Acute exacerbations of chronic obstructive pulmonary disease and mechanical ventilation: a reevaluation.

OBJECTIVE: To review the intensive care unit (ICU) experience of patients admitted with acute exacerbations of chronic obstructive pulmonary disease. DESIGN: Retrospective case series. SETTING: University teaching hospital. PATIENTS: We reviewed the records of 100 consecutive ICU admissions of patients with acute exacerbations of chronic obstructive pulmonary disease over a period of 4.25 yrs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were characterized using a computerized prospective database and case note review. Multivariate analysis identified variables predicting ICU and hospital length of stay. The Cox proportional hazards model was used to analyze survival after hospital discharge. Seventy-five patients (24 female and 51 male, mean age 68.5 +/- 7 [SD] yrs) with 100 ICU admissions were identified. Premorbid airway obstruction was severe, with forced expiratory volume in 1 sec (FEV1)/forced vital capacity (FVC) of 0.7 +/- 0.34 L and FEV1/FVC of 39 +/- 16%. Thirty-two percent received home-administered oxygen and 42% were housebound. The pre-ICU admission PaCO2 was 86 +/- 28 torr (11.5 +/- 3.7 kPa), with a pH of 7.24 +/- 0.11 and a PaO2/FIO2 of 190 +/- 66. ICU admission Acute Physiology and Chronic Health Evaluation II score was 18 +/- 5. Forty-three patients were mechanically ventilated for a median of 4 days (range 0.08 to 30). Tracheostomy, in seven patients, was maintained for 21 +/- 7 days. Ventilation time and tracheostomy frequency predicted length of ICU stay (median 3 days; range 1 to 40) and hospital stay (17 days; 4 to 97), respectively. ICU and hospital case-fatality rates were 1% and 11%. Out-of-hospital (24-month) probability of survival was predicted by plasma albumin concentration at the time of ICU admission; this probability of survival was .64 at an albumin concentration of 38 g/L. CONCLUSIONS: ICU admission of severely ill chronic obstructive pulmonary disease patients results in acceptable outcomes. Survival of < or =2 yrs is not affected by mechanical ventilation or tracheostomy requirement.

N-acetyl-L-cysteine depresses cardiac performance in patients with septic shock.

OBJECTIVE: To investigate the effects of adjunctive therapy with parenteral N-acetyl-L-cysteine in patients with newly diagnosed septic shock. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: Multidisciplinary intensive care unit at a university teaching hospital. PATIENTS: Twenty patients (N-acetyl-L-cysteine group [n = 10], placebo group [n = 10]), 15 male and five female, of mean age 64 +/- 15 (SD) yrs and Acute Physiology and Chronic health Evaluation (APACHE) II score 33 +/- 6, with septic shock within 24 hrs of diagnosis. INTERVENTIONS: After a 2-hr stabilization period (time-zero minus 2 hrs to time-zero), patients received either N-acetyl-L-cysteine in 5% dextrose (150 mg/kg in 100 mL over 15 mins, followed by 50 mg/kg in 250 mL over 4 hrs, and then 100 mg/kg/24 hrs in 500 mL for 44 hrs; N-acetyl-L-cysteine group) or the equivalent volume of 5% dextrose (placebo group). MEASUREMENTS AND MAIN RESULTS: Hemodynamic and oxygen transport indices were measured at time-zero minus 2 hrs and time-zero, and at multiple time points thereafter until completion of the trial infusion (time-zero plus 48 hrs). A daily Organ Failure Score was recorded for 14 days. Treatment group demographics and hemodynamic variables did not differ significantly between the two groups at time-zero. Mean (SD), pooled mean arterial pressure (MAP), and cardiac index were 75 +/- 15 mm Hg and 3.9 +/- 1.2 L/min/m2, respectively. Over the next 48 hrs, in the N-acetyl-L-cysteine group, there was a progressive decrease, relative to both time-zero and the placebo group, in MAP, cardiac index, and left ventricular stroke work index (p < .01, repeated-measures analysis of variance). Percentage reductions in these values relative to the placebo group at 48 hrs were 23%, 18%, and 43%, respectively Oxygen transport indices, arterial blood gas analyses, Pao2/Fio2 ratio, and shunt did not differ over time between the groups. There was no difference in either daily Organ Failure Score over time (p > .01, repeated-measures analysis of variance) or hospital mortality rate (90% N-acetyl-L-cysteine group, 50% placebo group) (p > .1, logistic regression) between the two groups. CONCLUSION: Adjunctive therapy with N-acetyl-L-cysteine in newly diagnosed septic shock was associated with a depression in cardiovascular performance, as indicated by progressive reductions in cardiac index, left ventricular stroke work index, and MAP.

Microvascular luminal volume changes in aged mouse periodontal ligament.

Data for the microvascular bed in the aged periodontal ligament have not been established. This investigation tested the hypothesis that the luminal microvascular volume decreased in the aged ligament. Mice 35 days old and one year old were vascular-perfused and the mandibular first molar periodontal ligament processed for electron microscopy. Tissue quadrats from each circumferential third ligament region were recorded at 150-microns intervals from the alveolar crest to the apex for randomized sampling of blood vessel lumina. The data were analyzed with a generalized linear model at the p < 0.01 level for the interaction of the aging effect with differences across regions. Stereological parameters were established for vessel lumen volume, and for surface and length densities. Mean ligament width decreased from 119.9 +/- 16.94 (micron +/- SE) in young mice to 60.0 +/- 10.58 (micron +/- SE) in aged mice. The luminal volume of 8.63 +/- 1.37 (% +/- SE) in young ligament increased to 9.83 +/- 2.14 (% +/- SE) in aged ligament. Collecting venules and the combined group of arterio-venous anastomoses with terminal arterioles showed a two-fold increase in luminal volume density (p < 0.01). In aged ligament, regional shifts affected the microvascular bed distribution, but these changes were not consistent across regions, or with depth. The average cross-sectional tissue area served per capillary decreased from 2117 microns 2 to 1451 microns 2 for young and old. Average ligament thickness served per capillary dropped from 52.5 microns to 27.5 microns. These reductions in average diffusion distances indicated a change in the quality of the diffusion barrier with age.

Intra-operative patient-controlled sedation and patient attitude to control. A crossover comparison of patient preference for patient-controlled propofol and propofol by continuous infusion.

Intra-operative patient controlled sedation with propofol (bolus dose 18 mg over 5.4 s; lockout period 1 min) has been compared to continuous propofol infusion (3.6 mg.kg-1.h-1) in a randomised crossover study of 38 ASA 1 or 2 day surgery patients undergoing two-stage bilateral extraction of third molar teeth under local anaesthesia (76 procedures). Mean (SD) propofol used (mg.kg-1) was less with patient-controlled sedation (2.39 (1.28) than with the infusion (2.58 (0.84)) but the difference was not statistically significant. There were only minor differences between the methods in postoperative recovery of cognitive function and no differences for patient cooperation and surgeon's satisfaction with sedation. Patient-controlled sedation was preferred by 19 patients, continuous infusion by 10, with nine indifferent. Preferences, expressed as mild, moderate or strong, were significantly stronger for patient-controlled sedation (p < 0.05). Sedation was no deeper than eyelid closure with response to command in all 76 procedures. This level was reached in all 38 infusion cases but in only 26 cases with patient-controlled sedation, where 12 patients remained less sedated (p < 0.01). Patient-controlled sedation with propofol provided safe sedation and was strongly preferred over the infusion by a large proportion of patients.

Predictions of restoration deterioration.

This study evaluated the application of a mixture model involving a Weibull distribution function to predict the median times for restorations of three dental restorative materials to achieve unsatisfactory rating scores for six clinical factors. The accuracy of the method was assessed graphically against the known actuarial long-term deterioration observations of 1813 amalgam, 1774 anterior resin composite and 474 glass polyalkenoate (ionomer) cement restorations, assessed over periods of up to 20, 18 and 14 years, respectively. Of the six clinical factors investigated (which included marginal fracture), only four had sufficient long-term unsatisfactory rating score data to enable their median times to be predicted. These predicted times were: for amalgam restorations, surface roughness 32.5 years and surface tarnishing 16.0 years; for resin composites, marginal staining 25.4 years and colour mismatch 14.2 years; and for glass polyalkenoate (ionomer) cements, marginal staining 17.6 years and colour mismatch 3.6 years. The known and predictive unsatisfactory rating score results were generally in close agreement. However, it was not possible to predict median times for unsatisfactory rating scores associated with very slowly deteriorating restoration factors. The actual replacement rates of the amalgam restorations were too low to obtain their median survival time. However, for the faster failing resin composites this time was 7.9 +/- 0.5 years, and for the glass polyalkenoate (ionomer) cements 2.2 +/- 0.2 years. The relationship of restoration deterioration to restoration replacement and dental health requires further analysis.

Double-blind comparison of patient recovery after induction with propofol or thiopentone for day-case relaxant general anaesthesia.

Postoperative recovery after induction with either propofol or thiopentone has been compared in forty ASA I unpremedicated day surgery patients undergoing surgical extraction of third molar teeth under relaxant general anaesthesia. Mean recovery times in the propofol group, required for patients to sit out of bed (44.8 minutes; SD 18.6) and meet discharge criteria (113.1 minutes; SD 34.5) were significantly (P less than 0.05) shorter than those in the thiopentone group (59.7 minutes; SD 21.4 and 133.5 minutes; SD 34.5). Fewer patients in the propofol group were treated in the recovery room for nausea and vomiting and the incidence of mild nausea not requiring treatment was less in the propofol group, but these differences were not statistically significant. Postoperative mental performance, measured by the FAST index, a new test of mental speed, was reduced on average by 1.7% of preoperative levels, during the recovery period tested, with no significant difference between the groups.

Survival predictions of amalgam restorations.

The purpose of this study was to evaluate survival predictions made for four different amalgam alloy restorations, using a mixture model involving the standard Weibull function. The amalgam alloys were placed by students and staff in patients attending a dental hospital, and 1680 restorations were examined over periods of up to 18 years. Based on maximum likelihood estimations of the parameters of the mixture model distribution, predictive survival distributions were generated and found to match closely the actuarial survival estimates established from the same data. The 13-year restoration survivals of one low-copper alloy could be predicted accurately from the 6-year survival results. However, another low-copper alloy and two high-copper alloys with much lower restoration failure rates required 18 years of data for accurate long-term survival predictions.

Survival predictions of four types of dental restorative materials.

The present study assessed the survival predictions made for four different types of dental restorative materials, using a mixture model involving the standard Weibull distribution function. A large number of amalgam, anterior resin, glass polyalkenoate (ionomer) cement, and pit and fissure sealant restorations were examined over varying periods of up to 18 years. The materials had been placed by numerous staff and students at a teaching hospital. Based on maximum likelihood estimations of the parameters of the mixture model distribution, survival curves were generated and found to agree closely with the actuarial survival curves estimated from the same data. As the years of data used to fit the mixture model curves decreased, then the fitted curves started to exhibit obvious divergences from the actuarial curves at 12-13 years for amalgams, 3-4 years for anterior resins and sealants, and 1-2 years for glass polyalkenoate (ionomer) cements. At least 5 per cent of restorations needed to have failed over any period to allow close agreement of the two curves, with the slower failing materials requiring longer observation periods.

Continuous tooth eruption in Australian aboriginal skulls.

Increases in the distance from the cemento-enamel junction to the alveolar crest (CEJ-AC) have often been attributed to senile atrophy of the bone or to the effects of periodontitis, without reference to the condition of the alveolar crest. This study investigated the relationship between CEJ-AC distance, tooth wear, gender, site of the CEJ-AC measurements, and age in 161 pre-white-contact Australian aboriginal skulls. Individual teeth were included in the study when there was no evidence of dehiscence, periodontitis, or abscess cavity formation in the supporting alveolar bone. The CEJ-AC distances increased as the severity of attrition increased; in male skulls, CEJ-AC distances were greater than in female skulls for all categories of tooth wear. In general, CEJ-AC distances measured on the mesial aspects of teeth were greater than those recorded distally; lingual distances generally exceeded buccal recordings. The best explanation of these findings and similar reports in the anthropological literature is that continuous tooth eruption occurred without the concomitant coronal movement of alveolar bone. This conclusion has significant ramifications for anthropological, epidemiological, and clinical studies which use the CEJ and AC as reference points when measuring periodontal attachment loss (periodontitis).

Prediction of amalgam restoration longevity.

The purpose of the present study was to assess predictions of longevity for amalgam restorations using a fitted Weibull distribution against base estimates using actuarial methods. The 1345 restorations involved were from 100 members of the Royal Australian Air Force whose dental conditions had been monitored regularly over a minimum period of 10 years. Based on maximum likelihood estimates of the parameters of a Weibull distribution, Weibull curves could be determined and were found to be very close to actuarial survival curves established from the same data set. However, Weibull estimates based on survival experience of less than 5-6 years failed to predict long-term survival. Using the 6 year actuarial survival data, the predicted and observed survival curves disagreed by less than 10 per cent for every time period. Twenty-five per cent of restorations had failed for the 6 year data, compared to 22 per cent in these first 6 years for the full 17 year data set.

An analysis of the effect of tooth intrusion on the microvascular bed and fenestrae in the apical periodontal ligament of the rat molar.

An analysis of the rat apical periodontal ligament (PDL) microvascular bed and fenestrae was conducted to evaluate the effect of a continuous 1.0 N intrusive tooth load for 30 minutes. The microvascular bed consisted of postcapillary-sized venules, venous and arterial capillaries, and terminal arterioles. Intrusion produced significant increases (p less than 0.01) in vascular volume for postcapillary-sized venules and venous capillaries in three of the four animals. Arterial capillaries, overall, showed a statistically significant increase (p less than 0.01). The endothelial surface area (micron2 x 10(6)) per cubic millimeter of PDL responded variably in postcapillary-sized venules and venous capillaries but showed a strong trend to increase in arterial capillaries. After tooth intrusion a significant reduction (p less than 0.01) occurred in the number of fenestrae per square micrometer of endothelium in postcapillary-sized venules and venous capillaries. Fenestrae in the control PDL had a mean diameter of 51.5 nm +/- 0.6 (SE), whereas those on the intrusion side were smaller (p less than 0.05), measuring 49.9 nm +/- 0.4 (SE).

Tooth extrusion effects on microvessel volumes, endothelial areas, and fenestrae in molar apical periodontal ligament.

Extrusive tooth loads, simulating short-term orthodontic movements, have not previously been used for transmission electron microscopic quantification of their effects on the periodontal ligament vessels. In this study, a continuous extrusive load of 1.0 N, applied to the rat maxillary first molar for 30 minutes, produced statistically significant changes in the microvascular bed of the tensioned apical periodontal ligament. The mean vascular volume, as a percentage of apical periodontal ligament volume, increased (p less than 0.01) in postcapillary-sized venules, venous capillaries, arterial capillaries, and terminal arterioles from 16.6% to 22.3%, 2.0% to 2.7%, 0.4% to 1.0%, and 1.0% to 2.5%, respectively. Mean endothelial surface area per cubic millimeter of apical periodontal ligament tissue increased (p less than 0.01) in postcapillary-sized venules from 16.8 to 25.7 x 10(6) microns 2/mm3, in venous capillaries from 3.0 to 4.8 x 10(6) microns 2/mm3, and in arterial capillaries from 0.7 to 1.5 x 10(6) microns 2/mm3. The number of fenestrae per square micron of endothelium in postcapillary-sized venules, venous capillaries, and arterial capillaries showed a mean increase from 0.02 to 0.07, 0.11 to 0.31, and 0.02 to 0.21 fenestrae/microns 2, respectively (p less than 0.01). Fenestrae per cubic millimeter of periodontal ligament tissue also demonstrated a statistically significant increase with extrusion (p less than 0.01) in postcapillary-sized venules from 0.37 to 1.55 x 10(6) fenestrae/mm3, in venous capillaries from 0.27 to 1.34 x 10(6) fenestrae/mm3, and in arterial capillaries from 0.02 to 0.22 x 10(6) fenestrae/mm3. Fenestrae in control vessels had a mean diameter of 54.2 +/- 0.56 nm (SE) compared with 61.1 +/- 0.7 nm in tensioned vessels (p less than 0.01). This investigation demonstrates multiple ultrastructural changes in the periodontal ligament microvascular bed after tooth extrusion.

Periodontal disease in ancient populations.

Recent clinical and anthropological findings indicate that the conventional concept of the pathogenesis of periodontal disease requires review. The periodontal lesion has been defined as a generalised horizontal loss of crestal bone resulting from host immune and inflammatory responses triggered by the action of commensal bacteria, and the extension of gingivitis into the deeper periodontium to become periodontitis has been assumed to occur slowly but steadily over many years. Anthropological and clinical investigations reveal that the widespread loss of crestal tissue is relatively unusual and that lesions of the alveolus are commonly localised and severe. Longitudinal studies have shown that the disease progresses in bursts and is stable in both the gingivitis and periodontal modes in between the burst activity. The findings of the present study demonstrate that generalized horizontal periodontitis has been unusual and has not been responsible for tooth loss. Other factors responsible for deficient alveolar margins in dry bones have been overlooked in most studies, leading to overassessment of the incidence of periodontal disease in postmortem materials; the same assumptions have led to overassessment of periodontal disease in clinical studies and practice.

The costs of coronary artery surgery to the community.

The possible benefits obtained both for the community and patients following coronary artery bypass grafting (CABG) have been examined in 4001 patients (mean age 54 years, 14.8% female) who underwent CABG from 1971 to 1982 in the Cardiothoracic Surgical Unit of the Royal Adelaide Hospital. Assessment followed a fixed response format questionnaire sent to all patients with a total follow-up of 98.8%. The hospital mortality was 1.4% for the 10 year period with a fall from 4% in 1973 to 0.9% in 1981. Shifts in employment were assessed in survivors. At follow up, 548 patients who were previously employed had ceased full-time or part-time employment. This decrease in employment was attributed mainly to age. Analysis of retirement curves for the general male population and male patients showed a similar pattern but downward translation of 4% for the pre-operative group. A similar downward shift occurred following surgery. For female patients, performance of home duties improved from 159 patients on full home duties pre-operatively to 292 post-operatively. Visits to the doctor dropped in 50% of surviving patients. CABG has a low mortality. The community benefits by helping to maintain productivity and decreased cost for ongoing medical care.

Domperidone, metoclopramide, and placebo. All give symptomatic improvement in gastroesophageal reflux.

A double-blind crossover study was conducted of two gastric prokinetic drugs in 23 patients with gastroesophageal reflux. Patients were divided into two groups on the basis of a dual-isotope mixed-meal study of their gastric emptying (GE). Group I had normal GE and group II delayed GE. Nine gastrointestinal symptoms were assessed for frequency and severity before treatment. The trial had three 1-month treatment periods using metoclopramide 10 mg q.i.d., domperidone 20 mg q.i.d., or placebo on a random basis. Symptoms were reassessed at the end of each month. Taken as a whole, the group showed a significant symptomatic response in all three treatment periods (p less than 0.0001), but patients with delayed or normal GE did not differ significantly in their symptomatic response. Eleven patients complained of side effects with metoclopramide and three stopped therapy before the 1-month course was completed. Two patients described side effects with domperidone, including one woman with galactorrhea after 36 h of treatment. Three patients on placebo also complained of important side effects. We conclude that a significant placebo effect is present in the treatment of gastroesophageal reflux. No significant difference was demonstrated in symptomatic improvement between placebo, domperidone, and metoclopramide in this study.

Monocyte antibody-dependent cellular cytotoxicity in splenectomized subjects.

Monocyte antibody-dependent cellular cytotoxicity (ADCC) was determined in normal subjects by using human A1 erythrocytes and immune human anti-A1 antiserum. The experimental data were fitted to a mathematical model and the values for maximal cytotoxicity and monocyte numbers required to produce 15% specific cytotoxicity (MD15) were subsequently computed and compared with the values for these two parameters estimated from the dose response curves. The values for both were significantly associated, and the mathematical model permitted precise quantitation of cytotoxicity in instances where this was impossible by standard methods. Maximal monocyte ADCC was significantly reduced in a group of splenectomized subjects, whereas the MD15 was increased. These findings emphasize the possible influences of the method of quantitation of ADCC and provide one explanation for the apparent conflict of published data.

Twelve years of coronary artery surgery in South Australia.

Twelve years' results of coronary artery bypass surgery in South Australia have been reviewed. The preoperative assessment parameters and operative profiles of 4001 patients who underwent isolated coronary artery grafting between 1970 and 1982 have been examined. In addition, all surviving patients received a follow-up questionnaire; only 48 patients have remained untraced. Survival curves for the patient group have been calculated and compared with those for the Australian population. The risk factors which influenced long-term survival have been identified. Surviving patients described their anginal symptoms as diminished in 93% of cases at the time of review. When recurrent angina was described, 58% of patients experienced it within 12 months of the operation. Postoperative activity was improved in 71% of patients; 8% described a deterioration. A second operation was performed in 2.1% of patients. This study provides a comprehensive review of the efficacy of coronary artery bypass surgery both in the short and in the medium term.

Handicapped children: behavioural and co-ordination characteristics affecting the delivery of dental care.

Statistical analysis of data from a field survey of 132 handicapped children confirmed that a questionnaire approach is reliable in identifying children with potential behavioural and co-ordination problems within a dental environment. Assessment of the behaviour and co-ordination of 2,082 handicapped children aged 3-16 years, inclusive, suggested that approximately 53 per cent were manageable in a normal dental surgery and 79 per cent had the necessary co-ordination for routine dental care.

The dental care of handicapped children in South Australia.

Sixty-two per cent of handicapped children had a dentist willing to provide treatment; 55 per cent and 41 per cent were examined and were treated at least annually. Approximately 58 per cent were reported by their guardians to be manageable in general dental practice. Treatment was provided under general anaesthesia for 29 per cent of the children, although 39 per cent were considered by their guardians to require this procedure. Factors related to type and frequency of dental treatment are discussed.