Richard E. Moon

Nitric oxide in the human respiratory cycle

Interactions of nitric oxide (NO) with hemoglobin (Hb) could regulate the uptake and delivery of oxygen (O2) by subserving the classical physiological responses of hypoxic vasodilation and hyperoxic vasconstriction in the human respiratory cycle. Here we show that in in vitro and ex vivo systems as well as healthy adults alternately exposed to hypoxia or hyperoxia (to dilate or constrict pulmonary and systemic arteries in vivo), binding of NO to hemes (FeNO) and thiols (SNO) of Hb varies as a function of HbO2 saturation (FeO2). Moreover, we show that red blood cell (RBC)/SNO-mediated vasodilator activity is inversely proportional to FeO2 over a wide range, whereas RBC-induced vasoconstriction correlates directly with FeO2. Thus, native RBCs respond to changes in oxygen tension (pO2) with graded vasodilator and vasoconstrictor activity, which emulates the human physiological response subserving O2 uptake and delivery. The ability to monitor and manipulate blood levels of NO, in conjunction with O2 and carbon dioxide, may therefore prove useful in the diagnosis and treatment of many human conditions and in the development of new therapies. Our results also help elucidate the link between RBC dyscrasias and cardiovascular morbidity.

Reduced Length of Hospital Stay in Colorectal Surgery after Implementation of an Enhanced Recovery Protocol

BACKGROUND:Enhanced recovery after surgery (ERAS) is a multimodal approach to perioperative care that combines a range of interventions to enable early mobilization and feeding after surgery. We investigated the feasibility, clinical effectiveness, and cost savings of an ERAS program at a major U. S. teaching hospital. METHODS:Data were collected from consecutive patients undergoing open or laparoscopic colorectal surgery during 2 time periods, before and after implementation of an ERAS protocol. Data collected included patient demographics, operative, and perioperative surgical and anesthesia data, need for analgesics, complications, inpatient medical costs, and 30-day readmission rates. RESULTS:There were 99 patients in the traditional care group, and 142 in the ERAS group. The median length of stay (LOS) was 5 days in the ERAS group compared with 7 days in the traditional group (P < 0.001). The reduction in LOS was significant for both open procedures (median 6 vs 7 days, P = 0.01), and laparoscopic procedures (4 vs 6 days, P < 0.0001). ERAS patients had fewer urinary tract infections (13% vs 24%, P = 0.03). Readmission rates were lower in ERAS patients (9.8% vs 20.2%, P = 0.02). DISCUSSION:Implementation of an enhanced recovery protocol for colorectal surgery at a tertiary medical center was associated with a significantly reduced LOS and incidence of urinary tract infection. This is consistent with that of other studies in the literature and suggests that enhanced recovery programs could be implemented successfully and should be considered in U.S. hospitals.

Outcome analysis in patients with primary necrotizing fasciitis of the male genitalia

OBJECTIVES To characterize patients with primary necrotizing fasciitis of the male genitalia (Fourniers gangrene) and to identify risk factors and prognostic variables of survival. METHODS Fifty consecutive patients with primary necrotizing fasciitis of the male genitalia treated at our institution during a 15-year period between 1984 and 1998 were retrospectively analyzed. Of these patients, 44 (88.0%) were found to be eligible for analysis of the outcome parameters. Univariate survival analysis was performed using the Kaplan-Meier algorithm followed by multivariate analysis of statistically significant variables. Six patients (12.0%) who were severely immunocompromised were studied separately. RESULTS Medical comorbidities were prevalent, with diabetes being the most common condition (50%). The overall mortality rate was 20% (10 of 50). Three statistically significant predictors of outcome were identified among the variables analyzed. These were the extent of the infection (P = 0.0262), the depth of the necrotizing infection (P = 0.0107), and treatment with hyperbaric oxygen (P = 0.0115). Multivariate regression analysis of these variables identified the extent of the infection (P = 0.0234) as the only statistically significant, independent predictor of outcome in the presence of other covariables. CONCLUSIONS The involved body surface area appears to be the most important prognostic variable, with a significant impact on outcome. Given the high mortality of the disease entity and a trend toward the improved survival of patients receiving hyperbaric oxygen, this treatment form appears indicated in more severe cases. Immunocompromised patients, who frequently have an atypical and fulminant clinical course, appear to constitute a separate group with a dismal prognosis.

What Is the Role of Hyperbaric Oxygen in the Management of Bisphosphonate-Related Osteonecrosis of the Jaw: A Randomized Controlled Trial of Hyperbaric Oxygen as an Adjunct to Surgery and Antibiotics

PURPOSE This study tested hyperbaric oxygen (HBO) as an adjunct to surgery and antibiotics in the treatment of bisphosphonate-related osteonecrosis of the jaw (ONJ) and evaluated its effects on gingival healing, pain, and quality of life. MATERIALS AND METHODS The investigators implemented a randomized controlled trial and enrolled a sample composed of patients with ONJ, where the predictor variable was HBO administered at 2 atm twice a day for 40 treatments as an adjunct to conventional therapy of surgery and antibiotics versus conventional therapy alone. Over the next 24 months, oral lesion size and number, pain, and quality of life were assessed. RESULTS Forty-six patients (mean age, 66 yrs; 57% women) contributed data to the trial. There were no statistically significant differences in the distribution of variables used to assess randomization success between the HBO and standard treatment groups. Seventeen of 25 HBO-treated patients (68%) improved versus 8 of 21 controls (38.1%; P = .043, χ(2) test). Mean time to improvement was 39.7 weeks (95% confidence interval [CI], 22.4 to 57.0 weeks) for HBO-treated patients versus 67.9 weeks (95 CI, 48.4 to 87.5 weeks) for controls (P = .03, log-rank test). However, complete gingival healing occurred in only 14 of 25 HBO-treated patients (52%) versus 7 of 21 controls (33.3%; P = .203, χ(2) test), and time to healing was 59 weeks (95% CI, 42.8% to 75.8%) for HBO-treated patients versus 70 weeks (95 CI, 52.2% to 88.36%) for controls (P = .32, log-rank test). Pain decreased faster for HBO-treated subjects (P < .01, linear regression). Quality-of-life scores for physical health (P = .002) and perceived health (P = .043) decreased at 6 months for control group but for not the HBO group. CONCLUSIONS ONJ is multifactorial and no single treatment modality is likely to reverse it; however, it is treatable and even advanced presentations can improve with intensive multimodal therapy. Clinically, HBO appears to be a useful adjunct to ONJ treatment, particularly for more severe cases, although this study was underpowered to fully support this claim.

Treatment of Cervical Necrotizing Fasciitis with Hyperbaric Oxygen Therapy

Hyperbaric oxygen therapy has significantly improved the management of necrotizing fasciitis of the extremities and trunk. Its role in cervical necrotizing fasciitis has not been fully evaluated. Historically, necrotizing fasciitis has been associated with considerable morbidity and mortality. This report discusses our experience with cervical necrotizing fasciitis in six patients treated from 1986 to 1993 who received hyperbaric oxygen therapy. All patients survived. In all cases infection was of probable odontogenic origin. Most patients in whom necrotizing fasciitis develops have identifiable risk factors; however, two patients in this series were previously healthy, and there was no relationship between hospital course and identified risk factors. Clinical presentation and microbiology are reviewed together with the rationale for hyperbaric oxygen therapy as an adjunct to broad-spectrum antibiotics and aggressive early surgical debridement.

Carbon monoxide, skeletal muscle oxidative stress, and mitochondrial biogenesis in humans

Given that the physiology of heme oxygenase-1 (HO-1) encompasses mitochondrial biogenesis, we tested the hypothesis that the HO-1 product, carbon monoxide (CO), activates mitochondrial biogenesis in skeletal muscle and enhances maximal oxygen uptake (Vo(2max)) in humans. In 10 healthy subjects, we biopsied the vastus lateralis and performed Vo(2max) tests followed by blinded randomization to air or CO breathing (1 h/day at 100 parts/million for 5 days), a contralateral muscle biopsy on day 5, and repeat Vo(2max) testing on day 8. Six independent subjects underwent CO breathing and two muscle biopsies without exercise testing. Molecular studies were performed by real-time RT-PCR, Western blot analysis, and immunochemistry. After Vo(2max) testing plus CO breathing, significant increases were found in mRNA levels for nuclear respiratory factor-1, peroxisome proliferator-activated receptor-gamma coactivator-1alpha, mitochondrial transcription factor-A (Tfam), and DNA polymerase gamma (Polgamma) with no change in mitochondrial DNA (mtDNA) copy number or Vo(2max). Levels of myosin heavy chain I and nuclear-encoded HO-1, superoxide dismutase-2, citrate synthase, mitofusin-1 and -2, and mitochondrial-encoded cytochrome oxidase subunit-I (COX-I) and ATPase-6 proteins increased significantly. None of these responses were reproduced by Vo(2max) testing alone, whereas CO alone increased Tfam and Polgamma mRNA, and COX-I, ATPase-6, mitofusin-2, HO-1, and superoxide dismutase protein. These findings provide evidence linking the HO/CO response involved in mitochondrial biogenesis in rodents to skeletal muscle in humans through a set of responses involving regulation of the mtDNA transcriptosome and mitochondrial fusion proteins autonomously of changes in exercise capacity.

A prospective comparison of a noninvasive cardiac output monitor versus esophageal doppler monitor for goal-directed fluid therapy in colorectal surgery patients

BACKGROUND:Goal-directed fluid therapy (GDFT) is associated with improved outcomes after surgery. The esophageal Doppler monitor (EDM) is widely used, but has several limitations. The NICOM, a completely noninvasive cardiac output monitor (Cheetah Medical), may be appropriate for guiding GDFT. No prospective studies have compared the NICOM and the EDM. We hypothesized that the NICOM is not significantly different from the EDM for monitoring during GDFT. METHODS:One hundred adult patients undergoing elective colorectal surgery participated in this study. Patients in phase I (n = 50) had intraoperative GDFT guided by the EDM while the NICOM was connected, and patients in phase II (n = 50) had intraoperative GDFT guided by the NICOM while the EDM was connected. Each patient’s stroke volume was optimized using 250-mL colloid boluses. Agreement between the monitors was assessed, and patient outcomes (postoperative pain, nausea, and return of bowel function), complications (renal, pulmonary, infectious, and wound complications), and length of hospital stay (LOS) were compared. RESULTS:Using a 10% increase in stroke volume after fluid challenge, agreement between monitors was 60% at 5 minutes, 61% at 10 minutes, and 66% at 15 minutes, with no significant systematic disagreement (McNemar P > 0.05) at any time point. The EDM had significantly more missing data than the NICOM. No clinically significant differences were found in total LOS or other outcomes. The mean LOS was 6.56 ± 4.32 days in phase I and 6.07 ± 2.85 days in phase II, and 95% confidence limits for the difference were −0.96 to +1.95 days (P = 0.5016). CONCLUSIONS:The NICOM performs similarly to the EDM in guiding GDFT, with no clinically significant differences in outcomes, and offers increased ease of use as well as fewer missing data points. The NICOM may be a viable alternative monitor to guide GDFT.

Perfluoropropane Gas as a Magnetic Resonance Lung Imaging Contrast Agent in Humans

BACKGROUND Fluorine-enhanced MRI is a relatively inexpensive and straightforward technique that facilitates regional assessments of pulmonary ventilation. In this report, we assess its suitability through the use of perfluoropropane (PFP) in a cohort of human subjects with normal lungs and subjects with lung disease. METHODS Twenty-eight subjects between the ages of 18 and 71 years were recruited for imaging and were classified based on spirometry findings and medical history. Imaging was carried out on a Siemens TIM Trio 3T MRI scanner using two-dimensional, gradient echo, fast low-angle shot and three-dimensional gradient echo, volumetric, interpolated, breath-hold examination sequences for proton localizers and PFP functional scans, respectively. Respiratory waveforms and physiologic signals of interest were monitored throughout the imaging sessions. A region-growing algorithm was applied to the proton localizers to define the lung field of view for analysis of the PFP scans. RESULTS All subjects tolerated the gas mixture well with no adverse side effects. Images of healthy lungs demonstrated a homogeneous distribution of the gas with sufficient signal-to-noise ratios, while lung images from asthmatic and emphysematous lungs demonstrated increased heterogeneity and ventilation defects. CONCLUSIONS Fluorine-enhanced MRI using a normoxic PFP gas mixture is a well-tolerated, radiation-free technique for regionally assessing pulmonary ventilation. The inherent physical characteristics and applicability of the gaseous agent within a magnetic resonance setting facilitated a clear differentiation between normal and diseased lungs.

Laryngeal Radionecrosis and Hyperbaric Oxygen Therapy: Report of 18 Cases and Review of the Literature

Laryngeal radionecrosis is a difficult late complication of radiotherapy. It is associated with hoarseness, edema, pain, weight loss, and upper airway obstruction. The medical treatment options are limited, and in severe cases, the patient may require tracheostomy or laryngectomy. We report clinical results in 18 patients treated with adjunctive hyperbaric oxygen (HBO) therapy for severe radionecrosis of the larynx. Of these 18 patients, 2 had grade 3 and 16 had grade 4 radionecrosis. The patients received a mean number of 41 HBO treatments (range, 6 to 80) at 2 atmospheres absolute for 2 hours, twice a day, 6 days a week. Thirteen patients (72.2%) had a major improvement after HBO therapy, and none of them required total laryngectomy. All patients preserved their voice and deglutition in good or normal condition. Five patients (27.8%) failed to have a good response to HBO and underwent total laryngectomy. One of these patients had local recurrence of his cancer 4 months later, and the other 3 had significant concurrent medical problems. The remaining patient received only 6 HBO treatments because of emergency heart surgery. These encouraging results are comparable to those of smaller previous studies suggesting that HBO has a beneficial effect in the management of advanced laryngeal radionecrosis.

Treatment of diving emergencies.

Recognition of condition attributable to the environmental changes experienced by divers will facilitate appropriate treatment. The diagnosis of these conditions rarely requires sophisticated imaging or electrophysiologic testing. Divers who have suspected DCI, in addition to general supportive measures, should be administered fluids and oxygen and transported to a recompression chamber. For diving-related conditions, on-line consultation is available from the Divers Alert Network, Durham, NC (919-684-8111).