Estimation of the probability of disturbed breathing during sleep before a sleep study.

We have investigated the ability of a statistical model developed from clinical data and questionnaire responses to predict disturbance of breathing during sleep. Data from 100 consecutive patients referred for sleep study for suspected sleep apnea were used to develop the model using logistic regression analysis. For each subject, the model predicted the probability of having an apnea-hypopnea index (AHI) greater than 15; this probability was compared with the AHI measured from sleep study. A probability cutoff point (= 0.15) was decided on that minimized the number of subjects with false-negative predictions. Four terms--apneas observed by bed partner, hypertension, body mass index, and age--were found to contribute significantly to the model with observed apneas being by far the most predictive term of the four (adjusted odds ratio 19.7). When the model was tested to estimate the probability of an AHI greater than 15 for 105 patients from a second group of consecutive patients referred for sleep study, the model correctly classified 33 of 36 patients with a measured AHI greater than 15 (sensitivity = 92%) and 35 of 69 patients with a measured AHI less than or equal to 15(specificity = 51%). This study shows that analysis of clinical features of patients presenting with suspected sleep apnea may reduce the need for sleep studies by about one-third yet still lead to the identification of the great majority of patients with abnormal breathing during sleep.

Generalized anxiety disorder: some biochemical aspects.

Fifty-one patients who met DSM-III criteria for generalized anxiety disorder, and who were recruited to participate in a drug outcome study, filled out a variety of rating scales and had blood samples drawn for plasma norepinephrine, epinephrine, and free 3-methoxy-4-hydroxyphenylglycol (MHPG) after a 20-min rest period. This group was compared to 15 normal controls who also had their blood drawn after a 20-min rest period. While the two groups were initially found to have significantly different levels of plasma free MHPG through the use of t tests, this finding was not confirmed by subsequent discriminant analysis.

Alprazolam, propranolol, and placebo in the treatment of panic disorder and agoraphobia with panic attacks.

Fifty-five patients completed a 5-week double-blind study comparing alprazolam, propranolol, and placebo in the treatment of panic disorder and agoraphobia with panic attacks. There was no concomitant behavioral treatment. Patient and therapist rating scales included Sheehan's Panic and Anxiety Attack Scales, the Marks-Sheehan Phobia Scale, the Hamilton Anxiety Scale, the Hamilton Depression Scale, and the Side Effects Checklist. The results generally support the efficacy of alprazolam, but not propranolol, in the treatment of panic disorder and agoraphobia with panic attacks. The significance of the results are discussed, as well as a number of the unique aspects of our procedures and patient population.

Uvulopalatopharyngoplasty as a treatment for snoring.

Uvulopalatopharyngoplaty was performed in 18 consecutive patients (15 men and three women; mean +/- standard deviation [SD] age, 46.3 +/- 7.5 years) who presented for the treatment of heavy habitual snoring. No attempt was made to select patients who were ideal anatomically for palatal modification. The loudness of snoring was measured during sleep by integrating the output of a calibrated microphone. An assessment before operation showed that nine patients had obstructive sleep apnoea; four patients had an apnoea index of greater than or equal to 25 apnoeas per hour. The patients were overweight and consumed, on average, 38 g of alcohol per day, but these variables did not change after the operation. The postoperative assessment was performed 138 +/- 44 days after uvulopalatopharyngoplasty. Fourteen patients showed a reduction in the loudness of their snoring, although snoring was abolished in one patient only (average snoring loudness in arbitrary units/min of sleep, 2.8 +/- 2.1 before operation compared with 1.4 +/- 1.5 units/min of sleep after the operation; P less than 0.05. The loudest snore in arbitrary units measured 7.1 +/- 3.3 units compared with 4.8 +/- 3.3 units, respectively; P less than 0.05). The percentage of the sleep time that was spent at an arterial oxygen saturation of less than 90% was reduced after uvulopalatopharyngoplasty (28% +/- 32% of total sleep time compared with 17% +/- 24% of total sleep time, respectively; P less than 0.05). There was no change in the apnoea index. The diastolic blood pressure was lower at the postoperative assessment (94 +/- 11 mmHg compared with 87 +/- 8 mmHg; P less than 0.05); six of 10 subjects whose diastolic blood pressures were greater than or equal to 95 mmHg before the operation had a diastolic blood pressure of less than 95 mmHg after uvulopalatopharyngoplasty (P less than 0.02). Computed tomographic scans showed an increase in the upper airway cross-sectional area at 3 cm and 4 cm above the hyoid bone after uvulopalatopharyngoplasty (P less than 0.05). We conclude that uvulopalatopharyngoplasty is an effective treatment for habitual, heavy snoring in many patients, but it is not the treatment of choice for patients with clinically-significant obstructive sleep apnoea.

Nortriptyline in the treatment of panic disorder and agoraphobia with panic attacks.

Thirty-four consecutive patients with panic disorder or agoraphobia with panic attacks were treated with nortriptyline at the LAC-USC Medical Center's Anxiety Disorders Clinic. Fourteen (67%) of the 21 completers totally lost their panic attacks, five (24%) showed partial improvement, and two (10%) showed no improvement. The relationship of treatment outcome to pretreatment and posttreatment measures of depression is discussed, in addition to the potential role of nortriptyline in treating panic attacks in clinical practice.

Isolation and purification of a Thy-1-like glycoprotein from sheep brain and its distribution in ovine tissues.

Standard methods for the purification of Thy-1 were applied to sheep brain to purify a sheep brain membrane glycoprotein (SBMG). On 12 per cent sodium dodecylsulphate polyacrylamide gels this glycoprotein was shown to be a doublet with apparent molecular weights 24,000 and 25,000. By a number of physicochemical criteria SBMG was shown to have properties similar to those previously reported for Thy-1 isolated from other species. Immunological investigations, however, revealed that SBMG did not react with rabbit anti-rat Thy-1 and rabbit anti-SBMG did not recognise rat or chicken brain. By fluorescent antibody techniques the tissue distribution of SBMG appeared to be similar to that of Thy-1 in other species. A small population of peripheral blood and intestinal lymph lymphocytes were stained with anti-SBMG. These results suggest that sheep have an immunologically distinct Thy-1 homologue.

Temperature monitoring during general anaesthesia.

A study of core temperature monitoring during general anesthesia indicates that this can be introduced as a routine procedure in order to reduce mortality from malignant hyperpyrexia. The temperature profiles of 2410 patients are presented. Both mean rectal and mean oesophageal temperatures decreased during general anaesthesia. The mean oesophageal temperatures were on average 0.6 degrees C less than the mean rectal temperatures during the first hour of anaesthesia. An increase in core temperature occurred in nearly 20% of patients. This appeared to be related to an initially low body temperature. Core temperatures during general anesthesia were significantly greater in patients who received the combination of suxamethonium and halothane than in patients receiving other drugs. This observation is of theoretical interest and suggests that the increase of temperature in malignant hyperpyrexia may be an exaggeration of a normal response to these agents.

Site of the muscle cell abnormality in swine susceptible to malignant hyperpyrexia.

In vitro studies, using agents which act specifically on different parts of the muscle contractile mechanism, suggest that the abnormality in malignant hyperpyrexia susceptible (MHS) swine muscle lies distal to the postjunctional membrane, and that it is not a result of widespread acetylcholine receptors throughout the muscle membrane. Two possible sites are involved, one being the sarcolemma and the T-system, the other the excitation-contraction coupling mechanism and the sarcoplasmic reticulum.

Identification of susceptibility to malignant hyperpyrexia in swine.

In vitro muscle contracture responses in swine susceptible to malignant hyperpyrexia (MH) were similar to those found in muscle from humans susceptible to this anaesthetic complication, confirming the suitability of the pig as an animal model for studying MH. The results suggest that there are different degrees of susceptibility to MH. Whichever drug was used, there was some overlap in the contracture responses between susceptible animals and controls, suggesting that the most accurate way of identifying susceptibility to MH is to use a variety of chemical agents, the best of which seem to be halothane, caffeine, suxamethonium and potassium chloride. Thymol, which is used as a preservative in commercial preparations of halothane, potentiates halothane contractures, but it is not known if this is significant clinically.