Anaesthesia in haemodynamically compromised emergency patients: does ketamine represent the best choice of induction agent?

Veterinary and human anaesthesia: an overview of some parallels and contrasts

The history of human and veterinary anaesthesia is both intertwined and parallel. Physicians and anaesthetists often first experimented on animals and developments from human anaesthesia have been incorporated into veterinary medicine. Within veterinary medicine, anaesthesia is a specialty discipline as it is in human medicine. Veterinary anaesthetists undertake additional training and rigorous examinations for a diploma or fellowship. In contrast to human anaesthesia in Australia and New Zealand, veterinary anaesthesia is often performed by non-specialists and by veterinary nurses. Veterinary anaesthesia uses many of the same drugs for premedication, induction and maintenance of anaesthesia as human anaesthesia. However, there are species specific effects of some of the drugs used that differ from the effects in humans. Furthermore, some agents, particularly alpha-2 adrenoreceptor agonists and ketamine, are used very widely in veterinary practice. Also in contrast to most human anaesthesia, in large animal and exotic animal practice the patients can present a physical danger to the anaesthetist. The most notable contrast between human and veterinary anaesthesia is in the reported perioperative complication and mortality rates, with a species dependent perianaesthetic mortality of up to 2% in dogs, cats and horses and greater than 2% in guinea pigs and birds, which is up to 100-fold higher than in human anaesthesia.

Ketamine: use in anesthesia

The role of ketamine anesthesia in the prehospital, emergency department and operating theater settings is not well defined. A nonsystematic review of ketamine was performed by authors from Australia, Europe, and North America. Results were discussed among authors and the final manuscript accepted. Ketamine is a useful agent for induction of anesthesia, procedural sedation, and analgesia. Its properties are appealing in many awkward clinical scenarios. Practitioners need to be cognizant of its side effects and limitations.

Perioperative treatment of patients with sepsis

PURPOSE OF REVIEW

Key elements in the initial resuscitation and stabilization of the patient with sepsis are fluid therapy, vasopressor or inotropic support, administration of adequate antibiotics and source control. This review will primarily discuss fluid, vasopressor and antibiotic therapy because these have been the subject of the recent large clinical trials.

RECENT FINDINGS

On the basis of the recent large randomized clinical trials, starch solutions should be avoided in patients with sepsis because there is no evidence of benefit and clear signals of harm including adverse effects on kidney and haemostatic function and increased mortality in one trial. Ongoing trials are investigating the efficacy and safety of albumin and red blood cell transfusion in patients with sepsis. Norepinephrine should be the first-line vasopressor agent because accumulating evidence shows more adverse events with the use of dopamine. Early initiation of adequate antibiotic therapy is recommended and etomidate should not be used in patients with sepsis.

SUMMARY

Recent high-quality trials in the intensive care setting have provided data to improve the treatment and thereby the outcome of patients with sepsis. These findings may be used in the perioperative setting to minimize the harmful effects of specific interventions.

Hemorrhagic shock: The "physiology approach"

A shift of approach from ‘clinics trying to fit physiology’ to the one of ‘physiology to clinics’, with interpretation of the clinical phenomena from their physiological bases to the tip of the clinical iceberg, and a management exclusively based on modulation of physiology, is finally surging as the safest and most efficacious philosophy in hemorrhagic shock. ATLS^® classification and recommendations on hemorrhagic shock are not helpful because antiphysiological and potentially misleading. Hemorrhagic shock needs to be reclassified in the direction of usefulness and timing of intervention: in particular its assessment and management need to be tailored to physiology.

Concerns of the anesthesiologist: anesthetic induction in severe sepsis or septic shock patients

Septic patients portray instable hemodynamic states because of hypotension or cardiomyopathy, caused by vasodilation, thus, impairing global tissue perfusion and oxygenation threatening functions of critical organs. Therefore, it has become the primary concern of anesthesiologists in conducting anesthesia (induction, maintenance, recovery, and postoperative care), especially in the induction of those who are prone to fall into hemodynamic crisis, due to hemodynamic instability. The anesthesiologist must have a precise anesthetic plan based on a thorough preanesthetic evaluation because many cases are emergent. Primary circulatory status of patients, including mental status, blood pressure, urine output, and skin perfusion, are necessary, as well as more active assessment methods on intravascular volume status and cardiovascular function. Because it is difficult to accurately evaluate the intravascular volume, only by central venous pressure (CVP) measurements, the additional use of transthoracic echocardiography is recommended for the evaluation of myocardial performance and hemodynamic state. In order to hemodynamically stabilize septic patients, adequate fluid resuscitation must be given before induction. Most anesthetic induction agents cause blood pressure decline, however, it may be useful to use drugs, such as ketamine or etomidate, which carry less cardiovascular instability effects than propofol, thiopental and midazolam. However, if blood pressure is unstable, despite these efforts, vasopressors and inotropic agents must be administered to maintain adequate perfusion of organs and cellular oxygen uptake.

[Emergency anesthesia, airway management and ventilation in major trauma. Background and key messages of the interdisciplinary S3 guidelines for major trauma patients]

Patients with multiple trauma presenting with apnea or a gasping breathing pattern (respiratory rate  < 6/min) require prehospital endotracheal intubation (ETI) and ventilation. Additional indications are hypoxia (S(p)O(2)  < 90% despite oxygen insufflation and after exclusion of tension pneumothorax), severe traumatic brain injury [Glasgow Coma Scale (GCS)  < 9], trauma-associated hemodynamic instability [systolic blood pressure (SBP)  < 90 mmHg] and severe chest trauma with respiratory insufficiency (respiratory rate  > 29/min). The induction of anesthesia after preoxygenation is conducted as rapid sequence induction (analgesic, hypnotic drug, neuromuscular blocking agent). With the availability of ketamine as a viable alternative, the use of etomidate is not encouraged due to its side effects on adrenal function. An electrocardiogram (ECG), blood pressure measurement and pulse oximetry are needed to monitor the emergency anesthesia and the secured airway. Capnography is absolutely mandatory to confirm correct placement of the endotracheal tube and to monitor tube dislocations as well as ventilation in the prehospital and hospital setting. Because airway management is often complicated in trauma patients, alternative devices need to be available preclinical and a fiber-optic endoscope should be available within the hospital. Use of these alternative measures for airway management and ventilation should be considered at the latest after a maximum of three unsuccessful endotracheal intubation attempts. Emergency medical service (EMS) physicians should to be trained in emergency anesthesia, ETI and alternative methods of airway management on a regular basis. Within hospitals ETI, emergency anesthesia and ventilation are to be conducted by trained and experienced anesthesiologists. When a difficult airway or induction of anesthesia is expected, endotracheal intubation should be supervised or conducted by an anesthesiologist. Normoventilation should be the goal of mechanical ventilation. After arrival in the resuscitation room the ventilation will be controlled and guided with the help of arterial blood gas analyses. After temporary removal of a cervical collar, the cervical spine needs to be immobilized by means of manual in-line stabilization when securing the airway.

[Emergency anesthesia, airway management and ventilation in major trauma. Background and key messages of the interdisciplinary S3 guidelines for major trauma patients]

Patients with multiple trauma presenting with apnea or a gasping breathing pattern (respiratory rate <6/min) require prehospital endotracheal intubation (ETI) and ventilation. Additional indications are hypoxia (S(p)O(2)<90% despite oxygen insufflation and after exclusion of tension pneumothorax), severe traumatic brain injury [Glasgow Coma Scale (GCS)<9], trauma-associated hemodynamic instability [systolic blood pressure (SBP)<90 mmHg] and severe chest trauma with respiratory insufficiency (respiratory rate >29/min). The induction of anesthesia after preoxygenation is conducted as rapid sequence induction (analgesic, hypnotic drug, neuromuscular blocking agent). With the availability of ketamine as a viable alternative, the use of etomidate is not encouraged due to its side effects on adrenal function. An electrocardiogram (ECG), blood pressure measurement and pulse oximetry are needed to monitor the emergency anesthesia and the secured airway. Capnography is absolutely mandatory to confirm correct placement of the endotracheal tube and to monitor tube dislocations as well as ventilation and oxygenation in the prehospital and hospital setting. Because airway management is often complicated in trauma patients, alternative devices and a fiber-optic endoscope need to be available within the hospital. Use of these alternative measures for airway management and ventilation should be considered at the latest after a maximum of three unsuccessful intubation attempts. Emergency medical service (EMS) physicians should to be trained in emergency anesthesia, ETI and alternative methods of airway management on a regular basis. Within hospitals ETI, emergency anesthesia and ventilation are to be conducted by trained and experienced anesthesiologists. When a difficult airway or induction of anesthesia is expected, endotracheal intubation should be supervised or conducted by an anesthesiologist. Normoventilation should be the goal of mechanical ventilation. After arrival in the resuscitation room the ventilation will be controlled and guided with the help of arterial blood gas analyses. After temporary removal of a cervical collar, the cervical spine needs to be immobilized by means of manual in-line stabilization when securing the airway.

Clinically favourable effects of ketamine as an anaesthetic for electroconvulsive therapy: a retrospective study

In a retrospective chart review, we examined the effects of ketamine, an N-methyl-d-aspartate (NMDA) receptor antagonist, as electroconvulsive therapy (ECT) anaesthetic in patients suffering from therapy-resistant depression. We included 42 patients who received ECT treatment with either ketamine (n = 16) or the barbiturate thiopental (n = 26). We analysed the number of sessions until completion of ECT treatment (used as a surrogate parameter for outcome), psychopathology as assessed by pre- and post-ECT Mini-Mental State Examination (MMSE) and Hamilton Rating Scale for Depression (HAM-D) scores as well as ECT and seizure parameters (stimulation dose, seizure duration and concordance, urapidil dosage for post-seizure blood pressure management). The ketamine group needed significantly fewer ECT sessions and had significantly lower HAM-D and higher MMSE scores afterwards. As expected, the ketamine group needed more urapidil for blood pressure control. Taking into account the limits inherent in a retrospective study design and the rather small sample size, our results nonetheless point towards synergistic effects of ECT and ketamine anaesthesia, less cognitive side effects and good tolerability of ketamine.

Acute lung failure

Lung failure is the most common organ failure seen in the intensive care unit. The pathogenesis of acute respiratory failure (ARF) can be classified as (1) neuromuscular in origin, (2) secondary to acute and chronic obstructive airway diseases, (3) alveolar processes such as cardiogenic and noncardiogenic pulmonary edema and pneumonia, and (4) vascular diseases such as acute or chronic pulmonary embolism. This article reviews the more common causes of ARF from each group, including the pathological mechanisms and the principles of critical care management, focusing on the supportive, specific, and adjunctive therapies for each condition.

The pharmacology of airway management in critical care

This review provides an update on the pharmacology of airway management, emphasizing medications and management strategies widely used in an intensive care unit setting. Induction agents, muscle relaxants, opioids, sedative-hypnotics, and adjunctive agents are reviewed in the context of emergent airway management. Throughout this review, we emphasize the utility of considering a broad set of pharmacologic agents and approaches for airway management of the critically ill patient.

Operational anaesthesia for the management of traumatic brain injury

The primary brain insult that occurs at the time of head injury, is determined by the degree of neuronal damage or death and so cannot be influenced by further treatment. The focus of immediate and ongoing care from the point of wounding to intensive care management at Role 4 should be to reduce or prevent any secondary brain injury. The interventions and triage decisions must be reassessed at every stage of the process, but should focus on appropriate airway management, maintenance of oxygenation and carbon dioxide levels and maintenance of adequate cerebral perfusion pressure. Early identification of raised intracranial pressure and appropriate surgical intervention are imperative. Concurrent injuries must also be managed appropriately. Attention to detail at every stage of the evacuation chain should allow the head-injured patient the best chance of recovery.

Anaesthetic and critical care management of thoracic injuries

Thoracic wounding has been a relatively common presentation of military wounds throughout modern conflict. When civilian casualties are included the incidence has remained constant at around 10%, although the frequency and severity of wounds to combatants has been altered by modern body armour. Whilst thoracic injury has a high initial mortality on the battlefield, those surviving to reach hospital frequently have injuries that only require simple management. In addition to penetrating ballistic injury, blunt chest trauma frequently occurs on operations as a result of road traffic collisions or tertiary blast injury. The physiological impact of thoracic wounds, however, is often great and survivors often require intensive care management and, where available, complex strategies to ensure oxygenation and carbon dioxide removal. This review examines the incidence and patterns of thoracic trauma and looks at therapeutic options for managing these complex cases.

Wherefore ketamine?

PURPOSE OF REVIEW

Ketamine has been repeatedly reviewed in this journal but novel developments have occurred in the last few years prompting an update. Interesting recent publications will be highlighted against a background of established knowledge.

RECENT FINDINGS

In the field of anesthesia, particularly in pediatrics, some contributions have been made concerning intramuscular versus intravenous induction. The need for anticholinergic adjuvants has also been clarified. Neuroapoptosis has been observed in animals and its implications for human subjects are discussed in a general context of neurotoxicity. The most important developments, however, are in the treatment of pain. Neurological and urological side effects strongly question long-term use. Other potentially beneficial effects have also been reported, such as anti-inflammatory and antidepressive effects. There are also indications that ketamine may attenuate postoperative delirium in coronary by-pass patients.

SUMMARY

More questions have arisen than have been answered. Some have very grave implications. The issue of neuroapoptosis must be clarified. The long-term effects must be further investigated. On the bright side the effects on postoperative delirium, as well as the anti-inflammatory and antidepressive effects, might open new vistas for an old drug.

Anesthesia in prehospital emergencies and in the emergency department

PURPOSE OF REVIEW

Recently, notable progress has been made in the field of anesthesia drugs and airway management.

RECENT FINDINGS

Anesthesia in prehospital emergencies and in the emergency department is reviewed and guidelines are discussed.

SUMMARY

Preoxygenation should be performed with high-flow oxygen delivered through a tight-fitting face mask with a reservoir. Ketamine may be the induction agent of choice in hemodynamically unstable patients. The rocuronium antagonist sugammadex may have the potential to make rocuronium a first-line neuromuscular blocking agent in emergency induction. Experienced healthcare providers may consider prehospital anesthesia induction. Moderately experienced healthcare providers should optimize oxygenation, hasten hospital transfer and only try to intubate a patient whose life is threatened. When intubation fails twice, ventilation should be performed with an alternative supraglottic airway or a bag-valve-mask device. Lesser experienced healthcare providers should completely refrain from intubation, optimize oxygenation, hasten hospital transfer and ventilate patients only in life-threatening circumstances with a supraglottic airway or a bag-valve-mask device. Senior help should be sought early. In a 'cannot ventilate-cannot intubate' situation, a supraglottic airway should be employed and, if ventilation is still unsuccessful, a surgical airway should be performed. Capnography should be used in every ventilated patient. Clinical practice is essential to retain anesthesia and airway management skills.

Management of the airway in multitrauma

PURPOSE OF REVIEW

The primary purpose of this article is to highlight the latest airway research in multitrauma.

RECENT FINDINGS

Management of the airway in multitrauma patients is a critical resuscitation task. Prehospital airway management is difficult with a high risk of failure, complications, or both. In-hospital performed conventional oral intubation with manual in-line stabilization, cricoid pressure, and a backup plan for a surgical airway is still the most efficient and effective approach for early airway control in multitrauma patients. Selective utilization of airway maintenance, instead of ultimate airway control in the field, has been suggested as a primary prehospital strategy. Properties of videolaryngoscopes complement standard laryngoscopes. When compared with a Macintosh laryngoscope, the Airtraq and Airwayscope diminish cervical spine motion during elective orotracheal intubation. Penetrating neck injuries are the most frequent indication for awake intubation, whereas patients with maxillofacial injuries have the highest rate of initial surgical airway.

SUMMARY

Risks and benefits of ultimate prehospital airway control is a controversial topic. Utilization of videolaryngoscopes in multitrauma remains open for research. Standardization of training requirements, equipment, and development of prehospital and in-hospital airway algorithms are needed to improve outcomes. Rational utilization of available airway devices, development of new devices, or both may help to promote this goal.

Anaesthesia in prehospital emergencies and in the emergency room

AIMS

To review anaesthesia in prehospital emergencies and in the emergency room, and to discuss guidelines for anaesthesia indication; pre-oxygenation; anaesthesia induction and drugs; airway management; anaesthesia maintenance and monitoring; side effects and training.

METHODS

A literature search in the PubMed database was performed and 87 articles were included in this non-systematic review.

CONCLUSIONS

For pre-oxygenation, high-flow oxygen should be delivered with a tight-fitting face-mask provided with a reservoir. In haemodynamically unstable patients, ketamine may be the induction agent of choice. The rocuronium antagonist sugammadex may have the potential to make rocuronium a first-line neuromuscular blocking agent in emergency induction. An experienced health-care provider may consider prehospital anaesthesia induction. A moderately experienced health-care provider should optimise oxygenation, fasten hospital transfer and only try to intubate a patient in extremis. If intubation fails twice, ventilation should be resumed with an alternative supra-glottic airway or a bag-valve-mask device. A lesser experienced health-care provider should completely refrain from intubation, optimise oxygenation, fasten hospital transfer and only in extremis ventilate with an alternative supra-glottic airway or a bag-valve-mask device. With an expected difficult airway, the patient should be intubated awake. With an unexpected difficult airway, bag-valve-mask ventilation should be resumed and an alternative supra-glottic airway device inserted. Senior help should be called early. In a "can-not-ventilate, can-not-intubate" situation an alternative airway should be tried and if unsuccessful because of severe upper airway pathology, a surgical airway should be performed. Ventilation should be monitored continuously with capnography. Clinical training is important to increase airway management skills.