Potentially reversible airway obstruction, hypoventilation, apnea, blood loss, pulselessness (cardiac arrest) and brain injury are among the leading causes of death resulting from accidents, heart attacks and other medical emergencies. The leading causes of preventable sudden death before old age are ventricular fibrillation (in patients over age 44) from asymptomatic ischemic heart disease; nontraumatic accidents (e.g., drowning, poisoning); and trauma (in patients under age 38) caused by the violence of main or accidents.
Irreversible brain damage may occur when cessation of circulation (cardiac arrest) lasts longer than a few minutes or after trauma, when severe hypoemia or blood loss remain uncorrected. However, the immediate application of modern resuscitation is often capable of preventing biologic death. Resuscitative measures can be initiated anywhere without the use of equipment, by trained individuals, ranging from the lay public to physician specialists.
There were few immediately applicable effective emergency resuscitation techniques available before the 1950's, when modern respiratory resuscitation was pioneered; modern circulatory resuscitation began in the 1960's, and therapeutically promising research on brain resuscitation began in 1970. The latter work has extended to cardiopulmonary resuscitation (CPR). Resuscitation from circulatory shock has a longer history than that from cardiac arrest. Intensive care (long-term resuscitation), essential for optimal outcome after emergency resuscitation, was initiated in Scandinavia and Baltimore in the 1950's and pioneered by several groups around the world in the 1960's.
The development of modern CPR has been based largely on ideas conceived or accidently discovered many years ago, which were rediscovered and re-explored since the 1950's. These include intermittent positive pressure artificial ventilation (IPPV); mouth-to-mouth breathing; jaw-thrust; open chest cardiac resuscitation; internal defibrillation; tracheal intubation; external CPR; external defibrillation with direct current; and pathophysiologic research on dying and resuscitation.
The history of modern CPR can be summarized according to a series of landmark developments during the past 25 to 30 years: Proof that ventilation with the operator's exhaled air is physiologically sound proof of the ventilatory superiority of exhaled air ventilation (without equipment) over manual chest-pressure arm-lift maneuvers; studies showing why soft-tissue obstruction of the upper airway in unconscious patients could be prevented or corrected by backward tilt of the head, forward displacement of the mandible, and opening of the mouth; proof of the ventilatory superiority of exhaled air ventilation over chest pressure methods in children; rediscovery and development of external cardiac compression; demonstration of the need to combine positive pressure ventilation with external cardiac compression; intrathoracic electric defibrillation of the heart in human patients; the concept of the heart too good to die; external electric defibrillation of the heart in humam patients; electric cardiac pacing; proof of the feasibility of teaching CPR to the lay public; proof that lay people in the field will perform mouth-to-mouth breathing and CPR production of realistic training aids since 1960; and agreements on details of techniques and teaching methods through many national committees and international symposia.
Thus, over the past 30 years, old techniques have been refashioned into new systems. CPR works, and thousands of lives could be saved each year if enough individuals were properly trained in resuscitation. Clinical results depend heavily, however, upon perfection and uniformity of training and appropriate stress given to the importance of initiating resuscitation techniques at the earliest possible moment.
Life supporting first aid comprises basic measures, without the use of equipment, to be learned by the general public. They include selected components of CPR (head-tilt, open mouth, jaw thrust) and direct mouth-to-mouth and mouth-to-nose ventilation. They do not include external cardiac compressions (ECC). Beyond CPR, life supporting first aid includes control of external hemorrhage (by manual compression, elevation and pressure bandage); rescue pull (extrication of the victim from a wreck); and positioning to maintain open airway, combat shock and prevent further injury.
The most common site of airway obstruction is hypopharyngeal, occurring in comatose patients when the relaxed tongue and neck muscles fail to lift the base of the tongue from the posterior pharyngeal wall, when the patient's head is in the flexed or mid-position. Opening the airway is therefore the most important measure in resuscitation. Sometimes additional forward displacement of the mandible is required to produce this stretch. The combination of the backward tilt of the head, forward displacement of the mandible and opening of the mouth constitutes the triple airway maneuver. In about one-third of unconscious patients the nasal passage is obstructed during exhalation because of valvelike behavior of the soft palate; moveover, the nose may be blocked by congestion, blood or mucus. When the chin is sagging, inspiratory efforts may suck the base of the tongue into an obstructing position. Airway obstruction by the base of the tongue depends upon position of the head and jaw and can occur regardless of whether the patient is lateral supine or prone. Although gravity may aid in the drainage of liquid foreign matter; it does not relieve hypopharyngeal soft tissue obstruction, and maneuvers to lift the base of the tongue, as described above, are required.
Another cause of airway obstruction is the presence in the upper airway of foreign matter such as vomitus or blood, which the unconscious patient cannot eliminate by swallowing or coughing. Laryngospasm is usually caused by upper airway stimulation in the stuporose or lightly comatose patient. Lower airway obstruction may be the result of bronchospasm, bronchial secretions, mucosal edema, inhaled gastric contents, or foreign matter.
Airway obstruction may be complete or partial. Complete obstruction is silent and leads to asphyxia (hypoxemia plus hypercarbia) apnea, and cardiac arrest (if not corrected) within 5 to 10 minutes. Partial obstruction is noisy and must also be promptly corrected by either the patient or the rescuer, depending on the amount of air flow, as it can result in hypoxic brain damage, cerebral or pulmonary edema or other complications; and may lead to exhaustion, secondary apnea and cardiac arrest.
Emergency oxygenation of the non-intubated patient is an art that is best acquired through guided clinical experience. Measures for emergency airway control are being improved continuously. These measures should be practiced to perfection on manikins.
Recognition of acute airway obstruction must go hand in hand with therapeutic action, step by step, taking into account the number of personnel available, their training and the possible complications of various therapeutic maneuvers. The airway control measures are intended primarily for the unconscious patient whose treatment requires rapid stepwise progression until the obstruction is controlled.
If the victim is unconscious, backward tilt to the head, forward displacement of the mandible, or both, prevent hypopharyngeal obstruction by the base of the tongue. Either maneuver stretches the tissues between the larynx and mandible, and thereby lifts the base of the tongue from the posterior pharyngeal wall.
Emergency oxygenation attempts in the unconscious patient should start with backward tilt of the head (and/or, in addition, if necessary, jaw thrust and opening of the mouth). If the airway remains obstructed, with or without breathing efforts, add positive pressure inflation attempts.
For direct mouth-to-mouth ventilation using head-tilt and/or jaw thrust, the practitioner should position himself at the side of the patient's head.
Backward tilt of the head, jaw thrust and opening of the mouth can be practiced on manikins, and patients who require artificial ventilation.* FNT *This background material has been derived from Safer, P. Cardiovascular Cerebral Resuscitation, Stavanger, Norway, Asmund S. Laerdal, Philadelphia PA, Saunders (Dist.) (1981), World Federation of Anesthesiologists.
Until now, inextricably associated with the practice of CPR has been the often unpleasant and unavoidable direct mouth-to-mouth contact between victim and CPR practioner.