Effect of drysuit seals on intraocular pressure in non-immersed scuba divers.

Objective: This study quantifies the change in intraocular pressure (IOP) secondary to wearing neck seals in scuba diving drysuits. Previous work demonstrates significant pressures exerted by these seals; we hypothesize that they would. Methods: IOP was measured in 33 divers before and while wearing a drysuit using rebound tonometry. The drysuit neck seal pressures were measured using a manometer. A paired two-sample t-test was used to compare IOP before and after drysuit donning. Pearson correlation coefficients were calculated between neck sealing pressures and IOP by side. Results: The mean IOP in the right eye was similar pre- and post-drysuit donning, with baseline mean 15.9 mmHg (3.7 mmhg) versus 15.4 mmHG (4.3 mmHg) post-donning, p=0.41. Similarly, the mean IOP in the left eye was also similar, with mean pre-donning IOP 15.6 (3.8 mmHg) versus 15.4 mmHg (4.7 mmHg) post-donning, p=0.75. The mean right and left neck seal pressures were 23.66 (10.60) mmHg and 23.67 (7.87) mmHg, respectively. Only the correlation between right neck sealing pressure for silicone neck seals and right IOP, pre- and post-donning was significant (pre: 0.97, p-value 0.03, post: 0.98, p-value 0.02). Conclusion: No significant difference overall was detected in IOP with drysuit donning.

Quantifying drysuit seal pressures in non-immersed scuba divers.

INTRODUCTION: Drysuits use flexible neck and wrist seals to maintain water-tight seals. However, if the seals exert too much pressure adverse physiological effects are possible, including dizziness, lightheadedness, syncope, and paresthesias in the hands. We aimed to quantify the seal pressures of neck and wrist seals in non-immersed divers. METHODS: We recruited 33 diving volunteers at two dive facilities in High Springs, Florida. After a history and physical exam, we measured vital signs as well as wrist and neck seal pressures using a manometer system. RESULTS: The mean (SD) seal pressure of the right wrist seals was found to be 38.8 (14.9) mmHg, while that of the left wrist seals was 37.6 (14.9) mmHg. The average neck seal pressure was 23.7 (9.4) mmHg. Subgroup analysis of seal material demonstrated higher mean sealing pressure with latex seals compared to silicone; however, this difference was not statistically significant. CONCLUSIONS: Drysuit seal pressures are high enough to have vascular implications and even potentially cause peripheral nerve injury at the wrist. Divers should trim their seals appropriately and be vigilant regarding symptoms of excessive seal pressures. Further research may elucidate if seal material influences magnitude of seal pressure.

Delayed recognition of Type II decompression sickness in a diver with chronic atrial fibrillation.

Introduction: This case report describes an initially overlooked Type II decompression sickness (DCS) occurrence that was confused with a cerebral vascular accident in a patient with chronic atrial fibrillation (AF). The purpose of this case report is to reinforce the maxim that DCS needs to be suspected anytime a scuba diver experiences signs or symptoms compatible with DCS after completing a scuba dive. Methods: A 71-year-old scuba diver with a history of AF and who was taking warfarin made four dives, all with maximum depths less than 60 fsw (20 msw) over a 10-hour interval. Shoulder pain developed before entering the water on the fourth dive and was worse after exiting from the fourth dive. Twenty minutes later the diver collapsed while standing and was unable to make a grip using his left hand. A literature review failed to locate any case reports of divers with AF presenting with strokelike symptoms only to find the cause was Type II DCS.. Findings: Initially the patient's findings were reviewed with a diving medicine team. The recommendation was for the patient to be managed for a stroke. The patient was transferred to a hospital for a computed tomography scan, but no recommendation was made for a hyperbaric oxygen recompression treatment. The scan showed no brain bleed or infarct. The attending neurologist (not diving medicine-trained) was concerned that the patient's findings were diving-related and arranged for transferring the patient to a hyperbaric medicine facility 25 hours later. With hyperbaric oxygen (HBO2) therapy the patient's symptoms remitted over several weeks. Conclusion: The presence of symptoms attributed to a stroke immediately after a scuba dive should not deter a trial of HBO2 therapy. The delay in starting HBO2 therapy is concerning and perhaps the reason recovery was delayed and the need for repetitive HBO2 therapies.

Is more complex safer in the case of bail-out rebreathers for extended range cave diving?

Nowhere is redundancy more indispensable than extended range cave diving. Training and practice in this discipline ensure divers are equipped with backup regulators, gauges, lights, and adequate breathing gas for a safe exit, emergencies, and decompression. Depending on penetration distances and depth, open circuit cave diving may require carrying more gas cylinders than can be logistically managed by the diver themselves while maintaining safe gas supply margins. Consequently, divers are forced to either stage cylinders in the cave prior to the dive or rely on resupply from support divers. Both scenarios have significant drawbacks. Due to the improved efficiency of breathing gas utilisation and other advantages, closed circuit rebreathers (CCR) have enabled extended range cave diving. With increasing depths, penetration distances, and bottom times, these divers must also plan for an increasing amount of open circuit bail-out gas in the event of CCR failure. Staged cylinders have traditionally been utilised, but this strategy has limitations due to the advanced dives needed to place them and equipment degradation due to prolonged water immersion, which can often result in cylinder and regulator corrosion with consequent leakage of contents over time. Consequently, a growing number of CCR divers are foregoing open-circuit bailout altogether by carrying an additional CCR system for bailout. Although these bailout rebreathers may facilitate further exploration and have certain advantages, the risks of diving with two complex machines remain to be clearly defined.

Prevention of middle ear barotrauma with oxymetazoline/fluticasone treatment.

Middle ear barotrauma (MEB) is a common complication of hyperbaric oxygen (HBO2) therapy. It has been reported in more than 40% of HBO2 treatments and can interrupt the sequence of HBO2. MEB may lead to pain, tympanic membrane rupture, and even hearing loss. The aim of this study was to determine if pretreatment with intranasal fluticasone and oxymetazoline affected the incidence of MEB. We conducted a retrospective chart review of subjects undergoing HBO2 at our institution between February 1, 2014, and May 31, 2019. Subjects in the fluticasone/oxymetazoline (FOT) treatment group used intranasal fluticasone 50 mcg two times per day and oxymetazoline 0.05% one spray two times per day beginning 48 hours prior to initial HBO2. Oxymetazoline was discontinued after four days. Fluticasone was continued for the duration of HBO2 therapy. A total of 154 unique subjects underwent 5,683 HBO2 treatments: 39 unique subjects in the FOT group underwent 1,501 HBO2; 115 unique subjects in the nFOT (no oxymetazoline or fluticasone treatment) group underwent 4,182 HBO2 treatments. The incidence of MEB was 15.4% in the FOT group and 16.2% in the nFOT group. This was not a statistically significant difference (OR = 0.77; p = 0.636). Treatment pressure, age over 65 years, male sex, and BMI were not associated with a difference in MEB incidence. In summary, pretreatment with intranasal oxymetazoline and fluticasone in patients undergoing HBO2 did not significantly reduce MEB. More investigation with larger numbers of participants and prospective studies could further clarify this issue.

The effectiveness of risk mitigation interventions in divers with persistent (patent) foramen ovale.

INTRODUCTION: Persistent (patent) foramen ovale (PFO) is a recognized risk for decompression sickness (DCS) in divers, which may be mitigated by conservative diving or by PFO closure. Our study aimed to compare the effectiveness of these two risk mitigation interventions. METHODS: This was a prospective study on divers who tested positive for PFO or an atrial septal defect (ASD) and either decided to continue diving without closure ('conservative group'), or to close their PFO/ASD and continue diving ('closure group'). Divers' characteristics, medical history, history of diving and history of DCS were reported at enrollment and annually after that. The outcome measures were the incidence rate of DCS, frequency and intensity of diving activities, and adverse events of closure. RESULTS: Divers in both groups dived less and had a lower incidence rate of confirmed DCS than before the intervention. In the closure group (n = 42) the incidence rate of confirmed DCS decreased significantly. Divers with a large PFO experienced the greatest reduction in total DCS. In the conservative group (n = 23), the post-intervention decrease in confirmed DCS incidence rate was not significant. Of note, not all divers returned to diving after closure. Seven subjects reported mild adverse events associated with closure; one subject reported a serious adverse event. CONCLUSIONS: PFO closure should be considered on an individual basis. In particular, individuals who are healthy, have a significant DCS burden, a large PFO or seek to pursue advanced diving may benefit from closure.

Underwater nasal decongestant use: a novel approach to middle ear equalization.

Middle ear barotrauma is the most common diving-related injury. It is estimated to occur in more than 50% of experienced divers. Although divers learn how to effectively equalize their ears with various maneuvers, airway congestion may impede the ability to equalize the middle ear space via the Eustachian tube. In this case, one may have to avoid diving or abort a dive due to inability to descend. If difficulty with middle ear equalization occurs during the bottom phase of the dive, which may transpire during a multilevel cave or wreck dive, a diver may need to descend before he can exit the water. In this case, it is imperative that the middle ear can be equalized, or one risks middle ear barotrauma, tympanic membrane rupture, possible accrual of decompression and dwindling breathing gas reserves. A 46-year-old diver encountered difficulty with equalization during a cave dive and was able to administer oxymetazoline intranasally to facilitate middle ear equalization. Although effective for this individual,this maneuver is not without risks, which include disorientation, loss of buoyancy, coughing, sneezing, laryngospasm, and a theoretical increased susceptibility to CNS oxygen toxicity.

Efficacy of the U.S. Navy Treatment Tables in treating DCS in 103 recreational scuba divers.

Despite the fact that current decompression schedules reduce the risk of decompression sickness (DCS), recreational scuba divers continue to experience DCS. Therapy outcomes in these divers are difficult to track. Our study aims to understand the efficacy of the United States Navy (USN) Treatment Tables (5, 6, 6A, 9) in providing symptomatic relief among recreational scuba divers. We conducted a single-center retrospective review of recreational divers treated from 2003 to 2013. A total of 187 divers were identified: 84 divers were excluded, and the charts of the remaining 103 divers were independently reviewed by three clinicians. For these 103 divers, the response variable, therapy outcome, was categorized as no relief, partial relief, or complete relief of symptoms. In a population of 76 males and 27 females with an average of three dives and three treatments, 53 patients achieved complete symptomatic relief, 45 patients had partial relief, and five patients reported no relief at the end of all recompression treatments. Among the patients who achieved complete symptomatic relief, 28 (53%) needed only one recompression treatment. The depth of the diver's first dive and the change in symptoms within the first 20 minutes of the first recompression treatment were found to be explanatory variables of the treatment outcome.

Characteristics of Ocular Pain Complaints in Patients With Idiopathic Dry Eye Symptoms.

OBJECTIVE: The purpose of this study was to examine the severity and quality of ocular pain complaints in patients with dry eye symptoms. METHODS: Subjects with clinically relevant dry eye symptoms (dryness, discomfort, tearing) of unknown origin seen in the Miami Veterans Affairs eye clinic were administered questionnaires for dry eye symptoms and ocular pain and underwent a standardized ocular examination. Qualities and severity ratings of ocular pain in subjects with idiopathic dry eye were compared with similar measures from published data in other chronic pain populations. RESULTS: The study sample consisted of 154 subjects, of which 91% were men and ranged in age from 27 to 89 (mean age=61). Fifty-three percent of participants reported an average ocular pain of at least moderate intensity (numerical rating scale≥4), with specific characteristics (i.e., "burning" spontaneous pain) reported at frequencies comparable to prevalent chronic neuropathic pain syndromes as reported in the literature. Significant correlations were found between ocular pain metrics and dry eye symptom severity scores (r=0.57-0.66). Dry eye signs, however, did not generally correlate with ocular pain severity. CONCLUSIONS: A significant proportion of subjects with idiopathic dry eye symptoms reported moderate or greater ocular pain intensity, with most endorsing descriptors commonly used by patients with nonocular neuropathic pain conditions. Identifying subgroups of dry eye patients based on the presence and characteristics of ocular pain complaints may improve dry eye subclassification and better individualize treatment strategies.

Assessment of Somatosensory Function in Patients With Idiopathic Dry Eye Symptoms.

IMPORTANCE: Somatosensory dysfunction likely underlies dry eye (DE) symptoms in many individuals yet remains an understudied component of the disease. Its presence has important diagnostic and therapeutic implications. OBJECTIVE: To assess the integrity of nociceptive system processes in persons with DE and ocular pain using quantitative sensory testing (QST) techniques applied at a site remote from the eye. DESIGN, SETTING, AND PARTICIPANTS: A cross-sectional study conducted at Miami Veterans Affairs Hospital included 118 individuals with a wide variety of DE symptoms and signs. The study was conducted from October 31, 2013, to January 28, 2016. INTERVENTIONS: Individuals completed questionnaires regarding ocular symptoms (5-Item Dry Eye Questionnaire [DEQ5], Ocular Surface Disease Index [OSDI], and Neuropathic Pain Symptom Inventory modified for the eye [NPSI-E]), psychological status, and medication use and underwent an ocular surface examination. The QST metrics included measures of vibratory and thermal thresholds and cold and hot pain temporal summation (surrogate measures of central sensitization) on the forearm. MAIN OUTCOMES AND MEASURES: Correlations among DE and ocular pain symptom severity with QST metrics measured on the forearm. The OSDI score ranges from 0 to 100, with 100 indicating the most severe DE symptoms. The DEQ5 score ranges from 0 to 22, with the highest score indicating the most severe symptoms, and the NPSI-E score ranges from 0 to 100, with the highest score indicating the most severe symptoms. Psychological state was measured with the 9-item Patient Health Questionnaire, the PTSD Checklist-Military Version for PTSD, and the Symptom Checklist-90 for anxiety. RESULTS: Of the 118 patients who participated in the study, 105 (88.9%) were men (mean [SD] age, 60 [10] years), and a mean of 41% had PTSD, 10% depression, and 0.93% anxiety. Using stepwise linear regression analyses, significant associations were identified between overall DE symptom severity and posttraumatic stress disorder scores and tear breakup time (DEQ5 model: R = 0.54; OSDI model: R = 0.61, P < .001). All other variables (ie, demographics, comorbidities, medications, tear film factors, and QST metrics) dropped out of these models. When specifically considering neuropathic-like qualities of DE pain, however, anxiety and hot pain temporal summation at the forearm explained 17% of the variability in ocular burning (R = 0.41; P < .001), and PTSD score, tear breakup time, and hot pain temporal summation at the forearm explained 25% of the variability in sensitivity to wind (R = 0.50; P < .001) and 30% of the variability in total NPSI-E scores (R = 0.55; P < .001). CONCLUSIONS AND RELEVANCE: Our findings demonstrate that neuropathic-like DE pain symptom severity correlates with quantitative measures of pain sensitivity at a site remote from the eye. This result provides additional evidence that DE symptoms are not only manifestations of a local disorder but also involve somatosensory dysfunction beyond the trigeminal system.

Neuropathic Ocular Pain due to Dry Eye is Associated with Multiple Comorbid Chronic Pain Syndromes.

UNLABELLED: Recent data show that dry eye (DE) susceptibility and other chronic pain syndromes (CPS) such as chronic widespread pain, irritable bowel syndrome, and pelvic pain, might share common heritable factors. Previously, we showed that DE patients described more severe symptoms and tended to report features of neuropathic ocular pain (NOP). We hypothesized that patients with a greater number of CPS would have a different DE phenotype compared with those with fewer CPS. We recruited a cohort of 154 DE patients from the Miami Veterans Affairs Hospital and defined high and low CPS groups using cluster analysis. In addition to worse nonocular pain complaints and higher post-traumatic stress disorder and depression scores (P < .01), we found that the high CPS group reported more severe neuropathic type DE symptoms compared with the low CPS group, including worse ocular pain assessed via 3 different pain scales (P < .05), with similar objective corneal DE signs. To our knowledge, this was the first study to show that DE patients who manifest a greater number of comorbid CPS reported more severe DE symptoms and features of NOP. These findings provided further evidence that NOP might represent a central pain disorder, and that shared mechanistic factors might underlie vulnerability to some forms of DE and other comorbid CPS. PERSPECTIVE: DE patients reported more frequent CPS (high CPS group) and reported worse DE symptoms and ocular and nonocular pain scores. The high CPS group reported symptoms of NOP that share causal genetic factors with comorbid CPS. These results imply that an NOP evaluation and treatment should be considered for DE patients.

A favorable outcome despite a 39-hour treatment delay for arterial gas embolism: case report.

Cerebral arterial gas embolism (CAGE) occurs when gas enters the cerebral arterial vasculature. CAGE can occur during sitting craniotomies, cranial trauma or secondary to gas embolism from the heart. A far less common cause of CAGE is vascular entrainment of gas during endoscopic procedures. We present the case of a 49-year-old male who developed a CAGE following an esophagoduodenoscopy (EGD) biopsy. Due to a delay in diagnosis, the patient was not treated with hyperbaric oxygen (HBO2) therapy until 39 hours after the inciting event. Despite presenting to our institution non-responsive and with decorticate posturing, the patient was eventually discharged to a rehabilitation facility, with only mild left upper extremity weakness. This delay in HBO2 treatment represents the longest delay in treatment to our knowledge for a patient suffering from CAGE secondary to EGD. In addition to the clinical case report, we discuss the etiology of CAGE and the evidence supporting early HBO2 treatment, as well as the data demonstrating efficacy even after considerable treatment delay.

Outcomes in pediatric patients with Chiari malformation Type I followed up without surgery.

OBJECT: The natural history of untreated Chiari malformation Type I (CM-I) is poorly defined. The object of this study was to investigate outcomes in pediatric patients with CM-I who were followed up without surgical intervention. METHODS: The authors retrospectively reviewed 124 cases involving patients with CM-I who presented between July 1999 and July 2008 and were followed up without surgery. The patients ranged in age from 0.9 to 19.8 years (mean 7 years). The duration of follow-up ranged from 1.0 to 8.6 years (mean 2.83 years). Imaging findings, symptoms, and findings on neurological examinations were noted at presentation and for the duration of follow-up. RESULTS: The mean extent of tonsillar herniation at presentation was 8.35 mm (range 5-22 mm). Seven patients had a syrinx at presentation. The syrinx size did not change in these patients on follow-up imaging studies. No new syrinxes developed in the remaining patients who underwent subsequent imaging. The total number of patients with presenting symptoms was 81. Of those 81 patients, 67 demonstrated symptoms that were not typical of CM-I. Of the 14 patients with symptoms attributed to CM-I, 9 had symptoms that were not severe or frequent enough to warrant surgery, and surgery was recommended in the remaining 5 patients. Chiari malformation Type I was also diagnosed in 43 asymptomatic patients who had imaging studies performed for various reasons. No new neurological deficits were noted in any patient for the duration of follow-up. CONCLUSIONS: The majority of patients with CM-I who are followed up without surgery do not progress clinically or radiologically. Longer follow-up of this cohort will be required to determine if symptoms or new neurological findings develop over the course of many years.