Medical Emergencies Study Guide for the CEN

Different Types of Shock

There are four different types of shock: hypovolemic, distributive, cardiogenic, and obstructive shock. In all types of shock, hypotension leads to poor tissue perfusion, resulting organ dysfunction, and inadequate removal of cellular waste. The definitions of the different types of shock are as follows:

Hypovolemic shock occurs when there is low circulating blood volume, usually due to trauma, surgery, extreme dehydration due to nausea or vomiting, or childbirth. Preload is decreased, cardiac output is decreased, and systemic vascular resistance is increased. It is classified by the percentage of total fluid loss:
- Class I: <750 mL or 15% of total circulating volume (TCV)
- Class II: 750-1500 mL or 15-30% of TCV
- Class III: 1500-2000 mL or 30-40% of TCV
- Class IV: >2000 mL or >40% of TCV
Distributive shock occurs when fluid leaks from the blood vessels and capillaries into the surrounding tissues from causes such as sepsis, anaphylaxis, or a spinal cord injury. Preload is decreased, cardiac output is increased, and systemic vascular resistance is decreased.
Cardiogenic shock occurs when there is damage to the heart resulting in diminished cardiac output from a myocardial infarction, congestive heart failure, cardiomyopathy, or a sustained cardiac arrhythmia. Preload is increased, cardiac output is decreased, and systemic vascular resistance is increased.
Obstructive shock occurs when blood flow to or from the heart is blocked due to causes such as pericardial tamponade, pneumothorax, or pulmonary embolism. Preload is decreased, cardiac output is decreased, and systemic vascular resistance is increased.

Assessment

Patients experiencing shock (regardless of the type) will demonstrate the following symptoms:

systolic BP <90 and/or MAP <65. Systolic BP can be <110 if the patient is initially hypertensive
altered mental status
decreased urinary output (less than 30 mL/hr or 0.5 mL/kg/hr)
cool, clammy skin and diminished peripheral pulses or dusky extremities
metabolic acidosis

Shock is compensated when the patient’s body can adjust to the beginning symptoms of shock. For instance, the patient may become tachycardic as their heart rate increases to maintain cardiac output but remain normotensive because the total cardiac output is unchanged. The shock becomes uncompensated when the patient’s physiological compensatory measures begin to fail, hypotension develops, and perfusion worsens. Irreversible shock becomes so severe that irreversible organ damage occurs due to poor perfusion, leading to multisystem organ failure and eventual death.

Lab work drawn in the event of shock includes:

CBC with differential
CMP
lactic acid
arterial blood gas
coagulation studies
ECG and echocardiogram if the suspected cause is cardiogenic
type and cross if the patient requires packed red blood cells or other blood products

Treatment

The treatment for shock involves stabilizing the patient’s condition and then treating the underlying cause. Ensure that the patient’s blood pressure is sufficient to maintain circulation to their vital organs and maintain a MAP of at least 65. Remember to perform fluid resuscitation prior to initiating vasopressors. Large bore peripheral IV access should be obtained immediately and a central line should be inserted as soon as is practical. If the patient is septic, a broad-spectrum antibiotic should be initiated as soon as blood cultures are drawn. Here’s a quick rundown of how to treat the different types of shock:

hemorrhagic shock—Administer isotonic crystalloid fluid boluses (usually 4-6 liters). If the patient is hemorrhaging, they should receive packed red blood cells, fresh frozen plasma, and platelets. Depending on facility policy, a Mass Transfusion Protocol (MTP) may be initiated if the patient receives more than 6 blood products in a 1-1-1 ratio. Any hemorrhage should be controlled immediately with surgical intervention if needed as well. Supplemental oxygen and even ventilation or intubation is sometimes needed. Vasopressors such as dopamine and norepinephrine can also treat hypotension.
distributive shock—Administer rapid fluid resuscitation with isotonic crystalloid to 2-3 liters total. Initiate broad-spectrum IV antibiotics if the patient appears septic. Administer epinephrine and possibly methylprednisolone (to prevent biphasic anaphylaxis) if the patient is anaphylactic. Vasoconstrictors and inotropic agents (dopamine, dobutamine, norepinephrine) should be initiated if fluid alone is ineffective in treating hypotension. Atropine can correct bradycardia in neurogenic shock.
cardiogenic shock—Administer fluids judiciously but avoid fluid overload. Inotropic agents like dopamine, dobutamine, and milrinone help to increase cardiac contractility. Apply oxygen to decrease the work of breathing. Nitroglycerin helps to decrease systemic vascular resistance. Insert an intra-aortic balloon pump (IABP) to increase cardiac output if medications alone are ineffective. Address the underlying cause. The patient may require heart catheterization with stents, coronary artery bypass grafting, or eventual heart transplant if they meet the requirements. Initiate heparin to reduce the risk of blood clots in some patients.
obstructive shock—Administer fluid judiciously, avoid fluid overload, and apply oxygen to decrease work of breathing. Immediately address the underlying cause of the obstruction. Treat a pneumothorax with a needle decompression and then chest tube insertion if needed. Remove a thrombus with a thrombectomy and/or initiate heparin. Norepinephrine can be initiated if the patient’s hypotension does not resolve with treatment of the underlying cause, and vasopressin can be added if norepinephrine alone is ineffective.

Substance Use Disorder, Dependence and Overdose

Substance use disorder is a mental health disorder that involves a patient using a medication or substance not as prescribed or illegally and develops a physical and mental dependence on it that makes it difficult or impossible to stop. Some of the most commonly abused substances are opioids, alcohol, and marijuana. Many drugs that are purchased without a prescription or illegally are laced with fentanyl, which increases the risk of overdose and addiction. Patients are unaware in many instances that the substances they are using contain fentanyl and they need to be educated about the risk. Unintentional overdoses can occur as the patient needs larger and larger doses to obtain the same effect.

Assessment

Symptoms of substance use disorder are as follows:

needing to take the substance in larger doses and more frequently for the desired effect such as pain relief
taking more than prescribed doses (if substance is prescribed)
having a strong desire to use the substance
facing difficulties in managing responsibilities with family or at work
focusing on obtaining the substance or becoming irritable when it is not available
worsening relationships with friends and family
withdrawing from daily activities
financial difficulties due to spending money obtaining the substance

Physical symptoms fall into two groups: patients who are actively intoxicated and those who are withdrawing. Patients who are intoxicated may be calm and sleepy or agitated and excited; they may be delusional as well or have visual or auditory hallucinations. Patients who are withdrawing can experience nausea and vomiting, diarrhea, muscle cramping, sensitivity to sound and light, sweating, and insomnia. Factors such as mental illness, history of childhood trauma or abuse, poverty, family history of addiction, and homelessness increase the risk of substance use disorder. Patients who have overdosed will be difficult to arouse or unresponsive, even to painful stimuli; have depressed or absent respirations; become bradycardic; and have pinpoint pupils if the overdose was due to narcotics.

There are no physical tests to definitively diagnose substance use disorder. Urine and blood drug screens can reveal the presence of a wide variety of drugs and alcohol that have been taken in the last day or two. Hair tests can reveal if a patient has used specific substances in the preceding months. A complete metabolic panel can be useful to evaluate if a patient’s substance use has adversely affected certain organs (such as alcohol and the liver) and ECG to determine if there are any underlying arrhythmias.

Treatment

Narcotic overdoses are treated with naloxone (Narcan), which can be administered intravenously, intramuscularly, or intranasally. The narcotics often last longer than naloxone, which means that multiple doses are required and the patient must be monitored closely with continuous SPO2 and ideally etCO2 monitoring. Patients who receive naloxone often become agitated and aggressive upon arousal. Flumazenil (Romazicon) is used to reverse benzodiazepines. The use of flumazenil can result in seizures, especially in patients who have used benzodiazepines long term.

There are many types of psychotherapy that are available to help the patient to manage their substance use disorder. Some of these types include cognitive behavior therapy, assertive community health treatment, therapeutic communities (inpatient treatment programs), contingency management, family therapy, motivational enhancement therapy, and dialectical behavior therapy. The efficacy varies depending on the patient’s preferences, health history, and personality. Substances such as suboxone are administered in a program with close monitoring and help the patient to avoid some of the unpleasant physical symptoms associated with drug and alcohol withdrawal while avoiding the intoxication. Other substances include buprenorphine, naltrexone, and methadone. Ensure that the patient has a good physical and emotional support system in place and secure housing, food, and income resources.

Be aware that it becomes more difficult to provide anesthesia and manage post-op/acute pain because the patient’s body is habituated to substances like opioids or marijuana. They will require larger dosages for effective pain management. Encourage clean needle use, keeping intranasal Narcan on hand, and being able to identify symptoms of overdose—don’t make people afraid to call 911 if they or their loved one have overdosed.

Withdrawal Syndrome

Withdrawing from alcohol and drugs (both prescribed and illegal) results in a number of unpleasant physical side effects and can cause life-threatening conditions. The difficult process makes it hard for many patients to stop, even if they want to stop. Many patients will need to be admitted to the hospital to receive medical care during the withdrawal process to stabilize their physical health and reduce the burden on their families.

Assessment

Symptoms of withdrawal include muscle cramps, confusion, tremors, visual and auditory hallucinations, sensitivity to light and sound, loss of appetite, nausea and vomiting, diarrhea, depression, anxiety, hypertension, tachycardia, paranoia, agitation, seizures, and dilated pupils. Urine and blood drug and alcohol screens will reveal from which substance(s) the patient is withdrawing and allow treatment to be directed appropriately. A CBC, CMP, and ECG will help to evaluate any underlying conditions that may be exacerbated by the physiological stress of withdrawal syndrome.

Several different scales are used to evaluate the severity of the patient’s withdrawal syndrome. The Withdrawal Assessment Tool-1 (WAT-1) and the Clinical Opioid Withdrawal Scale (COWS) are both used to grade the severity of opioid withdrawal symptoms. Alcohol withdrawal is commonly evaluated using the Clinical Institute Withdrawal Assessment for Alcohol (CIWA - A) and the Total Severity Assessment (TSA). The Clinical Institute Withdrawal Assessment for Benzodiazepines (CIWA-B) is used to grade the severity of benzodiazepine withdrawal.

Treatment

Many patients need to be hospitalized during the acute withdrawal process. Doing so allows close monitoring and treatment to relieve some of the symptoms/discomfort of withdrawal. If the withdrawal process becomes severe, the patient will sometimes need to be transferred to the ICU. In severe cases, the patient may need to be sedated and intubated for their own safety and to protect their airway.

The specific treatment protocol for withdrawal will vary from healthcare facility to healthcare facility. For alcohol withdrawal, Ativan is commonly administered on a sliding scale based on the patient’s CIWA score (the higher the score, the larger the dose of Ativan). Oral Ativan is usually administered unless the patient is NPO. If the withdrawal progresses to the point of requiring critical care, a one-time dose of phenobarbital is administered. Then IV phenobarbital will be administered, sometimes on a continuous infusion. Similar protocols and IV/IM antipsychotic medications, such as haloperidol, will be instituted for withdrawal from illegal drugs. Medications such as labetalol and hydralazine can be used to manage hypertension and tachycardia as needed.

In the cases of opioid or benzodiazepine withdrawal, the patient is ideally slowly weaned off their medication to avoid acute withdrawal symptoms. If the patient is unable to completely stop the opioid medications, buprenorphine and methadone doses can be initiated and titrated up according to the patient’s response once mild withdrawal symptoms begin. There is no known treatment for withdrawal from benzodiazepines. Flumazenil (Romazicon) helps to relieve some of the irritability and aggression associated with benzodiazepine withdrawal.