The essentials of calcium, magnesium and phosphate metabolism: part I. Physiology.

OBJECTIVE: To review the components of calcium, phosphate and magnesium metabolism that are relevant to the critically ill patient in a two-part presentation. DATA SOURCES: A review of articles reported on calcium, phosphate and magnesium disorders in the critically ill patient. SUMMARY OF REVIEW: Calcium, phosphate and magnesium have important intracellular and extracellular functions with their metabolism often linked through common hormonal signals. A predominant portion of total body calcium is unionised within bone and serves an important structural function. Intracellular and extracellular ionised calcium changes are often linked and have important secretory and excitatory roles. The extracellular ionised calcium is carefully regulated by parathyroid hormone and vitamin D, whereas calcitonin is secreted largely in response to hypercalcaemia. Phosphorous is needed for bone structure although it also has an important role in cell wall structure, energy storage as ATP, oxygen transport and acid-base balance. Ionised calcium, in as far as it controls PTH secretion, indirectly controls urinary phosphate excretion. When plasma phosphate increases, tubular reabsorption also increases up to a maximum (TmPO4), thereafter phosphate is excreted. The minimum oral requirement for phosphate is about 20 mmol/day. Magnesium is a predominantly intracellular ion that acts as a metallo-coenzyme in more than 300 phosphate transfer reactions and thus has a critical role in the transfer, storage and utilisation of energy within the body. Extracellular magnesium concentrations are largely controlled by the kidneys with the renal tubular maximum reabsorption (TmMg) controlling the plasma magnesium concentration. CONCLUSIONS: In the critically ill patient calcium, magnesium and phosphate metabolism, are often disturbed with an alteration in intake, increased liberation from bone and damaged tissue and reduced excretion (e.g. during renal failure), causing alterations in extracellular concentrations and subsequent disordered organ function.

The essentials of calcium, magnesium and phosphate metabolism: part II. Disorders.

OBJECTIVE: To review the components of calcium, phosphate and magnesium metabolism that are relevant to the critically ill patient, in a two-part presentation. DATA SOURCES: A review of articles reported on calcium, phosphate and magnesium disorders in the critically ill patient. SUMMARY OF REVIEW: Abnormal calcium metabolism in the critically ill patient often presents with an alteration in plasma ionised calcium. The characteristic clinical features of an acute reduction in ionised plasma calcium include tetany, laryngospasm, paraesthesia, confusion, hallucinations, seizures and, rarely, hypotension all of which resolve with intravenous calcium administration. The clinical features of an acute increase in plasma ionised calcium include anorexia, nausea, vomiting, constipation, polyuria, weakness, lethargy, hypotonia and ectopic calcification and, depending on the aetiology, may require intravenous saline, frusemide, diphosphonate, glucocorticoid or calcitonin. Acute hypophosphataemia may present with paraesthasia, confusion, seizures, weakness, hypotension and heart failure and in the critically ill requires intravenous sodium or potassium phosphate. Hyperphosphataemia is often associated with renal failure and if severe usually presents with the clinical features of the associated hypocalcaemia. The clinical features of hypomagnesaemia include confusion, delerium, seizures, weakness, cramps, tetany and tachyarrhythmias, all of which resolve with intravenous magnesium sulphate. Hypermagnesaemia is usually associated with excess magnesium administration in a patient with renal failure and if severe can cause areflexia, hypotonia, respiratory and cardiac arrest. Intravenous calcium chloride will rapidly reverse the cardiovascular abnormalities. CONCLUSIONS: Calcium, phosphate and magnesium functions are closely linked with abnormal plasma levels of these compounds often causing similar cardiovascular and neurological features.

Taking account of quality. Discussion.

Another report from the Institute of Medicine in March 2001 has joined a large body of literature documenting serious quality and safety problems. Eight health care leaders discuss ways in which organizations can reduce medical errors and improve patient outcomes.

Juvenile gigantomastia: presentation of four cases and review of the literature.

Juvenile gigantomastia is a benign disorder of the breast in which one or both of the breasts undergo a massive increase in size during adolescence. The authors present a series of four cases of juvenile gigantomastia, advances in endocrine management, and the results of surgical therapy. Three patients were treated for initial management of juvenile gigantomastia and one patient was evaluated for a gestationally induced recurrence of juvenile gigantomastia. The three women who presented for initial management had a complete evaluation to rule out other etiologies of breast enlargement. Endocrine therapy was used in 2 patients, one successfully. A 17-year-old girl had unilateral hypertrophy treated with reduction surgery. She had no recurrence and did not require additional surgery. Two patients, ages 10 and 12 years, were treated at a young age with reduction mammaplasty, and both of these girls required secondary surgery for treatment. One patient underwent subtotal mastectomy with implant reconstruction but required two subsequent operations for removal of recurrent hypertrophic breast tissue. The second patient started a course of tamoxifen followed by reduction surgery. While on tamoxifen, the second postoperative result remained stable, and the contralateral breast, which had exhibited some minor hypertrophy, regressed in size. The fourth patient was a gravid 24-year-old who had been treated for juvenile gigantomastia at age 14, and presented with gestationally induced recurrent hypertrophy. The authors' experience has been that juvenile gigantomastia in young patients is prone to recurrence, and is in agreement with previous studies that subcutaneous mastectomy provides definitive treatment. However, tamoxifen may be a useful adjunct and may allow stable results when combined with reduction mammaplasty. If successful, the use of tamoxifen would eliminate the potential complications of breast prostheses. Lastly, the 17-year-old patient did not require secondary surgery, suggesting that older patients may be treated definitively with reduction surgery alone.

Brain abscess as a complication of orthognathic surgery: diagnosis, management, and pathophysiology.

We present what we believe is the first case of a brain abscess resulting from orthognathic surgery reported in the literature. Although recent advances have significantly improved the treatment of brain abscesses, delays in diagnosis lead to persistent high rates of mortality. Often, the initial symptoms are vague and nonspecific. Commonly, the neurologic status of the patient deteriorates significantly before suspicion is raised and a CT scan is obtained. This case report is intended to benefit all practitioners who participate in the perioperative care of orthognathic surgery patients. Although the occurrence of a brain abscess is rare, it is hoped that this case will heighten the awareness of clinicians to this potential complication.

Using nursing diagnoses and interventions in an inpatient amputee program.

The purpose of this study was to provide a descriptive analysis of an inpatient amputee program at Spaulding Rehabilitation Hospital (SRH) in Boston; the analysis focused on nursing diagnoses and interventions documented in the medical record. The study was based on a retrospective chart review conducted for 96 inpatient lower-extremity amputees who were admitted from October 1988 through September 1989. The results of the study identified common nursing diagnoses and interventions used for a medically complex population of people who had had amputations. In addition, the study showed that most subjects improved in functional status, thus confirming the success of the program. All subjects were either discharged to their homes or transferred to an acute care facility. The study results will be used to develop a standardized nursing care plan, as well as creative new modalities for patient and family education, at SRH.

A diabetes control program in a public health care setting.

The Houston Diabetes Control Program is part of an effort by the State of Texas and approximately 30 other programs throughout the United States to ensure that persons with diabetes-related complications receive ongoing state-of-the-art preventive care and treatment. For the past 5 years, this program has served an urban, high-risk patient population with special cultural, ethnic, and economic challenges. The intervention has included the development and implementation of protocols for the prevention and care of diabetes-related complications of the eyes, lower extremities, and cardiovascular system, as well as general management of diabetes and patient and professional education. The program is ongoing in nine community health centers located in low-income neighborhoods of a large metropolitan area. The results thus far indicate an increase in sensitive eye examinations from 8 percent to 26 percent of the patient population, a reduction in incidence of legal blindness from 9.5 to 2.7 per 1,000 during a 4-year period, an increase in foot examinations from 18 percent to 44 percent of the patient population, and 77 percent of hypertensive patients in good control of blood pressure at less than 160 over 95 mmHg (millimeters of mercury). On the average, there have not been significant long-term improvements in weight reduction or blood glucose control. The major challenges for this program are (a) improvement in control of glycemia, hypertension, and cholesterol; (b) more effective diet and physical activity interventions; and (c) more effective education approaches that help patients to understand metabolic and cardiovascular functions. These challenges will require collaboration of health care professionals in constructive and imaginative ways through their unselfish commitment toward common goals.

Empowerment through rehabilitation nursing certification.

Certification empowers nurses by validating their clinical competency and continued professional growth. This article discusses the current state of certification in the nursing profession. The potential benefits to the certified nurse and the costs in both time and money needed to achieve and maintain certification are addressed. The article also describes how the nursing department of a 284-bed rehabilitation hospital developed a program to promote specialty certification among its nursing staff. The process and outcome of this program revealed several potential research topics.

Helping female adolescents prepare to cope with irrational thinking via preventive cognitive self-instruction training.

Used Meichenbaum's (1977) cognitive self-instruction ideas to prepare a primary prevention program designed to help recipients prepare to cope with irrational thinking. Female adolescents attending a boarding school and who volunteered to participate were assigned randomly to a group instruction and a self-instruction condition. On measures of knowledge about cognitive self-instruction and confidence in the mode of presentation, the group condition seemed superior. Four members of the group condition took advantage of an offer for individual counseling while none of those in the self-instructional condition referred themselves.

Pneumococcal bacterial tracheitis.

Bacterial tracheitis is an uncommon cause of acute respiratory distress in children. The authors present a case of bacterial tracheitis in a 6-year-old girl caused by an unusual pathogen, Streptococcus pneumoniae. Her clinical presentation and radiographic findings are typical for an older child. Management of this case involved endotracheal intubation, although a review of the literature suggests that airway management can vary with age and size of the tracheal lumen. The microbiology of bacterial tracheitis shows a predominance of Staphylococcus and Streptococcus reported previously, with only three prior reported cases of Pneumococcus.

Propofol: effective dose and induction characteristics in unpremedicated children.

The induction dose, induction characteristics, and cardiovascular and respiratory effects of propofol were studied in 90 unpremedicated children 3-12 yr old. Propofol in a dose of 1-3 mg.kg-1 was injected in an antecubital vein over 10-30 s. Successful induction was defined by loss of eyelash reflex occurring within 50 s of the conclusion of propofol injection and followed by subsequent acceptance of face mask without excessive movement. The effective dose of propofol resulting in loss of eyelash reflex in 50% (ED50) and 95% (ED95) of children were 1.3 (1.1-1.4) and 2.0 (1.7-2.6) mg.kg-1 (95% confidence interval). The corresponding ED50 and ED95 for a successful induction that included acceptance of face mask were 1.5 (1.3-1.7) and 2.3 (2.1-3.0), respectively. There was a 6.6% incidence of mild to moderate pain on injection and a 12.7% incidence of involuntary movement. Apnea (cessation of breathing greater than 20 s) was seen in 21% of patients. Blood pressure decreased by more than 20% of baseline value in 48% of patients who received halothane (1-3%) after the bolus injection of propofol. It is concluded that propofol is an effective induction agent in children. A dose of 2.5-3.0 mg.kg-1 is recommended to ensure a smooth transition to an inhalational maintenance technique. The use of antecubital veins is associated with a low incidence of pain on injection.

Arousal and cardiopulmonary responses to hyperoxic hypercapnia in lambs.

Experiments were done to investigate the arousal and cardiopulmonary responses to hyperoxic hypercapnia in 8 lambs. Each lamb was anaesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms and measurements of arterial blood pressure and haemoglobin oxygen saturation. No sooner than 3 days after surgery, measurements were made in quiet sleep and active sleep during control periods when the animal was breathing 21% oxygen and during experimental periods of hyperoxic hypercapnia when the animal was breathing 10% carbon dioxide and 30% oxygen. Hyperoxic hypercapnia was terminated during each epoch by returning the inspired gas mixture to 21% oxygen once the animal aroused from sleep. Arousal occurred from both sleep states during hyperoxic hypercapnia but was delayed in active sleep compared to quiet sleep (active sleep 58 +/- 17 s; quiet sleep 21 +/- 10 s; mean +/- 1SD). There were no significant changes in heart rate or blood pressure during hyperoxic hypercapnia before arousal. However, respiratory rate and diaphragm electrical activity did increase during hyperoxic hypercapnia before arousal. Thus, our data provide evidence that hypercapnia can initiate arousal from sleep in young lambs. The mechanisms responsible for this response are yet to be determined.

Heart rate response to arousal and lung inflation following upper airway obstruction in lambs.

Experiments were done to determine the influence of arousal from sleep and lung inflation on heart rate following upper airway obstruction in lambs. Ten lambs were anesthetized and instrumented for recordings of electrocorticogram, electro-oculogram, nuchal and diaphragm electromyograms, and measurements of systemic arterial blood pressure and arterial hemoglobin oxygen saturation (fiberoptic catheter oximeter). A tracheotomy was done and a fenestrated tracheostomy tube was placed in the trachea. A 5F balloon-tipped catheter was inserted into the tube so that the airway could be obstructed by inflating the balloon. No sooner than 3 days after surgery, measurements were made during a control period of normal tidal respiration, during upper airway obstruction immediately before arousal, during upper airway obstruction immediately after arousal, and following the first lung inflation. A total of 39 epochs of quiet sleep and 33 epochs of active sleep were obtained. Heart rate and oxygen saturation decreased (p less than 0.05) during upper airway obstruction in quiet sleep and active sleep. Arousal from sleep did not significantly alter heart rate during continued upper airway obstruction. However, heart rate quickly returned toward control levels following the first lung inflation despite continued oxygen desaturation. These results provide evidence that the abrupt tachycardia following an apneic episode is related to lung inflation rather than to the arousal response per se.

Arousal from sleep during rapidly developing hypoxemia in lambs.

Arousal is an important protective response that may prevent severe hypoxemia and death during sleep. However, very little is known about arousal from sleep in response to respiratory stimuli in newborns. Experiments were therefore done to investigate the arousal response from sleep to rapidly developing hypoxemia in eight lambs. Each lamb was anesthetized and instrumented for recordings of electrocorticogram, electrooculogram, nuchal and diaphragm electromyograms, and measurements of arterial hemoglobin oxygen saturation. A tracheotomy was done and a tracheostomy tube placed in the trachea so that the fraction of inspired oxygen could be changed quickly. No sooner than 3 days after surgery, measurements were made in quiet sleep and active sleep (AS) during 30-s control periods when the animals were breathing 21% oxygen and during experimental periods of hypoxemia when the animals were breathing either 10, 5, or 0% oxygen in nitrogen. During quiet sleep, arousal occurred at similar arterial hemoglobin oxygen saturations (81 +/- 6% on 10% O2, 80 +/- 5% on 5% O2 and 83 +/- 5% on 0% O2) suggesting that arousal was independent of the rate of change of arterial oxygen. However, during AS arousal occurred at different arterial hemoglobin oxygen saturations (76 +/- 6% on 10% O2, 55 +/- 11% on 5% O2, and 44 +/- 17% on 0% O2) suggesting that arousal was dependent on the rate of change of arterial oxygen. During some epochs of AS, electrocortical signs of cerebral hypoxia and primary apnea occurred before arousal. These data provide evidence that arousal from quiet sleep in response to hypoxemia occurs once an arousal threshold has been reached.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of sarcoidosis in the Isle of Man--1: A case controlled study.

A case controlled study of 96 cases of sarcoidosis has been carried out in the Isle of Man. Age and sex matched controls were selected at random from the pathology and radiology records, which cover 85% of the resident population, and a second control group was drawn from a tuberculosis register. Special efforts were made to achieve a high level of ascertainment. In this study most cases occurred in young adults. It affected the sexes equally and occurred more frequently in the indigenous Manx population. Thirty eight cases (39.6%) had been in contact with the disease before diagnosis, compared with two (1.2%) of the combined controls. These contacts included members of the same household, colleagues at work, and close friends. A bias may have been introduced as patients would inevitably be more aware of the disease and be more likely to mention previous contact than the controls. Nevertheless, the evidence is considered to support the view that sarcoidosis is a communicable disease.

Epidemiology of sarcoidosis in the Isle of Man--2: Evidence for space-time clustering.

The case-control test for space-time clustering developed by Pike and Smith was applied to 96 cases of sarcoidosis diagnosed in the Isle of Man from 1962 to 1983. There were significantly more links between cases separated by time intervals of less than 10 years and distances of less than 100 metres than between the others. Analysis of the type of links indicated that clusters consisted of pairs whose contact was by place of residence or work. More linked cases were diagnosed less than three years apart than would be expected by chance. These findings lend support to the idea that sarcoidosis is a communicable disease.

Invasive aspergillosis in children.

Aspergillosis may complicate the course of the child in an immunocompromised state. When sinus or pulmonary infections present in immunocompromised children, one third of these patients are diagnosed accurately premortem as resulting from aspergillosis and two thirds remain undiagnosed. Mortality remains quite high, despite prompt treatment. Four children in our hospital during the last 4 years have had invasive aspergillosis presenting other than sinus or pulmonary infections. Each presented with extensive soft tissue infection. Three presented after traumatic devascularizing injuries to the leg in which massive soil and fecal contamination occurred. One child presented with absolute neutropenia secondary to treatment of acute lymphocytic leukemia. The child had a chest wall lesion develop at the site of an EKG electrode. All patients had a punctate black skin lesion with a halo of intense erythema surrounded by a zone of blanching. These lesions rapidly expanded. Initial extensive debridement of the lesions, combined with systemic chemotherapy with amphotericin B failed to halt the progression of the disease. Histology showed vascular invasion with hyphal forms. Each patient then responded well to radical debridement (three hemipelvectomies and one chest well resection). The child in an immunocompromised state who develops a red papule, then a black eschar with surrounding erythema, should have immediate biopsy that can easily demonstrate the characteristic hyphal forms. Early radical surgical debridement and antifungal therapy can be lifesaving. The initial debridement should include tissues well beyond any apparent involvement.

Effects of hyperoxia on the arousal response to upper airway obstruction in lambs.

Experiments were done to investigate the effects of increased inspired oxygen on the arousal response from sleep to upper airway obstruction in 10 newborn lambs. Each lamb was anesthetized and instrumented for recordings of electrocorticograms, electrooculogram, nuchal and diaphragm electromyograms, and measurements of systemic arterial blood pressure and oxygen saturation (fiberoptic catheter oximeter). A tracheotomy was performed and a fenestrated tracheostomy tube was placed in the trachea. A 5F balloon tipped catheter was inserted into the tube so that airflow could be obstructed by inflating the balloon. No sooner than 3 days after surgery, measurements were made during a control period and during an experimental period of upper airway obstruction; the inspired oxygen fraction was alternated hourly between 0.21 and 0.60. A total of 57 epochs of quiet sleep and 58 epochs of active sleep was obtained in eight lambs. Arousal was significantly delayed (p less than 0.005) during active sleep (21 +/- 6 s; mean +/- 1 SD) compared to quiet sleep (7 +/- 2 s) in room air. Increased inspired oxygen significantly delayed arousal (p less than 0.05) during active sleep (47 +/- 25 s), but had little effect on arousal in quiet sleep (10 +/- 4 s). These results provide evidence that arousal from active sleep following upper airway obstruction in lambs is primarily initiated by a decrease in arterial oxygen. However, arousal from quiet sleep following upper airway obstruction in lambs appears to be initiated by other stimuli.