Anesthetic management during mass casualty/disaster scenarios

INTRODUCTION — 

A mass casualty event (MCE) is an incident that may overwhelm medical resources if there are more injured patients than locally available health care resources can manage. Anesthesia clinicians are uniquely trained in advanced resuscitation and are often proficient at triage of patients requiring surgical procedures. This topic will review perioperative considerations for MCE scenarios, including patient resuscitation, triage to the operating room, and considerations for anesthetic care when limited resources are available.

Natural, chemical, biological, and radiation events that cause an MCE are reviewed in separate topics:

●(See "Severe crush injury in adults".)

●(See "Overview of the management of the severely burned patient".)

●(See "Electrical injuries and lightning strikes: Evaluation and management".)

●(See "Chemical terrorism: Rapid recognition and initial medical management".)

●(See "Management of radiation injury".)

Initial management and anesthetic considerations for adult trauma patients are reviewed separately. (See "Initial management of trauma in adults" and "Anesthesia for adult trauma patients".)

TRIAGE

Considerations for initial triage — Natural and man-made disasters are increasing worldwide [1]. The need to care for multiple patients may overwhelm routine practices and procedures in local health care facilities [2].

Anesthesiologists are involved in developing clear and concise plans for optimal resource management during a mass casualty event (MCE) [1]. This includes assisting with rapid triage to determine which survivors with life-threatening injuries are likely to benefit from urgent surgical and anesthetic management after events with many trauma victims (eg, mass shooting, bombing, airline crash, Targeted Automobile Ramming Mass Casualty attack [TARMAC], collapse of major structures such as a bridge or overpass due to natural causes or terrorism) [3]. Anesthesiologists also facilitate surge capacity in the operating room (OR) if an MCE results in multiple patients with traumatic injuries.

Successful management of an MCE requires the implementation of pre-existing plans to maximize the use of personnel and resources and minimize loss of life [4-7] (see 'Disaster planning and mitigation' below). The overall goal is "to do the greatest good for the greatest number." The most severely injured patients with a low chance of survival may be triaged to receive comfort care in some situations, particularly when resources are limited. (See "Overview of the management of the severely burned patient", section on 'Triage and transfer' and "Severe crush injury in adults", section on 'Triage and transport'.)

Numerous triage tools have been devised to help allocate the appropriate level of resources during a disaster and facilitate surge capacity in the OR [8,9]. Examples include Sort-Assess-Lifesaving Interventions-Triage/Treatment (SALT) system and Simple Triage and Rapid Treatment (START) [7,10-13]. Primary triage at the scene and secondary triage for transport to the hospital or at a staging area are typically done by prehospital clinicians (eg, emergency medical technicians [EMTs] and other first responders). Other clinicians, including anesthesia providers, may be asked to assist with triage after arrival at the hospital [9,14]. During the triage process, basic lifesaving interventions are performed before assigning a color-coded triage category (immediate [red], delayed [yellow], minimal [green], expectant/deceased [gray/black]) (algorithm 1) [10,13].

Use of point-of-care ultrasound — Anesthesia providers and other appropriately trained specialists (eg, emergency department physicians, critical care physicians, surgeons) can screen trauma victims using point-of-care ultrasound (POCUS). Portable ultrasound devices are often used to detect occult life-threatening injuries in trauma victims. For example, focused assessment with sonography in trauma (FAST) assessment has become the standard of care in diagnosing hemoperitoneum and pericardial tamponade, as well as traumatic injuries in other parts of the body. These assessments aid in prioritizing casualty resuscitation by identifying patients requiring urgent surgical intervention. POCUS is also used to evaluate other causes of hypotension or shock (eg, intravascular volume depletion, anaphylaxis, sepsis) and respiratory distress (eg, pulmonary edema, pneumothorax).

In some cases, POCUS is used to rapidly bridge the gap between patient load and availability of advanced imaging modalities (eg, computed tomography [CT]), with retriage of some casualties [15]. Furthermore, POCUS can be used to aid venous and arterial cannulation, as well as to identify the presence of residual gastric contents, in patients who will require urgent surgery.

Several UpToDate topics discuss these and other uses of POCUS in the emergency department, OR, and critical care units:

●(See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

●(See "Evaluation of and initial approach to the adult patient with undifferentiated hypotension and shock".)

●(See "Indications for bedside ultrasonography in the critically ill adult patient".)

●(See "Overview of perioperative diagnostic uses of ultrasound".)

●(See "Basic principles of ultrasound-guided venous access".)

However, ultrasound equipment and expertise may not be available in all hospital settings, and the number of ultrasound units may be inadequate if there are a large number of casualties.

RESOURCE MANAGEMENT

Intravascular access — Peripheral intravenous (IV) access is established in most patients for the administration of fluid, blood products, and medications; furthermore, blood drawn from the cannula may be used to perform point-of-care (POC) laboratory tests. (See 'Point-of-care testing' below.)

Intraosseous (IO) cannulation is considered when venous access is challenging, since the bone marrow cavity serves as a non-collapsible vascular entry point for the administration of drugs and resuscitation fluids. Frequently used sites for IO cannulation are the proximal humerus, tibia, and sternum. Higher flow rates can be achieved via the sternal IO versus other IO routes [16]. (See "Intraosseous infusion".)

When indicated, an intra-arterial catheter should be inserted as soon as feasible to continuously monitor arterial blood pressure (BP), evaluate respirophasic variations in the arterial waveform to predict fluid responsiveness (figure 1 and figure 2), and to facilitate frequent blood sampling. Uses of an intra-arterial catheter and insertion sites and techniques are discussed separately. (See "Intra-arterial catheterization for invasive monitoring: Indications, insertion techniques, and interpretation".)

Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be used as a temporizing solution for non-compressible traumatic hemorrhage, although less commonly in a mass casualty event (MCE) setting [17-21]. (See "Overview of damage control surgery and resuscitation in patients sustaining severe injury" and "Endovascular methods for aortic control in trauma".)

Monitoring — Conventional anesthesia monitoring systems typically include gas analyzers, respiratory monitors, and integrated capnography incorporated into anesthesia machine workstations (see "Basic patient monitoring during anesthesia"). Strategies to manage limitations of monitoring resources in some extreme situations such as treating victims of an MCE in a resource-limited hospital or managing the arrival of an overwhelming number of injured patients that generate the need for more equipment than is available in an otherwise well-equipped hospital include the following:

●Frequent rather than continuous monitoring – Adherence to American Society of Anesthesiologists (ASA) standards for basic anesthesia monitoring may prove challenging if there are personnel shortages during an MCE [22]. Temporary absences of the anesthesia clinician may occur, with interruptions of continual patient monitoring.

●Use of conventional vital signs – This may include manual determinations of BP, pulse, and respirations, plus the use of pulse oximetry. If capnography is not available, adequacy of ventilation for patients requiring anesthesia may be monitored using clinical signs, including auscultation of breath sounds, movement of the reservoir bag, and chest excursions. (See "Carbon dioxide monitoring (capnography)".)

In the unlikely situation that no monitoring equipment is available, clinicians can revert to the basics of clinical examination. Pulse and respirations counted over 15 seconds can be used to calculate heart rate (HR) and respiratory rate (RR) per minute. Palpation of diminished or absent peripheral pulses may indicate hypotension, while delayed peripheral capillary refill time indicates poor perfusion.

Fortunately, a large number of off-the-shelf pulse oximeters are available to monitor blood oxygen saturation (SpO₂) and HR [23]. Although measurements are reasonably accurate, even in poorly perfused patients [24], the true oxygen (O₂) saturation may be overestimated in dark-skinned individuals, leading to higher rates of occult hypoxemia [25,26].

Airway equipment — When resources are limited, specific strategies for airway management may include:

●Mouth-to-mask ventilation – Opening the airway is an advisable intervention for all victims. For children who are not breathing, at least two rescue breaths are recommended. Mouth-to-mask ventilation offers temporary rescue support before tracheal intubation can be accomplished. Supplemental O₂ can be delivered to raise the inspired O₂ concentration.

●Bag-mask ventilation – When properly performed, bag-mask ventilation enables clinicians to provide adequate ventilation and oxygenation to a patient requiring airway support. (See "Basic airway management in adults", section on 'Bag-mask ventilation'.)

●Airway supplies and adjuncts – Many supplies for airway management are typically available in multiple high-use clinical areas, including standard oropharyngeal and nasopharyngeal airway adjuncts, and intubation adjuncts such as stylets and bougies. These items can be accessed from the emergency department (ED), operating room (OR) suites, post-anesthesia care unit (PACU), and intensive care units (ICUs) when resources are limited. Cardiac arrest carts and airway carts are an additional source of these key supplies that can be transported to any location. Airway supplies should be replenished after use from the hospital's stock of supplies. However, restocking new supplies on these carts may be limited by the physical size of each item and the quantity kept in stock in an individual institution.

●Supraglottic airway (SGA) devices – Prior to tracheal intubation, an SGA may be used to optimize oxygenation and ventilation when mask ventilation is suboptimal [27]. Also, an SGA may be used as a bridge to tracheal intubation when immediately establishing a definitive airway is not possible with a large number of casualties. Furthermore, the latest generation SGA devices allow continuous ventilation via the SGA throughout the intubation procedure [28]. Of the SGA devices, the iGel is increasingly the most commonly used device outside the OR [29].

●Laryngoscopes – Ideally, a variety of types of equipment will be available to perform either direct or indirect laryngoscopy and tracheal intubation. The use of video laryngoscopes (VL) is becoming standard practice outside of OR settings. Disposable devices or components, and the ability to disinfect the reusable parts allow the use of a limited number of VL devices for multiple patients in different locations. Although the time required for disinfection and turnover of these items between uses may vary, according to institutionally established technician workflows and fixed disinfection protocols, these should not be modified during an MCE.

The introduction of interchangeable fiberoptic and VL devices that can be used with a single video screen has improved efficiency during the management of difficult intubations. In resource-limited environments, battery-powered VLs with an attached small screen (McGrath) are preferred. (See "Rapid sequence intubation in adults for emergency medicine and critical care".)

●Noninvasive ventilation (NIV) – NIV is a therapeutic option for some patients that requires close monitoring, but it may help bridge the gap if an MCE results in a shortage of ICU ventilators [30]. (See "Noninvasive ventilation in adults with acute respiratory failure: Practical aspects of initiation".)

Special circumstances that may be present in some MCE scenarios include:

●Need for cervical spine immobilization – Avoiding head and neck movement during tracheal intubation is critically important for victims who have suffered blunt trauma requiring cervical spine immobilization (see "Anesthesia for adults with acute spinal cord injury", section on 'Airway management'). Standard failed intubation protocols should be followed when tracheal intubation from above the vocal cords is unsuccessful, and mask ventilation and oxygenation are inadequate (algorithm 2 and algorithm 3). (See "Approach to the anatomically difficult airway in adults for emergency medicine and critical care" and "Management of the anatomically difficult airway for general anesthesia in adults".)

●Chemical or biological risk – During airway management of those involved in an MCE with chemical or biological agents, aerosolization exposure to the agent or pathogen is a risk to health care workers [31]. Appropriate personal protective equipment (PPE) will be necessary during airway management. (See "Overview of infection control during anesthetic care", section on 'PPE for aerosol-generating procedures' and "Overview of infection control during anesthetic care", section on 'Airway management'.)

Anesthesia machines

●Inadequate supply of anesthesia machines – When resources are limited, alternatives to anesthesia machines in standard OR suites include:

•Use of older anesthesia machines – In many institutions, new anesthesia equipment is installed in the main OR area, while older equipment with different components and monitors is rotated to off-site locations. This equipment can be reassigned to key areas during an MCE. (See "Considerations for non-operating room anesthesia (NORA)", section on 'Preparation of anesthetic equipment'.)

•Non-anesthesia ventilators – ICU ventilators operated by respiratory technicians may be used to provide continuous controlled mechanical ventilation. Some surgical procedures can be performed at the bedside in patients undergoing mechanical ventilation in an ICU. Small portable transport ventilators may be used to provide continuous mechanical ventilation if there is a shortage of ICU ventilators. However, these portable ventilators typically have limited functionality and are not able to deliver most modes of ventilation. (See "Modes of mechanical ventilation".)

●Need for additional filters – For MCEs involving inspired microbiological agents (eg, anthrax), a heat and moisture exchange and pathogen filter (HMEF) at the airway end of the anesthesia circuit protects the gas sampling line and the anesthesia machine from contamination and potential exposure to pathogens to subsequent patients. An additional breathing circuit filter (typically a pleated mechanical filter) can be inserted at the end of the expiratory limb to augment the effectiveness of the first filter (figure 3). (See "Overview of infection control during anesthetic care", section on 'Prevention of contamination of anesthesia machines and equipment'.)

Infusion pumps — IV infusions of anesthetic and/or vasoactive agents are often administered to critically ill patients during the perioperative period. Typically, volumetric or syringe pumps are used for their delivery. (See "Intravenous infusion devices for perioperative use".)

When resources are limited, specific strategies include using older IV infusion methods such as (see "Intravenous infusion devices for perioperative use", section on 'Manual flow regulators'):

•Incorporation of a Dial-a-Flow apparatus, which provides a mechanism to change the resistance to flow from partial to complete occlusion by compressing a longer length of IV tubing inside the device.

•Counting drops in a macrodrip (ie, 10, 15, or 20, drops per mL [gtts]) or microdrip (ie, 60 drops per mL [gtts]) infusion set. The approximate flow rate can be determined by counting the drops in the infusion set's drip chamber for 15 seconds to calculate the dose rate per minute (eg, 5 drops/15 seconds at 10 drops/mL is 120 mL/hour).

•Use of a metronome to achieve the desired rate of infusion with greater speed and accuracy [32].

Medications — Maintaining flexibility in anesthetic practice and familiarity with various anesthetic agents and alternatives is desirable since some drugs and delivery systems (eg, anesthesia machines, IV infusion devices) may not be available during an MCE [33].

When resources are limited, specific strategies include:

Intravenous medications

●Managing single-use medications – The Centers for Disease Control and Prevention (CDC) has guidelines for the administration of medications labeled as "single-dose" or "single-use" for only one patient [34]. This protects patients from infections that may occur due to contamination of medications after multiple uses. Vials of these drugs typically lack antimicrobial preservatives. However, during times of critical need, single-use vials can be repackaged by qualified health care personnel in accordance with US Pharmacopeia (USP) standards for use in multiple patients. (See "Prevention of perioperative medication errors", section on 'Pharmacy solutions'.)

●Stockpiling – Stockpiling supplies of commonly used medications is another strategy used by hospital pharmacies. However, national drug shortages and supply chain issues can deplete these reserves [35]. During an MCE, the release of items from regional or federally held stockpiles can be triggered to resupply the most impacted hospitals [35,36].

●Use after expiration date – Drug expiration dates typically range from 12 to 60 months after their production, representing the final date that the manufacturer guarantees the full potency and safety of a medication [37]. Although expired medications may lose some of their potency over time, clinical situations may arise in which expired medications are used if there are no viable alternatives.

Proper storage of medications in a cool dry dark area may aid in extending the duration of full potency. The Shelf-Life Extension Program (SLEP) monitors the long-term stability of federally stockpiled drugs [35]. Data from this program has shown that under ideal environmental storage conditions, the expiration date of many drugs could be extended by an average of 66 months.

Considerations for anesthetic agents

Techniques for inhalation anesthetic administration — When electrical power, water, and infrastructure support remain unaffected by an MCE, many patients may receive anesthesia using inhalation anesthesia techniques. In children, inhalation induction of anesthesia may be performed prior to establishing IV access. Sevoflurane is an ideal agent for this purpose, but halothane may be used if it is the only available agent in resource-limited regions [38]. (See "General anesthesia in neonates and children: Agents and techniques", section on 'Inhaled anesthetics for induction'.)

When conservation of inhalation anesthetic agents and medical gases is desired (see 'Medical gases' below), low-flow anesthesia may be employed. Reduction of fresh gas flows below 1 L/minute conserves medical gases and inhalation anesthetics while also enhancing the preservation of temperature and humidity [39]. Additional benefits include cost savings and decreased environmental pollution. Low flows may be used with sevoflurane despite previous concerns regarding the risk of compound A-associated nephropathy. Since compound A is not generated by newer carbon dioxide absorbents, flows as low as 0.5 L/minute are feasible and safe [40]. Details regarding low-flow anesthesia techniques are provided by the Anesthesia Patient Safety Foundation (https://www.apsf.org/apsf-technology-education-initiative/low-flow-anesthesia/), and in a separate topic. (See "Environmental impact of perioperative care", section on 'Managing use of anesthetic inhalation agents'.)

Use of alternative anesthetic agents and techniques — Use of other anesthetic techniques may be necessary during certain MCE scenarios:

●Total intravenous anesthesia (TIVA) – In the absence of electricity or availability of medical (ie, carrier) gases (eg, O₂, compressed air, nitrous oxide (see 'Medical gases' below)), TIVA can be used. (See "Maintenance of general anesthesia", section on 'Intravenous anesthetic agents and techniques'.)

●Local anesthesia – Many superficial cutaneous injuries and some wounds to the head or limbs may be repaired following infiltration (or topical administration) of local anesthetic drugs. Limited optional sedation can be administered, and the presence of anesthesia staff may not be necessary. (See "Clinical use of local anesthetics in anesthesia", section on 'Infiltration' and "Clinical use of local anesthetics in anesthesia", section on 'Topical anesthetics'.)

●Neuraxial or regional techniques – With appropriate monitoring by anesthesia clinicians, neuraxial or regional techniques may allow many surgical procedures to be performed when anesthesia machines are in short supply. Ultrasound-guided regional anesthetic techniques can be successfully used in treating patients with orthopedic trauma in an austere environment. (See "Overview of peripheral nerve blocks" and "Upper extremity nerve blocks: Techniques" and "Overview of neuraxial anesthesia".)

Although the popularity of intravenous regional anesthesia (IVRA) has declined, this technique is still used in some institutions, particularly in resource-limited regions [41]. Details regarding the administration of IVRA are described in a separate topic. (See "Clinical use of local anesthetics in anesthesia", section on 'Intravenous regional anesthesia'.)

●Intravenous or intramuscular ketamine – Ketamine has been used during MCEs [42]. Advantages of this agent include (see "General anesthesia: Intravenous induction agents", section on 'Advantages and beneficial effects'):

•Availability of alternative routes of administration when necessary:

-Intramuscular injection can be used when IV access is impractical or inadvertently lost during induction (eg, in a severely agitated patient). In emergency settings, some surgical techniques can be performed following the administration of intramuscular ketamine. In children, intramuscular ketamine has been associated with longer sedation and rare adverse respiratory events [43,44].

-Oral or rectal administration is also feasible for children.

-IV ketamine is optimal and can be titrated according to the patient's responses to offer superior control.

•Provision of profound analgesia as well as amnesia even in subhypnotic doses. At higher dose ranges, ketamine provides general anesthesia.

•Preservation of spontaneous breathing and airway reflexes, with bronchodilatory properties.

•Less cardiovascular depression compared with other IV anesthetic agents.

●Intraosseous administration of induction agents – Standard IV induction agents may be administered via an intraosseous cannula. However, loss of consciousness occurs slower than with an IV induction.

Medical gases — Management of anesthetic and medical gases in a disaster situation or mass casualty is challenging as these resources may be rapidly depleted (see "Inhalation anesthetic agents: Properties and delivery"). The source of portable O₂ used in hospital settings is pressurized cylinders. Pressurized O₂ supports high O₂ concentrations, enabling both mechanical ventilation and high-flow O₂ therapy.

When resources are limited, specific strategies include:

●Calculate estimated duration of use for cylinders of medical gases – Durations of use can be calculated for medical gases stored under pressure (2200 pounds per square inch [psi]) to estimate how long supplies will last. The cylinders most commonly available in clinical practice are D (425 L) and E (660 L) cylinders. For an O₂ tank, the cylinder size, cylinder pressure, and gas flow must be known to use Boyle's law in the following equation to calculate the duration of time remaining for the use of the cylinder:

Duration (minutes) = (Cylinder Pressure x Cylinder Factor) / Flow

Cylinder factors are:

•D cylinder: 0.16

•E cylinder: 0.28

•G cylinder: 2.41

•H cylinder: 3.14

The cylinder factor is used to convert the content of O₂ in a particular cylinder from cubic feet to liters. As an example, for an E cylinder with a pressure of 1800 psi and a flow rate of 5 L/minute, the duration of gas flow would be approximately 100 minutes ([1800 psi x 0.28] / [5 L/minute]).

●Use an oxygen concentrator – One solution for limited O₂ supplies is the use of O₂ concentrators (these devices concentrate oxygen from the atmosphere) [45]. The World Health Organization recommends the use of concentrators because of their low cost and ability to generate high concentrations of O₂ from the air at flow rates ranging from 0.5 to 10 L/minute [45,46]. These devices are especially useful because they can be battery-powered for short periods of time (and hence function without electricity), and can otherwise produce oxygen as long as they have electrical power.

●Use low flow rates during anesthesia – As noted above, low-flow inhalation anesthesia can be used to conserve both inhalation anesthetic agents and medical gases. (See 'Techniques for inhalation anesthetic administration' above.)

Blood supplies — For any MCE that may deplete blood supplies and transfusion equipment, strategies for control of hemorrhage and blood management are critically important:

●Hemorrhage control – Hemostatic dressings (eg, Kaolin-impregnated sponges, fibrin sealant dressings), tourniquets, and external stabilization (eg, extremity fracture, pelvic fracture) may be used for rapid control of hemorrhage. Details are described in separate topics.

•(See "Overview of topical hemostatic agents and tissue adhesives", section on 'External agents'.)

•(See "Control of external hemorrhage in trauma patients".)

•(See "Fibrin sealants".)

•(See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Control of non-compressible bleeding'.)

•(See "Pelvic trauma: Initial evaluation and management", section on 'Initial stabilization and approach'.)

Antifibrinolytic agents (tranexamic acid [TXA], epsilon-aminocaproic acid [EACA]) are used to manage patients with severe traumatic hemorrhage and to reduce bleeding for some elective surgeries. Details are discussed in separate topics:

•(See "Intraoperative use of antifibrinolytic agents".)

•(See "Initial management of moderate to severe hemorrhage in the adult trauma patient", section on 'Antifibrinolytic agents'.)

•(See "Ongoing assessment, monitoring, and resuscitation of the severely injured patient", section on 'Tranexamic acid'.)

Intraoperative use of hemostatic agents and other methods to minimize transfusion are discussed separately. (See "Overview of topical hemostatic agents and tissue adhesives" and "Fibrin sealants" and "Perioperative blood management: Strategies to minimize transfusions".)

●Blood management – Patients with massive hemorrhage should be resuscitated preferentially with blood products even if resources are limited. (See "Massive blood transfusion", section on 'Trauma' and "Ongoing assessment, monitoring, and resuscitation of the severely injured patient", section on 'Transfusion'.)

The use of low-titer O-positive whole blood (LTOWB) is an ideal resuscitation strategy in MCEs owing to numerous potential physiological advantages, greater ease of administration, reduction in the overall need for transfusions, and a growing body of evidence suggesting improved outcomes [47-54]. When whole blood is not available, attempts should be made to maintain a balanced resuscitation of plasma, red blood cells, and platelets. Platelets are often in limited supply after an MCE. Further details are discussed in separate topics. (See "Ongoing assessment, monitoring, and resuscitation of the severely injured patient", section on 'Whole blood transfusion' and "Use of blood products in the critically ill", section on 'Whole blood versus RBCs'.)

In situations with severely limited blood supplies, a "walking blood bank" has been implemented [55-57]. The blood type of soldiers is determined prior to entering a combat zone so that blood can be individually donated during events requiring massive transfusion [58,59]. Blood is rapidly screened prior to transfusion and afterward to identify any transmissible disease. Both the US Army and US Marine Corps/Navy ("Valkyrie") have programs that use prescreened donors as a "walking blood bank" [58,59]. This is more difficult to implement in the civilian community. When blood products are limited, collaboration with the surgeon is critical to triage products to those most likely to survive.

Alternatives to red blood cells such as oxygen carriers may become available in the future. (See "Oxygen carriers as alternatives to red blood cell transfusion".)

Point-of-care testing — When available, POC laboratory tests such as arterial blood gases with pH, hemoglobin, electrolytes, glucose, lactate, and viscoelastic tests of hemostasis (eg, thromboelastography, thromboelastometry) are often used instead of standard laboratory tests. POC tests facilitate prompt necessary interventions while avoiding unnecessary treatments. Details are available in separate topics:

●(See "Anesthesia for adult trauma patients", section on 'Point-of-care and standard laboratory testing'.)

●(See "Intraoperative transfusion and administration of clotting factors", section on 'Intraoperative diagnostic testing'.)

●(See "Point-of-care hemostasis testing (viscoelastic tests)".)

DISASTER PLANNING AND MITIGATION

●General considerations – Management of severely injured patients according to the principles and standards of trauma care is well established. Mass casualty events (MCEs) are exceptional situations where the aim is to maximize the total number of survivors, even if this means limiting care for those with severe injuries and judged to have little chance of survival. When resources and equipment for standard care become limited, organizational coordination is required to mobilize operating room (OR) personnel and materials [60]. Normal trauma protocols may be replaced with a minimum acceptable care strategy that includes rapid assessment and treatment limited to lifesaving procedures and using minimal resources [61].

●Preparation for MCEs – Preparation involves anticipating a variety of realistic scenarios the hospital could encounter and having emergency plans for such MCEs [62]. An "all-cause" approach should be adopted when developing hospital disaster planning that includes various mechanisms of injury such as burns, radiation, chemical, and penetrating or blunt trauma.

Preparations for multiple simultaneous surgical procedures should include representatives from the entire perioperative team [1,62-64]. An example is intentional vehicular attack when a speeding motor vehicle is driven into a crowd of pedestrians [65]. The 2016 Bastille Day parade attack in Nice, France caused high rates of traumatic brain injury, emphasizing the need to prevent secondary injury in patients having non-neurosurgical procedures.

Training exercises for MCEs aim to maintain readiness for the numerous challenges [66]. A combination of discussion-based and operation-based multidisciplinary exercises targets both individuals providing care and those of the overall system delivering casualty treatment and flow. Simulations highlight shortcomings that lead to change, facilitate continual improvement of hospital response plans, and build staff confidence and feelings of preparedness [63].

The resiliency of the staff is also important to decrease psychological damage that can occur in the aftermath of an MCE during the recovery phase. Finally, discussion of mitigation of the impact on the provision of services to the community (eg, elective surgical procedures, treatment of critical illnesses unrelated to the MCE) after degradation of hospital resources during a surge of surgical cases and intensive care unit (ICU) admissions can be included in institutional planning processes [63].

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: General issues of trauma management in adults" and "Society guideline links: Care of the patient with burn injury" and "Society guideline links: Chemical terrorism".)

SUMMARY AND RECOMMENDATIONS

●Initial triage – Numerous triage tools have been devised to help allocate the appropriate level of resources during a disaster and facilitate surge capacity in the operating room (OR). Examples include Sort-Assess-Lifesaving Interventions-Triage/Treatment (SALT) and Simple Triage and Rapid Treatment (START). (See 'Considerations for initial triage' above.)

●Use of point-of-care ultrasound (POCUS) – POCUS assessment can be used to diagnose hemoperitoneum, pericardial tamponade, and traumatic injuries in other parts of the body to facilitate triage of patients requiring urgent surgical intervention or advanced imaging. Other causes of hypotension or shock (eg, intravascular volume depletion, anaphylaxis, sepsis) and respiratory distress (eg, pulmonary edema, pneumothorax) are also recognized. Several UpToDate topics discuss these uses of POCUS:

•(See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

•(See "Evaluation of and initial approach to the adult patient with undifferentiated hypotension and shock".)

•(See "Indications for bedside ultrasonography in the critically ill adult patient".)

•(See "Overview of perioperative diagnostic uses of ultrasound".)

•(See "Basic principles of ultrasound-guided venous access".)

●Resource management – Perioperative considerations in settings with multiple victims and limited resources include (see 'Resource management' above):

•Intravascular access – Alternative techniques to establish intravenous (IV) or intraosseous (IO) access may be necessary. (See 'Intravascular access' above.)

•Monitors – Monitoring may be limited to conventional vital signs (ie, manual determinations of blood pressure [BP], pulse, respirations) plus pulse oximetry. Off-the-shelf pulse oximeters are typically available to monitor blood oxygen saturation (SpO₂) and heart rate (HR). (See 'Monitoring' above.)

•Airway equipment – Depending on the patient's condition and available resources, initial airway management may include (see 'Airway equipment' above):

-Bag-mask ventilation

-Laryngoscopes

-Supraglottic airway (SGA) devices

-Airway adjuncts such as oropharyngeal and nasopharyngeal airway adjuncts, and intubation adjuncts (stylets and bougies)

In addition to OR suites, these items are often found in the emergency department (ED), post-anesthesia care unit (PACU), intensive care units (ICUs), and on cardiac arrest and airway carts.

•Anesthesia machines – Alternatives to anesthesia machines in standard OR suites include the use of older anesthesia machines and equipment with less familiar components and monitors located in off-site anesthetizing locations. Some surgical procedures can be performed at the bedside in ICU patients on controlled mechanical ventilation. Small portable transport ventilators may be employed if there is a shortage of ICU ventilators, but may be unable to deliver most modes of ventilation. (See 'Anesthesia machines' above.)

For mass casualty events (MCEs) involving chemical or biological agents, a heat and moisture exchange filter (HMEF) is placed at the airway end of the anesthesia circuit to protect the gas sampling line and the anesthesia machine from contamination, and an additional breathing circuit filter is inserted at the end of the expiratory limb (figure 3).

•Infusion pumps – If the availability of IV infusion devices is limited, older methods may be used such as incorporation of a Dial-a-Flow apparatus or counting drops in a macrodrip (ie, 10, 15, or 20 drops per mL [gtts]) or microdrip (ie, 60 drops per mL [gtts]) infusion set. These methods are discussed in a separate topic. (See "Intravenous infusion devices for perioperative use", section on 'Manual flow regulators'.)

•Medications

-General considerations – Maintaining familiarity with various anesthetic agents and alternatives is desirable since some drugs and delivery systems (eg, anesthesia machines, IV infusion devices) may not be available during an MCE. (See 'Intravenous medications' above.)

-Inhalation agents – When conservation of inhalation anesthetic agents and medical gases is desired, low-flow anesthesia with fresh gas flows <1 L/minute conserves medical gases and inhalation anesthetics and also preserves temperature and humidity. (See 'Techniques for inhalation anesthetic administration' above and 'Medical gases' above.)

-Alternative techniques – Alternative anesthetic techniques include the use of local, regional, or neuraxial anesthesia, administration of intramuscular, oral, or rectal ketamine to provide anesthesia or the use of an IO route medication administration. (See 'Use of alternative anesthetic agents and techniques' above.)

•Blood supplies – Strategies for hemorrhage control and blood management are important when blood supplies are limited, as discussed above and in more detail in the linked topics. (See 'Blood supplies' above.)

•Point-of-care testing – Point-of-care (POC) laboratory tests (eg, arterial blood gases with pH, hemoglobin, electrolytes, glucose, lactate, and viscoelastic tests of hemostasis) facilitate prompt necessary interventions, while avoiding unnecessary treatments, as discussed above and in more detail in the linked topic. (See 'Point-of-care testing' above.)

●Disaster planning – Hospital disaster planning and preparing for multiple simultaneous surgical procedures should include representatives from the entire perioperative team. (See 'Disaster planning and mitigation' above.)