Bradyarrhythmias and Laparoscopy: A Prospective Study of Heart Rate Changes with Laparoscopy

Cardiac arrhythmias are a common complication of laparoscopy. Brady-arrhythmias (including asystole) may be life-threatening. The recent introduction of new shorter-acting muscle relaxants (atracurium and vecuronium), with their lack of vagolytic activity, may exacerbate this situation. At the Royal Women's Hospital there have been several episodes of severe bradyarrhythmias and/or asystole associated with these relaxants. This study evaluated heart rate changes in 49 women during laparoscopy: 47% of patients had arrhythmias, 30% of these being bradyarrhythmias. Nearly all the episodes occurred during carbon dioxide insufflation or with traction on pelvic structures. The life-threatening nature of this phenomenon should be understood by all anaesthetists and gynaecologists engaged in laparoscopic procedures.     

Idiopathic cavovarus and lateral ankle instability: recognition and treatment implications relating to ankle arthritis

Hindfoot malalignment and chronic lateral ankle instability may lead to degenerative ankle arthritis. We retrospectively analyzed 10 patients with 13 cavovarus feet. None of the patients had underlying neurologic disorders. All patients presented with a history consistent with chronic lateral ankle instability, clinically with cavovarus feet, and radiographically with varying degrees of varus talar tilt and ankle arthritis. Ankles with severe degenerative change were fused. The ankles with mild or moderate change underwent calcaneal osteotomy with lateral ligament reconstruction and/or dorsiflexion osteotomy of the first metatarsal. A quantitative radiographic Coleman block test was utilized to aid in the preoperative planning of the calcaneal and metatarsal osteotomies. All patients had correction of preoperative deformity and resolution of pain and instability. Recognition of the association between cavovarus and chronic ankle instability and degenerative ankle arthritis may be important in developing the appropriate treatment strategy in this patient population.     

Predicting the response to recombinant human growth hormone in Turner syndrome: KIGS models

A mathematical model for predicting the growth response in patients with Turner syndrome who received growth hormone (GH) therapy was developed by analysing data from KIGS, the Pharmacia & Upjohn International Growth Database. A Model for year 1 of GH therapy explained 46% of the variability of the growth response, with GH dose being the most important of the predictors of height velocity. In years 2-4 of therapy, height velocity during the previous year was the most important predictor, suggesting that an individual's initial response to GH may determine the height outcome of treatment. Additional treatment with oxandrolone. The predictions in all 4 years were highly accurate, as indicated by the low error SDs. However, relatively low predictive power ( R ) during years 2-4 of treatment suggests the models are missing other parameters that would explain more of the variability of the growth response. These growth prediction models could help clinicians to design individualized treatment regimens, provide realistic expectations of therapy outcomes, and adjust treatment on the basis of detected differences between observed and predicted height velocities.     

Retinopathy of prematurity in infants < 32 weeks'' gestation at birth in New South Wales in 1993 and 1994

OBJECTIVE: To study the incidence and severity of retinopathy of prematurity (ROP) in infants < 32 weeks' gestation. DESIGN: Review of the records maintained in the New South Wales Neonatal Intensive Care Unit Study (NICUS) database on infants admitted to the neonatal intensive care units (NICU) in NSW from 1 January 1993 to 31 December 1994. RESULTS: In the more premature infants, 23-26 weeks' gestation, 65% developed ROP (102 of 157 examined for ROP). Forty-four infants (28%) developed severe ROP (Stage >/= 3 ROP), 19 infants (12.1%) required cryo/laser therapy and one infant (0.6%) in this group had a retinal detachment. One hundred and fifty-seven of 159 surviving infants (98.7%) were examined for ROP. In the infants 27-28 weeks' gestation, 38.3% developed ROP (103 of 269 examined for ROP). Fifteen infants (5.6%) developed severe ROP, seven infants (2. 6%) required cryo/laser therapy for threshold ROP and three infants (1.1%) in this group had a retinal detachment. Two hundred and sixty-nine of 299 surviving infants (90%) were examined for ROP. In the infants 29-31 weeks' gestation, 10.8% developed ROP (48 of 443 examined for ROP). Six infants (1.4%) developed severe ROP, one infant (0.2%) required cryo/laser therapy for threshold ROP and no infant in this group had a retinal detachment. However, only 443 of 681 surviving infants (65.1%) in this group were examined for ROP. Of the four infants with detached retinas, one was a 25 week gestation infant weighing 840 g, two were 27 weeks' gestation weighing 960 and 980 g and one infant was a 28 week gestation infant weighing 620 g. No infant developed Stage 5 ROP. CONCLUSION: In the more mature infants 29-31 weeks' gestation, the rate of ROP is low, although severe ROP still occurs. However, only 65.1% of these infants were examined for ROP and we should be diligent in screening for ROP in the sicker infants in this group. The incidence of severe ROP as well as the rate of cryo/laser therapy in premature infants 23-26 weeks' in NSW has not changed since the increases seen in the early 1990s. Retinal detachment also occurs in the infants 27-28 weeks' gestation and it is important that all these infants are screened for ROP.     

MR technology: effect of even-echo rephasing on calculated T2 values and T2 images

In multiple spin-echo image sequences of blood flow, the "even-echo" phenomenon produces an absolute increase in signal magnitude from first- to second-echo images of normal vessels harboring slow flow. Distinguishing this from the apparent relatively high signal intensity seen on second-echo images in pathologic foci of stationary tissue is important to the diagnostician. Selected case material containing two tissue types was reviewed retrospectively: tissues known to harbor slow flow, such as normal veins and venous sinuses and vascular malformations, and tissues that have long transverse (T2) relaxation times and appear as intense structures on second-echo images, such as neoplasms, infarcts, and regions of demyelination. Calculations of T2 parameters were made by computer for defined regions of interest. T2 images were also generated. Visual inspection of the acquired images did not reliably distinguish increased intensity due to even-echo rephasing from the relative changes between adjacent tissues seen on second-echo images. More definitive differentiation of the even-echo phenomenon was provided by calculated values of T2 and computer-synthesized T2 images representing acquired intensity data of two-echo sequences. The synthesized images were especially useful when stationary tissue with lengthened T2 values was adjacent to or in proximity to vessels or vascular lesions. A five spin-echo image sequence was valuable for separating slow flow from stationary tissue by a technique of synthesizing T2-difference images using three consecutive echoes.     

Chemotherapy and delivery in the treatment of primary brain tumors

Malignant astrocytomas are aggressive neoplasms with a dismal prognosis despite optimal treatment. Maximal resective surgery is traditionally complemented by radiation therapy. Chemotherapy is typically used on patients with tumor recurrence, when their functional status is congruent with further treatment. The classic agents used are nitrosoureas, but temozolomide is gradually taking a more prominent role recently. New agents, biological modifiers, are increasingly used in clinical trials in an effort to affect the intrinsic biologic aberrations harboured by tumor cells. These drugs comprise differentiation agents, anti-angiogenic agents, matrix-metalloproteinase inhibitors and signal transduction inhibitors, among others. The issue of chemotherapy delivery is also crucial. Classically, agents are administered either intravenously or orally. In an effort to circumvent the obstacle imposed by the blood-brain barrier, investigators are actively working on more invasive methods of delivery, namely intra-arterial infusion with or without blood-brain barrier disruption or direct intra-cerebral administration, with clysis or drug-impregnated wafers. This article reviews the standard cytotoxic agents that have been used to treat malignant astrocytomas, and the different combination regimen offering promise. In addition, recent advances with biological modifiers are also discussed, along with alternate methods to deliver the agents more efficiently across the blood-brain barrier.     

Ontogeny of central rhythm generation in chicks and rodents

Recent studies help in understanding how the basic organization of brainstem neuronal circuits along the anterior-posterior (AP) axis is set by the Hox-dependent segmentation of the neural tube in vertebrate embryos. Neonatal respiratory abnormalities in Krox20(-/-), Hoxa1(-/-) and kreisler mutant mice indicate the vital role of a para-facial (Krox20-dependent, rhombomere 4-derived) respiratory group, that is distinct from the more caudal rhythm generator called Pre-B?tzinger complex. Embryological studies in the chick suggest homology and conservation of this Krox20-dependent induction of parafacial rhythms in birds and mammals. Calcium imaging in embryo indicate that rhythm generators may derive from different cell lineages within rhombomeres. In mice, the Pre-B?tzinger complex is found to be distinct from oscillators producing the earliest neuronal activity, a primordial low-frequency rhythm. In contrast, in chicks, maturation of the parafacial generator is tightly linked to the evolution of this primordial rhythm. It seems therefore that ontogeny of brainstem rhythm generation involves conserved processes specifying distinct AP domains in the neural tube, followed by diverse, lineage-specific regulations allowing the emergence of organized rhythm generators at a given AP level.     

The economic impact of a partnership-measurement model of disease management: Improving Cardiovascular Outcomes in Nova Scotia (ICONS)

Improving Cardiovascular Outcomes in Nova Scotia (ICONS) was a five-year, community partnership-based disease-management project that sought, as a primary goal, to improve the care and outcomes of patients with heart disease in Nova Scotia. This program, based on a broad stakeholder partnership, provided repeated measurement and feedback on practices and outcomes as well as widespread communication and education among all partners. From a clinical viewpoint, ICONS was successful. For example, use of proven therapies for the target diseases improved and re-hospitalization rates decreased. Stakeholders also perceived a sense of satisfaction because of their involvement in the partnership. However, the universe of health stakeholders is large, and not many have had an experience similar to ICONS. These other health stakeholders, such as decision-makers concerned with the cost of care and determining the value for cost, might, nonetheless, benefit from knowledge of the ICONS concepts and results, particularly economic analyses, as they determine future health policy. Using budgetary data on actual dollars spent and a robust input-output methodology, we assessed the economic impact of ICONS, including trickle-down effects on the Canadian and Nova Scotian economies. The analysis revealed that the $6.22 million invested in Nova Scotia by the private sector donor generated an initial net increase in total Canadian wealth of $5.32 million and a global net increase in total Canadian wealth of $10.23 million, including $2.27 million returned to the different governments through direct and indirect taxes. Thus, the local, provincial and federal governments are important beneficiaries of health project investments such as ICONS. The various government levels benefit from the direct influx of private funds into the publicly funded healthcare sector, from direct and indirect tax revenues and from an increase in knowledge-related employment. This, of course, is in addition to the clinical benefits associated with the partnership-measurement disease-management model. Because of their uniquely simultaneous roles as beneficiary and major resource provider, the public payer can play an early and active role in such partnerships to enhance its efficiencies and increase the likelihood of sustainability if the original concepts are proven of value.