Primary Training in Hyperbaric Medicine
Physical Aspects of Hyperbaric Medicine
The clinical utilization of alterations in atmospheric pressure dictate that the practitioner comprehend both the beneficial and potentially hazardous aspects of this esoteric environment. Applicable gas laws and their role in hyperbaric medicine will be reviewed.
Mechanisms of Action
Under increased atmosphere pressure, oxygen becomes a potent and dose dependent drug. Six beneficial effects have been identified: hyperoxygenation, vasoconstriction, superoxide radical formation, pressure/volume related effects, neovascularization and antagonism of leukocyte induced reperfusion injury. The scientific elucidation of these mechanisms and their clinical relevance are discussed.
Special emphasis will be placed upon the preparation of the patient for hyperbaric oxygen therapy. The typical emergent referral involves a patient who is incubated, ventilator dependent, with peripheral and central vascular access lines and the possibility of a chest tube. Each of these aspects, as they relate to relative patient isolation and alterations in atmospheric pressure, will be discussed and practiced. Risk factors for hyperbaric oxygen exposure will be clarified and the management of patient complications reviewed in detail.
As a gaseous drug, large doses of oxygen can produce undesirable side effects and drug interactions. The central nervous system and lungs are two most commonly effected organs and their response to hyperbaric oxygen will be reviewed in depth. Special emphasis will be placed on the recognition and management of CNS oxygen toxicity.
Monoplace Chamber Operations
Through a cohesive series of clinical training sessions, the prospective hyperbaric team member will learn and participate in all aspects of the monoplace hyperbaric chamber delivery system. Standard operational protocols will be augmented with ancillary equipment demonstrations and a detailed review of emergency procedures.
Contraindications and Side Effects
Pre-exposure evaluation of risk factors centers around the prevention of pulmonary barotrauma of ascent and the development of a central nervous system oxygen intolerance secondary to high inspired oxygen pressures. The risk-benefit ratio will be discussed, and in the context of the full range of patient states.
Boyle’s law dictates that the volume of a gas is inversely proportional to the pressure exerted upon it. Specifically, the clinical ramifications of this simple principle as it relates to gas bearing anatomy will be discussed. The effects of pressure changes in the middle ear will be examined in detail, and the technical considerations of needle myringotomy will be detailed.
Carbon Monoxide Poisoning/Smoke Inhalation - cyanide poisoning
Carbon monoxide is the most common cause of poisoning in the U.S. In its subtle form the diagnosis is easily missed. A new appreciation for the phenomenon of clinical relapse following conventional oxygen therapy and the potential for long term sequelae has reshaped our understanding of this toxic gas. Current concepts in the pathophysiology of the disease are explored and will include the role of hyperbaric oxygen therapy in pregnancy.
This occupational disease of divers, aviators and tunnel workers is no longer limited in presentation to coastal regions and military institutions. Decompression sickness can result from exposure to any body of water deeper than 30 feet. With more divers flying to and from their dive sites, the potential for illness must be considered, regardless of geographic location. Differential diagnosis, on-site management, evacuation protocols and definitive therapy will be discussed, as will the capabilities of the monoplace chamber.
Cerebral Arterial Gas Embolism
A major life-threatening event, cerebral arterial gas embolization can occur during decompression (in divers and aviators), traumatically in penetrating chest injuries and, most commonly, in the clinical setting secondary to invasive diagnostic, monitoring, or therapeutic procedures. Presentation, differential diagnosis and management guidelines will be reviewed.
Crush Injuries/Compartment Syndrome — other acute ischemias
In an earlier report, it was found that when hyperbaric oxygen therapy was used to arrest the progression of a skeletal compartment syndrome, the cost of management was one-fourth that of surgically treated compartment syndromes. While not proposed in severe cases, the use of HBO in compartment syndrome in selected cases is based on its ability to down-regulate leukocyte receptor sites, decrease tissue edema, hyperoxygenate tissue and overcome diffusion barriers. Evidence for its role in the management of crush injuries is reviewed in detail.
Gas Gangrene (clostridial and nonclostridial) — necrotizing soft tissue infections
Anaerobic infections are among the most challenging infectious disease problems. Optimum management in many instances mandates a combined therapeutic regimen using antibiotics and surgery in combination with hyperbaric oxygen. There is a growing body of evidence to indicate that HBO provides a number of benefits, which include detoxification of the patient, enhanced white cell activity, a synergistic enhancement of selected antibiotics, and improved wound healing.
Acute Thermal Burns
The therapy of burns is directed a minimizing edema, preserving marginally viable tissue, enhancing host defenses and promoting wound closure. Adjunctive hyperbaric oxygen can attack all of these problems directly through a combination of mechanisms. Basic research, controlled clinical studies and cost impact will be reviewed.
Radiation Tissue Damage
It was the consensus of the 1990 National Cancer Institute Conference on Oral Complications of Cancer Therapies that HBO is a standard of care, in conjunction with surgery as indicated, for osteoradionecrosis of the mandible. Further, HBO was recommended in a prophylactic capacity prior to surgical procedures within the irradiated field, in high risk patients. Evidence of a benefit of HBO in soft tissue radiation injury will be included during this presentation.
Selected Problem Wounds; Diabetic Wound Healing — skin grafts and flaps
While not indicated for the support of adequately perfused tissue, hyperbaric oxygen can play an important adjunctive role where hypoxia or decreased microcirculatory flow complicates wound healing. In the compromised host setting, HBO can restore a favorable cellular milieu in which the wound repair process and host antibiotic mechanisms are enhanced. The role of HBO in diabetic foot lesions will be emphasized.
Drawing upon the orthopedic and vascular surgery literature, a number of indicators have served to both predict outcome from various procedures and determine the degree of severity in vascular disease. One particular aspect, tissue oxygen tension , as measured trancutaneously, has been introduced into the hyperbaric oxygen setting as a indicator of the ability to reverse local hypoxia. An algorithmic screening and case-management protocol will be introduced.
Interesting clinical problems and case illustrations will be presented. Cases have been selected which will emphasize key management principles.
Hyperbaric Emergency Procedures
Effective operational practice mandates the ability to recognize potential and actual threats to patient and staff member safety. Examples include sudden deterioration in patient status, equipment malfunction, and hazards within or in close proximity to the hyperbaric facility. Protocols to address each emergency situation will be described, and complemented by several drills, including emergency evacuation of the facility during simulated patient treatments.
The Multiplace Chamber
A presentation will describe the design, installation and operational characteristics of the multiplace hyperbaric delivery system. Chamber nomenclature, air compression options, gas filtration requirements, oxygen delivery systems, fire suppression options, and inside attendance safety will be described. Special attention will be focused on related National Fire Protection Association Standards for safe practice.