Arterial gas embolism

Arterial gas embolism is a major cause of death in diving and the initiating cause (pulmonary barotrauma) usually goes undetected. Caused most often by the expansion of respiratory gases during ascent, it also occurs when the breath is held during ascent from a dive, when there is local pulmonary pathology, when there is dynamic airway collapse in the non-cartilaginous airways and if there is low pulmonary compliance, particularly if this is not distributed evenly throughout the lungs. Boyle's law is the physical law controlling the event. Experimental evidence indicates that intratracheal pressures of about 10 kPa (4 fsw or 1.22 m. or ascending from 170 feet or 51.82 m. to 120 feet or 36.58 m.) are all that's needed for it to happen. Distention of the alveoli leads to rupture, alveolar leakage of gas, and extravasation of the gas into the arterial circuit.

Necrotizing soft tissue infection

Alternative names:  Necrotizing fasciitis; Fasciitis - necrotizing; Flesh-eating bacteria; Soft tissue gangrene; Gangrene - soft-tissue

Definition

Necrotizing soft-tissue infection is a severe type of tissue infection that can involve the skin, subcutaneous fat, the muscle sheath (fascia), and the muscle. It can cause gangrene, tissue death, systemic disease, and death.

Delayed radiation injury to soft tissue and bone

Cancer treatment has improved significantly over the past decade. Although cure of the cancer is still the highest priority of treatment, cancer specialists have come to recognize the ever-increasing importance of quality of life to the cancer survivor. One-half of the estimated 1.2 million new cases of invasive cancer will receive radiation therapy as a part of their cancer treatment. Side effects of this therapy can be very toxic, especially when combined with chemotherapy. Some people are more sensitive to radiation damage than others, and there are no reliable tests available as yet to identify those patients who will experience the worst side effects.

Radiation doses must be adequate to control the cancer; otherwise, there is no purpose in treating the patient. Most radiation cancer specialists or oncologists design their treatment protocols to give the best dose to control the tumor and still have no more than 5% of patients develop severe reactions to treatment. Radiation side effects are generally divided into two categories. First, there are those that happen during or just after the treatment, called acute reactions. Second, there are those that happen months or even years after the treatment, called chronic complications. The acute side effects almost always resolve with time and are treated in such a way as to address the patient's symptoms. For example, when a patient has a cancer of the mouth or throat, it becomes very difficult for the patient to eat during and just after treatment because the lining of the mouth and throat becomes raw and painful.

Selected problem wounds

Problem wounds are those which fail to respond to established medical/surgical management. These wounds usually present in compromised hosts with multiple local and systemic factors which inhibit tissue repair. These include:

• Diabetic Wounds
• Compromised Amputation Sites
• Nonhealing Traumatic Wounds
• Vascular Insufficiency Ulcers

Regardless of etiology, the basic mechanism of nonhealing wounds is an interplay between varying degrees of tissue hypoperfusion and infection. All have the underlying problem of tissue hypoxia and its sequela as common denominators. Tissue oxygen tensions in or near such wounds usually measure below 20 mmHg. In a hypoxic environment, wound healing is halted by decreased fibroblast proliferation, collagen production and capillary angiogenesis. Hypoxia also impairs oxygen-dependent intracellular leukocyte bacterial killing of the most common aerobic organisms found in wound infections and creates the ideal environment in which anaerobic and microaerophilic organisms flourish.

RATIONALE: Hyperbaric oxygen (HBO2) treatment provides a significant increase in tissue oxygenation in the hypoperfused, infected wound. This elevation in oxygen tension induces significant positive changes in the wound repair process. HBO2 promotes wound healing by directly enhancing fibroblast replication, collagen synthesis, and the process of neovascularization. Providing oxygen at the cellular level also increases leukocyte bacterial activity and has a direct lethal effect on anaerobic organisms. In summary, tissue oxygen tension influences the rate of collagen deposition, angiogenesis, and bacterial clearance in wounds. Hypoxia is deleterious and hyperoxia will enhance the wound healing process. HBO2 elevates oxygen tensions in ischemic and infected wound tissue. The greatest benefits are achieved in tissues with compromised blood flow and oxygen supply.

Clostridial Myositis and Myonecrosis

Gas gangrene, anaerobic infections, or necrotizing infections

This disease is caused when the bacteria in the family of Clostridium (e.g., Clostridium perfringens) infects the body tissue. Clostridium bacteria of this type can only live where there is little or no oxygen (i.e., anaerobic conditions). This occurs in damaged or injured tissues where the oxygen supply is low. It is called "gas" gangrene because the Clostridium bacteria release gas that causes swelling in the surrounding tissue.