Jutta Novalija

The Effectiveness of Oxygen Delivery and Reliability of Carbon Dioxide Waveforms: A Crossover Comparison of 4 Nasal Cannulae

BACKGROUND:Effective O2 delivery and accurate end-tidal CO2 (ETCO2) sampling are essential features of nasal cannulae (NCs) in patients with compromised respiratory status. We studied 4 NC designs: bifurcated nasal prongs (NPs) with O2 delivery and CO2 sensing in both NPs (Hudson), separate O2/CO2 NPs (Salter), and CO2 sensing in NPs with cloud O2 delivery outside the NPs via multi vents (Oridion) and dual vents (Medline). We hypothesized that design differences between NCs would influence O2 delivery and ETCO2 detection. METHODS:Forty-five healthy volunteers, 18 to 35 years, participated in an unrestricted, randomized block design, each subject serving as their own control in a 4-period crossover study design of 4 NCs during one session. Monitoring included electrocardiogram, posterior pharynx O2 sampling from a Hauge Airway (Sharn Anesthesia Products, Tampa, FL), and NC ETCO2. In 11 volunteers, radial artery blood was sampled from a catheter for partial pressures of O2 and carbon dioxide (PaO2 and PaCO2) determination. Per randomization, each NC was positioned, and data were collected over 2 minutes (ETCO2, pharyngeal O2, PaO2, and PaCO2) during room air and during O2 fresh gas flows (FGFs) of 2, 4, and 6 Lpm. Statistical analyses were performed with SAS Analytics Pro, Version 9.3, and JMP Statistical Software, Version 11 (SAS Institute Inc., Cary, NC), significance at P < 0.05. RESULTS:Blood gas analyses indicated PaCO2 during steady state at each experimental time period remained unchanged from physiologic baseline. PaO2 did not differ between NC devices at baseline or 2 Lpm O2. The PaO2 at 4 Lpm from the separate NPs and bifurcated NCs was significantly higher than the multi-vented NC. Pharyngeal O2 with the NC with separate NPs was significantly higher than multivented and dual-vented cloud delivery NCs at 2, 4, and 6 Lpm FGF. Pharyngeal O2 with the NC with bifurcated NPs was significantly higher than the multi-vented NC at 2 Lpm, and higher than cloud delivery NCs at 4 and 6 Lpm FGF. ETCO2 was significantly lower with the NC with bifurcated NPs compared to the other 3 NCs, consistent with errant CO2 tracings at higher FGF. CONCLUSIONS:NCs provide supplemental inspired O2 concentrations for patients with impaired pulmonary function. Accurate measures of ETCO2 are helpful in assessing respiratory rate and determining whether CO2 retention is occurring from hypoventilation. These findings suggest the NC with separate NPs was the most effective in delivering O2 and the most consistent at providing reliable CO2 waveforms at higher FGFs.

Malignant Hyperthermia Crisis: Optimizing Patient Outcomes Through Simulation and Interdisciplinary Collaboration

Malignant hyperthermia (MH) is a rare, life-threatening event. Many clinicians are unprepared to manage an MH crisis in the perioperative setting because it requires the use of low-frequency, high-risk skills and procedures. Simulation is a recognized educational method for cumulative and integrative learning in a safe environment that resembles real-life clinical scenarios. The aim of this quality improvement project was to provide simulation-based learning to perioperative personnel to educate them in the early recognition, treatment, and management of MH. An interdisciplinary team developed an MH education plan. Implementation of the plan involved a two-part training: an educational session, and a role-playing scenario using high-fidelity OR simulation. Simulation teaching provided OR personnel with an opportunity for skill development, teamwork, interdisciplinary communication, and problem solving. Personnel responded favorably and identified positive outcomes, such as role clarity, improved anticipatory response, and overall team cohesion. In addition, the project included updating the MH cart and writing the hospitals MH policy.

Intracardiac Masses Associated With Permanent Endocardial Pacemaker Lead Erosion Through the Skin

72-YEAR-OLD, 178-cm, 57-kg man presented to the authors’ institution with an exposed permanent endocardial pacemaker lead adjacent to an old left subclavian pacing generator pocket. The patient reported that a “cystic” swelling began over the old generator site approximately 4 months before admission. The pacemaker lead eroded through the skin 2 months later, but the patient had only recently sought medical attention for an unrelated problem. He denied fevers, chills, or drainage at the wire-erosion site. The patient had a 16-year history of complete heart block. A left subclavian dual-chamber pacemaker placed shortly after his initial diagnosis had func

Morbid Obesity and Obstructive Sleep Apnea: The Challenging Link

Obstructive sleep apnea (OSA) is a common medical condition that is increasing in prevalence and is associ- ated with substantial morbidity and a 40% eight-year mortality rate if left untreated. Morbidly obese patients have a greater incidence of co-morbid disease, including OSA. OSA is characterized by repeated upper airway obstruction and arousal during sleep, sympathetic activation, hypertension and daytime somnolence. In morbidly obese OSA patients undergoing surgical procedures, the perioperative period is more challenging than in non obese OSA patients. Their airway anatomy is often abnormal with excess pharyngeal tissue and tongue size making it difficult to ventilate thru a facemask and to establish tracheal intubation. Several suggestions for optimizing the anesthetic induction, emergence, and early recovery periods in these patients are offered. Most important are positioning of the patient (both during and post surgery), pre-oxygenation prior to intubation, proper dosing of anesthetic maintenance drugs to ideal body weight, alveolar recruitment maneuvers, full reversal of paralysis at the end of surgery, and careful drug titration in recovery to improve pulmonary mechanics. With proper preparation and precautions it is possible to avoid the significant high frequency of respiratory and cardiac complications observed in these patients and to avoid or better manage length of hospital stay, unplanned ICU admission and/or reintubation.

Gradual Development of Unilateral Horner's Syndrome in an Otherwise Asymptomatic Elderly Man

m 64-YEAR-OLD, 88-kg, 185-cm man presented to the authors’ institution with a history of slowly progressive rightye ptosis and miosis of 18 months duration. The patient reported nhydrosis of the right side of his face. He denied a history of fever r chills, fatigue, weight loss, hoarseness or other changes in his oice, chest pain, pulmonary symptoms, or tobacco abuse. The hysical examination confirmed the presence of right-eye ptosis nd miosis consistent with unilateral Horner’s syndrome. Anisooria was present (left right), but both pupils constricted approriately in response to light. Motor function of the right eye was ully intact. An ophthalmologic examination revealed no intraoclar abnormalities. No masses or adenopathy were palpable in the eck nor were other focal motor or sensory deficits observed uring neurologic examination of the head and neck. Auscultation

Anesthesia Preoperative Clinic Evaluation of Obstructive Sleep Apnea Using Nasal Fiberoptic Videoendoscopy: A Pilot Study Comparison with Polysomnography

Background Nasal fiberoptic videoendoscopy is an established technique to assess upper airway pathology in conscious and sedated patients. Objectives The authors conducted a prospective proof-of-concept pilot study to evaluate whether airway narrowing detected using nasal fiberoptic videoendoscopy in the anesthesia preoperative clinic was capable of defining the severity of obstructive sleep apnea (OSA) in patients scheduled for elective surgery. Methods After application of topical local anesthesia (4% lidocaine with phenylephrine), sixteen patients (ASA physical status 2 or 3) underwent nasal fiberoptic videoendoscopy in sitting position. The magnitudes of retropalatal and retrolingual luminal narrowing were assessed as predictors of OSA. Patients also underwent polysomnography and completed STOP-Bang questionnaires. The endoscopist’s clinical impression of OSA severity based on the history and airway examination was quantified. Results Retropalatal luminal narrowing and STOP-Bang score ≥ 4 predicted OSA severity as either “none or mild” or “moderate to severe” in 13 (81%) and 9 (56%) of 16 patients who underwent polysomnography, respectively. OSA severity was significantly (Spearman’s rank correlation coefficient) associated with retropalatal airway narrowing (P = 0.0048), STOP-BANG score (P = 0.0072), and body mass index (P = 0.0091), whereas clinical impression and retrolingual pharyngeal narrowing were not (P=0.093 and P = 0.11, respectively). Conclusions The current results suggest that nasal fiberoptic videoendoscopy quantification of retropalatal airway narrowing may be a useful tool for assessing the severity of OSA in the anesthesia preoperative clinic. The current findings document a proof-of-concept feasibility of nasal fiberoptic videoendoscopy as a screening tool for OSA in conscious patients during preoperative evaluation that may justify further prospective clinical trials of this technique.

Moderate, Short-Term, Local Hyperglycemia Attenuates Forearm Endothelium-Dependent Vasodilation After Transient Ischemia-Reperfusion in Human Volunteers

OBJECTIVE Acute hyperglycemia causes endothelial dysfunction in diabetic patients, abolishes ischemic pre- and postconditioning, and is an independent predictor of adverse outcome after myocardial infarction in nondiabetic patients. Its effects on endothelial-dependent vasodilation are controversial in healthy subjects. The authors studied the effect of moderate short-term local hyperglycemia on forearm endothelium-dependent vasodilation in healthy volunteers. DESIGN Randomized, crossover, blinded, 2-visit, pilot design. SETTING Veterans Affairs Medical Center. PARTICIPANTS Five male and 3 female healthy adult volunteers (23±4 years; height 171±13 cm; weight 66±9 kg; [mean±standard error of the mean]). INTERVENTIONS At each visit, volunteers received an infusion through a brachial artery catheter of either 0.9% saline or dextrose in the experimental, non-dominant arm, to establish mild forearm hyperglycemia. Hemodynamics and forearm blood flow (FBF; plethysmography) were measured at baseline, during brachial artery infusions of acetylcholine in consecutive increments (5, 10, and 15 μg/min), before ischemia (20 min, blood pressure cuff at 200 mmHg), and after 15 minutes of reperfusion. Blood glucose and insulin concentrations were determined from venous samples. The effect of duration of intra-arterial dextrose on FBF was examined. MEASUREMENTS AND MAIN RESULTS Dextrose increased steady-state blood glucose concentration in the experimental but not the control arm (dominant arm). Dextrose increased FBF compared with saline (4.5±0.5 v 2.6±0.4 mL/min/100 g of tissue, respectively). Acetylcholine caused similar increases in FBF in the absence and presence of dextrose (+239±90% v+203±75%, respectively, during 15 μg/min). The duration of dextrose did not affect this acetylcholine-induced vasodilation. Acetylcholine-stimulated increases in FBF were attenuated in dextrose-treated versus saline after reperfusion (+180±18% v+257±53%, respectively, during 10 μg/min). Interventions in the experimental arm did not affect FBF in the control arm. CONCLUSION These results indicated that moderate, short-term, local hyperglycemia induced by intra-arterial administration of dextrose attenuated forearm endothelial-dependent vasodilation after ischemia-reperfusion injury in healthy volunteers.

Short-Term Angiotensin Subtype 1 Receptor Blockade Does Not Alter the Circulatory Responses to Sympathetic Nervous System Modulation in Healthy Volunteers Before and During Sevoflurane Anesthesia: Results of a Pilot Study

OBJECTIVE The mechanism of perioperative hypotension in patients taking an angiotensin-receptor blocker up to the time of surgery remains unclear. This study tested the hypothesis that short-term angiotensin-receptor blocker treatment attenuated the sympathetic and vascular responses to autonomic stimuli in volunteers undergoing anesthesia. DESIGN Randomized, crossover, blinded, pilot design. SETTING Zablocki Veterans Affairs Medical Center, Milwaukee, WI. PARTICIPANTS The study comprised 8 male and 6 female healthy, young volunteers (age 23±1.2 years [mean±standard error of the mean]). INTERVENTIONS Volunteers were studied after receiving oral placebo or 50 mg of losartan (angiotensin-receptor blocker) for 3 days before each test day. The effectiveness of angiotensin-receptor blocker treatment was confirmed using the mean arterial blood pressure response to intravenous angiotensin II (1-µg bolus). Eight volunteers underwent direct mean arterial pressure and forearm bloodflow measurements during conscious baseline, a cold pressor test, induction of anesthesia, tracheal intubation, maintenance of anesthesia with 1 minimum alveolar concentration of sevoflurane, and airway irritation with 12% desflurane. Six volunteers experienced mean arterial pressure responses to 0.1 mg of phenylephrine at baseline and during 1 minimum alveolar concentration of sevoflurane. MEASUREMENTS AND MAIN RESULTS Comparisons were made over time and across groups. Angiotensin-receptor blocker treatment significantly reduced-mean arterial pressure and forearm vascular resistance (forearm blood flow/mean arterial pressure) over time and blocked the mean arterial pressure response to angiotensin-II challenge. The changes in mean arterial pressure and forearm vascular resistance in response to all stressors did not differ between treatments. Mean arterial pressure increases from phenylephrine were preserved. CONCLUSIONS In healthy, young volunteers, sympathetically-mediated responses from the short-term use of an angiotensin-receptor blocker were not altered and most likely did not contribute to perioperative hypotension during the intraoperative period.

An unlikely cause of a new diastolic murmur heard during a routine employment physical exam.

A44-YEAR-OLD, 117-kg, 188-cm previously healthy man was referred to the authors’ institution for evaluation of a new diastolic murmur that was heard during a routine employment physical examination. The patient incidentally reported a 3-month history of occasional dyspnea and dizziness, but these symptoms were not particularly concerning to him nor did they cause him to seek medical attention, limit his weightlifting

Mechanism of Torrential Regurgitation in Mitral Valve Endocarditis: The Usual Chordal Rupture-Leaflet Flail or Another More Dramatic Structural Defect?

Fig 3. Midesophageal 4-chamber TEE color Doppler image showing severe mitral regurgitation through the anterior mitral leaflet perforation. A CACHETIC 72-YEAR-OLD, 63-kg, 180-cm man with essential hypertension, chronic obstructive pulmonary disease, chronic anemia, a recent cerebral vascular accident, alcohol abuse, and malnutrition was transferred to the authors’ institution from a rural Veterans Affairs Medical Center for definitive treatment of acute mitral valve endocarditis complicated by sepsis. Blood cultures obtained at the outside hospital were positive for methicillin-sensitive Staphylococcus Aureus. Long-term organismspecific intravenous antibiotic therapy was begun based on culture sensitivities. An initial transesophageal echocardiography (TEE) examination demonstrated a 1.5 1.2 cm vegetation on the anterior mitral valve leaflet, severe mitral regurgitation resulting from chordal rupture-A2 segment flail and pulmonary hypertension (estimated pulmonary arterial systolic pressure of 51 mmHg by continuous-wave Doppler of tricuspid valve regurgitant jet velocity). Persistent fever, systemic hypotension treated with vasoactive medications, and respiratory failure requiring positive-pressure ventilation complicated the patient’s course before and after his transfer to the authors’ hospital. Multiple foci of septic embolization, including L5-S1 osteomyelitis-discitis, an adjacent small epidural abscess without neurologic sequelae, left ileopsoas polymyositis, left hip septic arthritis, and several embolic brain infarcts also were present when the patient was admitted. Surgical drainage of the septic hip and continuation of intravenous antibiotic therapy combined with total parenteral nutrition stabilized the patient’s hemodynamic status, normalized his temperature, eliminated the bacteremia, and reduced his elevated white blood cell count toward normal values. Nevertheless, the patient could not be weaned from mechanical ventilation, presumably because of severe mitral regurgitation. Indeed, a second TEE study performed in the authors’ echocardiography laboratory confirmed the original findings. Because the patient’s overall clinical picture had improved substantially, he was taken to the operating room for mitral valve replacement after coronary angiography documented the absence of hemodynamically significant coronary artery stenoses. An intraoperative TEE examination was performed after anesthetic induction and