Digital Pulse Oximetry Research Articles

Reliability of Digital Artery Palpation and Pulse Oximetry Waveform As Alternatives to Radial Pulse in the Assessment of Upper Limb Injuries.

Radial pulse palpation is widely accepted as a gold standard clinical method to assess distal vascular perfusion of the upper limb. In some instances, the radial pulse may not be accessible due to splints, casts, or swelling, or the injury may be at the level or distal to the radial artery. Here, the authors assess two alternative methods of assessing perfusion of the hand more distally: palpation of the digital pulse and pulse oximetry (PO) waveform. Twenty-four healthy adult volunteers (48 hands) were assessed by two assessors. Digital artery pulses were palpated, and ease of location was recorded. A brachial cuff pressure was inflated to 20 mmHg above systolic pressure to occlude distal perfusion. Radial pulse, digital artery pulse, and PO waveform were monitored as the brachial cuff pressure was deflated in 5 mmHg increments to ascertain when each returned and compare the reliability of these tests to the gold standard of the radial pulse. The digital artery pulse was easily located in 20/24 participants, most reliably over the proximal phalanx of the index finger. With occlusion of the brachial artery, no distal pulses could be felt, and PO showed no waveform. As the brachial artery cuff pressure was incrementally deflated, the digital pulse returned with the same cuff pressure or a lower cuff pressure than the radial pulse in all cases, suggesting a high positive predictive value of radial pulse presence. PO waveform returned at a higher cuff pressure or with the same cuff pressure as the return of the radial pulse, suggesting a higher sensitivity than radial pulse palpation in assessing hand perfusion. Digital pulse palpation can be used as a surrogate method of assessing hand perfusion. When present, it can be assumed a radial pulse is present due to a high positive predictive value and no false positives seen in any participant. When absent, further investigation is required. The PO waveform was found to be more sensitive than digital or radial pulse palpation as a measure of distal perfusion, with a return of waveform prior to palpable pulses. This likely represents a more accurate clinical test of distal perfusion and can be relied upon even when pulses are not palpable.

Kematian Akibat Prolonged Hipoksia pada Status Epileptikus

Status epilepticus (SE) is a condition that results from the failure of the mechanisms responsible for seizure cessation or from the initiation of mechanisms, leading to prolonged seizures. This is a condition that can have long-term effects (especially if the duration is >30 minutes) such as death, injury, and changes in neuronal tissue depending on the type and duration of the seizure. The human brain consumes a very disproportionate amount of energy given its relatively small size, thus requiring a system capable of balancing cellular oxygen metabolism and brain blood flow control in order to maintain brain oxygen levels. Seizures have been shown to cause changes in oxygen levels beyond the normoxic range, which increases the likelihood that seizure-induced changes in brain pO2 may affect brain function during and after seizures. Decreased oxygenation is common during epileptic seizures. This has been seen on digital pulse oximetry (which measures oxygenation of either the fingers or toes) in the 25-33% saturation range when they have seizures. Such hypoxemia is more common in seizures that are generalized (ie begin as or become generalized tonic-clonic seizures) and/or prolonged.

Role of laparoscopic lumbar sympathectomy in chronic limb-threatening ischemia due to nonreconstructable peripheral arterial disease

Background Lumbar sympathectomy (LS) was traditionally performed for intermittent claudication but is now eclipsed by revascularization for that indication. However, it retains a role in the management of chronic limb-threatening ischemia and other conditions causing lower limb pain with or without ischemia. In this study, we identify its role in the management of chronic limb-threatening ischemia in cases of nonreconstructable peripheral arterial disease. Aim The main aim of this study is to determine if LS procedure has an effective role in limb salvage and pain control for patients with nonreconstructable peripheral limb ischemia. The primary endpoint was limb salvage in the target limb, while the secondary endpoint targeted assessment of pain improvement in the same limb. Patients and methods This study is a prospective single-arm cohort study conducted using 21 patients between the January 1, 2021 and the January 1, 2023 at two hospitals, Ain Shams University Hospital and Nasser Institute Hospital. Patients complained of nonreconstructable peripheral arterial disease and there was no chance for revascularization either endovascular or surgical bypass. Results This study included 60 patients; one patient was excluded due to being lost to follow-up, and presented with nonconstructable critical limb ischemia between the January 1, 2021 and the January 1, 2023. There were 42 (70%) males and 18 (30%) females. Follow-up for all patients was subjected to measurement of ankle brachial pressure index, digital pulse oximetry, toe pressure and numerical rating scale for pain scoring preoperative and postoperative. On follow-up we noticed that there was no change in either ankle brachial pressure index or toe pressure immediately postoperatively and after 12 months. However, the digital pulse oximetry showed significant improvement immediately postoperatively from 68.40±7.36 to 81.15±12.23 with a P value of 0.001. The most remarkable improvement was found in pain scoring immediately, 1, 3, 6, and 12 months postoperatively with P values showing statistical significance. As for limb salvage, there was a 100% limb survival for 3 months. After 6 months, only nine cases underwent above-knee amputation, one of them was due to severe limb infection, and three cases had minor amputation ‘toe amputation.’ We noticed that three out of the nine cases suffering major amputations had femoropopliteal disease. Of the patients, 80% suffered no minor or major amputation, while 15% had major amputations beyond the tarsometatarsal joint and only 5% underwent minor toe amputation or debridement. Fortunately, there was no mortality among the studied cases. Conclusion Retroperitoneoscopic LS is significantly less invasive than open surgical technique with fewer wound complications and less hospital stay period and offers a longer duration of pain relief and less incidence of recurrence of manifestations.

The Iatrogenic Injury Potential of Self-adherent, Elastic Bandages in Finger Injuries.

The use of a self-adherent, elastic bandage is a practical way to dress finger injuries. Multiple reports describe iatrogenic injuries from elastic bandages, ranging from skin necrosis to finger gangrene, necessitating amputations. This study investigated whether elastic bandages can compromise digital perfusion by occluding arterial blood flow in healthy volunteers and evaluated the utility of pulse oximetry as a monitoring tool for digital perfusion. A technique for safe bandage application is proposed. A commercially available elastic bandage was wrapped around the index finger of 20 healthy volunteers at varying degrees of stretch. Digital perfusion measurements were carried out using photoelectric pulse transduction, laser Doppler flowmetry, and pulse oximetry. Intracompartmental pressure measurements were recorded using a separate in vitro experimental model. Elastic bandages applied at maximum stretch did not change digital brachial index or pulse oximetry values, suggesting arterial blood flow was preserved distal to the bandage. Intracompartmental pressure measurements at maximum stretch remained below the systolic digital pressure. In contrast, superficial dermal perfusion fell to 32% of normal as measured by laser Doppler flow, at 100% bandage stretch. This study suggests a risk for iatrogenic injury when using elastic bandages for finger dressings. While arterial inflow was never compromised, pressures were high enough to occlude superficial venous outflow, which may begin at 20% bandage stretch. Pulse oximetry failed to detect changes distal to applied dressings, and we do not recommend it to detect digital vascular compromise in this setting.

Effect Of Surgical And N95 Facial Masks On Exercise Tolerance, Heart Rate, Respiratory Rate And Blood Oxygen Saturation

Background — Although wearing masks is inevitable these days, the effects of wearing them on physiologic parameters have not been reported. This study aimed to assess the effects of wearing no mask, a three-layer standard surgical mask, and wearing an N95 mask on blood oxygen saturation, aerobic tolerance, and performance during exercise. Methods — Twenty-one participants were enrolled in the study. Each participant was monitored with electrocardiography (ECG) while performing an exercise tolerance test using the Bruce treadmill protocol. Testing was conducted three times on different dates. Participants did not use any mask in the first test but did wear surgical and N95 masks during the second and third tests respectively. Respiratory rate (RR) was assessed for 10 seconds and then multiplied by 6. Heart rate (HR) was monitored by ECG, and oxygen saturation levels were monitored (O2Sat) via digital pulse-oximetry. Assessments were done before warm-up, at the middle and end of each Bruce stage, and as well at 1, 2, and 5 minutes into recovery (masks were worn during recovery). Results — HR, RR, and O2Sat measured data were all significantly different between the three trials at end-stage 3 of Bruce treadmill protocol (p<0.05). Although HR was still higher through the recovery period in the N95 trial in comparison with other trials (p<0.05), RR and O2Sat measured data were not different in the recovery phase. Conclusion — HR, RR, O2Sat and exercise tolerance are significantly affected by wearing surgical and N95 masks.

Identifying Trends of Dysautonomia Signs and Symptoms Associated with Protracted Concussion Recovery during the Buffalo Concussion Treadmill Test: A Retrospective Study

Abstract Objective: To identify trends of provoked dysautonomia signs and symptoms during the Buffalo Concussion Treadmill Test (BCTT). Subjects: This is a retrospective cohort study of 101 patient charts post-concussion who were screened for suspected dysautonomia. Methods: Patients with suspected dysautonomia were assessed for exercise intolerance using a BCTT. Symptoms and rate of perceived exertion were recorded on a standardized form. Digital pulse oximetry was used to collect heart rate (HR) and oxygen saturation. Descriptive analyses were conducted on BCTT results. Results: Of 101 patient charts, 57 were excluded from analysis, including four patients who completed the BCTT by asymptomatically reaching the target HR zone for their estimated HR max. The remaining 44 patients demonstrated: 35 (79.5%) poor HR stabilization defined as a drop or plateau in HR during exercise, 28 (63.8%) exacerbated concussion symptoms, 13 (29.5%) autonomic nervous system response such as hot flushed sensation, 12 (27.3%) rebound symptoms during recovery phases, and 8 (18.2%) desaturation of 90% or below. The mean delta (80% expected HR max – 80% achieved HR max) on the initial test was 80.66 (± 23.08) beats per minute. Conclusions: This study is the first to identify trends of signs and symptoms during the BCTT in an expanded population with suspected dysautonomia after concussion. Future studies are indicated to validate these findings and contribute to development of modified termination criteria for the BCTT in individuals with suspected dysautonomia associated with protracted concussion recovery.

Identifying Trends of Dysautonomia Signs and Symptoms Associated with Protracted Concussion Recovery during the Buffalo Concussion Treadmill Test: A Retrospective Study

Objective: To identify trends of provoked dysautonomia signs and symptoms during the Buffalo Concussion Treadmill Test (BCTT). Subjects: This is a retrospective cohort study of 101 patient charts post-concussion who were screened for suspected dysautonomia. Methods: Patients with suspected dysautonomia were assessed for exercise intolerance using a BCTT. Symptoms and rate of perceived exertion were recorded on a standardized form. Digital pulse oximetry was used to collect heart rate (HR) and oxygen saturation. Descriptive analyses were conducted on BCTT results. Results: Of 101 patient charts, 57 were excluded from analysis, including four patients who completed the BCTT by asymptomatically reaching the target HR zone for their estimated HR max. The remaining 44 patients demonstrated: 35 (79.5%) poor HR stabilization defined as a drop or plateau in HR during exercise, 28 (63.8%) exacerbated concussion symptoms, 13 (29.5%) autonomic nervous system response such as hot flushed sensation, 12 (27.3%) rebound symptoms during recovery phases, and 8 (18.2%) desaturation of 90% or below. The mean delta (80% expected HR max – 80% achieved HR max) on the initial test was 80.66 (± 23.08) beats per minute. Conclusions: This study is the first to identify trends of signs and symptoms during the BCTT in an expanded population with suspected dysautonomia after concussion. Future studies are indicated to validate these findings and contribute to development of modified termination criteria for the BCTT in individuals with suspected dysautonomia associated with protracted concussion recovery.

Identifying Trends of Dysautonomia Signs and Symptoms Associated with Protracted Concussion Recovery during the Buffalo Concussion Treadmill Test: A Retrospective Study

Objective: To identify trends of provoked dysautonomia signs and symptoms during the Buffalo Concussion Treadmill Test (BCTT). Subjects: This is a retrospective cohort study of 101 patient charts post-concussion who were screened for suspected dysautonomia. Methods: Patients with suspected dysautonomia were assessed for exercise intolerance using a BCTT. Symptoms and rate of perceived exertion were recorded on a standardized form. Digital pulse oximetry was used to collect heart rate (HR) and oxygen saturation. Descriptive analyses were conducted on BCTT results. Results: Of 101 patient charts, 57 were excluded from analysis, including four patients who completed the BCTT by asymptomatically reaching the target HR zone for their estimated HR max. The remaining 44 patients demonstrated: 35 (79.5%) poor HR stabilization defined as a drop or plateau in HR during exercise, 28 (63.8%) exacerbated concussion symptoms, 13 (29.5%) autonomic nervous system response such as hot flushed sensation, 12 (27.3%) rebound symptoms during recovery phases, and 8 (18.2%) desaturation of 90% or below. The mean delta (80% expected HR max – 80% achieved HR max) on the initial test was 80.66 (± 23.08) beats per minute. Conclusions: This study is the first to identify trends of signs and symptoms during the BCTT in an expanded population with suspected dysautonomia after concussion. Future studies are indicated to validate these findings and contribute to development of modified termination criteria for the BCTT in individuals with suspected dysautonomia associated with protracted concussion recovery.

Preventive home therapy for symptomatic patients affected by COVID-19 and followed by teleconsultations.

In this paper we present our experience on the treatment at home of Covid+ symptomatic patients. One hundred and eighty-two subjects (111 men and 71 women) aged from 32 to 71 years have been consecutively followed at home in telemedicine from 1st September to 24th December 2020. We were informed almost twice daily in morning and evening about body temperature, symptoms (cough, shortness of breath or difficulty breathing, fatigue, muscle of body aches, headache, loss of taste or smell, sore throat, congestion or runny nose, nausea and vomiting, diarrhea), oxygen saturation measured by digital pulse oximetry and blood pressure. Our protocol of treatment was based on early use of prednisone (25 mg in the morning and 12.5 mg in the afternoon) and low molecular weight heparin (4000 UI one or two times daily) initiated just after the positivity of molecular nasopharyngeal test (about 3-4 days as mean time after initiation of symptomatology and not after 7-8 days as suggested by other protocols) and oxygen therapy when necessary. Antibiotics such as azithromycin for six days was added. It is always recommended to associate lansoprazole 30 mg to prevent gastric hemorrhages and potassium and magnesium supplements. This treatment scheme was able to reduce the risk of hospitalization as only 4 patients needed to be admitted to the Hospital, and only two in subintensive department. After negativeness of molecular nasopharyngeal test, patients were invited for a thoracic computerized tomography and laboratory evaluation of d-dimer and other data of inflammation to show eventual lung interstitial involvement characteristic of COVID-19.

To determine if digital pulse oximetry is an acceptable screening tool for asymptomatic peripheral vascular disease in type 2 diabetes mellitus: An observational study

Methods: The present analytical cross-sectional study was carried out among 80 patients of type 2 Diabetes Mellitus with asymptomatic PVD were included. The diagnostic accuracy of Ankle-Brachial Index (ABI) and pulse oximetry as a screening tool was compared against Color Doppler ultrasonography as the reference standard.

Falsely low values of oxygen saturation measured by pulse oximetry in patients with coronavirus disease 2019.

Sir, Digital pulse oximetry is a rapid noninvasive test and is used to estimate arterial oxygen saturation. However, falsely low readings are common due to a range of causes including motion artifact, hypotension, nail polish, darker skin pigmentation, and venous pulsations. We recently encountered a number of patients with coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with falsely low oxygen saturation detected by digital pulse oximetry. Following the first confirmed COVID-19 case on March 11 in Turkey, our hospital started to serve as a coronavirus pandemic hospital on April 1, 2020. Three hundred and forty-five patients were hospitalized to Istanbul University of Health Sciences Gaziosmanpasa Research and Training Hospital between April 1, 2020, and April 14, 2020. Among these, we identified 17 patients who had a discordance of oxygen saturation measured by digital pulse oximetry and arterial blood gas analysis. This study was approved by our institutional ethics committee (Approvement protocol number: 58/06.05.2020). The mean (standard deviation [SD]) age was 65.7 ± 17.0 years, and 10 of 17 patients (58.8%) were men. Nine of these 17 patients had fever. Hypotension and tachycardia were not observed in all the patients. Laboratory parameters showed elevated aspartate transaminase (median: 46 U/L, interquartile range [IQR]: 34–58), ferritin (median: 447 ng/mL, IQR: 237–1119), D-dimer (median: 1062 ng/mL, IQR: 774–1387), C-reactive protein (mean ± SD: 141.4 ± 103.1 mg/L), fibrinogen levels (mean ± SD: 382.6 ± 72.0 mg/dL), and low lymphocyte count (mean ± SD: 790 ± 409 cells/μL). The findings of oxygen saturation levels measured by pulse oximetry and arterial blood gas analysis are shown in Table 1. Repeated measurements of oxygen saturation by different pulse oximetry devices were still falsely low in all the patients. Hypertension and chronic ischemic heart disease were the most common comorbidities. In addition, one of them was diagnosed with acute pulmonary thromboembolism. Eleven patients were treated by therapeutic dose enoxaparin, whereas 6 were treated by prophylactic dose enoxaparin. Among the 17 patients, 8 (47%) remained hospitalized at the final study follow-up date, 7 (41.1%) were discharged alive, and the remaining 2 (11.9%) were transferred to the intensive care unit.Table 1: Findings of oxygen saturation measured by pulse oximeter and arterial blood gasThe relationship between inflammation due to viral infection and hypercoagulation has already been known.[1] Similarly, extensive intravascular microthrombosis was observed in autopsy series including four deceased cases with COVID-19.[2] Endothelial cell involvement has been suggested a possible reason for impaired microcirculatory function in different vascular beds.[34] Ciceri et al. have recently proposed a new hypothesis called “microvascular COVID-19 lung vessels obstructive thromboinflammatory syndrome (MicroCLOTS).”[5] This hypothesis was based on the following findings. First, SARS-CoV-2 enters into endothelial cell through the receptor angiotensin-converting enzyme 2. Second, replication of the virus causes release of pro-inflammatory cytokines and activation of macrophages and the complement cascade in endothelial cells. Activation of complement cascade triggers further immune response, tissue injury, and microvascular thrombosis. Third, the progression of endothelial damage with microvascular thrombosis can spread locally in the lung and potentially extends to the microvascular bed of several organs. In our case series, all of the patients were hemodynamically stable and had no clinical sign of hypoperfusion. In addition, none of the patients had anemia, hypothermia, nail polish, pigmented skin, dyshemoglobinemia, and hyperbilirubinemia that may cause misconceptions in reporting oxygen saturation. Although inappropriate placement of pulse oximeter probe may be a limitation of our observation, repeated measurements by different pulse oximetry devices were consistent. We suggest that discordance between pulse oximeter and arterial blood gas analysis may also indicate widespread microvascular thrombosis, not limited to the lung, and may further support MicroCLOTS hypothesis. Moreover, oxygen saturation is an essential monitoring tool in the management of COVID-19. Some patients may experience silent hypoxemia,[6] and there is an ongoing discussion whether pulse oximetry screening at home could provide an early warning system for COVID-19 pneumonia. However, arterial blood gas analysis seems to be more appropriate to assess arterial oxygen saturation. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Circumferential Negative Intermittent Pressure to the Midarm Does Not Impair Digital O2 Saturation: A Randomized Controlled Study.

Circumferential negative pressure wound therapy is commonly used to manage wounds and enhance the healing process. A theoretical concern was recently raised that circumferential negative pressure wound therapy may have a negative effect on perfusion distally. In a randomized study, we applied circumferential negative pressure (125 mm Hg) to the midarm of 13 healthy volunteers through InfoV.A.C. Therapy Unit device. The pressure was applied intermittently (5 minutes on and 2 minutes off) for 9 hours. The same device without negative pressure was applied to the contralateral midarm as control. Bilateral index finger O2 saturation (SpO2) was measured every 30 minutes using digital pulse oximetry. Mean (SD) age of the volunteers was 32.2 (9.5) years, and 61.5% were male. Mean (SD) area under the curve from time 0 to 9 hours of SpO2 was 890.56 (6.69) and 889.71 (6.23) %xh in the intervention and control arms, respectively (P = 0.35). O2 saturation was ≥94% at all observation times in both arms, and no adverse events were identified. Circumferential negative intermittent pressure of 125 mm Hg applied to the midarm of healthy volunteers for 9 hours does not adversely affect digital SpO2.

Pulse Oximetry as a Screening Test for Hemodynamically Significant Lower Extremity Peripheral Artery Disease in Adults with Type 2 Diabetes Mellitus.

ObjectiveThe main objective is to determine if digital pulse oximetry is an acceptable screening tool to detect hemodynamically significant lower extremity peripheral artery disease (PAD) in patients 50 years old and above with type 2 diabetes mellitus (T2DM) seen at the University of Santo Tomas Hospital (USTH).MethodologyA total of 78 subjects (155 limbs) were included. Using duplex ultrasonography as the reference standard for the presence of hemodynamically significant lower extremity PAD, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were obtained for abnormal percent oxygen saturation (SpO2) gradients and for ankle-brachial index (ABI).ResultsOf the 155 limbs, 38.7% had hemodynamically significant stenosis. Pulse oximetry had 76.7% sensitivity (95% CI, 65.2% to 88.1%), 85.3% specificity (95% CI, 78.0% to 92.6%), 76.7% PPV (95% CI, 66.5% to 84.4%) and 85.3% NPV (95% CI, 78.4% to 90.2%). ABI had 40.7% sensitivity (95% CI, 30.1% to 51.3%), 88.2% specificity (95% CI, 80.0% to 96.3%), 68.6% PPV (95% CI, 53.6% to 80.4%) and 70.1% NPV (95% CI, 65.1% to 74.5%). Combining both produces 88.1% sensitivity (95% CI, 78.5% to 97.8%), 74.2% specificity (95% CI, 65-83.4%), 68.4 PPV (95% CI, 60.3% to 75.6%) and 90.8% NPV (95% CI, 83.0% to 95.2%).ConclusionThe results of this study suggest that pulse oximetry has a higher sensitivity than ABI as a screening tool for hemodynamically significant lower extremity PAD in T2DM patients 50 years old and above. Combining these two tests may be done to achieve a higher sensitivity.

Sleep-disordered breathing, neuroendocrine function, and clinical SUDEP risk in patients with epilepsy

IntroductionSudden unexpected death in epilepsy (SUDEP) is a major contributor to epilepsy-related mortality. It is associated with nocturnal seizures and centrally mediated postictal cardiorespiratory dysfunction (CRD), but mechanisms and contributors remain poorly understood. MethodsWe performed a prospective, cross-sectional, observational pilot study in the Columbia University Medical Center (CUMC) adult epilepsy monitoring unit (EMU) to explore relationships between periictal CRD, sleep-disordered breathing (SDB), neuroendocrine function, and clinical SUDEP risk. Thirty patients (twenty women, ten men) underwent video-electroencephalogram (EEG) with electrocardiogram (EKG) and digital pulse oximetry, inpatient or outpatient polysomnography (PSG), and comprehensive laboratory evaluation of sex steroid hormones. Sudden unexpected death in epilepsy risk was defined as Low (0–2) or High (≥3) using the revised SUDEP-7 Inventory. Sleep-disordered breathing was defined using standard criteria. Neuroendocrine dysfunction was defined as ≥1 laboratory abnormality. ResultsCardiorespiratory dysfunction occurred more frequently in high-risk patients (60% vs. 27%, p = 0.018). Endocrine dysfunction was seen in 35% of patients, more in men (p = 0.018). Sleep-disordered breathing was found in 88% of fully scoreable PSGs. ConclusionsThere was no significant relationship between CRD, SDB, and neuroendocrine status, though all PSGs in those with high SUDEP risk or neuroendocrine dysfunction revealed SDB. Larger studies are needed to further elucidate relationships between CRD, SDB, neuroendocrine factors, and SUDEP.

Digital Pulse Oximetry for the Screeing of Lower Extremity Arterial Disease

Digital Pulse Oximetry for the Screeing of Lower Extremity Arterial Disease

Digital and forehead pulse oximetry in Intensive Care Unit. A comparison

Pulse oximetry is now a widely available technology that provides easy and continuous reliable measurements of oxygen saturation, the percentage of O2 bound to Hb (SpO2). Pulse oximetry has become a standard monitoring not only in intensive care, but also in other clinical settings, although several factors can interfere with a correct reading, as low perfusion conditions, such as low cardiac output, vasoconstriction, hypothermia. We performed a prospective observational study in two groups of twenty-eight patients admitted to the ICU, in which we compared the values ​​obtained (SpO2) with digital and forehead pulse oximetry, with arterial oxygen saturation (SaO2) obtained from blood gas analysis (EGA). Comparison measurements into two distinct groups, though homogeneous might be a limitation of the study, but at the same time provide a representative picture of a polyvalent intensive care unit. The result was that both the values ​​obtained with digital and frontal pulse oximetry are accurate and reliable in comparison to EGA. In situations of hypoxia, the reliability of frontal pulse oximetry appears superior compared to digital oximetry.

Periictal cerebral tissue hypoxemia: A potential marker of SUDEP risk

Cerebral oximetry has not been explored in patients experiencing seizures in the epilepsy monitoring unit (EMU). The purpose of our study was to evaluate the feasibility of periictal measurement of cerebral oxygenation using noninvasive cerebral tissue oximetry and to determine whether there was evidence of cerebral hypoxemia during generalized seizures. Cerebral oxygen saturation findings were subsequently correlated with sudden unexpected death in epilepsy (SUDEP) risk factors. We prospectively evaluated six patients admitted to our EMU with histories of generalized tonic-clonic seizures (GTCS) with prolonged scalp electroencephalography (EEG) and two regional cerebral oxygen saturation (rSO(2)) sensors. Minimum rSO(2) values were recorded in the 5 min preceding seizure onset, during the seizure, and in the 5 min following seizure offset. SUDEP risk was assessed using the SUDEP-7 Inventory. Cerebral oximetry was well tolerated, with a mean duration of rSO(2) monitoring of 81.1 h. Cerebral oxygen saturation data were available from at least one sensor in 9 (90%) of 10 seizures; only 6 (60%) of 10 seizures had useable periictal digital pulse oximetry data. GTCS were associated with significantly lower minimum ictal (p = 0.003) and postictal (p = 0.004) %rSO(2) values than the minimum preictal value. Patients with at least one seizure with a %rSO(2) decrease of ≥20% tended to have higher SUDEP-7 Inventory scores (mean SUDEP-7 Inventory score 7 ± 2.8) versus patients without recorded desaturations (4.3 ± 0.5, p = 0.08). Larger studies are needed to determine the value of cerebral oximetry in the identification of patients at risk of SUDEP.

Assessment of collateral circulation to the hand prior to radial artery harvest

Assessment of collateral circulation to the hand is required prior to invasive procedures or harvesting of the radial artery (RA). A modified Allen's test (MAT) is commonly used to assess palmar arch collaterals. A variety of non-invasive methods including digital pressures, plethysmography, pulse oximetry and duplex ultrasonography are available to supplement physical examination. However, no consensus exists about the proper role of the MAT and the most appropriate non-invasive test (NIT) in this situation. Interpretation of the MAT and NIT findings are also controversial. This paper reviews the anatomy and the physiologic basis for the MAT and various NITs, the pros and cons of various NITs and recommendations for the assessment of collateral circulation to the hand prior to interventions directed at the RA.

Relation of the Severity of Obstructive Sleep Apnea in Response to Anti-Arrhythmic Drugs in Patients With Atrial Fibrillation or Atrial Flutter

Atrial fibrillation (AF) is more common in those with obstructive sleep apnea (OSA) than in unaffected subjects and recurs more frequently in the presence of severe OSA after electrical cardioversion and AF ablation. However, it is unknown whether the severity of OSA influences the efficacy of antiarrhythmic drug (AAD) therapy in patients with OSA and AF. The aim of this study was to examine the impact of OSA severity on the treatment of patients with symptomatic AF using AADs. Sixty-one patients (mean age 62 ± 15 years, 21 women) treated with AADs for symptomatic AF who underwent overnight polysomnography were studied. Rhythm control was prospectively defined as successful if a patient remained on the same AAD therapy for ≥6 months with ≥75% reduction in symptomatic AF burden. Twenty-four patients (40%) had severe OSA. Thirty patients (49%) were rhythm controlled with AADs. Nonresponders to AADs were more likely to have severe OSA than milder disease (52% vs 23%, p <0.05); those with severe OSA were less likely to respond to AADs than participants with nonsevere OSA (39% vs 70%, p = 0.02). Nonresponders had higher apnea-hypopnea indexes than responders (34 ± 25 vs 22 ± 18 events/hour, p = 0.05), but there were no differences between these groups in minimum oxygen saturation or percentage of time spent in rapid eye movement sleep. In conclusion, patients with severe OSA are less likely to respond to AAD therapy for AF than those with milder forms of OSA.

Utility of digital pulse oximetry in the screening of lower extremity arterial disease

PurposeThe aim of this study was to evaluate screening methods in the lower extremities by measurement of the digital pulse oximetry (oxygen percent saturation [SpO2]) of toes for peripheral arterial disease (PAD).MethodsA prospective study was performed among 49 patients (98 limbs) with lower extremity arterial occlusive disease. We attempted to measure the ankle-brachial index (ABI), digital pulse oximetry (SpO2), and computerized tomographic angiography (CTA). Patients were divided into three groups by the traditional Fontaine classification system by symptom and CTA criteria: 1) Critical limb ischemia (Fontaine III and IV), 2) Claudication; (Fontaine II), and 3) asymptomatic limbs (Fontaine I).ResultsThe sensitivity, specificity, positive and negative predictive values between active treatment groups (group I and II; endovascular and open surgery) and conservative group (group III) are all statistically significant. ABI; 55.09%, 94%, 96.7%, 39.02% (R = 12.54, P < 0.000) SpO2; 87.06%, 87.8%, 84.3%, 90% (R = 40.11, P < 0.000). Pre-SpO2 and pre-ABI all show statistically significant correlation in group I vs. group II, symptomatic PAD (group I and II) vs. asymptomatic PAD (group III), and the total PAD comparison. The Pearson's correlation coefficient between SpO2 and ABI all show significant correlation in group II. Pre-SpO2 vs. Pre-ABI show strong positive correlation except asymptomatic group (group III).ConclusionDigital pulse oximetry can be a useful, simple, noninvasive screening device as well as ABI in PAD.