Live birth sex ratios and father's geographic origins in Jerusalem, 1964-1976.

OBJECTIVE: To examine whether ancestry influenced sex ratios of offspring in a birth cohort before parental antenatal sex selection influenced offspring sex. METHODS: We measured the sex ratio as the percent of males according to countries of birth of paternal and maternal grandfathers in 91,459 live births from 1964 to 1976 in the Jerusalem Perinatal Study. Confidence limits (CI) were computed based on an expected sex ratio of 1.05, which is 51.4% male. RESULTS: Of all live births recorded, 51.4% were male. Relative to Jewish ancestry (51.4% males), significantly more males (1,761) were born to Muslim ancestry (54.5, 95% CI = 52.1-56.8, P = 0.01). Among the former, sex ratios were not significantly associated with paternal or maternal age, education, or offspring's birth order. Consistent with a preference for male offspring, the sex ratio decreased despite increasing numbers of births over the 13-year period. Sex ratios were not affected by maternal or paternal origins in North Africa or Europe. However, the offspring whose paternal grandfathers were born in Western Asia included fewer males than expected (50.7, 50.1-51.3, P = 0.02), whether the father was born abroad (50.7) or in Israel (50.8). This was observed for descendents of paternal grandfathers born in Lebanon (47.6), Turkey (49.9), Yemen & Aden (50.2), Iraq (50.5), Afghanistan (50.5), Syria (50.6), and Cyprus (50.7); but not for those from India (51.5) or Iran (51.9). The West Asian group showed the strongest decline in sex ratios with increasing paternal family size. CONCLUSIONS: A decreased sex ratio associated with ancestry in Western Asia is consistent with reduced ability to bear sons by a subset of Jewish men in the Jerusalem cohort. Lower sex ratios may be because of pregnancy stress, which may be higher in this subgroup. Alternatively, a degrading Y chromosome haplogroup or other genetic or epigenetic differences on male germ lines could affect birth ratios, such as differential exposure to an environmental agent, dietary differences, or stress. Differential stopping behaviors that favor additional pregnancies following the birth of a daughter might exacerbate these lower sex ratios.

Cognitive performance in irritable bowel syndrome: evidence of a stress-related impairment in visuospatial memory.

BACKGROUND: Central nervous system (CNS) dysfunction is a prominent feature of the functional gastrointestinal (GI) disorder, irritable bowel syndrome (IBS). However, the neurobiological and cognitive consequences of key pathophysiological features of IBS, such as stress-induced changes in hypothalamic-pituitary-adrenal (HPA)-axis functioning, is unknown. Our aim was to determine whether IBS is associated with cognitive impairment, independently of psychiatric co-morbidity, and whether cognitive performance is related to HPA-axis function. METHOD: A cross-sectional sample of 39 patients with IBS, a disease control group of 18 patients with Crohn's disease (CD) in clinical remission and 40 healthy age- and IQ-matched control participants were assessed using the Paired Associates Learning (PAL), Intra-Extra Dimensional Set Shift (IED) and Spatial Working Memory (SWM) tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and a computerized Stroop test. HPA-axis function was determined by measuring the cortisol awakening response (CAR). RESULTS: IBS patients exhibited a subtle visuospatial memory deficit at the PAL six- pattern stage (p = 0.03), which remained after psychiatric co-morbidity was controlled for (p = 0.04). Morning cortisol levels were lower in IBS (p = 0.04) and significantly associated with visuospatial memory performance within IBS only (p = 0.02). CONCLUSIONS: For the first time, altered cognitive function on a hippocampal-mediated test of visuospatial memory, which was related to cortisol levels and independent of psychiatric co-morbidity, has been identified in IBS. Visuospatial memory impairment may be a common, but currently neglected, component of IBS. Further elucidation of the nature of this impairment may lead to a greater understanding of the underlying pathophysiology of IBS, and may provide novel therapeutic approaches.

Global epidemiology of hepatitis B virus infection: new estimates of age-specific HBsAg seroprevalence and endemicity.

OBJECTIVE: Chronic hepatitis B virus infection is one of the most serious infections and a major risk factor for deaths from cirrhosis and liver cancer. We estimate age-, sex- and region-specific prevalence of chronic HBV infection and calculate the absolute number of persons being chronically infected. METHODS: A systematic review of the literature for studies reporting HBV infection was conducted and worldwide HBsAg seroprevalence data was collected over a 27-year period (1980-2007). Based on observed data, age-specific prevalence and endemicity were estimated on a global level and for all world regions for 1990 and 2005 using an empirical Bayesian hierarchical model. FINDINGS: From 1990 to 2005, the prevalence of chronic HBV infection decreased in most regions. This was particularly evident in Central sub-Saharan Africa, Tropical and Central Latin America, South East Asia and Central Europe. Despite this decrease in prevalence, the absolute number of HBsAg positive persons increased from 223 million in 1990 to 240 million in 2005. Age-specific prevalence varied by geographical region with highest endemicity levels in sub-Saharan Africa and prevalence below 2% in regions such as Tropical and Central Latin America, North America and Western Europe. Asian regions showed distinct prevalence patterns with lower intermediate prevalence in South Asia, but up to 8.6% HBsAg prevalence in East Asia. Strong declines were seen in South East Asian children. CONCLUSION: Declines in HBV infection prevalence may be related to expanded immunization. The increasing overall number of individuals being chronically infected with HBV, and the widespread global differences in HBV prevalence call for targeted approaches to tackle HBV-related mortality and morbidity. HBV infection prevalence data are needed at country and sub-national level to estimate disease burden and guide health and vaccine policy.

Enhanced slow wave sleep and improved sleep maintenance after gaboxadol administration during seven nights of exposure to a traffic noise model of transient insomnia.

Slow wave sleep (SWS) has been reported to correlate with sleep maintenance, but whether pharmacological enhancement of SWS also leads to improved sleep maintenance is not known. Here we evaluate the time-course of the effects of gaboxadol, an extra-synaptic gamma-aminobutyric acid (GABA) agonist, on SWS, sleep maintenance, and other sleep measures in a traffic noise model of transient insomnia. After a placebo run-in, 101 healthy subjects (20-78 y) were randomized to gaboxadol (n = 50; 15 mg in subjects <65 y and 10 mg in subjects ≥65 y) or placebo (n = 51) for 7 nights (N1-N7). The model caused some disruption of sleep initiation and maintenance, with greatest effects on N1. Compared with placebo, gaboxadol increased SWS and slow wave activity throughout N1 to N7 (p < 0.05). Gaboxadol reduced latency to persistent sleep overall (N1-N7) by 4.5 min and on N1 by 11 min (both p < 0.05). Gaboxadol increased total sleep time (TST) overall by 16 min (p < 0.001) and on N1 by 38 min (p < 0.0001). Under gaboxadol, wakefulness after sleep onset was reduced by 11 min overall (p < 0.01) and by 29 min on N1 (p < 0.0001), and poly-somnographic awakenings were reduced on N1 (p < 0.05). Gaboxadol reduced self-reported sleep onset latency overall and on N1 (both p < 0.05) and increased self-reported TST overall (p < 0.05) and on N1 (p < 0.01). Subjective sleep quality improved overall (p < 0.01) and on N1 (p < 0.0001). Increases in SWS correlated with objective and subjective measures of sleep maintenance and subjective sleep quality under placebo and gaboxadol (p < 0.05). Gaboxadol enhanced SWS and reduced the disruptive effects of noise on sleep initiation and maintenance.

Effects of upper-limb immobilisation on driving safety.

Doctors are frequently asked by patients whether it is safe to drive with an upper limb immobilised in a cast. In the literature there are no objective measurements of the effects of upper-limb immobilisation upon driving performance. Eight healthy volunteers performed four 20-min driving circuits in a driving simulator (STISIM 400W), circuits 1 and 4 without immobilisation and circuits 2 and 3 with immobilisation. Immobilisation involved a lightweight below-elbow cast with the thumb left free. Volunteers were randomised to right or left immobilisation for circuit 2, and the contralateral wrist was immobilised for circuit 3. Circuits included urban and rural environments and specific hazards (pedestrians crossing, vehicles emerging from a concealed entrance, traffic lights changing suddenly, avoidance of an oncoming vehicle in the driver's carriageway). Limb immobilisation led to more cautious rural and urban driving, with less adjustment of speed and lateral road position than when unrestricted. However when responding to hazards immobilisation caused less safe driving, with higher speeds, a greater proximity to the hazard before action was taken and less steering adjustment. The effects of restriction upon performance were more prevalent and severe with right-arm immobilisation. Upper-limb immobilisation appears to have little effect on the ability to drive a car unchallenged, but to adversely affect responses to routine hazards. Advice on ability to drive safely should be cautious, as the impact of immobilisation appears to be more subtle and wide ranging than previously thought.

Serial memory for sound-specified locations: effects of spatial uncertainty and motor suppression.

According to Parmentier and Jones (2000), serial recall of locations that are specified by a sequence of sounds is prone to temporal error and is unaffected by motor suppression during retention. Experiments are reported here that show that with increased spatial uncertainty at recall (Experiment 1) and presentation (Experiment 2), spatial rather than temporal errors predominate. This is also the case when serial recall of sound-specified locations is subject to interference from a motor suppression task (Experiment 3). Contrary to Parmentier and Jones's (2000) original report, these results suggest that the memory representation for location is not necessarily amodal but is influenced by the representational requirements of the task being performed. This is consistent with recent findings that provide evidence for a distinct spatial working memory.

Anticipating the content and circumstances of skill transfer: unrealistic expectations of driver training and graduated licensing?

There is substantial evidence that driving skills improve during driver training, but the long-term safety benefit of such formal training remains unproven. Restricting the exposure of newly licensed drivers to more hazardous driving circumstances, as in graduated driver licensing (GDL) regimes, demonstrably reduces crash risk, but drivers remain at risk after the restrictions are eased. GDL and most other licensing regimes advocate increased basic training and practice, but thereafter require neither advanced training nor systematic increase in exposure to risk. This assumes that basic skills acquired during formal training will transfer positively to new and more demanding traffic circumstances. This paper reviews the theoretical basis for these assumptions and offers a way of systematically identifying the extent of transfer desired. It is concluded that there is little theoretical or empirical foundation for the supposition that what is learned during or after training will have a safety benefit in later driving.

Youthfulness, inexperience, and sleep loss: the problems young drivers face and those they pose for us.

Young inexperienced drivers are more likely to be involved in road traffic crashes than drivers who are older and more experienced. This paper argues that neither age nor inexperience are, in and of themselves, sufficient explanations of the association between age, experience, and casualty rates. The aim here is to consider what it is about inexperienced young drivers in particular that may increase crash risk. Evidence is reviewed showing differential sleep loss among different teenage groups, which may relate to recently presented evidence that young teenagers are more crash involved than drivers in their early twenties. Potential acute and chronic effects of sleep loss among teenagers and young adults are described.

Attention-memory interactions in scene perception.

The perception of natural scenes relies on the integration of pre-existing knowledge with the immediate results of attentional processing, and what can be remembered from a scene depends in turn on how that scene is perceived and understood. However, there are conflicting results in the literature as to whether people are more likely to remember those objects that are consistent with the scene or those that are not. Moreover, whether any discrepancy between the likelihood of remembering schema-consistent or schema-inconsistent objects should be attributed to the schematic effects on attention or on memory remains unclear. To address this issue, the current study attempted to directly manipulate attention allocation by requiring participants to look at (i) schema-consistent objects, (ii) schema-inconsistent objects, or (iii) to share attention equally across both. Regardless of the differential allocation of attention or object fixation, schema-consistent objects were better recalled whereas recognition was independent of schema-consistency, but depended on task instruction. These results suggest that attention is important both for remembering low-level object properties, and information whose retrieval is not supported by the currently active schema. Specific knowledge of the scenes being viewed can result in the recall of non-fixated objects, but without such knowledge attention is required to encode sufficient detail for subsequent recognition. Our results demonstrate therefore that attention is not critical for the retrieval of objects that are consistent with a scene's schematic content.

Sleep quantity, sleep difficulties and their perceived consequences in a representative sample of some 2000 British adults.

Sleep problems and sleep restriction are popular topics of discussion, but few representative data are available. We document Britain's sleep based on a nationally representative sample of 1997, 16-93 year olds, who participated in face-to-face interviews. Fifty-eight per cent of respondents reported sleep problems on one or more nights the previous week and 18% reported that the sleep they obtained was insufficient on the majority of nights. Sleep durations were longest in the youngest participants (16-24 years), who slept on average 1 h longer than the 7.04 (SD 1.55) sample average. Sleep duration showed no appreciable change beyond middle age. Men and women reported sleeping similar amounts but women reported more sleep problems. Men reported sleeping less when there were more children in their household. Workers (i.e. employees) reported sleeping less on workdays than on non-workdays, but those based at home and those not employed did not. Inability to switch off from work was related to sleep duration on non-workdays. Across all participants average sleep duration exhibited a non-monotonic association with quality of life (i.e. contribution of sleep to energy, satisfaction and success in work, home and leisure activities). Quality of life was positively associated with sleep duration, for durations up to 9 h, but negatively associated with quality of life beyond this. Comparison of our data with the US national sleep poll revealed that Britain sleeps as little or less, whereas a comparison with data reported 40 years ago revealed no statistically reliable reductions. Although we may not sleep less than four decades ago, when we report sleeping less we also tend to associate that lack of sleep with poor performance and quality of life.

Working-memory and auditory localization: demand for central resources impairs performance.

Four experiments explored possible roles for working memory in sound localization. In each experiment, the angular error of localization was assessed when performed alone, or concurrently with a working-memory task. The role of the phonological slave systems in auditory localization was ruled out by Experiments 1 and 2, while an engagement of central resources was suggested by the results of Experiment 3. Experiment 4 examined the involvement of visuo-spatial systems in auditory localization and revealed impairment of localization by the concurrent spatial working-memory task. A comparison of dual-task decrement across all four studies suggests that localization places greater demand on central than on spatial resources.

Safe and cost effective use of alteplase for the clearance of occluded central venous access devices.

PURPOSE: To determine whether cryopreserved solutions of the thrombolytic agent alteplase could be used as a safe, effective, and economically reasonable alternative to urokinase in patients presenting with occluded central venous access devices (CVADs). MATERIALS AND METHODS: Alteplase has been reported as an efficacious alternative to urokinase for treatment of occluded CVADs. However, the practicality of using alteplase as the thrombolytic of choice for this indication remained conjectural. To make this approach economically feasible, alteplase was diluted to 1 mg/mL and 2.5-mL aliquots were stored at -20 degrees C until use. A need to confirm that the cryopreserving and thawing of the reconstituted solution did not compromise the safety and efficacy reported from prior trials was recognized. A quality assessment initiative was undertaken to concurrently monitor the safety and efficacy of this approach. Patients presenting with occluded CVADs received a sufficient volume of the thawed alteplase solution to fill the occluded catheter(s). Data, including efficacy, adverse reactions, dwell time, and catheter type, were collected over a 5-month period. RESULTS: One hundred twenty-one patients accounting for 168 attempted clearances were assessable for safety and efficacy. One hundred thirty-six (81%) of the 168 catheter clearance attempts resulted in successful catheter clearance (95% confidence interval, 74% to 86%). No adverse events were reported. CONCLUSION: Cryopreserved 1-mg/mL aliquots of alteplase are safe and effective in the clearance of occluded CVADs when stored at -20 degrees C for 30 days. The ability to cryopreserve alteplase aliquots makes it an economically reasonable alternative to urokinase in the setting of CVAD occlusion.

Bronchobiliary fistula complicating oriental cholangiohepatitis.

Bronchio biliary fistula in adults is a rare event defined by the passage of bile into the bronchus and the sputum (biloptysis).Typically these lesions occur in the congenital form, as a result of thoracoabdominal trauma, or in rare instances as a result of iatrogenic injury or long-standing biliary tract disease and obstruction. In this paper, we report a novel case of a fatal bronchobiliary fistula that developed in a 67-year-old Chinese male with Oriental cholangiohepatitis. To our knowledge, this is the first case report of a bronchobiliary fistula complicating the clinical management of a patient with this disease.

Identification of poor prognostic features among patients requiring mechanical ventilation after hematopoietic stem cell transplantation.

Patients who develop respiratory failure requiring mechanical ventilation after hematopoietic stem cell transplantation (HSCT) have very high mortality. Several investigators have identified prognostic features that can be used to identify a subset of these patients who are virtually certain to die, yet these have never been prospectively assessed. The objectives of this study were to determine the accuracy of published prognostic features for mortality and to determine the survival of patients who recover from respiratory failure. A systematic review of the literature was undertaken to identify reported poor prognostic features and survival rates. The study validated the reported poor prognostic features on a prospective, multicenter inception cohort of 226 patients with respiratory failure requiring mechanical ventilation after HSCT. The main outcome measures were determination of a baseline probability of death, drawn from literature review; likelihood ratio of mortality for each prognostic feature determined from the validation cohort; conditional probability of death in the presence of each feature; and 6-month survival of those who recover. Patients requiring mechanical ventilation after HSCT have a baseline probability of death of 82% to 96%. In the setting of combined hepatic and renal dysfunction, the probability of death rises to 98% to 100%. Other previously reported prognostic features are less strongly associated with mortality. For patients who recover from respiratory failure, the proportion surviving 6 months or longer ranges from 27% to 88%. It was concluded that in patients requiring mechanical ventilation after HSCT, the presence of combined hepatic and renal dysfunction is highly predictive of death. The presence of this feature may justify the recommendation to withdraw life-sustaining measures.

Circulatory shock.

Patients with malignancy may present with acute circulatory compromise requiring ICU monitoring and care. The clinician must be familiar with a multiplicity of acute and chronic medical conditions common to the general population and also with conditions directly related to cancer or therapy thereof.

Intensive care, mechanical ventilation, dialysis, and cardiopulmonary resuscitation. Implications for the patient with cancer.

The broad range in mortality rates seen in the critically ill cancer population reflects the fact that cancer is a heterogeneous disease, affecting a heterogeneous population at different stages of care. Patients, families, and physicians frequently agonize about the utility of CPR and ICU care and whether this care should be offered. Understanding the goals of care, respecting autonomy, and knowing the likelihood of benefits and burdens of these interventions are critical in making these difficult decisions.

Accuracy of predictions of survival at admission to the intensive care unit.

PURPOSE: The purpose of this study was to compare the accuracy of outcome predictions made on the day of intensive care unit (ICU) admission by critical care physicians, critical care fellows, and primary team physicians. PATIENTS AND METHODS: Fifty-nine consecutive patients admitted to a Medical-Surgical ICU were included in the study. Two ICU attending physicians and two critical care fellows, not involved in medical management, evaluated each new ICU patient at admission and after 48 to 72 hours. Altogether six ICU attendings and six fellows were involved in the study. Each investigator separately assigned probability to each patient of being discharged alive from the ICU and the hospital. On the day of admission the primary service was also asked to estimate the likelihood of successful outcome. All values are expressed in percentiles. Statistical analysis was performed by a logistic regression procedure with a binary outcome. Data are presented as mean +/- SD. RESULTS: Fifty-nine patients were surveyed. Twenty-six (44%) patients died in the ICU, 3 (5%) died in the hospital wards, and 30 (51%) were discharged alive from the hospital. ICU attendings most reliably and accurately estimated patient outcome on admission compared with critical care fellows and primary team physicians. ICU attendings were more consistent than ICU fellows at predicting outcome at 48 and 72 hours. Clinical predictions were better for patients at the extremes of disease severity, and the accuracy of predictions in these patients was highest. Accuracy was diminished in patients with moderate compromise of clinical status. CONCLUSION: ICU attendings predicted most accurately and consistently the final outcome of patients, and ICU fellows estimated outcome more reliably than the primary service. For the most part, the primary service tended to overestimate the probability of favorable outcome of patients for whom ICU admission had been requested. Additionally, clinical accuracy of survival or mortality was best for those patients at the extremes of clinical compromise: this point seems to confirm the validity of using clinical judgement as a guide to restricting ICU resources for those severely compromised or mildly compromised.This study also indicates that predictions of outcome in critically ill patients made within days of admission are statistically valid but not sufficiently reliable to justify irrevocable clinical decisions at present.

Outcome of direct percutaneous endoscopic jejunostomy tube placement for nutritional support in critically ill, mechanically ventilated patients.

PURPOSE: Gastrointestinal function is adversely affected in critically ill mechanically ventilated patients. The most common abnormality is delayed gastric emptying. Among the options for postpyloric feeds, direct percutaneous endoscopic jejunostomy (PEJ) provides a permanent, reliable, and direct access to the small bowel and can be used for full enteral feedings, thus eliminating the need for parenteral nutrition. PATIENTS AND METHODS: All patients who underwent direct PEJ tube placement while mechanically ventilated in the intensive care unit (ICU) were evaluated. For each patient the following factors were identified: age, indication for ICU admission and PEJ placement, nutritional support before and after PEJ placement, calories received, complications, and outcome. RESULTS: Seventeen patients underwent the procedure. All had successful placement of direct PEJ tube. There was a single complication. Within 24 hours of PEJ placement, 16 of 17 patients tolerated jejunal feedings. All patients progressed to their established nutritional goals. There were no cases of aspiration of enteral feedings. In the 16 patients, total parenteral nutrition (TPN) was not required once PEJ tubes were placed. Thirteen patients were discharged home or to a rehabilitation facility with jejunal feedings. CONCLUSIONS: Direct PEJ placement is a safe and reliable device that can be successfully placed in critically ill, mechanically ventilated patients. With this procedure, all patients can meet their nutritional requirements and eliminate the need for TPN.

Transcutaneously tunneled central venous lines in cancer patients: an analysis of device-related morbidity factors based on prospective data collection.

BACKGROUND: Long-term transcutaneous tunneled central venous catheters are frequently placed in cancer patients, accounting for significant costs and morbidity. Factors influencing outcome, though, are poorly studied. METHODS: Between June 1991 and June 1993, 923 central venous tunneled catheters were placed in 791 patients at Memorial Sloan-Kettering Cancer Center. Placement-, device-, and patient-related parameters were charted prospectively (median follow-up: 120 days) and correlated to device-specific outcome events. RESULTS: Median patient age was 28.5 years (range: 0.025 - 84.5). Disease distribution included hematologic malignancies (64.7%), solid tumors (30.4%), and others (4.9%). Primary indications for line access included chemotherapy (72.8%), bone marrow transplantation (18.7%), total parenteral nutrition (6.4%), and drug administration (2.1%). There were 11 insertion complications (1.2%), including insertion failure (n = 6), hemorrhage (n = 4), and malposition (n = 1). Subsequent to placement, a proven or suspected device-specific complication occurred in 540 lines (58.5%). Per 10,000 catheter days, there were 17.6 infection episodes, 8.1 thrombotic complications, 6.9 instances of catheter breakage, 3.5 accidental or inadvertent cases of displacement, and 0.6 device leaks. Reasons for line removal or other termination of follow-up were patient's death (32.1%), treatment end (28%), infection (19.6%), suspected infection (6.3%), displacement (6.8%), thrombosis (3.1%), leak (1%), and others (3.1%). Median device-specific duration was 365 days, compared with a median complication-free device-specific duration of 167 days (P < 0.0001), reflecting a highly significant device salvage rate after complications. Catheter tip position emerged as the dominant independent prognostic factor for reduced device-specific duration or complication-free device-specific duration. CONCLUSIONS: Transcutaneous tunneled central venous lines can be placed safely, with a considerable incidence of subsequent device-specific complications, but a high salvage rate. Factors determining outcome are related to device placement, as well as the patient's disease status. In this study, patients alive 90 days after catheter placement had a 37% chance for a device complication, with a 20% chance for device loss. Future analyses of intermediate-term intravenous access should employ the measurement of device-specific outcome as a reference parameter to assess clinical results.

Ionized magnesium supplementation in critically ill patients: comparing ionized and total magnesium.

PURPOSE: The purpose of this study was to assess the effect of magnesium supplementation on total magnesium, ionized magnesium, ionized calcium, potassium, and pH in critically ill cancer patients and to compare the validity of the measurements. MATERIALS AND METHODS: Thirty-three consecutive critically ill patients receiving magnesium supplementation were placed in this prospective observational study at the Comprehensive Cancer Center, University Hospital. One gram (4.1 mmol) magnesium in 50 mL D5W was administered to critically ill patients, and the following were measured: total magnesium, ionized magnesium, ionized calcium, potassium, albumin, pH, BUN, creatinine, creatinine. RESULTS: Total magnesium and ionized magnesium increased by a mean of .11 +/- .02 and .05 +/- .01 mmol/L, respectively, after supplementation with 4.1 mmol of magnesium sulfate (P = .0001). Total magnesium, ionized magnesium, albumin, ionized calcium, potassium, and pH did not change significantly by the administration of 1 g of magnesium sulfate. CONCLUSION: The mean ionized magnesium (IMg+2) relationship to total magnesium (TMg) cannot be predicted before the supplementation with the available technology. After supplementation of 4.1 mmol/L the ionized magnesium level increased by .05 +/- .01 mmol/L. Magnesium supplementation had no significant effect on ionized calcium, potassium, and pH. TMg and IMg+2 should be followed independently.