Effects of buffering in hypercapnia and hypercapnic hypoxemia

Anesthetized, paralyzed and mechanically ventilated pigs were exposed to extreme hypercapnia (Paco_2-20 kPa) at Fio₂ 0.4 for 480 min, with (n = 6) or without (n = 6) continuous infusion of isotonic buffers (bicarbonate and trometamol). Arterial pH was higher in buffered animals than controls, 7.21 ±0.01 vs 7.01±0.01 (mean ± s.e.mean, P < 0.01). Serum osmolality and Paco₂ did not differ between groups throughout the experiment. The hemodynamic response to hypercapnia was attenuated in the buffered group, who had lower heart rate, 133 ± 6 vs 189±12 min^-1 (P < 0.01), mean arterial pressure (MAP) 109 ± 4 vs 124 ± 4 mmHg (14.5 ± 0.5 vs 16.5 ± 0.5 kPa) (P < 0.05), mean pulmonary arterial pressure 16±1 vs 23 ± 1 mmHg (2.1 ±0.1 vs 3.1 ±0.1 kPa) (P < 0.01), and pulmonary vascular resistance (PVR) 249 ± 21 vs 343 ± 20 dyn s-cm^-5 (2490±210 vs 3430±200 μN-s-cm^-5) (P < 0.01), compared with the control group. Subsequently, both groups were exposed to hypercapnic hypoxemia by stepwise increases in Fio₂ (0.15, 0.10, 0.05) at 30-min intervals, while Fico₂ was kept at 0.2. PVR increased in both groups (P < 0.05) but, except for heart rate, all hemodynamic differences between the groups disappeared during hypoxia. At Fio₂ 0.15, buffered animals had higher arterial oxygen saturation (73 ± 5%) than the controls (55 ± 5%), (P < 0.05). The control animals died after 1–29 min (mean 14 min) at Fio₂ 0.10, while all buffered animals survived Fio₂ 0.10 with stable MAP (122 ± 14 mmHg (16.3 ± 1.9 kPa). The buffered animals died after 4–22 min (mean 15 min) at Fio₂ 0.05. We conclude that buffering to a pH of 7.21 attenuates the observed hemodynamic response in extreme hypercapnia and improves survival in hypercapnic hypoxemia.     

Electrocardiographic and Clinical Predictors of Torsades de Pointes Induced by Almokalant Infusion in Patients with Chronic Atrial Fibrillation or Flutter: A Prospective Study

The aim of this study was to identify predictors of torsades de pointes (TdP) in patients with atrial fibrillation (AF) or flutter exposed to the Class III antiarrhythmic drug almokalant. TdP can be caused by drugs that prolong myocardial repolarization. One hundred patients received almokalant infusion during AF (infusion 1) and 62 of the patients during sinus rhythm (SR) on the following day (infusion 2). Thirty-two patients converted to SR. Six patients developed TdP. During AF, T wave alternans was more common prior to infusion (baseline) in patients developing TdP (50% vs 4%, P < 0.01). After 30 minutes of infusion 1, the TdP patients exhibited a longer QT interval (493 ± 114 vs 443 ± 54 ms [mean ± SD], P < 0.01), a larger precordial QT dispersion (50 ± 74 vs 27 ± 26 ms, P < 0.05), and a lower T wave amplitude (0.12 ± 0.22 vs 0.24 ± 0.16 mV. P < 0.01). After 30 minutes of infusion 2, they exhibited a longer QT interval (672 ± 26 vs 489 ± 74 ms, P < 0.001), a larger QT dispersion in precordial (82 ± 7 vs 54 ± 52 ms, P < 0.01) and extremity leads (163 ± 0 vs 40 ± 34 ms, P < 0.001), and T wave alternans was more common (100% vs 0%, P < 0.001). Risk factors for development of TdP were at baseline: female gender, ventricular extrasystoles, and treatment with diuretics; and, after 30 minutes of infusion: sequential bilateral bundle branch block, ventricular extrasystoles in bigeminy, and a biphasic T wave. Patients developing TdP exhibited early during almokalant infusion a pronounced QT prolongation, increased QT dispersion, and marked morphological T wave changes.     

Dental state and functional capacity in 75-year-olds in three Nordic localities

summary The aims of the study were to compare dental state in three Nordic 75-year-old populations and to evaluate dental state as a marker of functional ageing. The study is part of a Nordic comparative study of 75-year-olds in Glostrup, Göteborg and Jyväskylä. In the dental studies, 411 subjects in Denmark, 308 in Sweden and 310 in Finland participated. Odontological history was obtained from interviews. Other methods, which are described elsewhere, were used to measure various functional parameters. In Goteborg, 23% of the 75-year-olds reported they were edentulous and 27% that they had more than 20 of their own teeth. The corresponding figures in Glostrup were 45% and 15% and in Jyväskylä 58% and 9%, respectively. In all three localities, economic factors and lifestyle factors, such as tobacco smoking, low physical activity and low social activity, were significant predictors for impaired dental health. The number of teeth was significantly associated with, for example, spirometry parameters, reaction time, body extention and body flexion in males. In females, significant associations were obtained with spirometry parameters, reaction time, handgrip, body extension and body flexion. Internordic differences regarding dental state were obvious. Dental state was associated with functional capacities. We suggest that dental state is a marker of functional capacity in elderly populations.     

Implantation of Active Can Implantable Defibrillators in the right Pectoral Region

Routinely the active can ICD is placed in the left side pectoral position, which theoretically gives optimal conditions for a low defibrillation threshold. Some patients, bowever, demand a right pectoral position, which possibly could result in a bigger defibrillation threshold. A right pectoral position was used in 3 of 85 active can ICDs implanted in our institution from 1994. the DFT was 12 J in two and 18 f in one patient. Thus, right pectoral implantation is feasible and offers an alternative approach in selected patients.     

Enterostomy in Patients with Primary Neuropathic Amyloidosis

Three patients with primary neuropathic amyloidosis are reported. They were all almost totally disabled by either diarrhea and incontinentia alvi or obstipation. In all three patients enterostomies were tried as a palliative treatment and the results of the operations have been very promising.     

Evaluation of a Transcutaneous Oxygen and Carbon Dioxide Monitor in a Neonatal Intensive Care Department

Transcutaneous-Po₂; (tc-Po₂ (tc-Pco₂) at 44^oC and transcutaneous-Pco₂) at 38, 42, 43 and 44^oC were measured with a currently available monitoring system (TCM222, Radiometer, Copenhagen) in 64 newborn infants with severe respiratory insufficiency during the first five days of life. Tc-Pco₂ at all four temperatures correlated better with arterial blood-Pco₂ (aB-Pco₂)> than tc-Po₂ with aB-Po2. However, the sensitivity and specificity of tc-Po₂ and tc-Pco₂ were similar with regard to maintaining aB-Po₂, and aB-Pco₂ within specified limits. Tc-Pco₂ increased relatively with increasing electrode temperature by a factor which was similar to the anaerobic temperature coefficient of Po₂, in blood. The coefficient of variation of duplicate measurements was 10 % for tc-Po₂ and 5 % for tc-Pco₂. Electrode drift after an average of 3 hours patient monitoring was 2%±6% (1SD) for tc-Pco₂, and -3 %±6 % for tc-Pco₂- We conclude that tc-Po₂ and tc-Pco₂ are a valuable supplement to arterial blood gas measurements, but the variable correlation with arterial blood gas values and the electrode drifts which may occur, mean that they cannot fully replace arterial sampling.     

Radionuclide Angiocardiography in Post-myocardial Infarction Patients

ABSTRACT One hundred and one representative post-myocardial infarction (MI) patients were investigated with radionuclide angiocardiography (RNA) and exercise test within 1 month of the MI and after 6 and 12 months. From the RNA were calculated the left ventricular ejection fraction (LVEF) and a quantified phase image, the phase standard deviation (phase-SD), representing the timing of the left ventricular contraction. The mean phase-SD was significantly higher among these patients (18°, 19° and 18°, respectively, at the three investigations) compared to phase-SD in normals (6°), indicating an impaired timing of the left ventricular (LV) contraction. At all three investigations a significant correlation was found between the phase-SD and the LVEF (r=0.58, r=-0.74 and r=-0.75, respectively) and the corrected QT interval (r=0.27, r=0.44 and r=0.39, respectively). Maximal serum ASAT in patients with their first MI correlated significantly to phase-SD. Low exercise capacity or unfavourable NYHA classification was associated with high phase-SD. Phase-SD higher than mean was also associated with significantly increased mortality during the follow-up year (P=0.0057). In conclusion, phase-SD, reflecting the timing of the LV contraction wave, is easily accessible and clinically relevant. It merits further investigation as a prognostic factor after an MI.