Effect of subanaesthetic concentrations of nitrous oxide on the regulation of ventilation in man

The pattern of ventilation was studied in eight healthy male volunteers breathing, in sequence, air and then two subanaesthetic concentrations of nitrous oxide (20% and 40%). The effect of these gas mixtures on the response to an added inspiratory resistance (3.88 kPa litre-1s-1) was examined. During unrestricted breathing of 40% nitrous oxide, there was a significant decrease (P less than 0.05) in inspiratory time (TI), a concomitant increase in the rate of ventilation and a significant decrease (P less than 0.05) in the end-tidal carbon dioxide tension (PE'CO2) compared with air breathing. For the first breath on load while breathing 40% nitrous oxide, there were significant decreases (P less than 0.05) in the responses for TI and tidal volume (VT) compared with the responses when breathing air. TI, VT, minute volume and PE'CO2 were similar for each gas mixture during steady state breathing against resistance. The increase in PE'CO2 when breathing 40% nitrous oxide against the resistance represented a significant (P less than 0.01) difference in response to the load compared with that breathing air. There was no significant change in these variables when breathing 20% nitrous oxide.

Retrenchment: layoff procedures in a nonprofit organization

One of the most unsettling experiences that human resources and other managers must face is a large-scale employee layoff. Authors Robert Fuller, national director of personnel, Cassandra Jordan, assistant director of personnel, and Robert Anderson, employment and training manager--all at the Legal Services Corporation--show how careful management planning, extensive staff involvement, and well-planned counseling and outplacement services helped employees of Legal Services Corporation wheather such a layoff. As the first step, the planning committee (personnel director, equal employment opportunity director, and general counsel) recommended that the corporation conduct staff education about layoffs for all employees, that a representative employee task force be established to develop specific details of the layoff plan, and that the corporation hire an experienced person to help staff members implement the plan. Members of the task force, who were elected by staff members (except for one additional member who was selected to ensure proper representation of minority groups and women), made specific recommendations on the way to determine seniority and bumping rights. The task force also dealt with such issues as method of notification, an appeals procedure, reemployment rights, the counseling and outplacement services. The task force also considered the issue of "willingness to leave".

Electromyographic gait analysis before and after operative treatment for hemiplegic equinus and equinovarus deformity

Gait electromyograms were obtained before and after tendon transfer, lengthening, or release in twenty-seven hemiplegic patients with equinus or equinovarus deformities. Abnormal patterns of muscle activity almost always were present preoperatively in the gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, flexor digitorum longus, peroneus brevis, and tibialis anterior muscles in these patients. The surgical procedures to correct the foot deformities altered the gross patterns of activity of most of the muscles operated on by very little. Of particular importance to the surgeon was the finding that the pattern of activity of the muscles whose tendon was transferred, lengthened, or released was not altered after operation. This finding makes the preoperative gait electromyogram a useful means of determining the appropriate surgical plan, since it is an indication of the type of muscle activity to expect postoperatively.

Specific conductance using forced airflow oscillation in mechanically ventilated human subjects

A method is described to measure specific airway conductance in mechanically ventilated patients. Airflow resistance (R) was measured continuously using the forced airflow oscillation method and plotted against volume during slow deflation of the lungs. The previously reported hyperbolic configuration of the resistance-volume curve was confirmed, but a nonlinear conductance-volume relationship was found that could be explained by a constant resistance (A) in series with the volume-dependent resistance of the lower airways. A computer-aided analysis of the resistance-volume curve determined the parameters of the hyperbola that best fitted the data and from this the volume-dependent conductance, Glaw = 1/(R - A), was calculated. This method consistently provided a very good fit to the data and resulted in a linear lower airway conductance-volume relationship in anesthetized and in awake subjects. The slope of this linear relationship (Glaw) was therefore independent of volume, and specific lower airway conductance was used as an index of bronchomotor tone. In awake subjects given bronchoconstrictor and bronchodilator aerosols, good correlation was shown between changes in specific conductance measured by this technique and by the standard plethysmographic method.

Rapid improvement in abnormal pulmonary epithelial permeability after stopping cigarettes

A new, non-invasive method of measuring pulmonary epithelial damage in man was compared with traditional tests of small-airway function. Pulmonary epithelial permeability was expressed as the half-time clearance from the lung into blood of (99m)Tc-diethylene triaminepenta-acetic acid ((99m)Tc-DTPA) deposited predominantly in the alveoli from an inhaled aerosol.Recovery from abnormal pulmonary permeability was recorded after stopping smoking for 21 days in a group of young symptomless cigarette smokers. Before stopping smoking there was a significant correlation between half-time lung clearance of (99m)Tc-DTPA and carboxyhaemoglobin concentration (r=0.69; p <0.05). There was no correlation between carboxyhaemoglobin value and closing volume, the only other abnormal test of airway function. Twenty-four hours after stopping smoking the mean half-time lung clearance of (99m)Tc-DTPA had increased significantly (p <0.001) from a baseline of 15.8 min (SEM 1.3 min) to 25.5 min (SEM 2.5 min). The mean half-time clearance continued to increase to a maximum of 35.5 min (SEM 3.1 min) at seven days, but was significantly less than the reported half-time clearance for non-smokers (59 min, SEM

Alcohol induced discoordination is not reversed by naloxone

It has previously been reported that prior administration of naloxone may prevent the decrement in performance produced by alcohol. To be clinical value, however, naloxone must be shown to reverse rather than prevent this decrement. This study examined the effect of naloxone given after consumption of alcohol. A double blind balanced crossover protocol was used to examine the effect of either 1.2 mg or 10 mg naloxone on the sensory-motor impairment produced by blood alcohol concentrations maintained between 75 and 85 mg/100 ml. This alcohol concentration significantly impaired two measures of sensory-motor performance, but there was no evidence that either dose of naloxone could reverse this decrement. We tested our subjects for a chlorpropamide alcohol flush but none gave a positive response. These results indicate that naloxone (1.2 mg or 10 mg) does not reverse the sensory-motor impairment produced by alcohol intoxication in subjects who do not exhibit a chlorpropamide alcohol flush. Nearly all the subjects exhibited somnolence after receiving alcohol and naloxone (1.2 mg or 10 mg) but not after receiving alcohol and saline.

Respiratory depression following diazepam: reversal with high-dose naloxone

The authors compared the effects of naloxone and saline solution on the respiratory changes following diazepam in a double-blind crossover trial in six subjects. Following baseline measurements of respiration, each subject was given diazepam, 15 mg, intravenously. Sixty and ninety-five minutes later each subject received either two doses of naloxone, 15 mg, intravenously, or two doses of the equivalent volume of saline solution. Forty-five minutes after diazepam administration the slopes of the curves of the ventilatory responses to rebreathing carbon dioxide (VE/PETCO2) were depressed to 53 per cent of control (P < 0.05). Following the two doses of naloxone, the slopes of VE/PETCO2 recovered, until, 120 minutes after the second dose of naloxone, slopes had returned to control values. After saline solution, however, slopes remained depressed at 68 per cent of control (P < 0.05). A similar recovery following naloxone was observed in the PETCO2 intercept of the VE/PETCO2 response curve and in the slope of the mouth-occlusion-pressure response curve to rebreathing carbon dioxide. End-tidal carbon dioxide during quiet breathing and during inspiratory resistive-loaded breathing (80 cm H2O/l/s) showed small increases after diazepam, which were not significantly reduced by naloxone. The results of this study show that diazepam produces respiratory depression, and that this may be relieved by large doses of naloxone.

Respiratory effects of analgesia after cholecystectomy: comparison of continuous and intermittent papaveretum

Two methods of administering papaveretum for relieving postoperative pain were compared in two groups of patients who had undergone cholecystectomy. In one group a loading dose of papaveretum was administered by continuous intravenous infusion (1 mg/min) until the patient could breathe deeply without undue pain. Eight times this loading dose was given as a continuous intravenous infusion over the subsequent 48 hours. This regimen was compared with a conventional intermittent intramuscular dose (0.25 mg/kg at four hourly intervals as necessary) in a second group of patients. The intravenous regimen relieved pain better than the intramuscular regimen, which may have reflected the larger dose of papaveretum given to the intravenous group, but it was accompanied by a greater degree of respiratory depression and potentially life-threatening changes in respiratory pattern. These findings suggest that the fear which often accounts for inadequate postoperative pain relief-that larger dose of analgesics will cause respiratory complications-is well founded.