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Continuous transcutaneous oxygen measurement: Reproducibility and trace analysis in healthy adults
646
CURRENT LITERATURE
Oral-Antral Fistulae-A Study of Clinical, Radiological and Treatment Aspects. de S. Amaratunga NA. Br J Oral Maxillofac Surg 24:433, 1986 A series of 86 patients with oral-antral fistulae were analyzed regarding age, sex, site, presenting features, radiographic appearance, and duration. Diagnostic criteria and a brief synopsis of treatment for each patient are presented. Oral-antral fistulae occurred more often in males (66%) than in females (34%), were most common in the fourth (41%) and fifth (23%) decades, and are usually related to the uppr first molar (49%). The maxillary second molar and the maxillary second premolar were the second and third most common sites. Symptoms at time of diagnosis were pain in the maxilla and suppuration. The time lapse between occurrence and discovery of the oral-antral fistula were greater than one year after the extraction in 51% of the cases, and 33% were diagnosed after six months. Radiographic evidence indicated that 49% had polyps with mucosal thickening, and a fluid level was found in 20% of the cases. Results of surgical repair indicated there was no significant difference between the buccal flap and the palatal flap techniques.ROBERT B. YOUNG
Reprint requests to Dr. Amaratunga: Division of Oral Surgery, Dental School, Peradeniya, Sri Lanka. Magnetic Resonance Imaging of the Salivary Glands: A Comparison with Computed Tomographic Scanning. Rice DH, Becker T. Arch Otolaryngol 113:78, 1987 Of a variety of diagnostic imaging techniques currently available for investigation of parotid gland lesions, computed tomography (CT) has been the most valuable. Over the past several years, a comparison was made between CT and magnetic resonance imaging of parotid gland lesions from the Departments of Otolaryngology and Radiology, University of Southern California School of Medicine at Los Angeles. Theoretical and actual advantages and disadvantages of both techniques are described. Several case reports compare the diagnostic aspects of both techniques. In general terms, magnetic resonance tomography shows the mass in greater contrast to the surrounding tissue but less adjacent tissue detail than does CT. It was found that for now CT may be more accurate in detecting small masses but less so in other instances. It was felt that continued improvement in magnetic resonance imaging will eventually eliminate the need for CT.-HAROLD
MACHESKY
oxygen, while the experimental group inspired a mixture of 50% nitrous oxide and 50% oxygen. Blood gases are analyzed at time zero, five, 10, and 15 minutes during inspiration of a mixture and 30 seconds, 65 seconds, 2.5, 5, and 10 minutes following the return to breathing room air. The subjects demonstrated no evidence of arterial hypoxemia at any time during the monitoring period. No significant differences in Pa02, were noted in the control group while breathing either mixture. The authors conclude that diffusion hypoxia is not seen in normal subjects following self-administration of a mixture of 50% nitrous oxide and oxygen, but note these results may be valid only for those patients without respiratory or cardiovascular compromise.-JAMES L. HORNER Reprint requests to Dr. Stewart: Center for Emergency Medicine, 190 Lothrop Street, Pittsburgh, PA 15213.
Continuous Transcutaneous Oxygen Measurement: Reproducibility and Trace Analysis in Healthy Adults. Swift AC, Downham DY. Acta Anesthesiol Stand 30:458, 1986 Transcutaneous blood gas monitoring is a useful adjunct in the assessment of tissue perfusion, but due to variations in the thickness and vascularity of adult skin, the interpretation of oxygen diffusion values is difficult. A reliable means of assessment was sought by the authors, who compiled 114 mass spectrometer tracings generated from 46 adult subjects. The subjects were divided into four groups based upon the same or a different sampling site, and samples obtained on the same or a different day. The tracings rose initially and fluctuated about a plateau level. Two models of statistical analysis are presented to reach a way of computing an estimate of the transcutaneous oxygen plateau level. The “time series model” assumes each sample to be linearly related, whereas the “growth model” describes the trace in terms of its rate of approach to the plateau level. As applied to the data, the authors found greater correlation coefficients in the estimates of the plateau levels computed from the group sampled at the same site on the same day, while the lowest correlates were found in the group sampled at different sites on different days. The estimates derived from the “time series model” were more accurate than those of the “growth model” although more sophisticated statistical methods and computational expertise are required. The authors claim transcutaneous measurement of oxygen tension by a mass spectrometer and the use of two statistical models yields estimates of plateau levels that are reproducible.JAMES L. HORNER
Reprint requests to Dr. Rice: Department of OtolaryngologyHead and Neck Suraerv. Universitv of Southern California School of Medicine, gox-j95, 1200 N&h State Street, Los Angeles, CA 90033. Arterial
Blood Gases
Before,
During,
and After
Nitrous
Oxide: Oxygen Administration. Stewart RD, Gorayeb MJ, Pelton GH. Ann Emerg Med 15: 1177, 1986 Concerns over the potential of diffusion hypoxia following the administration of nitrous oxide and oxygen have existed for nearly 30 years. Investigation of postinhalation diffusion hypoxia in this study utilizes the arterial blood gases of 20 healthy adult males before, during, and after the administration of a mixture delivered through a demand valve apparatus. Ten subjects were administered a control mixture of 50% nitrogen and 50%
Reprint requests to Dr. Swift: Department of Otolaryngology, University of Liverpool, Liverpool L69 3BX, England.
Composite Photo-Radiography. Photography 21:20, 1986
Acharia KM. Functional
In an effort to assist physicians in correlating radiographic studies of the “flesh and blood” patient that sits before them, the author has devised the photo-composite radiograph. The composite provides a method of correlating relative positions of bones and soft tissues in one image, with both interior (radiographic) and exterior (photographic) views. A superimposition of a lateral cephalometric radiograph and corresponding profile photo is provided as an example. The author points out the value of that particular study in the diagnosis and
CURRENT LITERATURE
Oral-Antral Fistulae-A Study of Clinical, Radiological and Treatment Aspects. de S. Amaratunga NA. Br J Oral Maxillofac Surg 24:433, 1986 A series of 86 patients with oral-antral fistulae were analyzed regarding age, sex, site, presenting features, radiographic appearance, and duration. Diagnostic criteria and a brief synopsis of treatment for each patient are presented. Oral-antral fistulae occurred more often in males (66%) than in females (34%), were most common in the fourth (41%) and fifth (23%) decades, and are usually related to the uppr first molar (49%). The maxillary second molar and the maxillary second premolar were the second and third most common sites. Symptoms at time of diagnosis were pain in the maxilla and suppuration. The time lapse between occurrence and discovery of the oral-antral fistula were greater than one year after the extraction in 51% of the cases, and 33% were diagnosed after six months. Radiographic evidence indicated that 49% had polyps with mucosal thickening, and a fluid level was found in 20% of the cases. Results of surgical repair indicated there was no significant difference between the buccal flap and the palatal flap techniques.ROBERT B. YOUNG
Reprint requests to Dr. Amaratunga: Division of Oral Surgery, Dental School, Peradeniya, Sri Lanka. Magnetic Resonance Imaging of the Salivary Glands: A Comparison with Computed Tomographic Scanning. Rice DH, Becker T. Arch Otolaryngol 113:78, 1987 Of a variety of diagnostic imaging techniques currently available for investigation of parotid gland lesions, computed tomography (CT) has been the most valuable. Over the past several years, a comparison was made between CT and magnetic resonance imaging of parotid gland lesions from the Departments of Otolaryngology and Radiology, University of Southern California School of Medicine at Los Angeles. Theoretical and actual advantages and disadvantages of both techniques are described. Several case reports compare the diagnostic aspects of both techniques. In general terms, magnetic resonance tomography shows the mass in greater contrast to the surrounding tissue but less adjacent tissue detail than does CT. It was found that for now CT may be more accurate in detecting small masses but less so in other instances. It was felt that continued improvement in magnetic resonance imaging will eventually eliminate the need for CT.-HAROLD
MACHESKY
oxygen, while the experimental group inspired a mixture of 50% nitrous oxide and 50% oxygen. Blood gases are analyzed at time zero, five, 10, and 15 minutes during inspiration of a mixture and 30 seconds, 65 seconds, 2.5, 5, and 10 minutes following the return to breathing room air. The subjects demonstrated no evidence of arterial hypoxemia at any time during the monitoring period. No significant differences in Pa02, were noted in the control group while breathing either mixture. The authors conclude that diffusion hypoxia is not seen in normal subjects following self-administration of a mixture of 50% nitrous oxide and oxygen, but note these results may be valid only for those patients without respiratory or cardiovascular compromise.-JAMES L. HORNER Reprint requests to Dr. Stewart: Center for Emergency Medicine, 190 Lothrop Street, Pittsburgh, PA 15213.
Continuous Transcutaneous Oxygen Measurement: Reproducibility and Trace Analysis in Healthy Adults. Swift AC, Downham DY. Acta Anesthesiol Stand 30:458, 1986 Transcutaneous blood gas monitoring is a useful adjunct in the assessment of tissue perfusion, but due to variations in the thickness and vascularity of adult skin, the interpretation of oxygen diffusion values is difficult. A reliable means of assessment was sought by the authors, who compiled 114 mass spectrometer tracings generated from 46 adult subjects. The subjects were divided into four groups based upon the same or a different sampling site, and samples obtained on the same or a different day. The tracings rose initially and fluctuated about a plateau level. Two models of statistical analysis are presented to reach a way of computing an estimate of the transcutaneous oxygen plateau level. The “time series model” assumes each sample to be linearly related, whereas the “growth model” describes the trace in terms of its rate of approach to the plateau level. As applied to the data, the authors found greater correlation coefficients in the estimates of the plateau levels computed from the group sampled at the same site on the same day, while the lowest correlates were found in the group sampled at different sites on different days. The estimates derived from the “time series model” were more accurate than those of the “growth model” although more sophisticated statistical methods and computational expertise are required. The authors claim transcutaneous measurement of oxygen tension by a mass spectrometer and the use of two statistical models yields estimates of plateau levels that are reproducible.JAMES L. HORNER
Reprint requests to Dr. Rice: Department of OtolaryngologyHead and Neck Suraerv. Universitv of Southern California School of Medicine, gox-j95, 1200 N&h State Street, Los Angeles, CA 90033. Arterial
Blood Gases
Before,
During,
and After
Nitrous
Oxide: Oxygen Administration. Stewart RD, Gorayeb MJ, Pelton GH. Ann Emerg Med 15: 1177, 1986 Concerns over the potential of diffusion hypoxia following the administration of nitrous oxide and oxygen have existed for nearly 30 years. Investigation of postinhalation diffusion hypoxia in this study utilizes the arterial blood gases of 20 healthy adult males before, during, and after the administration of a mixture delivered through a demand valve apparatus. Ten subjects were administered a control mixture of 50% nitrogen and 50%
Reprint requests to Dr. Swift: Department of Otolaryngology, University of Liverpool, Liverpool L69 3BX, England.
Composite Photo-Radiography. Photography 21:20, 1986
Acharia KM. Functional
In an effort to assist physicians in correlating radiographic studies of the “flesh and blood” patient that sits before them, the author has devised the photo-composite radiograph. The composite provides a method of correlating relative positions of bones and soft tissues in one image, with both interior (radiographic) and exterior (photographic) views. A superimposition of a lateral cephalometric radiograph and corresponding profile photo is provided as an example. The author points out the value of that particular study in the diagnosis and