Conference Lectures

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A Gangrene bowel and septic shock for emergency laparotomy

Dr. A. Sahoo
HOD Anesthesia &Critical care, 
BokaroGeneral Hospital,
BokaroSteel City. Jharkhand

INTRODUCTION
Gangrene bowel and septic shock is a life threatening condition, require immediate resuscitation and surgical intervention. It is a major health problem affecting all age groups throughout the world. Gangrene bowel in which parts of the intestine lose their blood supply and die due to intestinal obstruction. Commonest causes are postoperative adhesions and hernia.Surgical interventions are needed urgently otherwise patient may develop septic shock.The initial hours or(golden hours) of clinical management of gangrene bowel and septic shock represent an important opportunity to reduce morbidity and mortality. Anesthetist play a central role in the multidisciplinary management of the patient from their initial deterioration at ward level,transfer to the diagnostic imaging suite and intra-operative management for emergency surgery. Rapid clinical assessment,resuscitation and surgical management by focused multidisciplinary team, and early effective antimicrobial therapy are the key components to improved patient outcome.

Causes of Gangrenous bowel:-
It can occur in large and small intestine. 80% of the obstruction occurs in small intestine. Gangrene bowel occurs in older than 50. In adults it is usually the result of ischemic bowl disease. Gangrenous bowel can also occur in infants and younger children who have bowel obstruction.
Common causes of ischemic bowel disease that result in gangrene includes :-

  • Strangulated hernia
  • Twisting in any parts of the intestine
  • Blood clots
  • Tumors

 

Pathophysiology:-

                           
Normally approximately 7-9 liters fluids are secreted daily in upper gastrointestinal tract. The secretions include saliva(500-2000ml), gastric juice(1000-2000ml), bile(300-600ml), pancreatic juice(300-800m)and succusentericus(2000-4000ml). Because of small intestine reabsorption, only 400 ml passes the ileo-coecal valve. In gangrenous bowel all these fluids are collected proximal to the obstruction. Because of edema and inflammation, absorption decreases, sequestration of fluids from the circulation into the lumen occurs. Approximately 4-6 liters of sequestrated fluidsare collected in 24 hours.

Bacteria,(E.coli, klabsiella,anaerobes, bacteroids and other organisms) multiply and release endotoxins. Accumulation of bactreialtoxins,bile salts, prostaglandins,  mucosa derived free radicals, VIP all these increases  the luminal secretions causing dilatation of the bowel wall,it increases intra-luminal pressure which exceeds the bowl wall venous pressure which causing ischemia which further causes dilatation and ischemic injury.These leads to  blockade of arterial perfusion causing bowel wall necrosis /gangrene.
Increase bacterial colony in the bowl, due to altered luminal contents and environment→ multiplication→ toxins→ further mucosa damage→disrupted mucosal defense/barrier/integrity→translocation of bacteria across mucosa into sub-mucosa and also absorption of bacteria and toxins to the circulation → bacterimia/toxemia→septicemia→ severe sepsis→septic shock→MODS.

  • Secondary changes in other organs:-
  • Cardiovascular :-diminished venous return due to decrease circulatory volume leads to decrease cardiac output, hypotension, decrease in oxygen transport leads to poor oxygenation of tissueleading to metabolic acidosis and it further decrease cardiac function.
  • Renal:- these are secondary to hypovolemia,fall in cardiac output, increase secretion of ADH and aldosterone.It decrease GFR and renal insufficiency enhance metabolic acidosis.
  • Respiratory:-Abdominal distension due to ileus, together with restriction of diaphragmatic and intercostals movement due to pain result in fall in tidal volume. This predispose to atelectasis, which result in ventilation perfusion mismatch and a fall in partial pressure of oxygen in blood.

 

 

Anesthetic management:-
A.Quick restoration of circulatory hemodynamics.
B.Useof appropriate antibiotics.
C.Critical support of different organ system.
D.Maintenance of ventilation.
Initially resuscitate the patient by assessment of airway, breathing and circulation. Then conduct the secondary assessment of patient including a thorough history, detailed examination of the system and appropriate investigations.

  • Hemodynamic resuscitation :-

                                           The objective of preoperative resuscitation is to rapidly restore adequate oxygen delivery to peripheral tissues.Most patients are hypovolumic from massive sequestration of fluid into the peritoneum and lumen of gut. So early hemodynamic optimization before development of organ failure reduces mortality by 23%. In septic patients other than vital parameters, invasive arterial pressure monitoring and ICU or high dependence unit admission must be considered. Placement of central venous catheter will allow measurement of CVP, administration of IV fluids and vasopressures. Intravenous infusion of normal saline, dextrose saline and ringer lactate should be given to raise the CVP, the filling pressure of the ventricles and the cardiac output. Too rapid infusion in the patient with overt cardiac disease can cause pulmonary edema. Over resuscitation of shock can cause hypervolumia and should be avoided as this can precipitate  ARDS. Vasopressure support with nor-epinephrine may be considered even before optimal IVF loading has been achieved. Low dose vasopressin(0.03unit/min) may be added to reduce the requirement of high dose nor-epinephrine alone. Ionotropes are added to volume resuscitation and vasopressure, if there is evidence of continued low cardiac output despite adequate cardiac filling and fluid resuscitation. The surviving sepsis campaign recommends that Dobutamine is the first line ionotrope therapy to be added to vasopressure in septic patients in the presence of myocardial dysfunction and ongoing signs of hypoperfusion. 
Abnormalities in electrolyte balance and acid base balance should be corrected. Hemoglobin should be raised by packed red cells infusion and kept close to 11 gm/dl. Derranged coagulation profile should be corrected by infusion of fresh frozen plasma. Input/output charting should be carefully monitored.Supplemental oxygen therapy is valuable in severely septic patients even if they don’t have signs of respiratory distress.

  • Antibiotic therapy:-

                      Empirical therapy should be started promptly after relevant culturehas been sent. Usually within one hour of diagnosis of sepsis as every hour delay in antibiotics increases mortality. Therapeutic concentration of effective antimicrobial agent should be maintained throughout the peri-operative period as the procedure itself may cause further bacteremia and clinical deterioration.

  • Intra-operative management:-

                                         The primary role of anesthesiologist during intra-operative period is to provide safe and optimal care. Insertion of naso-gastric tube and urinary catheterization should be done before induction. General anesthesia with endotracheal intubation and control ventilation is the technique of choice. De-nitrogenation of the lungs, breathing 100% oxygen through a face mask should be considered before induction of anesthesia. Options for induction drugs include Ketamine,Etomidate,slow administration of Propofol and titrated dose of Thiopentone sodium. Most intravenous or inhalational anesthetic agents cause vasodilatation or impair ventricular contractility, so induction of anesthesia should be a stepwise process using small incremental doses titrated to clinical response. Short acting opioids such as fentanyl, alfentanyl or remifentanylwill enable in reduction the dose of anesthetic induction agent. A rapid sequence induction of anesthesia by using succinylcholine to facilitate tracheal intubation may be required.If hyperkalemia or any other contraindication to succinylcholine, Rocuronium can be employed to facilitating neuromuscular relaxation. Continued volume resuscitation and vasopressure infusion are helpful to counteract the hypotensive effect of anesthetic agents. Special care should be taken to maintain normothermia, fluid, electrolyte, acid base balance and urine output.

  • Maintainence of anesthesia:-

                                         Anesthesiologist should choose the technique which they believe fits with their assessment of individual patient risk factors and co-morbidities and their own experience and expertise. During surgery the hemodynamic state may be further complicated by blood loss or systemic release of bacteria and endotoxins. Transfusion of blood product should proceed without delay if the surgical procedure is complicated by excessive blood loss. Whatever technique is used, the depth of anesthesia achieved can be estimated using bi-spectral index monitoring. Intravascular volume resuscitation should be continued throughout the surgical procedure. As per SSC guidelines hemodynamic goal should be – CVP 8-10 cm of H2O, MAP > 65 mm of Hg, urine output 0.5 mlkg-1hr-1, central venous oxygen saturation  >70%, hematocrit  >30% and lactate <2mmol litre-1.

  • End of surgical procedure:-

                                     At the conclusion of surgical procedure, administration of further neuromuscular blocking agents to facilitate surgical closure of the abdomen may be considered. The rate of blood loss should be minimal before leaving the operating theatre. Safe transfer of patients to the ICU is essential. A focused handover report is helpful for ICU colleague which highlights the clinical presentation, response to resuscitation measure, antimicrobial agent used, details of the surgical procedure performed, blood product used intra-operatively and any specific problems that should be anticipated in the post-operative period.

  • Post-operative management in ICU:-

                                            Pre-resuscitation measure should be used to calculate the intensive care admission APACHE score and not those that have improved after resuscitation. Having secured the patient’s airway, mechanical ventilation setting can be decided with the objective of minimizing ventilator induced volutrauma and barotraumas to the lungs. Low tidal volume, high fractioned inspired oxygen concentration, permissive hypercapnia may be considered provide that arterial pH doesn’t decrease below 7.2. Attention should be given to fluid, electrolytes, acid base balance and to nutrition is vital.It’s important that antimicrobial therapy which was started before operation, should be continue in the ICU and the time of next schedule should be noted. Antimicrobial regimen reassessed daily and adjusted to ensure efficacy and to avoid toxicity. Fresh-frozen plasma may be used to correct laboratory clotting abnormalities if there is clinical bleeding. Deep vein thrombosis prophylaxis should be considered. Adequate glycemic control(<8.5 mmollitre-1) isimportant in the control of septic process. In a large, international, randomized trial of ICU patients, there was no significant difference between strict glycemic control (blood glucose 4-6 mmollitre-1) and more liberal glycemic control (blood glucose 6-10 mmollitre-1). Therefore, in severly septic patient, blood glucose should be maintain in the range 6-10 mmollitre-1. Nutrition is one of the corner-stone of management in gangrene bowl and septic shock patients and total parentral` nutrition is indicated. The use of low dose glucocorticoids(hydrocortisone) 50mg four times daily where normovolemic septic patients seen refractory to vassopressor therapy to maintain major organ perfusion and hemodynamic stability. Acute renal failure occurs in 23% of patients with severe sepsis. Renal replacement therapy may be initiated to correct acidosis, hyperkalemia or fluid overload should be continued until acute tubular necrosis has been recovered. Continuous renal replacement therapy may be more practical in hemodynamically unstable patients.

  • Conclusion:-

                Gangrene bowel and septic shock is the most common surgical emergency with high   morbidity and mortality. The anesthesiologist has a crucial role in co-ordinating in delivery of resuscitation and therapeutic strategies to optimize patient’s survival and outcome.
References :

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