ARTÍCULO ESPECIAL

 

The use of oxygen therapy by means of the hyperbaric chamber in oral and maxillofacial surgery

Empleo de la oxigenoterapia mediante cámara hiperbárica en cirugía oral y maxilofacial

 

 

J.I. Iriarte Ortabe¹, J.M. Batle Vidal², M. Urdiain Asensio⁵, J. Caubet Biayna⁴, M.A. Morey Mas¹, 
J. Collado Lopez³, V. Lasa Menéndez¹, H. Hamdan¹, MªJ. Pastor Fortea³, C. Bosch Lozano⁵, J. Sánchez Mayoral⁴

1 Medico Adjunto, Servicio Cirugía Maxilofacial, Hospital Son Dureta.
2 Director de Medisub. Institut de Recerca Hiperbàrica i Subaquàtica, Clínica Juaneda.
3 Medico Residente, Servicio Cirugía Maxilofacial, Hospital Son Dureta.
4 Práctica Privada. Gabinete Balear de Cirugía Oral y Maxilofacial. Clínica Juaneda.
5 Unidad de Investigación del Hospital Son Dureta. Instituto Universitario de Investigación en Ciencias de la Salud (IUNICS). 
Palma de Mallorca, España.

Dirección para correspondencia

 

 

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ABSTRACT

Hyperbaric oxygen therapy (HBO) is a physical therapeutic modality based on obtaining high partial pressures of oxygen, on breathing pure oxygen inside a chamber at a pressure that is greater than that of the atmosphere.
The object of this revision is to clarify the action mechanisms and the effects of the physical therapy, the problems that may arise and more especially the current indications for its use.
In oral and maxillofacial surgery, HBO is used as complementary treatment for maxillo-mandibular osteitis and osteomyelitis, for necrotizing infections of soft tissue (on a cervical, periodontal, gingival... level), for the prevention (very important) and treatment of osteoradionecrosis, for healing delays (fractures, dental implants, grafts/flaps with difficult viability), for implantological rehabilitation of irradiated oncological patients.
It is necessary to use the protocols that have been established and to generate studies that scientifically support its use; in this sense the lack of consistency that we have found is the studies that have been published could be reduced.

Key words: Hyperbaric oxygentherapy; Osteitis maxillar; Osteomyelitis mandibular.

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RESUMEN

La oxigenoterapia hiperbárica (OHB) es una modalidad de terapéutica física que se fundamenta en la obtención de presiones parciales de oxígeno elevadas, al respirar oxígeno puro en el interior de una cámara a una presión superior a la atmosférica.
El objetivo de esta revisión es clarificar los mecanismos de acción y los efectos de esta terapéutica física, los problemas que puede plantear y sobre todo las indicaciones actuales.
En cirugía oral y maxilofacial, la OHB se utiliza como tratamiento complementario en procesos de osteítis y osteomielitis maxilo-mandibular, en infecciones necrotizantes de partes blandas (a nivel cervical, periodontal, gingival,…), en la prevención (muy importante) y el tratamiento de la osteradionecrosis, en los retrasos de cicatrización (de fracturas, de implantes dentales, de injertos/colgajos de difícil viabilidad), en la rehabilitación implantológica de pacientes oncológicos irradiados.
Es preciso utilizar los protocolos establecidos y generar estudios que sostengan científicamente su utilización; de este modo se podría paliar la poca consistencia de los estudios publicados que hemos encontrado.

Palabras clave: Oxigenoterapia hiperbárica; Osteitis maxilar; Osteomielitis mandibular.

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Introduction

Hyperbaric oxygen (HBO) therapy is a physical therapeutic modality based on obtaining high partial pressures of oxygen, on breathing pure oxygen inside a hyperbaric chamber, at a pressure that is greater than that of the atmosphere. ^23,35 It is a therapeutic technique that uses air for short intervals, or other mixtures of gases, at a pressure that is above that of the atmosphere in order to treat various pathologies.⁸¹ The aim is to use a pharmacological dose of oxygen with a therapeutic effect that can be regulated according to the maximum pressure, the duration of the therapeutic session and the frequency and total number of exposures.

The efficiency of oxygen applied locally has not been demonstrated and, although the pressure at the local source can be high, it cannot be in anyway considered a modality of HBO, not even local one. Neither does ozone therapy modify the partial pressure of oxygen nor does it increase plasma transport.

HBO has been known of for over 60 years, although it has only been used properly for 25. In 1939 Behnke published the first clinical use of HBO for treating decompression sickness. Later on, in the 60s, its capacity for improving tissue oxygenation and for combating anaerobic infections was demonstrated. For many years HBO was administered without any scientific basis, and on many occasions it was indicated inadequately, which logically led to the proper therapeutic function of this technique falling into disrepute. ⁴⁶ As a result of rigorous scientific study and supervision by the ‘Undersea and Hyperbaric Medicine Society (UHMS)’, HBO has now found its proper place.

In Spain the «Comité Coordinador de Centros de Medicina Hiperbárica (CCCMH)» (http://cccmh.com) encompasses ten or so hospital centers offering hyperbaric medicine, among which is Medisub (www.medisub.org), following the recommendations of its European equivalent, the «European Committee for Hyperbaric Medicine (ECHM)».

 

Material and method

As previously explained, HBO consists in administering 100% oxygen (through a mask, helmet or endotracheal tube) to a patient who is exposed to a pressure of 1.3 atmosphere absolute (ATA). This is achieved in a sealed area called a hyperbaric chamber.

These chambers can be of two types: mono- or multiplace. The mono-place hyperbaric chamber is essentially a pressurized plexiglas cylinder that is pressurized with 2 ATA of pure oxygen. These are less costly, but only one patient can be treated at a time and there is a certain risk of deflagration as oxygen is used for pressurization.

The larger area of the multi-place chambers allows for multiple treatments that can reach 6 ATA. They are safer as the method of pressurization is by means of compressed air and medical assistance can be given inside (Fig. 1).

The Medisub hyperbaric chamber (Fig. 10) that we use has a steel cylinder with an external diameter of 1.80 m and it is 3.5 m long. It is divided into two compartments that are linked by large circular doors measuring 80 cm. The main compartment allows the simultaneous treatment of seven seated patients (Fig. 11), or of two trolley patients, and it is equipped so that advanced life support care can be given (Fig. 12). The compartment has three systems enabling intercommunication with the exterior, background music and continuous monitoring in real time. It has a system of hatches with the exterior that enables medication and/or general equipment to be interchanged (Fig. 13). The patient is accompanied at all times by medical staff trained and qualified to deal with any eventuality. Pressurization control during the treatment is carried out from the control panel (Fig. 14) by a professional that has qualified as an operator of hyperbaric chambers and of diving systems and installations. The entire system complies with the security criteria of current legal requirements (O.M.24978, BOE de 22.11.1997).

There are other types of «chambers» that are designed for treating the extremities that are low cost and very versatile. This type of treatment cannot be considered as HBO as the way it acts is not based on the physiological effects that the breathing of pressurized oxygen has, and it can even diminish the delivery of oxygen to the affected member.

Physiological effects and therapeutic mechanisms of HBO

HBO combines two complementary mechanisms. On the one hand there is the high ambient pressure, and on the other pure oxygen is breathed.^23,30,35 This leads to two different effects: one is volumetric given the increase in ambient pressure per se, and the other is a «solumetric » effect as a result of the partial pressure of the oxygen that the patient breathes.

The volumetric effect is due to an increase in the ambient pressure and it is based on Boyle-Mariott’s Law, which claims that in the human organism, an increase in ambient pressure leads to a decrease, at an inverse proportion, in the volume of all the air filled cavities that are not in contact with the airways (digestive tract, middle ear, paranasal sinuses etc.). This effect can be completely reversed when the hyper-pressure is stopped and the atmospheric pressure value is reestablished.

This effect is beneficial, and one of the principal indications of HBO is based on this: the reduction of the volume of the bubbles in gas embolism cases.

With regard to specific cases of gas embolism (in the event of diving accidents), the bubbles of N2 dissolved in plasma behave as exterior isolated cavities, and as a result the increase in ambient pressure decreases volume. The increase in partial O₂ pressure and the decrease in N2 pressure also contribute to accelerating resorption in gas embolisms.

The solumetric effect is due to the increased partial pressure of the oxygen, and it is based on Henry’s Law that claims that breathing pure oxygen in a hyperbaric environment leads to a progressive increase in arterial, venous and tissular oxygen tension; and oxygen arterial pressure values of over 2.000 mmHg can be reached. There is a 20-fold increase in the volume of oxygen that is dissolved and transported by plasma. Most of the therapeutic benefits of HBO are achieved as a result of this solumetric effect. They are:

• Correction of general or local tissular hypoxia by a simple diffusion gradient. In normal conditions O₂ is transported in the erythrocytes. HBO delivers additional O₂, which is dissolved in plasma and it is not subject to the metabolic regulations of erythrocytic oxygen (it can release oxygen in cells even when there is an absence of hemoglobin). Therefore, it is a type of oxygen that is delivered through the capillaries, and transferred by a simple diffusion gradient.

• Correction of local hypoxia by O₂ redistribution. When the hyperoxia caused by HBO is very pronounced, the organism protects itself by producing compensatory peripheral vasoconstriction. This situation is peculiar in that, despite the existence of vasoconstriction, the levels of peripheral oxygen are higher than normal, and as a result this is termed non-hypoxemic vasoconstriction. This vasoconstriction only occurs in healthy tissues, and not in hypoxic tissue, and the latter therefore benefit from the plasmatic volume taken from non-ischemic tissues. Thus the rich are robbed in order to give to the poor, and some authors have termed this the «Robin Hood effect».

• Stimulation of healing and angiogenesis. As we shall see later, HBO reestablishes the formation of granulation tissue that is halted in hypoxic tissue. Alternating hyperoxia/ normoxia is a good angiogenic stimulant.

• Increase in defenses against infections that is produced through different mechanisms:

- Increase in phagocytosis of the neutrophils. This phagocytosis is oxygen dependent. It is important in some chronic infections due to aerobic germs, particularly those produced by Staphylococcus aureus and by Pseudomonas aeruginosa.
- Bacteriostatic action on anaerobic non-spore germs (principally Bacteroides fragilis, Actinomices and Rhizopus).
- Bactericidal action on some anaerobic spore germs (principally on some species of the Clostridium type that cause necrotizing infections of soft tissue).
- The formation of clostridial toxins is blocked. As we will see later, the treatment of gas gangrene is one of the principal indications for HBO and its importance is based on the fact that the early and sudden mortality from gas gangrene is not due to infection or necrosis itself, but rather to the hemolysis provoked by various clostridial toxins. The beneficial effect of HBO is because the production of toxins needs a low oxidation-reduction potential, and the increase in this potential immediately blocks the production of toxins.

• Rapid elimination of carboxyhemoglobin (COHb). COHb that is formed during acute intoxication from CO, forms a link between Hb and CO that is 230 times more stable than the union between oxygen and hemoglobin with which it competes. HBO manages to reduce this stability (the period for eliminating CO in air to the atmosphere is 8-9 hours, while with hyperbaric oxygen at 3 ATA this is reduced to 25 minutes.

It is in this way that hyperbaric oxygen therapy achieves a series of effects (Table 1) that form the basis for its clinical application.

Hyperoxygenation will support tissues that are poorly perfused; the levels of diffusion obtained are sometimes two or three times those achieved under normal pressure oxygenation. ⁷⁸ HBO is a strong vasoconstrictor, and it does not reduce oxygenation, which is very useful for reducing edemas in skin flaps or bone grafts.³⁵ As we have seen, the increase of partial oxygen tension can improve leukocyte bacterial activity.⁴⁸ An oxygen tension of 30 to 40 mmHg is necessary for encouraging fibroblast proliferation and the development of a collagen matrix; HBO achieves these levels in hypoxic tissues.⁴¹ The collagen matrix supports the growth of new capillaries; this neovascularization has been demonstrated in histological studies of flaps treated with HBO.^49,63 HBO increases the formation of hard tissue such as dentine or enamel in growing teeth,³¹ as well as the production of bone matrix,⁶⁴ and it increases bone mineralization. ^32,65 In addition the increase in osteoclastic activity induced by HBO is the key for remodeling necrotic bone tissue, which is fundamental when treating osteomyelitis and osteoradionecrosis.⁷⁶

HBO Complications

These have been related to the toxic effects of oxygen and to changes in pressure. These are very infrequent (1 case in every 10 to 15000 treatments) and tending to arise only after very long exposure (more than 3 hours), or when pressures higher than normal are applied. In any event, these are slight and transitory. The experience of our reference center Medisub, does not include any important complications during the ten years it has been operating. However the following have been described:

• Barotraumatic lesion with regard to the volumetric effect of HBO. These can affect the eardrum, paranasal sinuses, hollow cavities and lungs.⁶⁹ A series of preventative measures should be applied such as keeping the ears clean, using decongestives and Valsalva’s maneuver.³⁵ In those cases in which the patient is dazed or unconscious, a feasible solution would be to place a needle or catheter for myringtomy, or even drainage tubes.²⁷

• Convulsion fits. High oxygen pressures can cause irritation to the cortex and tonic-clonic convulsions can develop^24,38,88 in approximately 1 out of every 2000 patients exposed.⁶⁹ Despite being rather spectacular, they are of little importance as they stop as soon as the patient’s HBO mask is removed. There are no sequelae, except for a slight postepileptic aura that can last various minutes. Once again this risk can be minimized if certain rules are followed with regard to time and pressure limits.

• Ocular effects: exposure to hyperbaric oxygen at 2.5 ATA causes a constriction of the retinal vessels, of the arterioles by 9.6% and of the venoles by 20.6%.⁸³

- In some cases retrolental fibroplasia has been described (cataracts); this only occurs when mono-place hyperbaric chambers are used in which the ambient air is pure oxygen. Retrolental fibroplasia, which can occur in the immature eyes of infants when subjected to high concentrations of oxygen in incubators, does not occur in adults.

• Acute pulmonary edema. Recently three cases of acute pulmonary edema have been reported, one resulting in a fatality, in cardiac patients given HBO treatment as a result of diabetic foot problems. It is therefore considered with caution for patients with cardiac insufficiency or low ejection fractions. Patients with pulmonary disorders and/or with chronic bronchial problems (COPD) should be more carefully observed as, given the obstruction factor, they can suffer an implosive effect of the alveolar spaces during compression, and an explosive effect in the lungs during decompression. While theoretically this is a possible effect, no cases have arisen and nothing has been published to this effect.

Contraindications to HBO

There are few absolute contraindications to hyperbaric oxygen therapy; the most important would be the existence of untreated pneumothorax. Previous thoractomies, a history of spontaneous pneumothorax or a predisposition to convulsions, can constitute a strong contraindication to the application of HBO. In urgent life-threatening cases special precautions can be adopted.

Infectious disease and catarrh of the upper respiratory tract, acute or chronic blocked sinus disorders (due to ORL problems described), gas dyspepsia, cardiac insufficiency or low ejection fractions and claustrophobia can be relative or temporary contraindications that can easily be resolved. Some authors^12,43 believe that the high cost of the treatment and the extended time required in some protocols should be considered as a relative «contraindication», and that priority should be given to other procedures; some authors achieve better economic results adapting the application protocols. ²⁰

General indications for HBO

The fact that HBO is recommended in different situations, with different clinical and scientific support makes establishing the different indication levels necessary:

• Preferential indications. Diseases for which HBO represents the only efficient etiological treatment, or if its effect is essential, in conjunction with other therapeutic interventions.

• Complementary indications. Diseases in which HBO is neither indispensable nor essential, but where there is a beneficial effect that has been contrasted in clinical and experimental studies.

• Experimental indications. Situations in which HBO can have a therapeutic effect that is acceptable or interesting, with regard to a certain aspect of the disease, based on a consistent therapeutic hypothesis, with a control system and a defined and applicable system for evaluating results within the context of controlled studies. The general indications of HBO are reflected in Table 2.

HBO is the only etiological treatment for gas embolisms of whatever origin, for gas expansion syndrome of the lungs and for decompression sickness from diving. It is the treatment of choice, together with other measures, for acute intoxication from carbon monoxide and gas gangrene.

It is useful as adjunctive therapy for necrotizing infections of soft tissue, refractory chronic osteomyelitis and osteoradionecrosis, and for long-term healing disorders that are secondary to peripheral vasculopathies such as diabetic foot,^11,50 as the risk of amputation is reduced by a third,⁶⁹ and for extensive burns.10 It is also very useful for increasing the survival of medium or large flaps.⁵¹

HBO is also being applied in an experimental fashion, with encouraging results, for celebral post-anoxic brain syndromes, for acute occlusive retinopathies and, with less success, for multiple sclerosis. It can also be efficient for treating migraines although the effect is not prophylactic.^25,71

It is also indicated as coadjuvant therapy in sport. Borromeo and cols.⁴ carried out a randomized double blind study on 32 patients that had suffered acute ankle sprains applying HBO at 2.0 ATA and comparing this with a placebo. The improvement in articular function was greater in the HBO group than in the placebo group.

A considerable problem that was observed in this revision, is the lack of consistency of the studies published as there are very few random studies, the quality of the studies is variable and the methodology is poor. Only small numbers of patients are included in the studies, and there are different inclusion criteria... Giving a better scientific definition of the indications for this therapeutic technique is therefore complicated.

 

Indications for HBO in oral and maxillofacial surgery

Within the general framework of indications, HBO has been used as complementary therapy in oral and maxillofacial surgery for osteitis and osteomyelitis of the maxilla and mandible, for necrotizing infections of soft tissues (cervical, periodontal, gingival,...), for the prevention (very important) and the treatment of osteoradionecrosis, in healing delays (fractures, dental implants, grafts/flaps with difficult viability), for implantological rehabilitation in irradiated oncological patients.

Osteitis and osteomyelitis of the maxilla and mandible

Some types of osteomyelitis become refractive and are stubborn to all of the usual treatments (surgical debridement and appropriate antibiotic treatment for at least six weeks).

These developments that are difficult to deal with are due to resistance mechanisms being adopted by the germ and the inefficiency of defense mechanisms in an ischemic, edematous and hypoxic territory with low bioavailability of antibiotics; in addition, the existence of low partial pressures of oxygen reduces the phagocytic capacity with regard to bacteria.

HBO has demonstrated its efficiency for increasing local defenses, stimulating oxygen-dependent phagocytosis of polymorphonuclear neutrophils and having, on occasions, an anti-infectious and bacteriostatic effect on certain germs.⁵²

HBO is considered as adjuvant therapy for debridement and antibiotic treatment. Its use is not essential, although there are certain works, in humans as well as in animals, that have shown how better results have been obtained using it.^{5,17,21,53,61}

As a protocol, daily sessions of 60 to 90 minutes are recommended with oxygen at 100% at 2.2 and 2.4 ATA for at least two weeks.⁵

Our first clinical case shows how it was used as coadjuvant treatment of BHO in a case of mandibular osteomyelitis that developed into osteitis with a high fracture risk.

Necrotizing infections of soft tissues of the head and neck

The term necrotizing infection of soft tissue refers to a spectrum of entities with a clinical course of necrosis of deep soft tissue, which originate as infective microorganisms. This process has been given numerous names among which are necrotizing fasciitis, gas gangrene, Fourniers gangrene, etc.

All these diagnoses have the same clinical management: urgent surgical debridement, intensive medical support and antibiotherapy in order to try and identify the causative agent.

The microbiological examination shows a polymicrobial infection in more than 82% of cases, where we find: mixed anaerobic flora (30%) Staphylococcus aureus (20%), Escherichia coli (20%) Enterococci (18%) coliforms (14%), Staphylococcus pyogenes (14%), Pseudomonas (11%) y Clostridiums (9%).

Mortality rates vary between 9% and 76%, the average rate being around 30%. Survival in these patients increases 9 times when HBO is included in the treatment.⁸⁶

For patients with gas gangrene (Clostridial myonecrosis) there seems to be no doubt as to the indications being not only preferential, but also urgent.

It is very important to bear in mind that its application in these cases should not entail leaving or delaying antibiotic or surgical treatment.

HBO is of great benefit for treating clostridial myonecrosis, as it has been demonstrated that clostridium stop growing at 3 ATA pressure, although this effects ceases on returning to normal ambient pressure.⁸² In vitro studies show that HBO has a bacteriostatic effect, although this beneficial effect is inhibited by the presence of a catalase present in the blood and in devitalized muscle, so for HBO to work at its best, debriding the area and eliminating hematic remains and necrotic tissue is necessary.^9,40,45

In anaerobic infections, the increase in the pressure of oxygen in the blood generated by the HBO will be bactericidal and it will stop the production of the Clostridium alpha toxin although the O₂ levels achieved will not be bactericidal.⁸⁶

In 1961 Brummelkamp⁹ published the first clinical study of this effect on 4 patients in which clostridial myonecrosis progressed in spite of surgery and antibiotic therapy. HBO achieved a rapid improvement, and in 4 cases this was spectacular. In addition, in a revision of 20 clinical series that included more than 1200 patients, it was reported that HBO reduced mortality from 45% without HBO to 23%.⁷⁰ Similar results were found by Demello and cols¹⁹ (mortality in dogs was reduced from 30 to 5% with HBO)

A very important issue is the best moment for administering HBO in these patients. If it is easily available, its prompt use before surgery could help with the discrimination of healthy tissue and reduce the production of the toxin, keeping the patient more hemodynamically stable. If on the other hand HBO cannot be started during the first 24 hours, initial debriding should first be carried out. The protocol advised for Clostridial myonecrosis is 2 to 3 daily sessions of 90 minutes with oxygen at 100% and 3 ATA for 5 to 7 days.⁸

In addition to debriding and HBO, appropriate antibiotic therapy is essential and this should include penicillin G, clindamycin and metronidazole and the gram (-) anaerobes that are frequently associated.

Necrotizing fasciitis of the neck is a polymicrobial infection of the head and neck that is very severe and mortal on occasions. It is characterized by a dissemination of the infection along facial planes affecting the skin, subcutaneous cellular tissue, fascias, and on rare occasions muscles. The personal factors leading to a predisposition to this type of infection are diabetes mellitus, renal disease, peripheral cardiovascular and vascular disease, cirrhosis and obesity. Necrosis is secondary to the synergic effect of the enzymes of the causative bacteria.⁸⁷

Treatment consists in rapid surgical debridement and the cleaning of necrotic tissue, vital maintenance (tracheotomy in 81% of cases, intensive care, etc.) wide spectrum antibiotherapy and secondary reconstruction of the defect.

It has been postulated that HBO is very efficient as adjuvant therapy, reducing mortality by 50%, reducing the amount of tissue to be debrided^68,77 and of hospital stays by at least 20 days,^26,87 although for some its efficiency has yet to be rigorously established.⁸⁹

Starting HBO as soon as possible after the first debridement is recommended together with the administration over 24 hours of three 90 minutes sessions of 100% oxygen at 3 ATA, followed by 2 daily session until granulation tissue is achieved.^2,86

Osteoradionecrosis

Osteoradionecrosis (ORN) is a late complication of radiotherapy. It is a chronic collateral effect that is not cured spontaneously and that currently has an incidence rate of 4%.

Biologically the process is characterized by inadequate repair and tissue re-growth, and a reduction of the vascular potential of the tissues. Hypovascularity reduces cellular activity, the formation of collagen and the repair of a wound as a result of the capacity of the fibroblasts for forming collagen being reduced.

The risk of ORN increases when bone receives more than 65 Gy. The mandible tends to be the bone that is most affected as a result of endothelial damage to the intraosseous blood vessels, which are relatively scarce. This procedure tends to take many months and even years to develop, with necrosis being produced when the bone suffers bacterial infection. While it is believed that dental caries, periodontal disease, dental extractions or mandibulotomies are the cause, nearly a third of ORN cases appear spontaneously.

ORN is not a primary infection of irradiated bone; microorganisms only play a role in the contamination process if there is the following sequence: radiation, hypoxia, tissue death and a chronic wound that does not heal.⁶⁰

The main treatment of ORN is surgical debridement; all devitalized tissue should be radically eliminated.¹²

The use of HBO as complementary treatment for the damage produced by irradiation began in 1973.^{7,16,17,29,30,37,54} Using a standard protocol that includes surgery, antibiotherapy and HBO, Marx^59,60 showed the efficiency of HBO for treating osteoradionecrosis. In a randomized prospective study using penicillin and HBO in previously irradiated mandibles, he showed how HBO reduced the development of ORN following dental extraction in a statistically significant fashion;⁵⁶ other studies showed an important reduction in the number of complications.^55,57,59

For some^1,75 the use of hyperbaric oxygen in ORN is a motive of controversy; HBO cannot revitalize necrotic bone that should be extracted (sequestrectomy). Hao39 has shown how HBO on its own is efficient if combined with a sequestrectomy, although surgical debridement may be minimized. Nevertheless, HBO can be useful when the ORN process is detected in its initial phases before exposure of the bone,^58,72,84 and it can be even more beneficial if used as a preventative measure.³¹

The protocol used in ORN treatment³⁴ entails 30 HBO sessions after which the results obtained are evaluated. In uncomplicated cases another 30 sessions are given.

For reconstructing the defect generated 20 HBO sessions are required before surgery and 10 after. A minimum 20 sessions are considered necessary for neovascularization to occur in the irradiated bone.⁵⁵ This was followed with the 2nd clinical case presented.

With regard to prevention of ORN, a classic protocol is used for patients that require dental extractions (20 sessions of presurgical HBO and 10 postsurgical at 2.2-2.4 ATA, 60 to 90 minutes) with excellent results for some authors14 and insignificant ones for others.⁷⁹

Other complications after radiotherapy

Recently, the efficiency of HBO for treating post-radiotherapy complications of the head and neck, resistant to the normal treatment has been demonstrated.⁶² DeRossi and cols²² showed how there was a significant improvement in subjective xerostomia of irradiated head and neck patients following 20 sessions of HBO.

Implantological rehabilitation in irradiated oncological patients

Placing dental implants in previously irradiated oncological patients has been considered for a long time as an absolute contraindication.

Towards the end of the 80s and the beginning of the 90s studies using animals began to appear showing the integration of implants in irradiated bone.^6,42,67,74 On the basis of Marx’s studies,^55,57 who analyzed osseointegration surfaces at four months in normal and irradiated bone, hyperbaric oxygen began to be used to achieve neoangiogenesis, increased activity of fibroblasts and oxygen pressure in previously irradiated hypoxic tissues.

According to Beumer and cols3 the predictability of dental implants placed in irradiated bone depends on the anatomical area chosen, the dose received and the use of HBO.

A protocol proposed by Granström^28-30,34-36 which has been unanimously accepted, consists in 30 sessions, 20 before placing the implants and 10 post-surgical sessions with hyperbaric oxygen (100% oxygen at 2.4 ATA) each session lasting 90 minutes.¹³ Granström considered that the maximum stimulation for neovascularization and for fibrosis occurred after 20 to 30 hours of exposure to oxygen at 2-2.⁴ ATA: The object of the postoperative sessions is to reduce the dehiscence of sutures, encouraging the formation of collagen and eliminating/reducing to the maximum hypoxia in the surgical bed.²⁹ The failure of implants in irradiated patients in his hospital was 58% and, following the application of this hyperbaric oxygen protocol, the loss of implants was reduced to 2.6%.³¹

Following the application of HBO, a series of studies appeared showing levels of osseointegration in irradiated bone^33-35,66,80 and even in microvascularized irradiated bone⁴⁶ identical to normal bone.

On the other hand, we should consider that implants placed in bone could be subjected to radiotherapy. Irradiation of the implants leads to overdosing, and tissues on the radiation side and infront of the implants receive a higher dose (120%) than those situated behind (80%).³⁰ The dose is increased approximately by 15% 1mm from the implant^.85 When radiotherapy is applied using both opposite fields, this effect is reduced considerably.³⁰ This accumulated data of clinical experience in irradiated patients with metallic structures suggests that there are no negative effects.^15,73

Implantological rehabilitation

HBO has also been applied in cases where osseointegration of dental implants has been delayed in non-integrated patients. We would like to highlight the case in which 6 mandibular implants were placed, but 3 of these showed signs of lacking bone integration after a week. After 10 sessions of HBO, bone consolidation was observed by means of radiology (Fig. 9).

 

Conclusion

Oral and maxillofacial surgeons are familiar with and they use hyperbaric oxygen. This was shown in a study carried out in the United Kingdom in 2005⁴⁴ that showed how most surgeons considered HBO as part of the treatment for osteoradionecrosis, but it was not used as preventative treatment, (HBO protocol for patients requiring dental extractions in irradiated areas); even so, only half of those in the survey used HBO in protocols for the insertion of implants in irradiated tissue, and very few were familiar with the method for applying this therapy.

We have seen how HBO is used as complementary treatment in oral and maxillofacial surgery in osteitis and osteomyelitis, in necrotizing fasciitis of the neck, in the prevention (very important) and in the treatment of osteoradionecrosis, in healing delays (of fractures, dental implants, of grafts/flaps with difficult viability), in implantological rehabilitation in irradiated oncological patients.

We should therefore think more often in terms of applying HBO as a therapeutic complement for these indications, and serious studies should be carried out to show its efficiency.

On making this revision we have seen the lack of consistency in the studies published: very few studies are randomized, the quality is variable, the methodology is poor, the number of patients is low, and there is different criteria for inclusion... Defining the indications of this therapeutic technique scientifically is thus complicated.

Clinical case 1

A fifty-two year old patient fitted three days previously with an implant in the third quadrant (Fig. 16), attended our service because of the onset of hypoesthesia of the lip and chin on left side on the fourth day, and cervico-facial cellulitis on left side. The implant was removed with LA and considerable purulent material was removed. A diagnosis and treatment of postimplant osteomyelitis of the mandible was established (Fig. 15). Progress was satisfactory, but after two months the patient complained of pain on masticating; a new orthopantomography showed an area of considerable osteolysis (Fig. 17), which was corroborated with a CAT scan (Fig. 2), and a fracture risk. A treatment plan was established that consisted of 5 sessions of HBO, surgery with sequestrectomy, curettage, microbiological culture (that proved negative) and 15 sessions of postsurgical HBO. The result was very satisfactory (Fig. 3), with a near ad integrum recovery of the mandibular anatomy.

Clinical case 2

A patient irradiated two years previously because of a cavity neoplasm, attended our department as a result of a pathological mandibular fracture because of ORN (Fig. 4) and a cutaneous fistula (Fig. 5). A treatment protocol using HBO was established, and the patient underwent 20 sessions of HBO before the surgery. The reconstruction of the defect was carried out with an osteocutaneous flap of microvascularized fibula (Fig. 6), with a satisfactory clinical result (restoration of the masticatory function and disappearance of the fistula) (Fig. 8) and a satisfactory radiological result (Fig. 7).

 

 

Dirección para correspondencia
Dr. José Ignacio Iriarte Ortabe
c/ Calvia 18, chalet B-8
07015 Palma de Mallorca (Baleares), España
ji.iriarte@telefonica.net

Recibido: 2.11.2005
Aceptado: 21.11.2005

 

 

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