Trauma Flashcards
Discuss threshold of foetal viability
Estimated gestationl age of 24-26 weeks or an estimated foetal weight of <500g
Only viable foetus should be monitored as no obsetric intervention will alter the outcome with a previable fetus
Discuss anatomical changes in pregnancy
The uterus remains an intrapelvic organ until approximatly the 12th week of gestation. It reaches the umbilicus at 20 weeks and the costal margins at 34-36 weeks.
The diagphragm progressively rises in pregnacny with compensatory flaring of the ribs which may predispose to pneumothorax and a faster progression to tension. - A thoracostomy done in the third trimester should be placed 2 rib spaces higher to account for this shift
The abdominal vicera are pushed upwards by the elnarged uterus and can alter the location of percieved pina. The gravid uterus itself tends to protect the abdominal organs but the bowels are at greater risk of injury
Discuss physiological changes in pregnancy
CVS - a major contributor to maternal hypotension is the supine hypotensive syndrome. After 20 weeks the enlarging uterus has risen to the level of the IVC reusltin in compression when the mother is supine.
Caval obsturction limits preload
-Blood volume become increasingly larger for mulitgravidas and for twin, twiplet and quadruplet gestation. With this increased circulatory reserve clinical signs of maternal hypotension from acute traumatic bleeding may be delayed
Pulmonary
- Reduced o2 reserve due to reduction in FRC cause by diaphragm elevation and an increase in o2 consumption related to the growing foetus, uterus and placenta.
- minute ventilation and TV increase leading to hypocapnia. As such a Pco2 of 35-40 may indicate inadquate ventilation and impending respiratory decompensation
GIT
- LES sphincter tone and GI motility are decreased in pregnancy incrasing the possibility of aspiration in patietns with atlered LOC such as during intubation. Early GI decompression should be perofrmed in these circumstances
How should pregnant women wear seat bet
Improper placemetn of the lap belt causes a 3-4fold increasein force transmission throught he uterus.
For correct position the lap belt should be palced under the gravid abdomen, snugly over teh thighs with the nshoulder harness off to the side of the uterus between the breasts and over the midline of the clavicle
Discuss foetal injury
There is a high risk of foetal loss in the pregnant trauma patient.
Poor feotal outcome is predicted by
-maternal hypotension
-Acidosis (hypoxia, lowered ph)
-Feotal heart rate <110
40% mortality if mother sustains life threatening injury
DIC which may be caused by feotal products entering the maternal circulation is a major predictor of foetal demise.
Discuss placental injury
Leading cause of feotal death after blunt injury is placental injury.
Placental separtation occurs when the non eleastic placenta shears away from the elastic uterus during sudden defomration of the uterus.
Becuase deceleration injury can be as damaging to the placenta as direct trauma - abruption can occur with little to no eivdence of external trauma.
Diagnosis of abruption can be made on clinical grounds: US and Kleihaure Betke test are of limited use
Most sensitive indicator of placental abruption is feotal distress - other classic finding include
- vaginal bleeding
- abdominal cramp
- uterine contraction
- maternal hypovolaemia
Placental abruption can lead to the develop of DIC as feotal thromboplastin is released into the maternal circulation.
Discuss changes in lab values during pregnancy
Increased plasms volume and RBC cause physiological anaemia
Despite lower haematocrit there is an overall increase in o2 carrying capacity as the total red cell mass is increased.
Placental progesterone directly stimulates the medullary resp center producing a lower paco2 from the second trimester until term.
ECG: LAX, with flattened t-waves or q-waves in lead 3 and augmented voltage uniploar left limb lead
Discuss Foetal maternal haemorrhage and the Kleihauer-Betke test
Foetal maternal haemorrhage, the transplacental bleeding of foetal blood into the normally sperate maternal circulation is a unique complciation of pregnancy
Massive feotmaternal transplancetnal haemorrhage causes alloimmunization in Rh incompatibilty but also endagers the foetus by causing severe foetal aneami, foetal dsitress and possible exsanguination.
The Kleihauer test quantifies the amount of FMH. Most lab screen for FMH of 5ml or more even though the amount of FMH suffiecient to sensitize most Rh -ve women is well below this - as such mother should be treated prophylactically if any abdominal trauma
Discuss radiography in pregnant women
Adverse effects tot he foetus are inlikley if radiation exposure is less than 50mGy
CT head - 0mGY CT chest - 0.2 mGY CTPA - 0.2 mGY CT abdom 4 mGY CT abdo pelvis 25 mGY CTa aortqa 34 mGY
Discuss maternal resus - primary survey
Two resus teams
Early consultation with O&G, neonatologist or paeds (likley all three)
Foetal monitor, portable ultrasound and neoresus should be available
ADT should be given
RhIG should be available for -ve mothers - Massive FMH likley exceeds the efficacy of one 300mic dose and the Kleihauer Betke test can be used to guide effective dosing .
A: Should be done promptly with RSI if indicated to avoid higher risk of aspirationin pregnancy. High tidal volumes and a resp alkalosis should be aimed for witha pco2 of 30mmhg
B: o2 applied promptly as reduced o2 reserve and icnreased o2 consumption. Foetus is very vulnerable to reduction in o2
C: Due to physiological changes in pregnancy HR and BP are not consistenly reliable predictors of foetal and maternal HD
- Uterine blood flow is markedly reduced when maternal ciculation is compromised. As a result after an acute blood loss uterine blood flow can be substantially decrased while maternal blood pressure remians normal.
- vasopressors should be avoided as much as possible as they produce foetal distress by further decreasing uterine bloodflow.
- Beyond 20 weeks gestation tiltiing the patient to approximatly 30 degrees to the left helps alliviate aortocaval compression.
Primary survey is modified to assess uterine size and the presence of foetal heart tones if the patient is severly injuryed. Uterine size from the pubic symphysis to fundus is a good estimate of gestation. The feotus is potentially viable when the dome of the uterus extends beyond the umbilicus.
Discuss maternal resus secondary survey
Physical examination of the abdomen frequently unreliable in the nonpregnant patient is even more inaccurate with changin organ position seen in pregnancy
Pelvic exam begins with sterile speculum examination allowing direct visualization to detect possible truam in the gential tract, the degree of cervical dilation and the source of any observed vaginal fluid.
PV bleeding suggest placental abruption and a watery dsichareg suggest rupture of the membrane. If vaginal fluid placed on a slide dries and crystalises in a ferning patten is is amniotic fluid and not urine.
Bimanaul limited to assessing for bony injury.
Discuss foetal evaluation in maternal trauma
Focuses on the feotal heart rate and movement.
Once heart confirmed intermittent monitoring is likley sufficient. If viable continous external monitoring maintained throughout all diagnostic and therapeutic procedures may be useful in directing therapeutic procedure. - Such monitoring may also benifit mother as foetal HD are more senstive to decrease in maternal blood flow and oxygenation than are most measure of the mother.
Normal foetal heart rate ranges from 120-160 BPM. Heart variability has two components
-beat to beat variability measures autonomic nervous function
-long term variability indicates foetal activity
Loss of these warns of feotal CNS depression and reduced movement
Late deceleration are an indication of foetal hypoxia. These decels are small in amplitude and occur after the peak or conclusion of a uterine contraction.
Early decel are large occur with contraction and recover to baseline after - nthese may be vagally mediated
-variable decel are large can occur at any time and can be associated with umbilical cord compresison.
Discuss recommended monitoring in a stable mother and foetus post trauma
4 horus of CTG extended to 24 hours if at any time during the first 4 horus there are more than 3 contractions per hour (uterine irritability), uterine tenderness persists, results on a foetal monitor strip are worrisome, vaginal bleeding occurs, the membranes rupture or any serious maternal injuryis present.
On discharge mother should be asked to record foetal movements during the next week - fewer than 4 movement per hour patient should return for review,.
Discuss defib in pregnancy
Safe - monitor the foetal heart during maternal cardioversion
Discuss perimortem c-section
Restoration of maternal and thus feotal circulation is the optimal goal with maternal HD instability.
However extended and exclusive attention to the mother in CPR arrest may precent recovery of a viable feotus.
If no response to ALS should be made within 4 minutes. - should only be considered if uterus size is greater than umbilicus 24-26 weeks gestation.
-Delivery increase venous return and Co by 25-30% and may lead to survival beneift fro mother.
CPR continuiing a midline vertical incision from the epigastrium to the symphysis pubis is made. The uterus is then entered with a midline vertical incision - if necessary the placenta is incised to reach the feotus - once delived cord should be clamped and cut
