Comparison of two interdental cleaning aids: A randomized clinical trial

AIM

The aim of this study was a comparison of the handling and acceptance of two kinds of interdental brushes (interdental brush with a handle [HB] and a newly invented interdental cleaning device [NB]).

METHODS AND MATERIALS

In a randomized crossover trial, 40 test subjects with an average number of 23.5 interdental areas were examined. At two appointments with a "washout" period of one week, the volunteers tried out both cleaning tools (HB and NB). They were asked to clean as many interdental spaces as possible. The percentage of spaces, which could be reached, is the IRI (Interdental Reachability Index). Furthermore, subjective impressions were determined.

RESULTS

The average IRI using HB was 64% compared to 80% using of NB (P<.001); 62.5% of the volunteers found the cleaning with HB painful and 15% the cleaning with NB. The subjective feeling after cleaning was 1.75 with NB compared to 2.2 with HB (P=.015), grading the feeling, from 1 for "very good" to 5 for "poor." The acceptance of regular interdental hygiene was rated 1.95 in the case of the NB and 2.85 in the case of the HB. After both appointments, the test subjects declared that they would use the NB 3.05 times and the HB 1.78 times a week.

CONCLUSION

This study shows that the test subjects reached more interdental spaces with NB than with the HB. NB can improve the usage of interdental brushes. Regarding subjective comfort, participants also favoured NB over HB.

[Faulty internal tube in a co-axial ventilation tube system: cause of a massive postoperative hypercapnia]

This article presents the case of a patient with massive postoperative hypercapnia during mechanical ventilation in the intensive care unit (ICU). With normal tidal volumes and clearly visible chest movements, adequate findings with regard to auscultation, oxygenation and correct respirator settings, no cause for the increasing hypercapnia was initially found; however, replacement of the respirator led to a return to normal carbon dioxide levels. When checking the replaced respirator a service technician found the cause of the respirator failure: the internal tube of the co-axial ventilation system was faulty leading to an increased dead space and rebreathing of carbon dioxide.

The effects of physical exercise on plasma levels of relaxin, NTproANP, and NTproBNP in patients with ischemic heart disease

The insulin-like and vasodilatatory polypeptide relaxin (RLX), formerly known as a pregnancy hormone, has gained interest as a potential humoral mediator in human heart failure. Controversy exists about the relation between plasma levels of RLX and the severity of heart failure. The present study was designed to determine the course of RLX, atrial, and brain natriuretic peptide (NT-proANP and NT-proBNP) during physical exercise in patients with ischemic heart disease (IHD) and to relate hormone levels to peak cardiac power output (CPO) as a measure of cardiopulmonary function with prognostic relevance. 40 patients with IHD were studied during right-heart-catheterization at rest and during supine bicycle ergometry. RLX, NTproBNP, and NTproANP were determined before, during exercise, and after recovery. NT-proANP and NT-proBNP levels increased during maximal charge, and recovery while RLX levels decreased. Cardiac power output at maximal charge correlated inversely with NTproANP and NTproBNP but positively with RLX. Patients with high degree heart failure (CPO < 1.96 W) had higher NTproANP and NTproB-NP and lower RLX levels than patients with low degree heart failure. While confirming the role of NTproANP and NTproBNP as markers for the severity of heart failure, the present data do not support the concept that plasma levels of RLX are related to the severity of myocardial dysfunction and that systemic RLX acts as a compensatory vasodilatatory response hormone in ischemic heart disease.

Focussing cellular function. Metabolic monitoring in perioperative and Intensive Care Medicine

In the clinical field microdialysis today is a routine technique for monitoring the chemistry of tissues and organs in physiological and pharmacological research on animals. In more than 10.000 papers on microdialysis research it is used to uncover physiological mechanisms and the influence of drugs in almost every organ of the body. Since the first papers describing microdialysis in the human brain microdialysis has become a technique for routine monitoring of energy metabolism especially in neurointensive care. This paper gives an account of the microdialysis technique describing its practical use and interpretation in monitoring energy metabolism and ischemia in different organs with respect to the field of perioperative and intensive care medicine. This article gives an overview over current results of clinical studies using microdialysis in critical care medicine and tries to focus on possible indications for clinical biochemical monitoring. However, despite numerous publications available microdialysis has not been shown to improve outcome of the patients yet.

Myocardial metabolic monitoring with the microdialysis technique during and after open heart surgery

BACKGROUND

Post-operative ischemia after coronary artery bypass grafting (CABG) is well described but effective intervention requires immediate diagnosis. One possible way of increasing efficacy of peri-operative myocardial monitoring is using the microdialysis technique.

METHODS

In 30 patients undergoing routine CABG, a microdialysis catheter was inserted in the left heart in an area of abnormal ventricular contraction. A second catheter was placed in normal tissue of the right ventricle. Microdialysis measurements were performed at time intervals before, during and 24 h after cardiopulmonary bypass (CPB) and retrospectively compared with standard clinical monitoring and clinical course.

RESULTS

During CPB, both ventricles showed signs of poor tissue oxygenation. Glycerol was significantly higher in the left myocardium (146 +/- 67 vs. 72 +/- 36 micromol/l) and the glucose/lactate ratio (GLR), as a marker of nutritional disorder of the right ventricle (41 +/- 15% vs. 67 +/- 17%, P < 0.05), had significantly better values at this time point. Myocardial lactate concentrations were significantly higher in the dyskinetic segments (2.82 +/- 0.81 vs. 1.5 +/- 0.81 microM). During this period, no abnormal clinical standard monitoring results were observed. Post-operative significantly increased lactate/pyruvate ratios of three patients were clinically associated with peri-operative myocardial infarction (108 +/- 67 vs. 38 +/- 9, P < 0.05). The lactate/pyruvate ratio started rising before any other standard monitoring tools showed abnormal values.

CONCLUSIONS

Peri-operative microdialytic measurements of parameters related to ischemia can be safely performed in a clinical setting, resulting in faster and more reliable detection of ongoing or new ischemia.

High myocardial lactate concentration is associated with poor myocardial function prior to cardiopulmonary bypass

AIM

This study was designed to analyse the relationship between myocardial lactate--determined by microdialysis--and hemodynamics during coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB).

METHODS

Twenty consecutive patients with coronary artery disease were enrolled for this prospective, observational study. Microdialysis measurements were performed in the apical region of the heart during periods of 15 to 20 min before, during, and after CPB; hemodynamics and plasma lactate concentrations were determined correspondingly. Correlation analysis revealed a relationship between myocardial lactate concentration and right ventricular ejection fraction at baseline (Spearman's r: 0.6; P=0.02). Patients were thus grouped according to the myocardial lactate concentration at baseline into a high-lactate group (2.5+/-0.7 mmol.l(-1), n=10) and low-lactate group (0.9+/-0.5 mmol.l(-1), n=10).

RESULTS

Preoperative left ventricular ejection fraction was not different between the groups (high-lactate group: 53+/-16%; low-lactate group: 57+/-15%; P=n.s.) Patients in the high-lactate-group had a lower stroke volume index (P=0.005) and right ventricular ejection fraction (P=0.04) before, and higher central venous and pulmonary artery pressures (P<0.01) after CPB. Plasma lactate was significantly higher during CPB in the high-lactate-group (P<0.05). No correlation was observed between myocardial and plasma lactate. Six patients in the high-lactate but none in the low-lactate-group needed inotropic support after weaning from CPB (P=0.01).

CONCLUSIONS

These data are suggestive of an association between subtle myocardial ischemia--detected by microdialysis--and perioperative myocardial dysfunction in patients undergoing CABG. The microdialysis technique may be a valuable adjunct for monitoring myocardial metabolism during cardiac surgery.

Metabolic stress during hypoglycaemia clamp assessed by microdialysis

AIM

Microdialysis allows the biochemical analysis of interstitial fluids as a bedside procedure. This technique is of interest to evaluate the glucose dependent metabolism in hypoglycaemic patients. It was the aim to perform subcutaneous and blood microdialysis during hypoglycaemic clamp experiments in 12 healthy young men to reveal basis data for critical care microdialysis practice.

METHODS

The hyperinsulinaemic clamp was induced with a continuous infusion of 1.5 mU min(-1) kg(-1) insulin (H-insulin, Hoechst, Frankfurt, Germany). A 20% dextrose solution simultaneously was infused at a variable rate to control blood glucose levels. For hypoglycaemia blood glucose levels were reduced to 40 mg/dL for a 30 min period. Glucose, lactate, pyruvate and glycerol concentrations were semicontinuously measured.

RESULTS

The absolute concentrations of glucose and glycerol in blood vs subcutaneous microdialysate were significant different during observation. Until the end of hypoglycaemia, glucose concentration in both compartments declined in parallel, followed by an increase thereafter. During the clamp the subcutaneous glycerol increased threefold, whereas blood glycerol rose with a delay of 15 min and increased only twofold. After the clamp in both compartments glycerol values normalized. The lactate-pyruvate-ratio persisted in normal range throughout the examination.

CONCLUSIONS

In our experiment subcutaneous lipolysis increased faster and more profound than blood microdialysis. We propose the microdialysis technique as an additional monitoring tool in hypoglycaemia patients.

Clinical biochemical tissue monitoring during ischaemia and reperfusion in major vascular surgery

BACKGROUND

Major vascular surgery with aortic cross-clamping is associated with temporary ischaemia of the lower limb due to lack of tissue blood flow. The present study was designed to determine if the short-term changes in cellular metabolism occurring during this situation can be detected by subcutaneous microdialysis. It was also hoped to ascertain if this new technique is useful in the continuous bedside monitoring of metabolism during aortic surgery.

METHODS

In a controlled clinical study 20 patients undergoing elective aortic surgery were monitored using microdialysis probes that were inserted in the subcutaneous tissue of the left lower limb and a non-ischaemic region (shoulder). Interstitial fluid was obtained and the concentrations of glucose and lactate during lower limb ischaemia and during reperfusion were measured and compared with concentrations observed in fluid obtained from the non-ischaemic control tissue.

RESULTS

Circulatory occlusion caused an immediate and significant decrease in the glucose/lactate ratio from 3.1+/-1.3 to 0.48+/-0.5 (P<0.05) that returned to preocclusion values within 2 h of commencing reperfusion.

CONCLUSION

We suggest that microdialysis may be used both to assess acute changes in tissue metabolism during ischaemic periods and also to act as an additional tool for the detection of peri-operative acute variations in limb blood flow.

Metabolic changes detected by microdialysis during endotoxin shock and after endotoxin preconditioning

OBJECTIVE

Preconditioning with low doses of endotoxin has been shown to induce endotoxin hyporesponsiveness. The present study was designed to assess the metabolic response of various tissues during endotoxemia and after pretreatment with endotoxin.

DESIGN

Controlled experimental animal study.

SETTING

Research laboratory of a university hospital.

MEASUREMENTS AND RESULTS

Ten pigs were randomly assigned to a control ( n = 5) or a treatment group ( n = 5), the latter receiving incremental doses of endotoxin 5-2 days prior the experiments. Apart from hemodynamics and oxygen transport variables, lactate, glucose, and glycerol were measured in muscle, subcutaneous fat, and hepatic tissue using microdialysis. Endotoxin was infused (1 micro g.kg.h) until the animals died. A significant increase in tissue lactate (eightfold) and glycerol (fivefold) was observed in the control animals. This effect was almost completely abolished in the endotoxin pretreated group. Endotoxin pretreatment had no significant effects on mean arterial pressure [56 (range 34-89) mmHg vs 70 (47-88) mmHg, n.s.] or cardiac output [4.8 (3.0-5.9) l/min vs 3.2 (2.1-4.2) l/min, n.s.], but significantly improved arterial pO(2) and pH ( P<0.05). Increase of oxygen extraction was higher in control animals [from 34% (range 24-47%) to 72% (range 61-79%)] compared to the pretreatment group [from 30% (range 22-42%) to 44% (range 34-50%), P<0.05]. Endotoxin pretreatment increased survival time from 5.3 h (5.0-5.8) to 8.0 h (7.0-8.5) ( P<0.05), respectively.

CONCLUSIONS

Microdialysis monitoring revealed that endotoxin preconditioning ameliorates the increase in tissue metabolism during endotoxemia, accompanied by decreased systemic oxygen demand despite unchanged global hemodynamics.

[Microdialysis as a procedure for evaluating intestinal hypoxia--an animal experiment approach]

Usual ICU monitoring of patients with abdominal pathology provides no detailed information about hepatosplanchnic haemodynamics or intestinal metabolism. In our animal experiment, the effects of systemic hypoxia on microdialysis measurements of the peritoneum in comparison with the ischiocrural muscle as reference were investigated in 7 rats. The parameter of interest was the course of glucose metabolism reflecting sympathoadrenergic activity during the experiment. Measurements were obtained at timed intervals at baseline, under hypoxia, and during reoxygenation. After induction of systemic hypoxia, the peritoneal microdialysis showed significantly higher levels of glucose in comparison with the ischiocrural muscle. The results indicate hypermetabolic activity or a hypersympathetic response of the bowel in response to hypoxic stress. In the clinical setting, the bowel has an important role in the development of multiorgan failure. Microdialysis may therefore be an interesting tool for the early detection of hypoxic metabolism during and after abdominal procedures.

[Continuous biochemical tissue monitoring during acute hypoxia]

Oxygen deficiency during critical illness is known to cause profound changes in cellular metabolism with subsequent organ dysfunction. Clinical treatment in these patients is focussed on rapid reoxygenation to avoid a prolonged impaired synthesis of cellular high-energy phosphates (ATP). The effect of this therapeutical intervention on the level of the cell, however, has not yet been objectivized. The aim of the present experimental study was to biochemically monitor different tissues during hypoxia and reoxygenation using in vivo microdialysis. Eighteen adult male CD-rats (412-469 g; Ivanovas, Kisslegg, Germany) were normoventilated under general anaesthesia (FiO2 = 0.21). Ten were then subjected to a period of hypoxia (FiO2 = 0.1, 40 min) and reoxygenated with FiO2 = 0.21, while eight control animals were continuously ventilated with FiO2 = 0.21. In addition to invasive haemodynamic monitoring, biochemical tissue monitoring was performed using CMA 20 microdialysis probes, which were inserted into the muscle (m), subcutaneous space (s), liver (l) and peritoneal cave (p) with semicontinuous analyses of lactate and pyruvate at intervals of 15 minutes. Hypoxia induced a significant decrease in mean arterial pressure compared to the control group (p < 0.05). At the same time significant increases in blood lactate (12.3 + 4.1 mmol/l (hypoxia) vs. 1.5 +/- 0.3 mmol/l (control); p < 0.05) and in negative base excess (17.3 + 7 mmol/l (hypoxia) vs. 2.6 + 1.8 mmol/l (control), p < 0.05) occurred. Compared to unchanged levels in the control animals, the interstitital lacate/pyruvate ratio in the investigation group rose to significantly higher values (455 + 199% of baseline (m), 468 + 148% (p), 770 + 218% (l) and 855 + 432% (s) (p < 0.05). An immediate return to the baseline values after the start of reoxygenation was noted in the L/P ratio during the observation period. Using microdialysis, it was possible to objectify the effect of oxygen deficiency and restoration on tissue metabolism. Regarding clinical and preclinical practice, microdialysis monitoring should be performed to include biochemical cellular effects as an additional target for therapeutical interventions.

[Microdialysis for metabolic monitoring during septicemia]

Currently, metabolic changes in ICU patients in critical states are determined mainly by indirect laboratory parameters (e.g. blood lactate). Microdialysis is a new means of performing metabolic monitoring that permits organ-specific objectification on the basis of interstitial fluid samples. Continuous endotoxin infusion was administered to 10 female pigs and, in addition to hemodynamic monitoring, lactate and glycerol in the subcutaneous, intramuscular and hepatic tissue were measured by microdialysis. The interstitial concentrations of lactate and glycerol rose significantly under endotoxaemia and showed an earlier increase than blood lactate levels. Microdialysis is simple to apply, appears to be a suitable means of obtaining important information about cellular metabolic changes in different tissues of the critically ill patient, and can detect subtle changes that laboratory parameters can identify only later and incompletely.

Effects of posture and positive airway pressure on plasma atrial natriuretic peptide and renal urodilatin excretion

AIMS

To determine whether a coupling of plasma atrial natriuretic peptide (ANP) and renal excretion of urodilatin (U(URO)V)--recently observed during supraphysiological concentrations of ANP--may also be detected during moderate changes in ANP levels, i.e. if ANP is increased by supine positioning and decreased by applying continuous positive airway pressure (CPAP).

MATERIAL AND METHODS

We investigated 10 healthy male volunteers, orally hydrated with 200 ml water/h, in a randomized crossover study for periods of 1 hour following 2 protocols. Protocol 1: sitting and supine position. Protocol 2: sitting with and without a CPAP of 8 cm H2O.

RESULTS

ANP increased ongoing from the sitting to the supine position (SIT-1: 13.2 +/- 4.7; SUP: 27.9 +/- 21.9 pg x ml(-1); p < 0.01) during protocol 1 and decreased after the onset of CPAP in seated subjects (SIT-2: 16.9 +/- 7.9; SIT-CPAP: 13.9 +/- 6.5 pg x ml(-1); p < 0.05) during protocol 2. U(URO)V decreased slightly, but not significantly, during protocol I (SIT-1: 63.9 +/- 21.7; SUP: 49.9 +/- 13.2 fmol x min(-1)) and remained unchanged after institution of CPAP in the sitting position (SIT-2: 68.5 +/- 25.2; SIT-CPAP: 68.5 +/- 50.2 fmol x min(-1)). Correlation analysis revealed no relationship between plasma ANP and U(URO)V.

CONCLUSIONS

Moderate variations in the levels of ANP in water-loaded volunteers do not induce parallel changes in the urinary excretion of urodilatin.

Effects of angiotensin II and the AT(1) receptor antagonist losartan on the renal excretion of urodilatin

BACKGROUND

The precise mechanisms regulating the natriuretic peptide urodilatin (ANP-95-126) remain to be defined. Renal excretion of urodilatin (U(URO)V) has been shown to be modified by variations in plasma sodium and renal perfusion pressure. This suggests a relationship between urodilatin and the renin-angiotensin system.

METHODS

We investigated the effects of angiotensin II (AII, 0.1 nmol/l) and the AT(1) receptor antagonist losartan (LS, 1 micromol/l) on U(URO)V and renal function in isolated rat kidneys perfused for 180 min in a closed circuit system. A further series employing a vasoconstricting concentration of endothelin-1 (ET-1, 0.01 nmol/l) was performed to explore the effects of vasoconstriction and glomerular filtration rate (GFR) on U(URO)V.

RESULTS

Urine flow (UV) and urinary sodium excretion (U(Na)V) decreased and renal vascular resistance (RVR) increased after treatment with AII (n = 5) in comparison with a control group (n = 6; p < 0.05). Treatment with LS (n = 5) and AII+LS (n = 5) had no significant effect on these parameters. GFR decreased after AII (p < 0.05) and was not significantly altered by other interventions. U(URO)V decreased after AII (p < 0.05) and was comparable to the control group after LS and AII+LS. ET-1 (n = 5) induced a significant increase in RVR and decreased UV and U(Na)V (p < 0.05). Point-to-point analysis revealed that the ET-1-induced vasoconstriction and the subsequent decrease in GFR had no effect on U(URO)V.

CONCLUSIONS

This suggests that vasoconstrictory concentrations of AII decrease U(URO)V in the isolated perfused rat kidney. The lack of effect of ET-1 on U(URO)V suggests that the AII-induced alterations in urodilatin excretion cannot be explained by vasoconstriction per se.

Early postoperative thrombolytic therapy after laparotomy

Early postoperative pulmonary embolism due to deep venous thrombosis has been reported to be associated with a mortality rate of approximately 46%. Administration of thrombolytic drugs is relatively contraindicated during this period so that conservative or surgical treatment can be considered as a therapeutical intervention. We report the case of a 68-year-old male patient who was subjected to systemic thrombolytic therapy due to pulmonary embolism on the first day after laparatomy.

Pentoxifylline improves circulatory and metabolic recovery after cardiopulmonary resuscitation

BACKGROUND

To evaluate the effectiveness of a bolus application of pentoxifylline (PTXF) at the beginning of CPR in a standardized resuscitation animal model.

METHODS AND RESULTS

In a laboratory model of cardiac arrest, 12 Wistar rats (382-413 g) were randomized into two groups. Both groups underwent 4 min of cardiopulmonary arrest induced by a transthoracic application of a fibrillating current of 10 mA. At the beginning of CPR, group one (n=6) received a bolus injection of 10 mg kg(-1) body weight PTXF versus sodium chloride in group two (controls: n=6). All animals developed a severe lactate acidosis during and after CPR but in PTXF treated animals acid-base values returned to baseline pattern. During return of spontaneous circulation (ROSC) in the PTXF group lactate concentration decreased from 13.4+/-2.1 to 1.9+/-0.7 mmol l(-1) within 60 min (P<0.01). In control animals, lactate values remained high (10.8+/-3.5 by 60 min, P<0.01). After bolus injection of PTXF pH increased from 6.93+/-0.06 to 7.29+/-0.13 within 60 min of ROSC versus 6.85+/-0.05 to 6.97+/-0.23 in sodium chloride treated animals (P<0.01). Within 5 min of ROSC, PTXF treated animals achieved higher oxygenation values (PTXF P(a)O(2)=216.9+/-62.5 mmHg, control 132. 2+/-15.1 mmHg, P<0.01).

CONCLUSIONS

Administration of PTXF at the beginning of CPR improved macrocirculation, acid-base status and arterial oxygenation.