Multi-isotope analysis reveals that feasts in the Stonehenge environs and across Wessex drew people and animals from throughout Britain.

The great henge complexes of southern Britain are iconic monuments of the third millennium BCE, representing great feats of engineering and labor mobilization that hosted feasting events on a previously unparalleled scale. The scale of movement and the catchments that the complexes served, however, have thus far eluded understanding. Presenting the largest five-isotope system archeological dataset (87Sr/86Sr, δ34S, δ18O, δ13C, and δ15N) yet fully published, we analyze 131 pigs, the prime feasting animals, from four Late Neolithic (approximately 2800 to 2400 BCE) complexes to explore the networks that the feasts served. Because archeological evidence excludes continental contact, sources are considered only in the context of the British Isles. This analysis reveals wide-ranging origins across Britain, with few pigs raised locally. This finding demonstrates great investment of effort in transporting pigs raised elsewhere over vast distances to supply feasts and evidences the very first phase of pan-British connectivity.

Expiratory airflow patterns in children and adults with cystic fibrosis.

STUDY OBJECTIVE: To determine whether tidal expiratory airflow patterns change with increasing airways obstruction in patients with cystic fibrosis. DESIGN: An observational study. SETTING: Lung function laboratory. PATIENTS: Sixty-four children and young adults with cystic fibrosis. MEASUREMENTS: After measuring FEV(1) and airways resistance using body plethysmography, each subject was seated and asked to mouth breathe through a pneumotachograph for 2 min. The collected data were analyzed, and three expiratory airflow pattern-sensitive indexes were computed. The first index was derived from the ratio of the time to reach peak expiratory flow to the total expiratory time (tPTEF/tE). The second index, Trs, was an estimate of the time constant of the passive portion of expiration. The third index, f1.gif" BORDER="0">, describes the slope of the whole post-peak expiratory flow pattern after scaling. RESULTS: Compared with FEV(1), the index tPTEF/tE was a poor indicator of airways obstruction (r(2) = 0.15, p = 0.002). Trs showed a strong relationship with the severity of airways obstruction (r(2) = 0.46, p < 0.001). Using f1.gif" BORDER="0">, the postexpiratory profile could be categorized into three shapes, and provided a good indicator of airways obstruction when linear and concave-shaped profiles occurred (r(2) = 0.42, p < 0.001). Convex-shaped flow profiles had to be treated separately and were indicative of normal lung function. CONCLUSIONS: In a cross-sectional study of patients with cystic fibrosis, increase in airways resistance above normal is reflected by quantifiable changes in the expiratory airflow pattern.

Analysis of expiratory tidal flow patterns as a diagnostic tool in airflow obstruction.

An index obtained from tidal expiration, the ratio of time to peak tidal expiratory flow (tPTEF) to expiratory time (tE), discriminates between groups with and without airflow obstruction in infants and children and correlates with other measurements of airflow obstruction in adults. The aim of this study was to determine whether the diagnosis of airflow obstruction could be made from an analysis of the later part of the expiratory tidal flow time curve, i.e beyond the maximum flow. One hundred and eighteen patients attending the lung function laboratory with a putative diagnosis of airflow obstruction were studied. From uncoached tidal breathing, measurements were made of the average time constant of the respiratory system (Trs) and extrapolated volume (EV). Forced expiratory spirometry and whole-body plethysmography were performed. In this cross-sectional study, Trs correlated with inspiratory airways resistance and forced expiratory volume in one second (FEV1), according to the linear regression equations, airway resistance (Raw)=3.03 Trs+1.2, r=0.65, p<0.001, and FEV1% predicted = 87.8-23.7 Trs, r=058, p<0.001. EV correlated positively with overinflation, functional residual capacity (FRC) % pred = 152 EV+103, r=0.68, p<0.001. This study shows that there is a relationship between these measurements made from analysis of tidal breathing and recognized measurements of airflow obstruction and overinflation.

Tidal expired airflow patterns in adults with airway obstruction.

Earlier studies have shown that time and flow indices derived from tidal expiratory flow patterns can be used to distinguish the severity of airway obstruction. This study was designed to address two aspects of tidal expiratory flow patterns: 1) how do expiratory flow patterns differ between subjects with normal and obstructed airways; and 2) can a sensitive index of airway obstruction be derived from these pattern differences? Tidal expiratory flow patterns from 66 adult subjects with varying degrees of airway obstructive disease with a forced expiratory volume in one second (FEV1) of 20-121% predicted were examined. In each subject, the expired flow pattern from each consecutive breath was scaled and then averaged together to create a single expired pattern. A detailed examination of the scaled flow patterns in 12 subjects (six with normal airways and six with airway obstruction) showed that the shape of the post-peak expiratory flow portion was different in the subjects with airway obstruction. A slope index, S, was derived from the scaled patterns and found to be sensitive to the severity of airway obstruction, correlating with FEV1 (% pred) with r2=0.74 (p<0.05, n=57). The S index also correlated (r2=0.36, p<0.05, n=47) with the functional residual capacity (FRC) (% pred) which was >100% in subjects with severe airway obstruction and lung overinflation. In subjects with normal airways, three further airflow patterns could be distinguished, which were different from the patterns seen in subjects with the severest airway obstruction. Scaled flow patterns from tidal expiration collected from uncoached subjects, can be used to derive an index of airway obstruction.

Difference between functional residual capacity and elastic equilibrium volume in patients with chronic obstructive pulmonary disease.

BACKGROUND: A study was performed to determine the elastic equilibrium volume (Vr) of the respiratory system in patients with chronic obstructive pulmonary disease (COPD). METHODS: Voluntary relaxed expiration from total lung capacity (TLC) was studied in three groups of subjects: seven patients with severe chronic airways obstruction (COPD), 10 normal subjects, and 15 subjects with restrictive disease. RESULTS: In the normal subjects and the patients with restrictive disease voluntary relaxed expiration from TLC stopped close to end tidal volume (FRC) and the volume expired in this manoeuvre was less than that expired in a slow vital capacity manoeuvre (SVC). In the patients with COPD the voluntary relaxed expiration continued beyond the end tidal volume (FRC) and the volume expired was not different from the SVC. Oesophageal (pleural) pressures and surface diaphragmatic EMG recordings in the patients with COPD supported the premise that relaxation was achieved. CONCLUSIONS: In patients with COPD, end tidal volume (FRC) is higher than the elastic equilibrium volume, Vr, of the respiratory system. This is in contrast to patients with restrictive disease and normal subjects in whom end tidal volume (FRC) is close to Vr. This study shows that, in patients with severe chronic obstructive pulmonary disease, Vr is at least as small as residual volume (RV).

Analysis of tidal expiratory flow pattern in the assessment of histamine-induced bronchoconstriction.

BACKGROUND: There are times in clinical practice when it would be useful to be able to assess the severity of airways obstruction from tidal breathing. Three indices of airways obstruction derived from analysis of resting tidal expiratory flow have previously been described: (1) Tme/TE = time to reach maximum expiratory flow/expiratory time; (2) Krs = decay constant of exponential fitted to tidal expiratory flow versus time curve; and (3) EV = extrapolated volume--that is, area under the curve when the fitted exponential is extrapolated to zero flow. In this paper a further index--dtr/TE, time from the beginning of expiration till the rapid decay of flow begins/expiratory time--is evaluated. The aim of this study was to assess the ability of these indices to detect mild airways obstruction. METHODS: A histamine bronchial provocation test was performed in 20 adult patients with a diagnosis of asthma or symptoms of cough and/or shortness of breath. Baseline forced expiratory volume in one second (FEV1), functional residual capacity (FRC), and specific inspiratory conductance (sGaw) were measured and the measurements repeated after the final inhalation of histamine. Expiratory flow patterns during quiet breathing over five consecutive representative breaths were analysed before and after histamine. The test was concluded in 12 subjects when FEV1 had decreased by 20% of the post saline value, and in the remaining eight after inhalation of 16 or 32 mg/ml histamine. RESULTS: FEV1, sGaw, FRC, Krs, EV, and dtr/TE were all different after histamine (paired t test). For Tme/TE no difference was shown. Change in EV detected change in end tidal volume but underestimated it compared with the change measured by body plethysmography. Percentage fall in Krs after histamine correlated with percentage fall in FEV1 (r = 0.527, Pearson correlation coefficient). This was of a similar order to the correlation between the percentage fall in sGaw and in FEV1 (r = 0.543). CONCLUSIONS: Analysis of expiratory tidal flow-time patterns predicted a decrease in FEV1 following histamine challenge as did measurement of sGaw. This analysis of tidal breathing would be useful in circumstances where forced expiratory manoeuvres are unreliable or inapplicable.

Effect of carbohydrate rich versus fat rich loads on gas exchange and walking performance in patients with chronic obstructive lung disease.

BACKGROUND: High calorie intakes, especially as carbohydrate, increase carbon dioxide production (VCO2) and may precipitate respiratory failure in patients with severe pulmonary disease. Energy obtained from fat results in less carbon dioxide and thus may permit a reduced level of alveolar ventilation for any given arterial blood carbon dioxide tension (PaCO2). METHODS: Ten patients with stable severe chronic obstructive lung disease underwent a six minute walk before and 45 minutes after taking 920 kcal of a fat rich drink, an isocalorific amount of a carbohydrate rich drink, and an equal volume of a non-calorific control liquid on three separate days, in a double blind randomised crossover study. Borg scores of the perceived effort to breathe were measured at the beginning and end of each six minute walk. Minute ventilation (VE2), VCO2, oxygen consumption (VO2), respiratory quotient (RQ), arterial blood gas tensions, and lung function were measured before and 30 minutes after each test drink. RESULTS: Baseline measurements were similar on all three test days and the non-calorific control drink resulted in no changes in any of the measured variables. The carbohydrate rich drink resulted in significantly greater increases in VE, VCO2, VO2, RQ, PaCO2, and Borg score and a greater fall in the distance walked in six minutes than the fat rich drink (mean fall after carbohydrate rich drink 17 m v 3 m after fat rich drink and the non-calorific control). The increase in VCO2 correlated significantly with the decrease in six minute walking distance and the increase in Borg score after the carbohydrate rich drink. The only significant change after the fat rich drink when compared with the non-calorific control was an increase in VCO2. CONCLUSIONS: Comparatively small changes in the carbohydrate and fat constitution of meals can have a significant effect on VCO2, exercise tolerance, and breathlessness in patients with chronic obstructive lung disease.

First pass lung uptake of bupivacaine: effect of acidosis in an intact rabbit lung model.

The first pass uptake, metabolism and recovery of bupivacaine were examined in an intact rabbit lung model using a multiple indicator technique with rapid sequential sampling. The rabbits were allocated to an acidotic group (pH 7.0-7.1) (n = 8) and a control group (n = 10) with normal pH. Bupivacaine recovery rates were not significantly different: median 93.2% (range 48.9-116.5%) and 94.5% (54.9-123.1%) in control and acidotic groups, respectively. Median peak percentage fractional concentrations of bupivacaine were greater in the acidotic group: 6.22% (2.5-7.65%) vs 4.1% (2.5-6.7%) (P less than 0.05). Median maximum instantaneous pulmonary percentage extraction was less in the acidotic animals than in animals with normal pH: 81.2% (47.1-91.9%) vs 91.0% (82.6-94.5%) (P less than 0.01). Median normalized mean percentage transit time was less in the acidotic group (245.3% (163.4-465.3%)) than in the control group (423.9% (313.9-740.4%)) (P less than 0.01). There was no evidence for bupivacaine metabolism by the lung. The results suggest that acidosis reduced bupivacaine lung uptake and increased its rate of passage through the lung, but did not influence overall drug recovery rates. This has clinical implications for bupivacaine related cardiac and cerebral toxicity.

The uptake of bupivacaine in an in situ isolated perfused rabbit lung preparation.

A double indicator technique has been used in an in situ isolated perfused rabbit lung model to examine the first pass effect of the lung on systemic bupivacaine concentrations. Bupivacaine (0.5 mg/kg) was given in two consecutive boluses to six in situ isolated perfused New Zealand White rabbit lung preparations. The mean recovery (first bolus) of bupivacaine was 62.6% +/- 6.3 (S.E.M.), and 63.7% +/- 10.2 (second bolus), suggesting bupivacaine accumulation in the lung. The average mean transit time for bupivacaine was 280.5% +/- 24.1 and 264.8% +/- 36.7 longer than ICG (Indocyanine Green) following the first and second boluses respectively (P less than 0.01). There were no differences in the first pass effect of the lung between the first and second boluses of bupivacaine. The profiles of the bupivacaine concentrations suggest that uptake is followed by accumulation and later back diffusion. This has implications for conditions that decrease the uptake and therefore increase the risk of systemic toxicity.

Breathing muscle activity during expiration in patients with chronic airflow obstruction.

During quiet ventilation in 10 patients with severe chronic airflow obstruction (AFO) there were large tidal swings of pleural pressure, 15.8 +/- 5.1 cmH2O, with high negative pressures achieved, 15.2 +/- 5.2 cmH2O. The pattern of pleural pressure mirrored that of tidal expiratory flow with a rapid rise to maximum of pleural pressure and flow at the beginning of expiration, a slow decline of both throughout most of expiration, and just before the onset of inspiration at flow reversal, a sharp fall in pleural pressure and expiratory flow. The shape of expiratory flow and pleural pressure tracings and the pattern of EMG recordings are compatible with loss of post-inspiratory muscle braking of flow. The generally negative pleural pressure and the EMG silence during expiration indicated relaxation of expiratory muscles throughout expiration. Extrapolation of the tidal expiratory flow curve to zero, and calculation of the area under the extrapolated curve showed the volume of dynamic hyperinflation to be a small proportion of the total increase in functional residual capacity above the predicted value in these patients.

Evaluation of a multigas anaesthetic monitor: the Datex Capnomac.

A laboratory investigation was carried out to evaluate the performance of the Datex Capnomac multigas anaesthetic agent analyser, with particular emphasis on accuracy, response and delay times, zero and gain stability and interference from water vapour. The analysis of anaesthetic vapours was less accurate than the analysis of CO2, O2 and N2O, but acceptable for clinical use. The response to square wave changes in gas composition was accurate at frequencies up to 60 per minute for CO2 and 30 per minute for O2, but with N2O and the anaesthetic vapours there was a decrease in accuracy at frequencies above 20 breaths/minute. The instrument appeared to be unaffected by water vapour.

Effects of dopamine and dobutamine on the distribution of pulmonary blood flow during lobar ventilation hypoxia and lobar collapse in dogs.

Hypoxic pulmonary vasoconstriction was induced in the left lower lobe of fifteen dogs by ventilating the lobe with 7% O2 or by absorption collapse, and the distribution of flow between the lobe and the remainder of the lung was measured with electromagnetic flow probes. The lobar to total blood flow ratio was reduced by lobar ventilation hypoxia and decreased further during lobar collapse. In seven dogs, an infusion of 20 micrograms kg-1 min-1 of dopamine produced an increase in total blood flow, an increase in pulmonary artery pressure (P less than 0.01), and an increase in lobar to total flow ratio (P less than 0.05) during both hypoxic states. There was a significant fall in arterial PO2 (P less than 0.01) during ventilation hypoxia. Similar changes in total and lobar to total flow ratio (P less than 0.01) were observed in eight dogs given 20 micrograms kg-1 min-1 of dobutamine, but there were no changes in pulmonary artery pressure. The greater increase in total flow (+ 111%) resulted in a marked increase in mixed venous PO2 and no significant changes in arterial PO2 in this group of dogs. It is concluded that both drugs produce an increase in lobar to total blood flow ratio and shunt fraction, but that the mechanisms causing the redistribution of flow may differ.

Cardiorespiratory effects of an inspiratory hold and continuous positive pressure ventilation in goats.

The cardiorespiratory effects of three different patterns of mechanical ventilation were compared in sixteen anaesthetized goats. Intermittent positive pressure ventilation (IPPV), with an inspiratory: expiratory (I:E) time ratio of 1:3, was compared with an inspiratory hold pattern (IPPVH), with an I:E ratio of 3:1, and with continuous positive pressure ventilation (CPPV) adjusted to produce the same mean airway pressure. In eight animals with normal lungs, IPPVH reduced VD/VT and PaCO2, but produced no changes in oxygenation. CPPV did not significantly alter the efficiency of gas exchange. In a further eight animals, with oleic acid-induced lung damage, both IPPVH and CPPV produced a decrease in both VD/VT and PaCO2. Qs/Qt was significantly reduced by both CPPV and IPPVH, but the effect was more marked with CPPV, and the PaO2 was significantly increased only by CPPV. The increased effectiveness of CPPV in increasing PaO2 in this model may have been due to the greater increase in end-expiratory lung volume produced by this pattern of ventilation.

The effect of physical training on exercise ability in adolescent idiopathic scoliosis.

Twenty subjects with adolescent idiopathic scoliosis, aged 11--17 years, were studied before spinal fusion. Half the patients underwent a programme of daily physical exercises for 6--10 weeks. Before and after this period all the patients carried out a range of lung function tests and a progressive exercise test. There were no significant differences in any of the results between the control group and the training group. The cardiac and respiratory complications of spinal fusion are therefore unlikely to be lessened by preoperative physical training, except in selected subjects.