Cerebral oxygen saturation (rSO2) during cardiopulmonary bypass (CPB) measured using the INVOS oximeter closely correlates with baseline rSO2

Baseline cerebral regional saturation (rSO₂) measured using the INVOS 5100C (Medtronic, MN, USA) varies widely among patients with cardiac and/or renal diseases. To identify significant correlates of baseline rSO₂ and to investigate intraoperative rSO₂ changes, we conducted a retrospective study in 494 patients undergoing on-pump cardiovascular surgery. Correlations between preoperative blood laboratory test variables and baseline rSO₂ before anesthesia were examined. Intraoperative rSO₂ changes were analyzed. Of all the variables examined, log-transformed B-type natriuretic peptide (BNP) most significantly and negatively correlated with baseline rSO₂ (r = - 0.652, p < 0.0001). Intraoperatively, rSO₂ showed the lowest value during cardiopulmonary bypass (CPB) (median rSO₂: 56.2% during CPB vs. 63.9% at baseline, p < 0.0001). Although rSO₂ during CPB correlated positively with hemoglobin concentration and oxygen delivery during CPB (r = 0.192, p < 0.0001; and r = 0.172, p = 0.0001, respectively), it correlated much more closely with baseline rSO₂ (r = - 0.589, p < 0.0001). Thus, patients showing low baseline rSO₂ primarily associated with preoperatively high BNP continued to show low rSO₂ even during CPB independent of hemodynamics artificially controlled by CPB. Our findings suggest that low baseline rSO₂ in patients with high BNP due to cardiac and/or renal diseases is more likely to result from tissue edema causing alterations in optical pathlength and thus in calculated rSO₂ values, not readily modifiable with CPB, rather than actual cerebral hemodynamic alterations readily modifiable with CPB. These may partly explain why the INVOS oximeter is a trend monitor requiring baseline measures.

The effects of diuretic use and the presence of ascites on muscle cramps in patients with cirrhosis: a nationwide study

BACKGROUND

Administration of diuretics and the presence of ascites in patients with cirrhosis were reported to be associated with muscle cramps; however, the clinical evidence is limited. This study aimed to determine whether muscle cramps are a diuretic-induced complication and whether ascites was a factor related to muscle cramp.

METHODS

A total of 1064 adult patients with cirrhosis were enrolled from 10 hospitals in Japan between June 2017 and December 2018. A questionnaire regarding cramps was completed by all patients. The ratio of extracellular water (ECW) was analyzed using the bioelectrical impedance analysis. Logistic regression analysis was performed to analyze the effects of diuretic administration and the ECW ratio on cramps.

RESULTS

Patients using diuretics had a higher incidence rate, higher frequency, stronger pain, and longer duration of cramps than those who did not. In the multivariate analysis, diuretic administration and the ECW ratio values ≥ 0.4 were not significantly associated with the presence, frequency, intensity, or duration of cramps. However, in the case of patients limited to Child-Pugh B or C, diuretic use was significantly correlated with the cramp frequency.

CONCLUSIONS

These results demonstrated that muscle cramps were not a complication of diuretic use in patients with cirrhosis; however, in those limited to Child-Pugh B or C, diuretic use was a factor that affected the frequency of cramps. Moreover, no association was found between the presence of ascites and cramps.

Qualitative, Patient-Centered Assessment of Muscle Cramp Impact and Severity

BACKGROUND

There is an urgent need for new therapeutic options to treat muscle cramps; however, no patient-reported measures exist that capture the entire cramp experience. We conducted a qualitative study to assess the experience of patients suffering muscle cramps, aiming to understand what factors determine the impact cramps have in patients' lives to guide the development of a patient-centered outcome measure of cramp severity and impact.

METHODS

We enrolled patients with cramps due to several etiologies, including motor neuron disease, pregnancy-induced cramps, cirrhosis and hemodialysis, and idiopathic and exercise-induced cramps. Patients participated in semistructured interviews about their experiences with muscle cramps and their responses were recorded and transcribed. Data were analyzed with content analysis using data saturation to determine the sample size. We subsequently developed a conceptual framework of cramp severity and overall cramp impact.

RESULTS

Ten patients were interviewed when data saturation was reached. The cramp experience was similar across disease and physiological states known to cause muscle cramps. The main themes that compose the overall cramp impact are cramp characteristics, sleep interference, daytime activities interference, and the effect on mental health.

CONCLUSIONS

This framework will be used to develop a patient-reported outcome of cramp severity and impact.

Effect of furosemide on muscle cramps in patients with liver cirrhosis

BACKGROUND AND AIM

Patients with cirrhosis usually experience muscle cramps of varying severity. Although diuretics have been reported to cause muscle cramps, clinical evidence is limited. Also, it has been pointed out that the use of diuretics is associated with the progression of sarcopenia in patients with cirrhosis. We conducted a questionnaire survey to clarify the effects of diuretics and skeletal muscle loss on muscle cramps.

METHODS

Overall, we enrolled 152 adults with cirrhosis in this study. Cramp questionnaires were obtained after informed consent. Study variables (demographics, physical findings, serum metabolic panel, and drugs taken that affect muscle cramps) were extracted from medical records. Body composition, including muscle volume, was analyzed using a bioelectrical impedance analysis method, and muscle strength (handgrip) was evaluated at enrollment. Cross-sectional skeletal muscle area was evaluated on computed tomography imaging at the L3 vertebral level to investigate the relationship between muscle cramps and sarcopenia.

RESULTS

The proportion of furosemide administration was higher in patients with cramping compared with those without. On a multivariate logistic regression analysis, furosemide use was a significant factor in the presence of muscle cramps. Furthermore, regarding factors contributing to muscle cramp severity, furosemide use was extracted by multivariate logistic regression analysis. In the presence or severity of muscle cramps, skeletal muscles did not show any significant difference.

CONCLUSIONS

Furosemide use for patients with cirrhosis was considered a risk factor for occurrence and severity of muscle cramps. On the other hand, skeletal muscle mass loss was not associated with muscle cramps.

Muscle cramps: A comparison of the two-leading hypothesis

Exercise-Associated Muscle Cramps (EAMC) are a common painful condition of muscle spasms. Despite scientists tried to understand the physiological mechanism that underlies these common phenomena, the etiology is still unclear. From 1900 to nowadays, the scientific world retracted several times the original hypothesis of heat cramps. However, recent literature seems to focus on two potential mechanisms: the dehydration or electrolyte depletion mechanism, and the neuromuscular mechanism. The aim of this review is to examine the recent literature, in terms of physiological mechanisms of EAMC. A comprehensive search was conducted on PubMed and Google Scholar. The following terminology was applied: muscle cramps, neuromuscular hypothesis (or thesis), dehydration hypothesis, Exercise-Associated muscle cramps, nocturnal cramps, muscle spasm, muscle fatigue. From the initial literature of 424 manuscripts, sixty-nine manuscripts were included, analyzed, compared and summarized. Literature analysis indicates that neuromuscular hypothesis may prevails over the initial hypothesis of the dehydration as the trigger event of muscle cramps. New evidence suggests that the action potentials during a muscle cramp are generated in the motoneuron soma, likely accompanied by an imbalance between the rising excitatory drive from the muscle spindles (Ia) and the decreasing inhibitory drive from the Golgi tendon organs. In conclusion, from the latest investigations there seem to be a spinal involvement rather than a peripheral excitation of the motoneurons.

Negative Dialysate to Sodium Gradient Does not Lead to Intracellular Volume Expansion Post Hemodialysis

Introduction

Intradialytic hypotension remains the most common complication of routine outpatient hemodialysis treatments. There is debate as to the optimum dialysate sodium concentration, with hypotonic dialysates potentially causing intracellular swelling and hypertonic ones intracellular dehydration.

Methods

Multi-frequency bioimpedance was used to assess extracellular and intracellular fluid volumes in 53 adult hemodialysis patients. Dialysate sodium was checked by ion electrophoresis.

Results

The mean decrease in extracellular volume and intracellular volumes were 1.01 ±0.09 and 0.88 ±0.18 kg, respectively. The median dialysate to sodium gradient was −3 mmol/L (−1 to −6), with a median dialysate sodium of 136 mmol/L (136–138). There was no association between changes in body fluid composition and sodium concentrations, or gradients. The mean difference between dialysate sodium prescribed and delivered was 2.4 ±0.8 mmol/L.

Conclusions

In this study we were unable to demonstrate a relationship between predialysis serum sodium and the dialysate sodium prescribed and changes in extracellular or intracellular fluid volumes. However this study showed that using a negative sodium gradient, patients can be successfully ultrafiltrated without setting up intracompartmental fluid gradients. The caveat is that the prescribed dialysate to serum sodium gradient may differ from the actual gradient.

Measurement of Cardiac Output and Blood Volume During Hemodialysis with Fluorescent Dye Dilution Technique

Intradialytic hypotensive events (IDH) accompanied by deleterious decreases of the cardiac output complicate up to 25% of hemodialysis treatments. Monitoring options available to track hemodynamic changes during hemodialysis have been found ineffective to anticipate the occurrence of IDH. We have assembled opto-electronic instrumentation that uses the fluorescence of a small bolus of indocyanine green dye injected in the hemodialysis circuit to estimate cardiac output and blood volume based on indicator dilution principles in patients receiving hemodialysis. The instrument and technique were tested in 24 adult end-stage renal failure subjects during 64 hemodialysis sessions. A single calibration factor could be used across subjects and across time. Intra-subject variability of the measurements over time was <10%. Stroke volume index (SVI) (mean ± SEM = 34 ± 1 vs. 39 ± 2 mL m^-2) and central blood volume (CBV) index (783 ± 36 vs. 881 ± 33 mL m^-2) were lower at the beginning of the sessions in which IDH eventually occurred. Cardiac index, SVI, and CBV index decreased with hemodialysis in all treatment sessions but the decrease was more intense in the IDH sessions. We conclude that hemodynamic monitoring can be implemented in patients receiving hemodialysis with minimal disruption of the treatment and could help understand intradialytic hypotension.

Muscle cramps in liver disease

Muscle cramps are common in patients with liver disease and adversely influence quality of life. The exact mechanisms by which they occur remain unclear, although a number of pathophysiological events unique to liver disease may contribute. Clinical studies have identified alterations in 3 areas: nerve function, energy metabolism, and plasma volume/electrolytes. Treatments have focused on these particular areas with varied results. This review will focus on the clinical features of muscle cramps in patients with liver disease and review potential mechanisms and current therapies.

Inflatable external upper and lower leg compression improves stroke volume and peripheral perfusion during central hypovolemia in healthy volunteers

Aim: To determine whether external leg compression (ELC) around the legs could prevent and restore central hypovolemia induced by head-up tilt (HUT) maneuver. Materials & methods: The dynamic effect of ELC was determined using 50 cm H2O inflation pressure. HUT was performed without ELC (control model), with ELC inflated before HUT (prevention model) and after HUT (restore model). Results: The decrease in stroke volume (SV) during the prevention model versus control model was 17 ± 3% versus 27 ± 3%. The restore model increased SV by 24 ± 2%. Similarly, peripheral perfusion measured by perfusion index (PI) and tissue oxygen saturation (STO2) was smaller in the prevention model than in the control model (PI: 65 ± 3% vs 79 ± 2%; STO2: 4 ± 1% vs 9 ± 1%). In the restore model, PI increased by 117 ± 24% and STO2 increased by 3 ± 1%. Conclusion: In this study, inflatable ELC around the legs was able to prevent and restore SV and peripheral perfusion in a model of acute central hypovolemia.

Impact of dry weight determined by calf bioimpedance ratio on carotid stiffness and left ventricular hypertrophy in hemodialysis patients

Our previous study has shown that modification of bioimpedance technique by the measurement of bioimpedance ratio in the calf (calf-BR) was a simple and practical method in assessing fluid status in hemodialysis patients. However, the consequences of periodical dry weight (DW) adjustment under the guidance of calf-BR on target organ damage have not been investigated. One hundred fifteen hemodialysis patients were enrolled in this pilot trial. Patients were divided into bioimpedance group and control group according to their dialysis schedule. In the bioimpedance group, DW was routinely adjusted under the guidance of calf-BR every 3 months. In the control group, the assessment of DW remained a clinical judgment. Carotid stiffness, left ventricular mass index (LVMI), and calf-BR were measured at baseline and at the 12th month in both groups. Home blood pressure (BP) was monitored monthly. Episodes of dialysis-related adverse events were recorded. No significant differences were observed in parameters between the two groups at baseline. Compared with the control group, the bioimpedance group had significantly lower values in terms of the annual averages of systolic home BP (147.4 ± 15.3 mm Hg vs. 152.6 ± 16.9 mm Hg, P = 0.019), carotid stiffness index β (10.7 ± 3.3 vs. 12.2 ± 3.1, P = 0.003), LVMI (155.21 ± 15.64 g/m(2) vs. 165.17 ± 16.76 g/m(2) , P < 0.001), and the percentage of individuals with calf-BR over target range (P = 0.040) at month 12, with less annual averages of antihypertensive medications used and lower frequency of intradialytic hypotension, muscle cramps, or clotted angioaccess. Continued DW control achieved by periodical calf-BR measurement improved arterial stiffness and left ventricular hypertrophy with good tolerability in hemodialysis patients.

Pneumatic compression devices during hemodialysis: a randomized crossover trial

BACKGROUND

Maintenance of central blood volume (CBV) is essential for hemodynamic stability during hemodialysis (HD), though preservation of CBV is poorly understood. Pneumatic compression devices (PCDs) during HD may help maintain CBV.

METHODS

We performed a randomized, crossover trial to determine the effect of PCDs on CBV during HD. Patients underwent two consecutive mid-week HD sessions, randomized to begin the first session either with or without PCDs [stratified by intradialytic hypotension (IDH)-prone status]. The primary outcome was change in CBV during HD. The secondary outcomes were change in other hemodynamic and volume status parameters.

RESULTS

Fifty-one patients (median age 65 years, 75% male, 22% IDH-prone) were randomized; forty-six completed the study. During HD, the median change in CBV for PCD and control sessions was -0.08 versus -0.05 L (P = 0.62). There was no difference in the change in cardiac output (CO) (-0.63 versus -0.49 L/min, P = 0.78) or systemic vascular resistance (SVR) (+1.30 versus +1.55 mmHg/L/min, P = 0.67) for PCDs versus control. Based on the bioimpedance measurements, patients were not volume overloaded pre-dialysis. There was a greater reduction in total body water (TBW) (-2.6 versus -2.3 L, P = 0.05) and intracellular fluid (ICF) volume (-1.3 versus -1.1 L, P = 0.03), and no difference in change in the extracellular fluid (ECF) volume (1.3 versus 1.2 L, P = 0.09) with PCDs versus control. Similar results were observed in IDH-prone patients.

CONCLUSIONS

Compared with standard of care, PCDs have no effect on intradialytic hemodynamic parameters, including CBV, although they may allow greater capacity for fluid removal. Further studies are required to better understand physiological and hemodynamic changes in patients during HD.

When is the best moment to assess the ankle brachial index: pre- or post-hemodialysis?

BACKGROUND

Cardiovascular disease is an important cause of death in patients on dialysis. Peripheral arterial disease (PAD) is a prognostic factor for cardiovascular disease. The ankle brachial index (ABI) is a noninvasive method used for the diagnosis of PAD. The difference between ABI pre- and post-dialysis had not yet been formally tested, and it was the main objective of this study.

METHODS

The ABI was assessed using an automated oscillometric device in incident patients on hemodialysis. All blood pressure readings were taken in triplicate pre- and post-dialysis in three consecutive dialysis sessions (times 1, 2, and 3).

RESULTS

One hundred and twenty-three patients (85 men) aged 53 ± 19 years were enrolled. We found no difference in ABI pre- and post-dialysis on the right or left side, and there was no difference in times 1, 2, and 3. In patients with a history of PAD, the ABI pre- versus post-dialysis were of borderline significance on the right side (p = 0.088).

CONCLUSION

ABI measured pre- and post-dialysis presented low variability. The ABI in patients with a history of PAD should be evaluated with caution. The applicability of the current method in predicting mortality among patients on hemodialysis therefore needs further investigation.

Extravascular lung water index: A new method to determine dry weight in chronic hemodialysis patients

To assess the dry weight of chronic hemodialysis (HD) patients, the extravascular lung water index (ELWI) as a volume parameter was investigated to identify fluid overload. Forty-two patients (30 males, 12 females) with a mean age of 55.7+/-13.0 years who were clinically not overhydrated were connected to the PiCCO system before starting HD treatment. We determined ELWI (normal range 3-7 mL/kg) and the following parameters: global end-diastolic volume index (GEDI, normal range 680-800 mL/m(2)) and intrathoracic blood volume index (ITBI, normal range 850-1000 mL/m(2)) before and after HD to assess the volume status. Brain natriuretic peptide (BNP), aldosterone, and renin as vasoactive hormones were measured at the beginning and at the end of HD treatment as well. In 28 of the 42 patients (67%), elevated values of ELWI were found, indicating interstitial volume overload. There were significant correlations between ELWI and cardiac function index (p=0.003; Pearson's coefficient -0.451), global ejection fraction (p=0.012; Pearson's coefficient -0.389), ITBI (p=0.004; Pearson's coefficient 0.437), and GEDI (p=0.004; Pearson's coefficient 0.437). No significant relations among ELWI and mean arterial pressure (MAP), BNP, aldosterone, and renin were found. In conclusion, the use of ELWI is safe in chronic HD patients and identifies fluid-overloaded patients, who show no obvious signs of hypervolemia. The determination of ELWI is an excellent method to quantify the exact volume in chronic HD patients.

Psycho-educational strategies to promote fluid adherence in adult hemodialysis patients: a review of intervention studies

BACKGROUND

We reviewed psycho-educational intervention studies that were designed to reduce interdialytic weight gain (IDWG) in adult hemodialysis patients. Our goals were to critique research methods, describe the effectiveness of tested interventions, and make recommendations for future research.

METHODS

Medline, PsychInfo, and the Cumulative Index to Nursing and Applied Health (CINAHL) databases were searched to identify empirical work. Each study was evaluated in terms of sample, design, theoretical framework, intervention delivery, and outcome.

RESULTS

Nine studies were reviewed. Self-monitoring appears to be a promising strategy to be considered to reduce IDWG. Theory was not usually used to guide interventions, designs generally had control groups, interventions were delivered individually, more than one intervention was delivered at a time, the duration of the intervention varied greatly, there was no long-term follow-up, IDWG was the only outcome, and IDWG was operationalized in different ways.

CONCLUSIONS

Theoretical models and methodological rigor are needed to guide future research. Specific recommendations on design, measurement, and conceptual issues are offered to enhance the effectiveness of future research.