Pregnancy-Related Allograft Rejection following Heart Transplant

Current recommendations do not discourage pregnancy in stable, orthotopic heart transplant (OHT) recipients who are more than 1 year posttransplant, although a highly specialized level of care with a multidisciplinary team is recommended. These patients may incur significant risk to themselves, their allograft, and/or their fetuses. Recognition and treatment of posttransplant complications in pregnancy also may be difficult. Although the risk of recurrent pregnancies in patients with peripartum cardiomyopathy (PPCM) is well defined, the risk of pregnancy after a PPCM patient has undergone OHT is unknown. A case of severe allograft rejection in a woman with a history of PPCM who became pregnant nearly 3 years after OHT is presented and her subsequent management is described. The data available on pregnancy after transplant are based on case reports, registry data, and reviews. The decision to become pregnant should be preceded by an extensive discussion including the patient, her partner, her obstetrician, and the transplant team, reviewing potential risks to her health as well as to her allograft and the fetus. Providers should be clear that many questions pertaining to pregnancy after transplant remain unanswered, and the patient should be comfortable going forward in this situation.

Mechanical circulatory support devices in the ICU

The medical community has used implantable mechanical circulatory support devices at increasing rates for patients dying from heart failure and cardiogenic shock. Newer-generation devices offer a more durable and compact option when compared with bulky early-generation devices. This article is a succinct introduction and overview of the hemodynamic principles and complications after device implantation for ICU clinicians. We review the concepts of device physiology, clinical pearls for perioperative management, and common medical complications after device implantation.

Implantation of the syncardia total artificial heart

With advances in technology, the use of mechanical circulatory support devices for end stage heart failure has rapidly increased. The vast majority of such patients are generally well served by left ventricular assist devices (LVADs). However, a subset of patients with late stage biventricular failure or other significant anatomic lesions are not adequately treated by isolated left ventricular mechanical support. Examples of concomitant cardiac pathology that may be better treated by resection and TAH replacement includes: post infarction ventricular septal defect, aortic root aneurysm / dissection, cardiac allograft failure, massive ventricular thrombus, refractory malignant arrhythmias (independent of filling pressures), hypertrophic / restrictive cardiomyopathy, and complex congenital heart disease. Patients often present with cardiogenic shock and multi system organ dysfunction. Excision of both ventricles and orthotopic replacement with a total artificial heart (TAH) is an effective, albeit extreme, therapy for rapid restoration of blood flow and resuscitation. Perioperative management is focused on end organ resuscitation and physical rehabilitation. In addition to the usual concerns of infection, bleeding, and thromboembolism common to all mechanically supported patients, TAH patients face unique risks with regard to renal failure and anemia. Supplementation of the abrupt decrease in brain natriuretic peptide following ventriculectomy appears to have protective renal effects. Anemia following TAH implantation can be profound and persistent. Nonetheless, the anemia is generally well tolerated and transfusion are limited to avoid HLA sensitization. Until recently, TAH patients were confined as inpatients tethered to a 500 lb pneumatic console driver. Recent introduction of a backpack sized portable driver (currently under clinical trial) has enabled patients to be discharged home and even return to work. Despite the profound presentation of these sick patients, there is a 79-87% success in bridge to transplantation.

Hunting for tularaemia - a review of cases in North Carolina

Human infections with Francisella tularensis can be acquired via numerous routes, including ingestion, inhalation, arthropod bite or direct contact with infected animals. Since 1991, there have been 25 reported cases of tularaemia in North Carolina, most of which were associated with rabbit hunting or cat bites. We present two adults cases of pulmonary and oropharyngeal tularaemia and review the reported cases since 1991-2013. We also present the fifth case of pulmonary empyema. While cavitary pneumonias are primarily treated with drainage, we illustrate a case of cavitary pneumonia associated with tularaemia successfully treated with oral ciprofloxacin after drainage. Tularaemia should be considered in patients with a perplexing radiographic image, animal exposure and lack of response to conventional empiric broad-spectrum antibiotics. Even in serious cases of pneumonic tularaemia, fluoroquinolones may provide a suitable alternative to aminoglycosides.

Safety analysis of intermittent hemodialysis in patients with continuous flow left ventricular assist devices

Dialysis centers adopt a cautious approach when it comes to performing intermittent hemodialysis (HD) on patients with continuous flow (CF) left ventricular assist devices (LVADs) because of the potential for volume flux-related complications and absence of pulsatile blood pressure for monitoring. Many patients have to remain hospitalized because of the inability of the dialysis centers to accept them for outpatient dialysis. In this study, the effect of HD was observed in such patients. Between June 2009 and October 2012, 139 patients received LVADs, of which 10 patients (7%) required intermittent HD postoperatively. The mean age of the patients was 53 ± 14 years and 90% were men. A total of 281 dialysis sessions were administered amounting to 1025 hours of dialysis. The mean systolic blood pressure monitored with Doppler device was 97 ± 18 mmHg. Dialysis durations averaged 218 ± 18 minutes. Mean blood flow rate was 334 ± 38 cc/min, and 2.6 ± 1.1 L was ultrafiltrated during each session. Only 15 (5.3%) sessions were interrupted or terminated in six patients. The reasons for termination were symptomatic hypotension--6 (2.1%), asymptomatic hypotension--3 (1%), ventricular tachycardia--1 (0.36%), dialysis machine malfunction--2 (0.7%), low phosphorus--2 (0.7%), and abdominal cramps--1 (0.36%). Volume expansion was necessary on three occasions. Low-flow device alarms were registered during two (0.71%) sessions. The results showed no serious adverse effects or deaths.

Persistent anemia after implantation of the total artificial heart

BACKGROUND

The total artificial heart (TAH) replaces the heart with 2 pneumatic pumps and 4 tilting disk mechanical valves. It was hypothesized that patients receiving TAH support have persistent hemolysis that resolves after heart transplantation (HT).

METHODS AND RESULTS

Hematocrit (HCT) was compared in patients on TAH to left ventricular assist device (LVAD) support for bridge to HT. Data were compared with t tests. The TAH (n = 36; mean age 47 ± 13 years) and LVAD patients (n = 14; mean age 53 ± 12 years) were supported for a median of 83 (interquartile range [IQR] 43-115) and 106 days (IQR 84-134), respectively. Hematocrit was similar between the TAH and LVAD patients (34 ± 6% vs 37 ± 5%; P = .07) at baseline. After placement, TAH patients had lower HCT at 2 (20 ± 2% vs 24 ± 3%), 4 (22 ± 3% vs 26 ± 3%), 6 (22 ± 4% vs 30 ± 4%), and 8 weeks (23 ± 4% vs 33 ± 5%; P < .001 for all). There were no differences in HCT at 1 (30 ± 4% vs 29 ± 7%; P = .42) and 3 months (35 ± 7% vs 35 ± 4%; P = .98) after removal of the devices for HT. TAH patients had undetectable haptoglobin in 96% of assessments, increased lactate dehydrogenase (1,128 ± 384 units/L), and detectable plasma free hemoglobin in 40% of measurements (21 ± 15 mg/dL). High sensitivity C-reactive protein (52 ± 50 mg/dL) was elevated, and reticulocyte production index was decreased (1.6 ± 0.6).

CONCLUSIONS

Patients implanted with a TAH have persistent anemia that resolves only after HT. The association of hemolysis, ineffective erythropoiesis, and inflammation with the TAH warrants further study.

Phosphodiesterase inhibitors, congestive heart failure, and sudden death: time for re-evaluation

A 42-year-old diabetic man was admitted with systolic heart failure and pulmonary hypertension being treated with sildenafil for the previous year. With an increase in creatinine, he experienced 3 episodes of ventricular tachycardia and ventricular fibrillation. Withdrawal of the phosphodiesterase (PDE) inhibitor resulted in no further episodes of dysrhythmias. The basic pharmacology of PDE inhibitors is presented and the use of PDE-3 inhibitors for the treatment of heart failure causing an increase in sudden death is also reviewed. There have been several cases of sudden death associated with sildenafil use and with its increasing use in patients with severe pulmonary hypertension and decompensated heart failure. The authors also reviewed the electrophysiologic effects of PDE-5 inhibitors associated with their use. The crossover between PDE-3 and PDE-5 inhibitors is also discussed and caution is urged when contemplating the use of PDE-5 inhibitors in patients with systolic heart failure and pulmonary hypertension.

Prognostic utility of ST2 in patients with acute dyspnea and preserved left ventricular ejection fraction

BACKGROUND

Soluble ST2 (sST2), an interleukin-1 receptor family member, is an emerging risk indicator for patients with cardiovascular disease. We evaluated the prognostic role of sST2 for patients presenting to the emergency department with acute dyspnea, with a focus on those with preserved left ventricular ejection fraction (LVEF ≥50%), as risk stratification is often most complex in this subgroup.

METHODS

We conducted a post hoc analysis of 387 patients [39% female, mean (SD) age 57.6 (14.5) years] presenting to the emergency department with dyspnea and followed for 1 year (97% complete follow-up). We examined clinical data, concentrations of serum biomarkers [sST2, amino-terminal pro-B-type natriuretic peptide (NT-proBNP)], and transthoracic echocardiography.

RESULTS

Patients had a median sST2 concentration of 38.4 U/mL [interquartile range (IQR) 25.5-64 U/mL]. Forty-six patients (12%) died during follow-up. Log sST2 [hazard ratio (HR) (95% CI) 2.85 (2.04-3.99), P < 0.001rsqb] and log NT-proBNP [1.28 (1.13-1.45), P < 0.001] concentrations were significant predictors of mortality at 1 year. After multivariate adjustment, only sST2 remained predictive of mortality [per log: 2.14 (1.37-3.38), P = 0.001]. In the subpopulation of individuals with normal systolic function (n = 200), only sST2 continued to predict mortality after multivariate adjustment [per log: 2.57 (1.12-5.91), P = 0.03]. Only NT-proBNP, but not sST2, concentrations correlated with multiple echocardiographic indices of left ventricular diastolic function.

CONCLUSIONS

sST2 is a strong predictor of mortality in patients presenting with acute dyspnea, particularly those with preserved LVEF, and may be useful for triage and risk stratification of this challenging group.

Implantable mechanical circulatory support: demystifying patients with ventricular assist devices and artificial hearts

Engineering advancements have expanded the role for mechanical circulatory support devices in the patient with heart failure. More patients with mechanical circulatory support are being discharged from the implanting institution and will be seen by clinicians outside the immediate surgical or heart-failure team. This review provides a practical understanding of device design and physiology, general troubleshooting, and limitations and complications for implantable left ventricular assist devices (pulsatile-flow and continuous-flow pumps) and the total artificial heart.

The cardioprotective effects of fish oil during pressure overload are blocked by high fat intake: role of cardiac phospholipid remodeling

Supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil may prevent development of heart failure through alterations in cardiac phospholipids that favorably impact inflammation and energy metabolism. A high-fat diet may block these effects in chronically stressed myocardium. Pathological left ventricle (LV) hypertrophy was generated by subjecting rats to pressure overload by constriction of the abdominal aorta. Animals were fed: (1) standard diet (10% of energy from fat), (2) standard diet with EPA+DHA (2.3% of energy intake as EPA+DHA), (3) high fat (60% fat); or (4) high fat with EPA+DHA. Pressure overload increased LV mass by approximately 40% in both standard and high-fat diets without fish oil. Supplementation with fish oil increased their incorporation into cardiac phospholipids, and decreased the proinflammatory fatty acid arachidonic acid and urine thromboxane B(2) with both the standard and high-fat diet. Linoleic acid and tetralinoloyl cardiolipin (an essential mitochondrial phospholipid) were decreased with pressure overload on standard diet, which was prevented by fish oil. Animals fed high-fat diet had decreased linoleic acid and tetralinoloyl cardiolipin regardless of fish oil supplementation. Fish oil limited LV hypertrophy on the standard diet, and prevented upregulation of fetal genes associated with heart failure (myosin heavy chain-beta and atrial natriuetic factor). These beneficial effects of fish oil were absent in animals on the high-fat diet. In conclusion, whereas treatment with EPA+DHA prevented tetralinoloyl cardiolipin depletion, LV hypertrophy, and abnormal genes expression with pressure overload, these effects were absent with a high-fat diet.

Natriuretic peptides and echocardiography in acute dyspnoea: implication of elevated levels with normal systolic function

AIMS

Previous evaluations of natriuretic peptide (NP) levels in patients with acute dyspnoea presenting to the emergency department (ED) have selected only a minority of patients for echocardiography. We aimed to evaluate the association between NPs and more subtle echocardiographic findings and to assess the potential for NPs to provide additional prognostic information beyond that provided by echocardiography in 'all-comers' with acute dyspnoea.

METHODS AND RESULTS

Prospective echocardiograms were performed on 338/412 patients presenting to the ED with acute dyspnoea. B-type natriuretic peptide and NT-proBNP were measured on presentation. Patients were followed-up for 1 year. Decompensated heart failure was diagnosed in 37% of patients and 13% died. The diagnostic accuracy (c-statistic) of BNP and NT-proBNP for identifying LVEF <or= 40% was 0.88 (P < 0.001) and 0.86 (P < 0.001), respectively. The c-statistics for BNP and NT-proBNP for identifying diastolic dysfunction were 0.67 (P < 0.001) and 0.67 (P < 0.001); but only 0.57 (P = 0.09) and 0.60 (P = 0.02) in patients with LVEF >or= 50%. Natriuretic peptides, but not LV mass or diastolic parameters, independently predicted mortality at 1 year in all patients and in those with an LVEF >or= 50%.

CONCLUSION

In an acute dyspnoea population with 'all-comers' undergoing echocardiography, NPs correlate strongly with structural abnormalities and identify those with preserved LVEF at highest risk for death. Careful interpretation of elevated NP values is needed in the presence of preserved systolic function.

Lack of diagnostic and prognostic utility of circulating plasma myeloperoxidase concentrations in patients presenting with dyspnea

BACKGROUND

Plasma myeloperoxidase (MPO), an inflammatory biomarker, is associated with increased mortality in patients with acute coronary syndrome or chronic left ventricular systolic dysfunction. We sought to assess the diagnostic accuracy of MPO for acute decompensated heart failure (ADHF) and its prognostic value for patients with acute dyspnea.

METHODS

In a prospective, observational study conducted in 5 US centers, 412 patients [mean (SD) age, 58 (14) years; 39% women] presenting with dyspnea to the emergency department were enrolled and followed for 1 year. Clinical, serum/plasma biomarker [MPO, B-type natriuretic peptide (BNP), N-terminal proBNP (NT-proBNP)], and transthoracic echocardiographic data were obtained.

RESULTS

We observed no differences in MPO concentration (P = 0.07) between patients with ADHF [n = 147; median, 553 pmol/L; interquartile range (IQR), 415-738 pmol/L] and those without ADHF (n = 265; median, 576 pmol/L; IQR, 413-884 pmol/L). The diagnostic accuracy for ADHF was excellent for BNP [area under the ROC curve (AUC), 0.90; P < 0.001] and NT-proBNP (AUC, 0.90; P < 0.001) but poor for MPO (AUC, 0.46; P = 0.18). MPO appeared uncorrelated with echocardiographic measures of cardiac structure or function. The observed 1-year mortality rate was 12%. MPO concentration also appeared unrelated to mortality [hazard ratio, 1.25 (above vs below the median); 95% CI, 0.71-2.18], whereas BNP (P = 0.001) and NT-proBNP (P < 0.001) were significant predictors of mortality. MPO concentration provided no prognostic information in addition to that of BNP or NT-proBNP concentration.

CONCLUSIONS

Unlike natriuretic peptides, MPO concentration was not predictive of ADHF diagnosis or 1-year mortality in a heterogeneous sample of emergency department patients with acute dyspnea.

The characteristics and prognostic importance of NT-ProBNP concentrations in critically ill patients

BACKGROUND

There are limited data for prognostic and diagnostic use of natriuretic peptides in intensive care unit (ICU) patients. We evaluate amino-terminal brain natriuretic peptide (NT-proBNP) in the medical ICU, specifically its correlation with noncardiac admission diagnosis and prognosis of critically ill patients.

METHODS

NT-proBNP (pg/mL) was measured in 179 ICU patients without acute decompensated heart failure or acute coronary syndrome. Death during hospitalization (mortality), APACHE II score, laboratory data, echocardiograms, medical history, and demographics were assessed. NT-proBNP concentrations were compared with established cutoffs for congestive heart failure (>450 pg/mL for patients <50 years of age, >900 pg/mL for patients 50-70 years of age, and >1800 pg/mL for patients >70 years of age). Predictors of mortality and of NT-proBNP were analyzed by regression analysis. Tertiles were compared by analysis of variance and chi-squared test.

RESULTS

NT-proBNP was elevated in these ICU patients (median 2139 pg/mL, 25th percentile 540 pg/mL, 75% percentile 7389 pg/mL). Severity of illness and renal dysfunction (APACHE II score and serum creatinine) increased with rising NT-proBNP. The incidence of acute respiratory distress syndrome, sepsis, death, history of coronary artery disease (CAD) or congestive heart failure (all P <.05) increased with each tertile. Independent predictors of increased NT-proBNP were creatinine (P <.001), CAD (P <.001), APACHE II score (P <.05), and sepsis (P < or =.001). Overall hospital mortality was 26%, and log NT-proBNP (P <.05), APACHE II (P < or =.001), and CAD (P <.05) were independent predictors of mortality.

CONCLUSIONS

For patients admitted to the ICU without decompensated heart failure or acute coronary syndrome, NT-proBNP concentrations are markedly elevated, especially in patients with sepsis. NT-proBNP strongly and independently predicts mortality. However, NT-proBNP should not be used to direct volume management in critically ill patients.

Amyloidosis and the heart: a comprehensive review

Infiltration of the heart from insoluble protein deposits in amyloidosis often results in restrictive cardiomyopathy that manifests late in its course with heart failure and conduction abnormalities. While the rare primary amyloidosis-related heart disease has been well characterized, senile amyloidosis occurring in the seventh decade of life most frequently affects the heart. Early diagnosis of cardiac amyloidosis may improve outcomes but requires heightened suspicion and a systematic clinical approach to evaluation. Demonstration of tissue infiltration of biopsy specimens using special stains, followed by immunohistochemical studies and genetic testing, is essential in defining the specific protein involved. The therapeutic strategy depends on the characterization of the type of amyloid protein and extent of disease and may include chemotherapy, stem cell transplantation, and liver transplantation. Heart transplantation is controversial and is generally performed only at isolated centers.

The adequacy of laboratory monitoring in patients treated with spironolactone for congestive heart failure

OBJECTIVES

This study was designed to determine the adequacy of monitoring patients receiving spironolactone as well as spironolactone's relationship to hyperkalemia.

BACKGROUND

After the Randomized Aldactone Evaluation Study (RALES) demonstrated a 30% mortality benefit for treating severe heart failure patients with spironolactone, acceptance of this drug was overwhelming. Hyperkalemia and worsening renal function were rare in RALES, but laboratory monitoring was frequent. In clinical practice, the incidence of hyperkalemia and worsening renal function and adequacy of follow-up is unknown.

METHODS

We reviewed the monitoring of congestive heart failure (CHF) patients with spironolactone initiation after publication of RALES. All potassium and creatinine determinations at baseline and within three months following therapy initiation were assessed. Increased potassium was defined as any [K] > or = 5.5 mEq/l and severe hyperkalemia as any [K] > or = 6.0.

RESULTS

A total of 840 patients had new prescriptions for spironolactone. Of these, 91% had baseline laboratory values, and 34% did not have any serum potassium or creatinine determined within three months. Patients seen in the cardiology clinic were more likely to have appropriate follow-up (p < or = 0.001). Of 551 patients with follow-up laboratory values determined, 15% developed hyperkalemia and 6% developed severe hyperkalemia. Fifty-one patients (9%) developed renal dysfunction, of whom 25 developed hyperkalemia within three months. Hyperkalemia developed in 48 of 138 (35%) patients with baseline creatinine > or = 1.5 mg/dl and 12 of 19 (63%) with baseline creatinine > or = 2.5 mg/dl.

CONCLUSIONS

Many patients treated with spironolactone for CHF do not receive needed follow-up of potassium or creatinine concentrations, although hyperkalemia and renal dysfunction are common. Elevated baseline creatinine predicts patients at high risk. Physician education of the risks of spironolactone and the need for follow-up is essential.

Current concepts for the neurohormonal management of left ventricular dysfunction after myocardial infarction

The importance of addressing neurohormonal activation in patients after a myocardial infarction is now well-appreciated. Inhibition of the renin-angiotensin-aldosterone axis and the sympathetic nervous system can result in improved cardiac function and survival. As we learn more about other systems, we should be able to realize further benefits. In particular, the roles of endothelin, matrix metalloproteinases, and cytokines in remodeling are being investigated, with the potential to result in better outcomes for patients.

Reevaluation of perioperative myocardial infarction in patients with prior myocardial infarction undergoing noncardiac operations

We studied 275 patients with prior myocardial infarctions undergoing noncardiac operations to determine the incidence and outcome of perioperative myocardial reinfarction. Perioperative myocardial reinfarction developed in 13 patients (4.7%) of whom 3 (23%) died of cardiac causes. When time between prior myocardial infarction and the date of anesthesia was analyzed, the incidence of perioperative myocardial reinfarction was 4.3% at 0-3 mo, 0 at 4-6 mo, 5.7% at greater than 6 mo, and 3.3% at an indeterminate exact interval. None of the variables analyzed showed any significant correlation with the rate of reinfarction. The urgency of operation and aortic or vascular procedures were the only variables that approached, but failed to achieve, statistical significance.

Angina and other risk factors in patients with cardiac diseases undergoing noncardiac operations

Six hundred eighty-eight consecutive patients with cardiac diseases or who were older than 70 yr of age, all of whom were undergoing noncardiac operations, were studied. Twenty-four preoperative risk factors were analyzed for the outcome of perioperative myocardial infarction (PMI) or cardiac death using stepwise logistic regression. Old age, emergency operation, angina, previous myocardial infarction, electrocardiographic signs of ischemia, type of surgical procedure, and hypokalemia were identified as individual factors useful in predicting outcome. Thirty-two patients (4.65%) developed PMI. Seven of these 32 patients (21.9%) and eight more patients without PMI--a total of 15 patients (2.2%)--died a cardiac death. Nonfatal but serious complications occurred in 23% of the patients. Patients undergoing emergency operations and patients with chronic stable angina, previous myocardial infarction, and electrocardiographic signs of ischemia were found to be at increased risk for PMI and cardiac death.

Preparation and evaluation of 99mTc-t-butylisonitrile (99mTc-TBI) for myocardial imaging: a kit for hospital radiopharmacy

A previous method was modified to obtain [99mTc(TBI)6]+ by reacting Zn(TBI)2Br2 directly with 99mTcO4- in the presence of Sn2+ ions. [Cu(TBI)4]Cl was next used as a source of TBI. On reaction with 99mTcO4- and Sn2+ ions for 3 min at 100 degrees C, [99mTc(TBI)6]+ product of radiochemical purity greater than 90% and yield greater than 70% was obtained. Data of biodistribution in rats (2-2.5% in heart) and biokinetics in rabbits were satisfactory. The kit formulation was found to be stable and also safe for administration.

Cardiac transplantation: a prospective comparison of ketamine and sufentanil for anesthetic induction

The hemodynamic effects of ketamine, 1.5 mg/kg, or sufentanil, 3.4 +/- 0.3 micrograms/kg, were studied prospectively for the anesthetic induction of 20 patients with cardiomyopathies undergoing cardiac transplantation. Plasma epinephrine (EPI), norepinephrine (NE), and sufentanil levels were also obtained. Measurements were taken at various times before induction and following intubation. Following ketamine, progressive increases (P less than 0.05) in mean arterial pressure (28%, MAP), mean pulmonary artery pressure (56%, PAP), central venous pressure (109%, CVP), and pulmonary capillary wedge pressure (84%, PCWP) occurred over time, whereas the cardiac index (CI), stroke volume index (SVI), and stroke work index (SWI) remained unchanged or decreased. The use of sufentanil was associated with no significant changes in MAP, PAP, CVP, PCWP, CI, SVI, or SWI. The heart rate (HR) did not significantly change in either group. Plasma NE significantly increased (31%) in the ketamine group, peaking at 10 minutes; whereas EPI levels did not significantly change in either group. Plasma sufentanil did not reflect the microgram/kg or microgram/BSA administered dose, suggesting individualized distribution kinetics. Since perioperative morbidity and mortality did not differ between groups, both ketamine and sufentanil are acceptable drugs for the anesthetic induction for cardiac transplantation. However, the dissimilar hemodynamic effects caused by ketamine and sufentanil suggest that this conclusion may not be applicable to the patient with a cardiomyopathy undergoing noncardiac surgery.

Multiple tamping effects on drug dissolution from capsules filled on a dosing-disk type automatic capsule filling machine

The effects of number of tamps and tamping force on drug dissolution from capsules filled on an instrumented dosing-disk automatic capsule filling machine (Hofliger-Karg) were studied using hydrochlorothiazide as a model, low dose, poorly soluble drug. Generally, there was a trend toward slower dissolution rate with increasing numbers of tamps, the effect being most marked when insoluble dicalcium phosphate dihydrate was the filler. Higher compression forces improved drug release when anhydrous lactose was the filler, but adversely affected the dicalcium phosphate-based capsules. Inclusion of 4% croscarmellose sodium disintegrant tended to nullify the effects of number of tamps or tamping force with both fillers; however, the disintegrant also markedly enhanced drug dissolution from the dicalcium phosphate-based formulation. Hydrochlorothiazide dissolution from the latter formulation without disintegrant appeared to follow a "diffusion from insoluble matrix" model regardless of number of tamps or their intensity. Mercury intrusion pore size distribution data for some plugs suggested that for tamps of equal force (100 or 200 N), further powder consolidation after two tamps does not occur.

An investigation of some factors influencing plug formation and fill weight in a dosing disk-type automatic capsule-filling machine

The progressive formation of plugs resulting from successive tamps in a dosing disk-type automatic capsule-filling machine was investigated for three fillers: anhydrous lactose, dicalcium phosphate, and microcrystalline cellulose. An evaluation of seven compaction parameters revealed that all tamping stations and all piston positions within a station, with the exception of station #1, contribute equally to plug formation. Model calculations suggesting that fill weight could be achieved in only three tamps were supported by direct experimental observation. The effective available fill volume was shown to be greater than the nominal volume of the dosing disk cavity. This was verified by using a modified scrape-off at station #5, which eliminated the powder head over the disk at that station. Here, increases in tamping force resulted in harder plugs, as measured with an improved plug mechanical strength tester, with fill weights remaining unchanged. However, plug segments did not increase in mechanical strength when additional segments were compressed over them using the same force. For one excipient (microcrystalline cellulose), the fill weights and the mechanical strengths of systems containing 0, 0.10, 0.25, and 0.50% magnesium stearate were measured. The 0.10% level was found to be optimum in that it resulted in maximum plug mechanical strengths and fill weights, regardless of the number of tamps used and/or their intensity.

A review of pulmonary artery catheterization in 6,245 patients

From July 1977 to December 1982, 6,245 patients requiring cardiac and noncardiac operations had pulmonary artery (PA) catheterizations for perioperative monitoring. Their ages ranged from 4 to 94 years. PA catheters were inserted through the external or internal jugular vein in 6,146 patients, while arm veins were used in 99 patients. Complications included persistent PVCs requiring therapy in 193 (3.1%), right bundle branch blocks in three (0.048%), left bundle branch and complete heart block each in one patient (0.016%), intrapulmonary hemorrhage in four (0.064%), minor pulmonary infarcts in four (0.064%), perforation of right ventricle in one (0.016%), and death from uncontrollable pulmonary hemorrhage in one patient (0.016%). This investigation reveals a low incidence of morbidity associated with PA catheterization.

Solid-phase radioimmunoassay for human placental lactogen in serum

We report a solid-phase radioimmunoassay for human placental lactogen, in which antibody-coated polystyrene tubes and polyurethane sponges are used. Incubation time and temperature, ionic strength of buffer, and nonspecific adsorption have been evaluated for optimum conditions required for routine clinical assays. The validity of the assay technique has been ascertained by its specificity, reproducibility, and recovery. The sensitivity of this method is 0.4 ng of placental lactogen per assay tube.

Solid-phase radioimmunoassay for human placental lactogen in serum

We report a solid-phase radioimmunoassay for human placental lactogen, in which antibody-coated polystyrene tubes and polyurethane sponges are used. Incubation time and temperature, ionic strength of buffer, and nonspecific adsorption have been evaluated for optimum conditions required for routine clinical assays. The validity of the assay technique has been ascertained by its specificity, reproducibility, and recovery. The sensitivity of this method is 0.4 ng of placental lactogen per assay tube.