A simple eye model for practicing indirect ophthalmoscopy and retinal laser photocoagulation

Purpose

To describe a simple and inexpensive model eye that allows lifelike simulation of indirect ophthalmoscopy and retinal photocoagulation.

Methods

A 60 D examination lens, a bulb syringe, foam poster-board, a manila folder, a hobby knife, a fine pair of scissors, a glue gun, and a 2.5 cm square Optos color fundus photograph printed at 1200 dpi resolution on glossy photographic paper were used to create a model eye.

Results

This model produces a high-quality, inverted, and aerial image that closely simulates clinical indirect ophthalmoscopy. Pupil size and retinal pathology can be easily changed. Binocular indirect laser photocoagulation can also be simulated, because white laser burns will appear on the glossy inkjet photograph.

Conclusions

Binocular indirect ophthalmoscopy and indirect laser photocoagulation are technically challenging diagnostic and therapeutic techniques. This simple and easy-to-build eye model allows for lifelike simulation of indirect ophthalmoscopy and indirect laser retinal photocoagulation.

FROSTED BRANCH ANGIITIS IN METHIMAZOLE-INDUCED ANTINEUTROPHIL CYTOPLASMIC ANTIBODY-POSITIVE VASCULITIS

PURPOSE

To describe an unusual case of frosted branch angiitis that developed in a patient with acute onset systemic vasculitis possibly triggered by the antithyroid medication methimazole.

METHODS

We conducted a thorough review of the medical records of a 16-year-old female patient who presented with frosted branch angiitis. During the initial hospital admission, the patient underwent an extensive systemic workup to determine the etiology of her disease and ophthalmologic testing including fundus photographs and fluorescein angiography.

RESULTS

Our patient presented with a unilateral acute onset loss of vision, whose fundus examination revealed the pathognomonic features of frosted branch angiitis. Extensive systemic workup revealed an antineutrophilic cytoplasmic antibody-positive vasculitis, possibly triggered by methimazole.

CONCLUSION

This case is the first reported frosted branch angiitis associated with a drug-induced antineutrophilic cytoplasmic antibody-positive vasculitis triggered by methimazole.

Postoperative complications following vitrectomy for proliferative diabetic retinopathy with sew-on and noncontact wide-angle viewing lenses

BACKGROUND AND OBJECTIVE

To compare the occurrence of vitreous hemorrhages and retinal detachments following vitrectomy surgery with sew-on lenses to a noncontact wide-angle lens system.

PATIENTS AND METHODS

Retrospective review of 180 patients who underwent primary vitrectomy for proliferative diabetic retinopathy. The occurrence of persistent and recurrent vitreous hemorrhages as well as postoperative retinal detachments in the two groups was determined.

RESULTS

There was no statistically significant difference in the occurrence of persistent vitreous hemorrhages between the sew-on (55%) and the wide-angle (42%) lens systems (P = 0.099). Likewise, recurrent vitreous hemorrhages were similar in both the sew-on (15%) and the wide-angle (17%) lens systems (P = 0.838). However, postoperative detachments were more frequent in the sew-on group (9%) than in the wide-angle (1%) group (P = 0.046).

CONCLUSION

In patients with proliferative diabetic retinopathy, using a wide-angle noncontact lens system significantly reduced the incidence of postoperative retinal detachments, but not persistent or recurrent vitreous hemorrhages.

Poor postnatal weight gain: a risk factor for severe retinopathy of prematurity

PURPOSE

This study aimed to investigate the relationship between rate of postnatal weight gain and severity of retinopathy of prematurity (ROP).

METHODS

All infants (n = 111) screened for ROP at a single tertiary intensive care nursery over a 2-year period with an estimated gestational age of 30 weeks or less and follow-up to at least 42 weeks' postconception were included. The authors performed a retrospective review of records and statistical analysis of risk factors for ROP using multivariate analysis.

RESULTS

Infants with severe (stage 3 or greater) ROP gained an average 10.9 g/kg per day in the first 6 weeks of life, compared to a mean of 9.6 g/kg per day for those with mild or no ROP (P =.04). By multiple regression, which included birth weight, gestational age, and 9 other reported risk factors, there was an association between rate of postnatal weight gain and severity of ROP (P =.02). By stepwise regression, 4 variables were associated with ROP severity: estimated gestational age at birth (P =.002), rate of postnatal weight gain (P = .0002), volume of transfused erythrocytes (P =.0001), and culture-proven sepsis (P = .02).

CONCLUSION

Poor postnatal weight gain is a risk factor for the development of severe (stage 3 or greater) ROP. Ophthalmologists should take note of those infants who gain less than 50% of their birth weight in the first 6 weeks of life.

Prognostic significance of vascular dilation and tortuosity insufficient for plus disease in retinopathy of prematurity

BACKGROUND

Plus disease, one of the most important prognostic indicators in retinopathy of prematurity (ROP), is designated as present or absent. A grading system based on comparison with standard, high-quality color photographs may be useful to more accurately describe the spectrum of vascular dilation and tortuosity preceding plus disease, but it is of practical value only if it has prognostic significance. We hypothesized that grading of "pre-plus" vascular changes can identify eyes at risk for progression to vision-threatening ROP.

METHODS

Video clips of posterior pole images captured at the examination closest to 33 weeks' postconceptional age of 32 infants screened during an 18-month period were randomized. Two masked examiners viewed and graded the images in comparison with standard photographs representative of 5 distinct grades of retinal vascular dilation and tortuosity. A case-control design was used to compare the incidence of progression to stage 3 ROP, development of plus disease, and requirement of laser treatment between infants with normal posterior poles and those judged to have early dilation and tortuosity insufficient for plus disease.

RESULTS

Of the 8 patients with mild vascular dilation and tortuosity insufficient for plus disease, 5 (63%) eventually required laser treatment, 4 (50%) later developed stage 3 ROP, and 5 (63%) progressed to plus disease. Of the 24 patients with normal posterior poles, none required laser treatment, 2 (8%) developed stage 3 ROP, and none progressed to plus disease. The group with mild vascular dilation and tortuosity had a significantly higher incidence of progression to laser treatment (P =.0003), stage 3 ROP (P =.027), and plus disease (P =.0003).

CONCLUSIONS

Early vascular dilation and tortuosity judged insufficient for plus disease have prognostic significance in the early course of ROP. A grading system that uses standard, high-quality color photographs representing the spectrum of "pre-plus" vascular changes has potential utility in both the clinical and research settings.

Oxacillin-resistant Staphylococcus aureus endophthalmitis after ganciclovir intraocular implant

PURPOSE

To describe a patient who developed oxacillin-resistant Staphylococcus aureus endophthalmitis after insertion of a ganciclovir intraocular implant.

METHOD

Case report.

RESULTS

A 42-year-old man with acquired immunodeficiency syndrome (AIDS) and a history of cytomegalovirus retinitis was admitted with right-sided eye pain and decreased visual acuity 10 days after receiving a second ganciclovir intraocular implant in the right eye. A therapeutic vitrectomy, right eye, was performed on the day of admission. A vitreal tap produced frank pus and white, fluffy debris. Cultures of the vitreal fluid grew oxacillin-resistant S aureus, sensitive only to vancomycin, rifampin, and trimethoprim/sulfamethoxazole. The patient was successfully treated with removal of both ganciclovir implants in the right eye and a 4-week course of vancomycin and rifampin. However, the infection left the patient blind in the infected eye.

CONCLUSION

Bacterial endophthalmitis is an infrequent but serious complication of the ganciclovir intraocular implant.

Entoptic perimetry screening for central diabetic scotomas and macular edema

OBJECTIVE

The aim of this study was to compare entoptic perimetry, using conventional television, to Amsler grid and patient-reported visual loss for the detection of functional diabetic maculopathy and macular edema.

DESIGN

Observational case series.

PARTICIPANTS

A single eye from each of 104 consecutive patients with diabetes in an academic retina clinic.

INTERVENTION

Each eye was screened by Amsler grid, entoptic perimetry, and Humphrey 10-2 threshold visual field testing (HVF 10-2; Humphrey Instruments Inc., San Leandro, CA) in random order. Eyes were then examined clinically.

MAIN OUTCOME MEASURES

The presence or absence of new visual decline since the patient's last clinical examination, the presence or absence of central visual field abnormalities using an Amsler grid, entoptic perimetry, HVF 10-2, and the presence or absence of clinically significant macular edema (CSME).

RESULTS

The sensitivities and specificities for the detection of central diabetic scotomas as evidenced by HVF 10-2 abnormalities were: subjective impression, 31 of 90 eyes (34.4%) and 11 of 14 eyes (78.6%); Amsler grid, 29 of 90 eyes (32.2%) and 13 of 14 eyes (92.9%); and entoptic perimetry, 58 of 90 eyes (64.4%) and 11 of 14 eyes (78.6%). Entoptic perimetry was statistically more sensitive than both subjective impression (P < 0.001) and Amsler grid (P < 0.001), but the specificities were statistically indistinguishable. The sensitivities and specificities for the detection of CSME were: subjective impression, 6 of 24 eyes (25.0%) and 52 of 80 eyes (65.0%); Amsler grid, 9 of 24 eyes (37.5%) and 59 of 80 eyes (73.8%); and entoptic perimetry, 17 of 24 eyes (70.8%) and 44 of 80 (55.0%) eyes. These results are also statistically significant, with entoptic perimetry being more sensitive and less specific than both subjective impression (P = 0.007 and P = 0.011, respectively) and Amsler grid (P = 0.008 and P < 0.001, respectively) in this subset of patients.

CONCLUSIONS

Entoptic perimetry is 87% more sensitive than the subjective impression of visual decline (P < 0.001) and 100% more sensitive than Amsler grid (P < 0.001) for the detection of central scotomas in diabetic patients. For the detection of CSME, entoptic perimetry is 183% more sensitive than subjective impression (P = 0.007) and 89% more sensitive than Amsler grid (P = 0.008). Hence, entoptic perimetry, performed using conventional television, has the potential to be an effective, inexpensive, and widespread adjunct to surveillance examinations for the early detection of diabetic maculopathy.

The importance of fluorescein angiography in planning laser treatment of diabetic macular edema

OBJECTIVE

To test the hypothesis that pretreatment fluorescein angiography (FA) is not necessary for effective laser treatment of patients with clinically significant diabetic macular edema (CSME).

DESIGN

Prospective, randomized, controlled treatment simulation.

PARTICIPANTS

Six fellowship trained retina specialists.

INTERVENTION

The authors compared the ability of four retina specialists (observers) to plan laser treatment with and without the use of FA. One hundred consecutive cases of CSME were selected, each case consisting of a stereo pair of color photographs and a corresponding fluorescein angiogram. These cases were first read by two retina specialists who reached consensus on a treatment plan for each case (standard map). Each of the 4 observers reviewed 50 of these cases on 2 occasions and plotted 2 sets of treatment maps, 1 set created with and 1 without the aid of FA. Each observer's 100 treatment maps were graded for accuracy by comparing them to the corresponding standard maps. The role of FA in improving the accuracy of treatment maps was evaluated using logistic regression analysis to control for different observers, different cases, and different posterior pole characteristics.

MAIN OUTCOME MEASURES

Accuracy was defined as the proportion of standard treatment correctly treated by the observer.

RESULTS

For the observers as a group, the use of FA improved treatment planning accuracy from 49% to 54.5% (P = 0.02); however, there was significant interobserver variation in performance (P < 0.001). Treatment planning accuracy without and with FA was as follows: observer 1, 40.8% and 40.2%; observer 2, 49.8% and 72%; observer 3, 56.1% and 59.5%; and observer 4, 49.2% and 46.4%.

CONCLUSION

The use of FA improves the accuracy of treatment planning for CSME. The authors' study supports the use of FA in laser treatment of patients with CSME.

Corneal epithelial defects following vitrectomy surgery using hand-held, sew-on, and noncontact viewing lenses

PURPOSE

To compare the incidence of corneal epithelial defects following vitrectomy surgery with Charles hand-held infusion lenses, Landers sew-on lenses, and the Oculus BIOM noncontact lens system.

METHODS

We performed a retrospective chart review of 234 patients who underwent initial vitrectomy surgery by one surgeon. We determined the presence and duration of postoperative epithelial defects and identified predisposing factors.

RESULTS

There were more corneal epithelial defects noted postoperatively in eyes with hand-held infusion lenses (23.8%) compared with eyes with sew-on lenses (8.6%; P = 0.010) and eyes with noncontact lenses (0%; P < 0.001). There were also more defects in sew-on versus noncontact lenses (P = 0.014). Diabetic patients had more postoperative epithelial defects with hand-held infusion lenses (32.1 %) than with sew-on lenses (8.8%; P = 0.011) or with noncontact lenses (0%; P < 0.001). The average operative time for patients with epithelial defects (169 minutes) was longer than for patients without defects (117 minutes) (P < 0.001). The risk of these defects remained significant after controlling for both length of surgery and diabetes status.

CONCLUSIONS

Corneal epithelial defects were more common after vitrectomy surgery using hand-held infusion lenses than after surgery using sew-on lenses and did not occur with the noncontact lens system. In addition, reducing the operative time may independently reduce the risk of epithelial defects, regardless of lens type.

Significance of isolated neovascular tufts ("popcorn") in retinopathy of prematurity

BACKGROUND

The significance of isolated neovascular tufts ("popcorn") occurring in association with stage 2 retinopathy of prematurity (ROP) has not been studied.

METHODS

We retrospectively reviewed the clinical courses and outcomes of all patients with zone II, stage 2 ROP with popcorn examined over the past 3 years at one institution. Eyes with zone I disease, plus disease, or stage 3 at the initial appearance of popcorn were excluded. The study group was compared with a control group of patients of similar birth weight and gestational age with zone II, stage 2 ROP without popcorn.

RESULTS

Popcorn first appeared at a mean age of 36.4 (+/- 2.2) weeks after conception in 26 patients. Of these, 17 patients (65%) progressed to stage 3, 10 (38%) had plus disease, 6 (23%) reached threshold, and 9 (35%) required laser treatment. Of 19 control patients, 4 (21%) progressed to stage 3, 1 (5%) had plus disease, 1 (5%) reached threshold, and 1 (5%) required laser treatment. The popcorn group had a significantly higher incidence of progression to stage 3 (p < 0.005), plus disease (p < 0.025), and laser treatment (p < 0.025). All eyes of both groups had complete regression of disease.

CONCLUSIONS

The presence of popcorn significantly increases the risk that an eye with zone II, stage 2 ROP will progress to stage 3, develop plus disease, and require laser treatment. Patients with popcorn and coexistent mild vascular dilation or tortuosity insufficient for plus disease are at particularly high risk for disease progression.

Delayed vitreous hemorrhage after placement of a ganciclovir implant for cytomegalovirus retinitis

PURPOSE

To report a massive vitreous hemorrhage in a 26-year-old woman that occurred approximately 6 weeks after she received a ganciclovir implant.

METHOD

Case report.

RESULTS

The cytomegalovirus retinitis was inactivated after uncomplicated insertion of a ganciclovir implant. Approximately 6 weeks later, the patient was examined for sudden painless visual loss caused by a dense vitreous hemorrhage.

CONCLUSION

Sustained-release ganciclovir implants may be associated with delayed vitreous hemorrhage.

Observer sensitivity to retinal vessel diameter and tortuosity in retinopathy of prematurity: a model system

BACKGROUND

Abnormally increased diameter and tortuosity of retinal blood vessels in the posterior pole, or "plus disease," is recognized as a powerful predictor of poor outcome in eyes with retinopathy of prematurity (ROP). Although the diagnosis of plus disease depends upon the examiner's ability to examine retinal blood vessels, the ability of the human observer to identify changes in retinal blood vessel diameter and tortuosity accurately has not been studied.

METHODS

Using computer-aided analysis of fundus photographs from eyes with a wide range of ROP severity, we generated tracings of posterior pole blood vessels which varied by quintiles of mean vessel diameter and tortuosity. Subjects (23 naive and 12 expert observers) ranked groups of tracings in order of increasing mean vessel diameter and tortuosity. These ranking tests were performed on tracings derived from the same fundus and tracings derived from distinct fundi. In a similar fashion, subjects also compared one designated standard fundus tracing with 25 distinct fundus tracings.

RESULTS

Vessel diameter was assessed correctly more often than vessel tortuosity, both among similar (> 99% vs 92% of the time, respectively, P < 0.001), or among distinct (88% vs 78% of the time, respectively, P < 0.001) fundus images. The mean vessel diameter and tortuosity of 25 distinct fundus images were correctly ranked versus a standard image in 89% of attempts. Assessments of increments in vessel diameter and tortuosity were independent. Naive and expert subjects performed indistinguishably on all tests.

CONCLUSIONS

Intelligent human observers have considerable ability to discern clinically relevant increments in blood vessel diameter and tortuosity. This ability may facilitate standardization in the diagnosis of plus disease in ROP.

Clinical course and systemic correlates of retinopathy of prematurity in quintuplets

PURPOSE/METHODS

We studied clinical correlates of retinopathy of prematurity in four surviving quintuplets with similar low birth weights and gestational age of 27 weeks. Prospective serial ophthalmoscopic examinations and retrospective chart analysis were used.

RESULTS/CONCLUSIONS

Retinopathy of prematurity varied among the neonates from stage 2 with total regression to threshold progressing to retinal detachment. Severity of eye disease correlated with duration of mechanical ventilation and of parenteral nutrition, as well as frequency of hypoglycemia and of hypercapnia. Poor outcome correlated inversely with weight gain.

Indirect ophthalmoscope perimetry in patients with retinal detachment or retinoschisis

PURPOSE/METHODS

We evaluated visual field testing, using indirect ophthalmoscopy, in patients with retinal detachment or retinoschisis. While performing ophthalmoscopy, we projected a shadow onto the schisis or detachment by holding a scleral depressor on the observer's side of the condensing lens. A response was recorded as positive if the patient saw the shadow.

RESULTS/CONCLUSION

In all 20 detachment eyes, compared to zero of 12 schisis eyes, the response was positive. Indirect ophthalmoscope perimetry can help distinguish retinoschisis from retinal detachment.

The ocular effects of intralenticular iron foreign bodies in rabbits

Optimal treatment of intralenticular metallic foreign-body injuries remains controversial, especially in patients with clear lenses and good vision. Using 20 rabbit eyes, we examined the cataractogenic potential of intralenticular iron and its effects on the retina. Iron wire implanted into the lenses of 12 rabbit eyes caused cataracts in every eye within 4 weeks. However, after 4 1/2 weeks, none of these eyes showed evidence of retinal siderosis. No cataracts developed in five eyes with intralenticular glass, while three with intravitreal iron showed marked retinal toxicity. These results suggest that as long as the lenses remain clear, conservative management of these injuries carries minimal risk of permanent retinal damage.

A numeric index based on spatial frequency for the tortuosity of retinal vessels and its application to plus disease in retinopathy of prematurity

BACKGROUND

In retinopathy of prematurity (ROP), tortuosity of vessels near the posterior pole of the fundus is an important clinical sign, yet clinicians have difficulty estimating how tortuous the vessels are.

METHODS

The authors have devised an objective, numeric index of retinal blood vessel tortuosity that is especially sensitive to the structural changes in vessels that occur in ROP, but it is not particularly sensitive to non-ROP changes. Computer software is used to calculate the index from fundus images; the quality of these images is typical of photographs or video-cassette frames that the authors record in the premature nursery.

RESULTS

The index reliably segregates tortuous vessels from nontortuous ones and separates eyes that reach ROP treatment threshold from eyes that do not.

CONCLUSIONS

The index forms an objective measure of the ROP disease state. Its calculation requires only segments of vessels and thus, is potentially adaptable to imaging systems that automatically extract vessel portions from fundus images.

Ocular and associated neuropathologic observations in suspected whiplash shaken infant syndrome. A retrospective study of 12 cases

We examined the eyes of 12 infants who died with the clinical and pathologic diagnosis of the shaken baby syndrome. The ocular histopathologic findings and the neuropathologic findings were compared. Preretinal, intraretinal, and subretinal hemorrhages were observed; hemorrhages of the superficial retinal layers and subsensory retinal space predominated. Retinal hemorrhages were found in 12 cases, intracranial hemorrhage was found in 11 cases, and cerebral edema was found in 10 cases. The intraretinal and periretinal hemorrhages were most prevalent at the posterior pole. Five cases had retinal folds. There was a low incidence of optic disc edema and choroidal hemorrhage.

Clinical predictors of scleral rupture after blunt ocular trauma

We conducted a two-part study to define better the clinical predictors of scleral rupture after blunt trauma. In part 1 we ascertained the prevalence of scleral rupture among a population of patients examined in an ophthalmic emergency room with severe blunt ocular trauma over a six-month period. Scleral rupture was diagnosed in ten of 283 patients (3.5%). In part 2 we compared the clinical findings in 29 patients with scleral rupture to those of 273 patients with no scleral rupture after blunt trauma. We noted that eyes with visual acuity of light perception or less, an intraocular pressure of 5 mm Hg or less, an abnormally deep or shallow anterior chamber, or a media opacity preventing a view of fundus details by indirect ophthalmoscopy, should be considered ruptured when severe intra- or periocular hemorrhage is present. This diagnostic algorithm had a sensitivity of 100.0% (98.7% to 100.0%), specificity of 98.5% (97.1% to 99.9%), and a positive predictive value of 71.4% (66.3% to 76.5%).

Isolated ocular cryptococcosis in an immunocompetent patient

A 62-year-old woman without evidence of immunocompromise was evaluated for uveitis and a subretinal lesion in the right eye. Laboratory evaluation, including cerebrospinal fluid analysis, revealed no apparent cause. The diagnosis of subretinal cryptococcosis was established by transscleral needle biopsy of the subretinal mass. Treatment with intravenous amphotericin B and oral 5-flucytosine brought recovery of visual acuity to 20/30-1 and resolution of the inflammation. This patient demonstrates that ocular cryptococcal infection must be suspected, even in the absence of predisposing factors or systemic findings, and that subretinal fine-needle aspiration is an important diagnostic tool in this setting.

Management of suspected ocular laceration or rupture

The records of 95 consecutive patients with suspected ocular laceration or rupture managed by a single surgeon were reviewed. A total of 86 patients were found to have a laceration or rupture, of whom 79 were followed up, for an average of 6.4 months. In 32 eyes (40%) the final visual acuity was 20/40 or better, and in another 32 the final acuity was less than 5/200. Eyes with lacerations had a better visual outcome than those with rupture due to blunt trauma. Of the 26 eyes operated on for suspected blunt rupture 6 (23%) were found not to have a rupture. Ruptured eyes were more likely than nonruptured eyes to have abnormal anterior chamber depth, vision less than hand motion and hyphema.

Intraocular pressure increase associated with epsilon-aminocaproic acid therapy for traumatic hyphema

We treated five patients receiving epsilon-aminocaproic acid who demonstrated sudden and accelerated clot dissolution with accompanying increases in intraocular pressure 24 to 96 hours after discontinuing treatment. All of these patients required additional ocular hypotensive medications and one patient required anterior chamber washout for persistently increased intraocular pressure. These findings suggest that certain patients with hyphema may be at risk for significant intraocular pressure increases following cessation of epsilon-aminocaproic acid therapy.

The relationship between retinal vessel tortuosity, diameter, and transmural pressure

Increases in retinal vein tortuosity are thought to be caused by increases in vascular transmural pressure. We have attempted to determine the relationship between retinal vessel tortuosity, diameter, and transmural pressure by examining the effects of changes in transmural pressure on latex tubes with fixed ends. As the transmural pressure is raised, tube diameter increases, but tortuosity does not begin increasing until a critical pressure is reached. Above the critical pressure, tortuosity increases more rapidly than diameter. Our results support the above hypothesis and also suggest that at high transmural pressures, retinal vessel tortuosity is a more sensitive indicator than is the diameter of changes in retinal venous transmural pressure, but diameter is more sensitive than tortuosity at lower pressures.

Retinopathy of prematurity: a new look at an old disease

The neovascular changes of the retinopathy of prematurity can occur in premature infants in three settings: (1) when high levels of supplemental oxygen are administered, neovascularization usually commences shortly after cessation of oxygen therapy; (2) when supplemental oxygen is given for long periods of time, neovascularization can develop while the infant is still receiving oxygen; and (3) neovascularization can occur without exposure to any supplemental oxygen. We propose a model which can explain the occurrence of the retinopathy of prematurity in all these settings. Our model demonstrates that whenever the retinopathy of prematurity occurs, arterial oxygen levels are inappropriately high in relation to the stage of retinal vessel development, even in premature neonates not given supplemental oxygen. The inhibitory effect of these elevated oxygen tensions upon carbon dioxide removal is indicated as a possible cause of neovascularization by leading to tissue acidosis and vasodilatation.

Steady-state gas exchange in normothermic, anesthetized, liquid-ventilated dogs

Anesthetized, paralyzed, purebred beagle dogs were ventilated for 45 min (n = 5) and 60 min (n = 5) with oxygenated (PIO2 = 685 mmHg) FC-80 fluorocarbon liquid at 38 degrees C. The PaCO2 remained constant at approximately 43 mmHg during 60 min of liquid ventilation (mean tidal volume = 290 ml, mean respiratory frequency = 2.8 breaths/min). The end-tidal PCO2 was consistently higher than PaCO2 during liquid ventilation. Histological examination by light as well as scanning electron microscopy of the lungs of dogs killed 10, 30, or 180 days after liquid ventilation revealed no pathological changes except for a slight increase in the number of macrophages, especially around the alveolar ducts. It is concluded that a steady state of gas exchange at near normal arterial carbon dioxide partial pressures can be maintained in anesthetized, normothermic dogs ventilated with FC-80 at respiratory frequencies of approximately 3 breaths/min.

Investigations of black bronchoalveolar human lavage fluid

The removal by bronchoalveolar lavage (two occasions) of 10(11) black macrophages containing crystals of aluminum silicate, large amounts of amorphous carbon, and oxidized lipids was followed by considerable improvement in gas exchange in a patient. Sixty-eight percent of these pulmonary macrophages were viable and normal, as judged by chemotatctic and phagocytic activity. Except for cigarettes, no source for the previously mentioned ingested foreign substances was found. These observations suggest that removal by lavage of nonviable macrophages laden with foreign bodies from distal portions of the lungs of pulmonary patients may be therapeutically useful.

A fluorocarbon emulsion with a high solubility for CO2

A stable emulsion can be prepared by subjecting a mixture of 30% (by volume) FC-80 fluorocarbon; a 0.3-M THAM solution titrated to pH 7.4 with HCl; and 0.04 g F68 Pluronic surfactant per milliliter FC-80 to ultrasonic energy. The emulsion has a density of 1.24 g/ml; and absolute viscosity of 2.4 centipoise; and an approximate fluorocarbon-droplet diameter of 3mu. The approximate CO2 content of the emulsion at partial pressures ranging from 30 to 60 mm Hg is 132 ml (STPD)/liter + (5.5 X PCO2). The O2 content in ml (STPD)/liter equals 0.213 X PO2 (mm Hg).

Volume-controlled lung lavage in a woman with cystic fibrosis

A 22-year-old woman with cystic fibrosis was treated by volume-controlled lavage of each of her lungs on two occasions. Following the first lavages, the patient's vital capacity increased by 1.03 liters and her 1-sec forced expiratory volume increased by 0.70 liters/second. Similar improvements, although less pronounced, were noted after both lungs has been lavaged a second time. It is concluded that volume-controlled lung lavage can be of benefit as an adjunct in the treatment of patients with cystic fibrosis.