ITE CA-2 OB anesthesia Flashcards
4 classes of tocolytic drugs
β-adrenergic agonists,
calcium channel blockers,
cyclooxygenase inhibitors (e.g., NSAIDs), and
magnesium sulfate
B-agonists used to treat preterm labor
ritodrine and terbutaline
maternal effects of b-agonists to treat pre-term labor
cardiopulm: pulmonary edema, MI, tachycardia, vasocilation, hypotension, dysrhythmias
Endocrine: hyperglycemia, hyperinsulinemia, hypokalemia (from increased insulin), altered thyroid fxn, antidiuresis
Misc: tremor, palpitations, hallucinations, ileus (N/V), fever, nervousness
Fetal effects of b-agonists to treat pre-term labor
tachycardia, MI, myocardial hypertrophy, hyperglycemia, hyperinsulinemia
Neonatal effects of b-agonists to treat pre-term labor
tachycardia, hypotension, intraventricular hemorrhage, hyperbilirubinemia, hypocalcemia, hyperglycemia -> hypoglycemia
Pregnant women with cord injury above ___ may have an increased risk of preterm labor
Pregnant women with cord injury above T11 may have an increased risk of preterm labor
Pregnant women with cord injury above T11 may have an increased risk of ________
Pregnant women with cord injury above T11 may have an increased risk of preterm labor
For chronic lesions above ___, autonomic hyperreflexia occurs in > 85% of pregnancies
For chronic lesions above T6, autonomic hyperreflexia occurs in > 85% of pregnancies
How treat labor pain in patient with chronic lesion above T6
For chronic lesions above T6, autonomic hyperreflexia occurs in > 85% of pregnancies. Neuraxial anesthesia is often effective and placement of an intrathecal catheter may allow for continuous titration of the block. Most obstetric anesthesiologists choose epidural anesthesia in this situation. Lateral position is preferred for the procedure as the sitting position results in pooling of blood in the lower extremities.
Medical complications of spinal cord injury aggravated by pregnancy
Medical complications of spinal cord injury aggravated by pregnancy include decreased respiratory reserve, atelectasis, impaired cough, anemia, deep vein thrombosis, thromboembolic phenomena, chronic urinary tract infections, urinary tract calculi, proteinuria, renal insufficiency, decubitus ulcers, hypertension, and autonomic hyperreflexia.
Aspiration of meconium stained amniotic fluid treatment
Aspiration of meconium stained amniotic fluid can lead to meconium aspiration syndrome in newborns. Suctioning the oropharynx or intubating and suctioning the trachea of apparently vigorous infants has NOT been shown to be beneficial. If the infant born through meconium-stained amniotic fluid has poor muscle tone and inadequate breathing efforts, resuscitate under a radiant warmer. Positive pressure ventilation should be initiated if the infant is not breathing or the heart rate is less than 100/min after the initial steps are completed.
Can diagnose preeclampsia in absence of proteinuria with any of what
thrombocytopenia, renal insufficiency, pulmonary edema, cerebral disturbances, or hepatic dysfunction.
Chronic hypertension in pregnancy
Chronic hypertension involves pre-pregnancy blood pressures greater than 140/90 mmHg or elevated blood pressure that fails to resolve after the post-partum period.
Gestational hypertension
Gestational hypertension manifests as elevated blood pressure after 20 weeks gestation, without any systemic manifestations, and resolves 12 weeks postpartum.
Preeclampsia is
Preeclampsia is new onset hypertension and proteinuria after 20 weeks gestation. If hypertension exists without proteinuria, preeclampsia is also defined as thrombocytopenia, impaired liver function, new development of renal insufficiency, pulmonary edema, or new-onset cerebral or visual disturbances.
The most common cause of early postpartum hemorrhage and risk factors
The most common cause of early postpartum hemorrhage is uterine atony which results in continued bleeding from intrauterine vessels that are torn with placenta delivery. Risk factors for uterine atony include multiparity, multiple gestations, polyhydramnios, chorioamnionitis, prolonged labor, oxytocin-induced labor, and mechanical factors.
Primary pulmonary hypertension in pregnancy
Primary pulmonary hypertension (PPH) in pregnant patients has a high mortality rate usually from right heart failure. The anesthetic technique is aimed at minimizing increases in peripheral vascular resistance. PPH is most commonly seen in younger women and is poorly tolerated in pregnancy; pregnancy is discouraged in these patients and termination is advised should pregnancy occur.
The normal physiological changes of pregnancy are poorly tolerated by women with pulmonary hypertension. Pregnancy is associated with increased plasma volume and decreased systemic vascular resistance, both resulting in an increase in cardiac output. In healthy women, a decrease in pulmonary vascular resistance accommodates the requirements for increased cardiac output. In women with pulmonary hypertension, pulmonary vascular disease prevents the fall in pulmonary vascular resistance, leading to a rise in pulmonary artery pressure with increased cardiac output. Ultimately, the necessary increase in cardiac output cannot be achieved resulting in right heart failure.
Anesthetic considerations for pregnant patient with primary pulmonary hypertension.
The biggest difficulty in planning for an anesthetic in the pregnant patient with PPH is minimizing increases in PVR (pulmonary vascular resistance). Pain during labor and vaginal delivery is especially detrimental because it may further increase pulmonary vascular resistance and decrease venous return. Neuraxial analgesia is useful for preventing pain-induced increases in pulmonary vascular resistance. Dilute local anesthetic solutions with the addition of opioids will minimize the decrease in systemic vascular resistance (SVR). General and epidural anesthesia have been used for cesarean delivery. Spinal anesthesia may result in a sudden decrease in SVR and is thus not recommended for cesarean delivery. Risks of general anesthesia include increased pulmonary artery pressures during laryngoscopy and tracheal intubation, the adverse effects of PPV on venous return, and the negative inotropic effects of volatile anesthetics. In addition to oxygen, the administration of isoproterenol, inhaled nitric oxide, calcium channel blockers, or sildenafil may be useful for decreasing pulmonary vascular resistance. Hemodynamic monitoring, including systemic and pulmonary arterial pressures, remains controversial in these patients with no evidence to support the use of pulmonary artery catheters. Pulmonary artery rupture and thrombosis are risks of pulmonary artery catheters in the presence of pulmonary hypertension, but some argue that the benefits in these critically ill patients appear to offset these potential hazards.
First line for uterine atony
IV oxytocin
Treatment for uterine atony that is contraindicated in the setting of pregnancy-induced hypertension or preeclampsia and why
Methylergonovine maleate is contraindicated in the setting of pregnancy-induced hypertension or preeclampsia since it is an ergot derivative that may lead to hypertensive emergency.
Treatment for uterine atony contraindicated in asthma
Carboprost tromethamine is contraindicated in patients with significant reactive airway disease since it has prostaglandin-like effects and can cause bronchospasm.
Most effective way to reduce risk of aspiration in OB patients
avoid a general
Why OB patient greater risk of aspiration?
If general anesthesia cannot be avoided, know that the patient will be at increased risk of aspiration compared to a non-pregnant patient, primarily because the increased incidence of difficult airway and the decreased competency of the lower esophageal sphincter.
Main factor for development of pneumonitis in aspiration?
Prophylaxis?
If aspiration occurs, the main factor for the development of pneumonitis appears to be the pH of the aspirate. For prophylaxis, the ASA guidelines recommend avoiding solid food in laboring patients and considering non-particulate antacids, H2-receptor antagonists, and/or metoclopramide before cesarean section.
labor stage 1
Stage I: A) Latent phase
Variable duration
Starts at onset of labor
Complete when the rate of cervical dilation increases (~ 3 cm)
B) Active phase (contractions every 2-3 mins, last 1 min, up to 70 mm Hg)
acceleration phase
phase of maximal slope
deceleration phase
Normal active labor should progress 1 cm/hr
Most common measure of uterine activity is the Montevideo unit (avg intensity frequency per 10 minutes)
labor stage II
Stage II: interval between maximal dilation and delivery (20-120 mins)
labor stage III
Stage III: starts after delivery of the baby and ends with placental delivery (5-20 mins)
seizure threshold in pregnancy
Higher estrogen levels during pregnancy lower the seizure threshold. Pregnancy can cause variable effects on the frequency of seizures. A variety of etiologies may increase seizure frequency in pregnant women. Greater sodium retention and water retention are suggested methods of increased seizure activity. Also, anticonvulsant drug levels can be decreased during pregnancy secondary to decreased plasma protein binding and greater drug clearance.
Estrogen is a proconvulsant, whereas, progesterone is an anticonvulsant.
labor stage one spinal segments
The first stage of labor is defined as the beginning of labor to maximal cervical dilation. Pain impulses arise primarily from the uterus during this stage of labor. These stimuli enter the spinal cord at the T10, T11, T12, and L1 spinal segments
labor stage II spinal segments
The second stage of labor is defined as the interval between full cervical dilation and delivery of the infant. Pain impulses primarily arise from stretching of the perineum. These stimuli arise from nerve fibers through the pudendal nerve to the spinal cord at S2, S3, and S4 levels.
lumbar sympathetic block would cover what stages of labor
stage I
caudal epidural would cover what stages of labor
stage I and II (not sure about III but it probably would)
paracervical block
A paracervical block is an alternative block technique in pregnant women. It adequately can provide analgesia for the first stage of labor. The block is performed by injecting local anesthetic in the fornix of the vagina around the cervix to block nerve transmission through the paracervical ganglion. This block provides no pain relief for the second stage of labor.
pudendal nerve block
A pudendal nerve block covers the lower sacral nerve roots (S2-S4) and provides sensory innervation to the lower part of the vagina, vulva, and perineum. The block is completed by depositing local anesthetic behind each sacrospinous ligament. This nerve block is not useful for labor analgesia, however, it provides satisfactory analgesia for outlet forceps delivery.
med to give in case of shoulder dystocia
Shoulder dystocia is a fetal life-threatening emergency. Nitroglycerin provides fast-onset uterine relaxation to assist with obstetric manipulation and delivery.
Nitroglycerin is a faster and more potent uterine relaxant as compared to beta-agonist terbutaline although its duration of action is much shorter.
How do clotting factors change in pregnancy
Pregnancy is a prothrombotic state with increased levels of many clotting factors. Factors VII, VIII, IX, X, and XII levels are all increased. In addition there is a decrease in factor C & S levels. This causes shorter PT and PTT times. However, not all factors are increased during pregnancy with factors XI and XIII levels decreasing slightly.
Platelets stable or slight decrease
The risk of deep venous thrombosis (DVT) is increased during pregnancy mainly because of an increase in circulating levels of fibrinogen.
The risk of deep venous thrombosis (DVT) is increased during pregnancy mainly because of an increase in circulating levels of fibrinogen.
Fibrinogen is factor __
1
Risk factors for fetal drug toxicity
Drug characteristics that facilitate placental transfer include: small size (< 500 Dalton’s), nonionized/lipid soluble, poorly protein bound, and high maternal concentration. Drugs that undergo ion trapping (most importantly local anesthetics) can accumulate more quickly in the setting of fetal acidosis.
Some important drugs that do not cross the placenta:
Some important drugs that do not cross the placenta:
He Is Going Nowhere Soon = Heparin, Insulin, Glycopyrrolate, Non-depolarizing muscle relaxants, Succinylcholine.
How reverse in OB without sugammadex
The inability of glycopyrrolate to cross the placenta is important to consider when reversing a pregnant woman from neuromuscular blockade. Neostigmine is also a quaternary structure but does cross the placenta to a small degree. If glycopyrrolate is administrated with neostigmine, the fetus will accordingly be exposed to more neostigmine than glycopyrrolate and can become bradycardic. For this reason, atropine may be preferred in combination with neostigmine to antagonize non-depolarizing neuromuscular blockade in pregnant patients.
Platelets in pregnant woman
Platelets may lead to Rh sensitization and consideration should be given to administering Rh immunoglobulin (often referred to by its commercial name RhoGAM) to women of child-bearing age or younger.
Double Bohr effect
The double Bohr effect describes a condition in the placenta where the maternal Bohr effect and the fetal Bohr effect occur in opposite binding conditions. From the maternal side the hemoglobin is in an acidic environment, which promotes oxygen offloading. The fetal hemoglobin on the placental side is in an alkalotic state, which promotes oxygen uptake or binding. The double Bohr effect accounts for somewhere between 2-8% of oxygen transfer across the placenta.
Fetal hemoglobin level
The normal fetal hemoglobin concentration is approximately 17mg/dL. The normal maternal hemoglobin concentration is 12mg/dL
How much does maternal blood vol increase in pregnancy?
By what mechanism?
An increase of up to 45% of maternal blood volume is seen during pregnancy. This effect occurs early within pregnancy and is due to sodium retention via the renin-angiotensin system.
Oxy-hgb dissoc curve shift in pregnancy
Right
Maternal CO trend in pregnancy and what is the peak. When is HR vs stroke volume
Maternal cardiac output progressively increases during pregnancy and throughout labor, reaching its peak immediately following delivery (2.5x prepregnancy values). Cardiac output then quickly declines postpartum and begins to approach prepregnant values by two weeks postpartum.
Maternal cardiac output increases significantly throughout pregnancy, please see figure below. In the first trimester, maternal heart rate increases and accounts for the 35-40% rise in cardiac output seen by the end of the first trimester. During the second and third trimester, stroke volume increases. At the end of the second trimester, cardiac output is 50% greater than the prepregnant state and will remain at this level during the third trimester, just prior to the onset of labor. The onset of labor induces further progressive increases in cardiac output which amounts to an increase of as much as 110% above the prepregnant state.
Neonatal resuscitation
During neonatal resuscitation, positive pressure ventilation is indicated if the neonate’s heart rate drops below 100 bpm. If the heart rate falls below 60 bpm for more than 30 seconds despite adequate ventilation, chest compressions should be started. If the heart rate remains below 60 bpm despite adequate ventilation and chest compressions, epinephrine should be administered.
Block for stage 1 of labor and risk
Pudendal block provides analgesia for the 2nd stage of labor. By blocking the pudendal nerve vaginal and perineal distention pain is blocked.
A paracervical block provides analgesia for the 1st stage of labor especially cervical dilation. However, paracervical blocks are associated with a high rate of fetal bradycardia. The rate of fetal bradycardia is increased if fetal acidosis is present.
Block for stage 2 of labor
Pudendal block provides analgesia for the 2nd stage of labor. By blocking the pudendal nerve vaginal and perineal distention pain is blocked.
A paracervical block provides analgesia for the 1st stage of labor especially cervical dilation. However, paracervical blocks are associated with a high rate of fetal bradycardia. The rate of fetal bradycardia is increased if fetal acidosis is present.
Labor stage one dermatome levels
T10-L1
Stage 2 of labor dermatomes
T12-L1, S2 - S4
Preeclampsia
- endocrine
- SVR
- uterine blood flow
- placental blood flow
In preeclampsia, there is an elevation in thromboxane A2 levels and a decrease in prostacyclin levels leading to a primarily vasoconstricted state. Preeclampsia is characterized by global vascular hyperreactivity leading to intravascular volume depletion, high systemic vascular resistance, uterine vasoconstriction of the myometrium, and decreased uterine and placental blood flow.
Preeclampsia
- more or less nitric oxide
- platelets?
- renal blood flow
- why pulm edema
Endothelial cell activation leads to reduced nitric oxide production and platelet activation. Renal blood flow is decreased leading to decreased urine output. Pulmonary edema occurs secondary to capillary leakage and increased inflammatory response. The hypercoagulable state and platelet activation is juxtaposed with a coagulopathy secondary to decreased platelet counts and prolonged PTT.
Drug characteristics affecting maternal to fetal placental transfer Characteristics Increased transfer Decreased transfer Size (molecular weight) Charge Lipid solubility Ionization Protein binding Free drug fraction
Drug characteristics affecting maternal to fetal placental transfer
Characteristics Increased transfer Decreased transfer
Size (molecular weight) < 500 Daltons
Charge Uncharged Charged
Lipid solubility Lipophilic Hydrophilic
Ionization Unionized Ionized
Protein binding Low (albumin) High (α-1-acid glycoprotein)
Free drug fraction High Low
serum albumin concentration high or low in pregnancy
decreases because of plasma expansion
serum alpha and beta globulins in pregnancy
increase
transferrin level in pregnancy
increase
TIBC in pregnancy
increases
serum iron in pregnancy
decreases
Amniotic fluid embolism is characterized by
When emergent c section?
Amniotic fluid embolism is characterized by an early stage with pulmonary vasospasm and right heart dysfunction or failure leading to a second stage with pulmonary edema and left heart dysfunction or failure. Maternal coagulopathy (consumptive) occurs in the majority of cases. Emergency cesarean section is required if uterine hypertonus leads to fetal bradycardia and distress.
Significant risk factors for preterm labor include a history of previous preterm delivery, non-Hispanic black race, and multiple gestations.
Significant risk factors for preterm labor include a history of previous preterm delivery, non-Hispanic black race, and multiple gestations.
Other factors associated with preterm labor include extremes of age, low socioeconomic status, low prepregnancy body mass index, abnormal uterine anatomy, abnormal cervical anatomy, trauma, abdominal surgery during pregnancy, tobacco use, and substance abuse.
An interpregnancy interval of less than six months is a factor associated with preterm labor.
how do following affect risk of PDPH after accidental dural puncture with epidural needle: gender obesity needle gauge age pregnancy previous history
females more likely to get PDPH obesity decrease smaller gauge (higher number) decrease older age decrease (under 40 years most common; over 60 rare) pregnancy decrease previous history increase
options other than nitroglycerin for uterine relaxation
Other options include inhaled amyl nitrite and beta-adrenergic agonists (IV ritodrine, IV salbutamol, IV terbutaline).
Cervix covered by which dermatomes
T10-L1
Vagina and perineal covered by which dermatomes
S2-S4
Risk factors for uterine rupture in the parturient
Risk factors for uterine rupture in the parturient include ***prior uterine surgery*** (upper segment scar >> lower segment scar), uterine hypercontractility, oxytocin use, prostaglandin use, prolonged labor, dystocia, multiparity, multiple gestations, congenital uterine anomalies, polyhydramnios, and trauma.
Preeclampsia diagnostic criteria
Preeclampsia is diagnosed with the presence of hypertension (> 140/90 mm Hg) after 20 weeks with proteinuria or the presence of one of the 6 features listed below (these are used in the diagnosis of preeclampsia with severe features):
1) BP ≥ 160/110 on two occasions at least four hours apart
2) Thrombocytopenia < 100,000
3) Impaired liver function
4) Progressive renal insufficiency
5) Pulmonary edema
6) New-onset cerebral or visual disturbances
How much protein for proteinuria in preeclampsia
Proteinuria:
• Greater than or equal to 300 mg per 24-hour urine collection (or this amount extrapolated from a timed collection)
OR
• Protein/creatinine ratio greater than or equal to 0.3 mg/dL
• Dipstick reading of 1+ (used only if other quantitative methods not available)
Severe Features of Preeclampsia
Severe Features of Preeclampsia
1) Systolic blood pressure of 160 mm Hg or higher, or diastolic blood pressure of 110 mm Hg or higher on two occasions at least 4 hours apart while the patient is on bed rest (unless antihypertensive therapy is initiated before this time)
2) Thrombocytopenia (platelet count less than 100,000/microliter)
3) Impaired liver function as indicated by abnormally elevated blood concentrations of liver enzymes (to twice normal concentration), severe persistent right upper quadrant or epigastric pain unresponsive to medication and not accounted for by alternative diagnoses, or both
4) Progressive renal insufficiency (serum creatinine concentration greater than 1.1 mg/dL or a doubling of the serum creatinine concentration in the absence of other renal disease)
5) Pulmonary edema
6) New-onset cerebral or visual disturbances
Effects at what ranges for magnesium
Therapeutic range: 5-9
>5-10 depressed cardiac conduction, widened QRS, and prolonged PR intervals on ECG
>7 Hypotension, bradycardia, vasodilation
Deep tendon reflexes are reduced at magnesium levels >5 mg/dL and are lost at >12 mg/dL.
Muscle weakness (can cause blurred vision), and hypoventilation (reflecting diaphragm weakness) occur at magnesium levels of 7-12 mg/dL.
15-20 Resp arrest
>25 asystole
How is magnesium cleared
Patients with renal failure are more prone to hypermagnesemia, as excretion of magnesium is directly correlated to glomerular filtration rate.
Terbutaline
Terbutaline is a tocolytic used to produce uterine muscle relaxation, thus facilitating intrauterine version procedures.
Carboprost
Carboprost tromethamine (15-methyl prostaglandin F2α) is a uterotonic used to increase uterine muscle tone following delivery.
What is hemabate called
Carboprost
Carboprost contraindications
pulm hypertension
reactive airway disease (bronchospasm, increased intrapulm shunt, hypoxemia)
Carboprost mechanism
increase in myometrial free calcium concentration
Terbutaline side effects
A side effect of terbutaline is tachycardia and pulmonary edema (beta1-agonist effects)
Resp changes in the parturient
Expiratory reserve volume, functional residual capacity, and total lung capacity all see a decrease as the fetus nears the term. The vital capacity, which includes inspiratory reserve volume, tidal volume, and expiratory reserve volume, remains unchanged as there is a concomitant increase in the inspiratory reserve volume and tidal volume that occur to accommodate an increased minute ventilation for the increase in oxygen demands.
Respiratory changes in the parturient include a cephalad movement of the diaphragm with a concomitant increase in the anteroposterior and transverse diameter of the thoracic rib cage. There is a decrease in the functional residual capacity and its components as well as an increase in the inspiratory reserve volume. Airway resistance remains relatively unchanged.
Uterine rupture vs dehiscence
Dehiscence is a wall defect that does not result in hemorrhage or fetal distress. This condition, therefore, does not warrant emergency surgical intervention. Uterine rupture can be a catastrophic event in which the integrity of the entire thickness of the myometrial wall is compromised. This condition can result in hemorrhage and fetal distress, therefore mandating emergency surgical intervention. Rupture of a uterine scar carries increased morbidity and mortality to both mother and fetus. This is largely because of the vascularity of and placental implantation within the anterior uterine wall.
Alveolar dead space increase or decrease in active labor and why
Reduced secondary to increase in cardiac output
renal insufficiency labs in pregnant women
A serum creatinine concentration greater than 0.8 mg/dL and a blood urea nitrogen concentration greater than 13 mg/dL (which are normal values for the nonpregnant patient) suggest renal insufficiency in the pregnant woman.
Normal fibrinogen levels
Normal fibrinogen levels are about 225-500 mg/dL
Risk factors for failed neuraxial anesthesia during cesarean delivery include
Risk factors for failed neuraxial anesthesia during cesarean delivery include increasing maternal size, late labor epidural placement, and a rapid decision-to-incision interval.
Initial treatment for hypermagnesemia
Initial treatment for hypermagnesemia in the face of hemodynamic compromise or extreme muscle weakness is calcium chloride or gluconate. Dialysis is the definitive treatment but may take a long time to institute.
APGAR score
skin color - blue; blue extrem, pink chest; pink
heart rate - absent; <100; >100
reflex irritability - no response; feeble cry w stim; strong response w stim
muscle tone - none; some flexion; active
respiratory effort - absent; weak or irregular; strong and regular
amniotic fluid embolism
2 phases
result of
AFE is divided into two phases: cardiovascular collapse followed by consumptive coagulopathy
immune response to amniotic fluid in maternal pulm vasculature
Polyhydramnios
associated with
Polyhydramnios is increased amniotic fluid volume. It occurs in 1% of pregnancies and is associated with increased fetal urine production or fetal structural abnormalities preventing fetal swallowing. Polyhydramnios is associated with preterm labor and premature rupture of membranes as well as postpartum uterine atony.
Other causes include neuromuscular disease inhibiting fetal swallowing, maternal diabetes, congenital infections, fetal anencephaly, fetal trisomies, and twin gestation with twin-to-twin transfusion syndrome.
maternal ACE-i use ass’d with ____hydramnios
oligo
The treatment of choice for polyhydramnios is
The treatment of choice for polyhydramnios is indomethacin
Factors that increase spread of epidural
Increased volume of the injectate, positive airway pressure, lateral/Trendelenburg position, and increased age all generally increase the epidural spread of local anesthetics. Of these, the volume of injection has the most significant impact.
Speed of injection effect on epidural
Speed of injection appears to impact the onset rather than the spread of local anesthetic.
Changes in pregnancy
Cardiac Output
Heart Rate
Stroke Volume
Intravascular Volume
Central Venous Pressure
Plasma Volume
Red Blood Cell Mass
Systemic Vascular ResistanceCardiac Output Increased 40-50%
Heart Rate Increased 15-25%
Stroke Volume Increased 30%
Intravascular Volume Increased 35%
Central Venous Pressure No Change
Plasma Volume Increase 45%
Red Blood Cell Mass Increased 20%
Systemic Vascular Resistance Decreased 15-20%
The major disadvantage of a paracervical nerve block during labor is
The major disadvantage of a paracervical nerve block during labor is a high frequency of fetal bradycardia associated with decreased fetal oxygenation and fetal acidosis.
Run a code on OB
American Heart Association guidelines recommend beginning perimortem cesarean (resuscitative hysterotomy) at four minutes and completing delivery of the fetus by five minutes following cardiac arrest. Manual left uterine displacement should be performed during resuscitation, including during the performance of perimortem cesarean until the fetus is delivered.
Risk factors for placenta accreta
Advanced maternal age multiparity prior uterine surgery placenta previa smoking multiparity previous myometrial tissue (previous myomectomy or Asherman syndrome)
However, the number one risk factor is previous cesarean section with the placenta overlying the surgical scar.
placenta accreta management
Management is planned preterm cesarean section with the placenta left in situ.
Fetal heart rate variability is primarily determined by the
Fetal heart rate variability is primarily determined by the parasympathetic tone of a fetus and is decreased during periods of CNS depression.
Variable decelerations characterized by:
Characteristics of variable deceleration:
1) Visually apparent abrupt decrease in FHR occurs
2) Abrupt FHR decrease is defined as from the onset of the deceleration to the beginning of the FHR nadir of less than 30 seconds
3) The decrease in FHR of 15 bpm or greater occurs, lasting 15 seconds or longer and less than 2 minutes in duration
4) When the variable decelerations are associated with uterine contractions, their onset, depth, and duration commonly vary with successive uterine contractions
Significance of decelerations:
early
late
variable
Early decelerations are unrelated to fetal oxygenation while late and variable decelerations are related to interrupted fetal oxygenation.
Things that cause uterine distention make breech presentation more or less likely
more
most common causes for delay in latent phase of labor
An unripe cervix and false labor are two of the most common causes for a delay in the latent phase of labor.
Regional anesthesia and delay of labor
The controversy of whether regional anesthesia delays the latent phase of cervical dilation continues. Most controlled studies have not shown a significant prolongation of labor in the latent phase or active phase with regional anesthesia
High-dose oxytocin metabilic derrangement
High-dose oxytocin has antidiuretic and natriuretic effects which can cause hyponatremia. (similar structure to vasopressin)
oxytocin structurally similar to
Due to structural similarities between oxytocin and vasopressin, high-dose vasopressin administration can cause uterine contractions.
Fetal acidosis and local anesthetics
Local anesthetics are basic drugs that cross placental membranes via simple diffusion. Fetal acidosis promotes conversion of the nonionized form of local anesthetic into the ionized form. As ionized drugs do not easily cross the placental membrane, this leads to accumulation of local anesthetic within the fetus, a phenomenon called “ion trapping.”
ABG in pregnancy
Increased minute ventilation in pregnancy causes a respiratory alkalosis as PaCO2 falls to approximately 30 mmHg. An incomplete compensatory metabolic acidosis (bicarbonate falls to 20-21 mEq/L) means pH will rise slightly (around 7.44). Increased alveolar ventilation also leads to an increase in PaO2 (to 105-107 mmHg) early in pregnancy although this will slowly decline back towards normal as pregnancy progresses.
Volatiles effect on uterus in pregnancy
N2O
All volatile halogenated agents cause a dose-related relaxation of uterine smooth muscle. Nitrous oxide has no effect on uterine muscle tone.
The concentration of sevoflurane and desflurane required to decrease myometrial contractility by 50% varies from 0.8 MAC to 1.7 MAC. In comparison, the same decrease is seen with isoflurane with MAC values of approximately 2.4.
d-dimer in pregnancy
increased
INR peak after donor hepatectomy
INR increases following donor hepatectomy, peaking on POD 1-3, which should be considered prior to epidural administration.
Cause of shivering during labor
Shivering during labor occurs irrespective of whether neuraxial anesthesia is employed. It is more likely to occur in patients who have had neuraxial anesthesia and it may be secondary to changes in body temperature, although the pathophysiology is not completely understood and non-thermoregulatory factors may contribute.
The supine position for pregnant patients near term may result in
The supine position for pregnant patients near term may result in aortocaval compression. Supine hypotensive syndrome results from partial or complete occlusion of the inferior vena cava, causing decreased venous return to the right ventricle. Partial compression of the aorta may also occur, causing increased blood pressure in the maternal upper extremities and hypotension in the lower extremities.
Oligohydramnios
what % of pregnancies
what abnormalities
what med can cause it
Oligohydramnios occurs in 4% of pregnancies and is associated with fetal lung hypoplasia and musculoskeletal abnormalities. ACE inhibitor use has been linked to developing oligohydramnios and should be avoided in pregnancy.
Maternal administration of magnesium
Maternal administration of magnesium can have profound effects on the neonate, such as hypotonia, depressed respiratory drive, and poor feeding (secondary to poor sucking capabilities related to generalized weakness). Care is largely supportive.
The following methods can be used for pain relief in the first stage:
The following methods can be used for pain relief in the first stage: epidural, spinal, paracervical block, CSE, and remifentanil infusion if regional or nerve block is contraindicated. However, it should be noted that spinal local anesthetics may wear off before delivery thus opioid spinal injections may be beneficial.
The following methods can be used for pain relief in the second stage of labor:
The following methods can be used for pain relief in the second stage of labor: spinal, epidural, CSE, and pudendal block.
Drugs that don’t cross the placenta
tHINGS Heparin Insulin NDNMB Glycopyrolate Sux ...also phenylephrine
what dermatomes need to be blocked for
c section
stage 1 labor
stage 2 labor
Adequate neuraxial anesthesia for a cesarean section is best achieved through sensory blockade of the T4-S4 dermatomes.
For adequate analgesia for stage I labor, the T10-L1 dermatomes should be covered.
The second stage of labor requires additional coverage at S2-4.
The risk factors for bradycardia with spinal
The risk for, and severity of, bradycardia increases with higher block height and occurs via several different mechanisms. First, blockade of the sympathetic cardiac accelerator fibers at T1-T4 can decrease baseline heart rate. Second, decreases in preload triggers several downstream effects including vagally-mediated reflexes which slow the heart rate in response to central volume depletion, or the Bezold-Jarisch reflex, which causes bradycardia in response to decreased cardiac filling pressures.
Additional risk factors for bradycardia include age < 50, ASA 1 physical status, baseline heart rate < 60, and concurrent β-blocker use. Again, it should be noted that the risk factors for cardiac arrest include ASA physical status 1 patients who are young.
Meralgia paresthetica in pregnancy
Meralgia paresthetica (MP) is entrapment of the LFCN, associated with burning pain over the distribution. Pregnant women often present with MP following prolonged labor. The LCFN may be impinged against the inguinal ligament while their legs are in stirrups.
fibrinogen in pregnancy
Pregnancy is a state of hypercoagulability with a most notable increase in the levels of fibrinogen, up to double the concentration, in order to limit postpartum hemorrhage.
what coag factors increase in pregnancy
Factors that increase include I (fibrinogen), VII, VIII, IX, X, XII, and von Willebrand factor which peak at the time of parturition.
what coag factors decrease in pregnancy
Factors that decrease include XI, XIII, antithrombin III, and tPa
Also, resistance to activated protein C occurs as well as a decline in the level of protein S.
what happens to PLTS, red cell mass, plasma volume in pregnancy
A dilutional and consumptive thrombocytopenia occurs which usually results in a decrease of 10% in platelet count. About 6-15% of pregnant patients have a platelet count of less than 150 * 10^9/L. Other hematologic changes that occur include an increase in red blood cell mass of 20-30% and an increase in plasma volume of 40-50% resulting in dilutional anemia
contraindications to the 2 common second line uterotonics
Several second-line therapies exist to help control postpartum hemorrhage due to uterine atony. Being aware of these contraindications - methylergonovine in coronary artery disease and preeclampsia/eclampsia ( it can cause coronary artery spasm and systemic vasoconstriction that increases systemic hypertension.), and carboprost in asthma ( because it increases pulmonary vascular resistance that can cause pulmonary hypertension and induces bronchoconstriction) - is essential to providing appropriate anesthetic care.
define fetal tachycardia
160+
magnesium levels at which loss of deep tendon reflexes
10-12
name 3 things ass’d with PDPH
tinnitus, diplopia, CN VII palsy
what stage of labor corresponds to greatest increase in cardiac output
stage 3
fibrinogen in pregnancy
this card said decreased but i think that is wrong
5 minute apgar score ass’d with
neurologic outcome
3 risk factors for uterine atony
long labor, macrosomia, polyhydramnios
Which of the following maternal treatments will MOST LIKELY benefit a fetus when given for preterm labor without rupture of membranes?
Corticosteroid therapy has been shown to improve neonatal outcome and magnesium therapy has been shown to provide some fetal neuroprotection when used in the setting of preterm labor. Tocolytic therapy is not advocated for routine use except to prolong pregnancy long enough to allow for corticosteroid administration.
Treatment of hypermagnesemia includes
Treatment of hypermagnesemia includes 1) stopping the source of magnesium, 2) antagonizing the effects of magnesium with calcium, and if moderate or severe 3) increasing elimination of magnesium with loop diuretics or possibly hemodialysis.
Fetal acidemia
Fetal acidosis may be assessed through fetal scalp blood gas analysis. Lactate or pH levels that fall in the range for fetal acidemia may prompt obstetricians to consider transitioning to emergent operative delivery, especially in the setting of non-reassuring fetal heart monitoring.
Fetal acidemia is defined as pH < 7.21 or lactate > 4.8 mmol/L.
