General surgery. Thyroid surgery. Physiological response to pneumoperitoneum. Bowel resection

Transcription

1 General surgery Thyroid surgery Physiological response to pneumoperitoneum Bowel resection General surgery 3.D.9.1 James Mitchell (December 24, 2003)

2 Thyroid surgery Preoperative Assessment Routine, plus Thyrotoxicosis symptoms Anxiety, tremor, heat intolerance, fatigue, weight loss TFT, Ca 2+, FBE, U&E, ECG, CXR, CT if indicated Complications Goitre, atrial fibrillation, SVC obstruction Airway compromise, stridor, tracheomalacia Eye complications of Graves disease Treatment Antithyroid drugs, radioactive iodine Complications of therapy: marrow suppression Other therapy: ß-blockers Determine fitness for surgery Euthyroid, little risk of thyroid storm Airway and vascular compromise determined and manageable Preparation, premedication, transport Routine Intraoperative Monitoring, access Routine Induction Routine relaxant technique Tube placement commonly armoured tube with circuit over head Care with positioning, secure connections, eye protection Positioning Supine with shoulder roll Maintenance Balanced technique, IPPV Poor access to head and airway Emergence Request from surgeon to check vocal cord movement Often will not change surgical management Requires deep extubation when reversed and laryngoscopy Postoperative Airway distress Upper airway obstruction due to soft tissues and reduced muscle tone Laryngospasm, bilateral cord paralysis Inadequate reversal Wound haematoma Laryngeal oedema Tracheomalacia Anaphylaxis Hypocalcaemia due to hypoparathyroidism May be early (1-3 hours), more commonly 1-3 days General surgery 3.D.9.2 James Mitchell (December 24, 2003)

3 Physiological response to pneumoperitoneum Intraabdominal pressure cmh 2 O CVS Venous pooling in legs, IVC compression RVR, venous return vascular resistance of intraabdominal organs SVR Respiratory compliance, intrathoracic pressure on IPPV Neuroendocrine ADH, catecholamines, renin, angiotensin II sympathetic tone Net effect CO, MAP Minimized by filling, head-down position, α 2 -agonists Regional effects Venous stasis in legs DVT PCO 2 causes vasodilation if ventilation is not increased ( ICP) Arrhythmia: bradycardia due to peritoneal manipulation General surgery 3.D.9.3 James Mitchell (December 24, 2003)

4 Bowel Resection Preop PREOPERATIVE CONSIDERATIONS Two major patient groups: young inflammatory bowel disease (IBD) and older cancer resections IBD patients typically slim, otherwise well, may be on long-term corticosteroids and opioids Cancer patients may have anemia, hypercoagulability, hepatic dysfunction from metastases, electrolyte disturbance from secretory adenocarcinomas Bowel preparation may cause dehydration, electrolyte disturbance PHYSICAL FINDINGS Signs of bowel obstruction if present WORKUP Investigation of usual comorbidites in old patients Preoperative investigations as indicated: hematology, electrolytes, liver function, coags Crossmatch CHOICE OF ANESTHESIA General anesthesia. Rapid sequence induction indicated in obstructed patients. Additional epidural anesthesia and post-op analgesia supported by literature: less opioid use, faster wakeup, earlier return of bowel function, diminished inflammatory response, protection against DVT, better respiratory function. Contraindicated in patients with sepsis or coagulopathy. Test prior to induction. Intraop MONITORS/LINE PLACEMENT Potential for substantial bleeding, third-space loss of fluids Large IVs, arterial line, central line, temperature monitor indicated Otherwise routine monitoring: ECG, SpO2, gas analysis Surgeon will commonly request nasogastric tube INTRAOPERATIVE CONCERNS Positioning, particularly if in lithotomy for perineal approach Fluid shifts Heat loss Usual concerns with stress of surgery in older patients INTRAOPERATIVE THERAPIES Fluid management guided by CVP, urine output, observed blood loss, duration of surgery. Fluid balance often positive several liters on paper Active warming of upper body (and legs if possible) Postop POSTOPERATIVE PAIN Epidural dilute local anesthetic plus fentanyl by infusion usually provides good analgesia COMPLICATIONS Anastomotic leak may require reoperation Respiratory, cardiac or renal complications in elderly Surgical Procedure General surgery 3.D.9.4 James Mitchell (December 24, 2003)

5 INDICATIONS Bowel cancer Inflammatory bowel disease refractory to medical management Non-malignant disease causing obstruction Ischemic or non-viable bowel PROCEDURE Laparotomy with resection of affected bowel and its mesentery If anal canal or rectum is to be resected, perineal approach is often required as well Primary anastomosis commonly performed. Two or three stage procedures with temporary or permanent stomas are sometimes required. SURGICAL CONCERNS Dissection in pelvis for low anterior resections may be difficult TYPICAL EBL Highly variable General surgery 3.D.9.5 James Mitchell (December 24, 2003)