Nursing Chapter 18 Intraoperation Notes

Chapter 18 Intraoperative Nursing I. The Surgical Team A. Circulating Nurse ● The circulating nurse (or circulator), a qualified registered nurse, works in collaboration with surgeons, anesthesia providers, and other health care providers to plan the best course of action for each patient. ● In this leadership role, the circulating nurse manages the OR and protects the patient’s safety and health by monitoring the activities of the surgical team, checking the OR conditions, and continually assessing the patient for signs of injury and implementing appropriate interventions. ● A foremost responsibility includes verifying consent; if not obtained, surgery may not commence. ● The team is coordinated by the circulating nurse, who ensures cleanliness, proper temperature, humidity, appropriate lighting, safe function of equipment, and the availability of supplies and materials. ● The circulating nurse monitors aseptic practices to avoid breaks in technique while coordinating the movement of related personnel (medical, x-ray, and laboratory), as well as implementing fire safety precautions (Seifert, Peterson, & Graham, 2015). ● The circulating nurse also monitors the patient and documents specific activities throughout the operation to ensure the patient’s safety and well-being. ● In addition, the circulating nurse is responsible for ensuring that the second verification of the surgical procedure and site takes place and is documented (see Fig. 18-1). - In some institutions, this is referred to as a time out, surgical pause, or universal protocol that takes place among the surgical team prior to induction of anesthesia with a briefing about anticipated problems, potential complications, allergies, and comorbidities. - Every member of the surgical team verifies the patient’s name, procedure, and surgical site using objective documentation and data before beginning the surgery. - Identifying patients correctly is a 2016 National Patient Safety Goal (see Chart 17-8 in Chapter 17). Research suggests that the use of surgical checklists (see Fig. 18-1) help create a culture of safety and reduce morbidity and mortality (Huang, Kim & Berry, 2013). - A team debriefing session, led by the circulating nurse, often follows the completion of surgery to identify potential problems with the postsurgical care of the patient and potential areas for improvement. B. The Scrub Nurse ● The registered nurse, licensed practical nurse, or surgical technologist (or assistant) performs the activities of the scrub role, including performing hand hygiene; setting up the sterile equipment, tables and sterile field; preparing sutures, ligatures, and special equipment (e.g., a laparoscope, which is a thin endoscope inserted through a small incision into a cavity or joint using fiber-optic technology to project live images of structures onto a video monitor); and assisting the surgeon and the surgical assistants during the procedure by anticipating the instruments and supplies that will be required, such as sponges, drains, and other equipment. ● As the surgical incision is closed, the scrub person and the circulating nurse count all needles, sponges, and instruments to be sure that they are accounted for and not retained as a foreign body in the patient (Association of PeriOperative Registered Nurses [AORN], 2014; Rothrock, 2014). Standards call for all sponges used in surgery to be visible on x-ray and for sponge counts to take place at the beginning of surgery and twice at the end (when wound closure begins and again as the skin is being closed). ● Tissue specimens obtained during surgery are labeled by the person in the scrub role and sent to the laboratory by the circulating nurse. C. The Surgeon The surgeon performs the surgical procedure, heads the surgical team, and is a licensed physician (MD or DO), oral surgeon (DDS or DMD), or podiatrist (DPM) who is specially trained and qualified. Qualifications and training must adhere to Joint Commission standards, hospital standards, and local and state admitting practices and procedures D. The Registered First Nurse Assistant ● The registered nurse first assistant (RNFA) is another member of the OR team. Although the scope of practice of the RNFA depends on each state’s nurse practice act, the RNFA practices under the direct supervision of the surgeon. ● RNFA responsibilities may include handling tissue, providing exposure at the operative field, suturing, and maintaining hemostasis (Rothrock, 2014). ● The role requires a thorough understanding of anatomy and physiology, tissue handling, and the principles of surgical asepsis. ● The RNFA must be aware of the objectives of the surgery, must have the knowledge and ability to anticipate needs and to work as a skilled member of a team, and must be able to handle any emergency situation in the OR. E. The Anesthesiologist and CRNA ● An anesthesiologist is a physician specifically trained in the art and science of anesthesiology. ● A CRNA is a qualified and specifically trained health care professional who administers anesthetic agents, has graduated from an accredited nurse anesthesia master’s program, and has passed examinations sponsored by the American Association of Nurse Anesthetists. ● The anesthesiologist or CRNA assesses the patient before surgery, selects the anesthesia, administers it, intubates the patient if necessary, manages any technical problems related to the administration of the anesthetic agent, and supervises the patient’s condition throughout the surgical procedure. ● Before the patient enters the OR, often at preadmission testing, the anesthesiologist or CRNA visits the patient to perform an assessment, supply information, and answer questions. ● The type of anesthetic agent to be given, previous reactions to anesthetic medications, and known anatomic abnormalities that would make airway management difficult are among topics addressed. ● The anesthesiologist or CRNA uses the American Society of Anesthesiologists (ASA) Physical Status Classification System to determine the patient’s status. A patient who is classified as P2, P3, or P4 has a systemic disease that may or may not be related to the cause of surgery. If a patient with a classification of P1, P2, P3, P4, or P5 requires emergency surgery, an E is added to the physical status designation (e.g., P1E, P2E). P6 refers to a patient who is brain dead and is undergoing surgery as an organ donor. The abbreviations ASA1 through ASA6 are often used interchangeably with P1 to P6 to designate physical status (Rothrock, 2014). ● When the patient arrives in the OR, the anesthesiologist or CRNA reassesses the patient’s physical condition immediately prior to initiating anesthesia. The anesthetic agent is given, and the patient’s airway is maintained through an intranasal intubation (if the surgeon is using an oral approach to surgery), intubation with an endotracheal tube (ETT), or a laryngeal mask airway (LMA). During surgery, the anesthesiologist or CRNA monitors the patient’s blood pressure, pulse, and respirations, as well as the electrocardiogram (ECG), blood oxygen saturation level, tidal volume, blood gas levels, blood pH, alveolar gas concentrations, and body temperature. Monitoring by electroencephalography (EEG) is sometimes required. Levels of anesthetic medications in the body can also be determined; a mass spectrometer can provide instant readouts of critical concentration levels on display terminals. This information is used to assess the patient’s ability to breathe unassisted or the need for mechanical assistance if ventilation is poor and the patient is not breathing well independently. II. The Surgical Environment ● The surgical environment is known for its stark appearance and cool temperature. The surgical suite is behind double doors, and access is limited to authorized, appropriately clad personnel. Precautions include adherence to principles of surgical asepsis; strict control of the OR environment is required, including use of laminar airflow rooms as indicated for the surgical procedure, and decreasing noise as well as the number of operating theater door openings (Pada & Perl, 2015). Policies governing this environment address such issues as the health of the staff; the cleanliness of the rooms; the sterility of equipment and surfaces; processes for scrubbing, gowning, and gloving; and OR attire (AORN, 2014). ● Warming the patient, which may begin in the preoperative phase of surgery, is continued or initiated during the perioperative stage (Erdling & Johansson, 2015). Maintaining normothermia has been linked to improved patient outcomes, such as enhanced healing, lower infection rates, decreased pain intensity, and reduced malaise (Sobczak, 2014) (see Chart 18-2). ● To provide the best possible conditions for surgery, the OR is situated in a location that is central to all supporting services (e.g., pathology, x-ray, and laboratory). The OR has special air filtration devices to screen out contaminating particles, dust, and pollutants. ● Many National Patient Safety Goals pertain to the perioperative areas (see Chart 17-8 in Chapter 17); however, the one with the most direct relevance to the OR is to identify patient safety risks. A unique risk is the risk of fire in the OR due to three factors: a source of fuel, an oxygen source, and a mechanism to ignite a fire (AORN, 2014; ASPAN, 2015). All surgical services personnel must familiarize themselves with the department fire emergency response plan and be competent in the use and safeguards of all combustible materials and equipment in the surgical environment (Guglielmi, 2014; Seifert et al., 2015). Surgical drapes provide an opportunity for oxygen to concentrate; a stray spark could more easily ignite a fire. This occurs most commonly in ambulatory surgery settings (Joint Commission, 2016). To further improve safety, electrical hazards, emergency exit clearances, and storage of equipment and anesthetic gases are monitored periodically by official agencies, such as the respective state Department of Health and the Joint Commission. ● To help decrease microbes, the surgical area is divided into three zones: the unrestricted zone, where street clothes are allowed; the semirestricted zone, where attire consists of scrub clothes and caps; and the restricted zone, where scrub clothes, shoe covers, caps, and masks are worn. The surgeons and other surgical team members wear additional sterile clothing and protective devices during surgery. ● The AORN recommends specific practices for personnel wearing surgical attire to promote a high level of cleanliness in a particular practice setting (AORN, 2014). OR attire includes close-fitting cotton dresses, pantsuits, jumpsuits, gowns, and jackets. Knitted cuffs on sleeves prevent organisms from shedding and being released into the immediate surroundings. Shirts and waist drawstrings should be tucked inside the pants to prevent accidental contact with sterile areas and to contain skin shedding. Wet or soiled garments should be changed. ● Masks are worn at all times in the restricted zone of the OR. High-filtration masks decrease the risk of postoperative wound infection by containing and filtering microorganisms from the oropharynx and nasopharynx. Masks should fit tightly; should cover the nose and mouth completely; and should not interfere with breathing, speech, or vision. Masks must be adjusted to prevent venting from the sides. Disposable masks have a filtration efficiency exceeding 95%. Masks are changed between patients and should not be worn outside the surgical department. The mask must be either on or off; it must not be allowed to hang around the neck. ● Headgear should completely cover the hair (head and neckline, including beard) so that hair, bobby pins, clips, and particles of dandruff or dust do not fall on the sterile field. ● Shoes designated for use inside the OR (not worn home) should be comfortable and supportive. Shoe covers are used when spills or splashes are anticipated. If worn, the covers should be changed whenever they become wet, torn, or soiled (AORN 2014; Rothrock, 2014). ● Barriers such as scrub attire and masks do not entirely protect the patient from microorganisms. Upper respiratory tract infections, sore throats, and skin infections in staff and patients are sources of pathogens and must be reported. ● Because artificial fingernails harbor microorganisms and can cause nosocomial infections, a ban on artificial nails by OR personnel is supported by the Centers for Disease Control and Prevention (CDC), AORN, and the Association for Professionals in Infection Control and Epidemiology (APIC). Research provides support for policies prohibiting artificial nails for health care workers (AORN, 2014). Short, natural fingernails are encouraged. A. Principles of Surgical Asepsis ● Surgical asepsis prevents the contamination of surgical wounds. The patient’s natural skin flora or a previously existing infection may cause postoperative wound infection. Rigorous adherence to the principles of surgical asepsis by OR personnel is basic to preventing surgical site infections. ● All surgical supplies, instruments, needles, sutures, dressings, gloves, covers, and solutions that may come in contact with the surgical wound or exposed tissues must be sterilized before use (Rothrock, 2014). Traditionally, the surgeon, surgical assistants, and nurses prepared themselves by scrubbing their hands and arms with antiseptic soap and water; however, this practice is being challenged by research investigating the optimal length of time to scrub and the best preparation to use. In some institutions, various alcohol-based products or scrub less soaps are used to prepare the patient for surgery (Rothrock, 2014) but are only effective when no gross contaminants are present. ● Surgical team members wear long-sleeved, sterile gowns and gloves. Head and hair are covered with a cap, and a mask is worn over the nose and mouth to minimize the possibility that bacteria from the upper respiratory tract will enter the wound. During surgery, only personnel who have scrubbed, gloved, and gowned touch sterilized objects. Nonscrubbed personnel refrain from touching or contaminating anything sterile. ● An area of the patient’s skin larger than that requiring exposure during the surgery is meticulously cleansed, and an antiseptic solution is applied (Rothrock, 2014). If hair removal needs to take place and this was unable to be performed before the patient arrived in the OR suite, this is done immediately before the procedure with electric clippers (not shaved) to minimize the risk of infection (AORN, 2014). The remainder of the patient’s body is covered with sterile drapes. i. Environmental Controls ❖ In addition to the protocols described previously, surgical asepsis requires meticulous cleaning and maintenance of the OR environment. Floors and horizontal surfaces are cleaned between cases with detergent, soap, and water or a detergent-germicide. Sterilized equipment is inspected regularly to ensure optimal operation and performance. ❖ All equipment that comes into direct contact with the patient must be sterile. Sterilized linens, drapes, and solutions are used. Instruments are cleaned and sterilized in a unit near the OR. Individually wrapped sterile items are used when additional individual items are needed. ❖ Airborne bacteria are a concern. To decrease the amount of bacteria in the air, standard OR ventilation provides 15 air exchanges per hour, at least 3 of which are fresh air (AORN, 2014; Rothrock, 2014). A room temperature of 20°C to 24°C (68°F to 73°F), humidity between 30% and 60%, and positive pressure relative to adjacent areas are maintained. Staff members shed skin scales, resulting in about 1000 bacteria-carrying particles (or colony-forming units [CFUs]) per cubic foot per minute. With the standard air exchanges, air counts of bacteria are reduced to 50 to 150 CFUs per cubic foot per minute. Systems with high-efficiency particulate air (HEPA) filters are needed to remove particles larger than 0.3 μm (Rothrock, 2014). Unnecessary personnel and physical movement may be restricted to minimize bacteria in the air and achieve an OR infection rate no greater than 3% to 5% in clean, infection-prone surgery. ❖ Some ORs have laminar airflow units. These units provide 400 to 500 air exchanges per hour (Rothrock, 2014). When used appropriately, laminar airflow units result in fewer than 10 CFUs per cubic foot per minute during surgery. The goal for a laminar airflow–equipped OR is an infection rate of less than 1%. An OR equipped with a laminar airflow unit is frequently used for total joint replacement or organ transplant surgery. ❖ Even using all precautions, wound contamination may inadvertently occur. Constant surveillance and conscientious technique in carrying out aseptic practices are necessary to reduce the risk of contamination and infection. ii. Basic Guidelines for Maintaining Surgical Asepsis All practitioners involved in the intraoperative phase have a responsibility to provide and maintain a safe environment. Adherence to aseptic practice is part of this responsibility. The basic principles of aseptic technique follow (AORN, 2014): ❖ All materials in contact with the surgical wound or used within the sterile field must be sterile. Sterile surfaces or articles may touch other sterile surfaces or articles and remain sterile; contact with unsterile objects at any point renders a sterile area contaminated. ❖ Gowns of the surgical team are considered sterile in front from the chest to the level of the sterile field. The sleeves are also considered sterile from 2 in above the elbow to the stockinette cuff. ❖ Sterile drapes are used to create a sterile field (see Fig. 18-2). Only the top surface of a draped table is considered sterile. During draping of a table or patient, the sterile drape is held well above the surface to be covered and is positioned from front to back. ❖ Items are dispensed to a sterile field by methods that preserve the sterility of the items and the integrity of the sterile field. After a sterile package is opened, the edges are considered unsterile. Sterile supplies, including solutions, are delivered to a sterile field or handed to a scrubbed person in such a way that the sterility of the object or fluid remains intact. ❖ The movements of the surgical team are from sterile to sterile areas and from unsterile to unsterile areas. Scrubbed people and sterile items contact only sterile areas; circulating nurses and unsterile items contact only unsterile areas. ❖ Movement around a sterile field must not cause contamination of the field. Sterile areas must be kept in view during movement around the area. At least a 1-ft distance from the sterile field must be maintained to prevent inadvertent contamination. ❖ Whenever a sterile barrier is breached, the area must be considered contaminated. A tear or puncture of the drape permitting access to an unsterile surface underneath renders the area unsterile. Such a drape must be replaced. ❖ Every sterile field is constantly monitored and maintained. Items of doubtful sterility are considered unsterile. Sterile fields are prepared as close as possible to the time of use. ❖ The routine administration of hyperoxia (high levels of oxygen) is not recommended to reduce surgical site infections. iii. Health Hazards Associated With the Surgical Environment ● Faulty equipment, improper use of equipment, exposure to toxic substances, surgical plume (smoke generated by electrosurgical cautery), as well as infectious waste, cuts, needle stick injuries, and lasers are some of the associated hazards in the surgical environment (Rothrock, 2014). Internal monitoring of the OR includes the analysis of surface swipe samples and air samples for infectious and toxic agents. In addition, policies and procedures for minimizing exposure to body fluids and reducing the dangers associated with lasers and radiation are identified in AORN standards (AORN, 2014). ● Regardless of the size or location of an incision, unintentional retention of an object (e.g., sponge, instrument) can occur. A retained object can cause wound infection or disruption, an abscess can form, and fistulas may develop between organs (Rothrock, 2014). Laser Risks The AORN has recommended practices for laser safety (AORN, 2014). When lasers are in use, warning signs must be clearly posted to alert personnel. Safety precautions are implemented to reduce the possibility of exposing the eyes and skin to laser beams, to prevent inhalation of the laser plume (smoke and particulate matter), and to protect the patient and personnel from the risk of surgical fire and electrical hazards (Guglielmi, 2014; Norton, Gorgone, & Belanger, 2014). Several types of lasers are available for clinical use; perioperative personnel should be familiar with the unique features, specific operation, and safety measures for each type of laser used in the practice setting and wear appropriate laser goggles for the type of laser beam in use. Registered nurses trained and certified in laser safety maintain the established standards in the OR (AORN, 2014). Smoke evacuators are used in some procedures to remove the laser plume from the operative field. In recent years, this technology has been extended to all surgical cases to protect the surgical team from the potential hazards associated with the generalized smoke plume generated by standard electric cautery units. Exposure to Blood and Body Fluids OR attire has changed dramatically since the advent of acquired immune deficiency syndrome (AIDS). Double-gloving is routine in trauma and other types of surgery where sharp bone fragments are present. In addition to the routine scrub suit and double gloves, some surgical personnel wear rubber boots, a waterproof apron, and sleeve protectors. Goggles, or a wraparound face shield, are worn to protect against splashing when the surgical wound is irrigated or when bone drilling is performed. In hospitals where numerous total joint procedures are performed, a complete bubble mask may be used. This mask provides full-barrier protection from bone fragments and splashes. Ventilation is accomplished through an accompanying hood with a separate air filtration system. III. The Surgical Experience Types of Anesthesia and Sedation Research estimates anesthesia-related death rates in the United States to be less than 1 per 10,000 surgeries (Barash et al., 2013). For the patient, the anesthesia experience consists of having an IV line inserted, if it was not inserted earlier; receiving a sedating agent prior to induction with an anesthetic agent; losing consciousness; being intubated, if indicated; and then receiving a combination of anesthetic agents. Typically, the experience is a smooth one, and the patient has no recall of the events. The main types of anesthesia are general anesthesia (inhalation, IV), regional anesthesia (epidural, spinal, and local conduction blocks), moderate sedation (monitored anesthesia care [MAC]), and local anesthesia. A. General Anesthesia ❖ Anesthesia is a state of narcosis (severe central nervous system depression produced by pharmacologic agents), analgesia, relaxation, and reflex loss. Patients under general anesthesia are not arousable, not even to painful stimuli. They lose the ability to maintain ventilatory function and require assistance in maintaining a patent airway. Cardiovascular function may be impaired as well. ❖ The Joint Commission has issued an alert regarding the phenomenon of patients being partially awake while under general anesthesia (referred to as anesthesia awareness). Patients at greatest risk of anesthesia awareness are cardiac, obstetric, and major trauma patients. The entire surgical team must be aware of this phenomenon and help prevent or manage it (Joint Commission, 2011). ❖ General anesthesia consists of four stages, each associated with specific clinical manifestations (Rothrock, 2014). Understanding of these stages is necessary for nurses because of the emotional support that the patient might need as anesthesia progresses. These stages occur in reverse as the patient wakes up at the end of surgery, so the nurse must be aware of the need for appropriate patient support. ● Stage I: beginning anesthesia. ➔ Dizziness and a feeling of detachment may be experienced during induction. ➔ The patient may have a ringing, roaring, or buzzing in the ears and, although still conscious, may sense an inability to move the extremities easily. ➔ These sensations can result in agitation. ➔ During this stage, noises are exaggerated; even low voices or minor sounds seem loud and unreal. ➔ For these reasons, unnecessary noises and motions are avoided when anesthesia begins. ● Stage II: excitement. ➔ The excitement stage, characterized variously by struggling, shouting, talking, singing, laughing, or crying, is often avoided if IV anesthetic agents are given smoothly and quickly. ➔ The pupils dilate, but they constrict if exposed to light; the pulse rate is rapid, and respirations may be irregular. ➔ Because of the possibility of uncontrolled movements of the patient during this stage, the anesthesiologist or CRNA must always be assisted by someone ready to help restrain the patient or to apply cricoid pressure in the case of vomiting to prevent aspiration. ➔ Manipulation increases circulation to the operative site and thereby increases the potential for bleeding. ● Stage III: surgical anesthesia. ➔ Surgical anesthesia is reached by administration of anesthetic vapor or gas and supported by IV agents as necessary. ➔ The patient is unconscious and lies quietly on the table. The pupils are small but constrict when exposed to light. ➔ Respirations are regular, the pulse rate and volume are normal, and the skin is pink or slightly flushed. ➔ With proper administration of the anesthetic agent, this stage may be maintained for hours in one of several planes, ranging from light (1) to deep (4), depending on the depth of anesthesia needed. ● Stage IV: medullary depression. This stage is reached if too much anesthesia has been given. ➔ Respirations become shallow, the pulse is weak and thready, and the pupils become widely dilated and no longer constrict when exposed to light. ➔ Cyanosis develops and, without prompt intervention, death rapidly follows. ➔ If this stage develops, the anesthetic agent is discontinued immediately and respiratory and circulatory support is initiated to prevent death. ➔ Stimulants, although rarely used, may be given; narcotic antagonists can be used if the overdose is due to opioids. It is not a planned stage of surgical anesthesia. ● When opioid agents (narcotics) and neuromuscular blockers (relaxants) are given, several of the stages are absent. During smooth administration of an anesthetic agent, there is no sharp division between stages. The patient passes gradually from one stage to another, and it is through close observation of the signs exhibited by the patient that an anesthesiologist or CRNA controls the situation. The responses of the pupils, the blood pressure, and the respiratory and cardiac rates are among the most reliable guides to the patient’s condition. ● Anesthetic medications produce anesthesia because they are delivered to the brain at a high partial pressure that enables them to cross the blood–brain barrier. Relatively large amounts of anesthetic medication must be given during induction and the early maintenance phases because the anesthetic agent is recirculated and deposited in body tissues. As these sites become saturated, smaller amounts of the anesthetic agent are required to maintain anesthesia because equilibrium or near-equilibrium has been achieved between brain, blood, and other tissues. When possible, the anesthesia induction (initiation) begins with IV anesthesia and is then maintained at the desired stage by inhalation methods, achieving a smooth transition and eliminating the obvious stages of anesthesia (see Table 18-1). All are given in combination with oxygen and usually nitrous oxide as well. ● Any condition that diminishes peripheral blood flow, such as vasoconstriction or shock, may reduce the amount of anesthetic medication required. Conversely, when peripheral blood flow is unusually high, as in a muscularly active or apprehensive patient, induction is slower, and greater quantities of anesthetic agents are required because the brain receives a smaller quantity of anesthetic agent. B. Inhalation ● Inhaled anesthetic agents include volatile liquid agents and gases. Volatile liquid anesthetic agents produce anesthesia when their vapors are inhaled. Some commonly used inhalation agents are included in Table 18-1. All are given in combination with oxygen and usually nitrous oxide as well. ● Gas anesthetic agents are given by inhalation and are always combined with oxygen. Nitrous oxide is the most commonly used gas anesthetic agent. When inhaled, the anesthetic agents enter the blood through the pulmonary capillaries and act on cerebral centers to produce loss of consciousness and sensation. When anesthetic administration is discontinued, the vapor or gas is eliminated through the lungs. ● The vapor from inhalation anesthetic agents can be given to the patient by several methods. The inhalation anesthetic agent may be given through an LMA—a flexible tube with an inflatable silicone ring and cuff that can be inserted into the larynx (see Fig. 18-3A). The endotracheal technique for administering anesthetic medications consists of introducing a soft rubber or plastic ETT into the trachea, usually by means of a laryngoscope. The ETT may be inserted through either the nose (see Fig. 18-3B) or mouth (see Fig. 18-3C). When in place, the tube seals off the lungs from the esophagus so that if the patient vomits, stomach contents do not enter the lungs. C. Intravenous Administration ● General anesthesia can also be produced by the IV administration of various anesthetic and analgesic agents, such as barbiturates, benzodiazepines, nonbarbiturate hypnotics, dissociative agents, and opioid agents. Table 18-2 lists commonly used IV anesthetic and analgesic agents, including IV medications used as muscle relaxants in the intraoperative period. These medications may be given to induce or maintain anesthesia. Although they are often used in combination with inhalation anesthetic agents, they may be used alone. They may also be used to produce moderate sedation, as discussed later in this chapter. ● An advantage of IV anesthesia is that the onset of anesthesia is pleasant; there is none of the buzzing, roaring, or dizziness known to follow administration of an inhalation anesthetic agent. The duration of action is brief, and the patient awakens with little nausea or vomiting. ● The IV anesthetic agents are nonexplosive, require little equipment, and are easy to administer. The low incidence of postoperative nausea and vomiting makes the method useful in eye surgery, because in this setting vomiting would increase intraocular pressure and endanger vision in the operated eye. IV anesthesia is useful for short procedures but is used less often for the longer procedures of abdominal surgery. It is not indicated for those who require intubation because of their susceptibility to respiratory obstruction. The combination of IV and inhaled anesthetic agents produces an effective and smooth experience for the patient, with a controlled emergence following surgery. ● IV neuromuscular blockers (muscle relaxants) block the transmission of nerve impulses at the neuromuscular junction of skeletal muscles. Muscle relaxants are used to relax muscles in abdominal and thoracic surgery, relax eye muscles in certain types of eye surgery, facilitate endotracheal intubation, treat laryngospasm, and assist in mechanical ventilation.