Speed of collapse of the non-ventilated lung during one-lung anaesthesia: the effects of the use of nitrous oxide in sheep.

By enhancing gaseous uptake from the non-ventilated lung during procedures performed thoracoscopically, the rapid diffusion properties of nitrous oxide would be expected to speed lung collapse and so facilitate surgery. To assess the effect of nitrous oxide on the speed of absorptive lung collapse, a study was conducted using 11 anaesthetised sheep. Speed of collapse was assessed in an indirect manner by recording the time required in a closed-chest situation for the airway pressure distal to a single lung airway occlusion to decrease to - 1.0 kPa. The influence of nitrous oxide was assessed by comparing the time taken for this decrease in airway pressure when the animal was being mechanically ventilated with 50% nitrous oxide in oxygen with the time taken when using 100% oxygen. In all assessments, it was found that the decrease in airway pressure to - 1.0 kPa occurred in a shorter time when nitrous oxide was used. The findings lend support to the hypothesis that during thoracoscopic surgery, mechanical lung ventilation with an oxygen/nitrous oxide mixture will increase the rate of gaseous uptake from the non-ventilated lung and so hasten its absorptive collapse.

Speed of collapse of the non-ventilated lung during single-lung ventilation for thoracoscopic surgery: the effect of transient increases in pleural pressure on the venting of gas from the non-ventilated lung.

A study of 10 anaesthetised patients placed in the lateral position for thoracoscopic surgery assessed whether transient increases in pleural pressure on the side of the non-ventilated lung might increase the speed at which gas vents from that lung. The transient increases in pleural pressure were generated by the mediastinal displacement that occurs with each inspiratory phase of positive pressure ventilation of the dependent lung. When combined with a unidirectional valve allowing gas to flow out of the non-ventilated lung, and a second valve allowing ambient airflow into, but not out of, the thoracic cavity via an initial thoracoscopy access site, this mediastinal displacement could conceivably serve to 'pump' gas out of the non-ventilated lung. Using the four different combinations of valve inclusion or omission, the volume of gas that vented from the non-ventilated lung into a measuring spirometer was recorded during a 120-s measurement sequence. It was found that the speed of venting was not increased by the transient increases in pleural pressure, and that in all but one of a total of 34 measurement sequences, venting had ceased by the end of the sequence. Gas venting was a mean (SD) of 85.5 (11.9)% complete in 25 s (five breaths), and 96.6 (6.1)% complete in 60 s. This prompt partial lung collapse very likely reflected the passive elastic recoil of the lung, while the failure of transient increases in pleural pressure to result in ongoing venting of gas was probably a consequence of airways closure as the lung collapsed. It is concluded that techniques that aim to speed lung collapse by increasing pleural pressure are unlikely to be effective.

Lung volume reduction surgery in emphysema: a systematic review.

The aim of this study was to systematically review the literature regarding the safety and efficacy of lung volume reduction surgery (LVRS) in patients with emphysema. Studies on LVRS to August 2000 were identified using MEDLINE, Embase, Current Contents, and the Cochrane Library. Human studies of patients with upper, lower or diffuse distributions of emphysema were included. All types of bullous emphysema were excluded. A surgeon and researcher independently assessed the retrieved articles for their inclusion in the review. When LVRS was compared with medical management, at 2 years LVRS was associated with a higher FEV1 and at least equivalent survival. The use of staple excision of selected areas of lung appeared to be more efficacious than laser ablation. There is insufficient evidence to show preference for median sternotomy or videoscopically assisted thoracotomy, as the more safe and efficacious procedure. In highly selected patients with emphysema LVRS is deemed an acceptable treatment. To fully evaluate the safety and efficacy of LVRS, outcomes beyond 2 years must be included. The results of prospective randomized trials between medical management and LVRS, now in progress, are essential before a final assessment can be made.

Lobectomy for cavitating lung abscess with haemoptysis: strategy for protecting the contralateral lung and also the non-involved lobe of the ipsilateral lung.

We describe the anaesthetic management of a patient undergoing lobectomy for cavitating lung abscess complicated by haemoptysis. Surgery for lung abscess is one of the absolute indications for the use of a double-lumen tube (DLT). Because pus or blood could impede fibreoptic-assisted DLT placement, a traditional, blind placement of the DLT was performed. To protect the uninvolved parts of the operated lung, ventilation of the lung with the abscess was not performed until the resection of the involved lobe had been completed.

The long-term results of cartilage removal alone for the treatment of chondrodermatitis nodularis.

Cartilage excision alone has been demonstrated to be an effective technique in the treatment of chondrodermatitis nodularis (CDN), and in the short term is associated with an 80% cure rate. The objective of this study was to demonstrate that long-term disease control could be achieved using this surgical technique. Set in three hospital dermatology departments, 94 patients with CDN affecting the helix and antihelix were contacted by postal questionnaire at least 6 months after surgery. Replies were received from 77; 11 patients had died and six could not be traced. The main outcome measure was the identification of those patients in remission and those with disease recurrence. Sixty-two helix lesions were followed up for a mean of 52 months (range 8-99). There was recurrence in 10 patients (all men; 16%). Twenty antihelix lesions were followed up for a mean of 55 months (range 8-93). There was recurrence in five patients (all women; 25%). In conclusion, this study confirms that only cartilage needs to be excised for the long-term effective treatment of CDN. The only relevant aetiological factor identified was that all except one patient slept on the same side as the CDN. We believe that pressure on the ear during sleep causes CDN. This is most evident on the most protuberant part of the ear.

Gas movement in the nonventilated lung at the onset of single-lung ventilation for video-assisted thoracoscopy.

To assess the potential for atmospheric nitrogen to enter the nonventilated lung following the initiation of single-lung ventilation, the nonventilated lung of 10 patients undergoing video-assisted thoracoscopy was connected to the air in a water-filled spirometer, and gas movement out of and back into the lung was measured. Airway pressure from both lungs and pleural pressure from the nonventilated side were also measured. With each breath of positive-pressure ventilation to the ventilated lung prior to the thoracic cavity being opened to the atmosphere, the pressure transmitted to the opposite hemithorax generated a mean (range) tidal movement of gas in the nonventilated lung of 134 (65-265) ml. In addition, ongoing gas exchange resulted in a progressive influx of gas from the spirometer over the 110-120 s measurement period of a mean (range) volume of 155 (70-320) ml. This easily preventable influx of atmospheric nitrogen could, in theory, predispose to arterial desaturation and to delayed lung collapse after the parietal pleura is opened.

Ambient pressure oxygen reservoir apparatus for use during one-lung anaesthesia.

An ambient pressure oxygen reservoir bag apparatus for connecting to the nonventilated lung as soon as single-lung ventilation is initiated is described. The theoretical benefits are the facilitation of collapse of the lung on the side of surgery and a reduced likelihood of arterial desaturation. Although these main benefits are yet to be proven, the authors believe that the weight of theoretical argument and practical observation serves to justify the use of the apparatus while the outcome of suitably designed clinical trials is awaited. It can be used for all one-lung anaesthetics and is especially recommended for thoracoscopic surgery, where temporary re-expansion of the nonventilated lung is either counter-productive or contraindicated, and where there is a possibility that lung collapse may be delayed.

Systemic lupus erythematosus complicating complement type 2 deficiency: successful treatment with fresh frozen plasma.

We report a man who presented in 1981 at the age of 30 with cutaneous lupus erythematosus (LE), which was resistant to a range of treatments over the subsequent 11 years. In 1991 he suffered fits, dysphasia and agitated depression, and in 1992 a severe septicaemic illness. Systemic LE was diagnosed, and investigation showed homozygous complement type 2 deficiency (C2d). Over a period of 30 months he has received 6 weekly fresh frozen plasma. Since starting this treatment his cutaneous disease has resolved and his depression, verbal fluency and psychomotor scores improved. We have not observed any adverse effects to this treatment and suggest it should be considered in similar patients.

Shave excision of benign papular naevocytic naevi.

Patients frequently request removal of benign papular naevi for cosmetic or functional reasons. Shave excision plus electrocautery is probably the most widely used method of removal, but this method is said to result in retained hair or pigment if deeply pigmented or hairy naevi are treated. In a prospective study, 82 benign papular naevi of all types were treated by shave excision using hot-wire electrocautery for haemostasis. Details of the naevi were accurately recorded before treatment and reassessment of shave sites carried out at 6-8 months. At review, a scar was visible at only 63% (52/82) of shave sites and all of these were cosmetically acceptable. Only 27% (15/55) of the initially pigmented naevi retained pigment and only 24% (5/21) of the initially hairy naevi regrew hair. Shave excision and electrocautery of benign naevi, including hairy and deeply pigmented ones, produce excellent cosmetic results. The patient must be warned that there is a potential risk of a scar or pigment remaining after shave excision of any naevus and for hair regrowth after shave excision of hairy naevi.

Relation between size of skin excision, wound, and specimen.

BACKGROUND: Skin wounds differ in shape and size compared with the planned excision, and skin shrinks after excision and fixation. OBJECTIVE: This study was designed to quantify and to analyze the differences between the size and shape of the planned excision, wound, and specimen. METHODS: Eighty-six patients with 93 benign or malignant skin tumors were prospectively studied. Length and width measurements were made of the lesion, planned surgical excision, postexcision wound, and prefixation and postfixation specimens. The results were analyzed to identify the effects of patient age and sex, and lesion type and site. RESULTS: Wound size was larger than planned excision size in 90% of wounds, and this effect was greatest in young patients and at trunk and limb sites. Excision and fixation caused the specimens to shrink so that the postfixation area was on average 48% of the planned excision area; benign tumors shrank more than malignant tumors. CONCLUSION: Significant differences among planned excision, wound, and specimen sizes are influenced by patient age and by lesion site and type. These results demonstrate that wound size is not equivalent to tumor size, a conclusion often made in Mohs surgery. Furthermore, assessment of tumor clearance margins from fixed tissue does not reflect in vivo clearance margins.

Comparison of wound closure by means of dog ear repair and elliptical excision.

BACKGROUND: Elliptical excision is a standard method of skin tumor removal. The technique commits the operator to the direction and length of wound closure before lesion excision and hence before the shape and size of the resulting defect is known. OBJECTIVE: This study was designed to compare the predicted results of elliptical excision with those achieved after tumor excision and dog ear repair. METHODS: Fifty-one patients with benign and malignant skin tumors were prospectively studied. Each lesion was examined and an optimal ellipse designed and marked on the skin. Only the lesion and the required margin of adjacent skin were excised before the defect was closed in an optimal direction. Dog ears were removed if appropriate. Precise measurements were made at each step. RESULTS: Twenty-eight percent of wounds could be closed with a flat sutured wound without the need for dog ear repair, 38% required one dog ear repair, and 34% two. Overall, the sutured wound length was 21% shorter and the wound direction different from the predicted ellipse in 45% of cases. CONCLUSION: Excision with dog ear repair results in significantly shorter and potentially better oriented wounds than those achieved by elliptical excision. For excision and closure of skin tumors this technique should be considered as the method of choice.

Photoprotective action of emollients in ultraviolet therapy of psoriasis.

An in vitro technique was used to measure the monochromatic protection factors of all emollients available on prescription. The action spectra for ultraviolet erythema and erythema in psoralen-sensitized skin were used to calculate, for each emollient, erythema protection factors relevant to UVB phototherapy and psoralen photochemotherapy, respectively. Of the 40 products tested, 22 (55%) had a UVB erythema protection factor > 1.2 at an application density of 2 microliters/cm2, and 31 (78%) at an application density of 4 microliters/cm2. Fewer products, 25% at 2 microliters/cm2 and 50% at 4 microliters/cm2, had a psoralen erythema protection factor > 1.2. A protection factor of 1.2 is equivalent to a reduction in ultraviolet dose of 17%, and is thus likely to be of clinical importance. These results allow a choice of emollient products which may improve response by increasing transmission of radiation through psoriasis scale without a concomitant decrease in transmission due to a sunscreening action.