Since early recorded use of the endotracheal catheter for controlled ventilation of the lung and protection of the airway from aspiration, the protection of airway integrity has been inconsistently obtained and not without significant morbidity.

Trauma is the leading cause of death between the ages of 1 and 40. The three most common causes of trauma related death are inadequate ventilation, inadequate circulation and massive hemorrhage. Thus high priority must be given to airway management, breathing and circulation. The efficiency of the former is essential to optimal circulatory adjustment. No presently available instrument fulfills these needs within a single system.

The physiological range of respiratory rates and heart rates in neonates is approximately 40 per min and 120 per min, respectively, which yields a theoretical ventilation-compression ratio of 1:3ratherthan 1:5.

Thirty-six anesthetized pigs with an average body weight of 4–5 kg were used in the study. After establishing a steady state by artificial ventilation with 100% oxygen, a cardiac arrest was induced by an intravenous injection of potassium chloride. Following the cardiac arrest, the animals were resuscitated with ventilation rates of 30 and 40 per min, respectively, while external cardiac compression was performed at rates between 60 and 160 per min. Randomly selected animals were resuscitated with ventilation-compression ratios of 1:2, 1:3 and 1:4 for 10 min each, 6 animals each were ventilated using a ventilation rate of 30 per min, 40 per min, or positive end-expiratory pressure.

Investigation of High Frequency Jet Ventilation (HFJV) for cardiopulmonary resuscitation (CPR) was initiated to determine whether HFJV may be used as an alternative to conventional intermittent positive pressure ventilation (IPPV) and also to determine whether HFJV may be employed in CPR if cardiac arrest should occur during use of HFJV.

The novel method of HFJV has several advantages over conventional ventilation, namely low airway pressure, no hemodynamic impairment and no need for muscle paralysis. Transtracheal HFJV offers in addition cricothyroid membrane puncture as a fast alternative to tracheal intubation in cases of difficult airway control. It is able to prevent aspiration, and allows direct intrapulmonary drug administration.

Ventilation is an integral part of cardiopulmonary resuscitation (CPR). Early intubation is recommended not only for the sake of better ventilation but also to prevent aspiration since aspiration is a common occurrence during CPR. It probably not infrequently contributes to an unfavorable outcome. Endotracheal intubation is sometimes very difficult especially under field conditions. Cricothyroid membrane puncture or transtracheal puncture with a 14g or 16g catheter needle enables high frequency jet ventilation (HFJV) and can often be performed more easily than intubation.

It has previously been demonstrated that high frequency jet ventilation, via transtracheal cricothyroid membrane puncture, can maintain good gas exchange even during cardiopulmonary resuscitation. When the upper airways were filled with fluid, aspiration could be prevented without a cuffed endotracheal tube when respiratory rates of 100/min or higher and an inspiratory time of at least 50% were used. We have also shown that cricothyroid membrane puncture is relatively easy to perform and produces less tracheal damage than a cuffed endotracheal tube.

In one of our studies, cardio-green dye was mixed into the jet using a Y-connector on the proximal end of the angiocath cannula (Figure 1). In two dogs, the distribution of the dye in the lungs was investigated. It was found that nebulized dye was transported by the jet stream to the most distant bronchi which could be observed. On subsequent autopsy, the dye was found in the most peripheral airways.

Standard CPR, consisting of 60 chest compressions per min with a ventilation interposed after every fifth compression, often allows restoration of spontaneous circulation but cannot be relied upon to preserve the brain during resuscitation attempts. In experimental models, it produces only one-third to one-half of normal cerebral blood flow and cannot sustain EEG activity. Many attempts have been made to augment overall cardiac output during CPR and presumably thereby increase cerebral blood flow. Crile used a pneumatic pressure suit to bind the abdomen and legs, but subsequent investigations found a high risk of hepatic trauma with abdominal binding. Both Wilder and Harris showed in dogs that simultaneous ventilation and compression augment carotid flow. Birch showed in an animal model that prolonged compression increased mean arterial pressure during CPR. Weisfeldt and colleagues of Baltimore have recently extended these findings to man, and combined them into a so-called “New” CPR, which consists of:

a) high pressure ventilation simultaneous with sternal compression;

b) 40 compressions per min;

c) 60% compression duration; and

d) abdominal binding.

Sudden cardiac death is the number one killer in the western world. In the USA alone, CPR attempts are justified in 200,000 cases per year. Recovery of brain function requires immediate initiation and uninterrupted maintenance of artificial ventilation and circulation by basic life support (BLS) until restoration of spontaneous circulation (ROSC) is possible with advanced life support (ALS). Presently recommended standard CPR (SCPR) produces only 6–30% of normal common carotid blood flow. For this reason, a more effective method of prolonged CPR-BLS is necessary in the absence of ALS ambulance services, which is common in rural areas.

Augmentation of blood flow during CPR can be accomplished by intravenous fluid load and epinephrine, which are unavailable to BLS personnel. Sustained abdominal compression in dogs during CPR increases blood flow but produces a high incidence of hepatic trauma. The use of military anti-shock trousers (MAST) during short-term SCPR has been shown to increase common carotid blood flow (CCABF); this, however, has not been evaluated with a long-term model.

Introduction: Although the hemodynamic superiority of open chest cardiopulmonary resuscitation has long been recognized, its advantages with respect to the brain have only recently been investigated. Yashon demonstrated the ability of open chest CPR to maintain EEG activity during prolonged resuscitation. Alifimoff showed improved cerebral reco-very in dogs after open chest CPR. Byrne has demonstrated that internal cardiac massage can provide nearly normal cerebral blood flow in dogs as opposed to the 30% of normal seen during standard CPR, which consists of 60 chest compressions per min with a ventilation interposed after every fifth compression and 50% compression duration.

Introduction: Standard closed-chest CPR (SCPR) produces only 6–30% of normal blood flow. It is unlikely that this can sustain the viability of the brain for more than a few minutes in most CPR attempts, although in occasional cases of human resuscitation external CPR for up to two hours has been followed by recovery of consciousness. Thus various methods have been employed to improve this low perfusion state. It has been shown that abdominal compression by hand or MAST-suit can augment carotid artery blood flow during CPR but causes complications. Openchest CPR (OCCPR) has also been proven to be hemodynamically superior to SCPR. Since neurologic recovery has been studied after prolonged periods of total circulatory arrest but not after prolonged periods of CPR, we compared the prolonged use of SCPR and OCCPR in terms of ability to sustain signs of cerebral function during CPR and permit cerebral recovery after CPR.

From many recent publications and also from a pathophysiologic standpoint, it has become abundantly clear that probably the most important factor determining the outcome of any attempt at resuscitation is the period of time elapsed between the onset of the calamity and the initiation of “CPR.” In most of the reports on the effects of time-related variables the initiation of effective cardiopulmonary resuscitation is usually not clearly defined.

What exactly is meant by “initiation of CPR?” Since 1966 CPR has been instructed according to the “A-B-C-schedule.”

The CPR committee of the Dutch Heart Association currently recommends for the management of sudden cardiac arrest, the initiation of external cardiac compressions before airway control and ventilation, which may be termed the “CAB” sequence. This differs from the ABC sequence, recommended by the American Heart Association, in which the patient is ventilated first. Supporters of the CAB sequence reason that, since most sudden cardiac deaths are due to ventricular fibrillation, the blood in the arterial system should be well oxygenated at the onset of such an episode. We conducted these studies to characterize the decline in arterial blood gases during 5 min of cardiac arrest, followed by external cardiac compressions alone, vs followed by external cardiac compressions with ventilation. In addition, we studied the decline in arterial blood gases and ventricular fibrillation without therapy.

We could obtain good results similar to other groups with a device for cardiac compression and automatic ventilation during CPR. The following paper will not discuss the experience with such a device, but the further development and improvement of a device already used and found to be useful.

The further development seemed to be necessary since we tried to utilize new hemodynamic results important for external cardiac compression and ventilation. Other reasons were problems occurring with its practical use.

The automatic implantable defibrillator is an electronic device designed to continuously monitor cardiac rhythm, identify ventricular fibrillation and deliver corrective defibrillatory discharges, when indicated. Physically similar to early pacemakers, it weights 250 grams and has a volume of 145 cc (Figure 1). All materials in contact with body tissue are biocompatible. The defibrillating electrodes are made from titanium and silicone rubber. One electrode, designed for placement in the superior vena cava near the right atrial junction, is located on the distal end of an intravascular catheter. The second electrode, in the form of a flexible rectangular patch, is placed extrapericardially over the apex of the heart. The outside surface of the apical electrode is insulated to achieve optimal current distribution.

The device is powered by lithium batteries having a projected monitoring life of approximately 3 years or a discharge capability of approximately 100 shocks. The sensing system detects ventricular fibrillation by monitoring a sampled probability density function of ventricular electrical activity.

The effect of positive inotropic agents on circulation and ventricular fibrillation threshold are not fully understood during the influence of metabolic acidosis during circulatory arrest. This is the same case with alkalosis, caused by the over-correction of sodium bicarbonate. Furthermore, the role of calcium during CPR is not clear.

Therefore, we investigated the influence of metabolic acidosis and alkalosis with and without the administration of the positive inotropic substances epinephrine and calcium upon contractility and ventricular fibrillation threshold.

Monitoring of the level of neurological response is an essential component of the diagnostic and therapeutic process in the management of craniocervical injury and neurological catastrophes. When Hippocrates reminded us that “No Head Injury is so mild that it can be neglected,” he cannot have been aware of the significance of the lethal factors of cerebral swelling and intracranial hematoma contributing to poor survival. Neither can he have known how these factors could be detected. Coma scales have evolved to indicate when deterioration is likely and intervention indicated.

Many hospitals use simple grades of responsiveness for their unconscious patients, but the widespread habit of recording the level of response in an abstract manner is as meaningless as measuring temperature in units of feverishness. There is a requirement for a device which can be expressed in numerical terms and, when necessary, related to an analogue or graphical mode.

Ischemic and traumatic brain insults may be followed by pulmonary failure, which is a frequent cause of death in cases of multi-trauma, cardiac arrest and stroke. Pulmonary edema (PE) can occur secondary to events in the central venous nervous system (CNS). This is generally termed neurogenic pulmonary edema (NPE). It is not known which of the following 4 factors of the modified Starling equation of pulmonary edema development are involved in the development of NPE: a) filtration coefficient, that is, increased membrane permeability; b) abnormal hydrostatic pressure gradient; c) abnormal oncotic pressure gradient; and d) blockage or overwhelming of lymphatic drainage (Fig. 1).

Resuscitation of the brain after ischemic-anoxic brain injury remains a controversial topic. There is, however, presently a certain therapeutic optimism in this field. Ours is partly based on the recognition of a post-resuscitation disease, that is, treatable pathologic processes in all organs after restoration of adequate perfusion pressure and arterial oxygenation. Also, Hossmann has shown that neurons can survive longer periods of anoxia than previously assumed.

There have been reports on experimental focal ischemia indicating beneficial effects of barbiturates and moderate hemodilution before and after initiation of focal ischemia. After complete temporary global brain ischemia (GBI), as in cardiac arrest, however, results so far have been conflicting and controversial.

Retrospective studies of the mechanisms of drowning are difficult to make for a number of reasons. First, the severity of the immersion incident is hard to classify; therefore, conclusions drawn from the outcome of a number of incidents grouped together may be erroneous. Second, confusion results from traditional attempts to separate victims into those who immerse in salt water from those who immerse in fresh. This is an analysis of 61 individual cases of immersion published in the last 20 years, but not previously subjected to group analysis such as those published by Modell, Conn and Simcock.

Results

In 61 cases reviewed, males outnumbered females by almost 4 to 1 (48/13), 17 died and 44 survived (Table 1). When placed in age groups, those most at risk fell into the 0–5 years old group, comprising 43% of the total; but this group also contained the greatest proportion of survivors (Figure 1).

There have been 81 patients brought to Treliske Hospital, Truro, UK in the last 6 years, having been rescued from near-drowning. Only 5 have been declared dead on arrival and not treated. We consider that hypothermia is a major factor in patients who have apparently drowned, particularly when it has been known that they were strong swimmers. In 1980, 45% of all drownings had rectal temperatures less than 35°C. The sea temperature around our shores varies between 5°C in January and 15.5°C in September. Hypothermia causes little problem until a central temperature of 35°C or less is reached. Between 35°C and approximately 32°C there is disorientation and incoordination, which may make swimming difficult to maintain efficiently. Below 32°C there is loss of consciousness; when this occurs, the victim's head drops below the water level and drowning occurs just as quickly as in a victim who is unconscious on entering the water.

Recent case reports have shown that persistent hypoxia after the resuscitation of nearly-drowned patients is a major problem. PEEP ventilation could be successfully applied in such a condition. After PEEP valves for manually operated resuscitators became available, the question arose of how beneficial the immediate application of positive end expiratory pressure of 5 cm H2O would be for lungs damaged by either seawater or fresh water. This question was examined by means of standardized animal experiments.

Material and Methods

In four test groups comprising 34 randomly selected young pigs, either 25 ml fresh water/kg body weight, or else 12.5 ml salt water/kg body weight, were instilled by way of an endotracheal tube. This was followed by a period of apnea lasting 4 min and subsequent ventilation with 100% oxygen for a 2 hour period. The 32 animals which survived the first part of the experiment were then subjected to either PEEP or ZEEP ventilation therapy without further medication.