Pelvic Exentoration: The Anesthetic Aspects - Term Paper Example

PELVIC EXENTERATION AND ANESTHETIC ASPECTS Definition Surgical procedure involving exploration and removal of organs in the central pelvis alongwith their attachments is known as pelvic exenteration. The procedure includes: 1. Removal of lower part of the colon, rectum, bladder and reproductive organs in the pelvis. 2 .Construction of a new bladder using ileum (ileal conduit), directing the ureters into it and connecting it to the abdominal wall so that urine is drained out. The urine can be drained either by intermittent catheterization or by continuous connection to a pouch outside the abdominal wall. 3. Colostomy to drain faeces outside the body. 4. Vaginal reconstruction using skin, intestinal tissue and myocutaneous graft. Indications for pelvic exenteration: Primary: 1. Centrally recurrent cervical cancers in patients who have received definitive radiotherapy. 2. Any recurrent pelvic tumor (endometrial carcinoma, ovarian tumor, vaginal cancer, aggressive prostate cancer or rectal cancer), if a chance of cure exists with the procedure. Secondary: Palliative procedure for control of local disease causing severe fistulas or other unmanageable symptoms. Contraindications Absolute contraindications for this surgery are disease extending in to the pelvic wall, skip metastasis and peritoneal metastasis, while metastasis to retro-peritoneal lymph nodes is a relative contraindication. Liver cancer, extra pelvic disease, obstruction of urinary tract, inflammation of roots of spinal nerves, sciatica and lymphedema are contraindications to any pelvic surgery. Types of pelvic exenteration: 1. Anterior exenteration: female reproductive organs (in women), bladder, and prostate (in men) are removed. It is indicated in cancers which allow rectum to be spared. For urinary diversion, ileal conduit is constructed. In women, vaginal reconstruction is undertaken during the procedure or at a later date. 2. Posterior exenteration: reproductive organs and lower part of the bowel are removed. The bladder and urethra are intact. For the exit of stools, colostomy is done. 3. Total exenteration: all reproductive organs (male and female), rectum, anus, lower colon, bladder, urethra and their supporting muscles and ligaments are removed. Ileal conduit and colostomy are also done. Vaginal reconstruction is done at a later date. Risk factors Pelvic exenteration remains a gold standard in the surgical management of advanced pelvic malignancy. The success of the operation lies in correct patient selection and supportive peri -operative care. It is important to know about risk factors because; almost every patient who undergoes this surgery develops at least one complication. 40 to 50% of the patients experience major complications and the operative mortality is 2 to 5%. Age more than 65 years is an obvious risk factor due to decreased cardiac reserve and ability for tissue repair. Previous pelvic irradiation appears to be a major risk factor (35% vs. 7.5%) for anastomotic breakdown and fistulas, independent of the presence of a protective colostomy (Mirhashemi, R, 2000). Associated health problems like cardio-pulmonary diseases, obesity, diabetes mellitus, hypertension and liver disease also contribute to morbidity. Complications Intra-operative: Arrhythmias, cardiac arrest, blood loss, hypothermia, etc. Early post-op: Blood loss, sepsis, wound dehiscence, anastomotic break down at the level of the bowel, urinary pouch or ureteral sites and injury to the bowel. Late post-op: UV fistula, bowel obstruction, ureteral strictures, renal failure, pyelonephritis, chronic bowel obstruction, intra abdominal abscesses and chronic renal failure. These occur in 1/3rd of the patients. Other complications: Pneumonia, ARDS, hydronephrosis, vaginal cuff cellulitis and urinary incontinence in women, acute and chronic rectal dysfunction, peroneal nerve compression and obturator nerve transection. Complication rates 45% of the patients suffer from complications between the first day and 7 months. About 24% suffer from minor complications while the rest suffer from major complications (Lobaton, 1996) Population affected Pelvic exenteration is most commonly done as a salvage procedure in women with recurrent cervical cancer. 9 lakh cases of cervical cancer occur every year world wide (Verschraegen, 2004). The incidence is influenced by geographic variations. It ranges from 4 - 45 per one lakh women. 80% are reported from the developing country (due to lack of effective screening). Survival rates The 5-yesr survival rates vary from 23% to 61%. The most common recurrence is in the pelvis. Poor prognostic factors associated with recurrence are tumor size > 3cm., pelvic side wall or resection margin involvement, nodal metastasis and time interval less than one year from prior radiation treatment. Anesthetic aspects of the procedure Before surgery, it is important to assess the patient’s condition thoroughly and optimize it. Hydration and hemoglobin must be taken care of because, blood loss and fluid derangements occur during the procedure. Prophylactic antibiotics must be started prior to surgery and must be continued during surgery. Anesthetic complications can be minimized by perioperative haemodynamic stability with the help of adequate remote monitoring, early and fast transfusion, temperature control and multidisciplinary communication. The choice of anesthesia can differ based on the patient condition, extent of exenteration, institution policy and other health conditions. The surgery can be done under general, spinal or epidural anesthesia. Of course, general anesthesia can be used alone or with a combination of spinal or epidural. Often combining a regional technique with general anesthesia decreases the amount general anesthesia needed. If an epidural line is placed, continue it for post-op pain management. If only regional anesthesia and no general anesthesia is used, light sleep must be induced with IV sedation. Duration of surgery Based on the type and extent of exenteration and the allied surgeries like ileal conduit, colostomy and vaginal reconstruction, the duration of surgery can vary from 7 to 20 hours. Blood loss and replacement The hemorrhage in pelvic exenteration is mainly from sacral venous plexus. The approximate blood loss during surgery is estimated to be about 1.2 liters. A study by Lopez in 2003 estimated blood loss in pelvic exenteration between 750 ml to 4250 ml (average 1500ml). Some of them may not require blood transfusion at all, even post-op. But most of need blood transfusion during and after surgery. Fresh whole blood should be used for replacing blood loss.In case of severe bleeding during surgery from the plexus, surgical packs may help. Also, drains may be inserted during surgery for post-op estimation of blood loss. These drains must be kept only if necessary because they can get colonized easily and become a source of infection. Fluid management This is the most important aspect in perioperative management. Fluids in the form of blood, crystalloids and colloids must be given during and after surgery. Use of Swan Ganz catheter helps in managing fluid and volume status by providing an accurate assessment of left ventricular end diastolic pressure. The complication rate is reported as 5% and consists mostly of ruptured balloons, infection, coiling of the catheter, and cardiac irritability (Partridge, 1979). Also, slow infusion of IV albumin (25%) during the first 16 hours after surgery is a better approach to fluid management post-op (Yared, 2000). Patients who are thus managed have a more stable postoperative course with less fluid boluses, fewer electrolyte bolus requirements and easier management of blood pressure and urine out put. Also, this stable course helps early initiation of central hyper alimentation (Fiorica, 1991) and helps fast recovery. Hypothermia Hypothermia during surgery is of concern because it can contribute to cardiac ischemia, arrhythmias, increased blood loss, coagulopathy, wound infection, decreased drug metabolism and prolonged hospitalization. Hypothermia occurs due to disordered thermoregulation due to anesthetic drugs, IV fluids and blood transfusion. Blood loss itself may contribute to decreased core temperature. Hypothermia can be prevented by warming IV fluids and blood prior to administration (using blood warmer- to 37 deg. C). Forced air convective warmer used during and immediate post-op is an effective method of tackling hypothermia (Stoneham, 2000; Jackson, 1997)). A warmer blanket may be necessary during surgery. Reducing the time span between induction of anesthesia and completion of surgery helps to maintain core temperature. IV lines must be inserted before induction. Pain management Post operative pain contributes to cardiac ischemia, infection, delayed recovery and prolonged hospital stay. Immediate post-op pain must be managed with effective analgesics, preferably using combination drugs. Epidural bupivacaine along with IV tramadol has been found to be effective in managing post-op for abdominal and pelvic surgeries (Aribogan, 2003). After immediate post op, simple analgesics like tramadol and ketorlac can be used for pain relief. After this phase, NSAIDs are effective in decreasing pain. Mild sedatives along with analgesics decrease the dosage of analgesic. Bibliography Aribogan, A. (2003) "Patient-controlled epidural analgesia after major urologic surgeries. A comparison of tramadol with or without bupivacaine." Urologia Internationalis., 71, no. 2, 168-75 Fiorica, J.V., Roberts, W.S., Hoffman, M.S., Barton, D.P., Finan, M.A., Lyman, G., Cavanagh, D.(Dec.1991). "Concentrated albumin infusion as an aid to postoperative recovery after pelvic exenteration." Gynecol Oncol., 43(3), 265-9. Husain, A. “Pelvic exenteration.: Retrieved on 5/31/2007 from http://www.emedicine.com/med/topic3332.htm. Jackson, S.A.,& Clinton, C.W.(Aug.1997). "Postoperative management of hypothermia of intra-operative origin--experience with a forced-air convective warming device." S Afr J Surg., 35(3).134-8. Lobaton, A.T., Mendoza, R.L., Bassure. E. R, Aten, D. & Herrera, G. R. (Dec.1996). “Current status of frequency and complications of recurrent cervica-uterine cancer after radiation”. Gynecol. Obstet. Mex., 64, 538-43. Lopez, J.M.& Perez, L.M. (2004). “Composite Pelvic Exenteration- Is it worthwhile?” Annals of Surgical Oncology, 11(1), 27-33. Mirhashemi, R., Averette, H.E., Estape, R., Angioli,R., Mahran,R.& Luis, M.,et al.(December 2000) "colorectal anastomosis after radical pelvic surgery: A risk factor analysis." American Journal of Obstetrics & Gynecology. ,183(6):1375-1380. Partridge, E.E., Beasley, W.E., Holcomb, C., Hatch ,K.D., Shingleton, H.M. & Austin, J.M. Jr. (Feb.1979) "The Swan-Ganz catheter and management of patients undergoing pelvic exenteration." Obstet Gynecol, 53(2).253-5. Pinelo, S., Petiz, A., Domingues, C., Lopes, C., Alves, A.& Fael, R. (Mar-Apr 2006). “Pelvic exenterations for gynaecological cancer--a 10 year institutional review” Acta Med Port.,19(2), 99-104 Shepherd,J.H., Ngan,H.Y.S.,Neven,p.,Fryatt,I., Woodhouse,C.R.J & Hendry, W.F. (1994). “Multivariate analysis of factors affecting survival in pelvic exenteration.” International Journal of Gynecological Cancer, 4 (6), 361–370. 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