Adrenal crisis in active duty service members

Primary adrenal insufficiency is a chronic, debilitating condition that usually produces a variety of characteristic but non-specific clinical features. Up to 25% of patients present instead with acute life-threatening adrenal crisis, marked by severe hypotension and shock. Recognition of the disease in the chronic indolent phase is critical because adrenal steroid replacement effectively relieves symptoms and prevents the development of most acute crises. To illustrate these points, we describe four case histories in which the manifestations of chronic adrenal insufficiency went unrecognized in active duty service members until they presented with near-fatal adrenal crises. The salient clinical features, diagnosis, and treatment of the disease are also reviewed.

Increased nitric oxide production in hypotensive hemodialysis patients

A subset of patients on long-term hemodialysis have sustained hypotension, defined as a predialysis systolic pressure of < 100 mmHg. To determine the role of nitric oxide (NO), an important vasodilator, in this condition, the authors measured the plasma levels of nitrite (NO2-) and nitrate (NO3-), the known NO metabolites taken as an index of NO production, in 10 hypotensive patients on long-term hemodialysis. None of them had diabetes, cirrhosis of the liver, congestive heart failure, or infection. Fifteen age and gender-matched normotensive patients on hemodialysis were selected as control subjects. Measurements of plasma levels of nitrite and nitrate based on the Greiss reaction were made. There was no significant difference in hematocrit, serum intact parathyroid hormone, total calcium, inorganic phosphorus, albumin, heart rate, cardiac index, or interdialysis weight gain between these two groups. Plasma nitrite and nitrate levels did not correlate with either predialysis serum creatinine or blood urea nitrogen. The mean arterial pressure (MAP) was significantly lower and plasma nitrite and nitrate levels were significantly higher in chronic hypotensive patients than in normotensive patients (MAP: 68.30 +/- 3.24 mmHg vs 95.20 +/- 2.44 mmHg, p < 0.001; plasma nitrite and nitrate: 72.49 +/- 14.41 mumol/L vs 36.42 +/- 5.45 mumol/L, p < 0.05). In addition, MAP from hypotensive and normotensive patients on hemodialysis was inversely correlated with plasma levels of nitrite and nitrate (r = -0.54, p < 0.01). It was concluded that enhanced NO production in this subset of patients on hemodialysis may contribute to their chronic hypotension.

Two cases of maternal antenatal splenic rupture and hypotension associated with Moebius syndrome and cerebral palsy in offspring. Further evidence for a utero placental vascular aetiology for the Moebius syndrome and some cases of cerebral palsy

We wish to report two cases of congenital abnormality after antenatal car accidents resulting in ruptured spleen and severe hypotension in the mothers at 8 and 14 weeks gestation. The first case had the classical Moebius syndrome with 6th and 7th cranial nerve palsy with abnormal brain stem evoked responses, presumably due to hypoxic/ischaemic brain stem damage and the second case had severe retardation and hypertonic cerebral palsy which at post mortem was found to be due to old hypoxic/ischaemic lesions to the caudate nucleus putamen and striatum.

CONCLUSION

The cases described provide evidence that severe maternal hypotension during pregnancy can be associated with lesions to the midbrain and brain stem of offspring. The mechanism is probably utero-placental insufficiency, and extrapolation from these two unusual cases would support utero-placental insufficiency as a cause of Moebius syndrome and limb deficiency after chorionic villus sampling.

Increased production of nitric oxide in patients with hemorrhagic fever with renal syndrome--relation to arterial hypotension and tumor necrosis factor

In 15 consecutive subjects hospitalized with nephropathia epidemica, a European form of hemorrhagic fever with renal syndrome, the plasma concentrations of nitrate plus nitrite, stable metabolites of nitric oxide, were determined. From day 3 of onset of disease the concentrations increased, peak levels being reached on days 5 to 7. Maximal plasma concentrations of nitrate plus nitrite were correlated to the degree of hypotension (r = -0.64, p = 0.02) and levels of tumor necrosis factor (TNF)-alpha (r = 0.51, p = 0.05) and soluble TNF receptors p55 and p75 (r = 0.58, p = 0.03 and r = 0.54, p = 0.04, respectively) but not to levels of interferon-gamma or interleukin-10 (p > 0.05). The results are compatible with the well-known capacity of TNF-alpha to enhance production of nitric oxide, and suggest that nitric oxide may be of physiologic importance in hemorrhagic fever with renal syndrome.

Complications of endotracheal intubation in mechanically ventilated patients in a general intensive care unit

During a period of one year, 126 patients were prospectively audited to analyse complications of endotracheal intubation in a general intensive care unit setting. A total of 62 complications were observed in 48 patients. The most frequent complications during intubation were hypotension and bradycardia. The blockage of endotracheal tubes significantly increased with the duration of intubation. Sore throat was the commonest (22%) complication following extubation. Other complications like stridor and ulceration of mouth and lips which followed extubation were not related to the duration of intubation.

The effect of arteriovenous malformations on the distribution of intracerebral arterial pressures

PURPOSE

To examine the distribution of arterial hypotension surrounding arteriovenous malformations (AVMs) using a standardized system of vascular zones.

METHODS

Mean arterial pressures were recorded during superselective cerebral angiography in 96 patients with AVMs (before they underwent liquid polymer embolization) with the use of a system of vascular zones: E = extracranial internal carotid or vertebral artery; I = intracranial internal carotid or basilar artery; T = transcranial Doppler insonation site (A1, P1, M1); H = halfway to feeder, perfusing normal tissue and shunt; and F = feeder at site of N-butyl cyanoacrylate injection. Distal arterial pressure was measured contralateral to the AVM in an additional 12 patients (zone Hc).

RESULTS

Zone pressures (mm Hg +/- SD) were E = 76 +/- 16, I = 69 +/- 15, T = 59 +/- 16, H = 47 +/- 13, and F = 39 +/- 15 mm Hg. Vessel/systemic ratios for the zones were E = 0.97 +/- 0.05, I = 0.86 +/- 0.08, T = 0.75 +/- 0.12, H = 0.61 +/- 0.13, and F = 0.50 +/- 0.18. Measurements were obtained in 29 patients in all five zones and all had similar mean values. Zone Hc pressure was 66 +/- 17 mm Hg and the ratio was 0.78 +/- 0.12, both greater than zone H values.

CONCLUSION

Using a standardized system of anatomic vascular zones, we found a progressive and significant decrease in intracerebral arterial pressure in patients with AVMs that proceeded from the circle of Willis to the nidus. Large areas of parenchyma sharing the same parent arterial supply may be subject to chronic hypotension.

Complications of mechanical ventilation. A bedside approach

Instead of cataloging complications reported to occur during mechanical ventilation, the authors have discussed the potential causes for several common scenarios in the management of ventilated patients. These include the new development of hypotension, acute respiratory distress (fighting the ventilator), repeated sounding of the ventilator's high-pressure alarm, hypoxemia, blood from the endotracheal tube, and the problem of diagnosing VAP. In the course of considering likely explanations for this group of circumstances for which the clinician is consulted or called to the bedside, virtually all reported ventilator-associated complications must be discussed. This new approach to an important aspect of ICU care may aid in clinical problem-solving and reduce the likelihood that a diagnosis will be missed or inappropriate measures taken in the absence of a systematic, pathophysiology-based approach.

[Treatment by angiotensin converting enzyme inhibitors after myocardial infarction. What did the clinical trials teach us?]

Most clinical trials of angiotensin converting enzyme inhibitors after myocardial infarction have shown an improved outcome with reduction of morbidity and mortality. In comparable groups of patients, the results are concordant with a decrease in mortality which is all the more significant and early in severe infarction with serious haemodynamic consequences. The clinician has a new arm in his therapeutic arsenal either for use in the acute phase of all cases of myocardial infarction but for only a short period of 4 to 6 weeks after which the treatment is withdrawn when the anatomical sequellae are more moderate, or for use in selected cases for longer periods (patients with severe infarction with cardiac failure and/or severe left ventricular dysfunction). The second attitude has the advantage of treating a selected population which will derive greater benefits. In all cases, treatment should be started orally at low doses, and the dose must be increased rapidly do attain the target dosage under close clinical and biological surveillance. When the classical contraindications are respected, ACE inhibitors seem to be well tolerated even at the relatively high dosages recommended after myocardial infarction. Hypotension and, more rarely, renal failure, are the two most common complications leading to withdrawal of treatment, but neither of these side effects was associated with increased mortality in any of the clinical trials. The mechanisms by which ACE inhibitors exert these beneficial effects after myocardial infarction are not only their haemodynamic effects and their role in ventricular remodelling, but also probably by a vascular protective action which, if confirmed, would further increase the indications of this therapeutic class in cardiovascular diseases.

Liver hemorrhage during laparotomy in patients with necrotizing enterocolitis

Major liver hemorrhage (LH) without obvious iatrogenic injury was recently observed in several patients during operation for necrotizing enterocolitis (NEC). The purpose of this study was to determine the incidence and risk factors associated with the development of LH in patients with NEC.

METHODS

The hospital charts of patients with NEC who underwent surgical exploration during a 5-year period (1989-1994) were reviewed. The patients in whom LH developed without obvious significant iatrogenic liver injury were compared with those who did not have LH.

RESULTS

Eight of the 68 patients reviewed had LH. The survival rate for those with LH was 13%, compared with 88% for those without LH (P < .001). The patients with LH had a younger gestational age (28 +/- 3 weeks v 32 +/- 5 weeks) and a lower birth weight (1,262 +/- 489 g v 1,649 +/- 666 g); however, the differences were not significant. The patients with LH had significantly lower preoperative mean arterial blood pressure (35 +/- 1 mm Hg v 46 +/- 3 mm Hg; P < .001) and required greater fluid intake (272 +/- 28 mL/kg/d v 186 +/- 9 mL/kg/d; P < .01) for the 24 hours preceding surgery.

CONCLUSION

LH is as an important and lethal complication associated with laparotomy in very small infants with NEC. The presence of hypotension and the administration of large amounts of volume in the preoperative period appear to be risk factors. Earlier surgical intervention and restoration of blood pressure using inotropic agents, once a particular level of fluid administration has been achieved, my be preventive.

Effect of a new model of hemodialysis potassium removal on the control of ventricular arrhythmias

The primary aim of this multicenter, prospective, randomized cross-over study was to clarify whether a new model of hemodialysis (HD) potassium (K) removal using a decreasing intra-HD dialysate K concentration and a constant plasma-dialysate K gradient (treatment B) is capable of reducing the arrhythmogenic effect of standard HD, which has a constant dialysate K concentration and decreasing plasma-dialysate K gradient (treatment A). The secondary aim was to verify whether this new model is clinically safe. In treatment B, the initial dialysate K concentration had to be 1.5 mEq/liter less than the plasma K concentration, and exponentially decrease to 2.5 mEq/liter at the end of HD. Forty-two chronic HD patients with an increase in premature ventricular complexes (PVC) during dialysis were enrolled from 18 participating centers, and randomly assigned to either sequence 1 (ABA) or sequence 2 (BAB). A pool of 333 of 378 expected ECG Holter recordings were checked for signal quality; 269 (71%) from 36 patients (86%) had a satisfactory signal quality and 108 were selected for analysis (1 per patient per period). There was a difference in the natural logarithm of the increase in PVC/hr and PVC couplets/hr during HD between treatments A and B (1.70 +/- 1.59 vs. 1.09 +/- 1.76 and 0.94 +/- 0.86 vs. 0.64 +/- 1.01, a reduction of 36% and 32%, P = 0.011 and 0.047, respectively) without any carry over effect (P = 0.61 and 0.24, respectively). The fact that this decrease of one third is due to a lower plasma-dialysate K gradient is supported by the observation that it was more evident during the first than the last two hours of HD (a reduction in the natural logarithm of the increase in PVC/hr and PVC couplets/hr of 60% and 60%, P 0.002 and 0.009, vs. 26% and 17%, P = 0.098 and 0.332, respectively): the initial plasma-dialysate K gradient was 2.3 times lower during treatment B than during treatment A, without adversely affecting pre-HD plasma K levels. These results could have a considerably clinical impact not only because of the possibility of physiologically decreasing the arrhythmogenic effect of HD, but also because this effect can be considered a "marker" of the electrophysiological derangement induced by the administration of standard HD three times a week for years ("electric disequilibrium syndrome").

Transcranial Doppler and systemic hemodynamic studies in septic shock

The present study outlines the relationship between cerebral and systemic hemodynamics in patients with septic shock. Sepsis is an immune mediated systemic disease in which the systemic vascular resistance (SVR) often decreases as a result of a Gram negative sepsis. The result is a hyperdynamic systemic circulation with redistribution phenomena in different organ systems. In order to study the effect of sepsis on cerebral vessels 20 patients with septic shock (12 men, 8 women, mean age 57.9 years) were subjected to both pulmonary artery catheter and transcranial Doppler (TCD) monitoring. The data were correlated to the APACHE II score and outcome. The study showed that cerebral mean and end-diastolic blood flow velocities (BFV) in the middle cerebral arteries significantly enhanced if the SVR-index decreases. In some patients a severely reduced SVRI (below 500 dynes.s/cm5.m2) was observed in combination with a downstroke latent steal phenomenon. TCD abnormalities were strongly related to disease severity and outcome. The increased BFV are explained by a mild vasospasm of the basal cerebral arteries. TCD appears to be a valuable tool to monitor the cerebral hemodynamics in these patients. They are particularly at risk for ischemic brain damage if they are subjected to therapeutic or spontaneous hyperventilation, which can potentially be detected by TCD.

[Distribution of irrigating fluid in intracellular and extracellular spaces during transurethral prostatectomy II--TUR syndrome and hyponatremia]

Thirty four patients undergoing transurethral resection of the prostate (TURP) under spinal anesthesia were assigned to a TUR syndrome (TURS) group (n = 7) or an asymptomatic (ASP) group (n = 27) depending on the clinical manifestations of the TUR syndrome. Blood loss and distribution of absorbed irrigating fluid (3% sorbitol-Uromatic S, 170 mOsm.kgH2O-1, Baxter) were computed together with serum osmolality, blood urea nitrogen and hematocrit. Postoperative serum sodium concentration and hematocrit were significantly lower in the TURS group than in the ASP group (124 +/- 8.7 vs. 133.9 +/- 5.9 mOsm.l-1 and 26. 8 +/- 4.2 vs. 35.0 +/- 4.6%, respectively). Postoperative serum osmotic pressure did not differ between the groups despite the difference in sodium concentration because 3% sorbitol could contribute to osmoles in the serum. The volume of irrigating fluid absorbed and its distribution into the intracellular space (delta ICF) did not differ between the groups. However, blood loss was significantly greater in the TURS group than in the ASP group (1457 +/- 434 ml vs. 173 +/- 450 ml, P < 0.01), and consequently extracellular fluid (ECF) volume was significantly reduced in the TURS group (-354 +/- 1201 ml vs. 802 +/- 1302 ml, P < 0.05). Thus, massive blood loss and reduced ECFs rather than dilutional hyponatremia, are thought to contribute to clinical manifestation of the TUR syndrome.

Parametric analysis of heart rate variability during hemodialysis

The problem of evaluating short-term autonomic response to hypovolemia in patients under chronic hemodialysis treatment is considered. Power spectra of the beat-to-beat heart rate variability were evaluated during the dialysis treatment in twenty hemodynamically stable and unstable patients, using a parametric technique. The autoregressive model coefficients were calculated by the modified covariance method, while model order was selected according to the minimum description length criterion. Reported results demonstrate that stable and unstable patients present markedly different spectral patterns. The efficiency of the compensatory response to hemodialysis-induced hypovolemia was evaluated through the ratio between the powers in LF and HF bands. Stable patients exhibit a LF/HF ratio greater than one with large fluctuations over the whole dialysis session. In contrast, all the unstable patients are characterized by a value of LF/HF lower than one and with a reduced time variability. This result suggests that the hemodynamic instability of the hypotension-prone patients may be due to a deficiency in the short-term compensatory response to the hemodialysis-induced hypovolemia.

ABT-299, a novel PAF antagonist, attenuates multiple effects of endotoxemia in conscious rats

ABT-299, a highly potent and selective platelet activating factor (PAF) antagonist, was found to be effective in rat models of endotoxic shock. ABT-299 inhibited and reversed LPS-induced hypotension (ED50 of .008 mg/kg, intraarterially). When given prior to LPS challenge, ABT-299 (.1 mg/kg, intravenously) completely inhibited LPS-induced intestinal damage for as long as 8 h after the administration of the antagonist. Pretreatment of rats with ABT-299 (5 mg/kg, intravenously over 4 h) prevented by 85-95% symptoms of disseminated intravascular coagulation (DIC) induced by LPS, including thrombocytopenia, prolongation of prothrombin and partial thromboplastin time, decreased serum fibrinogen, and elevation of serum fibrinogen/fibrin degradation products. A .1 mg/kg dose of ABT-299 administered orally or intravenously improved long-term survival to 80% and 90%, respectively, following a lethal dose (LD65) of LPS. ABT-299 (.1 mg/kg) was also effective in preventing hypotension and gastrointestinal damage induced by lipoteichoic acid (LTA), a putative causative agent of shock in Gram-positive infections. These results illustrate the impressive potency and duration of action of ABT-299 and support the putative role of PAF in acute models of endotoxic shock.

Antepartum and postpartum complications of twin-twin transfusion

Twin-twin transfusion is a condition that was previously associated with close to a 100% perinatal mortality. Recent reports suggest that a survival rate of about 60% can be achieved with serial amniocentesis and modern neonatal care. However, it is now apparent that the survivors of this condition have multisystem complications that can result in neonatal mortality and long-term morbidity. Fourteen cases of twin-twin transfusion were examined to determine the antenatal findings that may predict the postnatal outcomes of these infants. The overall survival was 61% (17 of 28). The mean gestation at diagnosis was 23.0 weeks (range 18-34 weeks) and the mean gestation at delivery was 29.0 weeks (range 23-37 weeks). The mean number of amniocenteses was 2.9 and the average total volume of amniotic fluid removed was 6,114 mL. Different patterns of complications were seen in the donor and recipient twins. Hypertrophic cardiomyopathy affected 9 of the recipient twins. Anuria/oliguria was found in 4 of the donor twins and none of the recipients. Periventricular leukomalacia was found in 8 twins and 7 also had mild ventriculomegaly; of the surviving 17 twins, 5 had either periventricular leukomalacia, mild ventriculomegaly or both. Amniotic fluid leakage and perforation of the intervening membrane subsequent to serial amniocentesis were seen in 5 cases. Severe intrauterine growth retardation and abnormal cardiotocographs were a common feature. These complications directly resulted in neonatal mortality and long-term morbidity in the survivors. Not all complications were detected antenatally and the severity was not able to be anticipated.

Midodrine efficacy and pharmacokinetics in a patient with recurrent intradialytic hypotension

Recurrent intradialytic hypotension, a complication of hemodialysis, is a consequence of an inadequate compensatory response or a paradoxic response to ultrafiltration-induced volume reduction. We report the use of midodrine, an alpha agonist, in an 18-year-old man with Bardet-Biedl syndrome and recurrent intradialytic hypotension. The clinical features of the intradialytic hypotensive spells are consistent with a paradoxic withdrawal of sympathetic activity, although an underlying abnormality in autonomic dysfunction cannot be excluded. Midodrine significantly increased the intradialytic blood pressure and decreased the intradialytic hypotensive episodes requiring intervention. The pharmacokinetic characteristics of the prodrug midodrine and the active metabolite de-glymidodrine in this patient with end-stage renal disease approximate those reported for patients with normal renal function. However, the prolonged terminal half-life for the active metabolite, de-glymidodrine, warrants careful administration in patients with renal failure.

Prevention of cytokine-induced hypotension in cancer patients by the pineal hormone melatonin

Hypotension is a frequent side-effect of cancer biotherapies with cytokines. Cytokine-induced hypotension would mainly depend on the stimulation of nitric oxide (NO) production, which represents the most effective endogenous vasodilator. Moreover, it has been proven that both biological activity and toxicity of cytokines are influenced by the psychoneuroendocrine system, in particular by the pineal hormone melatonin. To investigate the possible modulatory effect of melatonin on cytokine cardiovascular toxicity, we evaluated the influence of a concomitant melatonin administration on interleukin-2(IL-2)- and tumour-necrosis-factor-alpha(TNF)-induced hypotension in advanced cancer patients. The study included 116 patients with advanced solid tumour, for whom no effective standard anticancer therapy was available, who underwent cancer biotherapy with IL-2 (3 x 10(6) IU/ day s.c. every day, 6 days/week for 4 weeks) or with TNF (0.75 mg/day i.v. for 5 days) as compassionate treatment for their disease. Patients were randomized to be treated with or without a concomitant melatonin administration (40 mg/day orally in the evening, starting 7 days prior to cytokine injection). The occurrence of hypotension was significantly less frequent in patients concomitantly treated by melatonin than in those who received the cytokine alone, during either IL-2: or TNF immunotherapy (IL-2; 11/45 versus 2/46, P < 0.05; TNF: 10/23 versus 1/12, P < 0.01). This study shows that melatonin may prevent hypotension occurring during cancer immunotherapy with IL-2 or TNF. Since the pineal hormone has appeared to inhibit the activity of NO synthase from the endothelial cells, we suggest that melatonin may prevent cytokine-induced hypotension by inhibiting NO production, which plays an essential role in inducing hypotension during IL-2 and TNF biotherapies.

[Sudden syncope during spinal block under sitting position: a report of three cases]

We reported 3 cases of sudden syncope during saddle block under sitting position. Patients were healthy and had no history of fainting. Syncope occurred following hypotension and bradycardia during difficult lumbar dural punctures under sitting position. Patients were treated successfully by changing position to supine, elevating both legs and giving vasopressors. Neurocardiac syncope due to the activation of afferent cardiac C-fiber has been suggested as a possible explanation in sudden syncope, which follows head-up position or emotional change. The first sign of syncope was hypotension and bradycardia due to cardiac C-fiber reflex. How to prevent this NCS under saddle block are as follows; 1. vigorous search for history of syncope, 2. pay attention to the patients during spinal tap, 3. skillful technique in spinal tap, and 4. proper premedication including anticholinergic agents. Treatments include 1. changing position to supine, 2. elevation of both legs to increase ventricular end-diastolic pressure, and 3. use of vasopressors including phenylephrine.

Nitric oxide mediates the cardiovascular instability of haemodialysis patients

Acute hypotension is a major cardiovascular complication of haemodialysis. The cardiac output falls but the total peripheral resistance remains unchanged at the time when hypotension develops. Nitric oxide affects myocardial contraction and noradrenergic response, and regulates vascular tone. This review discusses the mechanisms of acute hypotension occurring during haemodialysis, focusing on the role of nitric oxide in the associated cardiovascular instability.

[Liver cirrhosis and cardiovascular system]

The patient with hepatocellular disease shows marked vasodilatation, accompanied by hyperdynamic circulation and opening of arteriovenous shunts. The effect of these circulatory changes and especially the profound vasodilation has only recently been investigated in detail. In patients with hepatocellular failure the extremities are flushed, the pulses bounding, the cardiac output increased and the blood pressure low. The circulation resembles what found with systemic arteriovenous fistulae. The peripheral vasodilatation and splanchnic venous pooling reduce the effective blood volume so activating baroreceptors. The secondary events which follow the vasodilation include stimulation of the sympathetic nervous system. This serves to counteract the tendency to arterial hypotension and probably contributes to renal hypoperfusion and to the hepatorenal syndrome development. The nature of the concerned vasodilators remains speculative, but is likely to be multiple. Whatever its nature, the substance might be formed by the sick hepatocyte, fail to be inactivated by it or bypass it through intra- or extra-hepatic portal systemic shunts. In cirrhosis the cardiac index and reduced systemic vascular resistance correlate with the Child's grade of liver failure. This article provides an overview of the general vasodilatory state and its effects on various organs. The mechanisms and the different vasoactive substances that might be responsible are also discussed.