3.5 Management of anesthesia in shocked patient 

Anesthetic consideration of patient with clinical shock 

• Treat for shock as already outlined in the general and specific management tips. 
• Carefully assess the degree of hypovolemia. Unless the patient requires life-saving surgery it is beneficial to delay surgery while resuscitation is undertaken and hypovolemia, hypoxia and hypothermia treated. 
• Anesthetic management in shocked patient is heavily influenced by intravascular volume status and cardiovascular function. Sufficient preoperative systemic blood pressure (systolic B/P 90) is not indicative of adequate volume status, and therefore, heart rate, urine output, and mental status should all be considered when evaluating the volume. 
• Cross match blood and have it available for intra-operative use. 
• The presence of head and neck injuries, chest and abdominal injuries, must be ruled out in traumatic shock. 
• Use the IV route for any drugs given to the shocked patient. Drugs given IM are poorly absorbed. 
• Treat shocked patients as you would a patient with a full stomach i.e. rapid sequence induction with cricoid pressure. 
• Severely shocked patients may need ventilation after surgery. 
• Preparation for surgery includes having adequate blood products available and continuing antibiotic treatment. 
• Any vasopressors should be prepared and on hand before induction of anesthesia 

Premedication should be given intravenously, just before induction of anesthesia, so that a suitable dosage can be arrived. On account of respiratory depression, morphine may be contraindicated, atropine alone being usually sufficient. 

Induction 

• Anticipate full stomach from dysfunction of the gastrointestinal tract secondary to ischemia. A rapid sequence induction using small dose of anesthetic induction and suxamethonium is recommended. De-nitrogenation of the lungs, breathing 100% O2 through a tightly fitted facemask for up to 3 min, may be considered before induction of anesthesia. 
• A cuffed endotracheal tube is often desirable both to minimize the chance of aspiration of gastric contents and prevent under ventilation 
• Shocked and recently resuscitated patient requires much smaller amounts of anesthetic than relatively normal patients. Ketamine may prove useful for induction as it is unlikely to decrease systemic vascular resistance rapidly. 
• Options for the induction technique are many, including ketamine and etomidate (EXCEPT IN HYPOADRENAL SHOCK). Most I.V or inhalation anaesthetic agents cause vasodilation or impaired ventricular contractility. Induction of anesthesia is ideally a deliberate step-wise process, using small doses of I.V anaesthetic agents, titrated to clinical response. The choice of induction agent or narcotic is less important than the care with which they are administered. Ketamine or midazolam may provide a degree of hemodynamic stability and short acting opioids such as fentanyl will enable a reduction in the dose of anaesthetic induction agent. 

Maintenance and monitoring 

• Options for maintaining anesthesia include inhalation agents (reduced MAC), I.V. agents, and opioids (Fentanyl1μg/kg, pethedine .25mg-.5mg/kg) a combination of these in titration. The anesthetist should choose the technique which they believe best fits with their assessment of the individual patient‘s risk factors and co-morbidities, and their own experience and expertise. 
• Continued volume resuscitation and incremental doses of vasopressors are helpful to counteract the hypotensive effect of anesthetic agents and positive pressure mechanical ventilation. Options for the use of vasopressors include ephedrine, phenylephrine, and epinephrine. 
• Intraoperative monitoring may be facilitated by continuous monitoring of blood pressure, pulse rate, saturation, urine output, body temperature and peripheral perfusion (color and capillary refill). Given that carbon dioxide production may be amplified in septic patients, capnography should be used to adjust minute ventilation. 
• Intravenous fluid warmers and peripheral warming blankets may possibly aid in maintenance of temperature homeostasis. 
• Neuromuscular blocking drugs should preferably non-histamine releasing agents, e.g., Vecuronium and pancuronium. 
• Oxygenation may be impaired by non-cardiogenic pulmonary edema, which is caused by the increased capillary permeability in sepsis. Management options for hypoxemia during maintenance of anesthesia include increasing the inspired oxygen concentration and incrementally increasing PEEP (Positive end expiratory pressure). 

Postoperative care 

• Postoperative management includes constant monitoring of vital signs. 
• Mechanical ventilation is often continued after surgery especially when dealing with persistent hemodynamic instability or if it is necessary to maintain adequate circulation with inotropic support