Use of noninvasive positive pressure ventilation via nasal mask in patients with respiratory distress after extubation

BACKGROUND

Noninvasive positive pressure ventilation (NIPPV) has been successfully applied to provide ventilatory support in patients with chronic respiratory insufficiency as well as in selected patients with acute respiratory failure of various etiologies. To investigate the effectiveness of NIPPV via nasal mask in patients who develop respiratory distress after extubation, we prospectively studied 19 such patients (14 elective extubations and 5 self-extubations) who required no immediate reintubation.

METHODS

The BiPAP ventilatory support system (BiPAP S/T-D, Respironics Inc., Murrysville, PA) via nasal mask was used to provide NIPPV in each patient. Inspiratory pressure support was adjusted to achieve comfort as well as adequate oxygenation and ventilation.

RESULTS

Eleven patients were successfully transferred to regular oxygen supplement after an average trial of 38 hours. Persistent oral air leak despite the application of chin strap was observed in four of the eight failure cases and appeared to be the leading cause of NIPPV failure. When these patients were excluded, a success rate of 73% was achieved. Other factors contributing to failure included persistent hypoxemia, inadequate ventilation, worsening of underlying diseases and bronchial secretions. No major complication related to the use of NIPPV was observed. In the success group, respiratory rate significantly decreased by an average of 10 breaths/min at one hour after the commencement of NIPPV (p < 0.01). No significant changes of heart rate, blood pressure, Paco2 and pH were noted in either group.

CONCLUSIONS

NIPPV via nasal mask may be considered as an alternative to endotracheal reintubation in selected extubated patients with respiratory distress who require no immediate reintubation.

Coronary artery muscle bridging causing class III angina in a patient with no coronary atherosclerosis

The significance of coronary artery muscle bridging (MB) has been debated since its first angiographic description by Portsmann and colleagues in 1960 (1). The course is usually benign; however, angina, myocardial infarction, sudden death, arrhythmias, and complete heart block have been reported. In this article, we present a case of coronary artery muscle bridging which caused a patient with no angiographic evidence of atherosclerosis to experience Class III angina.

Lemierre's Syndrome: Two Cases of Postanginal Sepsis

Lemierre's disease consists of suppurative thrombophlebitis of the IJV in the presence of oropharyngeal infection and can be complicated by septic pulmonary emboli. If a patient has an oropharyngeal or deep neck infection and neck pain suspicious for IJV thrombosis, a CT or MRI is warranted to establish the diagnosis. Blood cultures should be obtained to establish the responsible organism. In most cases F. necrophorum, an anaerobic bacterium, is responsible for the sepsis. Once the diagnosis of Lemierre's disease is made, long-term, high-dose intravenous antibiotics with beta-lactamase anaerobic activity should be initiated. In cases with persistent sepsis and emboli despite appropriate medical management, ligation or excision of the IJV should be performed. Finally, if there is clinical or radiologic evidence of retrograde cavernous sinus thrombosis, the use of anticoagulants should be considered.

Lemierre's syndrome: two cases of postanginal sepsis

Lemierre's disease consists of suppurative thrombophlebitis of the IJV in the presence of oropharyngeal infection and can be complicated by septic pulmonary emboli. If a patient has an oropharyngeal or deep neck infection and neck pain suspicious for IJV thrombosis, a CT or MRI is warranted to establish the diagnosis. Blood cultures should be obtained to establish the responsible organism. In most cases F. necrophorum, an anaerobic bacterium, is responsible for the sepsis. Once the diagnosis of Lemierre's disease is made, long-term, high-dose intravenous antibiotics with beta-lactamase anaerobic activity should be initiated. In cases with persistent sepsis and emboli despite appropriate medical management, ligation or excision of the IJV should be performed. Finally, if there is clinical or radiologic evidence of retrograde cavernous sinus thrombosis, the use of anticoagulants should be considered.

Universal precautions for the otolaryngologist: techniques and equipment for minimizing exposure risk

HIV infection transmitted from a patient to a surgeon is a real concern but a remote possibility. However, given the professional and personal impact of HIV seroconversion on a physician, preventive measures need to be instituted. The CDC has developed a policy of universal precautions to help to minimize this risk. We review various measures to institute this policy and other measures that can reduce exposure to HIV. These protocols, when instituted, can maximize safety for all health care professionals and their patients.

Influence of viscosity on WIN 39996 as a contrast agent for gastrointestinal magnetic resonance imaging

RATIONALE AND OBJECTIVES

The authors discuss the influence of viscosity on the imaging properties of WIN 39996 suspension. WIN 39996 suspension is a magnetically susceptible iron ferrite that provides negative (darkening) contrast enhancement in magnetic resonance imaging of the gastrointestinal tract.

METHODS

The viscosity of WIN 39996 suspension was altered by various stress conditions (1 week to 4.5 months storage at temperatures of 5 degrees to 70 degrees C) or by various amounts of xanthan gum. Magnetic resonance imaging was performed in vitro on phantoms and in vivo on the gastrointestinal tract of anesthetized dogs.

RESULTS

The results indicated that in vitro and in vivo imaging efficacies of WIN 39996 suspension depended on the viscosity, irrespective of the means by which the viscosity was altered. Specifically, the imaging quality was suitable at viscosities > or = 36.6 cp for in vitro imaging, and > 25 cp for in vivo imaging. The lower in vivo viscosity limit for magnetic resonance imaging compared with the in vitro limit may be due to gastrointestinal peristaltic activities continuously mixing the WIN 39996 suspension to prevent gravitational settling, and the enhancement of signal blackening by intraluminal WIN 39996 that was above and below the plane of image.

CONCLUSIONS

It is speculated that the imaging quality of WIN 39996 suspension depends on the degree of dispersion of the magnetically susceptible iron ferrite in the WIN 39996 suspension, and that a minimum viscosity is needed to ensure such dispersion.

Angiosarcoma following treatment of testicular seminoma: case report and literature review

We report a case of paravertebral angiosarcoma 10 years after treatment for testicular seminoma. The patient underwent irradiation treatment to areas including the mediastinum. Tumor induction by therapeutic irradiation remains the most likely etiology. Other possibilities include a natural association between seminoma and angiosarcoma, and perhaps the use of chemotherapy.

Lipid-peptide interface: valine conformation and dynamics in the gramicidin channel

High-resolution dynamic and structural characterizations have been achieved for each of the valine side chains of the gramicidin channel while solubilized in hydrated lipid bilayers. The characterizations have been achieved by 2H NMR spectra of both oriented and unoriented samples obtained at 36 and 5 degrees C, respectively. Powder patterns displaying intermediate time frame averaging provide dynamic information, and quadrupole splittings from aligned samples provide orientational constraints for the side chain structure. Librational amplitudes for each site throughout the side chain have also been characterized. Val6 and Val8 are shown to be fixed in rotameric states, potentially constraining two of the indole rings and the functionally important indole dipole moment orientations. Val1 and Val7 undergo three-state jump motions. The jump frequencies increase from the microsecond to nanosecond time frame upon increasing the temperature through the lipid phase transition. For the same temperature range, there is no evidence for changes in conformational state populations. Despite small differences in the substate populations for the two residues, the motions may be loosely coupled as indicated by the high-resolution structure.

Ricin A immunotoxins of IgG and Fab of anti-CALLA monoclonal antibody: effect of water soluble long-chain SPDP on conjugate yield, immunoselectivity and cytotoxicity

The water soluble long-chain crosslinker, sulfo-succinimidyl-6-[3'-(2-pyridyldithio)-propionamido]hexanoate (S-LC-SPDP) was used to prepare ricin A chain (RTA) immunotoxins constructed with whole IgG and Fab fragments of the anti-common acute lymphoblastic leukemia antigen (CALLA) monoclonal antibody. In this study, a) S-LC-SPDP modification efficiencies of whole IgG and Fab, b) conjugation yields of the immunotoxins prepared and c) in vitro immunoreactivity and cytotoxicity of immunotoxins constructed were examined. IgG-RTA and Fab-RTA immunotoxins were prepared with 67.3% and 57.0% conjugation yields, respectively. These long spacer intermolecular linked immunotoxins were selectively immunoreactive and cytotoxic against to immunogenic Daudi cells but little or no-binding and cytotoxic against to antigen K562 cells. Both IgG-RTA and Fab-RTA immunotoxins were 210- and 45-fold more active than intact RTA in vitro, respectively.

Increased safety by two-stage hepatectomy with preoperative portal vein embolization in rats

We evaluated the usefulness of preoperative portal vein embolization (PVE) in rats for increasing the safety of liver resection. During PVE, portal vein branches that perfused the central and left lobes of the liver were embolized. Liver weight, the elimination of indocyanine green, and the number of Kupffer cells were examined 7 days after PVE and in intact rats. Then we examined rats that had undergone PVE (PVE group), rats in which the embolized part of the liver was resected 7 days after PVE (PVE-Hx group), rats without PVE in which the same lobes of the liver were resected (Hx group), and rats that had undergone a sham operation (sham-operation group) for liver weight, the mitotic index of the hepatocytes, serum alanine aminotransferase activity, total bilirubin, and antithrombin III activity. Some rats in the four groups received an intravenous injection of 0.5 or 2.5 mg/kg endotoxin 48 hr after the operation (the second operation, if done), and the 24-hr survival rate was calculated. Some rats given 0.5 mg/kg endotoxin were killed 6 hr after the injection, and the extent of liver injury was examined biochemically and histologically. Seven days after PVE, the nonembolized part of the liver was about twice the weight of the corresponding lobes in the intact rats, the density of Kupffer cells was doubled, and the hepatic function per unit weight was about the same as that in these controls. Hepatic dysfunction and the endotoxin-induced liver injury were significantly slighter in the PVE and PVE-Hx groups than in the Hx group. Preoperative PVE could make hepatectomy safer.

Cerebral effects of nitrous oxide during isoflurane-induced hypotension in the pig

We have studied the effects of nitrous oxide on cerebral blood flow (CBF), cerebral blood flow velocity (CBFV) and intracranial pressure (ICP) during isoflurane-induced hypotension in 10 pigs. CBF was measured using laser Doppler flowmetry, CBFV in the right middle cerebral artery was calculated using Doppler ultrasound and ICP was measured using an extradural ICP monitor. Each animal was studied under four conditions, examined sequentially: (i) mean intra-arterial pressure (MAP) 85 mm Hg, maintained with isoflurane, (ii) MAP 50-55 mm Hg, induced by isoflurane only, (iii) MAP 85 mm Hg, maintained with isoflurane and 50% nitrous oxide, and (iv) MAP 50-55 mm Hg, induced by isoflurane and 50% nitrous oxide. No significant differences were noted between conditions with respect to ICP. There was a significant difference in CBF during condition (ii) compared with (i) (mean 75(SD 21) vs 100(0)%) and during condition (iv) compared with (iii) (90(26) vs 109(13)%). Animals under condition (iv) exhibited a 20% reduction in CBFV compared with those under condition (iii) (57 vs 69 cm s-1). For animals under normotensive conditions, addition of nitrous oxide to isoflurane resulted in a 16% increase in CBFV (69 vs 60 cm s-1). Comparing isoflurane-induced hypotension ((ii) vs (iv)), there was no statistical difference in either CBF or CBFV on addition of 50% nitrous oxide. The correlation between changes in CBF and CBFV was not significant. We conclude that the use of nitrous oxide during isoflurane-induced hypotension has no significant effect on CBF, CBFV or ICP compared with the use of isoflurane alone.

Thermal hyperalgesia accelerates and MK-801 prevents the development of tachyphylaxis to rat sciatic nerve blockade

BACKGROUND

Tachyphylaxis to local anesthetics has been shown to be promoted by longer interanalgesic intervals between injections. We hypothesized that thermal hyperalgesia also would accelerate the development of tachyphylaxis. The n-methyl-D-aspartate antagonist ((+)-5 methyl-10,11-dihydro-5H-dibenzo (a,d) cyclohepten-5,10-imine, or dizocilpine) (MK-801) has been shown to prevent thermal hyperalgesia. We therefore also hypothesized that MK-801 would prevent tachyphylaxis.

METHODS

Catheters were surgically implanted in rats along the sciatic nerve. After recovery and conditioning to the testing paradigm, they received repeated injections of lidocaine or 2-chloroprocaine followed by motor block testing with or without hot-plate testing at 48, 52, or 56 degrees C. In other experiments, MK-801 or saline was administered by intraperitoneal injection before sciatic nerve local anesthetic injection and sensory and motor testing.

RESULTS

Rats receiving repeated lidocaine or 2-chloroprocaine injections, when repeatedly subjected to hot-plate testing at 56 degrees C, developed thermal hyperalgesia and tachyphylaxis to motor and sensory blockade. Rats receiving either no hot-plate exposure or hot-plate exposure at 48 degrees C developed no tachyphylaxis or hyperalgesia. Rats tested at 52 degrees C developed milder hyperalgesia and developed tachyphylaxis more slowly than did rats tested at 56 degrees C. Control experiments excluded artifacts due to circadian rhythm, injection volume, and learning. Rats pretreated with MK-801 showed no tachyphylaxis over a series of three injections.

CONCLUSIONS

Thermal hyperalgesia accelerates the development of tachyphylaxis to rat sciatic nerve blockade, and MK-801 prevents tachyphylaxis in this model. n-Methyl-D-aspartate receptor antagonists may have future clinical utility in increasing the duration of effectiveness of prolonged local anesthetic administration.

Histologic changes in the breast after fine-needle aspiration

Fine-needle aspiration biopsy (FNAB) of the breast has been widely used in many centers worldwide for the initial management of patients with breast lumps. However, little has been written on the morphologic changes secondary to this commonly applied procedure. Thus we performed a retrospective study on 184 consecutive breast-excision specimens with a history of FNAB. Seventeen cases (9.2%) showed changes definitely attributable to the FNAB procedure, including three cases of near total destruction of the lesion as a result of hemorrhage (one case) or infarction (two cases), focal hemosiderin deposition (seven cases), hemorrhage with organization at the periphery (six cases), and a case of ductal papilloma showing a previously undescribed occurrence of benign epithelial implantation. The latter exhibited alarming histologic features simulating invasive carcinoma by virtue of the presence of small narrow tubules with mild cellular atypia haphazardly distributed in the fibrogranulation tissue around the papilloma; the tubules were confirmed to be benign by the presence of muscle-specific actin-positive myoepithelial cells. Other changes were possibly attributable to the FNAB procedure, including linear necrosis in the peripheral portion of the tumor (six cases), intraluminal hemorrhage in fibroadenoma (five cases), and multicentric hemorrhage in the mucinous carcinomas (four cases). We conclude that the rare occurrence of extensive tissue necrosis after FNAB can pose great difficulties in definitive diagnosis of the lesion in the subsequent excision specimen. Other changes are relatively minor, but the occurrence of benign implantation after FNAB may lead to an erroneous diagnosis of invasive carcinoma.

Subcutaneous T-cell lymphoma presenting as panniculitis in children: report of two cases

Two cases of peripheral T-cell lymphoma with primarily subcutaneous involvement and clinically presenting as panniculitis were reported in two children. One child developed florid hemophagocytic syndrome and was treated by combination chemotherapy but died 14 months later of disseminated fungal infection. The other child had mild systemic symptoms but no histological evidence of hemophagocytosis. Despite a more florid lymphomatous infiltrate, he attained a complete remission after a short course of prednisone and remains symptom-free at 3 years. Our report confirms that subcutaneous T-cell lymphoma is a distinct clinicopathological entity and highlights the two modes of clinical presentation. The development of florid hemophagocytic syndrome indicates a bad prognosis. This entity must be distinguished from other causes of panniculitis and immunophenotypic analysis of the atypical cells is essential in the diagnosis. Combination chemotherapy is the treatment of choice, but in patients who pursue an indolent course the administration of aggressive chemotherapy may be deferred.

Effect of porcine somatotropin (pST) treatment and withdrawal on performance and adipose tissue cellularity in finishing swine

A 10-wk trial was conducted with 60 barrows and 60 gilts (initial weight = 47 kg) to investigate the effect of pST treatment (3 mg/d) for wk 0 to 5, 5 to 10, or 0 to 10 on performance, carcass traits, and adipose tissue cellularity of finishing hogs. The primary objective of the study was to determine the effect of 5 wk of pST treatment followed by 5 wk of withdrawal on performance and carcass traits relative to a control or to pigs treated for the entire period. After 5 wk, pST-treated pigs exhibited improved (P < .001) gain (11%) and efficiency (22%) and decreased (P < .001) feed intake (-22%) and 10th rib backfat accretion (-93%, P < .001). There was an increase in adipose cell number/gram of tissue (control, 2.57 vs pST, 3.36 x 10(6)/g; P < .005) and a decrease in cell diameter (control, 72.4 vs pST, 67.2 microns; P < .005). Backfat thickness and cell diameter increased in control pigs from wk 5 to 10. During the last 5-wk period, pST-treated animals continued to exhibit improved performance and maintained adipose cell size distribution and number similar to the pST-treated pigs at wk 5. Pigs treated for the first 5 wk and withdrawn from treatment for the second 5 wk had decreased efficiency (-12%, P < .05) and a twofold increase in backfat accretion (P < .001) relative to control. The increase in backfat thickness was accompanied by an increase in adipocyte diameter, indicative of lipid filling. Most of the benefits of pST observed during the first 5 wk were lost during the withdrawal period. Reductions in carcass fat in response to pST treatment are at least partially accounted for by inhibition of lipid filling in adipose tissue, an effect that is reversed upon cessation of treatment.

Side-chain structure and dynamics at the lipid-protein interface: Val1 of the gramicidin A channel

High resolution dynamics and structural information has been resolved from 2H solid-state NMR spectra of the Val-1 side-chain of the gramicidin channel in a lipid bilayer. Both powder pattern lineshapes and spectra from uniformly aligned samples of gramicidin in lipid bilayers have been analyzed to achieve a fully consistant interpretation of the data. Torsional motions about the C alpha C beta axis (chi 1) are shown to be three-state jumps in which the occupancy of the states is given by the ratio, 75:15:10 for the chi 1 angles of 184 degrees:304 degrees:64 degrees. The dominant conformer is also the most common conformation observed for valines in well defined protein structures. The distribution of conformational substates that represents the chi 1 dynamics appears to be largely independent of the lipid phase transition and the hydration of the sample. However, there is evidence that the residence time between jumps is dependent on the lipid phase transition. Although this time is shown to be approximately 1 microseconds below the phase transition temperature, it is in the fast exchange limit above the transition temperature.