Chapter 2: Resuscitation and Stabilization

Resuscitation—reanimation in many languages—is the restoration of life where it is absent or diminished. Resuscitation is the simultaneous identification and treatment of threats to life, limb, or function and is initiated by any qualified person whenever and wherever such a threat is recognized.

The need for resuscitation may announce itself with obvious signs such as a patient struggling to breathe or speak, by dramatic alterations in mental status, or by abnormal vital signs, but may also be manifested by more subtle markers of serious illness such as singed nasal hair, muffled voice, or a mottled extremity.

We will first describe a stepwise approach to the initial phase of resuscitation of the undifferentiated, critically ill patient—the primary survey—and then more comprehensively discuss the basic assessments, maneuvers, and strategies central to any resuscitation paradigm.

The goal of the first 5 minutes of resuscitation is to establish the conditions in which resuscitation can be effectively carried out, identify the most immediate life threats, and initiate stabilizing therapies (Table 2–1). The acronym used here is DC3A-J:

• D: Danger

  The first priority in resuscitation is to determine that it is safe to approach the patient; the first D stands for Danger—danger to the provider and the treatment team. This preliminary step assumes much greater importance in the prehospital environment than the operating theater, but all patients pose a potential threat to their treating clinicians. Scene security (from fire, armed aggressors, etc) is a clear priority in the field. In all settings, appropriate personal protective equipment to shield against bloodborne or airborne infectious disease is essential. Occasional patients will have a dangerous substance on their skin or clothes and require decontamination.

  The agitated patient deserves special consideration. In addition to the potential for violence against providers, which by itself would indicate appropriate chemical and physical restraint as an early priority, agitated patients can be broadly divided into two groups. In many cases, agitation can be confidently attributed to benign etiologies such as psychiatric disease or safe intoxicants; these patients can be managed in a measured, methodical fashion using de-escalation techniques or titrated chemical or physical restraints. Agitation, however, can either accompany or be caused by life-threatening disease, and in these cases the patient interfering with their care becomes an additional threat to their own safety. When sufficient concern for a dangerous condition exists, agitated patients must be immediately controlled using assertive doses of powerful sedatives; we prefer ketamine, droperidol, and/or midazolam.¹

• C: Call for help

  Verify at the outset of care that the patient is in the appropriate location, and that the appropriate personnel and equipment are either at bedside or summoned. This may mean activating emergency medical service (EMS), activating an in-house critical patient alert, or pushing the patient to another area in the department.

• C: Calm

  An important impediment to optimal patient care is apprehension and the resuscitationist's own anxiety level should be actively managed. An early step to take in this regard is to make a loud room quiet. This can be accomplished with a forceful quiet please and by requesting that observers not directly participating in patient care move to the perimeter or out of the room altogether. This maneuver also establishes the resuscitation leader, which if not apparent should be done at this point.

  In medical resuscitation, operator catecholamines generally rise in response to anxiety around the patient deteriorating despite efforts, or in anticipation of an infrequently performed procedure. An effective technique to combat this anxiety and lower catecholamines is to consider how the patient could deteriorate and decide, in as much detail as achievable, how to respond. Invisible simulation of this sort can be augmented if necessary by tactical breathing¹ where relaxation physiology is harnessed to effect calm, which allows optimal decision making.

• C: Cardiac arrest

  Cardiac arrest must be recognized immediately, and may be missed in unresponsive or intubated patients unless specifically sought. In patients who are unresponsive to a painful stimulus and not certainly breathing (gasping can occur in arrest or just prior to arrest) or intubated patients, the first consideration is to establish the presence or absence of a pulse. This can be accomplished by palpation, a pulse oximetry waveform, or cardiac ultrasound.

  As soon as pulselessness is detected, chest compressions are initiated, then the rhythm is established so that ventricular fibrillation and ventricular tachycardia may be defibrillated. While the search for the cause of arrest is ongoing, supportive therapies such as vasopressors and empiric treatment of relevant reversible causes of cardiac arrest are often provided; the establishment of vascular access is therefore an early priority in most scenarios, using an intraosseous cannula if venous access is not quickly obtained. This is the time to consider placing large-bore femoral cannulae if intra-arrest extracorporeal membrane oxygenation (ECMO) is available.

• A: Airway

  The goal of the airway assessment in the primary survey is to determine if an airway intervention is needed now or in the near term. Patients with dynamic airway lesions such as neck trauma, anaphylaxis, angioedema, and thermal or caustic inhalational injury demand a high level of vigilance and preparation for definitive airway management, even without signs of airway compromise. These bullets, bites and burns lesions can cause rapid deterioration of airway patency and escalation of difficulty in airway management. Otherwise, a patient who is able to speak comfortably with a clear voice is unlikely to require an immediate airway intervention.

  The four signs of airway embarrassment are change in voice, stridor, mishandling of secretions, and airway posturing. Many patients who require resuscitation have decreased level of consciousness and demonstrate a patent, defended airway by handling their secretions: Drooling, gurgling, coughing, gagging, or sonorous respirations indicate the potential for an unprotected airway.

  The airway interventions to consider in the primary survey include head and neck positioning (including jaw thrust), suctioning of oral secretions, removal of a foreign body, placement of oral or nasal airways, placement of a laryngeal mask airway, or endotracheal intubation.

• B: Breathing

  The primary breathing assessment focuses on the adequacy of oxygenation and the provision of therapies to augment oxygenation when needed. In an alert patient, breathing competence is best assessed by respiratory effort; distress is indicated by high respiratory rate, recruitment of accessory muscles, and speaking in less than complete sentences. Pulse oximetry—especially room air pulse oximetry—is a reliable indicator of respiratory status in awake or obtunded patients, provided a good waveform is present. Auscultation of the lungs should be performed briefly, with the intent of identifying bilateral breath sounds, wheezes, and crackles.

  Supplemental oxygen is the cardinal empiric therapy for breathing disorders. All critically ill patients should be placed on nasal cannula oxygen, which can be augmented with face mask oxygen or noninvasive ventilation (continuous positive airway pressure [CPAP]/bilevel positive airway pressure [BiPAP]) depending on the oxygenation deficit and its suspected etiology.

  Other therapies to consider in the primary survey include nebulized albuterol for reactive airway disease, nitroglycerine for pulmonary edema, and thoracostomy (with needle, chest tube, or finger) for an unstable patient with pneumothorax. A portable chest radiograph may be called for when indicated.

• C: Circulation

  The initial assessment of circulation centers on the adequacy of organ perfusion, as evidenced by mentation and warm, dry skin with brisk capillary refill. Heart rate and blood pressure are measured, usually by placing the patient on a telemetry monitor. The presence of gross jugular venous distention should be sought, as it indicates heart failure/volume overload or circulatory obstruction.

  Resuscitative vascular access is an early, crucial priority. In the non-exsanguinating critically ill patient, prompt placement of a short, large-gauge catheter into a peripheral vein is usually sufficient for initiating the first phase of treatment. The patient with life-threatening hemorrhage requires an additional high-flow cannula—either a 16-gauge or larger angiocath or a 7-Fr or larger introducer placed in a large peripheral or central vein—to facilitate transfusion at the outset of care. If intravenous access is unable to be obtained immediately, an intraosseous catheter should be inserted without delay.

  The most important therapies to support circulation to consider in the primary survey are crystalloid and blood. Epinephrine is indicated in the primary survey when anaphylaxis is a high concern.

  An electrocardiogram (ECG) may be obtained in the primary survey when the patient is suspected to be critically ill from an arrhythmia or acute coronary syndrome. Unstable tachycardias are shocked and unstable bradycardias are paced at this juncture unless an immediately reversible cause is identified. Perhaps the most important of these is hyperkalemia, which is common and dangerous enough that calcium therapy should be specifically considered in the primary survey, especially in renal failure patients.

• D: neurologic Disability

  The initial evaluation of neurologic disability is four maneuvers: assessment of level of consciousness and mentation; pupillary size, symmetry, and reactivity; movement at four extremities; and capillary glucose measurement.

  Level of consciousness is adequately des-cribed in the primary survey as either agitated, alert, responsive to verbal stimuli, responsive to painful stimuli, or unresponsive to painful stimuli. Agitation or confusion can be as ominous as obtundation as a marker of serious disease.

  All patients with neurologic signs should have hypoglycemia either excluded or empirically treated. Signs of brain herniation may be treated straightaway with mannitol or hypertonic saline. Early brain imaging is appropriate in patients thought to be critically ill from a structural brain lesion.

• E: Exposure

  Patients who require resuscitation should have all clothing removed and every inch of skin examined as early as can be done safely. Evidence of trauma, rashes, medication patches, medical alert tags, scars, and medical devices often direct care and are easily missed unless sought. If the history is incomplete, clothing and possessions should be inspected for clues.

  A rectal temperature can be taken at this time, and active warming or cooling is initiated in the primary survey when indicated.

• F: Family and friends

  Many patients who require resuscitation cannot provide a complete history, making the collateral history offered by EMS, family, companions, or other providers crucial. Goals of care should be clarified or established early, when appropriate. In cardiac arrest, offer family the opportunity to be present during the resuscitation. Otherwise, provide an early report to the family, erring on the side of cautious prognosis. Language like I'm very concerned usually appropriately sets expectations and conveys a suitable degree of uncertainty.

• G: analGesia

  Pain should be rapidly, aggressively treated as a primary goal of care but also to reduce catecholamine release. Intravenous opiates are first line in most cases: Fentanyl offers rapid onset of action and is an excellent initial choice, followed by longer-acting agents such as morphine or hydromorphone. Analgesic-dose ketamine (0.15 mg/kg) is an effective alternative or addition when opiates are ineffective or not desired.³ Intramuscular or subcutaneous dosing should be provided to the patient in severe pain if intravascular access is not immediately available.

• H: Human chorionic gonadotropin

  Pregnancy may be occult and usually changes the trajectory of resuscitation; it must be specifically considered early in the care of any ill woman of childbearing age. This is most easily accomplished by placing two drops of blood on a standard urine human chorionic gonadotropin (hCG) cassette assay.⁴

  The uterus of the hypotensive late trimester patient should be manually displaced to the left. A woman who presents arrested or nearly arrested with a gravid abdomen should be considered for perimortem caesarean section.

• I: Infection

  Isolation of patients who may have dangerous communicable illness is an essential step when indicated. Patients thought to be critically ill from an infection should have appropriate cultures drawn and promptly treated with broad-spectrum antibiotics. Early source control, such as the removal of an infected catheter or surgical debridement of infected tissue, may be lifesaving and should be initiated as rapidly as practicable.

• J: ultrasound Jel

  Point-of-care sonography is indicated early in the management of all patients with hypotension of uncertain etiology to narrow the differential diagnosis, guide procedures such as vascular access, and direct fluid resuscitation. Specific ultrasound techniques will be highlighted in the following sections.

Emergency Airway Management

The Decision to Intubate

Endotracheal intubation (ETI) is the most dangerous procedure that most resuscitationists routinely perform. While performing ETI on a patient who would have done well without it is suboptimal, delaying or omitting ETI when it is required is much more likely to result in patient harm. Understanding the indications for intubation is therefore a cardinal skill for providers who care for the critically ill; these are summarized in Table 2–2.

Anatomic airway lesions—especially dynamic airway lesions mentioned earlier—can progress rapidly and demand a particularly aggressive, early airway strategy that also accounts for their expected difficulty. Disorders of breathing are the most common reason for ETI in most environments but are also the most treatable with noninvasive ventilation, as discussed later. Failure to protect the airway from neurologic disability is classically confirmed by the absence of a gag reflex, but this is no longer considered good practice because a significant portion of the population has a poor gag reflex, and performing an emetogenic stimulus on a patient with compromised airway defenses is dangerous.⁵

Preparation for Endotracheal Intubation

In optimal airway management technique, preparation is deliberate and meticulous, while the procedure itself is brief and anticlimactic. Preparation is divided into preoxygenation, cognitive readiness, and material readiness. In addition to complex decision making, ETI requires many simple steps that, when accidentally omitted, can bring disaster; we therefore strongly recommend using a checklist (Figure 2–1).

Preoxygenation should start as soon as the decision to intubate is made. In addition to large-volume oxygenation techniques, all patients should be oxygenated with a nasal cannula, which augments conventional maneuvers and provides positive pressure oxygenation during the airway attempt, prolonging safe apnea time.⁶ Most patients can be fully preoxygenated with a reservoir face mask. Patients who do not saturate better than 95% with a non-rebreathing face mask likely have a physiologic shunt and will quickly desaturate during the airway attempt; preoxygenation is in these cases therefore ideally done with noninvasive ventilation.⁷ Patients whose respiratory effort is insufficient to oxygenate with high-flow supplemental oxygen should have respirations assisted by bagging across a face mask or via a supraglottic airway device.

Patients who are too agitated to allow adequate oxygenation are more safely managed by using dissociative sedation to facilitate oxygenation. Delayed sequence intubation calls for the administration of induction-dose ketamine (1 mg/kg IV over 30 seconds with additional doses of 0.5 mg/kg as needed), followed by closely monitored application of usual preoxygenation technique, followed by the administration of a paralytic and commencement of the airway attempt.⁸

Cognitive readiness entails assessment of the patient's physiology and difficult airway features to develop an airway strategy that includes a specific plan for failure of intubation and failure of ventilation; the roles of all team members should be clearly defined at this stage. Material readiness stipulates that all equipment that may be needed for initial and failed airway management is either at bedside or is located and quickly available.

Airway Strategy

Most patients are best intubated using rapid sequence intubation (RSI), the simultaneous administration of an induction agent and paralytic, followed by laryngoscopy. Through paralysis, RSI immediately provides optimal intubating conditions and reduces the likelihood of aspiration. RSI also renders the patient apneic, however, and ventilation must be established before critical desaturation occurs. RSI therefore may not be the best choice when laryngoscopy is predicted to be difficult or when maneuvers to rescue failed laryngoscopy—bag mask ventilation and cricothyrotomy—are expected to be difficult (Table 2–3).

The most important alternative to RSI is awake intubation, which uses local anesthesia and systemic sedation to facilitate laryngoscopy while spontaneous respirations are preserved. The more difficult the airway features and the less procedural urgency, the more likely awake intubation should be used instead of RSI.

Laryngoscopy

Direct and video-assisted laryngoscopy are the chief airway management techniques in most resuscitation environments. Video laryngoscope devices that utilize a standard geometry (eg, Macintosh) blade offer the advantages of video laryngoscopy (better view of the glottis, viewable by others who can thus advise or assist) as well as the advantages of direct laryngoscopy (easier tube delivery, no soiling of camera). For either direct or video laryngoscopy, the patient should be optimally positioned with the external auditory meatus parallel to the suprasternal notch; in obese patients this often means building a “ramp” of sheets under upper back, shoulders, neck, and head. Inclining the torso 15° to 45°, either by raising the head of the bed or using reverse Trendelenburg position, improves glottic view and oxygenation as well as reducing the likelihood of regurgitation or emesis, and should be used routinely but especially in obese or vomiting/hematemesis patients.^9,10

The laryngoscope of either a direct or video device should be inserted into the mouth under direct vision. Once the blade has controlled the tongue, gaze may be shifted to the video monitor. The first goal is to visualize the epiglottis; once identified, the blade is positioned to lift the epiglottis and expose the vocal cords. If an adequate view of the glottis is obtained, the endotracheal tube may be delivered at this point—if using video, advance the tube under direct vision until the tip of the tube approaches the end of the blade, then return gaze to the screen. Inadequate views may be enhanced by an assistant performing jaw thrust, repositioning of the head, or external manipulation of the larynx.¹¹ Poor glottic views may be intubated using a gum elastic bougie; we recommend using the bougie routinely so that its advantages may be skillfully leveraged in difficult airway scenarios.

As soon as these maneuvers have failed to produce an intubatable view of the glottis, or significant desaturation has occurred, laryngoscopy should be aborted and ventilation established. Bag mask ventilation is more likely to be effective and less likely to dangerously insufflate the stomach if nasal and oral airways are placed and the mask is applied to the face with two hands, the Ambu bag compressed by an assistant. Alternatively, when laryngoscopy has failed, immediate ventilation through a supraglottic airway device is both easier and more effective than bag mask ventilation.

Once ventilation is established and the patient is reoxygenated, the equipment, modality, patient position, or operator is changed and another airway attempt is undertaken. If after failed intubation ventilation and oxygenation also fail, it is imperative that a surgical airway be initiated early, before critical desaturation.

Postintubation Management

After tracheal position is confirmed by capnography, supracarinal position is confirmed by auscultation of both lungs. The tube is secured and postintubation analgesia and sedation are initiated. In the just-intubated patient, it is appropriate to provide aggressive sedation, as the patient may still be paralyzed and require invasive procedures or transport. Once the patient has settled and is stable on the ventilator, sedation should be lightened to a more physiologic level of arousal.

Noninvasive Ventilation

Noninvasive ventilation (NIV, variously referred to as noninvasive positive pressure ventilation [NIPPV], CPAP or BiPAP]) uses a ventilator attached to a tight-fitting mask that covers the nose or both the mouth and nose to deliver oxygen at positive pressure. NIV has emerged as a valuable therapy in the management of various types of respiratory failure. In particular, the care of patients with pulmonary edema, decompensated chronic obstructive pulmonary disease (COPD), and severe asthma has been transformed by the application of NIV in resuscitation environments. To realize the potential of NIV to reduce the incidence of ETI and its attendant morbidity, all equipment and expertise needed to initiate NIV must be present at the point of care, that is, clinicians are able (and encouraged) to initiate NIV without summoning assistance or materials from outside the department.

Arrested patients require invasive ventilation techniques, and full face mask NIV should not be used if vomiting is a high concern, however most other patients with respiratory failure of any type deserve a trial of NIV, if only as preoxygenation while preparations are being made for ETI. NIV is appropriate for use in patients with noncurative goals of care,¹² and has an emerging role in supporting ventilation during procedures that require deep sedation or analgesia.¹³

Hypotension

Along with airway and breathing embarrassment, the management of patients with circulatory compromise, as evidenced by hypotension and/or hypoperfusion, is a foundational charge of the resuscitationist. Empiric therapies to support circulation are instituted in the primary survey as the differential diagnosis—perhaps the most important in resuscitation medicine—is considered (Table 2–4).

Bedside Sonography for Hypotension

Goal-directed point-of-care ultrasound has assumed a central role in the management of patients with undifferentiated hypoperfusion states. Bedside sonography can be quickly performed in the resuscitation bay simultaneously with other maneuvers, is noninvasive, repeatable, and powerfully enhances the diagnostic power of the history and physical examination.¹⁴

The evaluation of traumatic hypotension was among the earliest indications for nonradiologist-performed ultrasound.¹⁵ Focused Assessment with Sonography for Trauma (FAST) entails a series of targeted ultrasound windows (Table 2–5) to rule in common causes of hypotension in blunt or penetrating trauma. FAST has reduced computed tomography (CT) use, marginalized invasive diagnostic peritoneal lavage (DPL), and improved patient-oriented outcomes in the management of trauma.¹⁶

Bedside sonography is of high utility in both the diagnosis and management of atraumatic hypotension. The Rapid Ultrasound for Shock and Hypotension (RUSH) examination outlines a goal-directed algorithm¹⁷ which has been supplemented with additional assessments since its inception to produce a comprehensive evaluation of the hypoperfused patient.¹⁸

Focused echocardiography is often of great value in hypotension. The parasternal long-axis view is generally used to identify pericardial effusion and, if present, to assess for diastolic collapse of the right atrium and ventricle, suggesting tamponade physiology. The apical four-chamber view can be used to assess for right ventricular dilation and paradoxical motion of the interventricular septum; this is evidence of pulmonary hypertension, raising the specter of pulmonary embolism as the etiology of hypotension.¹⁹ Left ventricular contractility, qualitatively assessed in parasternal long or short axis, is classified as hyperdynamic (as seen in hypovolemia), normal, or depressed (seen in coronary ischemia, cardiomyopathy, or myocardial depression from sepsis). Left ventricle (LV) function may also be used to guide the administration of IV fluids and vasoactive drugs.

Respirophasic variation in diameter of the inferior vena cava (IVC), as measured by bedside sonography, has been shown to correlate with central venous pressure and intravascular volume, and may predict fluid responsiveness.²⁰ The IVC is readily assessed in its longitudinal axis and measured 2 cm from its entrance into the right atrium; the greater the variation in the diameter of the IVC with respiration, the more likely the patient is to benefit from fluid administration.

Lung ultrasound is used to exclude pneumothorax, as in trauma, by visualizing sliding of the visceral pleura on the parietal pleura with the linear array probe positioned at the third intercostal space, midclavicular line. Pulmonary edema is identified sonographically by the prevalence of hyperechoic vertical beam artifacts, B-lines, that arise at the interface of water and air. The presence of three or more B-lines per field indicates interstitial fluid and, together with LV and IVC assessment, can be used to predict fluid responsiveness (Figure 2–2).²¹

In appropriate circumstances, the abdomen is assessed for free fluid, as in the FAST examination, which in medical resuscitation could indicate bleeding or ascites. The aorta is imaged for aneurysm from its origin inferior to the xiphoid process to its iliac artery bifurcation point; diameter greater than 3 cm is abnormal with higher likelihood of rupture greater than 5 cm.

If pulmonary embolism is in the differential, bedside two-point compression sonography of the femoral and saphenous veins accurately detects deep vein thrombosis (DVT).²²

Lastly, ultrasound is used to guide resuscitative venous access, pericardiocentesis, paracentesis, chest drainage, and lumbar puncture, as well as determine endotracheal tube position.²³

Resuscitation Goals and Therapies in Hypotension

Blood pressure is the most basic proxy for tissue perfusion, and remains a valuable guide to therapy, with a mean arterial pressure (MAP) of 65 mm Hg often used as a target.²⁴ A more reliable indicator of successful resuscitation, however, is end-organ function. Normal mentation, urine output, and skin quality demonstrate adequate perfusion, though young, healthy patients have high physiologic reserve and may not manifest hypotension and organ failure despite significant perfusion deficit.

Serum lactic acid clearance has emerged as a powerful resuscitation barometer and predictor of patient outcome in a variety of shock states^25,26 and is recommended as a resuscitation goal by the Surviving Sepsis Campaign.²⁷ While treatment-resistant hyperlactatemia is an ominous sign demanding a diagnostic and therapeutic reevaluation, a significant proportion of decompensated, critically ill patients will have normal lactate levels.²⁸ Serum lactic acid—like all resuscitation parameters—should therefore be interpreted as a single data point in a larger clinical context.

Patients shocked by traumatic hemorrhage may benefit from lower blood pressure targets until bleeding is controlled.²⁹ Critically injured patients may benefit from titrating therapy to a sympatholytic blood pressure target, using fentanyl to attenuate catecholaminergic vasoconstriction.³⁰

The cardinal therapy for hypotension and shock is identification and treatment of its underlying cause. Empiric management often begins with intravenous fluids, with colloidal preparations such as albumin demonstrating no benefit over crystalloid in most studies.³¹ Normal saline or lactated Ringer solution are appropriate choices for initial fluid resuscitation; patients with high fluid requirements should be transitioned to more balanced solutions or fluid preparations tailored to their physiology.³² The utility of additional fluid and the relative balance of fluids and vasopressors in the individual hypotensive patient remains a central resuscitation challenge. The ideal test of fluid responsiveness demonstrates an augmentation of cardiac output with fluid challenge. When direct measurement of cardiac output is not feasible, a variety of surrogates have been used to predict and evaluate the benefit of volume (Table 2–6). Vasopressors are traditionally added when the patient is thought to be volume replete or fluid unresponsive; however, especially in distributive shock, earlier use of low-dose pressor infusions may be of benefit.³³ Although data are not definitive,³⁴ norepinephrine is often recommended as the first-line vasopressor in many shock states.²⁷

Blood products should be used sparingly in medical resuscitation. Current recommendations call for empiric packed red blood cell transfusion when hemoglobin levels fall below 7 g/dL,³⁵ though higher targets may be considered in coronary ischemia or if perfusion goals are not met despite optimization of other resuscitation parameters.³⁶ Conversely, hypoperfused trauma or hemorrhaging patients should receive little if any crystalloid in favor of warmed blood products, ideally as part of a transfusion protocol that balances red cells with platelets, plasma, cryoprecipitate, and calcium.³⁰ Most transfused trauma patients should also receive the procoagulant tranexamic acid,³⁷ and in critically bleeding patients underlying coagulopathy should be deliberately sought and treated with appropriate agents such prothrombin complex concentrate, desmopressin (ddAVP), and vitamin K.

Cardiac Arrest

The management of atraumatic cardiac arrest starts with the immediate provision of supportive therapies, followed by consideration of specific therapies to address the precipitating cause. After cardiac arrest has been identified, if resuscitation is consistent with the goals of care, the earliest priority is the initiation of chest compressions at a rate of at least 100 per minute, a depth of approximately 2 in, and allowing full recoil between compressions. If a chest compression device is not used, the compressor should be switched at regular, brief intervals to maintain quality. Chest compressions should proceed with minimal interruption until return of spontaneous circulation, implementation of extracorporeal life support, or pronouncement.

The determination of the cardiac rhythm and defibrillation of pulseless ventricular tachycardia or ventricular fibrillation should occur as early as feasible and at regular intervals thereafter. Vascular access is established with large-bore peripheral venous catheters or an intraosseous catheter. Ventilation may be initiated using a supraglottic device such as an laryngeal mask airway (LMA), to be replaced with an endotracheal tube if needed for gas exchange or definitive airway control. Most arrested patients should be ventilated with an explicitly low rate and volume, preferably using a mechanical ventilator. The empiric use of vasopressors and antidysrhythmics in cardiac arrest is recommended by widely adopted guidelines³⁸ and is routine in most environments. The use of specific intra-arrest therapies is guided by history, physical examination, and ultrasound (Table 2–7).

Continuous capnography should be initiated at the outset of cardiac arrest care to verify the efficacy of ventilation (through bag mask, supraglottic device, or endotracheal tube) and monitor intra-arrest care. End-tidal CO₂ (ETCO₂)reflects cardiac output and a drop in ETCO₂ often indicates chest compressor fatigue.³⁹ Return of spontaneous circulation is detected by a sudden rise in ETCO₂ and an ETCO₂ value persistently less than 10 mm Hg predicts failure of resuscitation.⁴⁰ When supportive therapies have been provided and reversible causes of cardiac arrest are considered and addressed, ongoing cardiac arrest predicts a poor likelihood of successful reanimation (in the absence of extracorporeal oxygenation).⁴¹ A low ETCO₂ value and the absence of sonographic cardiac contractility are often used as further evidence of poor recoverability and an appropriate point to terminate efforts and pronounce the patient as deceased.⁴²

Emerging therapies in intra-arrest care include extracorporeal oxygenation and transesophageal echocardiography (TEE). In capable centers, selected patients in cardiac arrest are stabilized with emergency department–based ECMO, which replaces cardiac and pulmonary function while the underlying lesion is addressed. Extracorporeal cardiopulmonary resuscitation requires specialized equipment, training, and a multidisciplinary protocol, but can produce remarkable rates of neurologically intact cardiac arrest survival.^43,44 Intra-arrest TEE provides anatomic windows to the heart and surrounding anatomy in detail not degraded by body habitus or lung disease, while allowing access to the chest for compressions and other procedures. TEE is more likely to identify the precipitant of arrest than TTE, provides real-time feedback on the adequacy of chest compressions, reveals electrocardiographically occult ventricular fibrillation, and distinguishes pulseless electrical activity from pseudo–pulseless electrical activity (PEA) (myocardial contractions too weak to generate a pulse).⁴⁵

When return of spontaneous circulation (ROSC) is achieved, patients who do not have return of mentation should be maintained at 36°C.⁴⁶ Further efforts to determine the arrest precipitant should be undertaken if uncertain and the patient considered for immediate coronary angiography.⁴⁷ Priorities in postarrest care include lung-protective ventilation with normoxia, inotropic and vasopressor agents to address hypocontractility and hypotension, careful attention to glucose and electrolytes, and optimization of end-organ perfusion.

External chest compressions and vasoactive medications do not benefit patients who arrest following trauma.^48,49 The management of traumatic arrest centers on prognostication based on mechanism, signs of life, and duration of cardiac arrest.⁵⁰ Appropriate patients should receive bilateral chest decompression and consideration for resuscitative thoracotomy, where pericardial tamponade is relieved and penetrating injuries to the heart or pulmonary vessels temporarily controlled, the aorta cross-clamped, and internal cardiac massage performed.⁵¹