Apnea-induced hemoglobin desaturation during one-lung vs two-lung ventilation

Tomographic Comparison of Ventilation Techniques for CT-Guided Thoracoscopic Staple Excision of Subcentimeter Lung Nodules

This study was planned to compare the computed tomographic detectability of lung nodules in three ventilatory conditions: total lung capacity, high-frequency ventilation, and total lung deflation. In an ex vivo lung model, 44 nodules were simulated. Using computed tomography (CT) scans, nodules were detected and compared to the actual number and excised under CT guidance. Simulated nodules measured 6.2 +/- 2.1 mm and demonstrated an attenuation of 175 +/- 14 HU. Observer confidence was highest at total lung capacity (5.00 +/- 0.00), in comparison to high-frequency ventilation and total lung deflation (4.69 +/- 0.78, 4.94 +/- 0.27, p = .24). The kappa score for total lung capacity, high-frequency ventilation, and total lung deflation was 1.00, 0.96, and 0.98, respectively, indicating a very high interrater reliability. Although surgical devices generated a substantial artifact, 90% of nodules were excised. Thus, although total lung capacity produces the highest confidence level, all three of the ventilatory techniques examined have similar detection of subcentimeter pulmonary nodules using computed tomography scans.

Noninvasive bilevel positive airway pressure for preoxygenation of the critically ill morbidly obese patient

PURPOSE

We describe the use of noninvasive bilevel positive airway pressure (BiPAP) in a critically ill, hypoxemic and morbidly obese patient for preoxygenation prior to rapid sequence induction of anesthesia.

CLINICAL FEATURES

A critically ill morbidly obese patient (body mass index: 49 kg.m(-2)) was scheduled for urgent laparoscopic cholecystectomy. Preoxygenation with 5 L.min(-1) oxygen flow resulted in a moderate increase in oxygen saturation (SpO2) from 79% to 90%. Prior to rapid sequence induction of anesthesia, a trial of noninvasive BiPAP with oxygen delivery at 5 L.min(-1) increased his SpO2 to 95% initially, with full saturation of 99% achieved when oxygen flow was increased to 10 L.min(-1). Bilevel positive airway pressure with an inspiratory and expiratory pressures of 17 cm H2O and 7 cm H2O, respectively, was applied using a full face mask to achieve a tidal volume of 8 mL.kg(-1). Rapid sequence induction proceeded uneventfully.

CONCLUSIONS

Prior to rapid sequence induction of anesthesia in patients with respiratory compromise secondary to factors which reduce FRC, noninvasive BiPAP in combination with supplemental oxygen may be indicated whenever traditional preoxygenation does not provide adequate oxyhemoglobin saturation. Improved oxygenation is most likely attributable to improved ventilation and alveolar recruitment.

Approaches to hypoxemia during single-lung ventilation

Modern techniques to isolate the lungs, coupled with accurate continuous non-invasive monitoring, have made single-lung ventilation safe and easy to perform. Most patients maintain an adequate arterial oxygen tension during single-lung ventilation. In order to maximize oxygenation, efforts are directed towards optimizing perfusion and ventilation to the ventilated lung or increasing the oxygen content of blood returning from the collapsed lung.

Video-assisted thoracoscopy

Thoracoscopy is a minimally invasive operative endoscopic procedure designed for visual inspection of the thoracic cavity. The use of small, highly maneuverable, rigid telescopes allows visualization beyond what is possible by standard operative techniques. The use of a small video camera attached to a standard rigid telescope allows the operator and assistants to view a simultaneous, enlarged, and clear image. This article focuses on the basic diagnostic and surgical techniques used in veterinary video-assisted thoracoscopy.

Single vital capacity breath for preoxygenation

PURPOSE

The report investigates, in awake patients before induction of anesthesia, the effect of preoxygenation by the single vital capacity breath technique following forced exhalation on the mean arterial PO2 (PaO2).

METHODS

In 10 adult patients undergoing elective surgery, the mean PaO2 values achieved 30 sec after preoxygenation by the single vital capacity breath technique was compared with the mean PaO2 values achieved by preoxygenation by the traditional tidal volume breathing for three minutes. Each patient served as her/his own control.

RESULTS

The mean PaO2 following the single vital capacity breath technique was higher (295 +/- 67 mmHg) than that achieved by the traditional tidal volume breathing technique at 30 sec and 60 sec, and was not significantly different from that achieved by the traditional technique after three minutes (307 +/- 70 mmHg).

CONCLUSION

The single vital capacity breath technique following forced exhalation can rapidly provide adequate preoxygenation within 30 sec.