Accuracy and precision of buccal pulse oximetry

Objective

We sought to describe the accuracy and precision of buccal pulse oximetry (SbpO₂) compared with arterial oxygen saturation (SaO₂) and pulse oximetry (SpO₂) in healthy adults at normoxemia and under 3 induced hypoxemic conditions.

Methods

In this prospective, correlational study, SbpO₂, SaO₂, and SpO₂ values were recorded at normoxemia and at three hypoxemic conditions (SpO₂ = 90%, 80%, and 70%) for 53 healthy, nonsmoking adults who were without cardiac or pulmonary disease, baseline hypoxemia, peripheral edema, dyshemoglobinemia, and fever. Bland-Altman analyses were used to assess agreement and precision between SbpO₂ and SaO₂ measures and between SbpO₂ and SpO₂ measures. Data were adjusted to account for a lag time between buccal and finger sites.

Results

When comparing SbpO₂ and SaO₂ values, mean differences of -1.8%, .3%, 2.4%, and 2.6% were evident at the normoxemia, 90%, 80%, and 70% levels, respectively. When comparing SbpO₂ and SpO₂ values, the mean differences were -1.4%, .1%, 3.3%, and 4.7% at the normoxemia, 90%, 80%, and 70% levels, respectively. The SbpO₂ and SaO₂ values met a priori precision criteria (1.6%; 95% confidence limit, -4.9% to 1.3%) at normoxemia. The SbpO₂ and SpO₂ values met precision criteria at normoxemia (1.5%; 95% confidence limit, -4.4% to 1.5%) and 90% (1.9%; 95% confidence limit, -3.6% to 3.8%) conditions, but exceeded precision criteria at the other tested conditions. On average, SpO₂ lagged 21 seconds behind SbpO₂.

Conclusion

Buccal oximetry is an inaccurate and imprecise method of assessing SpO₂ when oxygen saturation is <90%. The divergence between SbpO₂ and both SaO₂ or SpO₂ values increased as hypoxemia worsened. The buccal method overestimated oxygen saturation in proportion to the degree of hypoxemia. Such overestimates may lead nurses to conclude falsely that a patient's arterial oxygen saturation is acceptable when further assessment or intervention is warranted.     

Adrenal insufficiency and response to corticosteroids in hypotensive critically ill children with cancer

Background

Assessment and treatment of adrenal axis function in critically ill pediatric patients with oncologic disorders have not been well elucidated. Critically ill children with oncologic disorders may be at increased risk for adrenal insufficiency (AI).

Objective

The aim of the present study was to evaluate the incidence of AI in a cohort of hypotensive patients with oncologic disorders and the correlation of AI with hemodynamic response to corticosteroids.

Design/Methods

This is a retrospective review of pediatric oncology patients with systemic inflammatory response syndrome and vasopressor-dependent shock receiving protocol-based adrenocorticotropin testing and steroid supplementation. Vasopressor dose requirements were evaluated before and after the initiation of corticosteroids. Absolute AI (AAI) was defined as baseline cortisol less than 18 μg/dL. Relative AI (RAI) was defined as δ-cortisol less than 9 μg/dL.

Results

Twenty patients received adrenocorticotropin testing; primary diagnoses were 13 hematologic malignancies and 7 solid tumors. The median age was 132 months (range, 4-224 months). The median fluid resuscitation was 80 mL/kg (range, 60-120 mL/kg), with 10 (50%) of 20 patients requiring mechanical ventilation for a median of 12 days. Overall, 10 (50%) of 20 patients met the definition for RAI, 15 (75%) of 20 met the definition for AAI, and 18 (90%) of 20 had either AAI or RAI. All patients received steroids: 18 (90%) of 20 on dopamine and 17 (85%) of 20 on norepinephrine. After the introduction of steroids, dosage of norepinephrine and dopamine was significantly reduced in 4 hours (P = .0001).

Conclusions

Both RAI and AAI were common in this cohort of critically ill pediatric patients with oncologic disorders. Introduction of steroids was associated with a significant reduction in vasopressors dose.     

Correlation of patient-reported outcomes of sedation and sedation assessment scores in critically ill patients

Purpose

Patient-reported outcomes (PROs) are recommended as indicators of quality in the intensive care unit. We studied the correlation between PROs of sedation quality and a universal sedation assessment scale in critically ill patients.

Materials and methods

Twenty-nine mechanically ventilated adults admitted to a surgical/trauma or medical intensive care unit requiring continuous infusion sedation for 24 hours or more were prospectively included. Patient-reported outcomes were evaluated through sedation questionnaire 24 hours post–continuous infusion sedation. The primary outcome was the correlation of PROs with Sedation-Agitation Scale (SAS) scores.

Results

Mean (SD) SAS scores per 12-hour nursing shift for propofol (n = 179), midazolam (n = 42), and dexmedetomidine (n = 8) were 3.78 (77), 3.31 (1.1), and 2.98 (0.76), respectively. The mean score for survey questions addressing perceptions of comfort was 5.3 (1, complete comfort; 10, not comfortable at all). Of the patients, 34%, 7%, and 52% would want more, less, or the same amount of sedation, respectively, if this situation were to arise again. Patient perception of comfort correlated with the percent time at goal SAS score; r = 0.31 (P < .05).

Conclusion

Patient-reported outcomes of sedation correlate with the percentage of time spent in the goal range of scores for a universal sedation assessment scale. These findings represent initial attempts to appreciate the patient's perspective in the management and monitoring of agitation.     

Lack of caspase‐3 attenuates immobilization‐induced muscle atrophy and loss of tension generation along with mitigation of apoptosis and inflammation

Introduction: Immobilization by casting induces disuse muscle atrophy (DMA). Methods: Using wild type (WT) and caspase‐3 knockout (KO) mice, we evaluated the effect of caspase‐3 on muscle mass, apoptosis, and inflammation during DMA. Results: Caspase‐3 deficiency significantly attenuated muscle mass decrease [gastrocnemius: 28 ± 1% in KO vs. 41 ± 3% in WT; soleus: 47 ± 2% in KO vs. 56 ± 2% in WT; (P < 0.05)] and gastrocnemius twitch tension decrease (23 ± 4% in KO vs. 36 ± 3% in WT, P < 0.05) at day 14 in immobilized vs. contralateral hindlimb. Lack of caspase‐3 decreased immobilization‐induced increased apoptotic myonuclei (3.2‐fold) and macrophage infiltration (2.2‐fold) in soleus muscle and attenuated increased monocyte chemoattractant protein‐1 mRNA expression (2‐fold in KO vs. 18‐fold in WT) in gastrocnemius. Conclusions: Caspase‐3 plays a key role in DMA and associated decreased tension, presumably by acting on the apoptosis and inflammation pathways. Muscle Nerve 47: 711–721, 2013