Use of propofol infusion in Australian and New Zealand paediatric intensive care units

Despite the risk of propofol infusion syndrome, a rare but often fatal complication of propofol infusion in ventilated children and possibly adults, propofol infusion remains in use in paediatric intensive care units (PICU). This questionnaire study surveys the current pattern of use of this sedative infusion in Australian and New Zealand PICUs. Thirty-three of the 45 paediatric intensive care physicians surveyed (73%), from 12 of the 13 intensive care units, returned completed questionnaires. The majority of practitioners (82%) use propofol infusion in children in PICU, the main indication being for short-term sedation in children requiring procedures. 39% of respondents consider propofol infusion useful in ventilated children requiring longer-term sedation. 67% of paediatric intensivists use maximum infusion doses that may be considered dangerously high (> or = 10 mg/kg/h). Nineteen per cent use propofol infusion for prolonged periods (> 72 hours). A smaller proportion (15%) of respondents indicate that they may use both higher doses and prolonged periods of infusion, a practice likely to lead to a greater chance of serious adverse events. Knowledge of local protocols for the use of propofol infusion is associated with a significantly greater level of monitoring for possible adverse events. We suggest that national guidelines for the use of propofol infusion in children should be developed. These should include clear indications and contraindications to its use, a maximum dose rate and maximum period of infusion, with a ceiling placed on the cumulative dose given and clearly stated minimum monitoring requirements.

A comparison of three scoring systems for mortality risk among retrieved intensive care patients

AIMS

To assess the impact of two paediatric intensive care unit retrieval teams on the performance of three mortality risk scoring systems: pre-ICU PRISM, PIM, and PRISM II.

METHODS

A total of 928 critically ill children retrieved for intensive care from district general hospitals in the south east of England (crude mortality 7.8%) were studied.

RESULTS

Risk stratification was similar between the two retrieval teams for scores utilising data primarily prior to ICU admission (pre-ICU PRISM, PIM), despite differences in case mix. The fewer variables required for calculation of PIM resulted in complete data collection in 88% of patients, compared to pre-ICU PRISM (24%) and PRISM II (60%). Overall, all scoring systems discriminated well between survival and non-survival (area under receiver operating characteristic curve 0.83-0.87), with no differences between the two hospitals. There was a tendency towards better discrimination in all scores for children compared to infants and neonates, and a poor discrimination for respiratory disease using pre-ICU PRISM and PRISM II but not PIM. All showed suboptimal calibration, primarily as a consequence of mortality over prediction among the medium (10-30%) mortality risk bands.

CONCLUSIONS

PIM appears to offer advantages over the other two scores in terms of being less affected by the retrieval process and easier to collect. Recalibration of all scoring systems is needed.

Antioxidant protection against iron in children with meningococcal sepsis

OBJECTIVE

To assess antioxidant protection against iron-catalyzed reactive oxygen species in meningococcal sepsis and to establish whether severity of illness is related to deficiencies in these antioxidant systems.

DESIGN

Prospective, controlled study.

SETTING

Pediatric intensive care unit of a postgraduate teaching hospital.

PATIENTS

Twenty children aged 6 months to 15 yrs (median, 5 yrs) with meningococcal septic shock were studied. Paired convalescent samples taken 8-10 wks after discharge were available in nine children.

INTERVENTIONS

Routine management for meningococcal sepsis.

MEASUREMENTS AND MAIN RESULTS

Patients were classified for disease severity using the Glasgow Meningococcal Septicaemia Prognostic Score. Paired acute and convalescent samples were compared. Transferrin level (1.77 +/- 0.08 g/L) and total iron-binding capacity (46.2 +/- 2.0 microM) were significantly decreased in acute patients compared with paired convalescent samples (2.85 +/- 0.10 g/L and 74.4 +/- 2.5 microM, respectively; p <.0001). The iron saturation of transferrin was significantly increased in acute disease (36.9% +/- 2.5%) compared with convalescence (18.8% +/- 1.5%; p =.0003). Iron-binding antioxidant protection was not significantly different in acute (81.4% +/- 1.7%) and paired convalescent samples (85.6% +/- 2.5%; p =.54). However, patients with more severe meningococcal septicemia (GMSPS, >10; n = 12) had significantly diminished protection (77.5% +/- 2.4%) compared with less severe disease (87.1% +/- 1.6%; p =.0028), and there was a significant correlation between disease severity and iron-binding antioxidant protection (R =.48; p =.00067) in acute disease. Paired ceruloplasmin levels were available in six patients and were decreased in acute disease (0.29 +/- 0.02 g/L) compared with convalescence (0.40 +/- 0.04 g/L), although not statistically significant (p =.076). However, there was a significant correlation between plasma ceruloplasmin and disease severity (Pearson product moment correlation, p =.038) in the acute patients. Iron-oxidizing antioxidant assays were performed in four paired samples and were diminished in acute patients (53.3 +/- 4.4%) compared with convalescence (67.8 +/- 3.2%; p =.015). Acute samples demonstrated a significant relationship between iron-oxidizing antioxidant protection and both disease severity (r =.30; p =.012) and plasma ceruloplasmin levels (r =.48; p =.00067).

CONCLUSIONS

Children with meningococcal septicemia exhibit abnormal plasma iron chemistry and decreased protection against iron-catalyzed oxidative damage. Such deficiencies correlate with disease severity.

Clinical scoring systems in meningococcal disease

Scoring systems used in meningococcal disease have been developed and validated to predict death or severity of illness in cohorts of patients, usually in the setting of intensive care. When using these scores, it is important to remember that any individual's score is only of limited value in prognosticating about that individual patient and can be misleading (1). The accuracy of any score is determined by how well its estimated pattern of mortality compares with that observed in the score's developmental cohort, rather than in individual patients. Scores cannot be considered interchangeable; different scores, comprised of different sets of variables to arrive at the probability of mortality, may arrive at the same overall aggregate risk of mortality in a population of patients with meningococcal disease, despite individual estimates within this cohort of patients differing widely between scores. The ability of a score to predict death for patients who die and survival for those that live is best-described by the area under the receiver operator characteristic (ROC) curve (2). This curve is a plot of sensitivity versus "(1 -specificity)", i.e., the true-positive to false-positive fractions, at different decision thresholds. The greater the discriminative ability of a test, the closer the area under the curve comes towards 1.0, where the true-positive fraction is 1.0 or 100% (perfect specificity) and the false-positive fraction is 0 (perfect sensitivity). No score, however, has sufficient accuracy for individual prognostication and the use of scores in this way is inappropriate for clinical practice or research (3).

Overexpression of H ferritin and up-regulation of iron regulatory protein genes during differentiation of 3T3-L1 pre-adipocytes

The role of iron-dependent oxidative metabolism in protecting the oxidable substrates contained in mature adipocytes is still unclear. Because differentiation increases ferritin formation in several cell types, thereby leading to an accumulation of H-rich isoferritins, we investigated whether differentiation affects iron metabolism in 3T3-L1 pre-adipocytes. To this aim, we evaluated the expression of the genes coding for the H and L ferritin subunits and for cytoplasmic iron regulatory protein (IRP) during the differentiation of 3T3-L1 cells in adipocytes induced by the addition of isobutylmethylxanthine, insulin, and dexamethasone. Differentiation enhanced ferritin formation and caused overexpression of the H subunit, thus altering the H/L subunit ratio. Northern blot analysis showed increased levels of H subunit mRNA. A gel retardation assay of cytoplasmic extract from differentiated cells, using an iron-responsive element as a probe, revealed enhanced an RNA binding capacity of IRP1, which correlated with the increase of IRP1 mRNA. The observed correlation between differentiation and iron metabolism in adipocytes suggests that an accumulation of H-rich isoferritin may limit the toxicity of iron in adipose tissue, thus exerting an antioxidant function.

Oxalomalate, a competitive inhibitor of aconitase, modulates the RNA-binding activity of iron-regulatory proteins

We investigated the effect of oxalomalate (OMA, alpha-hydroxy-beta-oxalosuccinic acid), a competitive inhibitor of aconitase, on the RNA-binding activity of the iron-regulatory proteins (IRP1 and IRP2) that control the post-transcriptional expression of various proteins involved in iron metabolism. The RNA-binding activity of IRP was evaluated by electrophoretic mobility-shift assay of cell lysates from 3T3-L1 mouse fibroblasts, SH-SY5Y human cells and mouse livers incubated in vitro with OMA, with and without 2-mercaptoethanol (2-ME). Analogous experiments were performed in vivo by prolonged incubation (72 h) of 3T3-L1 cells with OMA, and by injecting young mice with equimolar concentrations of oxaloacetate and glyoxylate, which are the precursors of OMA synthesis. OMA remarkably decreased the binding activity of IRP1 and, when present, of IRP2, in all samples analysed. In addition, the recovery of IRP1 by 2-ME in the presence of OMA was constantly lower versus control values. These findings suggest that the severe decrease in IRP1 RNA-binding activity depends on: (i) linking of OMA to the active site of aconitase, which prevents the switch to IRP1 and explains resistance to the reducing agents, and (ii) possible interaction of OMA with some functional amino acid residues in IRP that are responsible for binding to the specific mRNA sequences involved in the regulation of iron metabolism.

Long-term results of heart valve replacement with bileaflet prostheses

Bileaflet cardiac prostheses (St. Jude, CarboMedics, Duromedics, Bicarbon, Jyros) have shown a low incidence of complications and good haemodynamic performance. In the last twelve years, 783 bileaflet prostheses were implanted in 690 patients at our Institution. The population of our study comprises 591 bileaflet prostheses (418 CarboMedics, 124 St. Jude, 49 Bicarbon) implanted in the mitral (MVR) (n = 305) or aortic (AVR), (n = 286) position. The follow-up study evaluated 292 male and 295 female patients with age ranging from 13 and 79 years (mean 50.4 +/- 14.7 years). Hospital mortality was 6.6%. Follow-up was 97% complete, with 1822 +/- 33 patient/years and a mean follow-up of 37 months (range 1 to 144 months). Twelve years actuarial freedom from complication according to prosthetic site were calculated as follows (linearized rates in parentheses): late mortality AVR 97.6% +/- 0.6% (2.3%), MVR 96% +/- 0.5% (2.1%); thrombosis AVR 100%, MVR 96% +/- 0.9% (0.8%); embolism AVR 97% +/- 0.5% (1.5%), MVR 96.6% +/- 0.7% (1.8%). Global freedom from anticoagulant-related haemorrhage was 95% +/- 1.2% (2.3%) and 94.5% +/- 0.7% (2.2%) following AVR, 94 +/- 0.6% (2.1%) following MVR. The difference of the haemorrhagic risk for prosthetic site was not significant (p > 0.05). Functional improvement was confirmed by the low postoperative NYHA functional class. According to our results, cumulative experience with bileaflet valves has shown very good long-term results in term of low rate of complication, long-term survival and quality of life.

Delayed diagnosis of Kawasaki disease presenting with massive lymphadenopathy and airway obstruction

Images

[A case of Veratrum poisoning]

A poisoning from a Veratrum album infusion mistaken for Gentiana lutea is described. Confusion between these two plants can easily occur because they are very similar, although flowers and disposition of leaves allow their botanic determinat: V. album leaves are alternate and flowers are white, while G. lutea leaves are opposite and flowers yellow. The poisoning involves gastrointestinal (pyrosis, vomiting) and cardiocirculatory systems (bradyarrhy-thmias, A-V dissociation, vasodilatation) Atropine is the drug of choice.

Submitral left ventricular aneurysm. Report of 2 surgical cases

Submitral left ventricular aneurysm most commonly occurs among the black population. Nevertheless, this lesion has been described among whites. We report 2 cases of submitral left ventricular aneurysm that we treated successfully by surgery. Case 1 is that of a 52-year-old Brazilian black man with a submitral left aneurysm and mitral incompetence. Case 2 is that of a 25-year-old white man with a history of recurrent stroke; his echocardiographic study showed a small submitral left ventricular aneurysm. Due to the growing incidence of submitral left ventricular aneurysm among the white population, we emphasize the importance of a targeted echocardiographic study in all patients with a history of embolic episodes in the absence of apparent risk factors for embolism.

Stentless fresh pulmonary homograft in mitral position

We report the implantation of a fresh, stentless pulmonary homograft in the mitral position as an attempt to treat the 2nd recurrence of prosthetic endocarditis in a 66-year-old man. The postoperative course was uneventful; early postoperative transesophageal echocardiography showed a competent valve with a gradient of 4.2 mmHg. Fifteen months postoperatively, transthoracic echocardiography showed a good functioning homograft with a competent valve and no recurrence of endocarditis.

Acute postoperative block of mechanical prostheses: incidence and treatment

Acute intermittent postoperative block of mechanical prostheses is a rare and life-threatening complication; its incidence and treatment are not well defined. Between January 1975 and June 1991, 2839 mechanical prostheses were implanted using the same technique: mattress suture for mitral valve replacement and simple suture for aortic valve replacement. Prosthetic block occurred in eight patients: four following mitral valve replacement and four after aortic valve replacement. The blocked prosthesis was always a tilting disc valve (five Sorin, two Björk-Shiley and one Medtronic). The event occurred over a time interval of 6-48 h (mean(s.d.) 17.3 (15.6)h). All patients having mitral valve replacement needed emergency prosthetic replacement. In aortic valve replacement, reoperation was necessary in two patients; the disc block disappeared in the others. All patients are alive with a follow-up ranging between 3 and 168 (mean 32.5) months. No structural failure was found in explanted prostheses leading to a diagnosis of extrinsic block. The overall incidence of this complication was 0.28% (eight of 2839); 0.24% (four of 1645) for mitral valve replacement and 0.33% (four of 1194) for aortic valve replacement respectively (n.s.). It was exclusively related to tilting disc valves (0.44%; eight of 1830) versus ball and bileaflets valve (0 of 1009). In mitral valve replacement reoperation on patients is mandatory; in aortic valve replacement patients the left ventricular pressure itself can overcome the prosthetic block. Attention should be paid to valve excision and suture techniques as tilting disc prostheses are more vulnerable to extrinsic block. Furthermore, their use is contraindicated in redo operations and mitral valve replacement with total or partial preservation of mitral apparatus.

Prosthetic valve obstruction: thrombolysis versus operation

An acute obstruction is a life-threatening complication of mechanical valve prostheses, and is caused by the formation of fresh clot or fibrous tissue overgrowth, or both. Accurate selection of the most appropriate treatment for a particular patient is mandatory. From January 1991 to July 1992, 28 cases of prosthetic thrombosis were managed. Twenty patients underwent surgical treatment, with one operative death, and 8 patients were treated with thrombolysis using recombinant tissue-type plasminogen activator (rt-PA). The criteria for using thrombolysis were (1) the recent onset of symptoms, (2) transesophageal echocardiographic evidence of clots on the valve or cardiac chambers, and (3) preserved disc excursions. All patients who underwent thrombolysis had mechanical valves (two bileaflets, four tilting discs, and two ball valves); seven valves were in the mitral position and one was in the aortic. Symptoms of obstruction consisted of cardiac failure in 6 cases or thromboembolism in 5, or both. The mean interval between the onset of symptoms and the initiation of thrombolysis was 81 +/- 65 hours. After infusion of the rt-PA, normal valve function was restored in all patients, as documented by transesophageal echocardiography. No deaths or neurologic complications occurred; there was one episode of minor peripheral embolism. Thrombolysis using rt-PA may be the appropriate treatment in patients with primary thrombosis of mechanical valves, thereby avoiding the operation-related risks.

[Empty sella syndrome in obese patient with cushingoid features. Description of a clinical case]

The authors describe a case of a female obese patient with cushingoid habitus who was not suffering from Cushing's syndrome or disease but from empty sella syndrome. The authors emphasize the importance of a systematic search for possible causes of obesity, especially if it joins with a particular habitus.

[A new ventilation method: the laryngeal mask]

A size 3 laryngeal mask was used in 20 patients who underwent elective general surgery. It consists of a silicon tube attached to mask which must be inserted into the hypopharynx and then inflated. No curarisation nor laryngoscopy is needed. Operations were performed in assisted or spontaneous ventilation, with good airway patency and absence of coughing, secretions and sore throat. In 2 cases introduction of the mask failed. Technique, advantages and problems related to its use are described.

[Prosthetic valve endocarditis]

The Authors report their experience of the surgical treatment of cardiac prosthetic endocarditis. Between September 1974 and December 1988, 2,796 cardiac prostheses were implanted. An endocarditis in the follow-up of 23 patients involving 27 prostheses was diagnosed. The operative mortality was high in patients with mitral prosthetic endocarditis; in patients with infected aortic prosthesis operative mortality was low, but there was a high incidence of recurrence. The Authors emphasize the difficulty of diagnosis and the importance of the surgical treatment for eradication of the infection and for resolution of the haemodynamic defect.

[Intermediate echocardiographic follow-up of a new model of pericardial prosthesis (Pericarbon)]

The paper deals with the echocardiographic medium-term follow-up of 11 patients fitted with a Sorin Pericarbon bioprosthesis. Four hundred and ninety-seven biological prostheses were implanted during the period January 1975 to December 1988, of which 22 (4.42%) were Pericarbon. The first 11 patients (mean age 55.3 years) who underwent isolated mitral or aortic valve replacement were included in the study. In 5 patients the bioprosthesis was implanted in mitral site, and in 6 in aortic. Post-operative 2D-Doppler echocardiographic tests revealed good hemodynamic performance indices, even in small calibre vessels, and the absence of early malfunctions. Although the number of patients studied is small, the absence of early malfunctions and the technical innovations of the bioprosthesis make it preferable to other pericardiac prostheses.

Alterations of the endoalveolar surfactant after surgery with extracorporeal circulation

In 10 patients who required extracorporeal circulation (ECC) during surgery, we studied the damage induced by surgery to the pulmonary surfactant and the effectiveness of ambroxol in preventing changes in the phospholipid pool. There were 5 control patients and 5 patients who were given 1 g/day of ambroxol on the 4 days prior to and the 4 days after surgery. To follow changes in phospholipid concentrations, bronchoalveolar lavage (BAL) was performed before surgery and 24 h and 8 days after ECC. Phospholipids were assayed in the BAL liquid by two-dimensional thin-layer chromatography. There were marked decreases in total phosphorus and quantitative alterations of individual phospholipid species in the surfactant of the control group, but not in the patients treated with ambroxol.

Clinical results after cardiac valve replacement with the Sorin prosthesis. A 6-year experience

The mechanical valve produced by Sorin is a modified tilting disc device. Between March 1979 and November 1985, 763 Sorin prostheses were implanted in 710 patients. The study has been restricted to 504 isolated mitral or aortic valves. There were 238 females and 266 males whose ages ranged from 2 to 71 years (mean 43.8). Follow-up is 99.23% and covers 1045 patient-years. No structural failure has been observed. In the aortic position, 282 Sorin prostheses were implanted with the large orifice orientated towards the right coronary sinus. Hospital mortality was 5% (14/282). Actuarial survival at 78 months was 94.68% +/- 1.6% with a linearized mortality rate of 1.7% patient-years. There were 11 late deaths (9 valve-related and 2 non valve-related). The linearized rate of occurrence of embolic events was 0.32 patient-years (2/268). Actuarial survival complication-free at 78 months was 90.88% +/- 2.83%. Preoperatively, 19.8% patients were in NYHA class II, 68.5% in III and 11.7% in IV; postoperatively, 79.3% patients were in NYHA class I, 19.5% in II and 1.2% in III. In the mitral position, 222 Sorin prostheses were implanted with the large orifice orientated anteriorly in 46 patients (group 1) and posteriorly-in 176 patients (group 2). Hospital mortality was 4.5% (10/222). Actuarial survival at 66 months was 93.25% +/- 2.1% with a linearized mortality rate of 2.8 patient-years. There were 12 late deaths (9 valve-related and 3 non valve-related). The 66-month actuarial freedom from embolic events was 95.8% +/- 1.89% with a linearized rate of occurrence of 1.44 patient-years.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolapse of the "floppy" aortic valve as a cause of aortic regurgitation. A clinico-morphologic study

A clinico-pathologic study was performed in 25 patients undergoing aortic valve replacement because of regurgitation, caused by myxoid degeneration of the valve leaflets. Associated cardiac anomalies were floppy mitral valve (2 cases), floppy mitral valve and idiopathic hypertrophic subaortic stenosis (1), left atrial myxoma (1), and aortic coarctation at the isthmus (1). Three patients died (2 immediately and 1 on the 30th postoperative day). Pathological studies of the explanted valves showed deformities characterized by redundant thin leaflets which appeared soft and gelatinous. On histologic examination the fibrous layer of the leaflets was seen to be infiltrated by myxomatous tissue. Echocardiography showed the aortic root to be dilated in 13 patients and normal in the others. In those with normal aortic root, the histological examination of aortic wall disclosed minimal cystic medial necrosis in two cases. In contrast, more severe forms of cystic medial necrosis were evident in all patients having a dilated aortic root. Aortic valve replacement was performed in all cases. It was accompanied by a Bentall procedure (1 case), repair of ascending aorta dissection (2), replacement of the ascending aorta (1), mitral valve replacement (2), mitral valve replacement and apico-ascending aorta conduit (1) and excision of a left atrial myxoma (1). Our experience suggests that prolapse of the aortic valve due to floppy leaflets is a common degenerative disease which is generally associated with noninflammatory aortic root degeneration. This, together with aortic root dilatation, contributes to valve insufficiency. Nevertheless, the disease, when isolated (with normal aortic root), is liable in itself to produce aortic regurgitation. The need for early diagnosis is stressed, so as to be able to perform valve replacement.

Intermediate term evaluation of Starr-Edwards ball valves in the mitral position

The Model 6120 ball valve prosthesis introduced in 1965 is still strongly supported as a mitral valve substitute in many centers around the world. A current reassessment of the performance of this prosthesis is therefore pertinent to current medical practice. In this institution since 1974, 227 Starr-Edwards caged ball valves have been implanted in the mitral position during isolated valve replacement. Two models of caged ball valves were used concurrently: the silastic ball valve in 108 patients (48%) and the composite strut "tract" valve in 119 (52%). Hospital mortality was 7%, and 8-year survival (standard error) was 74 (6%), with 100% follow-up, documenting 752 total patient-years. No late deaths were known to be valve related, and there were no cases of prosthetic thrombosis. The actuarial estimate of patients free from thromboembolism at 8 years was 89 (4%) with a linearized rate of 1.3% per year. At the most recent follow-up, 95% of the patients were in the New York Heart Association (NYHA) Classes I or II. These good results were partly due to an awareness at operation of ventricular outflow tract size requirements and to strict control of postoperative anticoagulation. We conclude that the Starr-Edwards ball valve is the mitral valve of choice in the young patient who is able to take anticoagulation drugs and has a left ventricular outflow tract of satisfactory size.

[A case of Hodgkin's disease with primary splenic localization]

In this work a case of splenic Hodgkin's disease is reported. It was diagnosed only by a second exploratory laparotomy. There was no involvement of lymph nodes, other organs or systems. Hodgkin's disease was histologically associated with sarcoid-like granulomas and the significance of this association is discussed. In addition to splenectomy, this patient was treated with chemotherapy.