Ventilatory responses after major surgery and high dependency care

BACKGROUND: Disturbed breathing during sleep, with episodic upper airway obstruction, is frequent after major surgery. Ventilatory responses to hypercapnia and hypoxia during episodes of airway obstruction are difficult to investigate because the usual measure, that of ventilation, has been attenuated by the obstruction. We simulated the blood gas stimulus associated with obstruction to allow investigation of the responses. METHODS: To assess ventilatory responses, we studied 19 patients, mean age 59 (19–79), first at discharge from high dependency care after major abdominal surgery and then at surgical review, ∼6 weeks later. Exhaled gas was analysed and inspired gas adjusted to simulate changes that would occur during airway obstruction. Changes in ventilation were measured over the following 45–70 s. Studies were done from air breathing if possible, and also from an increased inspired oxygen concentration. RESULTS: During simulated obstruction, hypercapnia developed similarly in all the test conditions. Arterial oxygen saturation decreased significantly more rapidly when the test was started from air breathing. The mean ventilatory response was 5.8 litre min(−2) starting from air breathing and 4.5 litre min(−2) with oxygen breathing. The values 6 weeks later were 5.9 and 4.3 litre min(−2), respectively (P=0.05, analysis of variance). There was no statistical difference between the responses starting from air and those on oxygen. CONCLUSIONS: After major surgery, ventilatory responses to hypercapnia and hypoxaemia associated with airway obstruction are small and do not improve after 6 weeks. With air breathing, arterial oxygen desaturation during simulated rebreathing is substantial

ASSESSMENT OF SOIL PROPERTIES AS AFFECTED BY FOUR LAND USE TYPES IN EGBEADA, SOUTH - EAST NIGERIA

The study was conducted to ascertain the influence of four land use types [plantain plantation (PP), cassava farm (CF), whistling pine forest (WPF) and fallow land (FL)] on soil properties of Egbeada in South-east, Nigeria. Stratified sampling technique was used in the collection of soil samples from the land-uses. Composite samples were collected from each land-use for routine and selected special laboratory analyses. Data generated were analyzed statistically using analysis of variance. Sand particles had a mean of 85.20 %, 85.80 %, 83.60 % and 78.80 % for soils under PP, CF, WPF, and FL, respectively. The pH(H2O) had mean of 6.35, 6.42, 5.36 and 5.81 soils under PP, CF, WPF, and FL while organic matter had mean of 2.94 % for PP and FL, 1.47 % for CF and 2.79 % for WPF. However, available Zn of the studied soils had mean of 8.7 mg kg-1, 6.8 mg kg-1, 5.3 mg kg-1 and 4.9 mg kg-1 in decreasing order of fallow land > whistling pine forest > plantain plantation > cassava farm, respectively. The organic matter under soils of cassava farm differed significantly (P = 0.05) with that of plantain plantation, whistling pine forest, and fallow land. The available Zn and Cu differed non-significantly among soils of the various land-uses. However, the result obtained from the study indicated that the different land-uses have affected the soils at a various rate

Leg blood flow measurements using venous occlusion plethysmography during head-up tilt

We tested whether venous occlusion plethysmography (VOP) is an appropriate method to measure calf blood flow (CBF) during head-up tilt (HUT). CBF measured with VOP was compared with superficial femoral artery blood flow as measured by Doppler ultrasound during incremental tilt angles. Measurements of both methods correlated well (r = 0.86). Reproducibility of VOP was fair in supine position and 30° HUT (CV: 11%–15%). This indicates that VOP is an applicable tool to measure leg blood flow during HUT, especially up to 30° HUT

Nasal continuous positive airway pressure improves myocardial perfusion reserve and endothelial-dependent vasodilation in patients with obstructive sleep apnea

<p>Abstract</p> <p>Background</p> <p>Obstructive sleep apnea (OSA) has been associated with cardiovascular disease (CVD), but whether OSA is an independent risk factor for CVD is controversial. The purpose of this study is to determine if patients with OSA have subclinical cardiovascular disease that is detectable by multi-modality cardiovascular imaging and whether these abnormalities improve after nasal continuous positive airway pressure (nCPAP).</p> <p>Results</p> <p>Of the 35 consecutive subjects with newly diagnosed moderate to severe OSA recruited from the Stanford Sleep Disorders Clinic, 20 patients were randomized to active vs. sham nCPAP. Active nCPAP was titrated to pressures that would prevent sleep disordered breathing based on inpatient polysomnography. OSA patients had baseline vascular function abnormalities including decreased myocardial perfusion reserve (MPR), brachial flow mediated dilation (FMD) and nitroglycerin-induced coronary vasodilation. Patients randomized to active nCPAP had improvement of MPR (1.5 ± 0.5 vs. 3.0 ± 1.3, p = 0.02) and brachial FMD (2.5% ± 5.7% vs. 9.0% ± 6.5%, p = 0.03) after treatment, but those randomized to sham nCPAP showed no significant improvement. There were no significant changes seen in chamber sizes, systolic and diastolic function, valvular function and coronary vasodilation to nitroglycerin.</p> <p>Conclusions</p> <p>Patients with moderate to severe OSA had decreased MPR and brachial FMD that improved after 3 months of nCPAP. These findings suggest that relief of apnea in OSA may improve microvascular disease and endothelial dysfunction, which may prevent the development of overt cardiovascular disease. Further study in a larger patient population may be warranted.</p