Side effects and complications of variable-pulsed erbium:yttrium-aluminum-garnet laser skin resurfacing: extended experience with 50 patients

Recent advances in technology have provided laser surgeons with new options for cutaneous laser resurfacing. Despite its popularity, there is limited information on the short-term and long-term side effects and complications of variable-pulsed erbium:yttrium-aluminum-garnet (erbium:YAG) laser skin resurfacing. The purpose of this study was to prospectively evaluate postoperative wound healing, side effects, and complications of multiple-pass, variable-pulsed erbium:YAG laser skin resurfacing for facial photodamage, rhytides, and atrophic scarring. Fifty consecutive patients with facial photodamage, rhytides, or atrophic scarring were treated with a variable-pulsed erbium:YAG laser. Side effects and complications relating to postoperative healing, erythema, and pigmentary changes were tabulated. Patients were evaluated at postoperative days 3 through 7 and at 1, 3, 6, and 12 months after laser skin resurfacing. The average time for reepithelialization was 5.1 days. Prolonged erythema (>1 month) was observed in three patients (6 percent). Transient hyperpigmentation occurred in 20 patients (40 percent), with an average duration of 10.4 weeks. No cases of hypopigmentation or scarring were seen. In summary, a variable-pulsed erbium:YAG laser can safely be used for the treatment of facial photodamage, rhytides, and atrophic scarring. Although more postoperative erythema is seen after variable-pulsed erbium:YAG laser treatment than is usually produced with a short-pulsed erbium:YAG system, the side-effect profile and recovery period after variable-pulsed erbium:YAG laser skin resurfacing still are more favorable than after multiple-pass carbon dioxide laser skin resurfacing.     

Nondébridement of laser char after two carbon dioxide laser passes results in faster reepithelialization

Skin repair following laser injury can be accelerated by using techniques that promote rapid reepithelialization. In this article, the benefit of intraoperative nondébridement of laser debris after two laser passes is discussed. After carbon dioxide laser resurfacing of the face, skin specimens were examined using indirect immunofluorescence with antibodies to specific epidermal and basement membrane proteins. Biopsy specimens obtained immediately after resurfacing showed a greater injury to epidermal and basement membrane proteins when skin was wiped with saline-soaked gauze after laser passes than when there was no débridement after two passes. Later examination of skin specimens obtained from nine patients 2 days after carbon dioxide resurfacing showed that nondébrided, occluded skin had faster reepithelialization than the other treatments. Nondébridement of the skin at the time of resurfacing along with the use of postoperative occlusive dressings led to the rapid reestablishment of a multilayered epidermis only 2 days after resurfacing. Nondébridement along with occlusive dressings results in rapid reepithelialization of the skin after two carbon dioxide laser passes for skin rejuvenation.     

Combined erbium:YAG laser resurfacing and face lifting

Facial aging occurs secondary to gravity-induced tissue ptosis and photoaging. Combined face lifting and carbon dioxide laser resurfacing provides a comprehensive one-stage approach to facial rejuvenation but is condemned by many plastic surgeons due to the nonspecific thermal effects of the laser and risk of skin necrosis. Newer high-energy erbium:YAG lasers allow precise tissue ablation with minimal thermal effect. In this study, various facial rejuvenation techniques were combined with simultaneous erbium:YAG laser resurfacing to assess results and complications. A total of 257 patients from Florida, Melbourne, Australia, and Tel Aviv, Israel, underwent combined erbium:YAG laser resurfacing and surgical facial rejuvenation. Various face-lift methods were used, including endoscopic, deep plane, and subcutaneous. Simultaneous, full-facial laser resurfacing was performed using a variety of erbium:YAG lasers. It was found that combined laser resurfacing and face lifting was successful in greater than 95 percent of patients with minimal morbidity. Two patients (1 percent) (both heavy smokers) developed small areas of skin necrosis that healed with minor pigment changes. Five patients (2 percent) developed synechia that was treated with no residual effect. Two additional patients (1 percent) developed temporary ectropion. There were no other cases of scarring, infection, or cosmetically obvious hypopigmentation. Although larger studies are necessary, it seems that the lack of thermal injury from the erbium:YAG laser makes it possible to safely perform laser resurfacing with surgical facial rejuvenation in nonsmokers. However, the authors caution that familiarity with the nuances of erbium:YAG laser resurfacing be obtained before performing combined laser resurfacing and face lifting.     

Laser blepharoplasty with transconjunctival orbicularis muscle/septum tightening and periocular skin resurfacing: a safe and advantageous technique

Carbon dioxide (CO2) laser blepharoplasty with orbicularis oculi muscle tightening and periorbital skin resurfacing is a safe procedure that produces excellent aesthetic results and diminishes the occurrence of complications associated with skin and muscle resection in the lower lid, particularly permanent scleral show and ectropion. The authors present a review of 196 cases of carbon dioxide laser blepharoplasty and periocular laser skin resurfacing performed at their center from April of 1994 to September of 1998. Of these cases, 113 patients underwent four-lid blepharoplasty, 59 underwent upper lid blepharoplasty only, and 24 underwent lower lid blepharoplasty only. Prophylactic lateral canthopexy was performed in 24 patients. Concomitant procedures (brow lift/rhytidectomy/rhinoplasty) were performed in 92 patients. The carbon dioxide laser blepharoplasty procedure resulted in no injuries to the globe, cornea, or eyelashes. Combined with laser tightening of the orbicularis oculi muscle and septum and periocular skin resurfacing, the transconjunctival approach to lower blepharoplasty preserves lower lid skin and muscle. Elimination of the traditional scalpel skin/muscle flap procedure results in a dramatically lower complication rate, particularly with regard to permanent ectropion and scleral show. Laser shrinkage of the orbicularis muscle and septum through the transconjunctival incision enables the correction of muscle aging changes such as orbicularis hypertrophy and malar festoons. The addition of periocular resurfacing enables the correction of skin aging changes of the eyelid that are not addressed by traditional scalpel blepharoplasty. In addition, lateral canthopexy constitutes an important adjunct to the laser blepharoplasty procedure for the correction of lower lid canthal laxity.     

二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣的疗效分析

目的:探讨二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣的疗效。方法:选择2012年2月~2015年9月在我院进行诊治的扁平疣患者121例,男62例,女59例,其中观察组61例给予二氧化碳激光联合5-氟尿嘧啶注射液治疗,对照组60例给予二氧化碳激光治疗,比较两组的疗效,T淋巴细胞亚群,复发率及不良反应。结果:观察组总有效率为98.36%,明显高于对照组91.67%(P0.05);经治疗后,两组治疗后的CD4+、CD8+和CD4+/CD8+均较治疗前有显著性差异(P0.05);与对照组相比,观察组治疗后的CD4+和CD4+/CD8+明显升高,CD8+明显降低,差异均有统计学意义(P0.05);观察组的复发率为5.88%,明显低于对照组的15.00%(P0.05);两组的不良反应发生情况无明显差异(P0.05)。结论:二氧化碳激光治疗联合5-氟尿嘧啶对扁平疣疗效显著,可明显提高患者免疫功能,降低扁平疣的复发率,值得临床应用推广。     

A new dressing for laser-treated areas

Contemporary studies and observations have left no doubt that occlusive dressings are superior to open treatment after laser resurfacing. The currently available occlusive dressings, however, are time-consuming to apply, often dislodge shortly after application, and most require reapplication. The authors report a cross-sectional observational study of patients who were treated with a new dual silicone-based dressing (DiamondSeal) after full-face laser resurfacing, with or without rhytidectomy. Patients who previously underwent similar surgeries and who were treated with a popular occlusive tape dressing (Flexzan) acted as historic controls. A combination of two silicones produced a gel-like silicone admixture that was spread evenly over the laser-treated areas. The silicone gel solidified into a flexible membrane and remained on the patient's face for 5 days. Questionnaires were sent to patients who were treated with the silicone dressing and those who were treated with a currently popular occlusive dressing. When the attributes of these dressings were compared, the superiority of the silicone dressing approached statistical significance ( = 0.08). The majority of patients treated with the silicone dressing (71 percent) had a positive experience with this dressing, stating they would repeat the experience if necessary. Only 54 percent of patients with a tape dressing were willing to repeat their experience ( = 0.18). The major advantages of this dressing, noted from the surgeon's perspective, were the speed with which the mask was applied; the ease of application, without the need for templates; the acceptable cure duration, allowing spontaneous contouring of the silicone along facial contours; the simple tailoring of the dressing; the reduced need for and minimal time for reapplication; and the paucity of complications.     

Famciclovir as antiviral prophylaxis in laser resurfacing procedures

Latent herpes simplex virus (HSV types I and II) may be reactivated by laser resurfacing procedures, presenting serious postoperative complications in approximately 9 percent of patients. Perioperative prophylactic administration of nucleoside analog antiviral agents has been shown to decrease the duration and severity of postsurgical herpes infection and to prevent recurrence. This study was conducted to assess the efficacy of famciclovir in preventing orofacial herpes virus reactivation and primary infection in patients undergoing laser resurfacing. HSV history was obtained from a total of 121 patients undergoing the procedure. Antiviral prophylaxis with famciclovir was begun 1 to 2 days before surgery and continued for 5 days after surgery. Patients with no history of orofacial herpes (n = 94) received 125 mg of famciclovir twice daily. Those with a history of orofacial herpes (n = 27) received 250 mg of famciclovir twice daily. Postsurgical HSV infection rates in patients receiving famciclovir prophylaxis were compared with those from a similar historical control group of HSV-positive patients (n = 127) who received no prophylaxis. In patients receiving famciclovir prophylaxis, one patient (1.1 percent) in the HSV-negative history group and no patients in the HSV-positive history group had postsurgical herpes infection. Famciclovir significantly reduced postsurgical herpes infection when compared with the 9.4 percent rate of herpes reactivation in patients who received no prophylaxis (p = 0.003). This study suggests that twice-daily famciclovir prophylaxis markedly reduces orofacial herpes virus infection in patients undergoing laser resurfacing.     

The effect of carbon dioxide laser surgery on the recurrence of keloids

The efficacy of carbon dioxide laser excision as a primary modality for the treatment of keloids was evaluated. This retrospective study focuses on 31 patients with one or more keloids, 23 of whom were available for follow-up after carbon dioxide laser excision. The patients' ages ranged from 5 to 72 years. There were 16 females and 7 males. One patient was Caucasian, 22 patients were non-Caucasian, and there were no Asians. The keloids that were excised ranged in size from 1 to 30 cm in greatest diameter. One patient had no recurrence of her keloid after carbon dioxide laser excision, 9 patients required steroids to suppress recurrences, and 13 patients were considered failures. Reasons for the failure of this modality, as well as speculation regarding the future of this procedure, are discussed.     

Carbon dioxide laser resurfacing and thin skin grafting in the treatment of "stable and recalcitrant" vitiligo

Various surgical methods have been used in the treatment of small stable vitiliginous areas, but there is no established surgical approach for larger vitiligo areas and therapy-resistant anatomic sites, such as the hands. Two years ago, we successfully treated large burn scar depigmentation areas at different anatomic sites using carbon dioxide laser resurfacing and thin (0.2 to 0.3 mm) skin grafting. The purpose of this study was to investigate the effectiveness of our method in treating large, stable, and recalcitrant vitiligo areas. Thirteen anatomic sites of seven male patients, whose ages ranged from 20 to 22 years, were treated. The locations of the treated areas were as follows: seven areas on the dorsum of the hands, two areas on the forearms, two areas in the pretibial region, one area on the lateral thigh, and one area in the presternal region. The surface area of treated vitiligo sites ranged from 0.5 to 6 percent of total body surface area (mean, 2.5 percent). Skin graft take was excellent in all patients except for one. The follow-up period for these patients ranged from 6 to 18 months, with an average follow-up period of 14 months. Early and complete repigmentation was achieved and the color match was good or excellent in all patients. No depigmentation occurred again in the treated areas or graft donor sites. In conclusion, with careful patient selection and delicate surgical technique, our method was effective in treating large areas of vitiligo over the extremities and dorsum of hands, which were refractory to other therapies and could not be hidden.     

Development of a novel nonantigenic dermal implant composed of human placental collagen

Injectable bovine collagen has proven to be safe and effective for the treatment of contour defects for more than 20 years. After intradermal exposure to bovine collagen, the most commonly reported side effect is hypersensitivity (incidence of approximately 3 percent to test and approximately 1 to 2 percent to subsequent treatment). The main purpose of this study was to evaluate tissue response and antibody production in bovine collagen-sensitive patients who were treated with human collagen (predominantly type I) implant. Twenty-seven patients with confirmed hypersensitivity to bovine collagen received a depot of human collagen implant and then were treated for facial contour defects on two to five separate occasions over a 9- to 12-month period and followed through 36 months. Measurement of antibody titers indicated that none of the subjects receiving human collagen implant developed antibodies against human collagen, even in the presence of positive antibody titers against bovine collagen. Histologic examination of the depot sites in these patients showed only mild inflammation. These findings indicate that treatment with human collagen did not elicit an allergic response in these subjects who had confirmed hypersensitivity to bovine collagen.     

Allergic Skin Test Reactivity to Marijuana in the Southwest

In a general allergy consultation practice in Arizona and western New Mexico, 129 patients were tested for immediate hypersensitivity skin test reactivity to marijuana pollen and tobacco leaf, as well as to a battery of other antigens. In all, 90 patients were diagnosed as allergic (atopic) and, of these, 63 (70 percent) were found to be skin test reactive to marijuana pollen and 18 (20 percent) to tobacco leaf. The incidence of skin test reactivity to marijuana was not significantly different for persons living at low, middle or high elevations throughout the Southwest. Marijuana sensitivity occurred in patients who were, in general, also sensitive to a variety of other airborne plant pollens. There was no close correlation, however, between sensitivity to marijuana pollen and sensitivity to pollens from elm, mulberry, hop and stinging nettle, which are botanically related to marijuana. The data suggest that marijuana pollen may be a relatively common airborne pollen pollutant in the Southwest, allergic persons being sensitized through inhalation. If this is confirmed by further studies, then clinical investigation of marijuana hyposensitization (immunotherapy) may be warranted. This is in contrast to tobacco allergy for which simple avoidance is recommended.     

Ventilatory sensitivity to carbon dioxide before and after episodic hypoxia in women treated with testosterone.

We hypothesized that the ventilatory threshold and sensitivity to carbon dioxide in the presence of hypoxia and hyperoxia during wakefulness would be increased following testosterone administration in premenopausal women. Additionally, we hypothesized that the sensitivity to carbon dioxide increases following episodic hypoxia and that this increase is enhanced after testosterone administration. Eleven women completed four modified carbon dioxide rebreathing trials before and after episodic hypoxia. Two rebreathing trials before and after episodic hypoxia were completed with oxygen levels sustained at 150 Torr, the remaining trials were repeated while oxygen was maintained at 50 Torr. The protocol was completed following 8-10 days of treatment with testosterone or placebo skin patches. Resting minute ventilation was greater following treatment with testosterone compared with placebo (testosterone 11.38 +/- 0.43 vs. placebo 10.07 +/- 0.36 l/min; P < 0.01). This increase was accompanied by an increase in the ventilatory sensitivity to carbon dioxide in the presence of sustained hyperoxia (VSco(2)(hyperoxia)) compared with placebo (3.6 +/- 0.5 vs. 2.9 +/- 0.3; P < 0.03). No change in the ventilatory sensitivity to carbon dioxide in the presence of sustained hypoxia (VSco(2 hypoxia)) following treatment with testosterone was observed. However, the VSco(2 hypoxia) was increased after episodic hypoxia. This increase was similar following treatment with placebo or testosterone patches. We conclude that treatment with testosterone leads to increases in the VSco(2)(hyperoxia), indicative of increased central chemoreflex responsiveness. We also conclude that exposure to episodic hypoxia enhances the VSco(2 hypoxia), but that this enhancement is unaffected by treatment with testosterone.     

Reaction to injectable collagen: results in animal models and clinical use

Since its commercial release, Zyderm collagen implant has been used to treat more than 200,000 subjects in the United States for soft-tissue contour defects and more than 250,000 patients internationally (including the United States). Approximately 3 percent of subjects' skin tested with Zyderm collagen experience localized hypersensitivity reactions to collagen, whereas approximately 1 percent of treated patients demonstrate symptoms of hypersensitivity at treatment sites. Of the latter treatment responses reported since the conclusion of clinical trials with Zyderm, 56 percent occurred following the first treatment, 28 percent following the second, 10 percent following the third, and 6 percent following subsequent exposures. The data indicate that most patients receive a median of three treatments (mean = 4.4) with Zyderm collagen, but most patients who are likely to develop sensitivity to Zyderm collagen appear to respond immunologically to the test implant or first treatment exposure. Examining these treatment responses, 45 percent of the patients reported an onset of symptoms within 10 days and 22 percent at more than 30 days following the last treatment with Zyderm collagen. Erythema was the sole symptom in 24 percent of cases, whereas erythema plus induration comprised an additional 42 percent. Antibodies against Zyderm collagen were detected in the sera of 88 percent of these subjects using an ELISA, but no reactivity was observed against human collagen. Sera from patients reporting only systemic symptoms were not found to have anticollagen antibodies. These data suggest that the relative risk of a hypersensitivity reaction to Zyderm collagen does not increase with multiple exposures, since patients who are going to develop an immune response to bovine collagen react with greatest frequency to initial injections of collagen. In animal models, Zyderm collagen was shown to be less immunogenic than other medical devices which are composed of bovine collagen. Specifically, comparative studies were conducted in which Zyderm collagen and hemostatic agents were implanted in the guinea pig subcutaneum: sera from animals treated with collagen-derived hemostatic devices possessed significant levels of anti-implant antibodies (titers greater than 640), whereas animals treated with Zyderm collagen mounted minimal responses (titers less than 40). Additional studies were conducted in which implant materials were compared in a guinea pig parietal (bony defect) model and in a rabbit hemostasis model: in both, Zyderm collagen demonstrated lower immunogenicity than commercial bovine collagen hemostatic agents. Histologic results from these studies showed Zyderm     

A controlled evaluation of dermabrasion versus CO2 laser resurfacing for the treatment of perioral wrinkles

Facial skin treatments with laser resurfacing, dermabrasion, and chemical peels were responsible for a significant portion of the 2.7 million cosmetic procedures performed in 1998. Perioral wrinkles are a common problem for which plastic surgical consultation is obtained. The aim of this study was to compare and quantify the advantages and disadvantages of laser resurfacing versus dermabrasion in the treatment of perioral wrinkles. Twenty female patients provided informed consent and participated in the study. Half of the perioral area was treated with dermabrasion and half was treated with the UltraPulse CO2 laser. The two procedures were compared using high-quality photographs; a biophysical evaluation of skin color, hydration, and mechanical properties; and patient evaluation of outcomes. Photographs were evaluated by 10 board-certified plastic surgeons who were blinded to the treatment methods. The laser treatment had a significantly higher erythema score at 1 month and a small but significantly greater improvement in perioral wrinkles at 6 months. Thirteen subjects selected the laser treatment as producing the best result, despite the greater intraoperative pain for this procedure. Biomechanical measurements suggest that the laser treatment produced a skin state more similar to skin in younger patients, presumably with higher levels and/or greater organization of the collagen and elastin. Patient preference was inferred from the resurfacing method that they would recommend to a friend. Although the laser was selected as the best result in a majority of cases, patient preference was equally distributed between the two treatments. The authors think that by studying and quantifying the biophysical changes that occur as a result of CO2 laser resurfacing, greater improvements in restoring actinic damage (e.g., wrinkles) can be achieved. Patients consider more than the objective skin changes from a resurfacing technique when making a recommendation to a friend.     

Retinoic acid and CO2 laser resurfacing

The purpose of this study was to analyze the effect of retinoic acid on wound healing and depth of injury in an animal skin model resurfaced with a CO2 laser. The dorsal skin of 21 Hartley guinea pigs was divided into halves. One-half received a daily application of 0.05% retinoic acid for 28 days, whereas the other half served as the control. The animals were divided into three treatment groups of seven animals. Group A was laser resurfaced with one pass of the Coherent UltraPulse CO2 laser (300 mJ, 60 W, density 40 percent). Group B received two passes, and group C received three passes. Histologic studies were obtained before laser resurfacing and days 1, 4, and 7 after resurfacing. Depth of injury, thickness, number of squamous cell and granular cell layers, and epithelialization rates were measured. We found that the depth of injury was statistically less in animals pretreated with retinoic acid. Granular cells were thicker and more numerous at day 4 in pretreated animals but similar to controls by day 7. Animals pre-treated with retinoic acid overall seemed to heal wounds earlier. In conclusion, pretreatment with retinoic acid may reduce the depth of injury in laser resurfacing and speed healing rates.     

Long-term histologic effects of the CO2 laser

The long-term histologic effects of CO2 laser resurfacing previously were unknown. Prior investigations have clearly defined the photothermal effect. Collagen shrinkage as a reaction to increased tissue temperature between 60 and 70 degrees C has also been previously described. Twenty-two patients completed a 1-year study in which biopsy specimens from the upper lip were taken preoperatively and 6 weeks, 6 months, and 1 year after CO2 laser resurfacing. Trichrome stains and Verhoeff-van Gieson stains were used to demonstrate tissue collagen and tissue elastin. Neocollagenesis beginning at 6 weeks and progressively increasing at 6 months and 1 year was clearly demonstrated. Neoelastogenesis showed significant increases at 6 months and 1 year. It is hypothesized that the additive effects of initial collagen shrinkage and the long-term effect of neocollagenesis and neoelastogenesis are the significant factors contributing to the long-lasting and excellent results of CO2 laser skin resurfacing.     

Sensitivity to mugwort pollen allergens (Artemisia vulgaris)

The author has found that 42% of patients with pollinosis had positive skin reactions with mugwort (Artemisia vulgaris) pollen allergens. The majority of tested patients (139 out of 187) were also allergic to grass pollens. However, hypersensitivity to mugwort pollen allergens was isolated and did not accompany grass pollen allergy. The symptoms of pollinosis appeared in this group later than in patients sensitive to grass pollen allergens only (over 21 years of age in 71%). Bronchial asthma was diagnosed in 40% of these patients and allergic skin reactions in 25%. Sensitivity to mugwort pollen allergens was accompanied by the sensitivity to pollen allergens of Graminae family of plants in 80% of cases. The author suggests that sensitivity to mugwort pollen allergens is the second most frequent cause of the pollinosis and is diagnosed too rarely. Failures of desensitization in patients sensitive to pollen allergens of Graminae family of plants may often result from coexisting sensitivity to mugwort pollen allergens as this sensitivity produces not only season but perennial clinical symptoms in nearly 50% of patients. The author discusses also botanical relations and cross-reactions in allergy to mugwort and ragweed pollen allergens.     

Lower eyelid blepharoplasty: analysis of indications and the treatment of 100 patients

Traditionally, lower lid blepharoplasty has been confined to a choice of skin or skin-muscle flap transcutaneous blepharoplasty. In the past decade, in particular, various new techniques and technologies have emerged, altering our ability to treat the lower eyelids. These techniques include transconjunctival blepharoplasty, a variety of canthopexy procedures, fat-conserving or fat-replacing methods, wedge excision, and laser resurfacing techniques, and they allow a more individualized approach based on variations in anatomical features and patient goals. A retrospective review of data for 100 consecutive patients (ranging in age from 30 to 80 years) who underwent lower eyelid procedures during a 12-month period is presented. Procedures were categorized as follows: lower lid blepharoplasty, 35 cases; lower lid transconjunctival blepharoplasty, 27 cases; lower lid transconjunctival blepharoplasty with laser resurfacing, 17 cases; lower lid laser resurfacing, 16 cases; tarsorrhaphy with lower lid operation, three cases; tarsorrhaphy with laser resurfacing, two cases. Two complications of retained fat pads (one medial and one lateral) were encountered and were addressed with a secondary operation using a transconjunctival blepharoplasty approach. The results indicate that laser treatment has become the predominant form of lower eyelid resurfacing and that transconjunctival blepharoplasty is now the most common surgical procedure for the lower eyelid. All of our tarsorrhaphy procedures were performed for patients who had previously undergone surgical treatment of the lower eyelids. An algorithm based on physical findings and these techniques has been developed, for appropriate tailoring of the procedure to each patient's specific concerns. With the availability of a variety of techniques, an individualized approach based on variations in anatomical features is feasible.     

Epidemiologic studies on allergic diseases among rural and urban school children in Poland

451 rural children (group I) and 2000 urban children (group II) aged 10-16 years from Toruń province were inquired by a questionnaire to their parents or guardians. 9.09% of children in the country and 13.45% of those living in the city of Toruń suffered from hypersensitivity disorders; bronchial asthma was reported in 2.22% and 3.05% of cases, allergic rhinitis--in 3.77% and 7.15%, allergic conjunctivitis--in 1.33% and 2.75%, allergic edema--in 0.44% and 0.60%, urticaria--in 1.55% and 3.50%, and infantile eczema--in 0.44% and 2.10% of cases, respectively. The pollinosis prevalence rate was 2.00% in group I and 1.85% in group II. At least 2 various forms of hypersensitivity coexisted in 30.48% of allergic urban children (64.86% of patients with pollinosis among them); infantile eczema preceded allergic rhinitis and bronchial asthma symptoms in 6.29% and 11.47% of cases, respectively, while allergic rhinitis occurred before the onset of bronchial asthma in 24.59% of asthmatic children. 37.10% of individuals with positive family history of allergic conditions also fell ill with some diseases of this nature, while in those with negative family history allergy occurred only in 10.22% of cases. From environmental factors mother's diseases during pregnancy, bottle feeding and a regular diet during the first year of life, frequent respiratory infections in the early childhood and poor living conditions increased the risk of allergic diseases or aggravated their course in the population examined.     

Chemoreceptor sensitivity and maladaptation to high altitude in man

Studies were carried out to find out the role of chemoreceptor sensitivity in the causation of maladaptation syndromes on acute exposure to altitude. The experiments were done in two phases. In phase I, the responses in chemoreceptor sensitivity were studied in altitude acclimatized subjects and compared with those who suffered from either High Altitude Pulmonary Oedema (HAPO) or Acute Mountain Sickness (AMS). In Phase II, a similar comparison was done in two groups of subjects, one representing normal sojourners at 3,500 m and the other being subjects who had just recovered from HAPO. The first phase was done at Delhi; and the second at an altitude of 3,500 m. Parameters of assessment were hypoxic sensitivity, carbon dioxide sensitivity, ventilation (VE), respiratory frequency (Rf), forced vital capacity (FVC), forced expiratory volume at the first second (FEV1), heart rate (HR), blood pressure (BP), and oral temperature (Tor). The results showed significantly lower sensitivity to both hypoxia and carbon dioxide in maladapted subjects, as compared to those who were acclimatized in both the categories suggesting thereby that reduced chemoreceptor sensitivity might be an initiating factor in the causation of maladaptation syndromes at altitude.