Ron B. Somogyi

Changes in respiratory control after 5 days at altitude.

These experiments examined changes in the chemoreflex control of breathing and acid-base balance after 5 days at altitude (3480 m) in six healthy males. The partial pressures of carbon dioxide (P(CO2)) at which ventilation increased during isoxic hypoxic and hyperoxic modified rebreathing tests at sea level fell significantly at altitude by mean+/-S.E.M. of 12.8+/-2.51 mmHg and 9.5+/-1.77 mmHg, respectively, but response slopes above threshold were unchanged. Altitude exposure produced a respiratory alkalosis evidenced by a decrease in mean resting end-tidal P(CO2) from 41+/-0.84 mmHg at sea level to 32+/-2.04 mmHg at altitude, but pH did not increase significantly from its sea level value. Blood samples were analyzed to discover acid-base changes, using a modification of the equations for acid-base balance proposed by [Stewart, P.A., 1983. Modern quantitative acid-base chemistry. Can. J. Physiol. Pharmacol. 61, 1444-1461]. While strong ion difference at altitude was not significantly different from its sea level value, albumin concentration was increased significantly from 38.6+/-0.30 g L(-1) to 49.8+/-0.76 g L(-1). We suggest that the respiratory alkalosis was produced by a fall in the chemoreflex threshold and pH was corrected by an elevation in the concentration of weakly dissociated protein anions.

Venous thromboembolism in abdominoplasty: a comprehensive approach to lower procedural risk.

BACKGROUNDnVenous thromboembolism (VTE) is a serious and potentially life-threatening surgical complication. However, there is little consensus regarding appropriate VTE prophylaxis for plastic surgery patients. Risk factors as they apply to plastic surgery patients are unclear, and recent recommendations for chemoprophylaxis in these patients may expose them to other additional risks.nnnOBJECTIVESnThe authors examine perioperative and intraoperative measures, specifically those that have enabled a large number of patients to undergo outpatient abdominoplasty safely, with a reduced risk of VTE.nnnMETHODSnA retrospective review was performed of 404 consecutive abdominoplasty patients who were treated at a single outpatient surgery center between 2000 and 2010. Graded compression stockings and intermittent pneumatic compression devices were placed on all patients, and perioperative and intraoperative warming was strictly applied. Progressive tension suturing technique was performed in all cases and drains were eliminated. All patients received pain pumps, ambulated within one hour of surgery, and were discharged home the same day. Patient VTE risk factors were scored with the Caprini/Davison risk assessment model (RAM). Perioperative and intraoperative measures were taken to reduce factors that may increase VTE risk in abdominoplasty. Complications were recorded, including VTE events, seromas, hematomas, and infections.nnnRESULTSnIn this series, 247 abdominoplasty procedures were performed alone and 157 were combined with additional procedures. Under the RAM, 297 patients were considered high risk and 17 highest risk. Abdominoplasty operative time was 100 ± 29 minutes. Only one case of deep vein thrombosis (DVT) occurred, in the calf.nnnCONCLUSIONSnA comprehensive approach to perioperative and intraoperative patient care has allowed outpatient abdominoplasty to be safely performed without VTE chemoprophylaxis in patients with fewer than six risk factors.

Outcomes in primary breast augmentation: a single surgeon's review of 1539 consecutive cases.

Background: The use of implants in aesthetic breast surgery may lead to complications resulting in the need for reoperation. This study examines outcomes following breast augmentation in a single surgeon’s practice and investigates the effect of implant selection and surgical technique on complications and reoperations. Methods: A retrospective review of a single surgeon’s prospectively maintained database over 15 years was performed. All primary bilateral breast augmentation patients were included. Implant characteristics—including implant type, fill, shape, surface, and projection; incision type; and pocket location—were collected. Complications and reasons for reoperation were analyzed using survival analysis. Results: One thousand five hundred thirty-nine patients with 3078 implants were included. Implant types included 596 shaped textured gel, 515 round smooth saline, 192 round textured gel, and 236 round smooth gel implants. Follow-up ranged from 0 to 155 months (average, 18 months). Total complication and reoperation rates were 6.8 and 7.7 percent, respectively. Inframammary incisions and the use of shaped textured gel implants were associated with lower rates of complications. The use of a dual-plane II or III pocket, and implant volumes over 400 cc, were associated with higher rates of complications. Full-projection round implants had rates of complications and reoperations equivalent to those of moderate-projection devices. Both textured shaped gel implants and a subpectoral pocket location were associated with the lowest rates of capsular contracture. Conclusion: This large series of breast implant patients demonstrates that both implant- and technique-related factors may influence complications and reoperations in breast implant surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Efficiency of oxygen administration: sequential gas delivery versus "flow into a cone" methods.

Objective:Fio2 values of a new oxygen mask that exploits efficiencies afforded by sequential gas delivery (SGD) were compared to those of a nonrebreathing mask (NRM) and a Venturi oxygen mask. Design:Prospective, single-blinded, randomized study. Setting:Laboratory study. Subjects:Eight healthy male volunteers. Interventions:Volunteers breathed through each of the masks at various minute ventilations (&OV0312;e). Oxygen flows were 2, 4, and 8 L/min to the SGD mask but only 8 L/min to the other masks. Measurements and Main Results:Net Fio2 was calculated from end-tidal fractional concentrations of oxygen and CO2 with the alveolar gas equation. Only the SGD mask at an oxygen flow of 8 L/min consistently provided both Fio2 >0.95 (at resting &OV0312;e) and higher Fio2 than the other masks at all &OV0312;e. The SGD mask delivered Fio2 comparable to other masks at only a fraction of the oxygen flow and was characterized by a consistent relation between Fio2 and oxygen flow for a given &OV0312;e. Conclusion:We conclude that SGD can be exploited to provide Fio2 >0.95 with oxygen flows as low as 8 L/min, as well as accurate and efficient dosing of oxygen even in the presence of hyperpnea.

Current Practices and Barriers to the Integration of Oncoplastic Breast Surgery: A Canadian Perspective

AbstractBackgroundDespite the safety and popularity of oncoplastic surgery, there is limited data examining utilization and barriers associated with its incorporation into practice. This study examines the use of oncoplastic techniques in breast conserving surgery and determines the barriers associated with their implementation.MethodsA 13-item survey was mailed to all registered general surgeons in Ontario, Canada. The survey assessed surgeon demographics, utilization of specific oncoplastic techniques, and perceived barriers.ResultsA total of 234 survey responses were received, representing a response rate of 32.2xa0% (234 of 725). Of the respondents, 166 surgeons (70.9xa0%) reported a practice volume of at least 25xa0% breast surgery. Comparison was made between general surgeons performing oncoplastic breast surgery (Nxa0=xa079) and those who did not use these techniques (Nxa0=xa087). Surgeon gender, years in practice, fellowship training, and access to plastic surgery were similar across groups. Both groups rated the importance of breast cosmesis similarly. General surgeons with a practice volume involving >50xa0% breast surgery were more likely to use oncoplastic techniques (OR 8.82, pxa0<xa0.001) and involve plastic surgeons in breast conserving surgery (OR 2.21, pxa0=xa0.02). For surgeons not performing oncoplastic surgery, a lack of training and access to plastic surgeons were identified as significant barriers. For those using oncoplastic techniques, the absence of specific billing codes was identified as a limiting factor.ConclusionsLack of training, access to plastic surgeons, and absence of appropriate reimbursement for these cases are significant barriers to the adoption of oncoplastic techniques.nDespite the safety and popularity of oncoplastic surgery, there is limited data examining utilization and barriers associated with its incorporation into practice. This study examines the use of oncoplastic techniques in breast conserving surgery and determines the barriers associated with their implementation. A 13-item survey was mailed to all registered general surgeons in Ontario, Canada. The survey assessed surgeon demographics, utilization of specific oncoplastic techniques, and perceived barriers. A total of 234 survey responses were received, representing a response rate of 32.2xa0% (234 of 725). Of the respondents, 166 surgeons (70.9xa0%) reported a practice volume of at least 25xa0% breast surgery. Comparison was made between general surgeons performing oncoplastic breast surgery (Nxa0=xa079) and those who did not use these techniques (Nxa0=xa087). Surgeon gender, years in practice, fellowship training, and access to plastic surgery were similar across groups. Both groups rated the importance of breast cosmesis similarly. General surgeons with a practice volume involving >50xa0% breast surgery were more likely to use oncoplastic techniques (OR 8.82, pxa0<xa0.001) and involve plastic surgeons in breast conserving surgery (OR 2.21, pxa0=xa0.02). For surgeons not performing oncoplastic surgery, a lack of training and access to plastic surgeons were identified as significant barriers. For those using oncoplastic techniques, the absence of specific billing codes was identified as a limiting factor. Lack of training, access to plastic surgeons, and absence of appropriate reimbursement for these cases are significant barriers to the adoption of oncoplastic techniques.

The effects of carbon monoxide on respiratory chemoreflexes in humans.

As protection against low-oxygen and high-carbon-dioxide environments, the respiratory chemoreceptors reflexly increase breathing. Since CO is also frequently present in such environments, it is important to know whether CO affects the respiratory chemoreflexes responsiveness. Although the peripheral chemoreceptors fail to detect hypoxia produced by CO poisoning, whether CO affects the respiratory chemoreflex responsiveness to carbon dioxide is unknown. The responsiveness of 10 healthy male volunteers were assessed before and after inhalation of approximately 1200 ppm CO in air using two iso-oxic rebreathing tests; hypoxic, to emphasize the peripheral chemoreflex, and hyperoxic, to emphasize the central chemoreflex. Although mean (SEM) COHb values of 10.2 (0.2)% were achieved, no statistically significant effects of CO were observed. The average differences between pre- and post-CO values for ventilation response threshold and sensitivity were -0.5 (0.9) mmHg and 0.8 (0.3) L/min/mmHg, respectively, for hyperoxia, and 0.7 (1.1) mmHg and 1.2 (0.8) L/min/mmHg, respectively, for hypoxia. The 95% confidence intervals for the effect of CO were small. We conclude that environments with low levels of CO do not have a clinically significant effect acutely on either the central or the peripheral chemoreflex responsiveness to carbon dioxide.

Conservative mastectomies and immediate reconstruction with the use of ADMs

BACKGROUNDnIn recent years, a novel approach to immediate breast reconstruction has been introduced with the advent of acellular dermal matrix (ADM). In the setting of conservative mastectomies where the native skin envelope is preserved, placement of ADM at the lower pole in continuity with the pectoralis major muscle (PMM) provides additional support, allowing direct-to-implant breast reconstruction. The following manuscript presents the senior authors experience with ADM-assisted reconstruction and provides a detailed description of surgical technique along with a comprehensive discussion of patient selection and potential complications.nnnMETHODSnA retrospective chart review of patients undergoing direct-to-implant breast reconstruction following skin sparing or nipple sparing mastectomy with the use of ADM (AlloDerm; LifeCell Corp., Branchburg, USA) was conducted at Womens College Hospital in Toronto over a 5-year period [2008-2013]. Demographic data, previous radiation therapy and post-operative complications were recorded.nnnRESULTSnA total of 72 patients representing 119 breasts were identified. Average follow-up was 16 months (range, 3-51 months). Twenty-seven complications were recorded for a complication rate of 22.7% (27/119). Complications included six cases of capsular contracture (Baker III/IV), five cases of red skin syndrome, four cases of rippling, three cases of dehiscence and two cases of seroma. Overall, direct-to-implant reconstruction was successfully completed in 97.5% of breasts (116/119). One case of infection was treated with explantation and conversion to autogenous reconstruction. Two breasts with tissue necrosis or dehiscence had the implants removed and replaced with tissue expanders. Overall reoperation rate was 9.7% (7/72 patients).nnnCONCLUSIONSnADM assisted direct-to-implant breast reconstruction has been shown to be a safe option for women who are candidates for skin sparing or nipple sparing mastectomies. Judicious patient selection, effective collaboration between the oncologic and reconstructive surgeon, careful evaluation of post-mastectomy skin flaps and precise surgical technique are paramount to the success of this technique.

Secondary Breast Augmentation

LEARNING OBJECTIVESnAfter studying this article, the participant should be able to: 1. Assess common clinical problems in the secondary breast augmentation patient. 2. Describe a treatment plan to correct the most common complications of breast augmentation. 3. Provide surgical and nonsurgical options for managing complications of breast augmentation. 4. Decrease the incidence of future complications through accurate assessment, preoperative planning, and precise surgical technique.nnnSUMMARYnBreast augmentation has been increasing steadily in popularity over the past three decades. Many of these patients present with secondary problems or complications following their primary breast augmentation. Two of the most common complications are capsular contracture and implant malposition. Familiarity and comfort with the assessment and management of these complications is necessary for all plastic surgeons. An up-to-date understanding of current devices and techniques may decrease the need to manage future complications from the current cohort of breast augmentation patients.

Correction of Small Volume Breast Asymmetry Using Deep Parenchymal Resection and Identical Silicone Implants: An Early Experience

BACKGROUNDnVirtually all patients presenting for augmentation mammaplasty will exhibit some degree of asymmetry. The use of asymmetric implants to address small- volume breast asymmetry introduces uncontrolled variables into the longevity of postoperative results.nnnOBJECTIVESnWe described a novel method of addressing small-volume asymmetry using deep parenchymal resection (DPR) to achieve symmetry prior to insertion of identical implants. We also compared our results with this technique to a cohort of standard augmentation mammaplasty patients.nnnMETHODSnAll patients underwent 3-dimensional (3D) imaging during consultation. In patients with small-volume breast asymmetry, a uniform disk of deep parenchymal tissue was resected from the base of the larger breast cone through an inframammary incision. A standard submuscular augmentation was then completed. Five patients (DPR group) with appreciable small-volume asymmetry underwent DPR in the larger breast prior to insertion of identical implants. Fifty-six consecutive patients with no appreciable volume asymmetry (standard group) underwent standard submuscular breast augmentation.nnnRESULTSnUsing 3D imaging preoperatively, DPR-group patients had an estimated breast volume asymmetry of 86 ± 58 g and had 55 ± 27 g excised from the larger breast intraoperatively, allowing for insertion of identical implants in each patient. Complications in the standard group included 1 case of rippling and 2 cases of malposition. One case of malposition was noted in the DPR group. No other complications were recorded in either group over 6 months.nnnCONCLUSIONSnOur novel method of addressing small-volume breast asymmetry allows for the use of identical implants and presents no increase in early complications.

Efficient Breathing Circuit for Use at Altitude

Abstract We describe a case report of a subject suffering high-altitude cerebral and pulmonary edema successfully treated with low flow rates of supplemental oxygen administered with a breathing system designed to conserve oxygen supplies at high altitude.