Confocal scanning laser microscopy in patients with postoperative endophthalmitis

PURPOSE

To investigate alterations of corneal layers in eyes treated for acute postoperative endophthalmitis.

METHODS

In this retrospective, nonrandomized comparative study, eyes treated with 25 gauge pars plana vitrectomy (PPV) for acute post-cataract endophthalmitis (group A) were compared to eyes receiving uneventful cataract surgery (group B) and uneventful 25 gauge PPV for epiretinal membrane (group C). After a minimum follow-up of 8 months from last surgical procedure, laser scanning in vivo confocal microscopy (IVCM) was performed.

RESULTS

Twelve eyes for each group were recruited. Comparing study eyes with control eyes of group B and C, no statistical difference was found in corneal epithelial cell density (p = n.s.), in density of nerve fibers (p = n.s.), mean grade of nerve reflectivity (p = n.s.), mean grade of nerve tortuosity (p = n.s.), mean grade of anterior keratocyte activation (p = n.s.), and corneal endothelium cell density (p = n.s.), whereas a statistically higher mean grade of posterior keratocyte activation was found in group A (p < 0.01). Epithelial and endothelial corneal morphologies were graded as regular in all groups. Langerhans cells and corneal dendritic-shaped hyper-reflective endothelial deposits were found in group A. Both findings were absent in group B and C, and the difference was statistically significant (p < 0.01).

CONCLUSIONS

IVCM was a useful tool in the detection of microscopic chronic corneal abnormalities caused by postoperative endophthalmitis. These findings confirmed the presence of a subclinical chronic corneal inflammation localized to the posterior stroma that should be related to the infectious process. Future studies might clarify pathological processes in the acute phase of postoperative endophthalmitis.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Improvement of renal function in epidermolysis bullosa patients after gluten free diet: two cases

Epidermolysis bullosa (EB) is a rare inherited genetic disease characterized by an abnormal response of the skin and mucosa to mechanical trauma. Dystrophic EB (DEB) is very often associated with many extra cutaneous complications. Those complications involve either epithelial associated tissues or other organs. In particular, several renal complications have been described for DEB in the recessive form, such as amyloidosis, post-infection glomerulonephritis, upper and lower urinary tract obstruction and IgA-Nephropathy (IgAN). In the cases reported below we have two patients diagnosed with DEB that showed compromised renal function and proteinuria. The switch of the normal diet toward a gluten free diet resulted beneficial for both patients, since renal function was rescued and proteinuria cured. Moreover, a general health status improvement was recognised, given that nutritional condition was ameliorated and bone growing enhanced. Furthermore, in both patients the presence of autoantibodies anti-COL7 indicating an autoimmune form of the disease. Therefore, patients received low doses of betametasone useful to reduce inflammatory state and to control immune system function. In conclusion, our results prompt us to hypothesized that in these patients, due to the fragility of the intestinal mucosa, the absence in the diet of gluten may be beneficial.

Endovascular Treatment of Pulmonary and Cerebral Arteriovenous Malformations in Patients Affected by Hereditary Haemorrhagic Teleangiectasia

Hereditary Haemorrhagic Teleangiectasia (HHT) is a vascular disorder of angiogenesis transmitted in an autosomal dominant pattern, characterised by heterogeneity in clinical manifestations. One of the most important organ involved is lung, including pulmonary arteriovenous malformations (PAVM). PAVM occur in 20 to 30% of the HHT population and recently are considered a marker of disease. PAVM are direct artery-to-vein connections with low pressure and without an interveining capillary bed. PAVM are classified as simple (supplied by one feeding artery) or complex (receiving blood supply from two or more feeding artery). According to the international reports, treatment it's recommendable for all PAVM with feeding vessels 3mm or larger, in order to reduce the risk of cerebral ischaemia and neurologic manifestations frequently attributed to paradoxical embolisation. Transcatheter embolotherapy of PAVM is a form of treatment based on occlusion of the feeding artery to a PAVM by using platinum coils or detachable balloons. The technique of coil embolisation involves the exact localisation of PAVM by pulmonary angiography followed by superselective percutaneous caheterisation of feeding artery obtained by using a dedicated 7F guiding catheter, which coaxially allocates a 5F hydrophilic catheter advanced in order to perform both superselective angiography of feeding artery and embolisation itself. Inside the 5F catheter the platinum coils are advanced using a .035'' guide-wire and released until an optimal occlusion of feeding artery is achieved. At the end of the procedure angiographic control is performed in order to verify the occlusion of feeding artery. The use of platinum coils is preferable over detachable balloons when feeding artery are greater than 7 mm in diameter and have irregular anatomical configuration. On the other hand, the principal advantage of using detachable balloons is that the balloon itself can be deflated and repositioned if necessary. Transcatheter embolotherapy is technically safe and clinically effective and may represent the primary choice of treatment in HHT patients. On the other hand the most common complications of this treatment (pleurisy and air embolism) can be prevented by using some tips during the embolisation procedure like "anchor technique," "scaffold technique" and "balloon assisted technique." Cerebral arteriovenous malformations (CAVM) are present in 10-20% of patients with HHT and multiple in 50% of cases. Cortical surface is the most frequent localisation. Angiography is needed to diagnose all CAVM and to clarify the angioarchitecture of the lesion. In HHT CAVM are usually either micro-AVM, with a nidus not bigger than 1 cm, or small AVM, with a nidus between 1 and 3 cm. Quite frequently there are lesions characterised by arteriovenous fistulas. In the three patterns of CAVM usually found in HHT, small AVM are the most risky for bleeding although the risk is lower than that associated with sporadic ones. It is estimated from 0.38 to 0.69% per year in spite of the general incidence of bleeding in sporadic CAVM that ranges from 2 to 4% per year. In HHT patients, at present, the precise indications and timing of treatment are not established. Trend is to treat small AVM and AVF and to follow-up micro-AVM with MRI and angiography. As for sporadic CAVM, treatment of small AVM is usually referred to stereotactic radiosurgery. Endovascular embolisation is proposable if the lesion is easily reachable by microcatheterism and the position of the microcatheter is safe. Glue is used for embolisation and the technique is briefly discussed.

Surgical and anesthesiological procedures and patients outcome in a major teaching hospital, in a major non-teaching hospital and in a minor hospital

AIM

This study was carried out to evaluate the outcome of patients in different hospitals with the aim to plan future structural and management changes.

METHODS

All the anaesthesiological and surgical procedures were observed for a 2 weeks period in a major teaching hospital (A), in a major nonteaching hospital (B) and in a minor nonteaching hospital (C) in all the patients requiring anaesthesia. The main and the co-existing diseases and the surgical and anaesthesiological treatments they received were evaluated to determine the outcome. The ASA class, the duration of the procedure, the length of staying in hospital, the transfusions of blood or derivatives, the adverse events for each patient were also observed.

RESULTS

The results showed that the patients admitted to the teaching hospital were classified in higher ASA risk classes and had surgery of longer duration, with a higher ratio of major surgery. The outcome was satisfactory in all the 3 hospitals, with a 2 days length of stay respectively in 30% (A and B) and 50% (C) of the patients. The rate of mortality was low: only 3 patients in hospital A and no patient in B and C died in a period of 2 days following surgery. Hospitals B and C showed a large use of modern techniques such as autologous blood transfusion and central and peripheral anaesthetic blocks, with a better cost-benefit ratio than the major teaching hospital.

CONCLUSIONS

This study showed good results, but it should be repeated in a few years in order to evaluate any change and possible improvement in the management and outcome of the patients.

Emergencies in hereditary haemorrhagic telangiectasia

BACKGROUND

Hereditary haemorrhagic telangiectasia (HHT) is a systemic autosomal dominant vascular disease. Although the clinical picture is that of a chronic disabling disease, vascular malformations can suddenly lead to life-threatening conditions.

AIM

To assess the frequency and type of emergency acute complications in HHT.

DESIGN

Retrospective case-note review.

METHODS

From August 2000 to December 2004, our specialized HHT centre saw 139 patients (74 males, 65 females, mean age 45.5 years, range 14-77) with a definite diagnosis of HHT. We reviewed their clinical files and recorded all visits for acute complications (massive nosebleeds, haematemesis, melaena, haematochezia, haemothorax, haemoptysis, TIA/ischaemic stroke, haemorrhagic stroke, brain abscess).

RESULTS

Fifty patients (35.9%) had at least one acute complication. There were a total of 93 visits potentially involving the emergency department. Most commonly, patients sought urgent medical attention for nosebleeds and gastrointestinal bleeding (63.4%), but there were also disorders of the brain, lung, heart and liver.

DISCUSSION

Acute complications of HHT are not uncommon and can be severe and wide-ranging. Physicians should be aware of HHT and its major complications, as a prompt diagnosis is essential to direct patients to the most appropriate therapies, and to suggest screening for visceral involvement in their relatives.

Mitochondrial dysfunction associated with cardiac ischemia/reperfusion can be attenuated by oxygen tension control. Role of oxygen-free radicals and cardiolipin

Reactive oxygen species (ROS) are considered an important factor in ischemia/reperfusion injury to cardiac myocites. Mitochondrial respiration is an important source of ROS generation and hence a potential contributor to cardiac reperfusion injury. Appropriate treatment strategy could be particularly useful to limit this ROS generation and associated mitochondrial dysfunction. In the present study, we examined the effect of lowering the oxygen tension, at the onset of the reperfusion, on various parameters of mitochondrial bioenergetics in rat heart tissue. After isolation of mitochondria from control, ischemic, normoxic and hypoxic reperfused rat heart, various bioenergetic parameters were evaluated such as rates of mitochondrial oxygen consumption, complex I and complex III activity, H2O2 production and in addition, the degree of lipid peroxidation, cardiolipin content and cardiolipin oxidation. We found that normoxic reperfusion significantly altered all these mitochondrial parameters, while hypoxic reperfusion had a protective effect attenuating these alterations. This effect appears to be due, at least in part, to a reduction of mitochondrial ROS generation with subsequent preservation of cardiolipin integrity, protection of mitochondrial function and improvement of post-ischemic hemodynamic function of the heart.

Airways humidification during mechanical ventilation. Effects on tracheobronchial ciliated cells morphology

AIM

Airways humidification during mechanical ventilation (MV) can be performed by means of heat and moisture exchangers (HME). Good performance of selected hygroscopic HME was shown in terms of tracheal temperature and humidity control and low tube obstruction rates. However, few data are available on their effects on tracheobronchial ciliated cells. The purpose of this study was to evaluate the effects of 2 different HME on ciliated cell during MV.

METHODS

Twenty consecutive patients undergoing elective surgery lasting <4 h were randomly assigned to be treated with Rusch (Group 1) or Mediflux (Group 2) hygroscopic HME. The morphology of tracheobronchial ciliated cells was evaluated from cytologic smears of endotracheal aspirate. Smears were prepared by using the thin-prep processor, stained using the Papanicolau method and examined in triplicate: recognizable respiratory cells were graded on a six-point scale, according to the normal appearance of cilia, cytoplasm and nucleus.

RESULTS

In Group 1, 178.3+37 cells were retrieved from aspirates and , 155.6+58 in Group 2 (NS). The score was 739+241 in Group 1 and 617+329 in Group 2 (NS). Cilia and end plate were undamaged in 80+17% and 81+20% cells respectively in Group 1 and in 56+23% and 62+22% cells respectively in Group 2 (P<0.01 and <0.05).

CONCLUSIONS

During MV epithelial tracheobronchial cells can be affected by the humidification device used. Our findings suggest that the 2 HME tested in the present study have a different impact on ciliated cells structure.

Epidural analgesia for labour and delivery. Current evidence

Currently, evidence-based medicine indicates that epidural analgesia (EA) labor is not associated with cesarean and instrumental delivery for dystocia. This evidence was obtained from clinical investigations of variability in clinical labor management. An optimized balance between anesthesiological and obstetric practice is vitally important for securing spontaneous delivery. The total dose of local anesthetic for EA may be associated with operative delivery when there is a lack of obstetric care standardization and co-interventions reducing unintended EA effects. Furthermore, combining local anesthetic low dose and opioid low dose may produce a new balance with obstetric management. Physiological and pharmacological knowledge together with recent clinical findings suggest that combined opioid-local anesthetic low dose EA causes minimal negative effects on labor progress and is effective and safe in terms of maternal and neonatal outcome. Internal communication between obstetricians and anesthesiologists is essential for optimizing EA labor management. Processes of health care quality management, such as medical audit and peer review, should be routinely practiced to reach this goal.

Organometallic complexes with biological molecules. XVIII. Alkyltin(IV) cephalexinate complexes: synthesis, solid state and solution phase investigations

Dialkyltin(IV) and trialkyltin(IV) complexes of the deacetoxycephalo-sporin-antibiotic cephalexin [7-(d-2-amino-2-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid] (Hceph) have been synthesized and investigated both in solid and solution phase. Analytical and thermogravimetric data supported the general formula Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O (Alk=Me, n-Bu), while structural information has been gained by FT-IR, (119)Sn Mössbauer and (1)H, (13)C, (119)Sn NMR data. In particular, IR results suggested polymeric structures both for Alk(2)SnOHceph(.)H(2)O and Alk(3)Snceph(.)H(2)O. Moreover, cephalexin appears to behave as monoanionic tridentate ligand coordinating the tin(IV) atom through ester-type carboxylate, as well as through beta-lactam carbonyl oxygen atoms and the amino nitrogen donor atoms in Alk(2)SnOHceph(.)H(2)O complexes. On the basis of (119)Sn Mössbauer spectroscopy it could be inferred that tin(IV) was hexacoordinated in such complexes in the solid state, showing skew trapezoidal configuration. As far as Alk(3)Sn(IV)ceph(.)H(2)O derivatives are concerned, cephalexin coordinated the Alk(3)Sn moiety through the carboxylate acting as a bridging bidentate monoanionic group. Again, (119)Sn Mössbauer spectroscopy led us to propose a trigonal configuration around the tin(IV) atom, with R(3)Sn equatorial disposition and bridging carboxylate oxygen atoms in the axial positions. The nature of the complexes in solution state was investigated by using (1)H, (13)C and (119)Sn NMR spectroscopy. Finally, the cytotoxic activity of organotin(IV) cephalexinate derivatives has been tested using two different chromosome-staining techniques Giemsa and CMA(3), towards spermatocyte chromosomes of the mussel Brachidontes pharaonis (Mollusca: Bivalvia). Colchicinized-like mitoses (c-mitoses) on slides obtained from animals exposed to organotin(IV) cephalexinate compounds, demonstrated the high mitotic spindle-inhibiting potentiality of these chemicals. Moreover, structural damages such as "chromosome achromatic lesions", "chromosome breakages" and "chromosome fragments" have been identified through a comparative analysis of spermatocyte chromosomes from untreated specimens (negative controls) and specimens treated with the organotin(IV) complexes.

Subarachnoid anaesthesia in caesarean delivery: effects on alertness

AIM

Subjects in spinal anaesthesia have been reported to show a decrease in the level of alertness, even when they have not received any sedative drugs.

THE AIM

of this study is to verify, in caesarean delivery if the bupivacaine subarachnoid anaesthesia, with or without intrathecal fentanyl dose, produces a sedative effect, to define the entity and to identify the mechanism that most likely causes it.

METHODS

The clinical investigation is divided into Part I (non-randomized trial) and Part II (randomized trial) and is set in the University hospital's delivery-unit. Part I: 45 pregnant women were recruited and enrolled in 3 groups: women having natural delivery (n=15), women receiving caesarean delivery with subarachnoid anaesthesia (n=15) and with general anaesthesia (n=15). Self-rating depression scale (SDS), self-rating anxiety scale (SAS), state anxiety inventory (SAI) and trait anxiety inventory (TAI) psychometric tests were patient-completed for pre-delivery anxiety evaluation. Part II: 23 pregnant women undergoing caesarean delivery were single-blind randomized to receive subarachnoid anaesthesia with single 12.75 mg 0.5% hyperbaric bupivacaine (n=10) or with 12.75 microg 0.5% hyperbaric bupivacaine and 15 mg fentanyl (n=13). Bispectral index (BIS), observer's assessment of alertness/sedation (OAA/S) scale, self-sedation visual analogic scale (VAS) and mean arterial pressure (MAP) were perioperatively monitored.

RESULTS

Part I: it was found, using SAI, a higher level of state anxiety in the pregnant women undergoing caesarean delivery than those having natural delivery (p<0.05). Part II: pregnant women receiving subarachnoid anaesthesia for caesarean delivery had a decrease of the level of alertness from 10 to 70 min after the execution of lumbar puncture (p<0.05), with a sedative peak from 35 to 45 min (p<0.01), as measured by OAA/S scale and self-sedation VAS but not by BIS. Women who received bupivacaine-fentanyl spinal anaesthesia had a more consistent sedative effect from 35 to 70 min (p<0.05).

CONCLUSIONS

Pregnant women undergoing caesarean delivery had a more elevated level of state anxiety, assessed by SAI, as seen in Part I. Subarachnoid anaesthesia in caesarean delivery is associated with a reduction of alertness level. A double mechanism might cause a clinically valuable sedative effect, observed by OAA/S scale and self-sedation VAS: decrease of the afferent spinal inputs and an anxiolytic psychophysiologic effect, induced by good outcome of the birth and mother-baby contact. Intrathecal bupivacaine-fentanyl dose produces a larger alertness decrease than single bupivacaine, because the anaesthetic block density increases. BIS was not a sensitive measure to detect the light sedation occurring in Part II of this study.

HIV Lipodystrophy Case Definition using Artificial Neural Network Modelling

Objective

A case definition of HIV lipodystrophy has recently been developed from a combination of clinical, metabolic and imaging/body composition variables using logistic regression methods. We aimed to evaluate whether artificial neural networks could improve the diagnostic accuracy.

Methods

The database of the case-control Lipodystrophy Case Definition Study was split into 504 subjects (265 with and 239 without lipodystrophy) used for training and 284 independent subjects (152 with and 132 without lipodystrophy) used for validation. Back-propagation neural networks with one or two middle layers were trained and validated. Results were compared against logistic regression models using the same information.

Results

Neural networks using clinical variables only (41 items) achieved consistently superior performance than logistic regression in terms of specificity, overall accuracy and area under the ROC curve. Their average sensitivity and specificity were 72.4 and 71.2%, as compared with 73.0 and 62.9% for logistic regression, respectively (area under the ROC curve, 0.784 vs 0.748). The discriminating performance of the neural networks was largely unaffected when built excluding 13 parameters that patients may not have readily available. The average sensitivity and specificity of the neural networks remained the same when metabolic variables were also considered (total 60 items) without a clear advantage against logistic regression (overall accuracy 71.8%). The performance of networks considering also body composition variables was similar to that of logistic regression (overall accuracy 78.5% for both).

Conclusions

Neural networks may offer a means to improve the discriminating performance for HIV lipodystrophy, when only clinical data are available and a rapid approximate diagnostic decision is needed. In this context, information on metabolic parameters is apparently not helpful in improving the diagnosis of HIV lipodystrophy, unless imaging and body composition studies are also obtained.

Macular thickness measured by optical coherence tomography (OCT) in diabetic patients

PURPOSE

1) To compare macular thickness (MT) by optical coherence tomography (OCT) in diabetics and controls; 2) to assess the relationship between MT and stage of diabetic retinopathy (DR) and macular edema (ME); 3) to quantify MT changes after laser treatment for ME.

METHODS

One-hundred and thirty-seven patients with diabetes mellitus (216 eyes) were admitted to the study and examined by stereo-color fundus photos, retinal fluorangiography and OCT. DR was classified as: 1) no DR (46 eyes: 21.3%); 2) background DR (66 eyes: 30.6%); 3) pre-proliferative DR (50 eyes: 23.1%); 4) proliferative DR (54 eyes: 25%). The study group was then divided into three ME groups: 1) no edema (65 eyes: 30.1%); 2) not clinically significant ME (no CSME) (45 eyes: 20.8%); 3) clinically significant macular edema (CSME) (106 eyes: 49.1%). Three-month follow-up tomograms were taken to evaluate eyes laser-treated only for ME. The control group consisted of 50 eyes of 50 non-diabetic, age- and sex-matched subjects.

RESULTS

MT was 369.3 +/- 163.2 microm in diabetics and 161.9 +/- 12.9 microm in controls (p < 0.001). In the four DR groups it was: 1) 211.0 +/- 37.6 microm; 2) 370.8 +/- 159.6 microm; 3) 419.1 +/- 138.2 microm; 4) 456.1 +/- 162.0 microm (p<0.001). In the three ME groups, MT was: 1)227.8 +/- 53.4 microm; 2) 321.8 +/- 124.2 microm; 3) 476.2 +/-146.6 microm (p < 0.001). In the 52 eyes treated with laser photocoagulation of the posterior pole only and with a follow-up > 3 months, MT before and after treatment was 468.2 +/- 83. 17 microm and 372.1 +/- 120.63 microm.

CONCLUSIONS

MT was greater in diabetics than controls and tended to increase with DR and ME severity. OCT is a sensitive technique for detecting early diabetic macular abnormalities and quantifying their reduction after laser treatment.

Organometallic complexes with biological molecules. XVII. Triorganotin(IV) complexes with amoxicillin and ampicillin

Novel triorganotin(IV) complexes of two beta-lactamic antibiotics, 6-[D-(-)-beta-amino-p-hydroxyphenyl-acetamido]penicillin (=amoxicillin) and 6-[D-(-)-alpha-aminobenzyl]penicillin (=ampicillin), have been synthesized and investigated both in solid and solution states. The complexes corresponded to the general formula R(3)Sn(IV)antib*H(2)O (R=Me, n-Bu, Ph; antib=amox=amoxicillinate or amp=ampicillinate). Structural investigations about configuration in the solid state have been carried out by interpreting experimental IR and 119Sn Mössbauer data. In particular, IR results suggested polymeric structures both for R(3)Sn(IV)amox.H(2)O and R(3)Sn(IV)amp*H(2)O. Moreover, both antibiotics appear to behave as monoanionic bidentate ligands coordinating the tin(IV) atom through ester-type carboxylate, as well as through the beta-lactamic carbonyl. Evidence that in none of these compounds water molecules were involved in coordination, was provided by thermogravimetric investigations. On the basis of 119Sn Mössbauer spectroscopy it can be inferred that tin(IV) was pentacoordinate in all of the complexes in the solid state, showing an equatorial R(3)Sn(IV) trigonal bipyramidal (tbp) configuration. The nature of the complexes in solution state was investigated by using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, while an 119Sn spectrum was obtained for n-Bu(3)Sn(IV)amp*H(2)O. Although 1H- and 13C-NMR measurements suggested that in dimethyl sulfoxide (DMSO)-d(6) solution the polymeric structure collapsed, due to a solvolysis process of the beta-lactamic carbonyl bonding to the organometallic moiety, the complexes have been shown to maintain the same trigonal bipyramidal configuration at tin(IV) atom by the coordination of a DMSO molecule. Cytotoxic activity of these novel semisynthetic antibiotic derivatives has been tested towards spermatocyte chromosomes of the mussel Brachidontes pharaonis (Mollusca: Bivalvia) using two different chromosome-staining techniques such as Giemsa and CMA(3). The occurrence of typical colchicinized-like (c-like) mitoses on slides obtained from animals exposed to organotin compounds, directly confirmed the high mitotic spindle-inhibiting potency of these chemicals. In addition, by comparative analysis of spermatocyte chromosomes from untreated specimens (negative controls) and specimens treated with the triorganotin(IV) complexes, structural damages such as 'achromatic lesions' and 'chromosome breakages' have been identified.

Independent lung ventilation in patients with unilateral pulmonary contusion. Monitoring with compliance and EtCO(2)

OBJECTIVE

a) to describe a non-barotraumatic ventilatory setting for independent lung ventilation (ILV); b) to determine the utility of single lung end-tidal CO(2) (EtCO(2)) monitoring to evaluate the ventilation to perfusion (V/Q) matching in each lung during ILV and for ILV weaning.

DESIGN

prospective study.

SETTING

general intensive care unit in a university teaching hospital.

PATIENTS

twelve patients with unilateral thoracic trauma needing ILV.

INTERVENTIONS AND RESULTS

ILV was started with each lung ventilated with the same tidal volume (Vt): plateau airway pressure (Pplat) was 34.2+/-3.2 cmH2O in diseased lungs (DL) and 18.1+/-1.9 cmH2O in normal lungs (NL) ( P<0.01). Static compliance (Cst) was 9.9+/-1.1 ml/cmH(2)O in DL and 19.3+/-1.7 ml/cmH(2)O in NL ( P<0.01). EtCO2 was 22.5+/-2.2 mmHg in DL and 36.6+/-1.9 mmHg in NL ( P<0.01). PaO(2)/FiO(2) was at 151+/-20. PEEP was applied on the DL and each lung was ventilated with a Vt that developed Pplat < or =26 cmH2O. With this setting, Vt given to the NL was unchanged, whereas it was reduced in the DL (238+/-30 ml vs 350+/-31 ml; P<0.01). Cst and EtCO2 were still significantly lower in the DL ( P<0.01, respectively), while the PaO(2)/FiO(2) ratio remained unchanged. Vt was then progressively increased in the DL as Pplat decreased, but remained unchanged in the NL. ILV was discontinued when Vt, Cst and EtCO(2) were the same in each lung. PaO(2)/FiO(2) ratio had then increased to 295+/-18.

CONCLUSIONS

a) during ILV, adequate oxygenation and a reduction in V/Q mismatch can be obtained by setting Vt and PEEP to keep Pplat below a safe threshold for barotrauma; b) measurement of single lung EtCO2 can be useful to evaluate progressive V/Q matching.

Broad Beam vs. Flying Spot Excimer Laser: Refractive and Videokeratographic Outcomes of Two Different Ablation Profiles After Photorefractive Keratectomy

PURPOSE

To assess the refractive outcomes and videokeratographic patterns in photorefractive keratectomy (PRK) of two last-generation excimer lasers: broad beam and flying spot lasers.

METHODS

Forty eyes were treated for a mean myopic correction of -5.59+/-2.17 D with a Ladarvision excimer laser (Autonomous Technology Corp). We compared the refractive outcomes and the videokeratographic patterns with those of 40 eyes treated with the Summit Apex Plus laser (Summit Technology Inc) for a mean myopic correction of -5.60+/-2.24 D.

RESULTS

During the 6-month follow-up, we found no significant difference in uncorrected and spectacle-corrected visual acuity, haze grade, regularity index, or decentration. The eyes treated by Ladarvision showed a lower refractive error at 1 month (P = .04), a lower incidence of central islands at 1 (P = .003) and 3 months (P = .04), a wider mean effective ablation area at 1 (P = .0004), 3 (P = .0000009), and 6 months (P = .0000000004), a less steep ablation edge at 1 (P = .0026), 3 (P = .015), and 6 months (P = .011).

CONCLUSIONS

The small beam excimer laser provides better videokeratographic outcomes, which lead to quicker refractive stability and better visual performance.

Hypoxic reperfusion limits functional impairment following cardioplegic arrest in isolated rat heart

BACKGROUND

Reperfusion injury decreases both systolic contractility and diastolic compliance. Several studies indicate that the sustained decrease in diastolic compliance is mainly due to reactive oxygen intermediates (ROI) generation and calcium overload.

METHODS

Male Wistar isolated rat hearts were divided into 2 groups (n=10 each), perfused according to Langendorff technique and exposed to 45 min of ischemia. Hearts belonging to the first group were reperfused with Krebs-Henseleit solution at 600 mmHg pO2; a 150 mmHg pO2 perfusate was utilized in the second group during the first minute and switched to 600 mmHg pO2 thereafter. Modifications in diastolic compliance and systolic contractility were assessed by changes in left ventricular end-diastolic (LVEDP) and developed pressure (LVDP), and first derivative of the pressure curve (dP/dt).

RESULTS

Increase in LVEDP values, with respect to pre-ischemic data, were detected at 1, 5, 10, 20 min following reperfusion at 600 mmHg pO2, and were respectively: +40.17+/-18.61, +57.5+/-28.8, +59.8+/-30.5 and +63.2+/-34.1 mmHg. At 150 mmHg pO2 they were: +15.69+/-13.13, +22.4+/-14.1, +26.2+/-13.7 and +28.9+/-15.8, with a significant difference within the first 20 min (p<0.05). At high pO2 levels, LVDP decreased of 53.0+/-27.35, 60.5+/-22.6, 59.8+/-23.3 and 50.7+/-25.0 mmHg, versus 42.7+/-25.7, 38.0+/-29.5, 39.2+/-30.9 and 38.7+/-32.7 mmHg at lower pO2 (p=NS). The correspondent values of the dP/dt were 37.8+/-27.7, 30.1+/-17.2, 32.2+/-13.6 and 35.4+/-14.0% of pre-ischemic values at high pO2, versus 43.3+/-27.09, 51.9+/-25.1, 50.1+/-24.6 and 53.1+/-29.9% at lower pO2. Statistical significance was lower for LVDP and dP/dt than LVEDP.

CONCLUSIONS

Diastolic functional impairment was partially reduced within the first 20 min following low pO2 reperfusion, but without any significant improvement of contractility.

Factitious HIV syndrome in young women

Factitious HIV infection has been observed at our center in women presenting with a false history of HIV/AIDS. In a 2-year period, 4 women presented for HIV-related care, indicating they were HIV-seropositive, while repeated serologic testing revealed no evidence of HIV infection. In all cases, the women were either quite angry or appeared surprised when told that they did not have HIV infection. A common denominator in all 4 women was a history of prolonged sexual, physical, or emotional abuse. Three of the 4 had been to other physicians, changing doctors as soon as the absence of HIV infection was established. Appropriate psychiatric support is an important aspect in care of these women, although it may not be accepted. All presentations of HIV infection should be confirmed either by identifying hard-copy data of HIV test results or by retesting all patients before evaluation and treatment of presumed HIV-related illnesses.

Assessment of respiratory system mechanics by artificial neural networks: an exploratory study

We evaluated 1) the performance of an artificial neural network (ANN)-based technology in assessing the respiratory system resistance (Rrs) and compliance (Crs) in a porcine model of acute lung injury and 2) the possibility of using, for ANN training, signals coming from an electrical analog (EA) of the lung. Two differently experienced ANNs were compared. One ANN (ANN(BIO)) was trained on tracings recorded at different time points after the administration of oleic acid in 10 anesthetized and paralyzed pigs during constant-flow mechanical ventilation. A second ANN (ANN(MOD)) was trained on EA simulations. Both ANNs were evaluated prospectively on data coming from four different pigs. Linear regression between ANN output and manually computed mechanics showed a regression coefficient (R) of 0.98 for both ANNs in assessing Crs. On Rrs, ANN(BIO) showed a performance expressed by R = 0.40 and ANN(MOD) by R = 0.61. These results suggest that ANNs can learn to assess the respiratory system mechanics during mechanical ventilation but that the assessment of resistance and compliance by ANNs may require different approaches.

HIV infection in families of HIV-positive and 'at-risk' HIV-negative women

Research of HIV infection within the family has focused upon sexual partners and vertical transmission. The scope of the problem of multiple infections and clustering of HIV among family members has, thus far, been less extensively explored. The objectives of this study are to investigate HIV infection in family members of HIV-seropositive and HIV-seronegative high-risk women and to consider the impact of multiple HIV infections within the family. Baseline data were evaluated from a prospective observational cohort of 871 HIV-seropositive and 439 seronegative at-risk women who are participants in a longitudinal study of HIV in women at four sites in the USA (Montefiore, Bronx, NY; Johns Hopkins University, Baltimore, MD; Brown University, Providence, RI; Wayne State University, Detroit, MI). Women were asked if anyone close to them had HIV/AIDS or had died from HIV/AIDS. Responses which included HIV-positive family members were analyzed. In the seropositive cohort, 35% (307/871) of the women had a family member with HIV infection. Of these 307 women, 38% reported having a sibling, 24% a husband and 27% had more than one family member with HIV/AIDS. Forty-nine per cent of Latina women, 34% of black women, and 21% of white women reported having a family member with HIV/AIDS. Using logistic regression analysis, we found that Latina and black women were significantly more likely than white women to have a sibling, extended family member or more than one family member with HIV/AIDS. Compared to seropositive women, seronegative high-risk women enrolled in this study appear equally likely to have an HIV-infected family member. In this study of HIV-positive women and high-risk seronegative women, a third reported having multiple family members with HIV infection, most often in a sibling. The high prevalence of HIV within families, particularly in the families of Latina and black women, mandates attention in planning both prevention and care.

Compensation for increase in respiratory workload during mechanical ventilation. Pressure-support versus proportional-assist ventilation

Variation in respiratory impedance may occur in mechanically ventilated patients. During pressure-targeted ventilatory support, this may lead to patient-ventilator asynchrony. We assessed the hypothesis that during pressure-support ventilation (PSV), preservation of minute ventilation (V E) consequent to added mechanical loads would result in an increase in respiratory rate (RR) due to the large reduction in tidal volume (VT). WITH proportional-assist ventilation (PAV), preservation of V E would occur through the preservation of VT, with a smaller effect on RR. We anticipated that this compensatory strategy would result in greater patient comfort and a reduce work of breathing. An increase in respiratory impedance was obtained by chest and abdominal binding in 10 patients during weaning from mechanical ventilation. V E remained constant in both ventilatory modes after chest and abdominal compression. During PSV, this maintenance of VE was obtained through a 58 +/- 3% increase in RR that compensated for a 29 +/- 2% reduction in VT. The magnitudes of the reduction in VT (10 +/- 3%) and of the increase in RR (14 +/- 2%) were smaller (p < 0. 001) during PAV. During both PSV and PAV, chest and abdominal compression caused increases in both the pressure-time product (PTP) of the diaphragm per minute (142.9 +/- 26.9 cm H(2)O. s/min, PSV, and 117.6 +/- 16.4 cm H(2)O. s/min, PAV) and per liter (13.4 +/- 2.5 cm H(2)O. s/L, PSV, and 9.6 +/- 0.7 cm H(2)O. s/L, PAV). These increments were greater (p < 0.001) during PSV than during PAV. The capability of keeping VT and V E constant through increases in inspiratory effort after increases in mechanical loads is relatively preserved only during PAV. The ventilatory response to an added respiratory load during PSV required greater muscle effort than during PAV.

Mechanical vs. alcohol epithelial removal during photorefractive keratectomy

PURPOSE

To assess whether a chemical debridement method for excimer laser photorefractive keratectomy may lead to better refractive and visual results than the standard method which involves the use of a blunt blade to scrape off the epithelium.

METHODS

Ninety-three eyes with a mean attempted correction of -5.72 +/- 2.47 D were debrided using a surgical microsponge after epithelial melting by 20% ethanol solution applied for 20 seconds, and treated by PRK. Results were compared to those from 97 eyes with a mean attempted correction of -6.05 +/- 2.46 D, deepithelialized using a Desmarres blade.

RESULTS

Debridement time was faster in the eyes where alcohol was used (P = .04). During a 6-month follow-up, we found no significant differences in refractive error, uncorrected, and spectacle-corrected visual acuity. However, haze rates at were lower (1 month, P = .04), and corneal regularity index was better (3 months, P = .01) in the eyes deepithelialized using alcohol.

CONCLUSIONS

Epithelial debridement using a 20% alcohol solution was faster to perform, and provided sharper edges and a smoother Bowman's layer surface than mechanical debridement. This may explain the better results in terms of haze and corneal regularity.

Time-course of impairment of respiratory mechanics after cardiac surgery and cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass (CPB) is associated with abnormalities of lung function characterized by an increase in static elastance of the respiratory system. We examined the following: a) the effects of CPB on the total inspiratory volume-pressure (V-P) relationship of the respiratory system; b) the relative contribution of the chest wall and lung to the impairment of respiratory system mechanics; and c) the time-course of such impairment.

DESIGN

Prospective, interventional study.

SETTING

Surgical and medical intensive care units in a teaching hospital.

PATIENTS

Eight adult patients scheduled for elective open heart surgery to correct valvular dysfunction.

INTERVENTIONS

V-P curves (interrupter technique) of the respiratory system were partitioned between the chest wall and lung by measurements of esophageal pressure. Measurements were obtained before sternotomy (control), immediately after, 4 hrs after, and 7 hrs after separation from CPB.

MEASUREMENTS AND MAIN RESULTS

Control V-P relationships of the respiratory system and lung showed lower inflection points (Pflex) at pressure values of 5.9+/-2.3 and 4.3+/-2.5 cm H2O, respectively. Immediately after and 4 hrs after separation from CPB, both curves had sigmoid shapes because of lower Pflex and formation of upper inflection (UIP) points. The pressures corresponding to the Pflex increased significantly (p < .001) by 56%+/-3% and 78%+/-4%, whereas the UIP corresponded to a pressure value of 42.34+/-8.5 and 35.6+/-7.8 cm H2O in the respiratory system and lung, respectively. A linear V-P relationship of the chest wall was observed during the control condition and after separation from CPB. Four hours later, no further increases in the pressure values corresponding to Pflex were observed on the inspiratory V-P curves of the respiratory system and lung, whereas the UIP occurred at a pressure of 35.6+/-9.1 and 29.7+/-8.4 cm H2O, respectively. A UIP was present on the V-P curve of the chest wall at a volume of 0.77+/-0.02 L. Seven hours after separation from CPB, the inspiratory V-P curves of the respiratory system, chest wall, and lung returned to normal.

CONCLUSIONS

Sternotomy and CPB produced immediate changes in lung mechanics. Chest wall mechanics were affected only 4 hrs after sternotomy. Seven hours after disconnection from CPB, all mechanics had returned to normal.

Impairment of lung and chest wall mechanics in patients with acute respiratory distress syndrome: role of abdominal distension

Recent data have suggested that the elastic properties of the chest wall (CW) may be compromised in patients with ARDS because of abdominal distension (4). We partitioned CW and lung (L) mechanics, assessed the role of abdominal distension, and verified whether the underlying disease responsible for ARDS affects the impairment of respiratory mechanics. Volume-pressure (V-P) curves (interrupter technique) were assessed in nine patients with surgical ARDS and nine patients with medical ARDS. Relative to nine patients undergoing heart surgery, V-P curves of the respiratory system (rs) and L of patients with surgical or medical ARDS showed a rightward displacement. V-P curves of the CW and the L showed an upward concavity in patients with medical ARDS and a downward concavity in patients with surgical ARDS. Although the CW and the abdomen (abd) V-P curves in patients with medical ARDS were similar to those obtained in patients undergoing heart surgery, they showed a rightward shift and a downward flattening in patients with surgical ARDS. In five of these patients, a reduction in static end-inspiratory pressure of the abd (69+/-4%), rs (30+/-3%), CW (41+/-2%), and L (27+/-3%) was observed after abdominal decompression for acute bleeding. Abdominal decompression therefore caused an upward and leftward shift of the V-P curves of the respiratory system, chest wall, lung, and abdomen. In conclusion we showed that impairment of the elastic properties of the respiratory system may vary with the underlying disease responsible for ARDS. The flattening of the V-P curve at high pressures observed in some patients with ARDS may be due to an increase in chest wall elastance related to abdominal distension. These observations have implications for the assessment and ventilatory management of patients with ARDS.

Effects of proportional assist ventilation on inspiratory muscle effort in patients with chronic obstructive pulmonary disease and acute respiratory failure

BACKGROUND

Acute respiratory failure may develop in patients with chronic obstructive pulmonary disease because of intrinsic positive end-expiratory pressure (PEEPi) and increased resistive and elastic loads. Proportional assist ventilation is an experimental mode of partial ventilatory support in which the ventilator generates flow to unload the resistive burden (flow assistance: FA) and volume to unload the elastic burden (volume assistance: VA) proportionally to inspiratory muscle effort, and PEEPi can be counterbalanced by application of external PEEP. The authors assessed effects of proportional assist ventilation and optimal ventilatory settings in patients with chronic obstructive pulmonary disease and acute respiratory failure.

METHODS

Inspiratory muscles and diaphragmatic efforts were evaluated by measurements of esophageal, gastric, and transdiaphragmatic pressures. Minute ventilation and breathing patterns were evaluated by measuring airway pressure and flow. Measurements were performed during spontaneous breathing, continuous positive airway pressure, FA, FA+PEEP, VA, VA+PEEP, FA+VA, and FA+VA+PEEP.

RESULTS

FA+PEEP provided the greatest improvement in minute ventilation (89 +/- 3%) and dyspnea (62 +/- 2%). The largest reduction in pressure time product per breath of the respiratory muscles and diaphragm (44 +/- 3% and 33 +/- 2%, respectively) also was observed during FA+PEEP condition. When VA was added to this setting, a reduction in respiratory rate (50 +/- 3%), an increase in inspiratory time (102 +/- 6%), and a further reduction in pressure time product per minute (65 +/- 2% and 64% for the respiratory muscles and diaphragm, respectively) was observed. However, values of pressure time product per liter of minute ventilation during FA+VA+PEEP did not differ with those observed during FA+PEEP condition. Worsening of patient-ventilator interaction and breathing asynchrony occurred when VA was implemented.

CONCLUSIONS

Application of PEEP to counterbalance PEEPi and FA to unload the resistive burden provided the optimal conditions in such patients. Ventilator over-assistance and patient-ventilator asynchrony was observed when VA was added to this setting. The clinical use of proportional assist ventilation should be based on continuous measurements of respiratory mechanics.

Asymptomatic large left-atrial ball thrombus. Secondary to mitral stenosis

We describe the very unusual case of a patient with a large, free-floating left-atrial thrombus secondary to severe mitral stenosis, in whom the peculiar symptoms and complications of a ball thrombus were absent. The patient's only symptom before the episode reported here was mild dyspnea, which was attributed to mitral stenosis. She experienced neither embolism nor syncope. While even her clinical signs did not indicate a left-atrial ball thrombus, both echocardiography and angiography showed a free-floating thrombus. Because of the risk of stroke and acute obstruction of the mitral valve, emergency surgery was performed upon diagnosis of the ball thrombus. The surgery, which consisted of removing the thrombus and replacing the mitral valve with a mechanical prosthesis, was uneventful. A computed tomographic brain scan prior to discharge did not detect any cerebral infarction.

Effects of positive end-expiratory pressure on right ventricular function in COPD patients during acute ventilatory failure

OBJECTIVE

To examine the effects of external positive end-expiratory pressure (PEEP) on right ventricular function in chronic obstructive pulmonary disease (COPD) patients with intrinsic PEEP (PEEPi).

DESIGN

Prospective study.

SETTING

General intensive care unit in a university teaching hospital.

PATIENTS

Seven mechanically ventilated flow-limited COPD patients (PEEPi = 9.7 +/- 1.3 cmH2O, mean +/- SD) with acute respiratory failure.

INTERVENTION

Hemodynamic and respiratory mechanic data were collected at four different levels of PEEP (0-5-10-15 cmH2O).

MEASUREMENTS AND RESULTS

Hemodynamic parameters were obtained by a Swan-Ganz catheter with a fast response thermistor. Cardiac index (CI) and end-expiratory lung volume (EELV) reductions started simultaneously when the applied PEEP was approximately 90% of PEEPi measured on 0 cmH2O (ZEEP). Changes in transmural intrathoracic pressure (PEEPi,cw) started only at a PEEP value much higher (120%) than PEEPi. The reduction in CI was related to a decrease in the right end-diastolic ventricular volume index (RVEDVI) (r = 0.61; p < 0.001). No correlation between CI and transmural right atrial pressure was observed. The RVEDVI was inversely correlated with PEEP-induced changes in EELV (r = -55; p < 0.001), but no with PEEPi,cw (r = -0.08; NS). The relationship between RVEDVI and right ventricular stroke work index, considered an index of contractility, was significant in three patients, i.e., PEEP did not change contractility. In the other patients, an increase in contractility seemed to occur.

CONCLUSIONS

In COPD patients an external PEEP exceeding 90% of PEEPi causes lung hyperinflation and reduces the CI due to a preload effect. The reduction in RVEDVI seems related to changes in EELV, rather than to changes in transmural pressures, suggesting a lung/heart volume interaction in the cardiac fossa. Thus, in COPD patients, application of an external PEEP level lower than PEEPi may affect right ventricular function.