The relation between adrenal function and the severity of bronchial hyperresponsiveness in children as measured by the methacholine provocation test

BACKGROUND

There is no satisfactory explanation why some individuals experience severe attacks of asthma, yet others, exposed to similar stimuli, have a milder form of the disease.

OBJECTIVE

We tested the hypothesis that children with more severe disease may have relative adrenal insufficiency compared to the children with milder disease.

PATIENTS AND METHODS

Sixteen children with chronic asthma aged 8-16 years old were studied. Adrenal function was evaluated by the 24-h excretion of urinary free cortisol (UFC) before and after ACTH stimulation, and by plasma cortisol levels before and 60 min after ACTH administration. The severity of bronchial hyperresponsiveness was evaluated by the methacholine provocation test.

RESULTS

Nine children had 20% fall in forced expiratory volume in 1 sec (FEV1) after a provocative concentration (PC20FEV1) of methacholine > or =2.5 mg/ml and were considered as having mild-moderate bronchial hyperresponsiveness (Group A). Seven children had a PC20FEV1 of < or =1.25 mg/ml and were considered as having severe bronchial hyperresponsiveness (Group B). No significant difference was found between the peak plasma cortisol response to ACTH between the two groups (634+/-182 and 586+/-137 nmol/l, respectively). However, there was a significant statistical difference (p <0.01) in the 24-h UFC response to ACTH between the children from Group A (345+/-107 nmol/m2 ) and the children from Group B (161+/-125 nmol/m2).

CONCLUSIONS

Based on the low levels of 24-h UFC secretion in severely asthmatic children in our study, we propose the encouragement of provision of a short course of inhaled steroids to be kept at home for the emergency therapy of those children identified as having high-risk asthma.

Understanding the bariatric client and providing a safe hospital environment

Mobility is a basic human need that, when not met, leads to a cascade of physical problems. Meeting the challenge of safe mobility for bariatric patients is a concern for many healthcare institutions. More than 20% of the adult population now has a body mass index equal to or greater than 30 and are classified as obese. Obesity is associated with many well-known health risks, including heart disease, metabolic disorders, and cancer. Nurses should be aware of these health risks, the interplay between mobility and health risks, and the national guidelines for treating the obese patient population. This article presents an overview of national guidelines for identifying, evaluating, and treating bariatric patients and identifies issues that create challenges to providing a safe environment for mobility among hospitalized obese patients.

Propofol dosing regimens for ICU sedation based upon an integrated pharmacokinetic-pharmacodynamic model

BACKGROUND

The pharmacology of propofol infusions administered for long-term sedation of intensive care unit (ICU) patients has not been fully characterized. The aim of the study was to develop propofol dosing guidelines for ICU sedation based on an integrated pharmacokinetic-pharmacodynamic model of propofol infusions in ICU patients.

METHODS

With Institutional Review Board approval, 30 adult male medical and surgical ICU patients were given target-controlled infusions of propofol for sedation, adjusted to maintain a Ramsay sedation scale score of 2-5. Propofol administration in the first 20 subjects was based on a previously derived pharmacokinetic model for propofol. The last 10 subjects were given propofol based on a pharmacokinetic model derived from the first 20 subjects. Plasma propofol concentrations were measured, together with sedation score. Population pharmacokinetic and pharmacodynamic parameters were estimated by means of nonlinear regression analysis in the first 20 subjects, then prospectively tested in the last 10 subjects. An integrated pharmacokinetic-pharmacodynamic model was used to construct dosing regimens for light and deep sedation with propofol in ICU patients.

RESULTS

The pharmacokinetics of propofol were described by a three-compartment model with lean body mass and fat body mass as covariates. The pharmacodynamics of propofol were described by a sigmoid model, relating the probability of sedation to plasma propofol concentration. The pharmacodynamic model for propofol predicted light and deep levels of sedation with 73% accuracy. Plasma propofol concentrations corresponding to the probability modes for sedation scores of 2, 3, 4, and 5 were 0.25, 0.6, 1.0, and 2.0 microg/ml. Predicted emergence times in a typical subject after 24 h, 72 h, 7 days, and 14 days of light sedation (sedation score = 3 --> 2) with propofol were 13, 34, 198, and 203 min, respectively. Corresponding emergence times from deep sedation (sedation score = 5 --> 2) with propofol were 25, 59, 71, and 74 h.

CONCLUSIONS

Emergence time from sedation with propofol in ICU patients varies with the depth of sedation, the duration of sedation, and the patient's body habitus. Maintaining a light level of sedation ensures a rapid emergence from sedation with long-term propofol administration.

A double-blind, randomized comparison of i.v. lorazepam versus midazolam for sedation of ICU patients via a pharmacologic model

BACKGROUND

Benzodiazepines, such as lorazepam and midazolam, are frequently administered to surgical intensive care unit (ICU) patients for postoperative sedation. To date, the pharmacology of lorazepam in critically ill patients has not been described. The aim of the current study was to characterize and compare the pharmacokinetics and pharmacodynamics of lorazepam and midazolam administered as continuous intravenous infusions for postoperative sedation of surgical ICU patients.

METHODS

With Institutional Review Board approval, 24 consenting adult surgical patients were given either lorazepam or midazolam in a double-blind fashion (together with either intravenous fentanyl or epidural morphine for analgesia) through target-controlled intravenous infusions titrated to maintain a moderate level of sedation for 12-72 h postoperatively. Moderate sedation was defined as a Ramsay Sedation Scale score of 3 or 4. Sedation scores were measured, together with benzodiazepine plasma concentrations. Population pharmacokinetic and pharmacodynamic parameters were estimated using nonlinear mixed-effects modeling.

RESULTS

A two-compartment model best described the pharmacokinetics of both lorazepam and midazolam. The pharmacodynamic model predicted depth of sedation for both midazolam and lorazepam with 76% accuracy. The estimated sedative potency of lorazepam was twice that of midazolam. The predicted C50,ss (plasma benzodiazepine concentrations where P(Sedation > or = ss) = 50%) values for midazolam (sedation score [SS] > or = n, where n = a Ramsay Sedation Score of 2, 3, ... 6) were 68, 101, 208, 304, and 375 ng/ml. The corresponding predicted C50,ss values for lorazepam were 34, 51, 104, 152, and 188 ng/ml, respectively. Age, fentanyl administration, and the resolving effects of surgery and anesthesia were significant covariates of benzodiazepine sedation. The relative amnestic potency of lorazepam to midazolam was 4 (observed). The predicted emergence times from sedation after a 72-h benzodiazepine infusion for light (SS = 3) and deep (SS = 5) sedation in a typical patient were 3.6 and 14.9 h for midazolam infusions and 11.9 and 31.1 h for lorazepam infusions, respectively.

CONCLUSIONS

The pharmacology of intravenous infusions of lorazepam differs significantly from that of midazolam in critically ill patients. This results in significant delays in emergence from sedation with lorazepam as compared with midazolam when administered for ICU sedation.

Cation metabolism during propofol sedation with and without EDTA in patients with impaired renal function

OBJECTIVE

To compare the effects of propofol with and without disodium edetate (EDTA) on cation metabolism in intensive care unit (ICU) patients with renal insufficiency who received propofol or propofol plus EDTA (propofol EDTA) for sedation and mechanical ventilation.

DESIGN

Double-blind, randomised, multicentre study.

SETTING

Medical and surgical ICUs from 5 hospitals.

PATIENTS

Thirty-nine ICU patients with acute and chronic renal impairment expected to require at least 24 hours of continuous sedation and respiratory failure necessitating mechanical ventilation.

INTERVENTIONS

Propofol or propofol EDTA administered for sedation by continuous intravenous infusion.

MEASUREMENTS AND RESULTS

The depth of sedation, as measured by the Modified Ramsay Sedation Scale, was similar in the 2 groups, when adjusted for dosing differences. The amount of propofol required to maintain adequate sedation was decreased in both groups compared to propofol requirements in ICU patients with normal renal function. EDTA levels were elevated at baseline in both groups. In the propofol EDTA group, the EDTA levels increased further by 20 % but decreased to below baseline EDTA levels at 48 hours after sedation. In the propofol group, EDTA levels decreased during sedation and remained below baseline levels at 48 hours after sedation. PATIENTS in both groups were hypocalcaemic and hyperphosphataemic at baseline with low levels of 1,25-dihydroxyvitamin D and elevated parathyroid hormone (PTH) levels. Other than a slight difference in ionised serum calcium levels at 4 h after the start of sedation, there were no significant differences observed in serum calcium levels between the two groups. There were no significant differences in 1,25-dihydroxyvitamin D or PTH levels over time between the two groups. There was no significant effect on renal function in either group.

CONCLUSIONS

The results of this study suggest that adding EDTA to propofol does not adversely affect cation homeostasis or renal function when used for sedation of ICU patients with renal insufficiency. Although EDTA levels increased over time from baseline levels in patients with renal insufficiency who receive propofol EDTA, this increase does not appear to be clinically significant, and EDTA levels return to below baseline levels within 48 hours of discontinuing the propofol EDTA infusion. The efficacy of propofol with and without EDTA also appears comparable in these patients.

Heliox use in the treatment of acute hyperammonemia

The objective of this study was to evaluate a new method for the treatment of acute hyperammonemia with a helium-oxygen mixture (heliox). We conducted a prospective, randomized, controlled study of male Sprague-Dawley rats. Experimental hyperammonemia was induced by 7 days of a high-ammonia diet. Subsequently, the animals were randomly divided into two groups: the study group treated with heliox breathing for 24 hours and a control group breathing room air for 24 hours. A prospective, randomized, controlled laboratory animal study was conducted at an animal research facility. The baseline plasma ammonia level was 9.49 +/- 10.96 micromol/L. After 7 days of a high-ammonia diet, the plasma ammonia level rose to 31.53 +/- 8.86 micromol/L. There was a significant statistical difference between the plasma ammonia level following 24 hours of heliox therapy (23.14 +/- 13.97 micromol/L) and the ammonia level in the control group (42.31 +/- 24.25 micromol/L) (P < .05). Heliox breathing was found to be an efficient treatment modality for decreasing plasma ammonia levels in an animal model. Further studies are required to evaluate its potential application in the treatment of patients with hyperammonemia.

Optimization of a novel bioerodible device based on auto-catalyzed poly(ortho esters) for controlled delivery of tetracycline to periodontal pocket

Local delivery of antimicrobial agents in inflamed periodontal pocket has been shown to be effective in reducing periodontopathic microorganisms. This research focuses on developing and characterizing bioerodible formulations based on auto-catalyzed poly(ortho esters) (POExLAy) for modulated release of tetracycline over 2 weeks. POExLAy are a new versatile family of POE-containing lactoyl lactyl dimers in the polymer backbone. By modifying the proportion of lactic acid in the polymer, viscous or solid materials having different degradation rate can be produced. The formulations can be either injected or placed as a solid device directly into the periodontal pocket. Tetracycline-free base incorporated into these materials was released within 10-14 days depending on polymer structure. Increase in lactic acid content in the polymer tended to increase the drug release rate and to reduce the initial lag time. Tetracycline release from such bioerodible delivery system occurs predominantly by surface erosion of the polymeric matrix, leading to kinetics which can be zero order. This periodontal drug delivery system is designed to be used as an adjunct in the treatment of periodontal diseases. Clinical studies are currently in progress.

Release of BSA from poly(ortho ester) extruded thin strands

A solventless procedure was used where powdered polymer and micronized protein were intimately mixed and then extruded into 1 mm strands that were cut to the desired length. The polymers used were poly(ortho esters) specifically designed to allow extrusion in the neighborhood of 70 degrees C. At these temperatures many proteins maintain activity in the dry state. In vitro erosion and BSA release results indicate that after a fairly long lag-time, BSA release and polymer erosion occur concomitantly indicating an erosion-controlled process. The lag-time could be eliminated by the addition to the mixture prior to extrusion between 1 and 5 wt% poly(ethylene glycol) or its methoxy derivatives. The lag-time could also be eliminated by using an AB-block copolymer where A is poly(ortho ester) and B is poly(ethylene glycol).

Onset of accumulation of PrPres in murine ME7 scrapie in relation to pathological and PrP immunohistochemical changes

In a murine scrapie model, three different methods (immunohistochemistry, Western blotting and histoblotting) for determining disease-specific PrP accumulation were compared. The incubation period of ME7 scrapie in the F1 cross of C57 BL and VM/Dk mice is about 230 days. Mice show hippocampal neuronal loss from 160-180 days post-inoculation (dpi), CA1 neuron dendritic spine atrophy at 126 dpi, and axon terminal degeneration and synaptic loss from 84-98 dpi. Infectivity titres of at least 100 are present from 40 dpi. PrP was detected immunohistochemically at 60 dpi in the hippocampus and in the thalamus. Thus, PrP accumulation in the hippocampus precedes even the earliest neurodegenerative changes. Low amounts of PrP immunolabelling were found between 60 dpi and 126 dpi, after which the intensity increased markedly. The histoblot method detected PrPres in one of four mice at 100 dpi. Western blotting of whole brains first identified the PrPres at 80 dpi. Thus, in our hands, the most sensitive method for detecting disease-specific accumulations of PrP was immunohistochemical examination. However, immunohistochemical methods are unable to distinguish the normal and abnormal isoforms of PrP. It is therefore possible that the initial accumulation of PrP takes place as PrPsen and that the translation of PrPsen to PrPres does not take place until the later stages of the disease process. The accumulation of disease-specific PrP lags behind the development of infectivity titres. The relative rates of increase of infectivity titre and PrP accumulation are different, suggesting that these parameters may be measures of different biological events.

Peritoneal ventilation with oxygen improves outcome after hemorrhagic shock in rats

OBJECTIVE

In experimental pulmonary consolidation with hypoxemia in rabbits, peritoneal ventilation (PV) with 100% oxygen (PV-O2) improved PaO2. We hypothesized that PV-O2 could improve outcome after hemorrhagic shock (HS) with normal lungs, by mitigating dysoxia of the abdominal viscera.

DESIGN

Randomized, controlled, laboratory animal study.

SETTING

University animal research facility.

SUBJECTIVE

Male Sprague-Dawley rats.

INTERVENTIONS

Thirty rats under light anesthesia (N2O/oxygen plus halothane) and spontaneous breathing underwent blood withdrawal of 3 mL/100 g over 15 mins. After volume-controlled HS phase 1 of 60 mins, resuscitation phase 2 of 60 mins included infusion of shed blood and, if necessary, additional lactated Ringer's solution intravenously to control normotension from 60 to 120 mins. This was followed by observation phase 3 for 7 days. We randomized three groups of ten rats each: group I received PV-O2, starting at 15 mins of HS at a rate of 40 inflations/min, and a peritoneal "tidal volume" of 6 mL, until the end of phase 2. Group II received the same PV with room air (PV-Air). Control group III was treated without PV.

MEASUREMENTS AND MAIN RESULTS

During the second half of HS phase 1, mean arterial pressures were higher in the PV-O2 group I compared with the PV-Air group II and control group III (p < .05). All 30 rats survived the 120 mins of phases 1 and 2. Survival to 7 days was achieved by ten of ten rats in PV-O2 group I; by nine of ten in PV-Air group II; and by five of ten in control group III (p < .05 vs. group I; NS vs. group II). Survival times of <7 days were 5 days in the one death of group II and ranged between 6 hrs and 4 days in the five deaths of group III. In 7-day survivors, neurologic deficit scores (0% to 10% = normal, 100% = death) were normal, ranging between zero and 8%. Necropsies of rats that died during phase 3 showed multiple areas of necrosis of the gut, some with perforations. Necropsies in the five survivors to 7 days of group III showed marked macroscopic and microscopic changes (scattered areas of necrosis of stomach and intestine, adhesions, and pale areas in the liver). These changes were absent or less severe in the nine survivors of group II. Viscera appeared normal in all ten rats of PV-O2 group I.

CONCLUSIONS

Peritoneal ventilation with oxygen during and after severe hemorrhagic shock in rats seems to decrease morbidity and mortality by helping preserve viability of abdominal viscera.

Comparison of intranasal midazolam with intravenous diazepam for treating febrile seizures in children: prospective randomised study

OBJECTIVE

To compare the safety and efficacy of midazolam given intranasally with diazepam given intravenously in the treatment of children with prolonged febrile seizures.

DESIGN

Prospective randomised study.

SETTING

Paediatric emergency department in a general hospital.

SUBJECTS

47 children aged six months to five years with prolonged febrile seizure (at least 10 minutes) during a 12 month period.

INTERVENTIONS

Intranasal midazolam (0.2 mg/kg) and intravenous diazepam (0.3 mg/kg).

MAIN OUTCOME MEASURES

Time from arrival at hospital to starting treatment and cessation of seizures.

RESULTS

Intranasal midazolam and intravenous diazepam were equally effective. Overall, 23 of 26 seizures were controlled with midazolam and 24 out of 26 with diazepam. The mean time from arrival at hospital to starting treatment was significantly shorter in the midazolam group (3.5 (SD 1.8) minutes, 95% confidence interval 3.3 to 3.7) than the diazepam group (5.5 (2.0), 5.3 to 5.7). The mean time to control of seizures was significantly sooner (6.1 (3.6), 6.3 to 6.7) in the midazolam group than the diazepam group (8.0 (0.5), 7. 9 to 8.3). No significant side effects were observed in either group.

CONCLUSION

Seizures were controlled more quickly with intravenous diazepam than with intranasal midazolam, although midazolam was as safe and effective as diazepam. The overall time to cessation of seizures after arrival at hospital was faster with intranasal midazolam than with intravenous diazepam. The intranasal route can possibly be used not only in medical centres but in general practice and, with appropriate instructions, by families of children with recurrent febrile seizures at home.

Poly(ortho esters) - their development and some recent applications

Poly(ortho esters) have been under development since the early 1970s and four families of such polymers have been described. Of most interest are poly(ortho ester) III and poly(ortho ester) IV. Poly(ortho ester) III is a semisolid material that has been shown to be highly biocompatible and is currently being investigated as an adjunct to glaucoma filtering surgery and other ocular applications. However, the polymerization is difficult to control and is not readily scaled up. Poly(ortho ester) IV can be easily prepared in a highly reproducible manner, is very stable provided moisture is rigorously excluded and has also been shown to be highly biocompatible. It is currently under development for a variety of applications, such as ocular delivery, protein release, post-operative pain treatment and post-operative cancer treatment.

Development of a poly(ortho ester) prototype with a latent acid in the polymer backbone for 5-fluorouracil delivery

A study has been carried out to determine whether the latest family of poly(ortho esters) can be converted into a practical delivery system. This polymer differs from the previously described polymers in that it incorporates a short segment of a latent acid in the polymer backbone. The following issues were specifically addressed: (a) can the erosion and drug release be reproducibly controlled to yield the desired drug release kinetics and erosion rates? (b) Is the polymer stable during radiation sterilization, on storage and on fabrication? (c) Can the polymer be prepared reproducibly at the desired molecular weights and molecular weight distribution? (d) Is the polymer safe for its intended application and does the in vivo erosion proceed to completion? (e) Can the polymer be easily fabricated into desired configurations? Studies have shown that if the synthesis is carefully controlled, the desired molecular weights can be reproducibly prepared, that the polymer is reasonably stable after irradiation at 24 kGy and during storage at room temperature under anhydrous conditions, and that it can be safely thermally fabricated at temperatures in the neighborhood of 120 degrees C. When polymer devices were implanted intraperitoneally in rats the polymer eroded to completion without any overt toxicity as determined by the measured parameters.

Talismans and amulets in the Pediatric Intensive Care Unit: legendary powers in contemporary medicine

BACKGROUND

For centuries talismans and amulets have been used in many cultures for their legendary healing powers.

METHODS

We asked the parents of every child (Jews and Arabs) admitted to the Pediatric Intensive Care Unit over a 2 month period to complete a questionnaire, which included demographic data on the patient and the family, the use of talismans or other folk medicine practices, and the perception of the effects of these practices on the patient's well-being. A different questionnaire was completed by the ICU staff members on their attitude toward the use of amulets.

RESULTS

Thirty percent of the families used amulets and talismans in the ICU, irrespective of the socioeconomic status of the family or the severity of the patient's illness. Amulets and talismans were used significantly more by religious Jews, by families with a higher parental educational level, and where the hospitalized child was very young. The estimated frequency of amulet use by the children's families, as perceived by the staff, was significantly higher than actual use reported by the parents. In Jewish families the actual use of amulets was found to be 30% compared to the 60% rate estimated by the medical staff; while in Moslem families the actual use was zero compared to the staff's estimation of about 36%. Of the 19 staff members, 14 reported that the use of amulets seemed to reduce the parents' anxiety, while 2 claimed that amulet use sometimes interfered with the staff's ability to carry out medical treatment.

CONCLUSIONS

The use of talismans in a technologically advanced western society is more frequent than may have been thought. Medical and paramedical personnel dealing with very ill patients should be aware of the emotional and psychological implications of such beliefs and practices on patients and their families.

The number of CD34+ cells mobilized into the peripheral blood can predict the quality of subsequent collections

PBPC were mobilized using a variety of chemotherapy regimens plus G-CSF in a group of 126 consecutive patients. Data are presented that show a close correlation between the number of CD34+ cells mobilized into the peripheral blood (PB) and the number of CD34+ cells subsequently collected by leukapheresis (R = 0.904). On the basis of this correlation, a regression formula was calculated that could give an estimate of the total number of CD34+ cells likely to be collected by leukapheresis from a given number of CD34+ cells per microliter PB. An easy-to-read table has been compiled to show how this type of analysis can be applied to predict the likely dose of CD34+ cells that will be obtained by leukapheresis over a wide range of patient weights.

Intranasal midazolam as a treatment of autonomic crisis in patients with familial dysautonomia

To evaluate the efficacy and safety of intranasal midazolam in the treatment of autonomic crises in children with familial dysautonomia, intranasal midazolam was administered at the hospital to six patients during nine episodes of autonomic crisis. Treatment was successful in seven of nine episodes of autonomic crisis in five of six patients, with a mean interval to response of 9.25 +/- 1.25 minutes. The parents of five patients in whom the treatment was successful were instructed to use midazolam at home. At home, 16 additional episodes were treated by the parents, with successful control achieved in 14 (87%). The mean interval to response was 12.8 +/- 2 minutes. No significant side effects were observed at the hospital or at home after intranasal administration of midazolam. Midazolam, given intranasally, is effective and safe in the management of autonomic crises in patients with familial dysautonomia, either in the hospital or at home by the parents after appropriate instruction.

Visual evoked potentials in the diagnosis of headache before 5 years of age

Headache is a common complaint in children. Diagnosis of the type of headache and therapeutic approach is predominantly clinical based on a detailed history and physical examination. These data are often not available or informative in young children with headache, leading clinicians to look for diagnostic studies. We reviewed our experience with 53 children under the age of 5 years with headache. Of these, 42 (75%) children underwent neuro-imaging studies including CT scan (32 cases), MRI (10 cases), or both studies (6 cases). All were within normal limits except for two cases with a small arachnoid cyst and cerebellar hypoplasia respectively which were not directly related to the headache. Visual evoked potentials were performed in all children. There were no significant differences between the mean latencies of N(1)P(100) and N(2) of the children with clinically diagnosed migraine, however, the P(100)-N(2) amplitudes of children with migraine were significantly larger compared to those of children without migraine. Even in young children with headache, neuro-imaging studies have a very limited diagnostic value. Visual evoked potentials may also be used in this age group as a diagnostic tool, particularly when clinical symptoms are either unavailable or not characteristic.

CONCLUSION

The diagnosis of migraine in young children remains clinical, based on history obtained from children and parents; however, visual evoked potentials may support the diagnosis in this age group.