Two-Year Outcomes After Minimally Invasive Surfactant Therapy in Preterm Infants: Follow-Up of the OPTIMIST-A Randomized Clinical Trial

Importance

The long-term effects of surfactant administration via a thin catheter (minimally invasive surfactant therapy [MIST]) in preterm infants with respiratory distress syndrome remain to be definitively clarified.

Objective

To examine the effect of MIST on death or neurodevelopmental disability (NDD) at 2 years' corrected age.

Design, Setting, and Participants

Follow-up study of a randomized clinical trial with blinding of clinicians and outcome assessors conducted in 33 tertiary-level neonatal intensive care units in 11 countries. The trial included 486 infants with a gestational age of 25 to 28 weeks supported with continuous positive airway pressure (CPAP). Collection of follow-up data at 2 years' corrected age was completed on December 9, 2022.

Interventions

Infants assigned to MIST (n = 242) received exogenous surfactant (200 mg/kg poractant alfa) via a thin catheter; those assigned to the control group (n = 244) received sham treatment.

Main Outcomes and Measures

The key secondary outcome of death or moderate to severe NDD was assessed at 2 years' corrected age. Other secondary outcomes included components of this composite outcome, as well as hospitalizations for respiratory illness and parent-reported wheezing or breathing difficulty in the first 2 years.

Results

Among the 486 infants randomized, 453 had follow-up data available (median gestation, 27.3 weeks; 228 females [50.3%]); data on the key secondary outcome were available in 434 infants. Death or NDD occurred in 78 infants (36.3%) in the MIST group and 79 (36.1%) in the control group (risk difference, 0% [95% CI, -7.6% to 7.7%]; relative risk [RR], 1.0 [95% CI, 0.81-1.24]); components of this outcome did not differ significantly between groups. Secondary respiratory outcomes favored the MIST group. Hospitalization with respiratory illness occurred in 49 infants (25.1%) in the MIST group vs 78 (38.2%) in the control group (RR, 0.66 [95% CI, 0.54-0.81]) and parent-reported wheezing or breathing difficulty in 73 (40.6%) vs 104 (53.6%), respectively (RR, 0.76 [95% CI, 0.63-0.90]).

Conclusions and Relevance

In this follow-up study of a randomized clinical trial of preterm infants with respiratory distress syndrome supported with CPAP, MIST compared with sham treatment did not reduce the incidence of death or NDD by 2 years of age. However, infants who received MIST had lower rates of adverse respiratory outcomes during their first 2 years of life.

Trial Registration

anzctr.org.au Identifier: ACTRN12611000916943.

Effect of Minimally Invasive Surfactant Therapy vs Sham Treatment on Death or Bronchopulmonary Dysplasia in Preterm Infants With Respiratory Distress Syndrome: The OPTIMIST-A Randomized Clinical Trial

IMPORTANCE

The benefits of surfactant administration via a thin catheter (minimally invasive surfactant therapy [MIST]) in preterm infants with respiratory distress syndrome are uncertain.

OBJECTIVE

To examine the effect of selective application of MIST at a low fraction of inspired oxygen threshold on survival without bronchopulmonary dysplasia (BPD).

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial including 485 preterm infants with a gestational age of 25 to 28 weeks who were supported with continuous positive airway pressure (CPAP) and required a fraction of inspired oxygen of 0.30 or greater within 6 hours of birth. The trial was conducted at 33 tertiary-level neonatal intensive care units around the world, with blinding of the clinicians and outcome assessors. Enrollment took place between December 16, 2011, and March 26, 2020; follow-up was completed on December 2, 2020.

INTERVENTIONS

Infants were randomized to the MIST group (n = 241) and received exogenous surfactant (200 mg/kg of poractant alfa) via a thin catheter or to the control group (n = 244) and received a sham (control) treatment; CPAP was continued thereafter in both groups unless specified intubation criteria were met.

MAIN OUTCOMES AND MEASURES

The primary outcome was the composite of death or physiological BPD assessed at 36 weeks' postmenstrual age. The components of the primary outcome (death prior to 36 weeks' postmenstrual age and BPD at 36 weeks' postmenstrual age) also were considered separately.

RESULTS

Among the 485 infants randomized (median gestational age, 27.3 weeks; 241 [49.7%] female), all completed follow-up. Death or BPD occurred in 105 infants (43.6%) in the MIST group and 121 (49.6%) in the control group (risk difference [RD], -6.3% [95% CI, -14.2% to 1.6%]; relative risk [RR], 0.87 [95% CI, 0.74 to 1.03]; P = .10). Incidence of death before 36 weeks' postmenstrual age did not differ significantly between groups (24 [10.0%] in MIST vs 19 [7.8%] in control; RD, 2.1% [95% CI, -3.6% to 7.8%]; RR, 1.27 [95% CI, 0.63 to 2.57]; P = .51), but incidence of BPD in survivors to 36 weeks' postmenstrual age was lower in the MIST group (81/217 [37.3%] vs 102/225 [45.3%] in the control group; RD, -7.8% [95% CI, -14.9% to -0.7%]; RR, 0.83 [95% CI, 0.70 to 0.98]; P = .03). Serious adverse events occurred in 10.3% of infants in the MIST group and 11.1% in the control group.

CONCLUSIONS AND RELEVANCE

Among preterm infants with respiratory distress syndrome supported with CPAP, minimally invasive surfactant therapy compared with sham (control) treatment did not significantly reduce the incidence of the composite outcome of death or bronchopulmonary dysplasia at 36 weeks' postmenstrual age. However, given the statistical uncertainty reflected in the 95% CI, a clinically important effect cannot be excluded.

TRIAL REGISTRATION

anzctr.org.au Identifier: ACTRN12611000916943.

Fat trajectory after birth in very preterm infants mimics healthy term infants

BACKGROUND

Infants born very preterm experience poor postnatal growth relative to intrauterine growth, but at term equivalent age, they have increased percentage body fat compared with infants born at term.

OBJECTIVES

The aim of this study was to assess body composition in very preterm infants born before 32 weeks postmenstrual age and to compare this with infants born at 32-36 weeks of gestation.

METHODS

Percentage fat, fat mass and fat-free mass were measured in 87 very preterm infants born <32 weeks of gestation and studied at 32-36 weeks and in 88 control infants born at 32-36 weeks of gestation and measured on days 2-5 postnatally.

RESULTS

At 32-36 weeks, very preterm infants were lighter and shorter, had significantly greater percentage fat and absolute fat mass and had a significantly lower absolute fat-free mass than the control group. The trajectory in percentage fat over increasing postnatal age in very preterm infants was closely aligned to that in term infants.

CONCLUSIONS

Infants born very preterm accumulate fat rapidly after birth and have a deficit in fat-free mass. Fat accumulation may be triggered by birth or associated events. If this rapid fat accretion is not taken into account, assessment of growth based on weight alone will underestimate the deficit in fat-free mass.

Canine carotid allograft changes after photochemotherapy and external polyester sheathing

BACKGROUND

The purpose of this study is to define and refine the changes in canine carotid allografts after photochemotherapy and polyester sheathing. Photochemotherapy with 8-methoxy psoralen (8MOP) and UVA (PUVA) was given alone or combined with intraluminal visible light (VL) 450 nm in proper dosages to speed the depopulation of endothelial (EC) and smooth muscle cells (SMC) and to modulate the immune response.

METHODS

Novel apparati were made for photochemotherapy of 19 right canine carotid arterial allografts with 19 paired untreated controls in the left carotid. External UVA and internal visible light (VL 450 nm) were used with 8-methoxy psoralen (8-MOP) as a sensitizer.

RESULTS

With moderate dosage of 8-MOP (1 microg/cc) and 2-4 J/cm2 of external UVA (PUVA), smooth muscle cells (SMC) disappeared faster from the media and fibroblasts (FB) appeared earlier in the adventitia of the treated right allografts, reducing but not eliminating the immune response. Intraluminal VL did not enhance the PUVA effect. At 68 days, treated and control allografts showed similar dimensions with subsided immune reactions. The media thickness was reduced from 0.38 mm to 0.18 mm and the host adventitia increased from 0.22 to 0.60 mm. Variable reactions peaked between two and three weeks and subsided after one month. All allografts remained open with canine carotid i.d.s of 2-3 mm and 80 to 100 cc/ minute arterial flows. Although the UVA dosage was moderate) similar doses sterilized log 7 of staph aureus cultures in saline. The allografts without smooth muscle showed moderate but stable cylindrical dilatation without spasm or stenosis and with an adequate adventitial buttress for a small vessel. A polyester sleeve around four treated grafts was inseparable from the allograft in less than 3 weeks and tolerated well over a 70-day period.

CONCLUSIONS

Biodegradable graft sheaths with bioerodible hydrogels with growth factors (FGF) for local delivery may provide a faster and more complete matrix remodeling for a superior conduit in the future.

Alarm settings for the Marquette 8000 pulse oximeter to prevent hyperoxic and hypoxic episodes

OBJECTIVE

To determine safe and appropriate alarm limits for the Marquette 8000 pulse oximeter to prevent hyperoxic and hypoxic episodes in neonates. It is necessary to define these limits for each brand of oximeter because of the variance in nonuser adjustable calibration algorithms used in pulse oximeters.

METHODOLOGY

Oxygen saturation values obtained from a Marquette 8000 pulse oximeter (SpO2) were compared with simultaneous arterial blood gas PaO2 values obtained from blood gas analysis, for 322 samples in 24 consecutive neonates (median 30 weeks' gestation).

RESULTS

In order to prevent 95% of hyperoxic episodes (PaO2 > 90 mmHg), the upper alarm limit was 95% SpO2. Similarly, to prevent 95% of hypoxic episodes (PaO2 < 40 mmHg), the lower alarm limit was 95% SpO2. A sensitivity lower than 95% had to be accepted to develop an alarm range which prevented both hyperoxic and hypoxic episodes. To maintain PaO2 values between 40 and 90 mmHg, an appropriate alarm range of 94-97% SpO2 (90% sensitivity, 28% specificity) was established.

CONCLUSIONS

The relative merits of high sensitivity versus high specificity should be considered when determining appropriate alarm limits. Alarm limits which represent a balance between sensitivity and specificity will minimise false alarms and provide a clinically practical range. It would be useful for this type of information to be available for each brand of oximeter, to assist the user in determining appropriate alarm settings.

The risk to public health of aeromonas in ready-to-eat salad products

Mesophilic Aeromonas spp. are isolated regularly from cases of gastrointestinal infection and have markers indicative of enteropathogenicity. Is aeromonas, which is present in a large proportion of ready-to-eat salads, actually a gastrointestinal pathogen? Isolates of mesophilic aeromonas from salads were characterised in terms of their ability to grow at refrigeration temperatures over the given shelf life and by the presence of markers of potential virulence. The major phenospecies present in salads, A.caviae, showed little enteropathogenic potential. Thirty-five per cent of aeromonas salad isolates are A.hydrophila or A.sobria, however, and all isolates tested had at least one marker of enteropathogenicity, including cytotoxin and haemolysin production, adherence to epithelial cells, and resistance to certain antibiotics Despite the presence of markers of enteropathogencity, the lack of epidemiological evidence of a link between infectious intestinal disease and the consumption of salads suggests that their contamination with aeromonas does not pose a significant risk to health in immunocompetent adults.

Optimisation of the protocol for detection of Aeromonas species in ready-to-eat salads, and its use to speciate isolates and establish their prevalence

Aeromonas spp. are detected in more than 500 cases of gastrointestinal infection each year in England and Wales. This study aimed to identify their prevalence in ready-to-eat salads, which are a potential source of aeromonas infection. The protocol for isolation of mesophilic Aeromonas spp. from salads was optimised. Using the improved method, Aeromonas spp were isolated from 19 of 25 samples (25 g) of ready-to-eat salad products. Aeromonas organisms were counted, isolates were identified to species level, and the effect of pH on colonisation of salads was assessed. Aeromonas was present at high levels in six salads (> or = 100 cfu/g). The major species present in salads was Aeromonas caviae, but A.hydrophila and A.sobria, which have more pathogenic potential, were also isolated. It is hoped that this study will help to assess the risk to public health of aeromonas in salads.

Modification of the standard method used in the United Kingdom for counting Escherichia coli in live bivalve molluscs

The standard method for counting Escherichia coli in live bivalve molluscs is labour intensive and takes three days to obtain a result. Modifications to the standard method were investigated in a collaborative trial conducted in five centres. No significant difference was found between results based on the presence of acid at 24 hours (h) in first stage tests and those based on the presence of acid and gas after 48 h (standard method). The use of the chromogenic medium BCIG (5-bromo-4-chloro-3-indolyl-beta-D glucuronide) agar incubated at 44 degrees C to confirm first stage tests was also found to give equivalent results to conventional confirmation tests. The preferred, modified method removes the presence of gas as a criterion of detection, uses a chromogenic agar medium to confirm the presence of E. coli, and gives results within 48 h. A distribution of simulated samples and selected strains of E. coli to other laboratories using the PHLS external quality assurance scheme for shellfish found no significant difference between results obtained by the standard and modified methods.

Single-lung transplantation in a patient with cystic fibrosis and an asymmetric thorax

We report metachronous single-lung transplantation for cystic fibrosis after contralateral pneumonectomy. Kyphoscoliosis and mediastinal shift required careful donor-lung sizing with computed tomography and was not dependent on typical parameters. Severe reperfusion injury was treated with nitric oxide, C1-esterase inhibitor, and continuous venovenous hemodialysis. The patient was extubated on the fifth postoperative day and is alive and well. We conclude that single-lung transplantation after contralateral pneumonectomy for patients with cystic fibrosis and an asymmetric chest and evident lung volume mismatch may be an acceptable functional therapeutic option.

Management of malignant esophagotracheal fistulas with airway stenting and double stenting

Prognosis of inoperable or recurrent esophageal carcinoma is, at best, poor. Once an esophagotracheal fistula has developed, the overall condition of the patient declines rapidly. Aspiration pneumonia and severe coughing are common. The introduction of esophageal tubes does not always seal the fistula sufficiently and may compromise the airway causing stridor and dyspnea. In 30 patients (25 male, 5 female; age 23 to 74 years; mean, 56 years) with very large fistulas and airway problems, we inserted an airway stent (Dynamic) (n = 12) or an esophageal tube combined with a Dynamic airway stent (n = 18) with the aim of sealing the fistula and restoring patency of the airway and GI passage. The tracheobronchial Dynamic stent was chosen because its slightly concave, flexible posterior silicone membrane adapts ideally to the convex esophageal tube. The stents were well tolerated and significantly improved the quality of life. Of 30 patients, 16 could breathe and swallow unimpaired until shortly before their death. Moderate complaints persisted in five patients, dysphagia in eight patients, and dyspnea in one patient. Mean survival time in the double stent group was significantly greater (110 days) than in the airway stent-only group (24 days) or comparable groups in the literature treated with esophageal tubes only. We conclude that carefully selected patients can benefit from double stenting of esophagus and airways.

Mitochondrial encephalomyopathy: a rare genetic cause of sensorineural hearing loss

A 44-year-old man with a documented 12-year history of progressive sensorineural hearing loss developed a generalized tonic-clonic seizure followed by a visual field deficit and apraxia. Six months later he developed a peripheral neuropathy and muscle fatigue followed by a slowly progressive aphasia and cortical blindness as well as increased seizure activity. A computed tomography scan showed bilateral basal ganglion calcification. The serum lactate level was elevated at 3.4 mEq/dL. A muscle biopsy enabled the diagnosis of mitochondrial myopathy. This disorder is presented as an unusual cause of progressive sensorineural hearing loss in adults.

Postoperative disruption of an internal prong-type caval filter--a case report

A prong-type caval filter fractured and disintegrated within 4 months after its implantation in a 21-year-old woman. The fragments and the disrupted filter were removed surgically and the vena cava was plicated. Seven similar cases were found in the literature. Possible etiologic factors and measures to avoid this complication are discussed.

Culture media for the isolation and enumeration of pathogenic Vibrio species in foods and environmental samples

The genus Vibrio now includes a large number of species. Clear evidence is only available for the aetiological role of V. cholerae, V. vulnificus and V. parahaemolyticus in foodborne diseases. Until recently, V. cholerae serogroup 0:1 was accepted as the cause of epidemic cholera. However, the designation of outbreaks of diarrhoeal diseases caused by V. cholerae 0:139 as clinical cholera has lead to renewed interest in Non 0:1 serogroups of V. cholerae. A wide range of enrichment and selective media for the isolation of vibrios has been developed. These media are reviewed with respect to their ability to recover and differentiate the target vibrios. Alkaline peptone water (APW) remains the recommended enrichment medium for vibrios in parallel with either salt polymyxin broth (SPB) or glucose teepol (or sodium dodecylsulphate) salt broth (GTSB) when tests for V. parahaemolyticus are required. Thiosulphate citrate bile salt agar (TCBS) in parallel with polymyxin mannose tellurite (PMT) or sodium dodecylsulphate polymyxin sucrose agar (SPS) are the recommended selective plating media.

The efficacy of amrinone or adrenaline on low cardiac output following cardiopulmonary bypass in patients with coronary artery disease undergoing preoperative beta-blockade

We examined 20 patients undergoing coronary bypass grafting for coronary artery disease with NYHA classifications of II and III who had been treated with beta-blocking agents. Patients were randomised for administration of either adrenaline (0.1 microgram/kg/min) or amrinone (bolus 1 mg/kg, continuous infusion of 5-10 micrograms/kg/min), if following cardiopulmonary bypass their cardiac index was < 2.4 L/min/m2 with normal peripheral resistance and normal or increased right- or left-ventricular filling pressures. Over a period of 1 hour, the hemodynamic parameters mean arterial pressure (MAP), cardiac index (CI), heart rate (HR), coronary perfusion pressure (CPP), total peripheral resistance (TPR), as well as the pressure-work index (PWI) were registered or calculated. By means of a coronary sinus catheter myocardial arterio-venous oxygen content difference (AVDO2cor), myocardial blood flow (MBF), using the thermodilution method, and myocardial oxygen consumption (MVO2) could be measured or calculated. Simultaneously, arterial and myocardial lactate concentrations and, using the arterio-venous lactate ratio, myocardial lactate extraction or production were quantified. Using a transseptal approach, the left-ventricular pressure curve was measured and used to differentiate for myocardial contractility (dp/dtmax). Following induction of anesthesia and after cardiopulmonary bypass, plasma levels of the used beta-blocking agent were determined. Both substances caused a significant increase in myocardial contractility, with adrenaline showing a more potent effect than amrinone. Both substances caused a significant increase in CI with a mild increase in HR. Amrinone caused a significant drop in TPR, while MAP remained practically constant.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of Clostridium perfringens and its enterotoxin in cases of sporadic diarrhoea

AIMS

To determine the incidence of sporadic and apparently non-food related diarrhoea associated with Clostridium perfringens enterotoxin.

METHODS

Enzyme linked immunosorbent assay (ELISA) and reversed phase latex agglutination (RPLA) were used to detect C perfringens enterotoxin in faecal specimens from 818 sporadic cases of diarrhoea.

RESULTS

C perfringens enterotoxin was identified as a cause of sporadic diarrhoea in 56 of 818 (6.8%) cases. Diarrhoea was prolonged (three days or more) in most cases. Ages ranged from 3 months to 89 years, although most patients were over 60 years of age.

CONCLUSIONS

These results suggest that C perfringens may be a cause of sporadic cases of diarrhoea when causes such as food consumption or cross-infection are absent, particularly in the elderly.

Counter-current chromatography of black tea infusions

Counter-current chromatography using a multilayer coil planet centrifuge, with solvent system ethyl acetate-butanol-water, permits the separation of black tea infusions into fractions which include pure SII and a mixture of SI and SIa thearubigins. Good resolution of several components of the infusion may be achieved in elution times of 1 to 2 h. The appearance of chromatograms is altered on decaffeinating the infusion. The effect of stationary phase composition is considered. Resolution of the peaks improves with butanol content.

Functional analysis of cryopreserved veins. Preliminary report

Functional comparisons of cryopreserved and fresh canine vein endothelium, smooth muscle, and connective tissue were performed. Morphometric analysis of saphenous vein endothelium revealed no significant loss of endothelial integrity as a result of cryopreservation. Endothelial cell culture revealed similar numbers of clonogenic intimal cells from cryopreserved and fresh saphenous, cephalic, and jugular veins. Smooth muscle function was assessed by measurement of the isometric force generated by vein rings in response to norepinephrine, serotonin, and potassium chloride. There was no significant difference in the dose responses of cryopreserved and fresh saphenous veins to the reagents tested. Similar results were obtained for the cephalic and jugular vein experiments with norepinephrine. The maximum tensions generated in response to norepinephrine were 52% of fresh control segments. Connective tissue function was assessed by quantitation of 3H-proline incorporation. The results indicate that cryopreserved veins retained approximately 43.5% of values of fresh vein collagen synthesis. Finally, eight cryopreserved cephalic vein autografts were placed as femoral artery grafts and were removed electively after 1 to 8 weeks. All grafts were patent. Both light and electron microscopy demonstrated that the cryopreserved veins remained intact in vivo and that arteriolization occurred as described for fresh autografts in the literature. In conclusion, cryopreserved veins retain much of their cellular and tissue functions on thawing. Transplantation of cryopreserved veins suggests that cryopreservation does not change the sequence of histologic events associated with the use of autologous fresh vein as an arterial substitute.

Health literature for parents of children with cerebral palsy

This study examined the use of and need for written educational material by the parents of 41 children with cerebral palsy, aged between five and 63 months. After their initial counselling, the majority felt that they needed written information. The parents of 31 children attempted to find suitable books or pamphlets, but in 13 cases they failed to do so or found the material unsatisfactory. A significant association was found between reading material which the parents found satisfactory and their knowledge about the basic features of cerebral palsy.

Congenital dermoid cyst of the anterior tongue

Thirteen cases of “dermoid” cysts of the tongue have been reported in the literature, whereas only three of these have been histologically of the dermoid variety.1 We report the fourth known case of pathologically proven dermoid type cyst of the tongue. The embryology is reviewed.

Evaluation of endoscopic sclerotherapy of esophageal varices in children

Sixteen children (3.5-14.7 years) with portal hypertension and variceal hemorrhage were treated by direct endoscopic variceal sclerotherapy. Follow-up clinical and endoscopic evaluations have been carried out over a 1-6-year period (mean, 2.3 years). Prior to sclerotherapy, three patients had undergone unsuccessful surgical approaches, and the mean transfusional requirement from the time of the first hemorrhage was 12.3 units of blood per child per year for those with extrahepatic portal vein obstruction (n = 10) and 3.8 units for those with primary liver disease. Following sclerotherapy, transfusional requirements were significantly reduced in both groups, to 1.8 units and 2.2 units (85% and 43% reduction, respectively). Re-bleeding in four patients was due to the occurrence of gastric varices. One patient with extrahepatic portal hypertension has required subsequent shunt surgery for this complication, 5 years after sclerotherapy. Two patients have died, one with cystic fibrosis and hemorrhage from gastric varices and one from liver failure due to progressive biliary cirrhosis. Complications of sclerotherapy included transient retrosternal pain (eight occasions), esophageal ulceration with bleeding (n = 1) and esophageal stricture (n = 1). We conclude that sclerotherapy is an effective technique in obliterating esophageal varices and reducing the risk of hemorrhage in children with portal hypertension, with an acceptably low complication rate. We favor its use over more invasive surgical measures for control of acute and recurrent variceal hemorrhage, particularly for cases of extrahepatic portal hypertension in which a favorable natural history is likely.

Biologic fate of valves in reversed and nonreversed arterial vein grafts

The cusps of valve-bearing segments of canine cephalic, femoral, and jugular veins were completely divided and were used in interposition grafts in the femoral and carotid arteries in the nonreversed position. Three control grafts had intact valves in the reversed position, and one control graft in the reversed position had division of the leaflets. Nine grafts were studied up to 2 months postoperatively with gross and microscopic observations. The cusp tissue, which shrinks immediately after complete division, disappears very early in the postoperative period in the reversed and nonreversed positions. Two reversed intact valves were still grossly microscopically normal 5 and 7 weeks postoperatively. The complete disappearance of the divided valve with a nonreversed coronary graft 101/2 months postoperatively has been documented at autopsy for the first time in a human subject. The significance of these findings and the superiority of the valveless nonreversed autogenous vein graft in clinical cardiovascular surgery has been discussed.

Early experience with in situ saphenous vein grafts for severe ischemia of the lower extremity

Based upon this group of 35 patients with a variety of vascular lesions, it would appear that the in situ saphenous vein technique is certainly, at least, a viable alternative to standard bypass techniques. It has been applied with equally encouraging results by several surgeons in a variety of clinical settings, all using the procedure for the first time in a learning phase. This technique may become the procedure of choice for the treatment of occlusive disease of the lower extremity in this difficult and challenging group of patients.

Computed tomography of the normal larynx

A computed tomographic analysis of normal laryngeal anatomy was undertaken using cadaver larynxes. This was part of a larger project in which patients with laryngeal carcinoma were routinely evaluated in the computed tomographic (CT) body scanner. The appearance of normal laryngeal anatomy had to be delineated before disease processes of the larynx were evaluated, and this was accomplished using a computed tomographic technique with 5-mm slice thicknesses and a 3-mm overlap. The scan slices were then compared with anatomic sections taken at the same levels. The comparisons demonstrate an ideal level of accuracy that can be approached in the in-vivo larynx only with use of the latest-generation scanners. However, CT scanning is of immediate usefulness in the diagnosis of laryngeal pathology.

Myocardial perfusion and metabolism at normothermic and hypothermic levels

Changes in intramyocardial carbon dioxide tension (Pco2) and arterial oxygen tension (Po2) were recorded in dogs with a mass spectrometer after temporary occlusion of the aorta and the proximal part of the anterior descending coronary artery at normothermic and hypothermic levels. Patterns of hypoxic and hypercapnic changes and their recovery were favorably modified with moderate hypothermia. Deep levels of hypothermia seemed to enhance this protective effect and progressively slow the myocardial metabolism. Occlusion of the proximal part of the anterior descending coronary artery for 30 minutes had a regional effect similar to the general myocardial changes recorded after aortic clamping, while the posterior myocardial probe showed stable control values. These data support previous studies showing that moderate hypothermia halves the oxygen consumption and doubles the "safe" period of anoxic arrest.