Sending a copy of the written operation report is invaluable, especially if they
have had a damage control laparotomy and packs remain insitu.


Also sending any imaging with the patient, in particular written documentation
from a consultant radiologist who may have cleared the spine is very useful
(this is can save the patient being unnecessarily re-scanned in Melbourne as
many of the radiologists I have come across are not prepared to clear the
spine on the basis of an outside films). Frustratingly there is not yet a universal
imaging software program which means technical difficulties often arise. If the
films have been reported, a printed copy of the report is very helpful because        14
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