The effect of atmospheric pressure on the bond strength of composites.

Background: In the current study, we investigated the effect of atmospheric pressure change on the microtensile bond strength of direct and indirect composite restorations to the teeth. Materials and Methods: A total of 16 extracted teeth were prepared after crown cutting and randomly divided into four groups. The study groups included: 1) direct restoration (Filtek™ Z250 Universal Composite Restorative System, 3M, United States) at constant pressure (control); 2) direct restoration in variable pressure; 3) indirect restoration (Z250 composite) at constant pressure (control); and 4) indirect restoration at variable pressure. Then, samples were subjected to thermal cycles. Variable pressure groups were pressurized to 0 to 5 atmospheres for 96 cycles inside the hyperbaric chamber, followed by measuring the microtensile bond strength of the specimens. Results: The mean of microtensile bond strength in both direct and indirect variable-pressure groups was significantly lower than their counterpart control groups. There was no significant difference between direct and indirect restorations in constant and variable pressure. The failure mode of the samples in the control groups was often mixed, while in the pressure groups, it was dominated by adhesive. Also, microscopic examination of restoration interfaces showed that the number and volume of voids in variable pressure groups were much more than the control groups. Conclusion: Regardless of the type of restoration, changing the atmospheric pressure is effective on the bond strength of the restorations to the teeth.

Dysbarism: An Overview of an Unusual Medical Emergency.

Dysbarism is a general term which includes the signs and symptoms that can manifest when the body is subject to an increase or a decrease in the atmospheric pressure which occurs either at a rate or duration exceeding the capacity of the body to adapt safely. In the following review, we take dysbarisms into account for our analysis. Starting from the underlying physical laws, we will deal with the pathologies that can develop in the most frequently affected areas of the body, as the atmospheric pressure varies when acclimatization fails. Manifestations of dysbarism range from itching and minor pain to neurological symptoms, cardiac collapse, and death. Overall, four clinical pictures can occur: decompression illness, barotrauma, inert gas narcosis, and oxygen toxicity. We will then review the clinical manifestations and illustrate some hints of therapy. We will first introduce the two forms of decompression sickness. In the next part, we will review the barotrauma, compression, and decompression. The last three parts will be dedicated to gas embolism, inert gas narcosis, and oxygen toxicity. Such an approach is critical for the effective treatment of patients in a hostile environment, or treatment in the emergency room after exposure to extreme physical or environmental factors.

Prevalence of Headache Attributed to Airplane Travel Among Medical Students in Brazil.

BACKGROUND: Headache attributed to airplane travel is a rare form of headache that develops exclusively during airplane travel. It is characterized by occurring during takeoff, landing, or both, and improves spontaneously within 30 minutes after the ascent or descent of the airplane is completed. OBJECTIVES: Our objectives were to determine the prevalence of headache attributed to airplane travel among medical students who traveled by plane, the time of flight when it occurred, and the emotional state of passengers on new trips. METHODS: The study was prospective, cross-sectional, using a non-random sample of medical students who traveled by plane. In total, 155 passengers who traveled by plane on at least 3 flights, regardless of duration were interviewed. RESULTS: Headache during flight occurred 3 or more times in 7.5% (80/1070) of the trips and 14.2% (22/155) of the passengers, especially during takeoff or landing (17/22; 77.3%), having a stabbing character and lasting less than 30 minutes. The headache improved spontaneously at the end of the landing phase (17/22; 77.3%). When traveling again, 68.2% (15/22) of passengers traveled normally, despite previous painful experience. CONCLUSIONS: This study demonstrated that headache attributed to airplane travel is not as rare as previously thought, being predominant during takeoff or landing. In addition, despite the bothersome feeling, most passengers who experienced this headache traveled normally, despite previous painful experience.

Airway management: induced tension pneumoperitoneum.

Pneumoperitoneum is not always associated with hollow viscus perforation. Such condition is called non-surgical or spontaneous pneumoperitoneum. Intrathoracic causes remain the most frequently reported mechanism inducing this potentially life threatening complication. This clinical condition is associated with therapeutic dilemma. We report a case of a massive isolated pneumoperitoneum causing acute abdominal hypertension syndrome, in a 75 year female, which occurred after difficult airway management and mechanical ventilation. Emergent laparotomy yielded to full recovery. The recognition of such cases for whom surgical management can be avoided is primordial to avoid unnecessary laparotomy and its associated morbidity particularly in the critically ill.

Effects of early surgical exploration in suspected barotraumatic perilymph fistulas.

OBJECTIVES: Treatment of traumatic perilymph fistula (PLF) remains controversial between surgical repair and conservative therapy. The aim of this study is to analyze the outcomes of early surgical exploration in suspected barotraumatic PLF. METHODS: Nine patients (10 cases) who developed sudden sensorineural hearing loss and dizziness following barotrauma and underwent surgical exploration with the clinical impression of PLF were enrolled. Types of antecedent trauma, operative findings, control of dizziness after surgery, postoperative hearing outcomes, and relations to the time interval between traumatic event and surgery were assessed retrospectively. RESULTS: All patients had sudden or progressive hearing loss and dizziness following trauma. Types of barotrauma were classified by the origin of the trauma: 4 external (car accident, slap injury) and 6 internal traumas (lifting, nasal blowing, straining). Surgical exploration was performed whenever PLF was suspected with the time interval of 2 to 47 days after the trauma. The possible evidence of PLF was found during surgery in 9 cases: a fibrous web around the oval window (n=3), fluid collection in the round window (RW; n=6) and bulging of the RW pseudomembrane (n=1). In every patient, vestibular symptoms disappeared immediately after surgery. The hearing was improved with a mean gain of 27.0±14.9 dB. When the surgical exploration was performed as early as less than 10 days after the trauma, serviceable hearing (≤40 dB) was obtained in 4 out of 7 cases (57.1%). CONCLUSION: Sudden or progressive sensorineural hearing loss accompanied by dizziness following barotrauma should prompt consideration of PLF. Early surgical exploration is recommended to improve hearing and vestibular symptoms.

Effects of Early Surgical Exploration in Suspected Barotraumatic Perilymph Fistulas

OBJECTIVES: Treatment of traumatic perilymph fistula (PLF) remains controversial between surgical repair and conservative therapy. The aim of this study is to analyze the outcomes of early surgical exploration in suspected barotraumatic PLF. METHODS: Nine patients (10 cases) who developed sudden sensorineural hearing loss and dizziness following barotrauma and underwent surgical exploration with the clinical impression of PLF were enrolled. Types of antecedent trauma, operative findings, control of dizziness after surgery, postoperative hearing outcomes, and relations to the time interval between traumatic event and surgery were assessed retrospectively. RESULTS: All patients had sudden or progressive hearing loss and dizziness following trauma. Types of barotrauma were classified by the origin of the trauma: 4 external (car accident, slap injury) and 6 internal traumas (lifting, nasal blowing, straining). Surgical exploration was performed whenever PLF was suspected with the time interval of 2 to 47 days after the trauma. The possible evidence of PLF was found during surgery in 9 cases: a fibrous web around the oval window (n=3), fluid collection in the round window (RW; n=6) and bulging of the RW pseudomembrane (n=1). In every patient, vestibular symptoms disappeared immediately after surgery. The hearing was improved with a mean gain of 27.0+/-14.9 dB. When the surgical exploration was performed as early as less than 10 days after the trauma, serviceable hearing (< or =40 dB) was obtained in 4 out of 7 cases (57.1%). CONCLUSION: Sudden or progressive sensorineural hearing loss accompanied by dizziness following barotrauma should prompt consideration of PLF. Early surgical exploration is recommended to improve hearing and vestibular symptoms.

Headache Associated With Airplane Descent

Headache may develop in flight passengers without underlying pathology even though this type of headache is not included in "The International Classification of Headache Disorders". We report on a case of headache which had developed during airplane landing. A rapid change in the ambient pressure may give rise to headache.