ANESTHESIA FOR ESOPHAGEAL SURGERIES

Approaches: Ivor Lewis (laparotomy and right thoracotomy, transhiatal (abdominal and neck incisions), left thoraco abdominal approach

Concerns:

Preoperative Chemotherapy
1. Less distinct tissue planes and increased bleeding
2. Bleomycin : pulmonary toxicity ; worsened by high oxygen concentrations
3. Doxorubicin: acute dysrhythmia, chronic cardiomyopathy

Incomplete Obstruction
1. Recurrent aspiration pneumonitis- decreased pulmonary reserve
2. Retained food products @ induction - increased risk of aspiration

History of smoking, alcoholism
1. Associated COPD
2. Alcoholic cardiomyopathy
3. If on antiplatelets for CAD, use of epidural may be contraindicated

Evaluation

1. CBC: check for infections
2. PFT-ABG-FLOW VOLUME LOOPS
3. CT/MRI- bronchoscopy; if required, to evaluate for presence of tracheal or bronchial compression
4. ECG, ECHO

Special points on Anesthetic technique

1. In thoracic or thoraco abdominal approach, placement of a DLT is indicated to provide OLV. If difficult airway, single lumen can be inserted first and then changed using a tube exchange catheter.
2. Surgeries involving only cervical or endoscopic approach don't require epidural
3. If epidural is planned placement and testing before induction is recommended
4. Significant third space loss : close monitoring of BP and Urine output
5. Transient compression of myocardium can produce dysrhythmia and hypotension : IBP will be helpful
6. PEEP- low tidal volume - low ventilator pressures can be lung protective strategies in OLV
7. Avoid excess fluids: anastamotic edema, pulmonary edema
8. Patients with significant intraoperative fluid shifts may develop airway edema- avoid premature extubation
8. If patient requires prolonged postoperative ventilation, DLT can be exchanged with single lumen tube, before shifting to icu.
9. Arrange platelets, ffp, cryoprecipitate etc.
10. CVP cannulation site should be determined by surgical approach
11. Prevent hypothermia
12. Take necessary precautions to avoid position related injuries; check radial pulse after placement of axillary roll. Can place pulseoximeter probe on down arm to check perfusion
13. Ensure normal potassium ( dysrhythmias)
14. Hypoxia during OLV : PEEP to ventilated lung, CPAP to non ventilated lung, return to double lung ventilation
15. Adequate BP is necessary for maintaining integrity of the anastamosis

16. POSTOPERATIVE

a. Recovery in head up position, ig risk of aspiration high
b. High index of suspicion for pneumothorax
c. Hoarseness = RLN injury
d.  SVT: adenosine. 6 mg iv push and repeat if needed to 12 mg ; AF - DC cardioversion, beta blockers, Amiodarone,  CCBs, pacing
e. DVT prophylaxis

Magnesium Sulphate therapy in preeclampsia

Continuous Intravenous Infusion

Magnesium sulfate 4-g to 6-g loading dose diluted in 100 mL fluid  administered intravenously over 15 minutes, followed by continuous intravenous infusion at 1 to 2 g per hour. Discontinue 24 hours after delivery or last seizure.

If convulsions persist after 15 min, give up to 2  gram more intravenously as a 20% solution at a rate not to exceed 1g/min. If the woman is large (> 70 kg) then an additional 2 grams may be given slowly

Only give the next IM dose, or only continue the IV infusion if:

Respiratory rate > 16/min
Urine output > 25 ml/h
Patellar reflexes are present

If urine output < 100 ml in 4 h and there are no other signs of magnesium toxicity, reduce the IV infusion to 0.5 g/h.

If patellar reflexes are depressed and respiration is normal, withhold further doses of magnesium sulfate until the reflexes return and request magnesium level.

If there is concern about respiratory depression , stop magnesium, give oxygen by mask and give:

Calcium gluconate (10mL of 10% solution over 10 minutes)

ACOG TASK FORCE 2013

... For women with severe preeclampsia, the administration of intrapartum and postpartum magnesium sulfate to prevent eclampsia is recommended.  For women with preeclampsia undergoing cesarean delivery, the continued intraoperative administration of parenteral magnesium sulfate to prevent eclampsia is recommended.

ACUTE FATTY LIVER OF PREGNANCY : ANESTHESIA IMPLICATIONS

Presentation : Any pregnant patient in the late second or third trimester who has elevated liver enzyme levels, especially in the presence of hypoglycemia. Also if patient presents with altered mental status and altered liver function in the postpartum period.

Preop optimisation : early recognition of liver dysfunction and aggressive resuscitation and treatment of hypoglycemia, DIC, and other associated complications.

Check the drug chart of the patient.  Avoid / reduce dose of medications with substantial hepatic metabolism to prevent worsening encephalopathy

Consider reversal agents if the patient has received narcotics (ie, morphine)

If cesarean section is required, coagulopathy and thrombocytopenia should be corrected before surgery when possible

Anesthetist should be prepared for massive blood loss (eg, 2 large-bore intravenous catheters, blood products in room, fluid warmer and level 1 transfuser available, arterial line, and central line available).

Choice of anesthesia:
General anaesthesia may worsen or confuse the clinical appearance of encephalopathy.  Regional techniques, however, may not be appropriate in those patients with worsening coagulation, and waiting for correction of any coagulopathy could lead to further deterioration in clinical condition.  Regional anaesthesia can also cause hypotension and decrease hepatic blood flow.

If epidural analgesia is used for vaginal delivery, the epidural should be left in place until correction of coagulopathy.

High index of suspicion for epidural hematoma should be maintained :
Hourly neurological examinations and early surgical consultation should be made if deficits are identified.

Anaesthesia for Myelomeningocele Repair; Precautions to be taken

Associated conditions: Hydrocephalus, Chiari II malformation, neurogenic bladder/ bowel, short trachea (Take care to avoid endobronchial intubation)hydronephrosis, malrotation of the gut, VSD, ASD, Craniofacial anomalies (Screen for these in first 24 hours after birth, before taking for surgery; may need ECHO, Renal US) Latex allergy is increased in this population Check electrolytes, RFT

Goals of the surgery: Preservation of neural tissue, reconstituion of a normal intrathecal environment, complete skin closure to prevent CSF leak and meningitis. Concern: Most MMCs leak CSF from time of birth--> risk of ventriculitis--> hence closure is recommended within 48-72 hours after birth

Points to ponder:

Take care in prone position to avoid undue pressure over body parts..facial oedema can occur postoperatively

Warmer should be arranged to avoid hypothermia; control the O.R. temperature

Before induction, protect the back defect with sterile donut or rolls

 In case of large defects local or myocutaneous flaps may be required to close the defect adequately 

Progressive hydrocephalus establishes after closure of MMC

The efficacy of intrauterine meningomyelocoel repair is being explored 

Anticipate lower brainstem dysfunction 

Need for blood replacement is rare in straight forward cases (EBL ~25 mL)

Usual duration: 1.5-3 hours

If complex repair with fascial release and tight abdomen: better to ventilate for first 24 hours; otherwise on-table extubation can be done

Postoperatively, child is usually nursed on stomach or side; head circumference and head USG are used to monitor for progressive HCP, which may require VP shunt

Post operative complications: wound infection, CSF leak, renal failure, respiratory compromise from tight abdomen

Respiratory complications : hypoventilation, sleep apnoea, bronchospasm, laryngospasm, prolonged breath holding as a result of structural derangement of  medullary respiratory control

Cardiovascular complications: bradycardia, hypotension and tachycardia. Brainstem compression and coning causes most of the  cardiac complications including cardiac arrest when Chiari malformation is  associated with MMC.

Delayed recovery has to be anticipated...so arrange for postop ventilation ( Respiratory centre dysfunction, due to brainstem compression, if there, will again, increase the chance of requirement for post op ventilation) 

Check for swallowing, gag reflex before extubation. Extubation should be performed only when the child is awake and breathing well.

Pain score 3-5

DIAGNOSIS OF AMNIOTIC FLUID EMBOLISM

Lower mortality can be achieved (27-37%), when early duagnosis made, and aggressive treatment implemented

Typical : Patient healthy prior to the onset of symptoms

ONSET: During or within 30 mins of labor ,cs ,dilatation and evacuation

Most important features :
DYSPNOEA-HYPOTENSION-DIC

OTHERS: Foetal distress, Seizures, Pulmonary edema, Uterine atony, Bronchospasm, Transient hypertension, Cough, Headache

Pneumoperitonium and CVP

".. Anesthesia and the Trendelenburg position increased the CVP, PCWP and pulmonary arterial pressures and decreased cardiac output. Pneumoperitoneum increased these pressures further mostly in the beginning of the laparoscopy, and cardiac output decreased towards the end of the laparoscopy. The risk of systemic CO2-embolus was increased during laparoscopy."

Ref: Acta Anaesthesiol Scand. 1995 Oct;39(7):949-55.

Femur fractures and expected blood loss

SURGERIES AND BLOOD LOSS

Displaced # NOF: Hemiarthroplasty
Undisplaced # : Closed Reduction n Percutaneous Pinning
Intertrochanteric #,Sub trochanteric #: Dynamic Hip Screw
Shaft#: Intra Medullary Nailing

Expected bloodloss

Undisplaced..<100 ml
Displaced...250-500
Intertrochanteric 500+
Distal femur,shaft,im nail 750+