Henrik Reinius

Prevention of atelectasis in morbidly obese patients during general anesthesia and paralysis : a computerized tomography study

Background:Morbidly obese patients show impaired pulmonary function during anesthesia and paralysis, partly due to formation of atelectasis. This study analyzed the effect of general anesthesia and three different ventilatory strategies to reduce the amount of atelectasis and improve respiratory function. Methods:Thirty patients (body mass index 45 ± 4 kg/m2) scheduled for gastric bypass surgery were prospectively randomized into three groups: (1) positive end-expiratory pressure of 10 cm H2O (PEEP), (2) a recruitment maneuver with 55 cm H2O for 10 s followed by zero end-expiratory pressure, (3) a recruitment maneuver followed by PEEP. Transverse lung computerized tomography scans and blood gas analysis were recorded: awake, 5 min after induction of anesthesia and paralysis at zero end-expiratory pressure, and 5 min and 20 min after intervention. In addition, spiral computerized tomography scans were performed at two occasions in 23 of the patients. Results:After induction of anesthesia, atelectasis increased from 1 ± 0.5% to 11 ± 6% of total lung volume (P < 0.0001). End-expiratory lung volume decreased from 1,387 ± 581 ml to 697 ± 157 ml (P = 0.0014). A recruitment maneuver + PEEP reduced atelectasis to 3 ± 4% (P = 0.0002), increased end-expiratory lung volume and increased Pao2/Fio2 from 266 ± 70 mmHg to 412 ± 99 mmHg (P < 0.0001). PEEP alone did not reduce the amount of atelectasis or improve oxygenation. A recruitment maneuver + zero end-expiratory pressure had a transient positive effect on respiratory function. All values are presented as mean ± SD. Conclusions:A recruitment maneuver followed by PEEP reduced atelectasis and improved oxygenation in morbidly obese patients, whereas PEEP or a recruitment maneuver alone did not.

Real‐time ventilation and perfusion distributions by electrical impedance tomography during one‐lung ventilation with capnothorax

Carbon dioxide insufflation into the pleural cavity, capnothorax, with one‐lung ventilation (OLV) may entail respiratory and hemodynamic impairments. We investigated the online physiological effects of OLV/capnothorax by electrical impedance tomography (EIT) in a porcine model mimicking the clinical setting.

Outbreak of enterovirus D68 of the new B3 lineage in Stockholm, Sweden, August to September 2016

We report an enterovirus D68 (EV-D68) outbreak in Stockholm Sweden in 2016. Between 22 August and 25 September EV-D68 was detected in 74/495 respiratory samples analysed at the Karolinska University Hospital. During the peak week, 30/91 (33%) samples were EV-D68 positive. Viral protein (VP)P4/VP2 sequencing revealed that cases were caused by B3 lineage strains. Forty-four (59%) EV-D68-positive patients were children aged ≤ 5 years. Ten patients had severe respiratory or neurological symptoms and one died.

Physiological changes associated with routine nursing procedures in critically ill are common: an observational pilot study

Nursing procedures that are routinely performed in the intensive care unit (ICU) are assumed to have minimal side effects. However, these procedures may sometimes cause physiological changes that negatively affect the patient. We hypothesized that physiological changes associated with routine nursing procedures in the ICU are common.

Severe diabetic ketoacidosis in combination with starvation and anorexia nervosa at onset of type 1 diabetes : A case report

Abstract We here report a case of diabetic ketoacidosis at onset of type 1 diabetes after a prolonged period of starvation due to anorexia nervosa. A 53-year-old female with a history of anorexia nervosa was admitted to the psychiatric clinic due to psychotic behaviour and inability to take care of herself. Twenty-four hours after admission she was transferred to the clinic of internal medicine due to altered mental status, and laboratory screening revealed a pH of 6.895 and blood glucose concentration of 40 mmol/L. Due to the unusual combination of prolonged starvation and diabetic ketoacidosis we implemented some modifications of existing treatment guidelines and some special considerations regarding nutrition in order to prevent a re-feeding syndrome.

Maintenance of Airway Pressure During Filter Exchange Due to Auto-Triggering

BACKGROUND: Daily routine ventilator-filter exchange interrupts the integrity of the ventilator circuit. We hypothesized that this might reduce positive airway pressure in mechanically ventilated ICU patients, inducing alveolar collapse and causing impaired oxygenation and compliance of the respiratory system. METHODS: We studied 40 consecutive ICU subjects (PaO2/FIO2 ratio ≤ 300 mm Hg), mechanically ventilated with pressure-regulated volume control or pressure support and PEEP ≥ 5 cm H2O. Before the filter exchange, (baseline) tidal volume, breathing frequency, end-inspiratory plateau pressure, and PEEP were recorded. Compliance of the respiratory system was calculated; FIO2, blood pressure, and pulse rate were registered; and PaO2, PaCO2, pH, and base excess were measured. Measurements were repeated 15 and 60 min after the filter exchange. In addition, a bench test was performed with a precision test lung with similar compliance and resistance as in the clinical study. RESULTS: The exchange of the filter took 3.5 ± 1.2 s (mean ± SD). There was no significant change in PaO2 (89 ± 16 mm Hg at baseline vs 86 ± 16 mm Hg at 15 min and 88 ± 18 mm Hg at 60 min, P = .24) or in compliance of the respiratory system (41 ± 11 mL/cm H2O at baseline vs 40 ± 12 mL/cm H2O at 15 min and 40 ± 12 mL/cm H2O at 60 min, P = .32). The bench study showed that auto-triggering by the ventilator when disconnecting from the expiratory circuit kept the tracheal pressure above PEEP for at least 3 s with pressure controlled ventilation. CONCLUSIONS: This study showed that a short disconnection of the expiratory ventilator circuit from the ventilator during filter exchange was not associated with any significant deterioration in lung function 15 and 60 min later. This result may be explained by auto-triggering of the ventilator with high inspiratory flows during the filter exchange, maintaining airway pressure. (ISRCTN.org registration ISRCTN76631800.)

Optimal PEEP during one lung ventilation with capnothorax. An experimental study

One‐lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions.

Is Protective Lung Ventilation Safe in Morbidly Obese Patients

Mechanical ventilation during general anesthesia is mandatory to maintain physiologic gas-exchange. However, recent evidence suggests that mechanical ventilation might also promote ventilator induced lung injury. During general anesthesia obese patients are characterized by a marked reduction in end-expiratory lung volume (70% compared to awake) and increased atelectasis (20–30% of the lung parenchyma). These changes are associated with a reduction in respiratory system compliance and tidal airway closure, which can occur when the closing volume exceeds the end-expiratory lung volume. The opening and closing of atelectatic lung regions as well as collapsed peripheral airways might induce ventilator induced lung injury, with or without major inflammatory response. Experimental studies, as well as retrospective and prospective clinical studies suggest that the use of large tidal volume (Vt) favors the development of lung injury. Side effects associated with the use of lower Vt, like permissive hypercapnia, seem to be minimal. On the other hand, application of moderate positive end-expiratory pressure (PEEP) levels between 5 and 15 cm H2O may decrease airway closure and/or keep open the lung parenchyma, avoiding the ventilator induced lung injury. Before application of PEEP, to effectively reopen atelectatic areas, a recruitment maneuver (RM) at 35–40 cm H2O of plateau pressure, for at least 5 s should be performed. The clinical effectiveness of this ventilatory approach to prevent postoperative pulmonary complications must be investigated in prospective randomized studies. During general anesthesia in morbidly obese patients we recommend the following: (a) Vt reduction to 6–8 ml/kg of ideal body weight, increasing respiratory rate to maintain physiological PaCO2, while avoiding excessive auto-PEEP, (b) PEEP set between 5 and 15 cm H2O, (c) application of a RM before PEEP, and (d) monitoring of auto-PEEP and airway inspiratory pressures.