Critical Care

Overview• Damage Control• Resuscitation from Shock• Traumatic Brain Injury• Pulmonary System and Ventilators• Cardiovascular System• Renal System and Electrolytes• Hematologic System• Gastrointestinal System and Nutrition• Immune System and Infections• Endocrine System• Musculoskeletal System• Preparation for Evacuation

Damage Control

• Damage Control is the initial control of hemorrhage and contamination followed by intraperitoneal packing and rapid closure.

• Definitive re-exploration is then done only after resuscitation to normal physiology in the ICU

• May include– Rewarming– Large volume resuscitation– Blood products– Vasoactive drugs– Mechanical ventilation

Resuscitation from Shock

• Shock: acute state of cardiovascular insufficiency leading to hypoperfusion

• Hemorrhagic shock is the most common cause of shock in the trauma patient

• Hypoperfusion implies inadequate tissue delivery to the tissues. Oxygen delivery depends on (and resuscitation attempts should address):– Cardiac function– Arterial hemoglobin content– Arterial oxygen saturation

Resuscitation from Shock

• Resuscitation Goals:– Mean arterial pressure >60mmHg– Urine output >0.5cc/kg/hr– O2 saturation >92%

• Achieve these goals with crystalloid (preferred over colloid) at a rate of 500-1000cc every 15-20 minutes as needed

• After 3L crystalloid, blood products should be given• Vasoactive agents should be considered only after fluid

resuscitation and confirmation of adequate intravascular volume– Prefer dopamine, phenylephrine, norepinephrine– Dobutamine should be used only for cardiac dysfunction

Traumatic Brain Injury

• Hypoxemia or hypotension can lead to death or poor neurologic damage in the traumatic brain injury patient– Maintain O2 sat >92%, PaO2 > 100, intubate if GCS <8– Maintain SBP > 100 mmHg, MAP >80

• Need to maintain cerebral perfusion pressure (CPP) between 70-90mmHg

• Need to maintain intracranial pressure (ICP) between 5-15mmHg

• CPP = MAP - ICP

Traumatic Brain Injury

• Hypoxemia or hypotension can lead to death or poor neurologic damage in the traumatic brain injury patient– Maintain O2 sat >92%, PaO2 > 100, intubate if GCS <8– Maintain SBP > 100 mmHg, MAP >80

• Need to maintain cerebral perfusion pressure (CPP) between 70-90mmHg

• CPP = MAP - ICP• Need to avoid intracranial hypertension. Maintain

intracranial pressure (ICP) between 5-15mmHg

Traumatic Brain Injury

• Measures to avoid intracranial hypertension– Elevate head of bed to 30◦– Check serum sodium twice per day and maintain between 145-

150 mEq/dL– IV mannitol 0.25-1.0 g/kg every 6-8 hours to keep serum

osmolarity optimal (but not in anuric patients)– Control PaCO2 (avoid hypercarbia by therapeutic

hyperventilation to keep PaCO2 30-35mmHg)– Avoid hyperthermia– Intraventricular catheter to remove cerebrospinal fluid– May consider barbiturates in extreme cases (benefit unproven)– Craniotomy as a last resort

Traumatic Brain I jury

• General Considerations– Prophylaxis (H2 blocker, heparin) to prevent stress ulcers and

venous thrombosis– Oral care to prevent aspiration– Blood products as needed to correct elevated prothrombin

time– Aggressively treat pain, agitation, fever, and shivering to avoid

increased cerebral metabolism and oxygen consumption– Hyperglycemia has an adverse effect. Maintain serum glucose

betwee 100-150 mg/dL– Seizure prophylaxis with phenytoin or phosphenytoin should

be given to patients with penetrating head injuries

Pulmonary System and Ventilators

• Indications for intubation– Airway obstruction due to trauma, edema, excess

secretions– Apnea– Increased work of breathing– Glasgow coma scale <8– Hypoxia despite supplemental oxygen: SaO2< 90%,

PaO2 < 60mmHg– Hypercarbia: PaCO2 >60mmHg– Shock

Pulmonary System and Ventilators

• Ventilator– Most patients well ventilated by SIMV mode

(synchronized intermittent mandatory ventilation)– Oxygenation

• Set FiO2 to 1.0 initially and wean down to 0.4 as able• Set PEEP to 5 cm H2O for most patients or can increase if

needed (max 15 cm H2O)

– Ventilation (controls PaCO2)• Set tidal volume between 6-10 mL/kg (increase if need to lower

PaCO2, decrease if need to raise PaCO2)• Set rate between 10-14 breaths (increase if need to lower

PaCO2, decrease if need to raise PaCO2)

Pulmonary System and Ventilators• ARDS (adult respiratory distress syndrome) defined by:

– PaO2/FiO2 ratio <200– Decline in pulmonary compliance (“stiff lungs”)– Bilateral alveolar infiltrates on chest X-ray withouth clinical evidence

of hypervolemia• Ventilation priorities in ARDS

– Maintain sedation to prevent agitation and patient/ventilator asynchrony

– Keep SaO2 > 90% by increasing FiO2 or PEEP (max 15-18 cm H2O)– Avoid prolonged FiO2 > 60% (oxygen toxicity)– Avoid respiratory acidosis (keep pH > 7.25)– Keep peak inspiratory pressure < 40 cm H2O (decrease tidal volume to

6-8 cc/kg)

Cardiovascular System

• Causes of cardiovascular instability (the H’s and T’s)– H’s:

• Hypoxia• Hemorrhage• Hypovolemia• Hyper- or Hypo- kalemia• H+ (acidosis)

– T’s• Tension pneumothorax• Tachyarrhythmia• Thromboembolism• Tamponade• Toxins

Cardiovascular System

• Four measures of hemodynamic performance– Preload: Best measured by pulmonary capillary

wedge pressure (PCWP) but can be estimated by central venous pressure (CVP)

– Afterload: Systemic Vascular Resitance (SVR) = [MAP – CVP]/CO*80

– Heart rate: Stroke Volume (SV = CO/HR)– Contractility

Cardiovascular System

• Myocardial Infarction: uncommon on the battlefield• Suspect if soldier complains of anginal chest pain• Diagnose by ST elevation or depression on EKG, elevation in

cardiac enzymes (troponin, CK-MB)• Treatment:

– Morphine– Oxygen – Nitroglycerin– Aspirin– B-blocker– Transfer for definitive treatment (revascularization by thrombolytic

or catheterization)

Renal System and Electrolytes

• Manifestations of renal injury/failure: low urine output, electrolyte abnormalities, elevations in BUN or creatinine

• Acute renal failure (ARF) defined as oliguria ( < 0.5 cc/kg/hr) and rise in BUN and creatinine

• Common causes of ARF:– Hypovolemia– Acute tubular necrosis (ATN)– Crush injury resulting in rhabdomyolysis– Renal or ureteral trauma

Renal System and Electrolytes

• Treatment algorithm for oliguria or anuria in hemodynamically stable patient– Irrigate or replace Foley catheter– If no signs of fluid overload, give 1-2L saline bolus– Review medication list and discontinue any potential nephrotoxins– Check fractional excretion of sodium (FeNa)

• FeNa =(urine sodium * plasma creatinine)/(plasma sodium * urine creatinine)

• FeNa < 1.0 indicates hypovolemia, > 2 indicates renal or postrenal insult (ATN, obstructive uropathy, etc)

– Consider renal U/S• If ineffective, consider dialysis.

Renal System and Electrolytes

• Indications for dialysis (Nemonic = AEIOU)– A: acidosis– E: electrolytes– I: ingestions– O: overload (Hypervolemia)– U: uremia

Renal System and Electrolytes

• Hyperkalemia– Give calcium carbonate to stabilize the cardiac

membrane– Agents that lower serum potassium

• Sodium bicarbonate• Dextrose• Albuterol• Sodium polystyrene sulfonate

• Hypokalemia– Check for hypomagnesemia and correct if present– Give potassium chloride

Renal System and Electrolytes

• Hypernatremia: Need to replace free water deficit– Free water deficit = 0.6 * weight in kg * [(measured

sodium/normal sodium of 140) – 1]– Replace half of the deficit in the first 24 hours, the other

half over the next 1-2 days• Hyponatremia: caused by excess of free water or

SIADH (syndrome of inappropriate anti-diuretic hormone)– Treatment with either free water restriction if suspect

SIADH, otherwise treat by administration of saline– Do not correct faster than 15mEq/L in 24 hours

Renal System and Electrolytes

• Hypophosphatemia: replete with sodium phosphate or potassium phosphate

• Hyperphosphatemia: Usually associated with acute renal failure. Treat with phosphate binders such as sucralfate

• Hypomagnesemia: Give magnesium sulfate to achieve serum level of 2.0 mEq/dL

Renal System and Electrolytes

• Metabolic acidosis: Usually due to lactic acidosis (hypovolemia) or ketoacidosis (diabetic). Do not give sodium bicarbonate for these conditions, treat the underlying cause.

• Metabolic alkalosis: Caused by gastric losses (vomiting or NG suction) or excessive diuresis with furosemide. Usually treated with crystalloid.

Hematologic System

• Coagulopathy– Causes: dilutional, heparin induced

thrombocytopenia, disseminated intravascular coagulation, hypothermia, liver failure, thrombocytopenia

– Treatment: blood products• Deep venous thrombosis and pulmonary

embolism: Prophylaxis important in trauma patients (subcutaneous heparin and/or sequential compression devices)

Gastrointestinal System and Nutrition

• Stress gastritis: give prophylaxis with H2 blocker or proton pump inhibitor for the following conditions– Burns– Mechanical ventilation– Head injury– Sepsis– Systemic anticoagulation

• Acalculous cholecystitis– Suspect if right upper quadrant pain, fever, leukocytosis, liver function test

abnormalities, and ultrasound with thickened gallbladder wall and/or pericholecystic fluid

– Treatment = IV antibiotics and percutaneous drainage or surgery• Hepatic failure

– Suspect if hyperbilirubinemia, hypoalbuminemia, increased prothrombin time, hypoglycemia, obtundation (hepatic encephalopathy)

– Give fresh frozen plasma to correct coagulopathy

Gastrointestinal System and Nutrition

• Early nutritional support important due to catabolism and protein wasting associated with trauma

• Enteral feeding superior to parenteral• Caloric requirements = 25-30 kcal/kg/day• Protein requirement 1.0-1.5 g/kg/day• 30-40% of daily caloric intake should come from fat• Problems associated with enteral feedings include aspiration and

diarrhea. Prevent by:– Increasing head of bed– Feed into jejunum or duodenum instead of stomach– Check residuals every 4 hours and stop feedings if >200cc– Add fiber and/or give anti-diarrheal medications such as loperamide

Immune System and Infections• Differential diagnosis of ICU infection:

– Pneumonia– Central venous catheter infection– UTI– Wound or soft tissue infection– Intra-abdominal abscess– Systemic fungal infection– Sinusitis– Acalculous cholecystitis– Pancreatitis

• Prophylactic antibiotics: – Should be given for 24-48 hours after penetrating battlefield injury– Should be discontinued after this unless documented infection present

Endocrine System

• Hyperglycemia:– Must control to prevent hypovolemia due to

osmotic diuresis, increased risk of infection, etc.– This is best done with IV infusion of insulin as

subcutaneous injections are less reliable in ICU patients

– Do not correct faster than 100 mg/dL/hr to avoid to avoid hypokalemia (insulin causes potassium to shift intracellularly). Check K+ frequently and replete as needed

Musculoskeletal System

• In patients with musculoskeletal injuries, monitor for the following:– Rhabdomyolysis– Compartment syndrome– Vascular ischemia

• Regular neurovascular checks essential. Check for:– Pulse, sensation, motor function, warmth, skin

color

Preparation for Evacuation

• Stabilize patient before transport– Secure airway– Ensure blood pressure has been stable for 8 hours– Complete primary and secondary phases of shock

resuscitation– Stop bleeding– Ensure definitive surgery not required for next 24

hours