Computer-based thermal imaging of human gingiva: preliminary investigation.

Computer-based thermal imaging techniques were used to compare the rewarming rates of normal and inflamed human gingiva following cooling. A Modified Gingival Index (MGI) score, gingival crevicular fluid (GCF) measurement, and clinical photograph were obtained from a maxillary or mandibular anterior facial region in 20 subjects, aged 25 to 44. Baseline thermograms of the marginal/papillary (M/P) and adjacent attached gingiva (AG) were recorded following an acclimatization period with the patient seated and chin resting on a positioning apparatus. The tissue was then cooled with a gentle stream of air and thermograms were recorded at 10 second intervals for 3 minutes as the tissue rewarmed. Rewarming slopes were calculated based on these thermograms. Correlation coefficients were calculated for MGI with GCF, as well as for both MGI and GCF with AG and M/P rewarming slopes. Mean baseline (SE) temperatures (degrees F) for AG were 75.9 (0.9), 78.0 (0.6), and 80.3 (1.3) for normal, mildly inflamed, and moderately-severely inflamed gingivae, respectively; corresponding mean (SE) temperature differences (degrees F) between AG and M/P were 0.5 (0.2), 0.9 (0.2), and 1.4 (0.3). Intragroup mean M/P temperatures were less than mean AG temperatures, with the mean regional differences increasing with greater severity of inflammation. Rewarming rates also increased as inflammation became more severe, with the rewarming slopes of both the AG and M/P having statistically significant correlations with the MGI and the GCF. The correlation between MGI and GCF was also statistically significant. This study suggests that computer-based thermal imaging techniques can detect both static and dynamic temperature differences between normal gingiva and gingivae with increasing severities of inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between Volpe-Manhold calculus index scores and actual calculus area.

Although the Volpe-Manhold Calculus Index (VMI) is used frequently in clinical trials, it is not clear how representative this index is of the actual tooth surface area covered with calculus. This study correlated the mean VMI and mean calculus area, as measured objectively by using computer-assisted planimetry, in 40 subjects with a wide range of calculus deposition. The resulting statistically significant (p less than 0.05) correlation coefficient of .93 indicates a strong correlation between the VMI and mm2 calculus area, confirming the suitability of this index for use in calculus clinical trials.

Fentanyl, Na-pentobarbital and halothane influence myocardial infarct size.

We investigated the effects of three anesthetics on the size of myocardial infarction and on blood flow distribution within the myocardial wall. Myocardial infarcts were induced in 34 dogs by ligating a coronary artery for 90 minutes, and permitting reflow for 90 minutes. The anesthetics used were fentanyl, Na-pentobarbital, and halothane. Under halothane the mean blood pressure (BP) during coronary artery ligation was 113 +/- 2/82 +/- 2 mm Hg and the heart rate (HR) was 135 +/- 2/min. Under fentanyl, the BP was 143 +/- 3/91 +/- 2 mm Hg and HR 99 +/- 3/min. Under Na-pentobarbital, BP was 141 +/- 2/104 +/- 2 mm Hg and HR 146 +/- 2/min. A higher mean BP combined with a slower HR, as seen under fentanyl, was associated with the smallest infarct (24 +/- 8%). Low BP and higher HR, as seen under halothane, was associated with the largest infarct (51 +/- 5%). Na-pentobarbital, with a higher BP but also a faster HR, resulted in an infarct size of 32 +/- 5%. We conclude that a higher mean BP combined with a slower HR might favor the preservation of a larger mass of vulnerable myocardial tissue in a totally occluded coronary artery.

Placental passage and uterine effects of fentanyl.

Using the chronic maternal-fetal sheep preparation, 27 pregnant ewes were studied to determine the effects of intravenous fentanyl on maternal and fetal physiology, with particular reference to its placental passage, and its effects on uterine blood flow and uterine tone. Three doses of fentanyl were studied--50, 75, and 100 micrograms. Maternal and fetal arterial blood was collected for determination of fentanyl levels. All blood levels, both maternal and fetal, were normalized to the 50-micrograms dose. The maternal normalized blood levels were found to fit a biexponential equation describing a two-compartment open model. The half-life of the maternal elimination phase was 42 +/- 7.0 min with an overall elimination constant (K) of 0.21 min-1. Maternal plasma fentanyl levels decreased very rapidly in the first 10 min after injection, at which time only 9% of the peak value remained. Fentanyl was detectable in fetal blood as early as 1 min and levels peaked at 5 min. Once equilibrium was established between maternal and fetal blood, the maternal levels remained 2.5 times those of the fetal level from 5 min to 60 min after drug injection. Both maternal and fetal drug levels declined in an approximately parallel fashion. No significant deleterious changes were seen in any maternal or fetal cardiovascular or acid-base parameters, and uterine blood flow and uterine tone were also unaffected (P greater than 0.05).

The maternal and fetal cardiovascular effects of epidural morphine in the sheep model.

Interest in the use of epidural narcotics for analgesia has been widespread since the demonstration of opiate receptors in the spinal cord in the mid nineteen-seventies. Recently, several studies have attempted to evaluate the effectiveness of epidural narcotics for the relief of pain in labor and after cesarean section. Using the chronically catheterized maternal-fetal sheep model, we injected 5 mg of preservative-free morphine into the epidural space. No statistically significant changes were observed, neither in maternal or fetal arterial pressure and acid-base status, nor in maternal central venous pressure, systemic and pulmonary vascular resistance, cardiac output, or intrauterine pressure (p greater than 0.05). There was a significant, although small, decrease in maternal heart rate (8%) and uterine blood flow (9%) at 120 minutes (p less than 0.05), and then a return to control values. The maternal levels of morphine peaked at 15 minutes (29 ng/ml) and the fetal levels of morphine peaked at 90 minutes (3 to 4 ng/ml). We conclude that the injection of 5 mg of morphine into the maternal epidural space has no adverse effect on mother or fetus in the sheep model.

Nitroglycerin therapy for phenylephrine-induced hypertension in pregnant ewes.

Obstetrical situations in which endogenous or exogenous vasoactive amines precipitously increase maternal blood pressure and decrease uterine blood flow may be associated with increased maternal morbidity and mortality and with development of fetal acidosis and distress. We examined the effectiveness of nitroglycerin in lowering maternal blood pressure and increasing uterine blood flow during the infusion of the alpha-adrenergic agent phenylephrine. During the phenylephrine infusion maternal blood pressure increased 20%, cardiac output decreased 25%, total peripheral vascular resistance increased 60%, pulmonary arterial pressure increased 40%, uterine blood flow decreased 50%, and fetal arterial pH decreased from 7.37 to 7.30 (p less than 0.05). While maintaining the phenylephrine infusion at a constant rate, the infusion of nitroglycerin rapidly returned maternal systemic pressure and pulmonary arterial pressure to control values, decreased total peripheral resistance to 18% above control, increased cardiac output to 12% below control, increased uterine artery blood flow to 30% below control, and increased the fetal arterial pH from 7.30 to 7.35 (p less than 0.05). It is concluded that maternal hypertension resulting from intense alpha-adrenergic stimulation may be treated rapidly and effectively by the intravenous infusion of nitroglycerin with a partial restoration (20%) of uterine artery blood flow toward control.